10,865 research outputs found
Josephson oscillation linewidth of ion-irradiated YBaCuO junctions
We report on the noise properties of ion-irradiated YBaCuO
Josephson junctions. This work aims at investigating the linewidth of the
Josephson oscillation with a detector response experiment at 132 GHz.
Experimental results are compared with a simple analytical model based on the
Likharev-Semenov equation and the de Gennes dirty limit approximation. We show
that the main source of low-frequency fluctuations in these junctions is the
broadband Johnson noise and that the excess () noise contribution
does not prevail in the temperature range of interest, as reported in some
other types of high-T superconducting Josephson junctions. Finally, we
discuss the interest of ion-irradiated junctions to implement frequency-tunable
oscillators consisting of synchronized arrays of Josephson junctions
Out of sight, not out of mind: developments in economic models of groundwater management
Dynamic models of natural resource management have been applied to groundwater for decades, incorporating at least two inescapable aspects: first, since groundwater stocks are carried over to future periods, dynamic analysis is essential and any costs and benefits included in the analysis will require discounting; second, the positive and normative aspects of management must be clarified at the outset. The difference is fundamental even if the results of the two model types sometimes turn out to be fairly close. A whole strand of literature has been preoccupied with the question of whether policy interventions at least have the potential of improving groundwater management in a meaningful sense. However, given the well-documented parlous state of many aquifers around the world today, the focus has mostly shifted from debating whether or not intervention is worthwhile to identifying the relevant features of complex groundwater systems, designing better policies and facilitating their successful implementation. We survey developments in economic models relevant to groundwater management, focusing especially on the depiction of uncertainty and on the different methods applied to estimate the total economic value of groundwater.info:eu-repo/semantics/acceptedVersio
Urban Cholera transmission hotspots and their implications for Reactive Vaccination: evidence from Bissau city, Guinea Bissau
Use of cholera vaccines in response to epidemics (reactive vaccination) may provide an effective supplement to traditional control measures. In Haiti, reactive vaccination was considered but, until recently, rejected in part due to limited global supply of vaccine. Using Bissau City, Guinea-Bissau as a case study, we explore neighborhood-level transmission dynamics to understand if, with limited vaccine and likely delays, reactive vaccination can significantly change the course of a cholera epidemic
Susceptibility of SARS-CoV2 infection in children
Coronavirus disease 2019 in children presents with distinct phenotype in comparison to adults. Overall, the pediatric infection with a generally milder clinical course of the acute infection compared to adults still faces several unknown aspects. Specifically, the presence of a wide range of inflammatory manifestations, including multisystem inflammatory syndrome in children (MIS-C), myocarditis, and long COVID in the period after infection suggests a particular susceptibility of some children upon severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Albeit peculiar complications such as long covid are less frequent in children compared to adults, research on the relationship between inflammatory syndromes and SARS-CoV-2 is rapidly evolving. Conclusions: new studies and findings continue to emerge, providing further insights into the underlying mechanisms and potential therapeutic strategies. In the present work, we revised current knowledge of the main factors accounting for such variability upon SARS-CoV-2 infection over the pediatric age group.What is Known:& BULL; COVID19 in children overall showed a milder course compared to adults during the acute phase of the infection.& BULL; Children showed to be susceptible to a wide range of post infectious complications including multisystem inflammatory syndrome in children (MIS-C), myocarditis, neuroinflammation, and long COVID.What is New:& BULL; Mechanisms underlying susceptibility to a severe course of the infection were recently shown to pertain to the host.& BULL; A specific combination of HLA was recently shown to be associated to higher susceptibility to MIS-C in children
Mononeuritis multiplex: an uncommon neurological manifestation of cytomegalovirus reactivation in an HIV-infected patient
BACKGROUND: Cytomegalovirus (CMV) reactivation with neurological involvement in patients with acquired immunodeficiency syndrome (AIDS) is increasingly rare since the introduction of antiretroviral therapy (ART). Manifestations include encephalitis, myelitis, polyradiculopathy and, less commonly, mononeuritis multiplex (MNM). We report a case of disseminated CMV disease with gastrointestinal and peripheral and central nervous system involvement in a patient with AIDS, manifesting primarily as MNM. CASE PRESENTATION: A 31-year old woman with AIDS presented with a clinical picture of MNM. Electromyography confirmed the clinical findings. CMV DNA was detected in cerebrospinal fluid (CSF) and blood. Gastrointestinal involvement was histologically documented. HIV RNA was also detected in CSF and brain MRI was consistent with HIV encephalopathy. A diagnosis of disseminated CMV disease (with esophagitis, colitis, encephalitis and MNM) and HIV encephalopathy was made. Treatment consisted of ganciclovir and foscarnet, followed by maintenance therapy with valganciclovir. Evolution was favorable and valganciclovir was stopped after sustained immune recovery following ART initiation. CONCLUSION: We discuss the diagnostic approach to CMV neurological disease, with a focus on MNM and CMV encephalitis. Combination therapy with ganciclovir and foscarnet should be considered for all forms of neurological involvement, although available data are scarce. Since there is significant overlap between CMV encephalitis and HIV encephalopathy, ART drugs with higher CSF penetration may have to be considered. ART and immune recovery are essential to improve outcomes
