Interband electron Raman scattering in a quantum wire in a transverse magnetic field

Electron Raman scattering (ERS) is investigated in a parabolic semiconductor quantum wire in a transverse magnetic field neglecting by phonon-assisted transitions. The ERS cross-section is calculated as a function of a frequency shift and magnetic field. The process involves an interband electronic transition and an intraband transition between quantized subbands. We analyze the differential cross-section for different scattering configurations. We study selection rules for the processes. Some singularities in the Raman spectra are found and interpreted. The scattering spectrum shows density-of-states peaks and interband matrix elements maximums and a strong resonance when scattered frequency equals to the "hybrid" frequency or confinement frequency depending on the light polarization. Numerical results are presented for a GaAs/AlGaAs quantum wire.Comment: 8 pages, 5 figure

Mel silvestre: qualidade para a valorização e competitividade da apicultura no Pantanal.

O presente trabalho teve-se o objetivo de avaliar, por meio de análises físico-químicas e sensoriais, a qualidade de 17 amostras de méis silvestres multiflorais de abelhas africanizadas (Apis mellifera L.), produzidos em escala experimental entre 2006 e 2007 na fazenda Nhumirim, Unidade Experimental da Embrapa Pantanal, localizada na sub-região da Nhecolândia do Pantanal, Corumbá-MSbitstream/item/161779/1/BP98.pd

Automatic paraphrasing tools: an unexpected consequence of addressing student plagiarism and the impact of COVID in distance education settings

Text matching tools employed to detect plagiarism are widely used in universities, but their availability may have pushed students to find ways to evade detection. One such method is the use of automatic paraphrasing software, where assignments can be rewritten with little effort required by students. This paper uses the search engine analytics methodology with data from SEMrush and Google Trends to estimate the level of interest in online automatic paraphrasing tools, focusing on the period 2016 to 2020 and the four countries: the USA, UK, Canada and Australia. The results show a concerning trend, with the number of searches for such tools growing during the period, especially during COVID-19, and notable increases observed during the months where assessment periods take place in universities. The method employed in this study opens up a new avenue of analysis to enrich and supplement the existing knowledge in the field of academic integrity research. The data obtained demonstrates that faculty should be alert for student use of automatic paraphrasing tools and that academic integrity interventions need to be in place across the sector to address this problem

Sedimentological and palaeohydrological characterization of Late Pleistocene and Holocene tufa mound palaeolakes using trenching methods in the Spanish Pyrenees

Lakes developed in the inner depressions of tufa mounds are rare geomorphic features and still poorly understood. Sedimentation in this unusual type of endorheic lake with a very restricted catchment area is highly sensitive to environmental and hydrological changes. The Isona tufa mound complex, north-eastern Iberian Peninsula, is associated with the discharge zone of a confined artesian aquifer and comprises 11 tufa mounds consisting of an annular rimstone enclosing a central depression filled with lake deposits. Data gathered from trenches excavated in four palaeolakes located within three different morphostratigraphic units permitted a precise analysis of the geometrical characteristics and stratigraphic relationships of the deposits and provided a sedimentation model for the Late Quaternary infilling of the spring-fed lakes. The work illustrates that trenches allow a precise characterization of the stratigraphic arrangements, lateral facies changes and deformation structures, which are not apparent in studies relying solely on borehole records, and facilitate sampling for dating and geochemical analyses. The five sedimentary facies described represent different evolutionary stages of the lakes, including: (i) carbonate-rich palustrine deposits probably related to periods with strong hydrological seasonality; (ii) massive highly bioturbated organic ooze; (iii) banded organic carbonate-rich facies associated with an increase in the regional effective moisture; (iv) finegrained quartz-rich aeolian/slope-wash sediments; and (v) colluvial facies deposited following the desiccation of the lakes located at higher altitudes. Geochemical and sedimentological analyses of the lacustrine sequences provided information on the palaeohydrological evolution of the Isona tufa mound complex and the palaeoenvironmental conditions of the area over the last 28 ka. Radiometric dating suggests that deposition occurred simultaneously at ca 22 ka in palaeolakes situated at different elevations. A drop in the piezometric level prompted by the opening of springs at lower altitudes probably caused the deactivation of the upper springs and the desiccation of the lakes. Arid conditions prevailed in the area during the Late Glacial and the early Holocene (28·0 to 8·5 ka BP). More humid conditions recorded from 8·5 to 4·2 ka and again since 1·7 ka are in accordance with palaeoenvironmental reconstructions available in the Western Mediterranean since the Last Glacial Maximum

Identifying the boundaries of sinkholes and subsidence areas via trenching and establishing setback distances

