121 research outputs found
Discovering a Light Higgs Boson with Light
We evaluate the prospects for detecting a non-standard light Higgs boson with
a significant branching ratio to two photons, in Run II of the Fermilab
Tevatron. We derive the reach for several channels: inclusive,
jet and jets. We present the expected Run II limits on
the branching ratio of as a function of the Higgs mass, for
the case of ``bosonic'', as well as ``topcolor'' Higgs bosons.Comment: 11 pages, LaTeX, 7 figures, 4 tables, uses aipproc2.sty, contributed
to the Physics at Run II Workshop, analysis redone with optimized cuts and
improved background estimate, references adde
Searching for a light Fermiophobic Higgs Boson at the Tevatron
We propose new production mechanisms for light fermiophobic Higgs bosons
() with suppressed couplings to vector bosons () at the Fermilab
Tevatron. These mechanisms (e.g. ) are complementary to the
conventional process , which suffers from a strong suppression of
in realistic models with a . The new mechanisms extend the
coverage at the Tevatron Run II to the larger region, and offer the
possibility of observing new event topologies with up to 4 photons.Comment: 15 pages, including 5 eps-figure
The CP-conserving two-Higgs-doublet model: the approach to the decoupling limit
A CP-even neutral Higgs boson with Standard-Model-like couplings may be the
lightest scalar of a two-Higgs-doublet model. We study the decoupling limit of
the most general CP-conserving two-Higgs-doublet model, where the mass of the
lightest Higgs scalar is significantly smaller than the masses of the other
Higgs bosons of the model. In this case, the properties of the lightest Higgs
boson are nearly indistinguishable from those of the Standard Model Higgs
boson. The first non-trivial corrections to Higgs couplings in the approach to
the decoupling limit are also evaluated. The importance of detecting such
deviations in precision Higgs measurements at future colliders is emphasized.
We also clarify the case in which a neutral Higgs boson can possess
Standard-Model-like couplings in a regime where the decoupling limit does not
apply. The two-Higgs-doublet sector of the minimal supersymmetric model
illustrates many of the above features.Comment: 54 pages, 2 tables, revtex4 format, some new material added
(including elegant forms for the three-Higgs and four-Higgs couplings) and
typographical errors fixe
Impact of respirator versus surgical masks on SARS-CoV-2 acquisition in healthcare workers: a prospective multicentre cohort.
BACKGROUND
There is insufficient evidence regarding the role of respirators in the prevention of SARS-CoV-2 infection. We analysed the impact of filtering facepiece class 2 (FFP2) versus surgical masks on the risk of SARS-CoV-2 acquisition among Swiss healthcare workers (HCW).
METHODS
Our prospective multicentre cohort enrolled HCW from June to August 2020. Participants were asked about COVID-19 risk exposures/behaviours, including preferentially worn mask type when caring for COVID-19 patients outside of aerosol-generating procedures. The impact of FFP2 on (1) self-reported SARS-CoV-2-positive nasopharyngeal PCR/rapid antigen tests captured during weekly surveys, and (2) SARS-CoV-2 seroconversion between baseline and January/February 2021 was assessed.
RESULTS
We enrolled 3259 participants from nine healthcare institutions, whereof 716 (22%) preferentially used FFP2. Among these, 81/716 (11%) reported a SARS-CoV-2-positive swab, compared to 352/2543 (14%) surgical mask users; seroconversion was documented in 85/656 (13%) FFP2 and 426/2255 (19%) surgical mask users. Adjusted for baseline characteristics, COVID-19 exposure, and risk behaviour, FFP2 use was non-significantly associated with decreased risk for SARS-CoV-2-positive swab (adjusted hazard ratio [aHR] 0.8, 95% CI 0.6-1.0) and seroconversion (adjusted odds ratio [aOR] 0.7, 95% CI 0.5-1.0); household exposure was the strongest risk factor (aHR 10.1, 95% CI 7.5-13.5; aOR 5.0, 95% CI 3.9-6.5). In subgroup analysis, FFP2 use was clearly protective among those with frequent (> 20 patients) COVID-19 exposure (aHR 0.7 for positive swab, 95% CI 0.5-0.8; aOR 0.6 for seroconversion, 95% CI 0.4-1.0).
