Semi-Inclusive Distributions in Statistical Models

The semi-inclusive properties of the system of neutral and charged particles with net charge equal to zero are considered in the grand canonical, canonical and micro-canonical ensembles as well as in micro-canonical ensemble with scaling volume fluctuations. Distributions of neutral particle multiplicity and charged particle momentum are calculated as a function of the number of charged particles. Different statistical ensembles lead to qualitatively different dependencies. They are being compared with the corresponding experimental data on multi-hadron production in $p+p$ interactions at high energies.Comment: Two subsections are added: "Average multiplicities, fluctuations and correlations" and "Quantum statistics

Power Law in Micro-Canonical Ensemble with Scaling Volume Fluctuations

Volume fluctuations are introduced in a statistical modelling of relativistic particle collisions. The micro-canonical ensemble is used, and the volume fluctuations are assumed to have the specific scaling properties. This leads to the KNO scaling of the particle multiplicity distributions as measured in p+p interactions. A striking prediction of the model is a power law form of the single particle momentum spectrum at high momenta. Moreover, the mean multiplicity of heavy particles also decreases as a function of the particle mass according to a power law. Finally, it is shown that the dependence of the momentum spectrum on the particle mass and momentum reduces to the dependence on the particle energy. These results resemble the properties of particle production in collisions of high energy particles

Charged-Particle Multiplicity in Proton-Proton Collisions

This article summarizes and critically reviews measurements of charged-particle multiplicity distributions and pseudorapidity densities in p+p(pbar) collisions between sqrt(s) = 23.6 GeV and sqrt(s) = 1.8 TeV. Related theoretical concepts are briefly introduced. Moments of multiplicity distributions are presented as a function of sqrt(s). Feynman scaling, KNO scaling, as well as the description of multiplicity distributions with a single negative binomial distribution and with combinations of two or more negative binomial distributions are discussed. Moreover, similarities between the energy dependence of charged-particle multiplicities in p+p(pbar) and e+e- collisions are studied. Finally, various predictions for pseudorapidity densities, average multiplicities in full phase space, and multiplicity distributions of charged particles in p+p(pbar) collisions at the LHC energies of sqrt(s) = 7 TeV, 10 TeV, and 14 TeV are summarized and compared.Comment: Invited review for Journal of Physics G -- version 2: version after referee's comment

Opportunities in multimodal neuroimaging for optimizing thrombolytic therapy for ischemic stroke

The main purpose of examination of patients before thrombolytic therapy for ischemic stroke (IS) is to timely identify contraindications to the use of recombinant tissue plasminogen activator.Objective: to estimate opportunities and benefits in applying multimodal magnetic resonance imaging (MRI) to improve clinical outcomes in acute stroke, among other processes, by enhancing the efficiency and safety of thrombolytic therapy.Patients and methods. The clinical experience of the S.M. Kirov Military Medical Academy in using multimodal MRI of the brain since 2004 was analyzed in patients with stroke.Results. Comprehensive assessment of the results of perfusion-weighted MRI of the brain and those of transcranial Doppler ultrasound identified five clinically significant variants of perfusion changes in IS: normal perfusion; postischemic hyperemia; persistent hypoperfusion; acute pathological hyperperfusion, and unrecovered perfusion. With an irreversible tissue damage volume of >60 cm3 on day 1 of stroke, as evidenced by diffusion-weighted MRI, the odd ratio for cerebral edema in the acutest period of the disease is 39.4% (95% CI 2.57–2436; p<0.05). The risk of hemorrhagic transformation increases with a measured diffusion coefficient in the area of the nucleus of developing nonlacunar infarct <35×10-5 mm2/sec within the first 24 hours after disease onset (p<0.005).Conclusion. The data of local clinical practice and the results of international clinical trials show that multimodal MRI of the brain is a reliable tool for the detailed evaluation of the expected efficiency and safety of thrombolytic therapy for IS. When persistent hypoperfusion is detected, the determination of perfusion-diffusion mismatch is of no informative value in deciding on whether thrombolytic therapy can be performed. Estimating the volume of pathological changes on diffusion-weighted images and the measured diffusion coefficient in the area of the nucleus of developing nonlacunar infarct in the measured diffusion coefficient maps allows the risk of major intracranial complications due to IS to be identified