One of the most effective mitigation strategies in sinkhole areas is the exclusion of sinkholes and their vicinity to construction. The application of this preventive measure requires precise mapping of the boundaries of the areas affected by subsidence and the establishment of adequate setback distances, which is an important policy issue with significant economic implications. Through the investigation of several buried sinkholes in the mantled evaporite karst of the Ebro Valley by trenching, this work illustrates that the actual extent of the subsidence areas may be much larger than that inferred from surface mapping and geophysical surveys. The objective and accurate subsurface information acquired from trenches on the outer edge of the deformed ground revealed sinkhole radii 2–3 times larger than initially estimated, increasing one order of magnitude the sinkhole area. Trenches can therefore help to reduce mapping uncertainties and the size of setbacks. Moreover, the trenching technique, in combination with geochronological data and retrodeformation analyses, provides critical information on the subsidence phenomena and the characteristics of the sinkholes relevant to hazard assessment. Since recommended setback distances found in the existing literature are highly variable and rather arbitrary, we include a discussion here on the main factors that should be considered when defining setback zones for sinkholes

Selective Pressure by Rifampicin Modulates Mutation Rates and Evolutionary Trajectories of Mycobacterial Genomes

Resistance to the frontline antibiotic rifampicin constitutes a challenge to the treatment and control of tuberculosis. Here, we analyzed the mutational landscape of Mycobacterium smegmatis during long-term evolution with increasing concentrations of rifampicin, using a mutation accumulation assay combined with whole-genome sequencing. Antibiotic treatment enhanced the acquisition of mutations, doubling the genome-wide mutation rate of the wild-type cells. While antibiotic exposure led to extinction of almost all wild-type lines, the hypermutable phenotype of the ΔnucS mutant strain (noncanonical mismatch repair deficient) provided an efficient response to the antibiotic, leading to high rates of survival. This adaptative advantage resulted in the emergence of higher levels of rifampicin resistance, an accelerated acquisition of drug resistance mutations in rpoB (β RNA polymerase), and a wider diversity of evolutionary pathways that led to drug resistance. Finally, this approach revealed a subset of adaptive genes under positive selection with rifampicin that could be associated with the development of antibiotic resistance. IMPORTANCE Rifampicin is the most important first-line antibiotic against mycobacterial infections, including tuberculosis, one of the top causes of death worldwide. Acquisition of rifampicin resistance constitutes a major global public health problem that makes the control of the disease challenging. Here, we performed an experimental evolution assay under antibiotic selection to analyze the response and adaptation of mycobacteria, leading to the acquisition of rifampicin resistance. This approach explored the total number of mutations that arose in the mycobacterial genomes under long-term rifampicin exposure, using whole-genome sequencing. Our results revealed the effect of rifampicin at a genomic level, identifying different mechanisms and multiple pathways leading to rifampicin resistance in mycobacteria. Moreover, this study detected that an increase in the rate of mutations led to enhanced levels of drug resistance and survival. In summary, all of these results could be useful to understand and prevent the emergence of drug-resistant isolates in mycobacterial infections.This research was funded by MCIN/AEI/10.13039/501100011033, grant PID2020-112865RB-I00, and Instituto de Salud Carlos III, grant FIS PI17/00159 (ISCIII/FEDER, UE). E.C.-S. is the recipient of a PFIS predoctoral research fellowship (FI18/00036) cofinanced by the Instituto de Salud Carlos III and the European Social Fund. A.C.-G. acknowledges financial support from the Spanish State Research Agency, AEI/10.13039/501100011033, through the “Severo Ochoa” Program for Centers of Excellence in R&D (SEV-2013-0347, SEV-2017-0712). Editorial assistance was provided by Stuart L. Rulten. Statistical consultancy was provided by Applied Statistical Department-SGAI-CSIC.S

Is late-life dependency increasing or not? A comparison of the Cognitive Function and Ageing Studies (CFAS)

Background: Little is known about how dependency levels have changed between generational cohorts of older people. We estimated years lived in different care states at age 65 in 1991 and 2011 and new projections of future demand for care. Methods: Two population-based studies of older people in defined geographical areas conducted two decades apart (the Cognitive Function and Ageing Studies) provided prevalence estimates of dependency in four states: high (24-hour care); medium (daily care); low (less than daily); independent. Years in each dependency state were calculated by Sullivan’s method. To project future demand, the proportions in each dependency state (by age group and sex) were applied to the 2014 England population projections. Findings: Between 1991 and 2011 there were significant increases in years lived from age 65 with low (men:1·7 years, 95%CI 1·0-2·4; women:2·4 years, 95%CI 1·8-3·1) and high dependency (men:0·9 years, 95%CI 0·2-1·7; women:1·3 years, 95%CI 0·5-2·1). The majority of men’s extra years of life were independent (36%) or with low dependency (36%) whilst for women the majority were spent with low dependency (58%), only 5% being independent. There were substantial reductions in the proportions with medium and high dependency who lived in care homes, although, if these dependency and care home proportions remain constant in the future, further population ageing will require an extra 71,000 care home places by 2025. Interpretation: On average older men now spend 2.4 years and women 3.0 years with substantial care needs (medium or high dependency), and most will live in the community. These findings have considerable implications for older people’s families who provide the majority of unpaid care, but the findings also supply valuable new information for governments and care providers planning the resources and funding required for the care of their future ageing populations

What are the current and projected future cost and health-related quality of life implications of scaling up cognitive stimulation therapy?

