2,200 research outputs found
Активація м’язів плечового пояса та плеча людини в перебігу двосуглобових рухів руки, що виконуються при дії зовнішніх навантажень протилежних напрямів
У дослідах на чотирьох добровольцях досліджувалася координація центральних рухових команд (ЦРК), що керували повільними двосуглобовими рухами руки в горизонтальній площині. Як кореляти інтенсивності таких команд розглядались поточні амплітуди ЕМГ, відведених від шести м’язів плечового пояса і плеча й підданих повному випрямленню та низькочастотній фільтрації. Зокрема, досліджували залежність координації ЦРК від напрямку зовнішньої сили, яка прикладалася до дистальної частини передпліччя. Як виявилося, координація ЦРК істотно залежить від напрямку сили, що згинає ліктьовий суглоб. Згідно з результатами дослідження, ЕМГ певних м’язів у разі виконання двосуглобового руху може бути представлена як лінійна комбінація ЕМГ, зареєстрованих у перебігу послідовних односуглобових рухів в умовах пересування референтної точки кисті в ту ж саму точку операційного простору, що й при двосуглобовому русі. Отримані дані можуть вважатися підтвердженням принципу суперпозиції елементарних ЦРК під час виконання складних рухів кінцівок
High-level diversity of tailed phages, eukaryote-associated viruses, and virophage-like elements in the metaviromes of Antarctic soils
The metaviromes of two distinct Antarctic hyperarid desert soil communities have been characterized. Hypolithic communities,
cyanobacterium-dominated assemblages situated on the ventral surfaces of quartz pebbles embedded in the desert pavement,
showed higher virus diversity than surface soils, which correlated with previous bacterial community studies. Prokaryotic viruses
(i.e., phages) represented the largest viral component (particularly Mycobacterium phages) in both habitats, with an identical
hierarchical sequence abundance of families of tailed phages (Siphoviridae>Myoviridae>Podoviridae). No archaeal viruses
were found. Unexpectedly, cyanophages were poorly represented in both metaviromes and were phylogenetically distant from
currently characterized cyanophages. Putative phage genomes were assembled and showed a high level of unaffiliated genes,
mostly from hypolithic viruses. Moreover, unusual gene arrangements in which eukaryotic and prokaryotic virus-derived genes
were found within identical genome segments were observed. Phycodnaviridae and Mimiviridae viruses were the second-mostabundant
taxa and more numerous within open soil. Novel virophage-like sequences (within the Sputnik clade) were identified.
These findings highlight high-level virus diversity and novel species discovery potential within Antarctic hyperarid soils and may
serve as a starting point for future studies targeting specific viral groups.IS
Coupled-resonator optical waveguides: Q-factor and disorder influence
Coupled resonator optical waveguides (CROW) can significantly reduce light
propagation pulse velocity due to pronounced dispersion properties. A number of
interesting applications have been proposed to benefit from such slow-light
propagation. Unfortunately, the inevitable presence of disorder, imperfections,
and a finite Q value may heavily affect the otherwise attractive properties of
CROWs. We show how finite a Q factor limits the maximum attainable group delay
time; the group index is limited by Q, but equally important the feasible
device length is itself also limited by damping resulting from a finite Q.
Adding the additional effects of disorder to this picture, limitations become
even more severe due to destructive interference phenomena, eventually in the
form of Anderson localization. Simple analytical considerations demonstrate
that the maximum attainable delay time in CROWs is limited by the intrinsic
photon lifetime of a single resonator.Comment: Accepted for Opt. Quant. Electro
Identification of Peptide Ligands for Targeting to the Blood-Brain Barrier
PurposeTransport of drugs to the brain is limited by the blood-brain barrier. New, specific brain endothelium ligands can facilitate brain-specific delivery of drugs. MethodsWe used phage display in an in situ brain perfusion model to screen for new brain endothelium peptide ligands. ResultsTwo phage clones, displaying 15 amino acid-peptides (GLA and GYR) that were selected for brain binding in the mouse model, showed significant binding to human brain endothelium (hCMEC/D3), compared to a random control phage. This binding was not seen for other human endothelial cells (HUVEC). Binding to hCMEC/D3 cells was dose dependent. When phage GLA and GYR were individually perfused through the murine brain, their ability to bind to the brain was 6-fold (GLA) and 5-fold (GYR) higher than the control phage. When compared to lung perfusion, phage showed an 8.5-fold (GYR) and 48-fold (GLA) preference for brain over lung compared to the control. ConclusionsThese results indicate that two new peptide ligands have been identified that may be used for specific targeting of drugs to the blood-brain barrier
Dust-enshrouded Asymptotic Giant Branch Stars in the Solar Neighbourhood
A study is made of a sample of 58 dust-enshrouded Asymptotic Giant Branch
(AGB) stars (including 2 possible post AGB stars), of which 27 are carbon-rich
and 31 are oxygen-rich. These objects were originally identified by Jura &
Kleinmann as nearby (within about 1 kpc of the sun) AGB stars with high
mass-loss rates, greater than 1E-6 solar masses per year. Ground-based
near-infrared photometry, data obtained by IRAS and kinematic data from the
literature are combined to investigate the properties of these stars. The light
amplitude in the near-infrared is found to be correlated with period, and this
amplitude decreases with increasing wavelength. Statistical tests show that
there is no reason to suspect any difference in the period distributions of the
carbon- and oxygen-rich stars for periods less than 1000 days, and no
carbon-rich star has a period longer than 1000 days. The colours are consistent
with those of cool stars with evolved circumstellar dust-shells. Luminosities
and distances are estimated using a period-luminosity relation. Mass-loss
rates, estimated from the 60 micron fluxes, show a correlation with pulsation
