Edge-Terminated AlGaN/GaN/AlGaN Multi-Quantum Well Impact Avalanche Transit Time Sources for Terahertz Wave Generation.

In our pursuit of high-power terahertz (THz) wave generation, we propose innovative edge-terminated single-drift region (SDR) multi-quantum well (MQW) impact avalanche transit time (IMPATT) structures based on the AlxGa1-xN/GaN/AlxGa1-xN material system, with a fixed aluminum mole fraction of x = 0.3. Two distinct MQW diode configurations, namely p+-n junction-based and Schottky barrier diode structures, were investigated for their THz potential. To enhance reverse breakdown characteristics, we propose employing mesa etching and nitrogen ion implantation for edge termination, mitigating issues related to premature and soft breakdown. The THz performance is comprehensively evaluated through steady-state and high-frequency characterizations using a self-consistent quantum drift-diffusion (SCQDD) model. Our proposed Al0.3Ga0.7N/GaN/Al0.3Ga0.7N MQW diodes, as well as GaN-based single-drift region (SDR) and 3C-SiC/Si/3C-SiC MQW-based double-drift region (DDR) IMPATT diodes, are simulated. The Schottky barrier in the proposed diodes significantly reduces device series resistance, enhancing peak continuous wave power output to approximately 300 mW and DC to THz conversion efficiency to nearly 13% at 1.0 THz. Noise performance analysis reveals that MQW structures within the avalanche zone mitigate noise and improve overall performance. Benchmarking against state-of-the-art THz sources establishes the superiority of our proposed THz sources, highlighting their potential for advancing THz technology and its applications.

On-Chip Modification of Titanium Electrothermal Characteristics by Joule Heating: Application to Terahertz Microbolometer.

This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance ~14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of -0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiOx) semiconducting phase on the Ti phase (~85% purity) deposited initially, further to the heating. Formation of TiOx during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity.

Achieving Ultrawide Tunability in Monolithically Fabricated Si Nanoresonator Devices.

Nanoresonators are powerful and versatile tools promising to revolutionize a wide range of technological areas by delivering unparalleled performance in physical, chemical, biological sensing, signal and information processing, quantum computation, etc., via their high-frequency resonant vibration and rich dynamic behavior. Having the ability to tune the resonance frequency and dynamic behavior at the application stage promises further improvement in their effectiveness and enables novel applications. However, achieving significant room-temperature tunability in conventional (monolithically fabricated) nanoresonators is considered challenging. Here we demonstrate ultrawide electrostatic tuning (∼70%) of (initial) resonance-frequency (∼7% V-1) at room temperature in a monolithically fabricated ultrathin Si nanoresonator (width ∼ 40 nm, length ∼ 200 µm) device. Extreme electrostatic tuning of nonlinear behavior is also demonstrated by canceling the cubic-nonlinear coefficient and subsequently flipping its sign. Thus, these results are expected to provide remarkable operational flexibility and new capabilities to microfabricated resonators, which will benefit many technological areas.

Severe Hypoglycaemia in an Elderly Patient With Alzheimer's Dementia and Type 2 Diabetes Mellitus: A Case Report.

A 78-year-old diabetic patient was admitted with unexplained refractory hypoglycaemia. He was taking gliclazide and metformin and had good glycaemic control. He was suspected to have a sulfonylurea overdose, and intravenous 10% dextrose failed to correct hypoglycaemia. He was then treated with octreotide (a specific antidote to sulfonylurea), which corrected his low blood sugar level. Intravenous dextrose and octreotide are often the drugs of choice for treating hypoglycaemia from sulfonylurea toxicity. A high index of suspicion is needed for early diagnosis of sulfonylurea overdose.

Refractory Hypotension in an 80-Year-Old Man: A Case Report.

This case report presents the management and diagnosis of an 80-year-old gentleman who presented to the Accident and Emergency Department with refractory hypotension, hypoglycemia, and hyponatremia. Initially diagnosed with sepsis and cellulitis, it was later discovered that the patient was suffering from an Addisonian crisis due to adrenal insufficiency induced by long-term steroid use for rheumatoid arthritis. Prompt administration of intravenous hydrocortisone and fluid resuscitation led to a significant improvement in the patient's condition. This case emphasizes the importance of considering adrenal insufficiency in patients with similar clinical presentations and highlights the critical role of early diagnosis and treatment.

