Spin waves in ultrathin ferromagnetic overlayers

The influence of a non-magnetic metallic substrate on the spin wave excitations in ultrathin ferromagnetic overlayers is investigated for different crystalline orientations. We show that spin wave dumping in these systems occur due to the tunneling of holes from the substrate into the overlayer, and that the spin wave energies may be considerably affected by the exchange coupling mediated by the substrate.Comment: RevTeX 4, 7 pages, 5 figures; submitted to Phys. Rev.

Network Diversity Multiple Access in Rayleigh Fading Correlated Channels with Imperfect Channel and Collision Multiplicity Estimation

Network diversity multiple access or NDMA is the family of algorithms with the highest potential throughput in the literature of signal-processing-assisted random access. NDMA uses the concept of protocol-induced retransmissions to create an adaptive source of physical (PHY) layer diversity. This adaptive diversity is used to resolve packet collisions (via signal separation) without the explicit need (or as a complement) of a multiple antenna receiver. This paper proposes a further improvement on the modelling of NDMA by considering the effects of imperfect channel and collision multiplicity estimation. In addition, this work considers channel correlation between consecutive retransmissions (i.e., temporal correlation). Conventionally, the analysis of NDMA assumes that any error in the collision multiplicity estimation translates into the loss of all contending packets. This is an optimistic assumption because even when the multiplicity has been correctly estimated, errors can still occur. On the other hand, it is also pessimistic because correct reception can also occur when the multiplicity has been incorrectly estimated. This paper presents a more detailed study of the performance of the protocol considering these more specific reception cases

Enzymatic hydrolysis of esters from 2-carboxy-6- methoxy-2,3-dihydrobenzofuran acid

In this work we describe the results of the enzymatic hydrolysis of esters from 2-carboxy-6-methoxy-2,3-dihydrobenzofuran acid using Candida antarctica lipase supported on acrylic resin, with enantiomeric excesses ranging between 80 to 99%

COVID-19, función suprarrenal y corticosteroides

La pandemia por SARS-nCoV-2 elevó muchos interrogantes sobre su efecto en múltiples sistemas. Los datos han sido tomados de infecciones previas por coronavirus, estudios epidemiológicos observacionales y explicaciones que demuestran plausibilidad biológica. El compromiso que produce el virus SARS-nCoV-2 no escapa al campo de la endocrinología y en este documento se consigna la relación que existe entre la función suprarrenal, su respuesta a los procesos infecciosos y el uso de corticosteroides en la COVID-19

Palaeoenvironment of Eocene prodelta in Spitsbergen recorded by the trace fossil Phycosiphon incertum

Ichnological, sedimentological and geochemical analyses were conducted on the Eocene Frysjaodden Formation in order to interpret palaeoenvironment prodelta sediments in the Central Basin of Spitsbergen. Phycosiphon incertum is the exclusive ichnotaxon showing differences in size, distribution, abundance and density, and relation to laminated/bioturbated intervals. Large P. incertum mainly occur dispersed, isolated and randomly distributed throughout the weakly laminated/non-laminated intervals. Small P. incertum occur occasionally in patches of several burrows within laminated intervals or as densely packed burrows in thin horizons in laminated intervals or constituting fully bioturbated intervals that are several centimetres thick. Ichnological changes are mainly controlled by oxygenation, although the availability of benthic food cannot be discarded. Changes in oxygenation and rate of sedimentation can be correlated with the registered variations in the Bouma sequence of the distal turbiditic beds within prodeltal shelf sediments.Funding for this research was provided by Project CGL2012-33281 (Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain), Project RYC-2009-04316 (Ramón y Cajal Programme) and Projects RNM-3715 and RNM-7408 and Research Group RNM-178 (Junta de Andalucía). The authors benefited from a bilateral agreement between the universities of Granada and Oslo, supported by the University of Granada

An Adaptive Mutation in Enterococcus faecium LiaR Associated with Antimicrobial Peptide Resistance Mimics Phosphorylation and Stabilizes LiaR in an Activated State

