329 research outputs found
Electrochemical reaction in single layer MoS2: nanopores opened atom by atom
Ultrathin nanopore membranes based on 2D materials have demonstrated ultimate
resolution toward DNA sequencing. Among them, molybdenum disulphide (MoS2)
shows long-term stability as well as superior sensitivity enabling high
throughput performance. The traditional method of fabricating nanopores with
nanometer precision is based on the use of focused electron beams in
transmission electron microscope (TEM). This nanopore fabrication process is
time-consuming, expensive, not scalable and hard to control below 1 nm. Here,
we exploited the electrochemical activity of MoS2 and developed a convenient
and scalable method to controllably make nanopores in single-layer MoS2 with
sub-nanometer precision using electrochemical reaction (ECR). The
electrochemical reaction on the surface of single-layer MoS2 is initiated at
the location of defects or single atom vacancy, followed by the successive
removals of individual atoms or unit cells from single-layer MoS2 lattice and
finally formation of a nanopore. Step-like features in the ionic current
through the growing nanopore provide direct feedback on the nanopore size
inferred from a widely used conductance vs. pore size model. Furthermore, DNA
translocations can be detected in-situ when as-fabricated MoS2 nanopores are
used. The atomic resolution and accessibility of this approach paves the way
for mass production of nanopores in 2D membranes for potential solid-state
nanopore sequencing.Comment: 13 pages, 4 figure
Secondary zoonotic dog-to-human transmission of SARS-CoV-2 suggested by timeline but refuted by viral genome sequencing
Purpose: The risk of secondary zoonotic transmission of SARS-CoV-2 from pet animals remains unclear. Here, we report on a 44 year old Caucasian male presenting to our clinic with COVID-19 pneumonia, who reported that his dog displayed respiratory signs shortly prior to his infection. The dog tested real-time-PCR (RT-PCR) positive for SARS-CoV-2 RNA and the timeline of events suggested a transmission from the dog to the patient.
Methods: RT-PCR and serological assays were used to confirm SARS-CoV-2 infection in the nasopharyngeal tract in the dog and the patient. We performed SARS-CoV-2-targeted amplicon-based next generation sequencing of respiratory samples from the dog and patient for sequence comparisons.
Results: SARS-CoV-2 infection of the dog was confirmed by three independent PCR-positive pharyngeal swabs and subsequent seroconversion. Sequence analysis identified two separate SARS-CoV-2 lineages in the canine and the patient’s respiratory samples. The timeline strongly suggested dog-to-human transmission, yet due to the genetic distance of the canine and the patient’s samples paired-transmission was highly unlikely.
Conclusion: The results of this case support current knowledge about the low risk of secondary zoonotic dog-to-human transmissions of SARS-CoV-2 and emphasizes the strength of genomic sequencing in deciphering viral transmission chains
Pressure Induced Quantum Critical Point and Non-Fermi-Liquid Behavior in BaVS3
The phase diagram of BaVS3 is studied under pressure using resistivity
measurements. The temperature of the metal to nonmagnetic Mott insulator
transition decreases under pressure, and vanishes at the quantum critical point
p_cr=20kbar. We find two kinds of anomalous conducting states. The
high-pressure metallic phase is a non-Fermi liquid described by Delta rho = T^n
where n=1.2-1.3 at 1K < T < 60K. At p<p_cr, the transition is preceded by a
wide precursor region with critically increasing resistivity which we ascribe
to the opening of a soft Coulomb gap.Comment: 4 pages, 5 eps figures, problem with figure correcte
Training of Instrumentalists and Development of New Technologies on SOFIA
This white paper is submitted to the Astronomy and Astrophysics 2010 Decadal
Survey (Astro2010)1 Committee on the State of the Profession to emphasize the
potential of the Stratospheric Observatory for Infrared Astronomy (SOFIA) to
contribute to the training of instrumentalists and observers, and to related
technology developments. This potential goes beyond the primary mission of
SOFIA, which is to carry out unique, high priority astronomical research.
