WENO schemes applied to the quasi-relativistic Vlasov--Maxwell model for laser-plasma interaction

In this paper we focus on WENO-based methods for the simulation of the 1D Quasi-Relativistic Vlasov--Maxwell (QRVM) model used to describe how a laser wave interacts with and heats a plasma by penetrating into it. We propose several non-oscillatory methods based on either Runge--Kutta (explicit) or Time-Splitting (implicit) time discretizations. We then show preliminary numerical experiments

Relation between the 0νββ and 2νββ nuclear matrix elements reexamined

We show that the dominant Gamow-Teller part, M^(0ν)_(GT), of the nuclear matrix element governing the neutrinoless ββ decay is related to the matrix element M^(2ν)_(cl) governing the allowed two-neutrino ββ decay. That relation is revealed when these matrix elements are expressed as functions of the relative distance r between the pair of neutrons that are transformed into a pair of protons in the ββ decay. Analyzing this relation allows us to understand the contrasting behavior of these matrix elements when A and Z is changed; while M^(0ν)_(GT) changes slowly and smoothly, M^(2ν) has pronounced shell effects. We also discuss the possibility of phenomenological determination of the M^(2ν)_(cl) and from them of the M^(0ν)_(GT)values from the experimental study of the β^± strength functions

Relation between the 0νββ0\nu\beta\beta and 2νββ2\nu\beta\beta nuclear matrix elements revisited

We show that the dominant Gamow-Teller part, $M^{0\nu}_{GT}$, of the nuclear matrix element governing the neutrinoless $\beta\beta$ decay is related to the matrix element $M^{2\nu}_{cl}$ governing the allowed two-neutrino $\beta\beta$ decay. That relation is revealed when these matrix elements are expressed as functions of the relative distance $r$ between the pair of neutrons that are transformed into a pair of protons in the $\beta\beta$ decay. Analyzing this relation allows us to understand the contrasting behavior of these matrix elements when $A$ and $Z$ is changed; while $M^{0\nu}_{GT}$ changes slowly and smoothly, $M^{2\nu}$ has pronounced shell effects. We also discuss the possibility of phenomenological determination of the $M^{2\nu}_{cl}$ and from them of the $M^{0\nu}_{GT}$ values from the experimental study of the $\beta^{\pm}$ strength functions

Mapping evapotranspiration variability over a complex oasis-desert ecosystem based on automated calibration of Landsat 7 ETM+ data in SEBAL

Fragmented ecosystems of the desiccated Aral Sea seek answers to the profound local hydrologically- and water-related problems. Particularly, in the Small Aral Sea Basin (SASB), these problems are associated with low precipitation, increased temperature, land use and evapotranspiration (ET) changes. Here, the utility of high-resolution satellite dataset is employed to model the growing season dynamic of near-surface fluxes controlled by the advective effects of desert and oasis ecosystems in the SASB. This study adapted and applied the sensible heat flux calibration mechanism of Surface Energy Balance Algorithm for Land (SEBAL) to 16 clear-sky Landsat 7 ETM+ dataset, following a guided automatic pixels search from surface temperature T-s and Normalized Difference Vegetation Index NDVI (). Results were comprehensively validated with flux components and actual ET (ETa) outputs of Eddy Covariance (EC) and Meteorological Station (KZL) observations located in the desert and oasis, respectively. Compared with the original SEBAL, a noteworthy enhancement of flux estimations was achieved as follows: - desert ecosystem ETa R-2 = 0.94; oasis ecosystem ETa R-2 = 0.98 (P < 0.05). The improvement uncovered the exact land use contributions to ETa variability, with average estimates ranging from 1.24 mm to 6.98 mm . Additionally, instantaneous ET to NDVI (ETins-NDVI) ratio indicated that desert and oasis consumptive water use vary significantly with time of the season. This study indicates the possibility of continuous daily ET monitoring with considerable implications for improving water resources decision support over complex data-scarce drylands