Development and Analysis of Graphene-Sheet-Based GaAs Schottky Solar Cell for Enriched Efficiency.

Comparative studies of the 2D numerical modelling and simulation of graphene-based gallium arsenide and silicon Schottky junction solar cell are studied using TCAD tools. The performance of photovoltaic cells was examined while taking parameters, such as substrate thickness, relationship between transmittance and work function of graphene, and n-type doing concentration of substrate semiconduction. The area with the highest efficiency for photogenerated carriers was found to be located near the interface region under light illumination. The significant enhancement of power conversion efficiency was shown in the cell with a thicker carrier absorption Si substrate layer, larger graphene work function, and average doping in a silicon substrate. Thus, for improved cell structure, the maximum JSC = 4.7 mA/cm2, VOC = 0.19 V, and fill factor = 59.73% are found under AM1.5G, exhibiting maximum efficiency of 6.5% (1 sun). The EQE of the cell is well above 60%. This work reports the influence of different substrate thickness, work function, and N-type doping on the efficiency and characteristics of graphene-based Schottky solar cells.

'Is hearing believing?': A study of voices and beliefs in psychosis and trauma.

OBJECTIVE: This study compared voice characteristics and beliefs in participants diagnosed with post-traumatic stress disorder (PTSD) with dissociation, schizophrenia (SCZ) and both diagnoses of SCZ and PTSD. The relationship between dissociation and voice beliefs was also assessed. METHOD: We identified 56 participants meeting the diagnostic criteria for PTSD with dissociation, SCZ or both diagnoses (PTSD + SCZ) who also experienced auditory hallucinations. Measures included PTSD Symptoms Scales Interview (PSSI-5), Psychotic Symptoms Rating Scale (PSYRAT), Clinician Administered Dissociative States Scale (CADSS), Beliefs about Voices Questionnaire (BAVQ) and Positive and Negative Syndrome Scale (PANSS). RESULTS: Beliefs about voices were similar across diagnostic groups. Participants with SCZ were more likely to attribute their voices to an external origin, and participants with dual diagnosis were less able to control their voices. The PTSD-only group scored higher in dissociation scores than either the SCZ-only or dual diagnosis group. Malevolent voice appraisals correlated with dissociation scores only in the dual diagnosis group. CONCLUSIONS: This research supports the hypothesis that voice beliefs are similar across diagnoses of PTSD and SCZ. However, differences in voice characteristics, emotional responses and relationship to dissociation may need to be considered in the psychological management of voices.

Visual phenomenology in schizophrenia and post-traumatic stress disorder: an exploratory study.

BACKGROUND: Visual experiences such as hallucinations are commonly reported by people with psychosis, psychological trauma and dissociative states, although questions remain about their similarities and differences. For diagnostic and therapeutic purposes, clinical research must better delineate and compare the characteristics of these experiences in post-traumatic stress disorder (PTSD) and in schizophrenia. AIMS: To compare visual phenomena and dissociation in participants with a primary psychotic illness and those with a trauma diagnosis. METHOD: A quantitative group design study comparing visual phenomena in three participant groups who also have a history of hearing voices: schizophrenia and no trauma history (n = 19), PTSD with dissociation (n = 17) and comorbid schizophrenia and PTSD (n = 20). Validated clinical measures included the North-East Visual Hallucination Interview, PTSD Symptoms Scale Interview, Clinician Administered Dissociative States Scale, Psychotic Symptoms Rating Scales and Positive and Negative Syndrome Scale. RESULTS: There was a remarkable similarity in visual experiences, including rates of complex visual hallucinations, between the three diagnostic groups. There were no significant differences in the severity or components of distress surrounding the visual experiences. Dissociation predicted visual hallucination severity for the comorbid schizophrenia and PTSD group, but not for PTSD or schizophrenia alone. CONCLUSIONS: Visual experiences in PTSD can include visual hallucinations that are indistinguishable from those experienced in schizophrenia. Multimodal hallucinations are frequently observed in both schizophrenia and PTSD. A model for visual hallucinations in PTSD is suggested, following two separate neurobiological pathways based on distinct responses to trauma.

Evolutionary Optimization of Machining Parameters Based on Surface Roughness in End Milling of Hot Rolled Steel.

