Search results for: ancient asurgical imaging

Authors: Raheel Shakoor Siddiqui, Sanjay Narayana Murthy, Manikandar Srinivas Cheruvu, Kash Akhtar

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Major trauma is a dynamic public health epidemic that is continuously evolving. Major trauma care services rely on multi-disciplinary team input involving highly trained pre and in-hospital critical care teams. Pre-hospital critical care teams (PHCCTs), major trauma centres (MTCs), trauma units, and rehabilitation facilities all form an efficient and organised trauma system. England comprises 27 MTCs funded by the National Health Service (NHS). Major trauma care entails enhanced resuscitation protocols coupled with the expertise of dedicated trauma teams and rapid radiological imaging to improve trauma outcomes. Literature reports a change in the demographic of major trauma as elderly patients (silver trauma) with injuries sustained from a fall of 2 metres or less commonly present to services. Evidence of an increasing population age with multiple comorbidities necessitates treatment within the first hour of injury (golden hour) to improve trauma survival outcomes. Staffing and funding pressures within the NHS have subsequently led to a shortfall of available physician-led PHCCTs. Thus, there is a strong emphasis on targeted research and funding to appropriately deploy resources to deprived areas. This review article will discuss the current English trauma system whilst critically appraising present challenges, identifying insufficiencies, and recommending aims for an improved future trauma system in England.

Keywords: trauma, orthopaedics, major trauma, trauma system, trauma network

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Authors: Vaia N. Koukou, Niki D. Martini, George P. Fountos, Christos M. Michail, Athanasios Bakas, Ioannis S. Kandarakis, George C. Nikiforidis

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Various substitute materials of calcifications are used in phantom measurements and simulation studies in mammography. These include calcium carbonate, calcium oxalate, hydroxyapatite and aluminum. The aim of this study is to compare the contrast-to-noise ratio (CNR) values of the different calcification types using the dual energy method. The constructed calcification phantom consisted of three different calcification types and thicknesses: hydroxyapatite, calcite and calcium oxalate of 100, 200, 300 thicknesses. The breast tissue equivalent materials were polyethylene and polymethyl methacrylate slabs simulating adipose tissue and glandular tissue, respectively. The total thickness was 4.2 cm with 50% fixed glandularity. The low- (LE) and high-energy (HE) images were obtained from a tungsten anode using 40 kV filtered with 0.1 mm cadmium and 70 kV filtered with 1 mm copper, respectively. A high resolution complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) X-ray detector was used. The total mean glandular dose (MGD) and entrance surface dose (ESD) from the LE and HE images were constrained to typical levels (MGD=1.62 mGy and ESD=1.92 mGy). On average, the CNR of hydroxyapatite calcifications was 1.4 times that of calcite calcifications and 2.5 times that of calcium oxalate calcifications. The higher CNR values of hydroxyapatite are attributed to its attenuation properties compared to the other calcification materials, leading to higher contrast in the dual energy image. This work was supported by Grant Ε.040 from the Research Committee of the University of Patras (Programme K. Karatheodori).

Keywords: calcification materials, CNR, dual energy, X-rays

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Authors: Idris Garba, Aisha Rabiu Abdullahi, Mansur Yahuza, Akintade Dare

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Background: CT urography (CTU) is efficient radiological examination for the evaluation of the urinary system disorders. However, patients are exposed to a significant radiation dose which is in a way associated with increased cancer risks. Objectives: To determine Computed Tomography Dose Index following CTU, and to evaluate organs equivalent doses. Materials and Methods: A prospective cohort study was carried at a tertiary institution located in Kano northwestern. Ethical clearance was sought and obtained from the research ethics board of the institution. Demographic, scan parameters and CT radiation dose data were obtained from patients that had CTU procedure. Effective dose, organ equivalent doses, and cancer risks were estimated using SPSS statistical software version 16 and CT dose calculator software. Result: A total of 56 patients were included in the study, consisting of 29 males and 27 females. The common indication for CTU examination was found to be renal cyst seen commonly among young adults (15-44yrs). CT radiation dose values in DLP, CTDI and effective dose for CTU were 2320 mGy cm, CTDIw 9.67 mGy and 35.04 mSv respectively. The probability of cancer risks was estimated to be 600 per a million CTU examinations. Conclusion: In this study, the radiation dose for CTU is considered significantly high, with increase in cancer risks probability. Wide radiation dose variations between patient doses suggest that optimization is not fulfilled yet. Patient radiation dose estimate should be taken into consideration when imaging protocols are established for CT urography.

Keywords: CT urography, cancer risks, effective dose, radiation exposure

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Authors: Jamal Ahmad

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The Sanctuary of the Kafirs is a sanctified place for the people of Kalash which contain the sacred remains of their culture. The existence of the cultural Sanctuary is not limited up to boundaries of culture but its canopy also contain the spiritual attachments in terms of religion, rituals, introspections, myths, customs and living standards. Culture is the manifestation of the human intellectual achievement in a qualitative phenomenon of a place. The ethnic people of Hindu Kush (Kalash) are an indigenous group that practices Animism. They believe in Animistic Symbology i-e the material universe has high spiritual power. The Animism in their living standard comes from the high spiritualized and sacred sacrifices of animals goats, sheep etc. in their festivals which is the symbol of purity. Similarly certain cultural and religious phenomena make its behavior, its living pattern, its fairy tales, its birth and even its death unique. The scattered and the vanishing fragments of the Kafiristan, demands the phenomenal solution which molds all these factors into preserving standards. It demands a place of belief where, their unique culture, religion, festivals and life style make a sincere base for future existence, and such phenomena of place will consciously or unconsciously molds these ideas into building fabric. The Sanctuary contains ancient vandalized cemetery, the qaliq* the mujnatikeen*, the jastaks*, dewadoor* an amphitheater for dancing and ritual performances, an herbal garden and a profile sanctuary of the blood line of Kalash. The Case-Analysis provokes a new architecture of place, as the Phenomenological Architecture, which requires a place and phenomenon to take place. The Animistic Symbology and Phenomenology both are the part of their life but needs to reveal its hidden meaning and existence i-e (The Balamain, the alpine meadows, the sacred river). The Architectural work is strengthened by the philosophies of Animism and Phenomenology which make it easy to understand. The Scope of work is to reincarnate the ethical boundaries between the neighboring tribes and the Kafirs, by a series of dwellings, cultural and religious communal buildings and spaces, gardens and streets layout under the umbrella of ethical beliefs of Kalash community. So we conclude to build the Sanctuary of the Kafirs, in Bamboret valley of Kalash.

