362 research outputs found
Local charge compensation from colour preconfinement as a key to the dynamics of hadronization
If, as is commonly accepted, the colour-singlet, `preconfined', perturbative
clusters are the primary units of hadronization, then the electric charge is
necessarily compensated locally at the scale of the typical cluster mass. As a
result, the minijet electric charge is suppressed at scales that are greater
than the cluster mass. We hence argue, and demonstrate by means of Monte Carlo
simulations using HERWIG, that the scale at which charge compensation is
violated is close to the mass of the clusters involved in hadronization, and
its measurement would provide a clue to resolving the nature of the dynamics.
We repeat the calculation using PYTHIA and find that the numbers produced by
the two generators are similar. The cluster mass distribution is sensitive to
soft emission that is considered unresolved in the parton shower phase. We
discuss how the description of the splitting of large clusters in terms of
unresolved emission modifies the algorithm of HERWIG, and relate the findings
to the yet unknown underlying nonperturbative mechanism. In particular, we
propose a form of that follows from a power-enhanced beta function,
and discuss how this that governs unresolved emission may be related
to power corrections. Our findings are in agreement with experimental data.Comment: 37 pages, 20 figure
Field theory description of vacuum replicas
In this paper we develop a systematic quantum field theory based approach to
the vacuum replica recently found to exist in effective low energy models in
hadronic physics. A local operator creating the replica state is constructed
explicitly. We show that a new effective quark-quark force arises in result of
replica existence. Phenomenological implications of such a force are also
briefly discussed.Comment: RevTeX4, 23 pages, 4 Postscript figures, uses epsfig.sty, to appear
in Phys.Rev.
Maternal Benzodiazepines and Z-Drugs Use during Pregnancy and Adverse Birth and Neurodevelopmental Outcomes in Offspring:A Population-Based Cohort Study
Introduction: The use of benzodiazepines and/or z-drugs in women of childbearing age has increased. Objective: The aim of the study was to evaluate whether gestational benzodiazepine and/or z-drug exposure is associated with adverse birth and neurodevelopmental outcomes. Methods: A population-based cohort including mother-child pairs from 2001 to 2018 in Hong Kong was analysed to compare gestationally exposed and nonexposed children on the risk of preterm birth, small for gestational age, autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD) through logistic/Cox proportional hazards regression with a 95% confidence interval (CI). Sibling-matched analyses and negative control analyses were applied. Results: When comparing gestationally exposed with gestationally nonexposed children, the weighted odds ratio (wOR) was 1.10 (95% CI = 0.97-1.25) for preterm birth and 1.03 (95% CI = 0.76-1.39) for small for gestational age, while the weighted hazard ratio (wHR) was 1.40 (95% CI = 1.13-1.73) for ASD and 1.15 (95% CI = 0.94-1.40) for ADHD. Sibling-matched analyses showed no association between gestationally exposed children and their gestationally nonexposed siblings for all outcomes (preterm birth: wOR = 0.84, 95% CI = 0.66-1.06; small for gestational age: wOR = 1.02, 95% CI = 0.50-2.09; ASD: wHR = 1.10, 95% CI = 0.70-1.72; ADHD: wHR = 1.04, 95% CI = 0.57-1.90). Similarly, no significant differences were observed when comparing children whose mothers took benzodiazepines and/or z-drugs during pregnancy to children whose mothers took benzodiazepines and/or z-drugs before but not during pregnancy for all outcomes. Conclusions: The findings do not support a causal relationship between gestational benzodiazepines and/or z-drugs exposure and preterm birth, small for gestational age, ASD, or ADHD. Clinicians and pregnant women should carefully balance the known risks of benzodiazepines and/or z-drugs use against those of untreated anxiety and sleep problems.</p
The check of QCD based on the tau-decay data analysis in the complex q^2-plane
The thorough analysis of the ALEPH data on hadronic tau-decay is performed in
the framework of QCD. The perturbative calculations are performed in 3 and
4-loop approximations. The terms of the operator product expansion (OPE) are
accounted up to dimension D=8. The value of the QCD coupling constant
alpha_s(m_tau^2)=0.355 pm 0.025 was found from hadronic branching ratio R_tau.