Surface roughness measurements of machined parts are usually performed off-line after the completion of the machining operation. The objective of this work is to develop a surface roughness prediction method based on the processing of vibration signals during steel end milling operation performed on a vertical CNC machining center. The milling cuts were run under varying conditions (such as the spindle speed, feed rate, and depth of cut). This is a first step in the attempt to develop an online milling process monitoring system. The study presented here involves the analysis of vibration signals using statistical time parameters, frequency spectrum, and time-frequency wavelet decomposition. The analysis resulted in the extraction of 245 features that were used in the evolutionary optimization study to determine optimal cutting conditions based on the measured surface roughness of the milled specimen. Three feature selection methods were used to reduce the extracted feature set to smaller subsets, followed by binarization using two binarization methods. Three evolutionary algorithms-a genetic algorithm, particle swarm optimization and two variants, differential evolution and one of its variants, have been used to identify features that relate to the "best" surface finish measurements. These optimal features can then be related to cutting conditions (cutting speed, feed rate, and axial depth of cut). It is shown that the differential evolution and its variant performed better than the particle swarm optimization and its variants, and both differential evolution and particle swarm optimization perform better than the canonical genetic algorithm. Significant differences are found in the feature selection methods too, but no difference in performance was found between the two binarization methods.

Evaluation of Clustering Techniques to Predict Surface Roughness during Turning of Stainless-Steel Using Vibration Signals.

In metal-cutting processes, the interaction between the tool and workpiece is highly nonlinear and is very sensitive to small variations in the process parameters. This causes difficulties in controlling and predicting the resulting surface finish quality of the machined surface. In this work, vibration signals along the major cutting force direction in the turning process are measured at different combinations of cutting speeds, feeds, and depths of cut using a piezoelectric accelerometer. The signals are processed to extract features in the time and frequency domains. These include statistical quantities, Fast Fourier spectral signatures, and various wavelet analysis extracts. Various feature selection methods are applied to the extracted features for dimensionality reduction, followed by applying several outlier-resistant unsupervised clustering algorithms on the reduced feature set. The objective is to ascertain if partitions created by the clustering algorithms correspond to experimentally obtained surface roughness data for specific combinations of cutting conditions. We find 75% accuracy in predicting surface finish from the Noise Clustering Fuzzy C-Means (NC-FCM) and the Density-Based Spatial Clustering Applications with Noise (DBSCAN) algorithms, and upwards of 80% accuracy in identifying outliers. In general, wrapper methods used for feature selection had better partitioning efficacy than filter methods for feature selection. These results are useful when considering real-time steel turning process monitoring systems.

Tunable graphene nanopatch antenna design for on-chip integrated terahertz detector arrays with potential application in cancer imaging.

Aim: Further to our reports on chip-integrable uncooled terahertz microbolometer arrays, compatible with medium-scale semiconductor device fabrication processes, the possibility of the development of chip-integrable medical device is proposed here. Methods: The concept of graphene-based nanopatch antennas with design optimization by the finite element method (FEM) is explored. The high-frequency structure simulator (HFSS) utilized fine FEM solver for analyzing empirical mode decomposition preprocessing and for modeling and simulating graphene antennas. Results: Graphene nanopatch antennas exhibited tunable features with varying patch dimensions and dependence on substrate material permittivity. Conclusion: This work implements reconfigurable graphene nanopatch antenna compatible with terahertz microbolometer arrays. This design concept further develops on-chip medical devices for possible screening of cancer cell with terahertz image processing.

A Review of the Relationship of the Cerebrospinal Fluid Changes During the Dysregulation of Parathyroid Hormone With Psychiatric or Neurological Manifestations.