The cyclic antimicrobial lipopeptide daptomycin (DAP) triggers the LiaFSR membrane stress response pathway in enterococci and many other Gram-positive organisms. LiaR is the response regulator that, upon phosphorylation, binds in a sequence-specific manner to DNA to regulate transcription in response to membrane stress. In clinical settings, non-susceptibility to DAP by Enterococcus faecium is correlated frequently with a mutation in LiaR of Trp73 to Cys (LiaRW73C). We have determined the structure of the activated E. faecium LiaR protein at 3.2 Å resolution and, in combination with solution studies, show that the activation of LiaR induces the formation of a LiaR dimer that increases LiaR affinity at least 40-fold for the extended regulatory regions upstream of the liaFSR and liaXYZ operons. In vitro, LiaRW73C induces phosphorylation-independent dimerization of LiaR and provides a biochemical basis for non-susceptibility to DAP by the upregulation of the LiaFSR regulon. A comparison of the E. faecalis LiaR, E. faecium LiaR, and the LiaR homolog from Staphylococcus aureus (VraR) and the mutations associated with DAP resistance suggests that physicochemical properties such as oligomerization state and DNA specificity, although tuned to the biology of each organism, share some features that could be targeted for new antimicrobials

Directrices para zonificación, uso y manejo del desierto La Tatacoa

El Desierto de la Tatacoa se caracteriza por sus condiciones climáticas y botánicas de zonas tropicales áridas y semiáridas, cuyas tierras están dedicadas principalmente a la ganadería extensiva y en menor proporción a la agricultura. Sin embargo, sobresale por su riqueza paleontológica y sus áreas de refugio para la diversidad de aves en el alto Magdalena,  los atractivos naturales y aspectos sugerentes para el ecoturismo; éstos no son protegidos adecuadamente y en consecuencia, se ha considerado necesario proponer algunas directrices para su zonificación con fines de uso y manejo

Barriers to completing oral glucose tolerance testing in women at risk of gestational diabetes.

AIM: Complications of gestational diabetes (GDM) can be mitigated if the diagnosis is recognized. However, some at-risk women do not complete antenatal diagnostic oral glucose tolerance testing (OGTT). We aimed to understand reasons contributing to non-completion, particularly to identify modifiable factors. METHODS: Some 1906 women attending a tertiary UK obstetrics centre (2018-2019) were invited for OGTT based on risk-factor assessment. Demographic information, test results and reasons for non-completion were collected from the medical record. Logistic regression was used to analyse factors associated with non-completion. RESULTS: Some 242 women (12.3%) did not complete at least one OGTT, of whom 32.2% (n = 78) never completed testing. In adjusted analysis, any non-completion was associated with younger maternal age [≤ 30 years; odds ratio (OR) 2.3, 95% confidence interval (CI) 1.6-3.4; P < 0.001], Black African ethnicity (OR 2.7, 95% CI 1.2-5.5; P = 0.011), lower socio-economic status (OR 0.9, 95% CI 0.8-1.0; P = 0.021) and higher parity (≥ 2; OR 1.8, 95% CI 1.1-2.8; P = 0.013). Non-completion was more likely if testing indications included BMI ≥ 30 kg/m2 (OR 1.7, 95% CI 1.1-2.4; P = 0.009) or family history of diabetes (OR 2.2, 95% CI 1.5-3.3; P < 0.001) and less likely if the indication was an ultrasound finding (OR 0.4, 95% CI 0.2-0.9; P = 0.035). We identified a common overlapping cluster of reasons for non-completion, including inability to tolerate test protocol (21%), social/mental health issues (22%), and difficulty keeping track of multiple antenatal appointments (15%). CONCLUSIONS: There is a need to investigate methods of testing that are easier for high-risk groups to schedule and tolerate, with fuller explanation of test indications and additional support for vulnerable groups.Catherine Aiken is supported by an Isaac Newton Trust[12.21(a)]/Wellcome Trust ISSF [105602/Z/14/Z]/ University of Cambridge Joint Research Grant. Claire Meek is supported by the Diabetes UK Harry Keen intermediate clinical fellowship (17/0005712) and the European Foundation for the Study of Diabetes/ Novo Nordisk Foundation Futures Leader’s Award (NNF19SA058974). Juliet Usher-Smith is supported by a Cancer Research UK Prevention Fellowship (C55650/A21464)