Giant Terahertz Birefringence in an Ultrathin Anisotropic Semimetal.

Manipulating the polarization of light at the nanoscale is key to the development of next-generation optoelectronic devices. This is typically done via waveplates using optically anisotropic crystals, with thicknesses on the order of the wavelength. Here, using a novel ultrafast electron-beam-based technique sensitive to transient near fields at THz frequencies, we observe a giant anisotropy in the linear optical response in the semimetal WTe2 and demonstrate that one can tune the THz polarization using a 50 nm thick film, acting as a broadband wave plate with thickness 3 orders of magnitude smaller than the wavelength. The observed circular deflections of the electron beam are consistent with simulations tracking the trajectory of the electron beam in the near field of the THz pulse. This finding offers a promising approach to enable atomically thin THz polarization control using anisotropic semimetals and defines new approaches for characterizing THz near-field optical response at far-subwavelength length scales.

Improved temporal resolution in ultrafast electron diffraction measurements through THz compression and time-stamping.

We present an experimental demonstration of ultrafast electron diffraction (UED) with THz-driven electron bunch compression and time-stamping that enables UED probes with improved temporal resolution. Through THz-driven longitudinal bunch compression, a compression factor of approximately four is achieved. Moreover, the time-of-arrival jitter between the compressed electron bunch and a pump laser pulse is suppressed by a factor of three. Simultaneously, the THz interaction imparts a transverse spatiotemporal correlation on the electron distribution, which we utilize to further enhance the precision of time-resolved UED measurements. We use this technique to probe single-crystal gold nanofilms and reveal transient oscillations in the THz near fields with a temporal resolution down to 50 fs. These oscillations were previously beyond reach in the absence of THz compression and time-stamping.

Demographics and characteristics of endoscopic findings among COVID-19 patients with upper gastrointestinal bleeding in a single centre.

INTRODUCTION: Novel coronavirus 19 disease (COVID-19) pandemic poses healthcare providers challenges in the endoscopic suite. It is unclear whether it affects the endoscopic manifestations of upper gastrointestinal (GI) bleeding. This retrospective study was done to review demographic data, site of lesions and need of interventions for those lesions. MATERIALS AND METHODS: Oesophagoduodenoscopy (OGDS) reports of COVID-19 patients with indication of upper GI bleeding from March 2021 to April 2022 were reviewed. Data of 35 patients were then analysed. RESULTS: Of the 35 patients, 8.6% (n = 3) were female and 91.4% (n = 32) were males. A total of 31.4% (n = 11) were below 50 years and 68.6% (n = 24) were 50 and above. 34.3% (n = 12) with lesions requiring endoscopic intervention, 34.3% (n = 12) with lesions not requiring endoscopic intervention, 31.4% (n = 11) has no significant stigmata of recent haemorrhage. Among subgroup requiring endoscopic intervention, 50% (n = 6) are non-variceal bleeding (NVUIB), and 50% (n = 6) are variceal bleeding (VUGIB). Among NVUGIB, 16.7% (n = 1) is gastric and duodenal angiodysplasia requiring argon plasma coagulation, 50% (n = 3) are duodenal F2A ulcer requiring thermoablation, 16.7% (n = 1) is gastric F2A ulcer requiring hemoclip, and 16.6% (n = 1) is Cameron's ulcer requiring hemoclip. Among VUGIB, 100% (n = 6) are oesophageal varices requiring endoscopic variceal banding (EVL). CONCLUSIONS: Lower proportion of NVUGIB among COVID-19 patients raises hypothesis on whether prothrombotic state of COVID-19 is a protective factor of NVUGIB. Studies with larger sample size are needed to establish significance.

Protective Effect of Topiramate against Diabetic Retinopathy and Computational Approach Recognizing the Role of NLRP3/IL-1ß/TNF-α Signaling.