It is established that normal calcium and vitamin D concentrations are maintained in the body through parathyroid hormone (PTH), a signaling molecule secreted from parathyroid glands. A massive role is played by PTH in increasing calcium levels when they are extremely low in the body through different mechanisms. The dysregulation of this hormone is due to either over functioning of the gland (hyperparathyroidism) or compromised functioning in hypoparathyroidism. A detailed review was done to identify if any changes are happening in the cerebrospinal fluid (CSF) due to any pathology causing the parathormone to be dysregulated enough to, in turn, cause any further pathology in the nervous system. This may then lead to various disabling neuropsychiatric features. The calcium and vitamin D abnormalities are both directly and indirectly connected to psychiatric features like delusions, schizophrenia, disabled cognition, psychosis, coma, mania, and depression of all kinds. Moreover, their irregularities are also linked to Alzheimer's. During these manifestations, the CSF is altered concentration-wise, where elevated calcium levels inside are observed during different studies. Despite PTH's indirect connection to the CSF modifications, their association hasn't been potently proven yet, considering more observational studies should be conducted in humans and for a more extended period, along with bigger and greater numbers of CSF samples. Suppose there is a possibility of the link of CSF alterations to PTH. In that case, we can consider a pronounced increase of CSF calcium or PTH as a risk factor for debilitating neuropsychiatric diseases. In this review, the possible correlation of CSF and PTH has been discussed.

A Retrospective Analysis of Intracranial Pressure Monitoring and Outcomes in Adults after Severe Traumatic Brain Injury at Kaiser Permanente Trauma Centers.

BACKGROUND: The role of intracranial pressure (ICP) monitoring in improving outcomes after severe traumatic brain injury especially at level II trauma centers remains controversial. A retrospective analysis was undertaken to assess the impact of ICP monitoring on mortality and long-term functional outcome in adults after severe traumatic brain injury at level II trauma centers. METHODS: The data were extracted from the Kaiser Permanente trauma database. Inclusion criteria were adults (≥ 18 years) with severe traumatic brain injury (Glasgow Coma Scale score, < 9) admitted to 2 level II trauma centers in Northern California from 2014 to 2019. RESULTS: Of 199 patients, 58 (29.1%) underwent ICP monitoring. The monitored subgroup was significantly younger (< 65 years), had lower Glasgow Coma Scale scores (3-5), underwent cranial procedures (craniotomy or decompressive craniectomy) more often, and had greater injury severity scores (≥ 15). Despite monitored patients being more severely injured, there was no significant difference in mortality or 6-month favorable outcomes between monitored and nonmonitored patients, including patients who underwent cranial procedures. Increased monitoring frequency and reduction in overall mortality was seen throughout the study period yet with a parallel reduction in both groups. CONCLUSION: ICP monitoring may not impact in-patient mortality or long-term outcomes at level II trauma centers. Improved outcomes may be more related to identifying patients who may benefit from ICP-guided therapy rather than simply increasing the overall use of it. Last, our pattern of care and outcomes are comparable to level I trauma centers and our findings may serve as a benchmark for future studies.

BCG Vaccine, A Ray of Hope in Treating Severe Acute Respiratory Syndrome (SARS).

In December 2019 in China, the Severe Acute Respiratory Syndrome - Corona Virus - 2 (SARS-CoV-2) (also 2019 nCoV) was first discovered. Later, WHO declared that SARS-CoV-2 was responsible for Coronavirus Disease 2019 (COVID-19). The round, elliptical or pleomorphic shape of the 2019-nCoV is 60-140 nm in diameter. It comprises a single stranded genome of RNA that comprises 29891 nucleotides, a lipid shell and spike protein, envelops membrane, and hemagglutinin- esterase (HE) proteins. Several therapeutic approaches have been proposed to combat this disease as this disease became global pandemic. Bacillus Calmette-Guérin (BCG) vaccine could be another approach and at present, it is the only TB prevention vaccine approved. Both TB and COVID-19 cause severe pneumonia. In this review, we have tried to correlate the pathophysiology of both these disease condition. In this review, we also have shown the history and current BCG practice throughout the world and it is hypothesized that the countries which strictly maintained and made mandatory call to recommend BCG vaccination are relatively less affected by COVID-19 pandemic. When BCG is exposed to a subsequent viral infection, it is allowed to lead to cross-reactive T cell responses, which result in increased activity of Cluster of differentiation (CD) 4 + and Cluster of differentiation (CD) 8 + T cells and this may be a ray of hope in treating the SARS infection.

An Outlook on the Impact of HIV Infection and Highly Active Antiretroviral Therapy on the Cardiovascular System - A Review.

HIV has been related to various cardiovascular pathologies in both adults and children. Highly active antiretroviral therapy (HAART) has been effective in subduing viral replication and improving immunity thereby reducing the effects of HIV both in AIDS and other chronic diseases related to the virus. Complications related to HAART have been reported with metabolic disorders and cardiac effects seen based on the therapy. HIV and HAART have shown to have direct effects on the cardiovascular system, and more public awareness and medical knowledge are required on this subject. This literature review tries to shed some light on the role of HIV and HAART in the cardiovascular manifestations seen in HIV-infected individuals.