Keywords: Qaliq, Mujnatikeen, Dewadoor, Jastaks

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Authors: Sayed Mansour, Mohammad Aldoasri, Nagib Elmarzugi, Nadia A. Al-Mouallimi

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The archaeological large stone used in construction of ancient Pharaonic tombs, temples, obelisks and other sculptures, always subject to physicomechanical deterioration and destructive forces, leading to their partial or total broken. The task of reassembling this type of artifact represent a big challenge for the conservators. Recently, the researchers are turning to new technologies to improve the properties of traditional adhesive materials and techniques used in re-assembly of broken large stone. The epoxy resins are used extensively in stone conservation and re-assembly of broken stone because of their outstanding mechanical properties. The introduction of nanoparticles to polymeric adhesives at low percentages may lead to substantial improvements of their mechanical performances in structural joints and large objects. The aim of this study is to evaluate the effectiveness of clay nanoparticles in enhancing the performances of epoxy adhesives used in re-assembly of archaeological massive stone by adding proper amounts of those nanoparticles. The nanoparticles reinforced epoxy nanocomposite was prepared by direct melt mixing with a nanoparticles content of 3% (w/v), and then mould forming in the form of rectangular samples, and used as adhesive for experimental stone samples. Scanning electron microscopy (SEM) was employed to investigate the morphology of the prepared nanocomposites, and the distribution of nanoparticles inside the composites. The stability and efficiency of the prepared epoxy-nanocomposites and stone block assemblies with new formulated adhesives were tested by aging artificially the samples under different environmental conditions. The effect of incorporating clay nanoparticles on the mechanical properties of epoxy adhesives was evaluated comparatively before and after aging by measuring the tensile, compressive, and Elongation strength tests. The morphological studies revealed that the mixture process between epoxy and nanoparticles has succeeded with a relatively homogeneous morphology and good dispersion in low nano-particles loadings in epoxy matrix was obtained. The results show that the epoxy-clay nanocomposites exhibited superior tensile, compressive, and Elongation strength. Moreover, a marked improvement of the mechanical properties of stone joints increased in all states by adding nano-clay to epoxy in comparison with pure epoxy resin.

Keywords: epoxy resins, nanocomposites, clay nanoparticles, re-assembly, archaeological massive stones, mechanical properties

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Authors: Loveneet Kaur

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Introduction: Osteoarthritis (OA) is one of the leading causes of disability, and the knee is the most commonly affected joint in the body. The last resort for treatment of knee OA is Total Knee Replacement (TKR) surgery. Despite numerous advances in prosthetic design, patients do not reach normal function after surgery. Current surgical decisions are made on 2D radiographs and patient interviews. Aims: The aim of this study was to compare knee kinematics pre and post-TKR surgery using computer-animated images of patient-specific models under everyday conditions. Methods: 7 subjects were recruited for the study. Subjects underwent 3D gait analysis during 4 everyday activities and medical imaging of the knee joint pre- and one-month post-surgery. A 3D model was created from each of the scans, and the kinematic gait analysis data was used to animate the images. Results: Improvements were seen in a range of motion in all 4 activities 1-year post-surgery. The preoperative 3D images provide detailed information on the anatomy of the osteoarthritic knee. The postoperative images demonstrate potential future problems associated with the implant. Although not accurate enough to be of clinical use, the animated data can provide valuable insight into what conditions cause damage to both the osteoarthritic and prosthetic knee joints. As the animated data does not require specialist training to view, the images can be utilized across the fields of health professionals and manufacturing in the assessment and treatment of patients pre and post-knee replacement surgery. Future improvements in the collection and processing of data may yield clinically useful data. Conclusion: Although not yet of clinical use, the potential application of 3D animations of the knee joint pre and post-surgery is widespread.

Keywords: Orthoporosis, Ortharthritis, knee replacement, TKR

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Authors: Kheireddine El-Boubbou

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Drug delivery to target human acute myeloid leukemia (AML) using a nanoparticulate chemotherapeutic formulation that can deliver drugs selectively to AML cancer is hugely needed. In this work, we report the development of a nanoformulation made of polymeric-stabilized multifunctional magnetic iron oxide nanoparticles (PMNP) loaded with the anticancer drug Doxorubicin (Dox) as a promising drug carrier to treat AML. Dox@PMNP conjugates simultaneously exhibited high drug content, maximized fluorescence, and excellent release properties. Nanoparticulate uptake and cell death following addition of Dox@PMNPs were then evaluated in different types of human AML target cells, as well as on normal human cells. While the unloaded MNPs were not toxic to any of the cells, Dox@PMNPs were found to be highly toxic to the different AML cell lines, albeit at different inhibitory concentrations (IC₅₀ values), but showed very little toxicity towards the normal cells. In comparison, free Dox showed significant potency concurrently to all the cell lines, suggesting huge potentials for the use of Dox@PMNPs as selective AML anticancer cargos. Live confocal imaging, fluorescence and electron microscopy confirmed that Dox is indeed delivered to the nucleus in relatively short periods of time, causing apoptotic cell death. Importantly, this targeted payload may potentially enhance the effectiveness of the drug in AML patients and may further allow physicians to image leukemic cells exposed to Dox@PMNPs using MRI.

Keywords: magnetic nanoparticles, drug delivery, acute myeloid leukemia, iron oxide, cancer nanotherapy

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Authors: Zahra Asgharpour, Eric Renteria, Sebastian De Boodt

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There is a growing trend towards personalization of medical care, as evidenced by the emphasis on outcomes based medicine, the latest developments in CT and MR imaging and personalized treatment in a variety of surgical disciplines. 3D Printing has been introduced and applied in the medical field since 2000. The first applications were in the field of dental implants and custom prosthetics. According to recent publications, 3D printing in the medical field has been used in a wide range of applications which can be organized into several categories including implants, prosthetics, anatomical models and tissue bioprinting. Some of these categories are still in their infancy stage of the concept of proof while others are in application phase such as the design and manufacturing of customized implants and prosthesis. The approach of 3D printing in this category has been successfully used in the health care sector to make both standard and complex implants within a reasonable amount of time. In this study, some of the clinical applications of 3D printing in design and manufacturing of a patient-specific hip implant would be explained. In cases where patients have complex bone geometries or are undergoing a complex revision on hip replacement, the traditional surgical methods are not efficient, and hence these patients require patient-specific approaches. There are major advantages in using this new technology for medical applications, however, in order to get this technology widely accepted in medical device industry, there is a need for gaining more acceptance from the medical device regulatory offices. This is a challenge that is moving onward and will help the technology find its way at the end as an accepted manufacturing method for medical device industry in an international scale. The discussion will conclude with some examples describing the future directions of 3D Medical Printing.