The V+A and V spectral function are analyzed using analytical properties of
polarization operators in the whole complex q^2-plane. Borel sum rules in the
complex q^2 plane along the rays, starting from the origin, are used. It was
demonstrated that QCD with OPE terms is in agreement with the data for the
coupling constant close to the lower error edge alpha_s(m_tau^2)=0.330. The
restriction on the value of the gluonic condensate was found
=0.006 pm 0.012 GeV^2. The analytical perturbative QCD was
compared with the data. It is demonstrated to be in strong contradiction with
experiment. The restrictions on the renormalon contribution were found. The
instanton contributions to the polarization operator are analyzed in various
sum rules. In Borel transformation they appear to be small, but not in spectral
moments sum rules.Comment: 24 pages; 1 latex + 13 figure files. V2: misprints are corrected,
uncertainty in alpha_s is explained in more transparent way, acknowledgement
is adde
On the Behavior of the Effective QCD Coupling alpha_tau(s) at Low Scales
The hadronic decays of the tau lepton can be used to determine the effective
charge alpha_tau(m^2_tau') for a hypothetical tau-lepton with mass in the range
0 < m_tau' < m_tau. This definition provides a fundamental definition of the
QCD coupling at low mass scales. We study the behavior of alpha_tau at low mass
scales directly from first principles and without any renormalization-scheme
dependence by looking at the experimental data from the OPAL Collaboration. The
results are consistent with the freezing of the physical coupling at mass
scales s = m^2_tau' of order 1 GeV^2 with a magnitude alpha_tau ~ 0.9 +/- 0.1.Comment: 15 pages, 4 figures, submitted to Physical Review D, added
references, some text added, no results nor figures change
Resummation of the hadronic tau decay width with the modified Borel transform method
A modified Borel transform of the Adler function is used to resum the
hadronic tau decay width ratio. In contrast to the ordinary Borel transform,
the integrand of the Borel integral is renormalization--scale invariant. We use
an ansatz which explicitly accounts for the structure of the leading infrared
renormalon. Further, we use judiciously chosen conformal transformations for
the Borel variable, in order to map sufficiently away from the origin the other
ultraviolet and infrared renormalon singularities. In addition, we apply Pade
approximants for the corresponding truncated perturbation series of the
modified Borel transform, in order to further accelerate the convergence.
Comparing the results with the presently available experimental data on the tau
hadronic decay width ratio, we obtain . These predictions
virtually agree with those of our previous resummations where we used ordinary
Borel transforms instead.Comment: 32 pages, 2 eps-figures, revtex; minor changes in the formulations; a
typo in Eq.(47) corrected; version as appearing in Phys. Rev.
A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses
We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants
The COMPASS Experiment at CERN
The COMPASS experiment makes use of the CERN SPS high-intensitymuon and
hadron beams for the investigation of the nucleon spin structure and the
spectroscopy of hadrons. One or more outgoing particles are detected in
coincidence with the incoming muon or hadron. A large polarized target inside a
superconducting solenoid is used for the measurements with the muon beam.
Outgoing particles are detected by a two-stage, large angle and large momentum
range spectrometer. The setup is built using several types of tracking
detectors, according to the expected incident rate, required space resolution
and the solid angle to be covered. Particle identification is achieved using a
RICH counter and both hadron and electromagnetic calorimeters. The setup has
been successfully operated from 2002 onwards using a muon beam. Data with a
hadron beam were also collected in 2004. This article describes the main
features and performances of the spectrometer in 2004; a short summary of the
2006 upgrade is also given.Comment: 84 papes, 74 figure
Tepotinib treatment in patients with MET exon 14-skipping non-small cell lung cancer: long-term follow-up of the VISION phase 2 nonrandomized clinical trial
IMPORTANCE MET inhibitors have recently demonstrated clinical activity in patients with MET exon 14 (METex14)-skipping non-small cell lung cancer (NSCLC); however, data with longer follow-up and in larger populations are needed to further optimize therapeutic approaches.OBJECTIVE To assess the long-term efficacy and safety of tepotinib, a potent and highly selective MET inhibitor, in patients with METex14-skipping NSCLC in the VISION study.DESIGN, SETTING, AND PARTICIPANTS The VISION phase 2 nonrandomized clinical trial was a multicohort, open-label, multicenter study that enrolled patients with METex14-skipping advanced/metastatic NSCLC (cohorts A and C) from September 2016 to May 2021. Cohort C (>18 months' follow-up) was an independent cohort, designed to confirm findings from cohort A (>35 months' follow-up). Data cutoff was November 20, 2022.INTERVENTION Patients received tepotinib, 500mg (450mg active moiety), once daily.MAIN OUTCOMES AND MEASURES The primary end point was objective response by independent review committee (RECIST v1.1). Secondary end points included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety.RESULTS Cohorts A and C included 313 patients (50.8% female, 33.9% Asian; median [range] age, 72 [41-94] years). The objective response rate (ORR) was 51.4%(95% CI, 45.8%-57.1%) with a median (m)DOR of 18.0 (95% CI, 12.4-46.4) months. In cohort C (n = 161), an ORR of 55.9%(95% CI, 47.9%-63.7%) with an mDOR of 20.8 (95% CI, 12.6-not estimable [NE]) months was reported across treatment lines, comparable to cohort A (n = 152). In treatment-naive patients (cohorts A and C; n = 164), ORR was 57.3%(95% CI, 49.4%-65.0%) and mDOR was 46.4 (95% CI, 13.8-NE) months. In previously treated patients (n = 149), ORR was 45.0% (95% CI, 36.8%-53.3%) and mDOR was 12.6 (95% CI, 9.5-18.5) months. Peripheral edema, the most common treatment-related adverse event, occurred in 210 patients (67.1%) (35 [11.2%] experienced grade >= 3 events).CONCLUSIONS AND RELEVANCE The findings from cohort C in this nonrandomized clinical trial supported the results from original cohort A. Overall, the long-term outcomes of VISION demonstrated robust and durable clinical activity following treatment with tepotinib, particularly in the treatment-naive setting, in the largest known clinical trial of patients with METex14-skipping NSCLC, supporting the global approvals of tepotinib and enabling clinicians to implement this therapeutic approach for such patients.Pathogenesis and treatment of chronic pulmonary disease
Strategies for Controlled Placement of Nanoscale Building Blocks
The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others
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