Neuroplasticity Improves Bipolar Disorder: A Review.

Bipolar disorder (BD) is known for impairments in neurotrophic and neuroprotective processes, which translate into emotional and cognitive deficits affecting various brain regions. Using its neuroplastic properties, lithium, thus far, is the mood stabilizer used to amend the pathophysiological imbalance in BD. Neuroplasticity has gained massive popularity in the research department in the past decade, yet it lacks direct effort in changing the protocol through which physicians treat BD. Physical activity alongside cognitive therapy is theorized to produce long-term changes in the executive control network due to the assimilation of new neurons, amendment of emotional lability through hippocampal neurogenesis, and strengthening the stability of frontosubcortical and prefrontolimbic brain regions via neurogenesis. This review aims to provide an incentive for utilizing neuroplastic mechanisms concerning impairments dispensed by BD.

Transdermal Nicotine as a Treatment Option for Ulcerative Colitis: A Review.

Ulcerative colitis (UC) is primarily a disease of non-smokers or ex-smokers. Since there have been previous claims of the beneficial effects of transdermal nicotine, researchers studied its efficacy to include it in the treatment regimen: to prevent remissions and as maintenance therapy. This review aims to evaluate the efficacy of transdermal nicotine as a treatment option for mild to moderately active ulcerative colitis. We shortlisted 22 articles after a careful analysis and elimination process. These articles were reviewed and analyzed, and it was found that transdermal nicotine in combination with conventional therapy was more beneficial than individual treatment with either. Further controlled studies evaluating the appropriate dosage for remission and maintenance treatment needs to be done.

Role of Cannabis in the Incidence of Myocardial Infarction: A Review.

Legalizing cannabis use in various states in the United States has caused increased substance abuse, mostly among young people. There are very little data focussing on marijuana use and myocardial infarction (MI) incidence. The objective of the study is to analyze the published papers for cannabis-induced MI and derive a strong relation between cannabis use and MI and understand the pathophysiology. An online search was conducted in PubMed, Google Scholar, and PubMed Central to find relevant publications examining patients who developed MI due to cannabis use. Out of 32 articles that were identified for this review, 17 are case reports, one is a letter to the editor, eight are observational studies, and six are review articles. Many studies have proposed different mechanisms by which cannabis affects the body. Our study shows that marijuana can precipitate MI even if it is used for the first time. Limited data is available to comment on the mortality of patients after cannabis-induced MI. These findings highlight the necessity for public awareness to prevent the ill-effects of cannabis, especially for teenagers and older people.

Performance Comparison of SOI-Based Temperature Sensors for Room-Temperature Terahertz Antenna-Coupled Bolometers: MOSFET, PN Junction Diode and Resistor.

Assuming that the 0.6-µm silicon-on-insulator (SOI) complementary metal-oxide-semiconductor (CMOS) technology, different Si-based temperature sensors such as metal-oxide-semiconductor field-effect transistor (MOSFET) (n-channel and p-channel), pn-junction diode (with p-body doping and without doping), and resistors (n+ or p+ single crystalline Si and n+ polycrystalline Si) were designed and characterized for its possible use in 1-THz antenna-coupled bolometers. The use of a half-wave dipole antenna connected to the heater end was assumed, which limited the integrated temperature sensor/heater area to be 15 × 15 µm. Our main focus was to evaluate the performances of the temperature sensor/heater part, and the optical coupling between the incident light and heater via an antenna was not included in the evaluation. The electrothermal feedback (ETF) effect due to the bias current was considered in the performance estimation. A comparative analysis of various SOI bolometers revealed the largest responsivity (Rv) of 5.16 kV/W for the n-channel MOSFET bolometer although the negative ETF in MOSFET reduced the Rv. The noise measurement of the n-channel MOSFET showed the NEP of 245 pW/Hz1/2, which was more than one order of magnitude smaller than that of the n+ polycrystalline Si resistive bolometer (6.59 nW/Hz1/2). The present result suggests that the n-channel MOSFET can be a promising detector for THz applications.