The possible impact of topiramate against diabetic retinopathy (DREN) and its molecular mechanisms in relation to the nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome has not been studied before. Thus, in the present study, we aimed to utilize a computational approach to investigate the possible protective effect of topiramate on experimental DREN and explore its impact on NLRP3/interlukin-1ß signaling and brain-derived neurotrophic factor (BDNF) expression. Male albino mice were distributed to four experimental groups and assigned the following categorizations: (i) saline, (ii) diabetic, (iii) diabetic + topiramate 10 mg/kg and (iv) diabetic + topiramate 30 mg/kg. We observed shrinkage of total retinal thickness and elevation in retinal glutamate, malondialdehyde, NLRP3 and interlukin-1ß but decreased glutathione (GSH) levels in the diabetic mice. Additionally, retinal ultra-structures in the diabetic group showed abnormalities and vacuolations in the pigmented epithelium, the photoreceptor segment, the outer nuclear layer, the inner nuclear layer and the ganglion cell layer (GCL). Mice treated with topiramate 10 or 30 mg/kg showed downregulation in retinal malondialdehyde, NLRP3 and interlukin-1ß levels; improvements in the retinal pathologies; enhanced immunostaining for BDNF and improved ultra-structures in different retinal layers. Overall, the current results suggest topiramate as a neuroprotective agent for DREN, and future studies are warranted to further elucidate the mechanism of its protective action.

Widespread seafloor anoxia during generation of the Ediacaran Shuram carbon isotope excursion.

Reconstructing the oxygenation history of Earth's oceans during the Ediacaran period (635 to 539 million years ago) has been challenging, and this has led to a polarizing debate about the environmental conditions that played host to the rise of animals. One focal point of this debate is the largest negative inorganic C-isotope excursion recognized in the geologic record, the Shuram excursion, and whether this relic tracks the global-scale oxygenation of Earth's deep oceans. To help inform this debate, we conducted a detailed geochemical investigation of two siliciclastic-dominated successions from Oman deposited through the Shuram Formation. Iron speciation data from both successions indicate formation beneath an intermittently anoxic local water column. Authigenic thallium (Tl) isotopic compositions leached from both successions are indistinguishable from bulk upper continental crust (ε205 TlA ≈ -2) and, by analogy with modern equivalents, likely representative of the ancient seawater ε205 Tl value. A crustal seawater ε205 Tl value requires limited manganese (Mn) oxide burial on the ancient seafloor, and by extension widely distributed anoxic sediment porewaters. This inference is supported by muted redox-sensitive element enrichments (V, Mo, and U) and consistent with some combination of widespread (a) bottom water anoxia and (b) high sedimentary organic matter loading. Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.

Memantine mitigates ROS/TXNIP/NLRP3 signaling and protects against mouse diabetic retinopathy: Histopathologic, ultrastructural and bioinformatic studies.

Diabetic retinopathy (DRET) triggers vision loss in adults, however, little therapeutic options are existing. Memantine is an anti-Alzheimer drug that antagonizes the activity of glutamate at N-methyl-D-aspartate (NMDA) receptors. Glutamate and thioredoxin-interacting protein (TXNIP) are known to be overexpressed in diabetic retinas and can produce activation of NOD-like receptor protein 3 (NLRP3) with subsequent secretion of interlukin-1ß. This study repurposed memantine for its neuroprotective effect in experimental DRET and tested its impact on ROS/TXNIP/NLRP3. In addition, KEGG pathway database and STRING database identified the protein-protein interaction between glutamate receptors and TXNIP/NLRP3. Male Swiss albino mice received alloxan (180 mg/kg) to induce DRET. After 9 weeks, we divided the mice into groups: (a) saline, (ii) DRET, (iii and iv) DRET + oral memantine (5 or 10 mg per kg) for 28 days. Then, mice were euthanized, and eyeballs were removed. Retinal samples were utilized for biochemical, histopathological, and electron microscopy studies. Retinal levels of glutamate, TXNIP, NLRP3 and interlukin-1ß were estimated using ELISA technique as well as retinal malondialdehyde. Histopathological and ultrastructural examination demonstrated that oral memantine attenuated vacuolization and restored normal retinal cell layers. Moreover, memantine reduced TXNIP, NLRP3, interleukin-1ß and MDA concentrations. These results provide evidence demonstrating memantine' efficacy in alleviating DRET via suppressing reactive oxygen species/TXNIP/NLRP3 signaling cascade. Therefore, memantine might serve as a potential therapy for retinopathy after adequate clinical research.

The effect of COVID-19 pandemic on global stock markets: Return, volatility, and bad state probability dynamics.