Keywords: CT/MRI, image processing, 3D printing, medical devices, patient specific implants

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Authors: Chen-En Lin, Lih-Rou Rau, Jiunn-Woei Liaw, Shiao-Wen Tsai

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The unique optical properties of plasmon resonance metallic particles have attracted considerable applications in the fields of physics, chemistry and biology. Metal-Enhanced Fluorescence (MEF) effect is one of the useful applications. MEF effect stated that fluorescence intensity can be quenched or be enhanced depending on the distance between fluorophores and the metal nanoparticles. Silver nanoparticles have used widely in antibacterial studies. However, the major limitation for silver nanoparticles (AgNPs) in biomedical application is well-known cytotoxicity on cells. There were numerous literatures have been devoted to overcome the disadvantage. The aim of the study is to evaluate the cytotoxicity and biocompatibility of silica coated AgNPs against NIH-3T3 cells. The results were shown that NIH-3T3 cells started to detach, shrink, become rounded and finally be irregular in shape after 24 h of exposure at 10 µg/ml AgNPs. Besides, compared with untreated cells, the cell viability significantly decreased to 60% and 40% which were exposed to 10 µg/ml and 20 µg/ml AgNPs respectively. The result was consistent with previously reported findings that AgNPs induced cytotoxicity was concentration dependent. However, the morphology and cell viability of cells appeared similar to the control group when exposed to 20 µg/ml of silica coated AgNPs. We further utilized the dark-field hyperspectral imaging system to analysis the optical properties of the intracellular nanoparticles. The image displayed that the red shift of the surface plasmonic resonances band of the enclosed AgNPs further confirms the agglomerate of the AgNPs rather than their distribution in cytoplasm. In conclusion, the study demonstrated the silica coated of AgNPs showed well biocompatibility and significant lower cytotoxicity compared with bare AgNPs.

Keywords: silver nanoparticles, silica, cell viability, morphology

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Authors: Mohamad Musa

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The history of mental health practices and services in the Middle East region has been deeply intertwined with its rich cultural, religious, and societal context. Tracing back to ancient times, mental health approaches were heavily influenced by the traditions of major monotheistic religions, with a strong emphasis on spiritual and traditional healing methods. As psychiatric institutions and Western medicine gradually gained a foothold in the region during the 20th century, a notable shift occurred. However, the integration of Western psychiatric practices faced significant challenges due to cultural barriers and deeply rooted beliefs. Families and communities often turned to traditional healers and religious practices as their initial recourse for mental health concerns, viewing Western interventions with skepticism and hesitation. Historically, mental health services in the Middle East have been overshadowed by a focus on physical health and the biomedical model. Mental illness carried substantial stigma, with individuals and families often reluctant to disclose mental health struggles due to fears of societal ostracization and discrimination. This stigma posed a significant barrier to accessing and accepting formal mental health support. Later in the 20th century, governments in the Middle East began recognizing the need for modernizing mental health services and integrating them into the broader healthcare system. However, this process was hindered by several factors, including limited resources, inadequate training for healthcare professionals, and ongoing conflicts and instability in certain regions, which disrupted the delivery of mental health services. As the 21st century progressed, several Middle Eastern nations, particularly those in the Arabian Gulf region, began implementing national mental health strategies and legislative reforms to address the growing need for comprehensive mental health care. These efforts aimed to destigmatize mental illness, protect the rights of individuals with mental health conditions, and promote public awareness and education. Despite these positive developments, the historical legacy of stigma, cultural barriers, and limited resources continues to pose challenges in the provision of accessible and culturally responsive mental health services across the diverse populations of the Middle East.

Keywords: mental health, history, middle east, literature review

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Authors: Emre Kishalı, Neslihan TürkmenoğLu Bayraktar

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Historical buildings may face various impacts throughout their life cycle. There have been environmental, structural, public works actions on old monuments influencing sustainability and maintenance issues. As a result, ancient monuments can have been undergone various changes in the context of restoration and repair. Currently, these buildings face integrated conditions including city planning macro solutions, old intervention methods, modifications in building envelope and artefacts in terms of conservation. Moreover, documentation of phases is an essential for assessing the historical building, yet it can result in highly complicated and interwoven issues. Herein, two monuments constructed in the 16th century are selected as case studies in Kocaeli, Turkey which are located in different micro climatic conditions and/or exposed to different interventions and which are important for the city as cultural property. Pertev Paşa Mosque (also known as Yenicuma Mosque) -constructed by Architect Sinan-; Gebze Çoban Mustafa Paşa Mosque -constructed in 1523 and known as the work of Architect Sinan but various names asserted as the architect of building according to resources. Active water infiltration and damages, recent material interventions, hidden niches, and foundation techniques of the mosque are investigated via Infrared Thermography under the project of 114K284, “Non-Destructive Test Applications, in the Context of Planned Conservation, through Historical Mosques of Kocaeli: Coban Mustafa Pasa Mosque, Fevziye Mosque and Pertev Pasa Mosque” funded by TUBITAK. It is aimed to reveal active deteriorations on building elements generated by unwanted effects of structural and climatic conditions, historical interventions, and modifications by monitoring the variation of surface temperature and humidity by IRT visualization method which is an important non- destructive process for investigation of monuments in the conservation field in the context of planned conservation. It is also concluded that in-situ monitoring process via IRT through different climatic conditions give substantial information on the behaviour of the envelope to the physical environmental conditions by observation of thermal performance, degradations. However, it is obvious that monitoring of historical buildings cannot be pursued by implementing a single non-destructive technique to have complete data of the structure.