period and is tightly correlated with the K-[12] colour. The kinematics and
scale-height of the sample shows that the sources with periods less than 1000
days must have low mass main-sequence progenitors. It is argued that the three
oxygen-rich stars with periods over 1000 days probably had intermediate mass
main-sequence progenitors with remaining stars having an average progenitor
mass of about 1.3 solar masses. The average lifetime of stars in this phase is
estimated to be about 4.0E4 years, indicating they will undergo at most one
more thermal pulse before leaving the AGB.Comment: 27 pages, 20 figures, accepted for MNRA
Niche-dependent genetic diversity in Antarctic metaviromes
The metaviromes from 2 different
Antarctic terrestrial soil niches have
been analyzed. Both hypoliths (microbial
assemblages beneath transluscent rocks)
and surrounding open soils showed a
high level diversity of tailed phages,
viruses of algae and amoeba, and virophage
sequences. Comparisons of other
global metaviromes with the Antarctic
libraries showed a niche-dependent clustering
pattern, unrelated to the geographical
origin of a given metavirome. Within
the Antarctic open soil metavirome, a
putative circularly permuted, »42kb
dsDNA virus genome was annotated,
showing features of a temperate phage
possessing a variety of conserved protein
domains with no significant taxonomic
affiliations in current databases.National Research Foundation (South Africa) and the Genomics Research Institute of the
University of Pretoria (South Africa).http://www.tandfonline.com/loi/kbac202015-12-31hb201
Simulations of idealised 3D atmospheric flows on terrestrial planets using LFRic-Atmosphere
We demonstrate that LFRic-Atmosphere, a model built using the Met Office's
GungHo dynamical core, is able to reproduce idealised large-scale atmospheric
circulation patterns specified by several widely-used benchmark recipes. This
is motivated by the rapid rate of exoplanet discovery and the ever-growing need
for numerical modelling and characterisation of their atmospheres. Here we
present LFRic-Atmosphere's results for the idealised tests imitating
circulation regimes commonly used in the exoplanet modelling community. The
benchmarks include three analytic forcing cases: the standard Held-Suarez test,
the Menou-Rauscher Earth-like test, and the Merlis-Schneider Tidally Locked
Earth test. Qualitatively, LFRic-Atmosphere agrees well with other numerical
models and shows excellent conservation properties in terms of total mass,
angular momentum and kinetic energy. We then use LFRic-Atmosphere with a more
realistic representation of physical processes (radiation, subgrid-scale
mixing, convection, clouds) by configuring it for the four TRAPPIST-1 Habitable
Atmosphere Intercomparison (THAI) scenarios. This is the first application of
LFRic-Atmosphere to a possible climate of a confirmed terrestrial exoplanet.
LFRic-Atmosphere reproduces the THAI scenarios within the spread of the
existing models across a range of key climatic variables. Our work shows that
LFRic-Atmosphere performs well in the seven benchmark tests for terrestrial
atmospheres, justifying its use in future exoplanet climate studies.Comment: 34 pages, 9(12) figures; Submitted to Geoscientific Model
Development; Comments are welcome (see Discussion tab on the journal's
website: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-647
Treatment outcome definitions in nontuberculous mycobacterial pulmonary disease: an NTM-NET consensus statement
Nontuberculous mycobacterial pulmonary diseases (NTM-PD) are increasingly recognised as opportunistic infections of humans. These chronic pulmonary infections have two main presentations. The first is a fibro-cavitary disease, that occurs in patients with pre-existing pulmonary diseases, such as chronic obstructive pulmonary disease, bronchiectasis, previous tuberculosis or other structural lung disease. The second presentation is a nodular- bronchiectatic disease of primarily the lingula and middle lobe that tends to affect a middle- aged and elderly female population [1]. Treatment of NTM-PD requires long-term administration of complex multidrug therapies that are species-specific. Currently recommended regimens are supported by a very limited evidence base [2, 3]. The increasing incidence of NTM-PD has sparked increased interest in performing prospective randomised clinical trials [4]. One of the drawbacks of the existing case series and clinical trials is that they have applied different outcome measures [5]. This hampers meta-analyses, which are important in these still understudied infectious diseases. To enhance the quality and interpretability of the results of future trials and retrospective cohort studies, we aimed to formulate clear and broadly acceptable outcome definitions for NTM-PD treatment
The metamorphosis of SN1998bw
We present and discuss the photometric and spectroscopic evolution of the
peculiar SN1998bw, associated with GRB980425, through an analysis of optical
and near IR data collected at ESO-La Silla. The spectroscopic data, spanning
the period from day -9 to day +376 (relative to B maximum), have shown that
this SN was unprecedented, although somewhat similar to SN1997ef. Maximum
expansion velocities as high as 3x10^4 km/s to some extent mask its resemblance
to other Type Ic SNe. At intermediate phases, between photospheric and fully
nebular, the expansion velocities (~10^4 km/s) remained exceptionally high
compared to those of other recorded core-collapse SNe at a similar phase. The
mild linear polarization detected at early epochs suggests the presence of
asymmetry in the emitting material. The degree of asymmetry, however, cannot be
decoded from these measurements alone. The HeI 1.083 mu and 2.058 mu lines are
identified and He is suggested to lie in an outer region of the envelope. The
temporal behavior of the fluxes and profiles of emission lines of MgI]4571A,
[OI]6300,6364A and a feature ascribed to Fe are traced to stimulate future
modeling work.Comment: 32 pages, 19 figures; ps file including figures at
http://www.eso.org/~fpatat/sn98b
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