The DARWIN observatory is a proposed next-generation experiment with 40 tonnes of liquid xenon as an active target in a time projection chamber. To study challenges related to the construction and ...operation of a multi-tonne scale detector, we have designed and constructed a vertical, full-scale demonstrator for the DARWIN experiment at the University of Zurich. Here, we present the first results from a several-months run with
343
kg
of xenon and electron drift lifetime and transport measurements with a
53
cm
tall purity monitor immersed in the cryogenic liquid. After
88
days
of continuous purification, the electron lifetime reached a value of
(
664
±
23
)
μ
s
. We measured the drift velocity of electrons for electric fields in the range (25–75) V/cm, and found values consistent with previous measurements. We also calculated the longitudinal diffusion constant of the electron cloud in the same field range, and compared with previous data, as well as with predictions from an empirical model.
For the first time, a small dual-phase (liquid/gas) xenon time projection chamber was equipped with a top array of silicon photomultipliers for light and charge readout. Here we describe the ...instrument in detail, as well as the data processing and the event position reconstruction algorithms. We obtain a spatial resolution of
∼
1.5
mm
in the horizontal plane. To characterise the detector performance, we show calibration data with internal
83
m
Kr
and
37
Ar
sources, and we detail the production of the latter as well as its introduction into the system. We finally compare the observed light and charge yields down to electronic recoil energies of
2.82
keV
to predictions based on NEST v2.0.
Abstract
The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of
$$^{136}$$
136
Xe. Out of its 50 t total ...natural xenon inventory, 40 t will be the active target of a time projection chamber which thus contains about 3.6 t of
$$^{136}$$
136
Xe. Here, we show that its projected half-life sensitivity is
$$2.4\times {10}^{27}\,{\hbox {year}}$$
2.4
×
10
27
year
, using a fiducial volume of 5 t of natural xenon and 10 year of operation with a background rate of less than 0.2 events/(t
$$\cdot $$
·
year) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in
$$^{136}$$
136
Xe.
We detail the sensitivity of the proposed liquid xenon DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five ...solar neutrino components:
pp
,
7
Be,
13
N,
15
O and
pep
. The precision of the
13
N,
15
O and
pep
components is hindered by the double-beta decay of
136
Xe and, thus, would benefit from a depleted target. A high-statistics observation of
pp
neutrinos would allow us to infer the values of the electroweak mixing angle,
sin
2
θ
w
, and the electron-type neutrino survival probability,
P
ee
, in the electron recoil energy region from a few keV up to 200 keV for the first time, with relative precision of 5% and 4%, respectively, with 10 live years of data and a 30 tonne fiducial volume. An observation of
pp
and
7
Be neutrinos would constrain the neutrino-inferred solar luminosity down to 0.2%. A combination of all flux measurements would distinguish between the high- (GS98) and low-metallicity (AGS09) solar models with 2.1–2.5
σ
significance, independent of external measurements from other experiments or a measurement of
8
B neutrinos through coherent elastic neutrino-nucleus scattering in DARWIN. Finally, we demonstrate that with a depleted target DARWIN may be sensitive to the neutrino capture process of
131
Xe.
Abstract
Background
Point-of-care ultrasound (POCUS) can aid geriatricians in caring for complex, older patients. Currently, there is limited literature on POCUS use by geriatricians. We conducted a ...national survey to assess current POCUS use, training desired, and barriers among Geriatrics and Extended Care (“geriatric”) clinics at Veterans Affairs Medical Centers (VAMCs).
Methods
We conducted a prospective observational study of all VAMCs between August 2019 and March 2020 using a web-based survey sent to all VAMC Chiefs of Staff and Chiefs of geriatric clinics.
Results
All Chiefs of Staff (
n
=130) completed the survey (100% response rate). Chiefs of geriatric clinics (“chiefs”) at 76 VAMCs were surveyed and 52 completed the survey (68% response rate). Geriatric clinics were located throughout the United States, mostly at high-complexity, urban VAMCs. Only 15% of chiefs responded that there was some POCUS usage in their geriatric clinic, but more than 60% of chiefs would support the implementation of POCUS use. The most common POCUS applications used in geriatric clinics were the evaluation of the bladder and urinary obstruction. Barriers to POCUS use included a lack of trained providers (56%), ultrasound equipment (50%), and funding for training (35%). Additionally, chiefs reported time utilization, clinical indications, and low patient census as barriers.