Keywords: IRT, non-destructive test, planned conservation, mosque

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Authors: Liyang Yue, Bing Yan, James N. Monks, Rakesh Dhama, Zengbo Wang, Oleg V. Minin, Igor V. Minin

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A particle can function as a refractive lens to focus a plane wave, generating a narrow, high intensive, weak-diverging beam within a sub-wavelength volume, known as the ‘photonic jet’. Refractive index contrast (particle to background media) and scaling effect of the dielectric particle (relative-to-wavelength size) play key roles in photonic jet formation, rather than the shape of particle-lens. Waist (full width of half maximum, FWHM) of a photonic jet could be beyond the diffraction limit and smaller than the Airy disk, which defines the minimum distance between two objects to be imaged as two instead of one. Many important applications for imaging and sensing have been afforded based upon the super-resolution characteristic of the photonic jet. It is known that apodization method, in the form of an amplitude pupil-mask centrally situated on a particle-lens, can further reduce the waist of a photonic nanojet, however, usually lower its intensity at the focus due to blocking of the incident light. In this paper, the anomalously intensity-enhanced apodization effect was discovered in the near-field via numerical simulation. It was also experimentally verified by a scale model using a copper-masked Teflon cuboid solid immersion lens (SIL) with 22 mm side length under radiation of a plane wave with 8 mm wavelength. Peak intensity enhancement and the lateral resolution of the produced photonic jet increased by about 36.0 % and 36.4 % in this approach, respectively. This phenomenon may possess the scale effect and would be valid in multiple frequency bands.

Keywords: apodization, particle-lens, scattering, near-field optics

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Authors: Radhamanohar Aepuru, R. V. Mangalaraja

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Flexible electronic devices have drawn potential interest and provide significant new insights to develop energy conversion and storage devices such as photodetectors and nanogenerators. Recently, self-powered electronic systems have captivated huge attention for next generation MEMS/NEMS devices that can operate independently by generating built-in field without any need of external bias voltage and have wide variety of applications in telecommunication, imaging, environmental and defence sectors. The basic physical process involved in these devices are charge generation, separation, and charge flow across the electrodes. Many inorganic nanostructures have been exploring to fabricate various optoelectronic and electromechanical devices. However, the interaction of nanostructures and their excited charge carrier dynamics, photoinduced charge separation, and fast carrier mobility are yet to be studied. The proposed research is to address one such area and to realize the self-powered electronic devices. In the present work, nanocomposites of inorganic nanostructures based on ZnO, metal halide perovskites; and polyvinylidene fluoride (PVDF) based nanocomposites are realized for photodetectors and nanogenerators. The characterization of the inorganic nanostructures is carried out through steady state optical absorption and luminescence spectroscopies as well as X-ray diffraction and high-resolution transmission electron microscopy (TEM) studies. The detailed carrier dynamics is investigated using various spectroscopic techniques. The developed composite nanostructures exhibit significant optical and electrical properties, which have wide potential applications in various MEMS/NEMS devices such as photodetectors and nanogenerators.

Keywords: dielectrics, nanocomposites, nanogenerators, photodetectors

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Authors: Sung-Hee Nam, Kwang-Gill Lee, You-Young Jo, HaeYong Kweon

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Entomopathogenic fungi is a Cordyceps species that is isolated from dead silkworm and cicada. Fungi on cicadas were described in old Chinese medicinal books and From ancient times, vegetable wasps and plant worms were widely known to have active substance and have been studied for pharmacological use. Among many fungi belonging to the genus Cordyceps, Cordyceps sinensis have been demonstrated to yield natural products possessing various biological activities and many bioactive components. Generally, It is commonly used to replenish the kidney and soothe the lung, and for the treatment of fatigue. Due to their commercial and economic importance, the demand for Cordyceps has been rapidly increased. However, a supply of Cordyceps specimen could not meet the increasing demand because of their sole dependence on field collection and habitat destruction. Because it is difficult to obtain many insect hosts in nature and the edibility of host insect needs to be verified in a pharmacological aspect. Recently, this setback was overcome that P. tenuipes was able to be cultivated in a large scale using silkworm as host. Pharmacological effects of P. tenuipes cultured on silkworm such as strengthening immune function, anti-fatigue, anti-tumor activity and controlling liver etc have been proved. They are widely commercialized. In this study, we attempted to establish a method for stable growth inhibition of P. tenuipes on silkworm hosts and an optimal condition for synnemata formation. To determine optimum culturing conditions, temperature and light conditions were varied. The length and number of synnemata was highest at 25℃ temperature and 100~300 lux illumination. On an average, the synnemata of wild P. tenuipes measures 70 ㎜ in length and 20 in number; those of the cultured strain were relatively shorter and more in number. The number of synnemata may have increased as a result of inoculating the host with highly concentrated conidia, while the length may have decreased due to limited nutrition per individual. It is not able that changes in light illumination cause morphological variations in the synnemata. However, regulation of only light and temperature could not produce stromata like perithecia, asci, and ascospores. Yamanaka reported that although a complete fruiting body can be produced under optimal culture conditions, it should be regarded as synnemata because it does not develop into an ascoma bearing ascospores.

Keywords: paecilomyces tenuipes, entomopathogenic fungi, silkworm larva, bombyx mori

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Authors: Ge Sun, Monika Trzpis, Robbert J. de Haas, Paul M. A. Broens

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Introduction: Dynamic magnetic resonance defecography is frequently used to assess defecation disorders. We aimed to investigate the usefulness of dynamic magnetic resonance defecography for assessing the severity of defecation disorder. Methods: We included patients retrospectively from our tertiary referral hospital who had undergone dynamic magnetic resonance defecography, anorectal manometry, and anal electrical sensitivity tests to assess defecation disorders between 2014 and 2020. The primary outcome was the association between the dynamic magnetic resonance defecography variables and the severity of defecation disorders. We assessed the severity of fecal incontinence and constipation with the Wexner incontinence and Agachan constipation scores. Results: Out of the 32 patients included, 24 completed the defecation questionnaire. During defecation, the M line length at magnetic resonance correlated with the Agachan score (r = 0.45, p = 0.03) and was associated with anal sphincter pressure (r=0.39, p=0.03) just before defecation. During rest and squeezing, the H line length at imaging correlated with the Wexner incontinence score (r=0.49, p=0.01 and r=0.69, p< 0.001, respectively). H line length also correlated positively with the anal electrical sensation threshold during squeezing (r=0.50, p=0.004) and during rest (r= 0.42, p=0.02). Conclusions: The M and H line lengths at dynamic magnetic resonance defecography can be used to assess the severity of constipation and fecal incontinence respectively and reflect anatomic changes of the pelvic floor. However, as these anatomic changes are generally late-stage and irreversible, anal manometry seems a better diagnostic approach to assess early and potentially reversible changes in patients with defecation disorders.