Results of thrombectomy in lower-extremity ischemia in patients with COVID-19 and respiratory failure of different severity

Aim. To analyze the results of thrombectomy in lower-extremity ischemia in patients with coronavirus disease 2019 (COVID-19) and respiratory failure of different severity.Material and methods. This retrospective, cohort, comparative study for the period from May 1, 2020 to March 1, 2022 included 305 patients with acute lower-extremity ischemia and COVID-19. Depending on the type of oxygen support, three groups of patients were formed: group 1 (n=168) — nasal oxygen insufflation; group 2 (n=92) — non-invasive ventilation (NIV); group 3 (n=45) — artificial ventilation (AV). Thrombectomy was carried out according to the standard technique using Fogarty catheters (3F-6F — depending on the vessel size). After the diagnosis was established before and after the start of surgical treatment, all patients received the following therapy: Unfractionated IV heparin infusion at an initial rate of 1000 U/r, adjusted to maintain the activated partial thromboplastin time at 2-3 times the normal value; 2. Oral acetylsalicylic acid 125 mg; 3. Analgesics.Results. Myocardial infarction and ischemic stroke were not detected in the total sample. The highest number of deaths (group 1: 5,3%, n=9; group 2: 72,8%, n=67; group 3: 100%, n=45; p<0,0001), retrombosis (group 1 : 18,4%, n=31; group 2: 69,5%, n=64; group 3: 91,1%, n=41; p<0,0001) and limb amputations (group 1: 9,5%, n=16; group 2: 56,5%, n=52; group 3: 91,1%, n=41; p<0,0001) was recorded in group 3 patients.Conclusion. In patients receiving mechanical ventilation, COVID-19 have more aggressive course, which is expressed in an increase in laboratory para- meters (C-reactive protein, ferritin, interleukin-6, D-dimer), the severity of pneumonia and location of thrombosis in the tibial arteries. Among patients with COVID-19 receiving mechanical ventilation, the greatest number of rethromboses (91,1%), limb amputations (91,1%), and deaths (100%) are noted, which suggests the expediency of abandoning open thrombectomy in favor of anticoagulant/antiplatelet therapy in this cohort of patients. The development of arterial thrombosis in patients with COVID-19 receiving mechanical ventilation is an indicator of a high risk of death. Open thrombectomy in combination with anticoagulant/antiplatelet therapy is most effective in patients on nasal oxygen insufflation or NIV

Lambda hyperons produced in central nucleus-nucleus interactions at 4.5 GeV/c momentum per incident nucleon

Transverse momenta and rapidities of Lambda 's produced in central nucleus-nucleus collisions at 4.5 GeV/c·u (C-C,...,O-Pb) were studied and compared with those from inelastic He-Li interactions at the same incident momentum. Polarization of the Lambda hyperons was found to be consistent with zero ( alpha P=-0.06=0.11 for Lambda 's from central collisions). An upper limit of the Lambda -bar / Lambda production ratio was estimated to be less than 4.5 x 10-3. The experiment was performed in a triggered streamer chamber

Hadronization in Z0 decay

The confinement transition from the quark and gluon degrees of freedom appropriate in perturbation theory to the hadrons observed by real world experiments is poorly understood. In this strongly interacting transition regime we presently rely on models, which to varying degrees reflect possible scenarios for the QCD dynamics. Because of the absence of beam and target remnants, and the clean experimental conditions and high event rates, e+e- annihilation to hadrons at the Z0 provides a unique laboratory, both experimentally and theoretically, for the study of parton hadronization. This review discusses current theoretical understanding of the hadronization of partons, with particular emphasis on models of the non-perturbative phase, as implemented in Monte Carlo simulation programs. Experimental results at LEP and SLC are summarised and considered in the light of the models. Suggestions are given for further measurements which could help to produce more progress in understanding hadronization.Comment: Topical review, to appear in J.Phys.G, 80 page