Quantum transport at the Dirac point: Mapping out the minimum conductivity from pristine to disordered graphene

The phase space for graphene's minimum conductivity $\sigma_\mathrm{min}$ is mapped out using Landauer theory modified for scattering using Fermi's Golden Rule, as well as the Non-Equilibrium Green's Function (NEGF) simulation with a Monte Carlo sampling over impurity distributions. The resulting `fan diagram' spans the range from ballistic to diffusive over varying aspect ratios ($W/L$), and bears several surprises. {The device aspect ratio determines how much tunneling (between contacts) is allowed and becomes the dominant factor for the evolution of $\sigma_{min}$ from ballistic to diffusive regime. We find an increasing (for $W/L>1$) or decreasing ($W/L<1$) trend in $\sigma_{min}$ vs. impurity density, all converging around $128q^2/\pi^3h\sim 4q^2/h$ at the dirty limit}. In the diffusive limit, the {conductivity} quasi-saturates due to the precise cancellation between the increase in conducting modes from charge puddles vs the reduction in average transmission from scattering at the Dirac Point. In the clean ballistic limit, the calculated conductivity of the lowest mode shows a surprising absence of Fabry-P\'{e}rot oscillations, unlike other materials including bilayer graphene. We argue that the lack of oscillations even at low temperature is a signature of Klein tunneling

Beware the Anomalous Portal Vein

Portal vein thrombosis is an unusual potential complication of liver resection. In our case it was due to ligation of the right branch of the portal vein during right hepatectomy in a patient without portal vein bifurcation. Hepatic angiography can delineate this abnormality and influence the choice of surgical management

A Case Report on Longitudinal Collection of Tumour Biopsies for Gene Expression-Based Tumour Microenvironment Analysis from Pancreatic Cancer Patients Treated with Endoscopic Ultrasound Guided Radiofrequency Ablation.

BACKGROUND: Most patients with pancreatic ductal adenocarcinoma (PDAC) are metastatic at presentation with dismal prognosis warranting improved systemic therapy options. Longitudinal sampling for the assessment of treatment response poses a challenge for validating novel therapies. In this case study, we evaluate the feasibility of collecting endoscopic ultrasound (EUS)-guided longitudinal fine-needle aspiration biopsies (FNABs) from two PDAC patients and conduct gene expression studies associated with tumour microenvironment changes associated with radiofrequency ablation (RFA). METHODS: EUS-guided serial/longitudinal FNABs of tumour were collected before and after treatment from two stage III inoperable gemcitabine-treated PDAC patients treated with targeted RFA three times. Biopsies were analysed using a custom NanoString panel (144 genes) consisting of cancer and cancer-associated fibroblast (CAFs) subtypes and immune changes. CAF culture was established from one FNAB and characterised by immunofluorescence and immunoblotting. RESULTS: Two-course RFA led to the upregulation of the CD1E gene (involved in antigen presentation) in both patients 1 and 2 (4.5 and 3.9-fold changes) compared to baseline. Patient 1 showed increased T cell genes (CD4-8.7-fold change, CD8-35.7-fold change), cytolytic function (6.4-fold change) and inflammatory response (8-fold change). A greater than 2-fold upregulation of immune checkpoint genes was observed post-second RFA in both patients. Further, two-course RFA led to increased PDGFRα (4.5-fold change) and CAF subtypes B and C genes in patient 1 and subtypes A, B and D genes in patient 2. Patient 2-derived CAFs post-first RFA showed expression of PDGFRα, POSTN and MYH11 proteins. Finally, RFA led to the downregulation of classical PDAC subtype-specific genes in both patients. CONCLUSIONS: This case study suggests longitudinal EUS-FNAB as a potential resource to study tumour and microenvironmental changes associated with RFA treatment. A large sample size is required in the future to assess the efficacy and safety of the treatment and perform comprehensive statistical analysis of EUS-RFA-based molecular changes in PDAC

A Consistency Check of Concrete Compressive Strength using Pearson’s Correlation Coefficient

The efficiency of the concrete ready mix service provider is undoubtedly and has become a widespread trend among contractors in which facilitates and eliminated a large budget surplus in maintenance, operating costs and is preferred as it reflects more efficient asset utilization. However, the quality assurance of concrete supplied is always raised associated with the inconsistencies of concrete compressive strength at the age of 28 days. The objective(s) of this study are to determine the correlations between the compressive strength of ready mix concrete, to evaluate the consistencies of the results and to identify the irregular sources that lead to the inconsistencies. Based on the compressive strength values obtained from the existing experimental data using different concrete mixes from the batching plant, a statistical analysis was conducted. A total of 90 concrete cubes specimens were attained from 15 concrete batches. A correlation analysis was conducted using the Pearson Correlation calculation to check the consistency of concrete compressive strength. The calculation showed the Pearson correlation coefficient of this study is +0.990. This indicated that there are significant linear relationship exists between the concrete compressive strength and the density of concrete batches which is positively high. In conclusion, the analysis reveals that the design of ready mix concrete compressive strength is in high consistencies and acceptable in practices for the proposed mix design to the contractor. Doi: 10.28991/cej-2021-03091672 Full Text: PD

MULTI-HAZARD RISK ASSESSMENT OF QURUMBAR VALLEY, GHIZER, GILGIT BALTISTAN, PAKISTAN

Being located in a seismically active zone, these mountain valleys are exposed to different hydro-meteorological hazards like rockfall, debris flow, landslide, ice avalanches, and glacial lake outburst flood (GLOFs).&nbsp; The present study is to investigate different multi-hazards and their prevailing risk in the particular area of Qurumbar valley Ishkoman. In the mid-nineteen and twenty centuries at least six devastating glacial lake outburst floods (GLOFs) has been recorded, initially, only the Qurumbar glacier was considered as the main cause of this outburst flood, later field investigation and interview from local inhabitant revealed that nine more tributary glacier are existing in the area. The recent outburst of flood in the Badswat area of Qurumbar Ishkoman is also considerable, submerging 12 houses and a stretch of roads. Apart from it, the physical vulnerability of the area is increasing, as new areas are being used for housing with the increase in population. The study area is exposed to several other natural hazards like rock fall, debris flows, ice avalanches, and bank erosion. The present study is based on quantitative and qualitative approaches in assistance with GIS/RS an emergent application. The following methodologies were adapted to gather the primary and secondary data for GIS/RS processing. The primary data comprises GIS data and procurement and development and field data. The field data contain ground-truthing /validation. The community-based Hazard Vulnerability Risk Assessment (HVRA) was also carried out to know about human perception. Secondary data has been collected from different literature. Both the data were put into GIS for the processing which gives us our final developmental tools in the form of maps. The hazard and risk map of the Qurumbar Ishkoman depict that flash floods, debris flow, bank erosion, and GLOFs account for major hazards in Qurumbar valley. It is concluded based on our outcomes i.e., hazard and risk maps that earthquake is the main hazard of the area while flash floods, GLOFs, debris flow, bank erosion and the bank collapsed are the main hazards of the area. It is very important to systematically integrate map information into the planning and management process which contributes to a safer environment