Keywords: defecation disorders, dynamic magnetic resonance defecography, anorectal manometry, anal electrical sensitivity tests, H line, M line

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Authors: ShyamKrishna Kirithivasan, Shreyas Battula, Aditi Soori, Richa Ramesh, Ramamoorthy Srinath

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The human brain, among the most complex and mysterious aspects of the body, harbors vast potential for extensive exploration. Unraveling these enigmas, especially within neural perception and cognition, delves into the realm of neural decoding. Harnessing advancements in generative AI, particularly in Visual Computing, seeks to elucidate how the brain comprehends visual stimuli observed by humans. The paper endeavors to reconstruct human-perceived visual stimuli using Functional Magnetic Resonance Imaging (fMRI). This fMRI data is then processed through pre-trained deep-learning models to recreate the stimuli. Introducing a new architecture named LatentNeuroNet, the aim is to achieve the utmost semantic fidelity in stimuli reconstruction. The approach employs a Latent Diffusion Model (LDM) - Stable Diffusion v1.5, emphasizing semantic accuracy and generating superior quality outputs. This addresses the limitations of prior methods, such as GANs, known for poor semantic performance and inherent instability. Text conditioning within the LDM's denoising process is handled by extracting text from the brain's ventral visual cortex region. This extracted text undergoes processing through a Bootstrapping Language-Image Pre-training (BLIP) encoder before it is injected into the denoising process. In conclusion, a successful architecture is developed that reconstructs the visual stimuli perceived and finally, this research provides us with enough evidence to identify the most influential regions of the brain responsible for cognition and perception.

Keywords: BLIP, fMRI, latent diffusion model, neural perception.

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Authors: Vijaykumar M. Baragi, Ramtilak Gattu, Gabriela Trifan, John L. Woodard, K. Meyers, Tim S. Halstead, Eric Hipple, Ewart Mark Haacke, Randall R. Benson

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NFL players, by virtue of their exposure to repetitive head injury, are at least twice as likely to develop Alzheimer's disease (AD) and dementia as the general population. Early recognition and intervention prior to onset of clinical symptoms could potentially avert/delay the long-term consequences of these diseases. Since AD is thought to have a long preclinical incubation period, the aim of the current research was to determine whether former NFL players, referred to a depression center, showed evidence of incipient dementia in their structural imaging prior to diagnosis of dementia. Thus, to identify neuroimaging markers of AD, against which former NFL players would be compared, we conducted a comprehensive volumetric analysis using a cohort of early stage AD patients (ADNI) to produce a set of brain regions demonstrating sensitivity to early AD pathology (i.e., the “AD fingerprint”). A cohort of 46 former NFL players’ brain MRIs were then interrogated using the AD fingerprint. Brain scans were done using a T1-weighted MPRAGE sequence. The Free Surfer image analysis suite (version 6.0) was used to obtain the volumetric and cortical thickness data. A total of 55 brain regions demonstrated significant atrophy or ex vacuo dilatation bilaterally in AD patients vs. healthy controls. Of the 46 former NFL players, 19 (41%) demonstrated a greater than expected number of atrophied/dilated AD regions when compared with age-matched controls, presumably reflecting AD pathology.

Keywords: alzheimers, neuroimaging biomarkers, traumatic brain injury, free surfer, ADNI

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Authors: J. B. Athavale, Sean Clarke

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Introduction According to ancient Indian scriptures, a person’s consciousness includes the physical body, the vital energy sheath (Pranshakti), the mental body (which includes one’s feelings and emotions), the intellectual body (which refers to one’s decision-making ability), and the Soul (which is the God Principle that resides in every person). Apart from the physical body, all the other aspects are subtle in nature. In today’s world, much attention is given to one’s physical appearance and intellectual prowess. While there have been improvements in the attention given to mental health, its complete nature is not understood, and in many cultures, mental ill health is considered taboo and looked down upon. Regarding the spiritual well-being of a person, our spiritual research has shown that people’s understanding and efforts are mostly lacking and superficial as they do not conform to Universal Spiritual Principles. Also, true well-being occurs only when all the bodies are healthy. Methodology The spiritual research team at the University has found that the spiritual aspect of a person’s life affects all the physical, psychological, and intellectual bodies of a person resulting in ill health. Cleansing these bodies at a spiritual level is essential to regain well-being. Using Aura and Energy Scanners and advanced sixth sense, we studied what causes spiritual impurity in various bodies and how to cleanse them. We measured the spiritual vibrations of a person and how they get affected due to various daily activities. For example, we studied the difference in a person’s aura before and after applying chemical-based makeup vs. natural makeup. Key Findings From the various spiritual research experiments we conducted, we found that: • All our actions and our thoughts affect our various bodies and have the potential to change the aura for the better or worse. • When there is an increase in negative vibrations around a person, negative energies from the subtle dimension are more likely to affect a person. • As the person’s spiritual level increases, the positivity in their aura also increases, and it is much easier to cleanse the various bodies spiritually. • Spiritual practice is like a general spiritual tonic that increases the positivity in one’s aura. The benefits of this are that it leads to mental stability and intellectual clarity. • Spiritual healing remedies augment any spiritual practice to obtain a faster healing effect. Conclusion Taking care of oneself spiritually has a positive halo effect on all one’s bodies. Spiritual cleansing is required regularly if one wants to attain a state of well-being. Spiritual practice and spiritual healing lead to spiritual growth, stability of mind, and less stress and reactions. Spiritually purer people affect the environment positively, and there is less unrest and more harmony between man and nature.

Keywords: body, spirituality, cleansing, consciousness

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Authors: Ahmed A. Abd El Rahim, Mohamed M. M. Essa, Magdy M. A. Shabana, Said A. Mohamed, Mohamed Ibrahim Mabrouk

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Background: Sacroiliac joint (SIJ) dysfunction is considered the main cause of pregnancy-related back pain, which may continue to persist postnatally. Myofascial release technique (MFR) is an application of low-intensity, prolonged stretch to myofascial structures to improve function by increasing the sliding properties of restricted myofascial tissues. Purpose: This study was designed to investigate the effect of MFR on postnatal SIJ hypo-mobility. Materials and Methods: Fifty postnatal women complaining of SIJ hypo-mobility participated in this study. Their ages ranged from 26 to 35 yrs., and their body mass index (BMI) didn`t exceed 30 kg/m2. They were randomly assigned to two equal groups, group A (Gr. A) and group B (Gr. B). Both groups received three sessions per week for eight successive weeks. Gr. A received a traditional physical therapy program, while Gr. B received a traditional physical therapy program in addition to MFR. Doppler imaging of vibration was utilized to measure SIJ mobility pre- and post-intervention, and an electronic digital goniometer was used to measure back flexion and extension Range of motion. Results: Findings revealed a statistical improvement in post-intervention values of SIJ mobility in addition to trunk flexion and extension ROM in Gr. B compared to Gr. A (P<0.001). Conclusion: Adding MFR to traditional physical therapy programs is highly recommended in the treatment of SIJ hypo-mobility in postnatal women.

