Exponential distributions in Markov chain models for communication channels

A brief history of Markov chain models for communication channels is given. One such model, the most complicated devised to date, is discussed in more detail. For this model, some statistics are presented in terms of sums of exponential functions. As an example, error free runs of two of the numerous trophospheric channels for which we have chosen parameters are studied here

The development of a fullerene based hydrogen storage system

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objective was to evaluate hydrogen uptake by fullerene substrates and to probe the potential of the hydrogen/fullerene system for hydrogen fuel storage. As part of this project, the authors have completed and tested a fully automated, computer controlled system for measuring hydrogen uptake that is capable of handling both a vacuum of 1 x 10{sup -6} torr and pressures greater than 200 bars. The authors have first established conditions for significant uptake of hydrogen by fullerenes. Subsequently, hydrogenation and dehydrogenation of pure and catalyst-doped C60 was further studied to probe suitability for hydrogen storage applications. C60 {center_dot} H18.7 was prepared at 100 bar H2 and 400 C, corresponding to hydrogen uptake of 2.6 wt%. Dehydrogenation of C60 {center_dot} H18.7 was studied using thermogravimetric and powder x-ray diffraction analysis. The C60 {center_dot} H18.7 molecule was found to be stable up to 430 C in Ar, at which point the release of hydrogen took place simultaneously with the collapse of the fullerene structure. X-ray diffraction analysis performed on C60 {center_dot} H18.7 samples dehydrogenated at 454 C, 475 C, and 600 C showed an increasing volume fraction of amorphous material due to randomly oriented, single-layer graphine sheets. Evolved gas analysis using gas chromatography and mass spectroscopy confirmed the presence of both H{sub 2} and methane upon dehydrogenation, indicating decomposition of the fullerene. The remaining carbon could not be re-hydrogenated. These results provide the first complete evidence for the irreversible nature of fullerene hydrogenation and for limitations imposed on the hydrogenation/dehydrogenation cycle by the limited thermal stability of the molecular crystal of fullerene

Microbial rhodopsins on leaf surfaces of terrestrial plants

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 14 (2012): 140-146, doi:10.1111/j.1462-2920.2011.02554.x.The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 1026 microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454- pyrosequencing generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point toward the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.This work was supported in part by a grant from Bridging the Rift Foundation (O.B. & S.B.), Israel Science Foundation grant 1203/06 (O.B.), the Gruss-Lipper Family Foundation at MBL (O.M.F., S.B. & A.F.P.), a US-Israel Binational Science Foundation grant 2006324 (S.B.), and DOE National Institutes of Health Grant R37GM27750, Department of Energy Grant DE-FG02-07ER15867, and endowed chair AU-0009 from the Robert A. Welch Foundation (J.L.S.)

SYK expression level distinguishes control from BRCA1-mutated lymphocytes

Tamar Zahavi,1,2,* Amir Sonnenblick,1,3,* Yael Shimshon,2 Luna Kadouri,1 Tamar Peretz,1 Asher Y Salmon,1,* Mali Salmon-Divon,2,* 1Sharett Institute of Oncology, Hadassah Hebrew University Medical Center, Jerusalem, Israel; 2Genomic Bioinformatics Laboratory, Department of Molecular Biology, Ariel University, Ariel, Israel; 3Sackler Faculty of Medicine, Sourasky Medical Center, Institute of Oncology, Tel Aviv University, Tel Aviv, Israel *These authors contributed equally to this work Background: About 5%–10% of breast cancer and 10%–15% of ovarian cancer are hereditary. BRCA1 and BRCA2 are the most common germline mutations found in both inherited breast and ovarian cancers. Once these mutations are identified and classified, a course of action to reduce the risk of developing either ovarian or breast cancer – including surveillance and surgery – is carried out. Purpose: The purpose of the current research is to characterize the gene expression differences between healthy cells harboring a mutation in BRCA1/2 genes and normal cells. This will allow detection of candidate genes and help identify women who carry functional BRCA1/2 mutations, which cannot always be detected by the available sequencing methods, for example, carriers of mutations found in regulatory sequences of the genes. Materials and methods: Our cohort consisted of 50 healthy women, of whom 24 were individuals with BRCA1 or BRCA2 heterozygous mutations and 26 were non-carrier controls. RNA purified from non-irradiated lymphocytes of nine BRCA1/2 mutation carriers versus four control mutation-negative individuals was utilized for RNA-Seq analysis. The selected RNA-Seq transcripts were validated, and the levels of spleen tyrosine kinase (SYK) mRNA were measured by using real-time quantitative polymerase chain reaction. Results: Differences in gene expression were found when comparing untreated lymphocytes of BRCA1/2 mutation carriers and controls. Among others, the SYK gene was identified as being differently expressed for BRCA1/2 mutation carriers. The expression level of SYK was significantly higher in untreated healthy lymphocytes of BRCA1 heterozygote carriers compared with controls, regardless of irradiation. In contrast to normal tissues, in cancerous breast tissues, the expression levels of the BRCA1 and SYK genes were not intercorrelated. Conclusion: Collectively, our observations demonstrate that SYK may prove to be a good candidate for better diagnosis, treatment, and prevention of BRCA1 mutation-associated breast cancer. Keywords: RNA-Seq, breast cancer susceptibility, peripheral bloo

A remote access mixed reality teaching ward round

Background Heterogeneous access to clinical learning opportunities and inconsistency in teaching is a common source of dissatisfaction among medical students. This was exacerbated during the COVID‐19 pandemic, with limited exposure to patients for clinical teaching. Methods We conducted a proof‐of‐concept study at a London teaching hospital using mixed reality (MR) technology (HoloLens2™) to deliver a remote access teaching ward round. Results Students unanimously agreed that use of this technology was enjoyable and provided teaching that was otherwise inaccessible. The majority of participants gave positive feedback on the MR (holographic) content used (n = 8 out of 11) and agreed they could interact with and have their questions answered by the clinician leading the ward round (n = 9). Quantitative and free text feedback from students, patients and faculty members demonstrated that this is a feasible, acceptable and effective method for delivery of clinical education. Discussion We have used this technology in a novel way to transform the delivery of medical education and enable consistent access to high‐quality teaching. This can now be integrated across the curriculum and will include remote access to specialist clinics and surgery. A library of bespoke MR educational resources will be created for future generations of medical students and doctors to use on an international scale