This study investigates the impact of COVID-19 pandemic on stock returns, conditional volatility, conditional skewness and bad state probability. This study utilizes an asymmetric exponential generalized autoregressive conditional heteroscedasticity model to capture the asymmetric effect of positive and negative shocks (news) on conditional volatility. Using a sample consisting of international stock market indices in Brazil, China, Italy, India, Germany, Russia, Spain, United Kingdom, and United States, over the period from January 1, 2013 to December 31, 2020, we find unprecedented increases in conditional volatilities and bad state probabilities across all the markets. However, this impact is not symmetric across markets. Furthermore, we find that the negative affect of deaths is more pronounced, compared to the positive impact of recovered cases.

An empirical investigation of forecasting methods for ambulance calls - a case study.

A primary goal of emergency services is to minimise the response times to emergencies whilst managing operational costs. This paper is motivated by real data from the Welsh Ambulance Service which in recent years has been criticised for not meeting its eight-minute response target. In this study, four forecasting approaches (ARIMA, Holt Winters, Multiple Regression and Singular Spectrum Analysis (SSA)) are considered to investigate whether they can provide more accurate predictions to the call volume demand (total and by category) than the current approach on a selection of planning horizons (weekly, monthly and 3-monthly). Each method is applied to a training and test set and root mean square error (RMSE) and mean absolute percentage error (MAPE) error statistics are determined. Results showed that ARIMA is the best forecasting method for weekly and monthly prediction of demand and the long-term demand is best predicted using the SSA method.

Protective effect of metformin on rat diabetic retinopathy involves suppression of toll-like receptor 4/nuclear factor-k B expression and glutamate excitotoxicity.

Microvascular complications of diabetes mellitus are progressively significant reasons for mortality. Metformin (MET) is considered as the first-line therapy for type 2 diabetes patients, and may be especially beneficial in cases of diabetic retinopathy although the precise mechanisms of MET action are not fully elucidated. The current study was designed to inspect the antioxidant and modulatory actions of MET on DRET in streptozotocin-induced diabetic rats. The effect of MET on the toll-like receptor 4/nuclear factor kappa B (TLR4/NFkB), inflammatory burden and glutamate excitotoxicity was assessed. Twenty-four male rats were assigned to four experimental groups: (1) Vehicle group, (2) Diabetic control: developed diabetes by injection of streptozotocin (60 mg/kg, i.p.). (3&4) Diabetic + MET group: diabetic rats were left for 9 weeks without treatment and then received oral MET 100 and 200 mg/kg for 6 weeks. Retinal samples were utilized in biochemical, histological, immunohistochemical and electron microscopic studies. MET administration significantly decreased retinal level of insulin growth factor and significantly suppressed the diabetic induced increase of malondialdehyde, glutamate, tumor necrosis factor-α and vascular endothelial growth factor (VEGF). Further, MET decreased the retinal mRNA expression of NFkB, tumor necrosis factor-α and TLR4 in diabetic rats. The current findings shed the light on MET's efficacy as an adjuvant therapy to hinder the development of diabetic retinopathy, at least partly, via inhibition of oxidative stress-induced NFkB/TLR4 pathway and suppression of glutamate excitotoxicity.

Ulcerative colitis with concomitant primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is the most common liver disease and known hepatobiliary complication of ulcerative colitis (UC). Concomitant PSC in UC is associated with increased risk of rapid progression of primary sclerosing cholangitis, and malignancy including colon carcinoma as well as hepatobiliary carcinoma. We report a case of a 26-year-old woman who was diagnosed as ulcerative colitis during her second pregnancy. Her liver function test showed a significant elevation of alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) with other parameters being within normal range. A clinical suspicion of primary sclerosing cholangitis was then made. Magnetic resonance cholangiopancreticography (MRCP) revealed beaded appearance of the right and left intrahepatic ducts with focal narrowing seen at the ducts, suggestive of primary sclerosing cholangitis. She was subsequently started on oral Ursodeoxycholic acid (UDCA) with improvement in her liver function test within 3 weeks of initiation of treatment.

An epidemiological study of syphilis and predictors of treatment failure in University Malaya Medical Centre.