CONCLUSIONS
Respirators compared to surgical masks may convey additional protection from SARS-CoV-2 for HCW with frequent exposure to COVID-19 patients
NEOadjuvant therapy monitoring with PET and CT in Esophageal Cancer (NEOPEC-trial)
Contains fulltext :
70883.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Surgical resection is the preferred treatment of potentially curable esophageal cancer. To improve long term patient outcome, many institutes apply neoadjuvant chemoradiotherapy. In a large proportion of patients no response to chemoradiotherapy is achieved. These patients suffer from toxic and ineffective neoadjuvant treatment, while appropriate surgical therapy is delayed. For this reason a diagnostic test that allows for accurate prediction of tumor response early during chemoradiotherapy is of crucial importance. CT-scan and endoscopic ultrasound have limited accuracy in predicting histopathologic tumor response. Data suggest that metabolic changes in tumor tissue as measured by FDG-PET predict response better. This study aims to compare FDG-PET and CT-scan for the early prediction of non-response to preoperative chemoradiotherapy in patients with potentially curable esophageal cancer. METHODS/DESIGN: Prognostic accuracy study, embedded in a randomized multicenter Dutch trial comparing neoadjuvant chemoradiotherapy for 5 weeks followed by surgery versus surgery alone for esophageal cancer. This prognostic accuracy study is performed only in the neoadjuvant arm of the randomized trial. In 6 centers, 150 consecutive patients will be included over a 3 year period. FDG-PET and CT-scan will be performed before and 2 weeks after the start of the chemoradiotherapy. All patients complete the 5 weeks regimen of neoadjuvant chemoradiotherapy, regardless the test results. Pathological examination of the surgical resection specimen will be used as reference standard. Responders are defined as patients with < 10% viable residual tumor cells (Mandard-score).Difference in accuracy (area under ROC curve) and negative predictive value between FDG-PET and CT-scan are primary endpoints. Furthermore, an economic evaluation will be performed, comparing survival and costs associated with the use of FDG-PET (or CT-scan) to predict tumor response with survival and costs of neoadjuvant chemoradiotherapy without prediction of response (reference strategy). DISCUSSION: The NEOPEC-trial could be the first sufficiently powered study that helps justify implementation of FDG-PET for response-monitoring in patients with esophageal cancer in clinical practice. TRIAL REGISTRATION: ISRCTN45750457
Diagnostic and microsurgical presentation of intracranial angiolipomas. Case report and review of the literature.
Angiolipomas (ALs) are hamartomas composed of abnormally differentiated vessels and mature adipose tissue. Although they are most commonly found in peripheral tissues, ALs sometimes grow in the spinal epidural space. Intracranial ALs (ICALs) are rare: only seven cases have been reported in the literature. The authors describe the case of a 70-year-old woman who presented with ocular symptoms from a clinically and radiologically progressing parasellar ICAL. The radiological as well as the microsurgical findings are illustrated and compared with the seven previously published cases. The most frequent location of ALs is the skull base, especially the parasellar region. Other ICALs were diagnosed as components of cerebral arteriovenous malformations and were not symptomatic by themselves. Neuroradiological studies of ICALs usually demonstrate the characteristics of both adipose and vascular tissues. However, a review of the literature shows that the diagnosis had not been suspected preoperatively in any of the cases. Operative descriptions emphasize that most neurosurgeons were caught off guard by the profuse bleeding and the unusual relationship of this unexpected lesion to the cavernous sinus, so that removal was rarely complete. The authors conclude that preoperative diagnosis of ICALs is achievable based on magnetic resonance analysis, which should help optimize the microsurgical management of these lesions
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Theta stimulation polymerizes actin in dendritic spines of hippocampus
It has been proposed that the endurance of long-term potentiation (LTP) depends on structural changes entailing reorganization of the spine actin cytoskeleton. The present study used a new technique involving intracellular and extracellular application of rhodamine-phalloidin to conventional hippocampal slices to test whether induction of LTP by naturalistic patterns of afferent activity selectively increases actin polymerization in juvenile to young adult spines. Rhodamine-phalloidin, which selectively binds to polymerized actin, was detected in perikarya and proximal dendrites of CA1 pyramidal cells that received low-frequency afferent activity but was essentially absent in spines and fine dendritic processes. Theta pattern stimulation induced LTP and caused a large (threefold), reliable increase in labeled spines and spine-like puncta in the proximal dendritic zone containing potentiated synapses. The spines frequently occurred in the absence of labeling to other structures but were also found in association with fluorescent dendritic processes. These effects were replicated (> 10-fold increase in labeled spines) using extracellular applications of rhodamine-phalloidin. Increases in labeling appeared within 2 min, were completely blocked by treatments that prevent LTP induction, and occurred in slices prepared from young adult rats. These results indicate that near-threshold conditions for inducing stable potentiation cause the rapid polymerization of actin in mature spines and suggest that the effect is both sufficiently discrete to satisfy the synapse-specificity rule of LTP as well as rapid enough to participate in the initial stages of LTP consolidation.link_to_subscribed_fulltex
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