SOFIA is a Boeing 747SP aircraft with a 2.5 meter telescope. It will enable
astronomical observations anywhere, any time, and at most wavelengths between
0.3 microns and 1.6 mm not accessible from ground-based observatories. These
attributes, accruing from the mobility and flight altitude of SOFIA, guarantee
a wealth of scientific return. Its instrument teams (nine in the first
generation) and guest investigators will do suborbital astronomy in a
shirt-sleeve environment. The project will invest $10M per year in science
instrument development over a lifetime of 20 years. This, frequent flight
opportunities, and operation that enables rapid changes of science instruments
and hands-on in-flight access to the instruments, assure a unique and extensive
potential - both for training young instrumentalists and for encouraging and
deploying nascent technologies. Novel instruments covering optical, infrared,
and submillimeter bands can be developed for and tested on SOFIA by their
developers (including apprentices) for their own observations and for those of
guest observers, to validate technologies and maximize observational
effectiveness.Comment: 10 pages, no figures, White Paper for Astro 2010 Survey Committee on
State of the Professio
Influence of airway management strategy on "no-flow-time" during an "Advanced life support course" for intensive care nurses – A single rescuer resuscitation manikin study
<p>Abstract</p> <p>Background</p> <p>In 1999, the laryngeal tube (VBM Medizintechnik, Sulz, Germany) was introduced as a new supraglottic airway. It was designed to allow either spontaneous breathing or controlled ventilation during anaesthesia; additionally it may serve as an alternative to endotracheal intubation, or bag-mask ventilation during resuscitation. Several variations of this supraglottic airway exist. In our study, we compared ventilation with the laryngeal tube suction for single use (LTS-D) and a bag-mask device. One of the main points of the revised ERC 2005 guidelines is a low no-flow-time (NFT). The NFT is defined as the time during which no chest compression occurs. Traditionally during the first few minutes of resuscitation NFT is very high. We evaluated the hypothesis that utilization of the LTS-D could reduce the NFT compared to bag-mask ventilation (BMV) during simulated cardiac arrest in a single rescuer manikin study.</p> <p>Methods</p> <p>Participants were studied during a one day advanced life support (ALS) course. Two scenarios of arrhythmias requiring defibrillation were simulated in a manikin. One scenario required subjects to establish the airway with a LTS-D; alternatively, the second scenario required them to use BMV. The scenario duration was 430 seconds for the LTS-D scenario, and 420 seconds for the BMV scenario, respectively. Experienced ICU nurses were recruited as study subjects. Participants were randomly assigned to one of the two groups first (LTS-D and BMV) to establish the airway. Endpoints were the total NFT during the scenario, the successful airway management using the respective device, and participants' preference of one of the two strategies for airway management.</p> <p>Results</p> <p>Utilization of the LTS-D reduced NFT significantly (p < 0.01). Adherence to the time frame of ERC guidelines was 96% in the LTS-D group versus 30% in the BMV group. Two participants in the LTS-D group required more than one attempt to establish the LTS-D correctly. Once established, ventilation was effective in 100%. In a subjective evaluation all participants preferred the LTS-D over BMV to provide ventilation in a cardiac arrest scenario.</p> <p>Conclusion</p> <p>In our manikin study, NFT was reduced significantly when using LTS-D compared to BMV. During cardiac arrest, the LTS-D might be a good alternative to BMV for providing and maintaining a patent airway. For personnel not experienced in endotracheal intubation it seems to be a safe airway device in a manikin use.</p
Partial “targeted” embolisation of brain arteriovenous malformations
The treatment of pial arteriovenous brain malformations is controversial. Little is yet known about their natural history, their pathomechanisms and the efficacy and risks of respective proposed treatments. It is known that only complete occlusion of the AVM can exclude future risk of haemorrhage and that the rates of curative embolisation of AVMs with an acceptable periprocedural risk are around 20 to 50%. As outlined in the present article, however, partial, targeted embolisation also plays a role. In acutely ruptured AVMs where the source of bleeding can be identified, targeted embolisation of this compartment may be able to secure the AVM prior to definitive treatment. In unruptured symptomatic AVMs targeted treatment may be employed if a defined pathomechanism can be identified that is related to the clinical symptoms and that can be cured with an acceptable risk via an endovascular approach depending on the individual AVM angioarchitecture. This review article gives examples of pathomechanisms and angioarchitectures that are amenable to this kind of treatment strategy
Search for Top Squark Pair Production in the Dielectron Channel
This report describes the first search for top squark pair production in the
channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using
74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence
level upper limit on sigma*B is presented. The limit is above the theoretical
expectation for sigma*B for this process, but does show the sensitivity of the
current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report
Measurement of the Top Quark Pair Production Cross Section in the All-jets Decay Channel
We present a measurement of tbar-t production using multijet final states in
pbar-p collisions at a center-of-mass energy of 1.8 TeV, with an integrated
luminosity of 110.3 pb(-1). The analysis has been optimized using neural
networks to achieve the smallest expected fractional uncertainty on the tbar-t
production cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/-
1.5(syst.) pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining this
result with previous D0 measurements, where one or both of the W bosons decay
leptonically, gives a tbar-t production cross section of 5.9 +/- 1.2(stat) +/-
1.1(syst) pb.Comment: 6 pages, 3 figures; no substative change in revisio
Measurement of the Top Quark Pair Production Cross Section in pbar-p Collisions Using Multijet Final States
We have studied tbar-t production using multijet final states in pbar-p
collisions at a center-of-mass energy of 1.8 TeV, with an integrated luminosity
of 110.3 pb(-1). Each of the top quarks with these final states decays
exclusively to a bottom quark and a W boson, with the W bosons decaying into
quark-antiquark pairs. The analysis has been optimized using neural networks to
achieve the smallest expected fractional uncertainty on the tbar-t production
cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/- 1.5(syst.)
pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining this result with
previous D0 measurements, where one or both of the W bosons decay leptonically,
gives a tbar t production cross section of 5.9 +/- 1.2(stat) +/- 1.1(syst) pb.Comment: 30 pages, 32 figures; no substative change in revisio
Second Generation Leptoquark Search in p\bar{p} Collisions at = 1.8 TeV
We report on a search for second generation leptoquarks with the D\O\
detector at the Fermilab Tevatron collider at = 1.8 TeV.
This search is based on 12.7 pb of data. Second generation leptoquarks
are assumed to be produced in pairs and to decay into a muon and quark with
branching ratio or to neutrino and quark with branching ratio
. We obtain cross section times branching ratio limits as a function
of leptoquark mass and set a lower limit on the leptoquark mass of 111
GeV/c for and 89 GeV/c for at the 95%\
confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-
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