INTRODUCTION: There are limited studies on the epidemiology of syphilis in Malaysia. In this study we describe the clinical features and treatment outcomes of patients with syphilis attending a tertiary referral university hospital. METHODS: We retrospectively reviewed the case records of patients with positive serology findings for syphilis in University Malaya Medical Center (UMMC) from January 2010 to December 2015. Serological positivity was defined as having a positive rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) with a confirmatory positive Treponema pallidum particle agglutination assay (TPPA). Treatment outcomes were divided into two, success or failure. Demographic and clinical characteristics associated with predictors of treatment failure were assessed using statistical package for the social science (SPSS). This study also included a neurosyphilis descriptive sub-study. RESULTS: There were 637 patients identified with positive syphilis serology, but 258 patients were excluded as they did not meet the inclusion criteria. 379 patients were then taken for the demographic study; 14 patients (3.7%) were treated for neurosyphilis; 170 patients with complete data were included. In all 42/170 (24.7%) failed treatment, 12/170 (7.1%) had reinfection and 116/170 (68.2%) had treatment success. A final number of 158 patients were then taken and analyzed for predictors of treatment failure after excluding the 12 reinfection patients. Only low baseline RPR (<1:16) was found to be significant on multivariate logistic regression analysis (p value: 0.007, 95% CI: 1.42, 9.21). CONCLUSION: Most of the patients were HIV positive and from the MSM (Men who have sex with Men) population. Low baseline RPR titre is a predictor of treatment failure.

Parallel-plate waveguides for terahertz-driven MeV electron bunch compression.

We demonstrate the electromagnetic performance of waveguides for femtosecond electron beam bunch manipulation and compression with strong-field terahertz (THz) pulses. The compressor structure is a dispersion-free exponentially-tapered parallel-plate waveguide (PPWG) that can focus single-cycle THz pulses along one dimension. We show test results of the tapered PPWG structure using electro-optic sampling (EOS) at the interaction region with peak fields of at least 300 kV/cm, given 0.9 µJ of incoming THz energy. We also present a modified shorted design of the tapered PPWG for better beam manipulation and reduced magnetic field as an alternative to a dual-feed approach. As an example, we demonstrate that with 5 µJ of THz energy, the PPWG compresses a 2.5 MeV electron bunch by a compression factor of more than 4, achieving a bunch length of about 18 fs.

Oxidative stress caused by Basagran® herbicide is altered by salicylic acid treatments in peanut plants.

The present work was to study a protective role of salicylic acid (SA) on oxidative stress caused by Basagran® herbicide application. Two peanut cultivars (Arachis hypogaea cv. Giza 5 and Giza 6) with different sensitivities to the herbicide were monitored for their antioxidant responses to Basagran® and/or SA treatments. Two weeks after treatment, Basagran® lowered leaf pigments (Chlorophyll a, Chlorophyll b and total Carotenoids) but increased hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents indicating occurrence of lipid peroxidation and oxidative stress. Salicylic acid applied prior to low dose Basagran® lowered H2O2 and MDA contents in both G5 and G6. Except for SOD which is highly stimulated, POD, CAT and APX activities showed slight changes compared to control in leaves treated with Basagran® ± SA. The extracts tested by DPPH showed increase in total antioxidant activity by 4%-7% in SA + Basagran® treated leaves compared to control. The increased total antioxidant activity was related to the accumulation of amounts of phenolics as a protective action stimulated by SA. Alterations of antioxidant enzymatic system, accumulation of phenolics, increasing the total antioxidant activity by SA provide an evidence of protective action of SA in Basagran® detoxification.

Comparison of two simple models for prediction of short term mortality in patients after severe traumatic brain injury.

