4,805 research outputs found
Enhanced Shot Noise in Tunneling through a Stack of Coupled Quantum Dots
We have investigated the noise properties of the tunneling current through
vertically coupled self-assembled InAs quantum dots. We observe
super-Poissonian shot noise at low temperatures. For increased temperature this
effect is suppressed. The super-Poissonian noise is explained by capacitive
coupling between different stacks of quantum dots
Festuca paniculata meadows in Ticino (Switzerland) and their Alpine environment
Festuca paniculata (L.) Schinz & Thellung locally dominates montane and subalpine meadows of the Alps and other mountains of southern Europe. Vegetation releves were carried out in Switzerland and northern Italy to study the site conditions under which Festuca paniculata meadows occur in this part of the Alps, their species composition and phytosociological status, and their relationship to Festuca paniculata meadows described previously from the French Alps (Centaureo-Festucetum spadiceae) and Austrian Alps (Hypochaerido uniflorae-Festucetum paniculatae). The Swiss meadows were found to have a similar ecology to those in France and Austria. They occur mostly between 1600 and 2100 m a.s.l on steep slopes with southern aspect, generally on crystalline rocks, but sometimes on calcareous rocks if soils have been decalcified. The species composition of the Swiss meadows is closer to the Austrian than to the French communities, and we attribute them to the association Hypochaerido uniflorae-Festucetum paniculatae with the new subassociation polygaletosum chamaebuxi. Climate is probably the main factor separating vegetation units in the Alps: the Centaureo-Festucetum spadiceae occurs where summers are dry, whereas the Hypochaerido uniflorae-Festucetum paniculatae occurs where rainfall is not a limiting factor in summer
Morsures, piqûres et empoisonnements dans l’Histoire Naturelle de Pline l’Ancien
This article aims to explain the large amount of space devoted by Pliny in his Natural History to remedies for the effects of bites and poisonous substances. Pliny is a compiler and reports a medical tradition known from the Alexandrian age. The interest of Pliny and other authors in this matter reflects a fear arising especially from two causes : on the one hand, the discovery by Greeks and Romans of Asian and African venomous animals ; on the other hand, the poisons used since Hellenistic times for criminal purposes. There are, however, other factors directly linked to Pliny’s life and beliefs : the use – and abuse – of poison in Nero’s time, the theme of the serpent in contemporary literature, and, above all, Pliny’s adherence to the doctrine of ‘sympathies’ and ‘antipathies’. In holding this point of view, Pliny has been influenced profoundly by a Pseudo-Democritus, Bolos of Mendes, the author of a lost book On Sympathies and Antipathies, with extensive discussion of magic, an art associating knowledge of animals, poisons and their remedies
Long thoracic nerve release for scapular winging: Clinical study of a continuous series of eight patients
SummaryScapular winging secondary to serratus anterior muscle palsy is a rare pathology. It is usually due to a lesion in the thoracic part of the long thoracic nerve following violent upper-limb stretching with compression on the nerve by the anterior branch of thoracodorsal artery at the “crow's foot landmark” where the artery crosses in front of the nerve. Scapular winging causes upper-limb pain, fatigability or impotence. Diagnosis is clinical and management initially conservative. When functional treatment by physiotherapy fails to bring recovery within 6months and electromyography (EMG) shows increased distal latencies, neurolysis may be suggested. Muscle transfer and scapula-thoracic arthrodesis are considered as palliative treatments. We report a single-surgeon experience of nine open neurolyses of the thoracic part of the long thoracic nerve in eight patients. At 6months’ follow-up, no patients showed continuing signs of winged scapula. Control EMG showed significant reduction in distal latency; Constant scores showed improvement, and VAS-assessed pain was considerably reduced. Neurolysis would thus seem to be the first-line surgical attitude of choice in case of compression confirmed on EMG. The present results would need to be confirmed in larger studies with longer follow-up, but this is made difficult by the rarity of this pathology.Level of evidenceIII
The end of life experiences of people living with socio-economic deprivation in the developed world:an integrative review
The roles of Emma Carduff and Maire O'Riordan are funded by Marie Curie. Emma Carduff is Co-Applicant on an Economic and Social Research Council grant (ES/S014373/1) entitled Dying in the Margins: uncovering the reasons for unequal access to home dying for the socio-economically deprived.Background: Those experiencing socioeconomic deprivation have poorer quality of health throughout their life course which can result in poorer quality of death - with decreased access to palliative care services, greater use of acute care, and reduced access to preferred place of care compared with patients from less deprived populations. Aim: To summarise the current global evidence from developed countries on end-of-life experience for those living with socio-economic deprivation. Design: Integrative review in accordance with PRISMA. A thorough search of major databases from 2010-2020, using clear definitions of end-of-life care and well-established proxy indicators of socio-economic deprivation. Empirical