Keywords: sacroiliac hypo-mobility, sacroiliac dysfunction, myofascial release technique, traditional physical therapy, postnatal

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Authors: Alberto Abello Moreno-Cid

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Mummification was the process through which immortality was granted to the deceased, so it was of extreme importance to the Egyptians. The techniques of embalming had evolved over the centuries, and specialists created increasingly sophisticated tools. However, due to its eminently religious nature, knowledge about everything related to this practice was jealously preserved, and the testimonies that have survived to our time are scarce. For this reason, embalming instruments found in archaeological excavations are uncommon. The tomb of the Vizier Amenhotep Huy (AT No. -28-), located in the el-Assasif necropolis that is being excavated since 2009 by the team of the Institute of Ancient Egyptian Studies, has been the scene of some discoveries of this type that evidences the existence of mummification practices in this place after the New Kingdom. The clysters or enemas are the fundamental tools in the second type of mummification described by the historian Herodotus to introduce caustic solutions inside the body of the deceased. Nevertheless, such objects only have been found in three locations: the tomb of Ankh-Hor in Luxor, where a copper enema belonged to the prophet of Ammon Uah-ib-Ra came to light; the excavation of the tomb of Menekh-ib-Nekau in Abusir, where was also found one made of copper; and the excavations in the Bucheum, where two more artifacts were discovered, also made of copper but in different shapes and sizes. Both of them were used for the mummification of sacred animals and this is the reason they vary significantly. Therefore, the object found in the tomb No. -28-, is the first known made of faience of all these peculiar tools and the oldest known until now, dated in the Third Intermediate Period (circa 1070-650 B.C.). This paper bases its investigation on the study of those parallelisms, the material, the current archaeological context and the full analysis and reconstruction of the object in question. The key point is the use of faience in the production of this item: creating a device intended to be in constant use seems to be a first illogical compared to other samples made of copper. Faience around the area of Deir el-Bahari had a strong religious component, associated with solar myths and principles of the resurrection, connected to the Osirian that characterises the mummification procedure. The study allows to refute some of the premises which are held unalterable in Egyptology, verifying the utilization of these sort of pieces, understanding its way of use and showing that this type of mummification was also applied to the highest social stratum, in which case the tools were thought out of an exceptional quality and religious symbolism.

Keywords: clyster, el-Assasif, embalming, faience enema mummification, Theban necropolis

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Authors: Balakrishna Valluru, Ruth Suckling

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A 16 year old male was found collapsed on the road following stab injuries to the chest and abdomen and was transported to the emergency department by ambulance. On arrival in the emergency department the patient was breathless and appeared pale. He was maintaining his airway with spontaneous breathing and had a heart rate of 122 beats per minute with a blood pressure of 83/63 mmHg. He was resuscitated initially with three units of packed red cells. Clinical examination identified three incisional wounds each measuring 2 cm. These were in the left para-sternal region, right infra-scapular region and left upper quadrant of the abdomen. The chest wound over the left parasternal area at the level of 4tth intercostal space was bleeding intermittently on leaning forwards and was relieving his breathlessness intermittently. CT imaging was performed to characterize his injuries and determine his management. CT scan of chest and abdomen showed moderate size haemopericardium with left sided haemopneumothorax. The patient underwent urgent surgical repair of the left ventricle and left anterior descending artery. He recovered without complications and was discharged from the hospital. This case highlights the fact that the potential to develop a life threatening cardiac tamponade was mitigated by the left parasternal stab wound. This injury fortuitously provided a pericardial window through which the bleeding from the injured left ventricle and left anterior descending artery could drain into the left hemithorax providing an opportunity for timely surgical intervention to repair the cardiac injuries.

Keywords: stab, incisional, haemo-pericardium, haemo-pneumothorax

Procedia PDF Downloads 184

Authors: Behnaz Sohani, Sahand Shahalinezhad, Amir Rahmani, Aliyu Aliyu

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Recently, medical imaging and specifically medical image processing is becoming one of the most dynamically developing areas of medical science. It has led to the emergence of new approaches in terms of the prevention, diagnosis, and treatment of various diseases. In the process of diagnosis of lung cancer, medical professionals rely on computed tomography (CT) scans, in which failure to correctly identify masses can lead to incorrect diagnosis or sampling of lung tissue. Identification and demarcation of masses in terms of detecting cancer within lung tissue are critical challenges in diagnosis. In this work, a segmentation system in image processing techniques has been applied for detection purposes. Particularly, the use and validation of a novel lung cancer detection algorithm have been presented through simulation. This has been performed employing CT images based on multilevel thresholding. The proposed technique consists of segmentation, feature extraction, and feature selection and classification. More in detail, the features with useful information are selected after featuring extraction. Eventually, the output image of lung cancer is obtained with 96.3% accuracy and 87.25%. The purpose of feature extraction applying the proposed approach is to transform the raw data into a more usable form for subsequent statistical processing. Future steps will involve employing the current feature extraction method to achieve more accurate resulting images, including further details available to machine vision systems to recognise objects in lung CT scan images.

Keywords: lung cancer detection, image segmentation, lung computed tomography (CT) images, medical image processing

Procedia PDF Downloads 73

Authors: Asmaa Tahiri, Mouktafi Amine

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A substantial number of traditional medical research has been put forward to managing and treating mental disorders. At the present time, to our best knowledge, it is believed that fundamental understanding of the underlying causes of the majority psychological disorders needs to be explored further to inform early diagnosis, managing symptoms and treatment. The emerging field of evolutionary psychology is a promising prospect to address the origin of mental disorders, potentially leading to more effective treatments. Schizophrenia as a topical mental disorder has been linked to the evolutionary adaptation of the human brain represented in the brain connectivity and asymmetry directly linked to humans higher brain cognition in contrast to other primates being our direct living representation of the structure and connectivity of our earliest common African ancestors. As proposed in the evolutionary psychology scientific literature the pathophysiology of schizophrenia is expressed and directly linked to altered connectivity between the Hippocampal Formation (HF) and Dorsolateral Prefrontal Cortex (DLPFC). This research paper presents the results of the use of tractography analysis using multiple open access Diffusion Weighted Imaging (DWI) datasets of healthy subjects, schizophrenia-affected subjects and primates to illustrate the relevance of the aforementioned brain regions connectivity and the underlying evolutionary changes in the human brain. Deterministic fiber tracking and streamline analysis were used to generate connectivity matrices from the DWI datasets overlaid to compute distances and highlight disconnectivity patterns in conjunction with other fiber tracking metrics; Fractional Anisotropy (FA), Mean Diffusivity (MD) and Radial Diffusivity (RD).