INTRODUCTION: The subscale motor score of Glasgow Coma Scale (msGCS) and the Abbreviated Injury Score of head region (HAIS) are validated prognostic factors in traumatic brain injury (TBI). The aim was to compare the prognostic performance of a HAIS-based prediction model including HAIS, pupil reactivity and age, and the reference prediction model including msGCS in emergency department (ED), pupil reactivity and age. METHODS: Secondary analysis of a prospective epidemiological study including patients after severe TBI (HAIS > 3) with follow-up from the time of accident until 14 days or earlier death was performed in Switzerland. Performance of prediction, based on accuracy of discrimination [area under the receiver-operating curve (AUROC)], calibration (Hosmer-Lemeshow test) and validity (bootstrapping with 2000 repetitions to correct) for optimism of the two prediction models were investigated. A non-inferiority approach was performed and an a priori threshold for important differences was established. RESULTS: The cohort included 808 patients [median age 56 {inter-quartile range (IQR) 33-71}, median motor part of GCS in ED 1 (1-6), abnormal pupil reactivity 29.0%] with a death rate of 29.7% at 14 days. The accuracy of discrimination was similar (AUROC HAIS-based prediction model: 0.839; AUROC msGCS-based prediction model: 0.826, difference of the 2 AUROC 0.013 (-0.007 to 0.037). A similar calibration was observed (Hosmer-Lemeshow X2 11.64, p = 0.168 vs. Hosmer-Lemeshow X2 8.66, p = 0.372). Internal validity of HAIS-based prediction model was high (optimism corrected AUROC: 0.837). CONCLUSIONS: Performance of prediction for short-term mortality after severe TBI with HAIS-based prediction model was non-inferior to reference prediction model using msGCS as predictor.

Neurologic Outcomes in Aortic Arch Repair With Frozen Elephant Trunk Versus 2-Stage Hybrid Repair.

BACKGROUND: We compared outcomes of single-stage hybrid aortic arch replacement (frozen elephant trunk) versus 2-stage hybrid repairs with primary open arch procedures followed by thoracic endovascular stenting. METHODS: This study reports a single-center retrospective review (2003 to 2016) of 118 patients undergoing hybrid repair of the aortic arch including 48 single-stage repairs versus 70 two-stage repairs. RESULTS: Single-stage repair was performed in 48 patients, including 31 (64.6%) men and 17 (35.4%) women with a mean age of 64 ± 11 years and a 2-stage procedure was performed in 70 patients, including 42 (60%) men and 28 (40%) women with a mean age of 65.67 ± 13.3 years (p = 0.46). More emergent single-stage procedures were performed in 23 of 48 (47.9%) patients versus 2-stage procedures in 8 of 70 (11.43%) patients (p < 0.001). Between the single- and 2-stage groups, there was no difference in stroke (6.25% [3 of 48] versus 14.28% [10 of 70]; p = 0.23), spinal cord ischemia (4.16% [2 of 48] versus 5.7% [4 of 70]; p = 1.0), or 30-day mortality rate: 8 of 48 (16.7%) patients versus a combined 30-day mortality rate of the 2-stage procedure of 14.8% (4 of 70 [5.7%] at the first stage and 5 of 55 [9.1%] at the second stage; p = 0.56), respectively. After exclusion of the 30-day mortality, midterm survival was 86% at 1 to 2 years for single-stage patients versus 80% at 1 year and 46% at 2 years for the 2-stage patients (p = 0.0019). CONCLUSIONS: Both single-stage and 2-stage hybrid arch replacements are effective approaches for treating complex aortic arch diseases. Early deaths and neurological outcomes in the single-stage group are comparable to those in the combined 2-stage group. Furthermore, in this series, patients who had a single-stage hybrid procedure had a higher survival rate at 2 years.

The influence of zinc on the blood serum of cadmium-treated rats through the rheological properties.

The blood rheological properties serve as an important indicator for the early detection of many diseases. This study aimed to investigate the influence of zinc (Zn) on blood serum of cadmium (Cd) intoxication-treated male rats through the rheological properties. The rheological parameters were measured in serum of control, Cd, and Cd+Zn groups at wide range of shear rates (225-1875 s(-1)). The rat blood serum showed a non-significant change in cadmium-treated rats' %torque and shear stress at the lower shear rates (200-600 s(-1)) while a significant increase was observed at the higher shear rates (650-1875 s(-1)) compared with the control. The rat blood serum viscosity increased significantly in the Cd-treated group at each shear rate compared with the control. The viscosity and shear rate exhibited a non-Newtonian behavior for all groups. The increase in blood serum viscosity in Cd-treated male rats might be attributed to destruction or changes in the non-clotting proteins, and other blood serum components. In Cd+Zn-treated rats, the rat blood serum viscosity values returned nearer to the control values at each shear rate. Our results confirmed that Zn displaced Cd or compete with the binding sites for Cd uptake.