Objectives: Cognitive stimulation therapy (CST) is one of the few non-pharmacological interventions for people living with dementia shown to be effective and cost-effective. What are the current and future cost and health-related quality of life implications of scaling-up CST to eligible new cases of dementia in England? // Methods/design: Data from trials were combined with microsimulation and macrosimulation modelling to project future prevalence, needs and costs. Health and social costs, unpaid care costs and quality-adjusted life years (QALYs) were compared with and without scaling-up of CST and follow-on maintenance CST (MCST). // Results: Scaling-up group CST requires year-on-year increases in expenditure (mainly on staff), but these would be partially offset by reductions in health and care costs. Unpaid care costs would increase. Scaling-up MCST would also require additional expenditure, but without generating savings elsewhere. There would be improvements in general cognitive functioning and health-related quality of life, summarised in terms of QALY gains. Cost per QALY for CST alone would increase from £12,596 in 2015 to £19,573 by 2040, which is below the threshold for cost-effectiveness used by the National Institute for Health and Care Excellence (NICE). Cost per QALY for CST and MCST combined would grow from £19,883 in 2015 to £30,906 by 2040, making it less likely to be recommended by NICE on cost-effectiveness grounds. // Conclusions: Scaling-up CST England for people with incident dementia can improve lives in an affordable, cost-effective manner. Adding MCST also improves health-related quality of life, but the economic evidence is less compelling

A two decade dementia incidence comparison from the Cognitive Function and Ageing Studies I and II.

Dramatic global increases in future numbers of people with dementia have been predicted. No multicentre population-based study powered to detect changes over time has reported dementia incidence. MRC Cognitive Function and Ageing Study (CFAS) undertook baseline interviews in populations aged 65+ years in England and Wales (1989-1994). Three areas (CFAS I) were selected for new sampling two decades later (2008-2011) with same geographical boundaries, sampling and approach methods (CFAS II). At 2 years CFAS I interviewed 5,156 (76% response) with 5,288 interviewed in CFAS II (74% response). Here we report a 20% drop in incidence (95% CI: 0-40%), driven by a reduction in men across all ages above 65. In the UK we estimate 209,600 new dementia cases per year. This study was uniquely designed to test for differences across geography and time. A reduction of age-specific incidence means that the numbers of people estimated to develop dementia in any year has remained relatively stable.CFAS II has been supported by the UK Medical Research Council (Research Grant: G06010220) and received additional support from the National Institute for Health Research (NIHR), comprehensive clinical research networks in West Anglia, Nottingham City and Nottinghamshire County NHS Primary Care trusts and the dementias and neurodegenerative disease research Network (DeNDRoN) in Newcastle. MRC CFAS I was funded by the MRC (Research Grant: G9901400) and the National Health Service (NHS). F.E.M. is supported by the MRC (Research Grant: U105292687). This research was done within the UK National Institute of Health Research collaboration for leadership in applied health research and care for Cambridgeshire and Peterborough (CLAHRC EoE), the Biomedical Research Centre infrastructures at Cambridge and Newcastle upon Tyne. We thank the participants, their families, the general practitioners and their staff, the primary care trusts and CCGs for their cooperation and support. We thank the CFAS II fieldwork interviewers at Cambridge, Nottingham and Newcastle for their valuable contribution. Funding was given by UK Medical Research Council.This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms1139

From cheek swabs to consensus sequences : an A to Z protocol for high-throughput DNA sequencing of complete human mitochondrial genomes

Background: Next-generation DNA sequencing (NGS) technologies have made huge impacts in many fields of biological research, but especially in evolutionary biology. One area where NGS has shown potential is for high-throughput sequencing of complete mtDNA genomes (of humans and other animals). Despite the increasing use of NGS technologies and a better appreciation of their importance in answering biological questions, there remain significant obstacles to the successful implementation of NGS-based projects, especially for new users. Results: Here we present an ‘A to Z’ protocol for obtaining complete human mitochondrial (mtDNA) genomes – from DNA extraction to consensus sequence. Although designed for use on humans, this protocol could also be used to sequence small, organellar genomes from other species, and also nuclear loci. This protocol includes DNA extraction, PCR amplification, fragmentation of PCR products, barcoding of fragments, sequencing using the 454 GS FLX platform, and a complete bioinformatics pipeline (primer removal, reference-based mapping, output of coverage plots and SNP calling). Conclusions: All steps in this protocol are designed to be straightforward to implement, especially for researchers who are undertaking next-generation sequencing for the first time. The molecular steps are scalable to large numbers (hundreds) of individuals and all steps post-DNA extraction can be carried out in 96-well plate format. Also, the protocol has been assembled so that individual ‘modules’ can be swapped out to suit available resources