research describing experience of adult patients in the last year of life care were included. Results: Forty studies were included from a total of 3508 after screening and selection. These were deemed to be of high quality; from a wide range of countries with varying healthcare systems; and encompassed all palliative care settings for patients with malignant and non-malignant diagnoses. Three global themes were identified: 1) multi-dimensional symptom burden, 2) preferences and planning and 3) health and social care interactions at the end of life. Conclusions: Current models of healthcare services are not meeting the needs of those experiencing socioeconomic deprivation at the end-of-life. Further work is needed to understand the disparity in care, particularly around ensuring patients voices are heard and can influence service development and delivery.Publisher PDFPeer reviewe
Search for cool giant exoplanets around young and nearby stars - VLT/NaCo near-infrared phase-coronagraphic and differential imaging
[Abridged] Context. Spectral differential imaging (SDI) is part of the
observing strategy of current and future high-contrast imaging instruments. It
aims to reduce the stellar speckles that prevent the detection of cool planets
by using in/out methane-band images. It attenuates the signature of off-axis
companions to the star, such as angular differential imaging (ADI). However,
this attenuation depends on the spectral properties of the low-mass companions
we are searching for. The implications of this particularity on estimating the
detection limits have been poorly explored so far. Aims. We perform an imaging
survey to search for cool (Teff<1000-1300 K) giant planets at separations as
close as 5-10 AU. We also aim to assess the sensitivity limits in SDI data
taking the photometric bias into account. This will lead to a better view of
the SDI performance. Methods. We observed a selected sample of 16 stars (age <
200 Myr, d < 25 pc) with the phase-mask coronagraph, SDI, and ADI modes of
VLT/NaCo. Results. We do not detect any companions. As for the sensitivity
limits, we argue that the SDI residual noise cannot be converted into mass
limits because it represents a differential flux, unlike the case of
single-band images. This results in degeneracies for the mass limits, which may
be removed with the use of single-band constraints. We instead employ a method
of directly determining the mass limits. The survey is sensitive to cool giant
planets beyond 10 AU for 65% and 30 AU for 100% of the sample. Conclusions. For
close-in separations, the optimal regime for SDI corresponds to SDI flux ratios
>2. According to the BT-Settl model, this translates into Teff<800 K. The
methods described here can be applied to the data interpretation of SPHERE. We
expect better performance with the dual-band imager IRDIS, thanks to more
suitable filter characteristics and better image quality.Comment: 19 pages, 16 figures, accepted for publication in A&A, version
including language editin
Search for cool extrasolar giant planets combining coronagraphy, spectral and angular differential imaging
Spectral differential imaging (SDI) is part of the observing strategy of
current and on-going high-contrast imaging instruments on ground-based
telescopes. Although it improves the star light rejection, SDI attenuates the
signature of off-axis companions to the star, just like angular differential
imaging (ADI). However, the attenuation due to SDI has the peculiarity of being
dependent on the spectral properties of the companions. To date, no study has
investigated these effects. Our team is addressing this problem based on data
from a direct imaging survey of 16 stars combining the phase-mask coronagraph,
the SDI and the ADI modes of VLT/NaCo. The objective of the survey is to search
for cool (Teff<1000-1300 K) giant planets at separations of 5-10 AU orbiting
young, nearby stars (<200 Myr, <25 pc). The data analysis did not yield any
detections. As for the estimation of the sensitivity limits of SDI-processed
images, we show that it requires a different analysis than that used in
ADI-based surveys. Based on a method using the flux predictions of evolutionary
models and avoiding the estimation of contrast, we determine directly the mass
sensitivity limits of the survey for the ADI processing alone and with the
combination of SDI and ADI. We show that SDI does not systematically improve
the sensitivity due to the spectral properties and self-subtraction of point
sources.Comment: 5 pages, 2 figure
Measurement of the electron drift velocity for directional dark matter detectors
Three-dimensional track reconstruction is a key issue for directional Dark
Matter detection. It requires a precise knowledge of the electron drift
velocity. Magboltz simulations are known to give a good evaluation of this
parameter. However, large TPC operated underground on long time scale may be
characterized by an effective electron drift velocity that may differ from the
value evaluated by simulation. In situ measurement of this key parameter is
hence a way to avoid bias in the 3D track reconstruction. We present a
dedicated method for the measurement of the electron drift velocity with the
MIMAC detector. It is tested on two gas mixtures : and . We also show that adding allows us to lower the
electron drift velocity while keeping almost the same Fluorine content of the
gas mixture.Comment: Proceedings of the 4th international conference on Directional
Detection of Dark Matter (CYGNUS 2013), 10-12 June 2013, Toyama, Japa
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