Keywords: tractography, evolutionary psychology, schizophrenia, brain connectivity

Procedia PDF Downloads 45

Authors: Hafiz Muhammad Tayyab Bhatti, Munazza Usmani

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One of nature's most destructive occurrences, floods do immense damage to communities and economic losses. Nigeria country, specifically southern Nigeria, is known for being prone to flooding. Even though periodic flooding occurs in Nigeria frequently, the floods of 2022 were the worst since those in 2012. Flood vulnerability analysis and mapping are still lacking in this region due to the very limited historical hydrological measurements and surveys on the effects of floods, which makes it difficult to develop and put into practice efficient flood protection measures. Remote sensing and Geographic Information Systems (GIS) are useful approaches to detecting, determining, and estimating the flood extent and its impacts. In this study, NOAA VIIR has been used to extract the flood extent using the flood water fraction data and afterward fused with GIS data for some zonal statistical analysis. The estimated possible flooding areas are validated using satellite imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS). The goal is to map and studied flood extent, flood hazards, and their effects on the population, schools, and health facilities for each state of Nigeria. The resulting flood hazard maps show areas with high-risk levels clearly and serve as an important reference for planning and implementing future flood mitigation and control strategies. Overall, the study demonstrated the viability of using the chosen GIS and remote sensing approaches to detect possible risk regions to secure local populations and enhance disaster response capabilities during natural disasters.

Keywords: flood hazards, remote sensing, damage assessment, GIS, geospatial analysis

Procedia PDF Downloads 109

Authors: Saja M. Nabat Al-Ajrash, Charles Browning, Rose Eckerle, Li Cao

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A process that utilizes a combination of additive manufacturing (AM), a preceramic polymer, and a chopped carbon fiber precursorto fabricate Silicon Carbon/ Carbon fibers (SiC/C) composites have been developed. The study has shown a promising, cost-effective, and efficient route to fabricate complex SiC/C composites using additive manufacturing. A key part of this effort was the mapping of the material’s microstructure through the thickness of the composite. Microstructural features in the pyrolyzed composites through the successive AM layers, such as defects, crystal size and their distribution, interatomic spacing, chemical bonds, were investigated using high-resolution scanning and transmission electron microscopy. As a result, the microstructure developed in SiC/C composites after printing, cure, and pyrolysis has been successfully mapped through the thickness of the derived composites. Dense and nearly defect-free parts after polymer to ceramic conversion were observed. The ceramic matrix composite displayed three coexisting phases, including silicon carbide, silicon oxycarbide, and turbostratic carbon. Lattice fringes imaging and X-Ray Diffraction analysis showed well-defined SiC and turbostratic carbon features. The cross-sectional mapping of the printed-then-pyrolyzed structures has confirmed consistent structural and chemical features within the internal layers of the AM parts. Noteworthy, however, is that a crust-like area with high crystallinity has been observed in the first and last external layers. Not only do these crust-like regions have structural characteristics distinct from the internal layers, but they also have elemental distributions different than the internal layers.

Keywords: SiC, preceramic polymer, additive manufacturing, ceramic

Procedia PDF Downloads 58

Authors: Elhussaien Elshiekh

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A study was performed to management and compare radiation doses and image quality during Lumbar spine PA and Lumbar spine LAT, x- ray radiography using Computed Radiography (CR) and Digital Radiography (DR). Standard exposure factors such as kV, mAs and FFD used for imaging the Lumbar spine anthropomorphic phantom obtained from average exposure factors that were used with CR in five radiology centres. Lumbar spine phantom was imaged using CR and DR systems. Entrance surface air kerma (ESAK) was calculated X-ray tube output and patient exposure factor. Images were evaluated using visual grading system based on the European Guidelines on Quality Criteria for diagnostic radiographic images. The ESAK corresponding to each image was measured at the surface of the phantom. Six experienced specialists evaluated hard copies of all the images, the image score (IS) was calculated for each image by finding the average score of the Six evaluators. The IS value also was used to determine whether an image was diagnostically acceptable. The optimum recommended exposure factors founded here for Lumbar spine PA and Lumbar spine LAT, with respectively (80 kVp,25 mAs at 100 cm FFD) and (75 kVp,15 mAs at 100 cm FFD) for CR system, and (80 kVp,15 mAs at100 cm FFD) and (75 kVp,10 mAs at 100 cm FFD) for DR system. For Lumbar spine PA, the lowest ESAK value required to obtain a diagnostically acceptable image were 0.80 mGy for DR and 1.20 mGy for CR systems. Similarly for Lumbar spine LAT projection, the lowest ESAK values to obtain a diagnostically acceptable image were 0.62 mGy for DR and 0.76 mGy for CR systems. At standard kVp and mAs values, the image quality did not vary significantly between the CR and the DR system, but at higher kVp and mAs values, the DR images were found to be of better quality than CR images. In addition, the lower limit of entrance skin dose consistent with diagnostically acceptable DR images was 40% lower than that for CR images.