Conclusions
POCUS has several potential applications for clinicians caring for geriatric patients. Though only 15% of geriatric clinics at VAMCs currently use POCUS, most geriatric chiefs would support implementing POCUS use as a diagnostic tool. The greatest barriers to POCUS implementation in geriatric clinics were a lack of training and ultrasound equipment. Addressing these barriers systematically can facilitate implementation of POCUS use into practice and permit assessment of the impact of POCUS on geriatric care in the future.
Aims: To clone the gene encoding the enzyme with laccase activity expressed by Stenotrophomonas maltophilia AAP56 and to construct an insertional mutation in that gene to determine its effect on dye ...decolourization and laccase activity in this strain. Methods and Results: Comparative genomics of Sten. maltophilia strains K279a and R551‐3 revealed copA (coding for putative multicopper oxidase) as a candidate gene to encode an enzyme with laccase activity. Stenotrophomonas maltophilia AAP56 copA was amplified by degenerated PCR and cloned. A copA mutant strain, named Stemur, was constructed by homologous recombination. The comparison of wild‐type and mutant strains revealed that CopA shows laccase activity, and it is involved in copper resistance and in vitro dye decolorization. On the contrary, the mutation in copA did not affect the in vivo dye removal by Sten. maltophilia. Conclusions: Stenotrophomonas maltophilia AAP56 shows different mechanisms for dye decolorization. The gene encoding the laccase has been identified, and it has been shown that it is involved in the in vitro decolorization. Significance and Impact of the Study: Stenotrophomonas maltophilia is a micro‐organism of interest in different biotechnological processes including dye removal. This is the first report to address the molecular mechanism of this capacity, what will contribute to further improvements in the process.
Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With
40
t
of liquid xenon (LXe) in ...the TPC baseline design, DARWIN will have a high sensitivity for the detection of particle dark matter, neutrinoless double beta decay (
0
ν
β
β
), and axion-like particles (ALPs). Although cosmic muons are a source of background that cannot be entirely eliminated, they may be greatly diminished by placing the detector deep underground. In this study, we used Monte Carlo simulations to model the cosmogenic background expected for the DARWIN observatory at four underground laboratories: Laboratori Nazionali del Gran Sasso (LNGS), Sanford Underground Research Facility (SURF), Laboratoire Souterrain de Modane (LSM) and SNOLAB. We present here the results of simulations performed to determine the production rate of
137
Xe, the most crucial isotope in the search for
0
ν
β
β
of
136
Xe. Additionally, we explore the contribution that other muon-induced spallation products, such as other unstable xenon isotopes and tritium, may have on the cosmogenic background.
The precocity and efficacy of the vaccines developed so far against COVID-19 has been the most significant and saving advance against the pandemic. The development of vaccines has not prevented, ...during the whole period of the pandemic, the constant search for therapeutic medicines, both among existing drugs with different indications and in the development of new drugs. The Scientific Committee of the COVID-19 of the Illustrious College of Physicians of Madrid wanted to offer an early, simplified and critical approach to these new drugs, to new developments in immunotherapy and to what has been learned from the immune response modulators already known and which have proven effective against the virus, in order to help understand the current situation.
Insights for COVID-19 in 2023 Martín Sánchez, F J; Martínez-Sellés, M; Molero García, J M ...
Revista española de quimioterapia,
04/2023, Letnik:
36, Številka:
2
Journal Article
Odprti dostop
Predictions for a near end of the pandemic by the World Health Organization should be interpreted with caution. Current evidence indicates that the efficacy of a fourth dose of classical mRNA ...vaccines (BT162b2 or mRNA-1273) is low and short-lived in preventing SARS-CoV-2 infection in its predominant variant (Omicron). However, its efficacy is high against severe symptomatic infection, hospitalization and death. The new vaccines being introduced are bivalent and active against the Omicron variants. Potential new vaccines to be introduced in the coming year include a vaccine based on a recombinant protein that emulates the receptor binding domain of the Spike protein under development by the Spanish company Hipra, as well as vaccines for nasal or oral administration. Available information suggests that vaccines against COVID-19 can be administered in association with influenza vaccination without particular complications. New drugs against COVID-19, both antiviral and anti-inflammatory, are under investigation, but this does not seem to be the case with monoclonal antibodies. The indication to use masks in some circumstances will be maintained next year in view of the accumulation of scientific data on their efficacy. Finally, the long COVID or Post-COVID syndrome may continue to affect a very high proportion of patients who have had the disease, requiring combined diagnostic and therapeutic resources.
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