Microwave-induced control of Free Electron Laser radiation

The dynamical response of a relativistic bunch of electrons injected in a planar magnetic undulator and interacting with a counterpropagating electromagnetic wave is studied. We demonstrate a resonance condition for which the free electron laser (FEL) dynamics is strongly influenced by the presence of the external field. It opens up the possibility of control of short wavelength FEL emission characteristics by changing the parameters of the microwave field without requiring change in the undulator's geometry or configuration. Numerical examples, assuming realistic parameter values analogous to those of the TTF-FEL, currently under development at DESY, are given for possible control of the amplitude or the polarization of the emitted radiation.Comment: 14 pages, 5 figures, accepted for publication in Phys. Rev.

Temporal changes in secondary prevention and cardiovascular outcomes after revascularization for peripheral arterial disease in Denmark: a nationwide cohort study

Background:Patients with peripheral arterial disease (PAD) are at increased risk of cardiovascular morbidity and mortality. Medical prevention with antithrombotic and statin therapies is a mainstay of treatment to prevent adverse outcomes; nevertheless, patients with PAD are often undertreated. This study describes the temporal changes in medical prevention and adverse outcomes in a national cohort of patients with symptomatic PAD after revascularization.Methods:We identified all patients with a first open surgical or endovascular revascularization procedure in the lower extremities or abdomen in Denmark, from 2000 to 2016. We examined temporal changes in the use of aspirin, clopidogrel, and statins and 1-year cause-specific hazard ratios for adverse clinical outcomes, after adjusting for procedure type, treatment indication, age, sex, and cardiovascular risk factors. The analyses were performed overall and within strata of index procedure (endovascular versus surgical), treatment indication, age, sex, and high-risk comorbidities.Results:Between 2000 and 2016, we identified 32 911 patients who underwent revascularization for symptomatic PAD. The mean age was 69 years and increased over time, as did the burden of comorbidity. The cumulative incidence of medication use increased between 2000 to 2004 and 2013 to 2016, respectively, from 57.3% to 64.3% for aspirin, 3.6% to 24.8% for clopidogrel, and 36.2% to 77.1% for statins. Concurrently, the 1-year outcome rates declined. Compared with 2000 to 2004, the adjusted hazard ratios in 2013 to 2016 were 0.73 (95% CI, 0.62-0.84) for major adverse cardiovascular events, 0.92 (95% CI, 0.85-1.00) for major adverse limb events, 0.60 (95% CI, 0.48-0.74) for myocardial infarction, 0.94 (95% CI, 0.75-1.18) for ischemic stroke, 0.92 (95% CI, 0.75-1.12) for major bleeding, 0.54 (95% CI, 0.39-0.76) for cardiovascular death, and 0.80 (95% CI, 0.72-0.88) for all-cause death. These improvements in prognosis were most prominent from 2000 to 2004 to 2005 to 2008 and occurred in all strata of index procedure, treatment indication, sex, age, and comorbidity. In contrast, the adjusted hazard ratio for major amputations was 1.00 (95% CI, 0.90-1.11) when comparing 2013 to 2016 to 2000 to 2004.Conclusions:Medical prevention of adverse events has increased considerably over time in patients who underwent revascularization for symptomatic PAD. This increase was accompanied by reductions in all adverse outcomes, except major amputations.Diabetes mellitus: pathophysiological changes and therap

The Pediatric Cell Atlas: defining the growth phase of human development at single-cell resolution

Single-cell gene expression analyses of mammalian tissues have uncovered profound stage-specific molecular regulatory phenomena that have changed the understanding of unique cell types and signaling pathways critical for lineage determination, morphogenesis, and growth. We discuss here the case for a Pediatric Cell Atlas as part of the Human Cell Atlas consortium to provide single-cell profiles and spatial characterization of gene expression across human tissues and organs. Such data will complement adult and developmentally focused HCA projects to provide a rich cytogenomic framework for understanding not only pediatric health and disease but also environmental and genetic impacts across the human lifespan

Health Impairments in Children and Adolescents After Hospitalization for Acute COVID-19 or MIS-C

OBJECTIVES: To evaluate risk factors for postdischarge sequelae in children and adolescents hospitalized for acute coronavirus disease 2019 (COVID-19) or multisystem inflammatory syndrome in children (MIS-C). METHODS: Multicenter prospective cohort study conducted in 25 United States pediatric hospitals. Patients <21-years-old, hospitalized May 2020 to May 2021 for acute COVID-19 or MIS-C with follow-up 2 to 4 months after admission. We assessed readmissions, persistent symptoms or activity impairment, and new morbidities. Multivariable regression was used to calculate adjusted risk ratios (aRR) and 95% confidence intervals (CI). RESULTS: Of 358 eligible patients, 2 to 4 month survey data were available for 119 of 155 (76.8%) with acute COVID-19 and 160 of 203 (78.8%) with MIS-C. Thirteen (11%) patients with acute COVID-19 and 12 (8%) with MIS-C had a readmission. Thirty-two (26.9%) patients with acute COVID-19 had persistent symptoms (22.7%) or activity impairment (14.3%) and 48 (30.0%) with MIS-C had persistent symptoms (20.0%) or activity impairment (21.3%). For patients with acute COVID-19, persistent symptoms (aRR, 1.29 [95% CI, 1.04-1.59]) and activity impairment (aRR, 1.37 [95% CI, 1.06-1.78]) were associated with more organ systems involved. Patients with MIS-C and pre-existing respiratory conditions more frequently had persistent symptoms (aRR, 3.09 [95% CI, 1.55-6.14]) and those with obesity more frequently had activity impairment (aRR, 2.52 [95% CI, 1.35-4.69]). New morbidities were infrequent (9% COVID-19, 1% MIS-C). CONCLUSIONS: Over 1 in 4 children hospitalized with acute COVID-19 or MIS-C experienced persistent symptoms or activity impairment for at least 2 months. Patients with MIS-C and respiratory conditions or obesity are at higher risk of prolonged recovery

Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode

We report a measurement of the ttbar production cross section using the CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is consistent with the standard model prediction.Comment: By CDF collaboratio