Toxin-antitoxin system

Bakterije su razvile iznimnu sposobnost prilagodbe na različite životne uvjete. Uz pomoć raznih sustava i mehanizama daju brz stanični odgovor na stresore, tretman antibiotikom, stanje gladi i ostale nepovoljne uvjete. Jedan takav sustav pronađen je u kromosomu mnogih bakterija, ali i u plazmidima i drugim pokretnim elementima. Sastoji se od dva gena od kojih jedan kodira otrov, a drugi protuotrov. Otrovi su proteini koji interferiraju s vitalnim procesima, čime inhibiraju rast ili uzrokuju smrt stanice. Aktivnost otrova reguliraju protuotrovi koji ih direktno ili indirektno inhibiraju. S obzirom na to kakvim mehanizmom protuotrov djeluje na otrov, razlikujemo šest tipova sustava otrov-protuotrov. Sustavi otrovprotuotrov tipa II imaju i mehanizam transkripcijske autoregulacije, koji je reguliran omjerom otrov: protuotrov. Stanični signali poput (p)ppGpp i proteini koji sudjeluju u staničnom odgovoru na stres također mogu regulirati transkripciju sustava otrov-protuotrov. Sustavi otrovprotuotrov koji se nalaze na plazmidima i drugim pokretnim elementima sudjeluju u stabilizaciji istih preko PSK mehanizma, dok oni na kromosomu imaju ulogu u eng. abortive infection i eng. persister formation. Glavni modelni organizam u istraživanju sustava otrov-protuotrov je soj gamaproteobakterije E. coli K-12. Sustavi otrov-protuotrov pokazali su se kao mogući uzrok sve češćeg neuspjelog tretmana antibioticima. Razlog tome je perzistentno stanje koje omogućava bakterijama da se nakon tretmana antibiotikom ponovno razvije normalno rastuća populacija. U tijeku su istraživanja novih vrsta lijekova koji bi spriječili nastanak perzistentnog stanja. Međutim, i dalje nije razjašnjeno koja je točno veza između određenih sustava otrov-protuotrov i neke biološke funkcije, odnosno kada i kako točno će neki sustav reagirati na određene uvjete.During the course of their evolution, bacteria have developed an astounding ability to adapt to a wide variety of living conditions. Various cellular systems and mechanisms ensure rapid response to different stressors, antibiotics, starvation and other unfavourable conditions. One such system has been discovered both in chromosomal DNA and in mobile elements of bacteria. It's loci consist of two genes: one encodes a toxin, and the other encodes a cognate antitoxin. Toxins are proteins that interfere with vital cullular functions to inhibit bacterial growth, and can even cause apoptosis. Antitoxin control their cognate toxin through direct interactions, or through transcriptional and translational regulation of expression. Six types of these system have been described based on the nature of the antitoxin and how it inhibits the activity of the toxin protein. Transcriptional autoregulation of toxin-antitoxin (TA) modules is particularly prevalent among type II TA modules and is based on a T:A ratio. Transcription of TA modules can also be regulated by celullar signals such as (p)ppGpp and SOS signaling proteins. Some TA modules can prevent the loss of plasmids or other mobile elements from bacterial cultures through a mechanism known as PSK. TA modules found in chromosomal DNA of bacteria could be involved in abortive infection and persister formation mechanism. E. coli K-12 is the main model organims in research of TA system. Increasingly appreciated reason that antibiotics fail is because the bacteria use TA system to evade antibiotic exposure by persistent mechanism. Once relieved, the persisters can revert back to the actively growing state and repopulate the original population. Given the pressing need for new antibiotics, novel approaches that target TA systems and the processes that regulate them are warranted. One of the problems is that despite significant efforts, it has remained unclear how the molecular features and activities of TA modules are translated into biological function

Keeping the Wolves at Bay: Antitoxins of Prokaryotic Type II Toxin-Antitoxin Systems