Decoherence Rate of Semiconductor Charge Qubit Coupled to Acoustic Phonon Reservoir
We analyze decoherence of an electron in a double-dot due to the interaction
with acoustic phonons. For large tunneling rates between the quantum dots, the
main contribution to decoherence comes from the phonon emission relaxation
processes, while for small tunneling rates, the virtual-phonon, dephasing
processes dominate. Our results show that in common semiconductors, such as Si
and GaAs, the latter mechanism determines the upper limit for the double-dot
charge qubit performance measure.Comment: 4 pages, 2 figures, typos corrected, fig. 2 replaced by the improved
versio
Liposomal amphotericin B for visceral leishmaniasis in human immunodeficiency virus-coinfected patients: 2-year treatment outcomes in Bihar, India
Reports on treatment outcomes of visceral leishmaniasis (VL)-human immunodeficiency virus (HIV) coinfection in India are lacking. To our knowledge, none have studied the efficacy of liposomal amphotericin B in VL-HIV coinfection. We report the 2-year treatment outcomes of VL-HIV-coinfected patients treated with liposomal amphotericin B followed by combination antiretroviral treatment (cART) in Bihar, India
Targeting qubit states using open-loop control
We present an open-loop (bang-bang) scheme which drives an open two-level
quantum system to any target state, while maintaining quantum coherence
throughout the process. The control is illustrated by a realistic simulation
for both adiabatic and thermal decoherence. In the thermal decoherence regime,
the control achieved by the proposed scheme is qualitatively similar, at the
ensemble level, to the control realized by the quantum feedback scheme of Wang,
Wiseman, and Milburn [Phys. Rev. A 64, #063810 (2001)] for the spontaneous
emission of a two-level atom. The performance of the open-loop scheme compares
favorably against the quantum feedback scheme with respect to robustness,
target fidelity and transition times.Comment: 27 pages, 7 figure
Single-cell gene network analysis and transcriptional landscape of MYCN-amplified neuroblastoma cell lines
Neuroblastoma (NBL) is a pediatric cancer responsible for more than 15% of cancer deaths in children, with 800 new cases each year in the United States alone. Genomic amplification of the MYC oncogene family member MYCN characterizes a subset of high-risk pediatric neuroblastomas. Several cellular models have been implemented to study this disease over the years. Two of these, SK-N-BE-2-C (BE2C) and Kelly, are amongst the most used worldwide as models of MYCN-Amplified human NBL. Here, we provide a transcriptome-wide quantitative measurement of gene expression and transcriptional network activity in BE2C and Kelly cell lines at an unprecedented single-cell resolution. We obtained 1105 Kelly and 962 BE2C unsynchronized cells, with an average number of mapped reads/cell of roughly 38,000. The single-cell data recapitulate gene expression signatures previously generated from bulk RNA-Seq. We highlight low variance for commonly used housekeeping genes between different cells (ACTB, B2M and GAPDH), while showing higher than expected variance for metallothionein transcripts in Kelly cells. The high number of samples, despite the relatively low read coverage of single cells, allowed for robust pathway enrichment analysis and master regulator analysis (MRA), both of which highlight the more mesenchymal nature of BE2C cells as compared to Kelly cells, and the upregulation of TWIST1 and DNAJC1 transcriptional networks. We further defined master regulators at the single cell level and showed that MYCN is not constantly active or expressed within Kelly and BE2C cells, independently of cell cycle phase. The dataset, alongside a detailed and commented programming protocol to analyze it, is fully shared and reusable
Inflation with a stringy minimal length, reworked
In this paper we revisit the formulation of scalar field theories on de
Sitter backgrounds subject to the generalized uncertainty principle (GUP). The
GUP arises in several contexts in string theory, but is most readily thought of
as resulting from using strings as effective probes of geometry, which suggests
an uncertainty relation incorporating the string scale . After reviewing
the string theoretic case for the GUP, which implies a minimum length scale
, we follow in the footsteps of Kempf and concern ourselves with how one
might write down field theories which respect the GUP. We uncover a new
representation of the GUP, which unlike previous studies, readily permits exact
analytical solutions for the mode functions of a scalar field on de Sitter
backgrounds. We find that scalar fields cannot be quantized on inflationary
backgrounds with a Hubble radius smaller than the string scale,
implying a sensibly stringy (as opposed to Planckian) cutoff on the scale of
inflation resulting from the GUP. We also compute corrections to
the two point correlation function analytically and comment on the future
prospects of observing such corrections in the fortunate circumstance our
universe is described by a very weakly coupled string theory.Comment: To appear in JHEP. Sub-section discussing how our approach avoids
certain ordering ambiguities adde
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