Keywords: image quality, dosimetry, radiation protection, optimization, digital radiography, computed radiography

Procedia PDF Downloads 36

Authors: Abdalla Mansour, Dan Brown, Adel Helmy, Rikin Trivedi, Mathew Guilfoyle

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Introduction: Diagnosing delayed cerebral ischaemia (DCI) following aneurysmal subarachnoid haemorrhage (SAH) can be challenging, particularly in poor-grade patients. Objectives: This study sought to assess the value of routine CTP in identifying (or excluding) DCI and in guiding management. Methods: Eight-year retrospective neuroimaging study at a large UK neurosurgical centre. Subjects included a random sample of adult patients with confirmed aneurysmal SAH that had a CTP scan during their inpatient stay, over a 8-year period (May 2014 - May 2022). Data collected through electronic patient record and PACS. Variables included age, WFNS scale, aneurysm site, treatment, the timing of CTP, radiologist report, and DCI management. Results: Over eight years, 916 patients were treated for aneurysmal SAH; this study focused on 466 patients that were randomly selected. Of this sample, 181 (38.84%) had one or more CTP scans following brain aneurysm treatment (Total 318). The first CTP scan in each patient was performed at 1-20 days following ictus (median 4 days). There was radiological evidence of DCI in 83, and no reversible ischaemia was found in 80. Findings were equivocal in the remaining 18. Of the 103 patients treated with clipping, 49 had DCI radiological evidence, in comparison to 31 of 69 patients treated with endovascular embolization. The remaining 9 patients are either unsecured aneurysms or non-aneurysmal SAH. Of the patients with radiological evidence of DCI, 65 had a treatment change following the CTP directed at improving cerebral perfusion. In contrast, treatment was not changed for (61) patients without radiological evidence of DCI. Conclusion: CTP is a useful adjunct to clinical assessment in the diagnosis of DCI and is helpful in identifying patients that may benefit from intensive therapy and those in whom it is unlikely to be effective.

Keywords: SAH, vasospasm, aneurysm, delayed cerebral ischemia

Procedia PDF Downloads 50

Authors: Mary M. Park

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Hollywood has had a long and enduring history of showcasing the United States military to civilian audiences, and the portrayals of soldiers in films have had a definite impact on the civilian perception of the US military. The growing gap between the civilian population and the military in the US has led to certain stereotypes of military personnel to proliferate, especially in the area of militarized masculinity, which has often been harmful to the psychological and spiritual wellbeing of military personnel. Examining Hollywood's portrayal of soldiers can serve to enhance our understanding of how civilians may be influenced in their perception of military personnel. Moreover, it can provide clues as to how male military personnel may also be influenced by Hollywood films as they form their own military identity. The post 9/11 era has seen numerous high budget films lionizing a particular type of soldier, the 'warrior-hero', who adheres to a traditional form of hegemonic masculinity and exhibits traits such as physical strength, bravery, stoicism, and an eagerness to fight. This paper examines how the portrayal of the 'warrior-hero' perpetuates a negative stereotype that soldiers are a blend of superheroes and emotionless robots and, therefore, inherently different from civilians. This paper examines the portrayal of militarized masculinity in three of the most successful war films of the post-9/11 era; Black Hawk Down (2001), The Hurt Locker (2008), and American Sniper (2014). The characters and experiences of the soldiers depicted in these films are contrasted with the lived experiences of soldiers during the Iraq and Afghanistan wars. Further, there is an analysis of popular films depicting ancient warriors, such as Troy (2004) and 300 (2007), which were released during the early years of the War on Terror. This paper draws on the concept of hegemonic militarised masculinity by leading scholars and feminist international relations theories on militarized masculinity. This paper uses veteran testimonies collected from a range of public sources, as well as previous studies on the link between traditional masculinity and war-related mental illness. This paper concludes that the seemingly exclusive portrayal of soldiers as 'warrior-heroes' in films in the post-9/11 era is misleading and damaging to civil-military relations and that the reality of the majority of soldiers' experiences is neglected in Hollywood films. As civilians often believe they are being shown true depictions of the US military in Hollywood films, especially in films that portray real events, it is important to find the differences between the idealized fictional 'warrior-heroes' and the reality of the soldiers on the ground in the War on Terror.

Keywords: civil-military relations, gender studies, militarized masculinity, social pyschology

Procedia PDF Downloads 107

Authors: Benhammadi Hocine, Djamel Boubaya, Chaffai Hicham

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Meskiana Area is characterized by a semi-arid climate where the water supply for irrigation and industry is not sufficient as the priority goes for domestic use. To meet the increasing population growth and development, the authorities have considered building a new water retaining structure on some major temporary water streams. For this purpose Chebabta site on Oued Meskiana was chosen as the future dam site. It is large enough to store the desired volume of water. This study comes to investigate the conditions of the site and the adequacy of the ground as a foundation for the projected dam. The conditions of the site include the geological structure and mainly the presence of discontinuities in the formation on which the dam will be built, the nature of the lithologies under the foundation and the future lake, and the presence of any hazard. This site characterization is usually carried out using different methods in order to highlight any underground buried problematic structure. In this context, the different geophysical technics remain the most used ones. Three geophysical methods were used in the case of the Chebabta dam site, namely, electric survey, seismic refraction, and tomography. The choice of the technics and the location of the scan line was made on the basis of the available geological data. In this sense, profiles have been established on both banks of Oued Meskiana. The obtained results have allowed a better characterization of the geological structure, defining the limit between the surface cover and the bedrock, which is, in other words, the limit between the weathered zone and the bedrock. Their respective thicknesses were also determined by seismic refraction and electrical resistivity sounding. However, the tomography imaging technic has succeeded in positioning a fault structure passing through the right bank of the wadi.

Keywords: dam site, fault, geophysic, investigation, Meskiana

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Authors: I. D. Laryushin, V. A. Kostin, A. A. Silaev, N. V. Vvedenskii

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Generation of broadband intense terahertz (THz) radiation attracts reasonable interest due to various applications, such as the THz time-domain spectroscopy, the probing and control of various ultrafast processes, the THz imaging with subwavelength resolution, and many others. One of the most promising methods for generating powerful and broadband terahertz pulses is based on focusing two-color femtosecond ionizing laser pulses in gases, including ambient air. For this method, the amplitudes of terahertz pulses are determined by the free-electron current density remaining in a formed plasma after the passage of the laser pulse. The excitation of this residual current density can be treated as multi-wave mixing: Аn effective generation of terahertz radiation is possible only when the frequency ratio of one-color components in the two-color pulse is close to irreducible rational fraction a/b with small odd sum a + b. This work focuses on the optimal parameters (polarizations and intensities) of laser components for the strongest THz generation. The optimal values of parameters are found numerically and analytically with the use of semiclassical approach for calculating the residual current density. For frequency ratios close to a/(a ± 1) with natural a, the strongest THz generation is shown to take place when the both laser components have circular polarizations and equal intensities. For this optimal case, an analytical formula for the residual current density was derived. For the frequency ratios such as 2/5, the two-color ionizing pulses with circularly polarized components practically do not excite the residual current density. However, the optimal parameters correspond generally to specific elliptical (not linear) polarizations of the components and intensity ratios close to unity.

Keywords: broadband terahertz radiation, ionization, laser plasma, ultrashort two-color pulses

Procedia PDF Downloads 191