In their initial stages of discovery, prokaryotic toxin-antitoxin (TA) systems were confined to bacterial plasmids where they function to mediate the maintenance and stability of usually low- to medium-copy number plasmids through the post-segregational killing of any plasmid-free daughter cells that developed. Their eventual discovery as nearly ubiquitous and repetitive elements in bacterial chromosomes led to a wealth of knowledge and scientific debate as to their diversity and functionality in the prokaryotic lifestyle. Currently categorized into six different types designated types I–VI, type II TA systems are the best characterized. These generally comprised of two genes encoding a proteic toxin and its corresponding proteic antitoxin, respectively. Under normal growth conditions, the stable toxin is prevented from exerting its lethal effect through tight binding with the less stable antitoxin partner, forming a non-lethal TA protein complex. Besides binding with its cognate toxin, the antitoxin also plays a role in regulating the expression of the type II TA operon by binding to the operator site, thereby repressing transcription from the TA promoter. In most cases, full repression is observed in the presence of the TA complex as binding of the toxin enhances the DNA binding capability of the antitoxin. TA systems have been implicated in a gamut of prokaryotic cellular functions such as being mediators of programmed cell death as well as persistence or dormancy, biofilm formation, as defensive weapons against bacteriophage infections and as virulence factors in pathogenic bacteria. It is thus apparent that these antitoxins, as DNA-binding proteins, play an essential role in modulating the prokaryotic lifestyle whilst at the same time preventing the lethal action of the toxins under normal growth conditions, i.e., keeping the proverbial wolves at bay. In this review, we will cover the diversity and characteristics of various type II TA antitoxins. We shall also look into some interesting deviations from the canonical type II TA systems such as tripartite TA systems where the regulatory role is played by a third party protein and not the antitoxin, and a unique TA system encoding a single protein with both toxin as well as antitoxin domains.Work supported by Grants CSD2008/00013 (to ME and WTC), and BIO2015-69085-REDC and BIO2013-49148-C2-2-R (to ME) from the Spanish Ministry of Economy and Competitiveness; PRPUM grant CG011-2014 (to CCY) from the Malaysian Ministry of Higher Education.Peer reviewedPeer Reviewe

Retrospective Investigation of Enteric Illnesses in Pet Animals

Recording and analysis of data are key elements to understand the epidemiology of various infectious and zoonotic diseases such as enteric pathogens and conditions. In this study, the clinical records of Alhelal Alazraq veterinary clinic in Tripoli were investigated for enteric diseases and illnesses in cats and dogs during the period of 2010–2015. The diagnostic and therapeutic guidelines within the Libyan veterinary system were also assessed and discussed based on the retrieved information and records. A total of 859 cases representing 528 (61%) from cats and 331 (39%) from dogs were retrieved and analysed using descriptive analysis. The cases were originated from five major areas from the center of Tripoli and the surrounding areas. Of these, 835/859 (97%) cases adopted antimicrobial based therapies and administered various antibiotic classes mainly and respectively using penicillin (652; 78%) and trimethoprim-sulfamethoxazole (229; 27%). The current study is the first retrospective investigation that analysed clinical and medical information from a major veterinary clinic in Libya. Diagnostic and therapeutic guidelines in the veterinary settings in Libya should be carefully reviewed and addressed. Retrospective studies and research programmes that monitor and investigate the occurrences of zoonotic and emerging pathogens particularly in relation to antimicrobial resistance are warranted in the Libyan health and medical system

Optical communication with semiconductor laser diodes

A 25 megabit/sec direct detection optical communication system that used Q=4 PPM signalling was constructed and its performance measured under laboratory conditions. The system used a single-mode AlGaAs laser diode transmitter and low noise silicon avalanche photodiode (APD) photodetector. Comparison of measured performance with the theoretical revealed that modeling the APD output as a Gaussian process under conditions of negligible background radiation and low (less than 10 to the -12 power A) APD bulk leakage currents leads to substantial underestimates of optimal APD gain to use and overestimates of system bit error probability. A procedure is given to numerically compute system performance which uses the more accurate Webb's Approximation of the exact Conradi distribution for the APD ouput signal that does not require excessive amounts of computer time (a few minutes of VAX 8600 CPU time per system operating point). Examples are given which illustrate the breakdown of the Gaussian approximation in assessing system performance. This system achieved a bit error probability of 10 to the -6 power at a received signal energy corresponding to an average of 60 absorbed photons/bit and optimal APD gain of 700