Morphological and physiological changes in esterase and lipid peroxidation of two bean cultivars pre-soaked with potassium nitrate under salt stress.

Two broad bean cultivars (Vicia faba CV Nobaria3 and Vicia faba CV Sakha3) were obtained from Mallwi Agriculture Research Center, El Minia Governorate, Egypt. The seeds were divided into two groups, the first group soaked with distilled water, while the second group were soaked with 3 mM KNO3, respectively, for 4 hours. Seeds were sown and left to grow for 3 weeks then treated with different concentrations of NaCl (0.0, 40, 80, 120 and 160 mM) by top irrigation, then they left to grow further for 65 days from sowing. Plant samples were collected for some measurements: leaf area, plant height, root length, fresh and dry weight, photosynthetic pigments, carotenoids, soluble sugars, soluble proteins, total free amino acids, esterase enzyme, as well as MDA (malondialdehyde) content. Salinity reduced both fresh and dry weight in two broad bean cultivars, this reduction were more pronounced in Sakha3 than Nobaria3. Seed pre-soaking with KNO3resulted in enhancement of fresh and dry weight production in both cultivars especially at 40 mM NaCl. Photosynthetic pigments were substantially affected by salt treatment while the carotenoids were increased, seed pre-soaking with KNO3improved these components. The soluble sugars, amino acids as well as soluble proteins showed various responses with increasing salinity in the cultivars, seed pre-soaking with KNO3has improved these parameters to some extent. The shoots of two cultivars exhibited significant accumulation of MDA, compared to roots exposed to the highest salinity levels. Pre-soaking seeds with KNO3did not improve MDA in shoots but enhanced it in roots, however, in most cases still lower than the absolute control. The assessment of the esterase isozyme profiles on 7.5% native polyacrylamide gel revealed the presence of 13 isoforms in two faba bean plants in response to KNO3pre-soaking and treatments with different concentrations of NaCl.

Graphene-based tunable hyperbolic metamaterials and enhanced near-field absorption.

We investigate a novel implementation of hyperbolic metamaterial (HM) at far-infrared frequencies composed of stacked graphene sheets separated by thin dielectric layers. Using the surface conductivity model of graphene, we derive the homogenization formula for the multilayer structure by treating graphene sheets as lumped layers with complex admittances. Homogenization results and limits are investigated by comparison with a transfer matrix formulation for the HM constituent layers. We show that infrared iso-frequency wavevector dispersion characteristics of the proposed HM can be tuned by varying the chemical potential of the graphene sheets via electrostatic biasing. Accordingly, reflection and transmission properties for a film made of graphene-dielectric multilayer are tunable at terahertz frequencies, and we investigate the limits in using the homogenized model compared to the more accurate transfer matrix model. We also propose to use graphene-based HM as a super absorber for near-fields generated at its surface. The power emitted by a dipole near the surface of a graphene-based HM is increased dramatically (up to 5 × 10(2) at 2 THz), furthermore we show that most of the scattered power is directed into the HM. The validity and limits of the homogenized HM model are assessed also for near-fields and show that in certain conditions it overestimates the dipole radiated power into the HM.

Is myocutaneous flap alone sufficient for reconstruction of chest wall osteoradionecrosis?

OBJECTIVES: This study was carried out to determine whether the myocutaneous flap, alone, is sufficient to reconstruct a chest wall defect after osteoradionecrosis and provide satisfactory stability to the chest wall. METHODS: This study involved five patients who were subjected to post-mastectomy radiotherapy as a treatment for breast cancer. Excision of the ulcer and all the necrotic ribs, with preservation of the parietal pleura and reconstruction with the latissimus dorsi flap, was done without the use of either an artificial prosthesis or autologous rib to reconstruct the chest wall defect. RESULTS: Clinical and radiological follow-up showed no complications regarding respiratory impairment or pleural complications. CONCLUSIONS: The use of myocutaneous flap in patients with chest wall defect following osteoradionecrosis is satisfactory to cover the chest wall defect and provide satisfactory stability to the chest wall.