Dynamical clustering of counterions on flexible polyelectrolytes

Molecular dynamics simulations are used to study the local dynamics of counterion-charged polymer association at charge densities above and below the counterion condensation threshold. Surprisingly, the counterions form weakly-interacting clusters which exhibit short range orientational order, and which decay slowly due to migration of ions across the diffuse double layer. The cluster dynamics are insensitive to an applied electric field, and qualitatively agree with the available experimental data. The results are consistent with predictions of the classical theory only over much longer time scales

High-frequency percussive ventilation facilitates weaning from extracorporeal membrane oxygenation in adults

© 2018 American Society of Extra-Corporeal Technology. All Rights Reserved. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is an invaluable rescue therapy for patients suffering from cardiopulmonary arrest, but it is not without its drawbacks. There are cases where patients recover their cardiac function, yet they fail to wean to mechanical conventional ventilation (MCV). The use of high-frequency percussive ventilation (HFPV) has been described in patients with acute respiratory failure (RF) who fail MCV. We describe our experience with five patients who underwent VA-ECMO for cardiopulmonary arrest who were successfully weaned from VA-ECMO with HFPV after failure to wean with MCV. Weaning trials of HFPV a day before decannulation or at the time of separation from VA-ECMO were conducted. Primary endpoint data collected include pre- and post-HFPV partial pressures of oxygen (PaO2) and PaO2/FIO2(P/F) ratios measured at 2 and 24 hours after institution of HFPV. Additional periprocedural data points were collected including length of time on ECMO, hospital stay, and survival to discharge. Four of five patients were placed on VA-ECMO subsequent to percutaneous coronary intervention. One patient had cardiac arrest secondary to RF. Mean PaO2(44 ± 15.9 mmHg vs. 354 ± 149 mmHg, p \u3c .01) and mean P/F ratio (44 ± 15.9 vs. 354 ± 149, p \u3c .01) increased dramatically at 2 hours after the initiation of HFPV. Theimprovementinmean PaO2and P/F ratio was durable at 24 hours whether or not the patient was returned to MCV (n = 3) or remained on HFPV (n = 2) (44 ± 15.9 mmHg vs. 131 ± 68.7 mmHg, p = .036 and 44 ± 15.9 vs. 169 ± 69.9, p \u3c .01, respectively). Survival to discharge was 80%. The data presented suggest that HFPV may be used as a strategy to shorten time on ECMO, thereby reducing the negative effects of the ECMO circuit and improving its cost efficacy

Strongly Lensed Supermassive Black Hole Binaries as Nanohertz Gravitational-Wave Sources

Supermassive black hole binary systems (SMBHBs) should be the most powerful sources of gravitational waves (GWs) in the Universe. Once Pulsar Timing Arrays (PTAs) detect the stochastic GW background from their cosmic merger history, searching for individually resolvable binaries will take on new importance. Since these individual SMBHBs are expected to be rare, here we explore how strong gravitational lensing can act as a tool for increasing their detection prospects by magnifying fainter sources and bringing them into view. Unlike for electromagnetic waves, when the geometric optics limit is nearly always valid, for GWs the wave-diffraction-interference effects can become important when the wavelength of the GWs is larger than the Schwarzchild radius of the lens, i.e. $M_{\rm lens} \sim 10^8\,(\frac{f}{mHz})^{-1}\,M_\odot$. For the GW frequency range explored in this work, the geometric optics limit holds. We investigate GW signals from SMBHBs that might be detectable with current and future PTAs under the assumption that quasars serve as bright beacons that signal a recent merger. Using the black hole mass function derived from quasars and a physically motivated magnification distribution, we expect to detect a few strongly lensed binary systems out to $z \approx 2$. Additionally, for a range of fixed magnifications $2 \leq \mu \leq 100$, strong lensing adds up to $\sim$30 more detectable binaries for PTAs. Finally, we investigate the possibility of observing both time-delayed electromagnetic signals and GW signals from these strongly lensed binary systems -- that will provide us with unprecedented multimessenger insights into their orbital evolution.Comment: 13 pages, 7 figures (now 16 pages, 8 figures); updated method/results & pre-publication revisions, references adde

Цитокіновий профіль у вагітних з хламідійно-вірусною інфекцією

Урогенитальный хламидиоз и вирусная инфекция – это актуальная медико-социальная проблема, поэтому углубленные исследования клинических, иммунологических и эндокринологических аспектов этой проблемы у беременных, разработка и внедрение лечебно-профилактических программ является одним из перспективных резервов снижения репродуктивных потерь, материнской и перинатальной заболеваемости. Вместе с этим, такие исследования составляют значительный научный интерес и большую практическую ценность. При изучении механизмов осложнений беременности большой интерес вызывают исследования функционального состояния клеток ММС (путем определения уровня провоспалительных цитокинов ИЛ - 1β, ФНО -α), а также Т-лимфоцитов (путем определения провоспалительных цитокинов ИЛ -2, ИФН-γ и провоспалительных цитокинов ИЛ -4, ИЛ -10).Urogenital chlamydia and viral infection are actual medical and social problems. That is why the most promising reserves to reduce reproductive losses, maternal and perinatal morbidity are deep study of clinical, immunological, microbiological and endocrinological aspects of this problem among pregnant women, as well as developing and implementing of health care programs. Moreover, such studies have significant scientific interest and great practical value. While studying the mechanisms of pregnancy complications, the most interesting are the study of the functional state of MMS cells (by determining the level of proinflammatory cytokines IL-1β TNF-α), and T-lymphocytes (by determining the level of proinflammatory cytokines IL-2, IFN-γ and anti-inflammatory cytokines IL-4, IL-10)

Observation of gravitational waves from the coalescence of a 2.5–4.5 M ⊙ compact object and a neutron star

We report the observation of a coalescing compact binary with component masses 2.5–4.5 M ⊙ and 1.2–2.0 M ⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO–Virgo–KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M ⊙ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We provisionally estimate a merger rate density of 55−47+127Gpc−3yr−1 for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star–black hole merger, GW230529_181500-like sources may make up the majority of neutron star–black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star–black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap

High-Frequency Percussive Ventilation Rescue Therapy in Morbidly Obese Patients Failing Conventional Mechanical Ventilation.

Morbidly obese patients with respiratory failure who do not improve on conventional mechanical ventilation (CMV) often undergo rescue therapy with extracorporeal membrane oxygenation (ECMO). We describe our experience with high-frequency percussive ventilation (HFPV) as a rescue modality.In a retrospective analysis from 2009 to 2016, 12 morbidly obese patients underwent HFPV after failing to wean from CMV. Data were collected regarding demographics, cause of respiratory failure, ventilation settings, and hospital course outcomes. Our end point data were pre- and post-HFPV partial pressure of arterial oxygen and PaO2 to fraction of inspired oxygen (PF) ratios measured at initiation, 2, and 24 hours.Twelve morbidly obese patients required HFPV for respiratory failure. Causes of respiratory failure overlapped and included cardiogenic pulmonary edema (n = 8), pneumonia (n = 5), septic shock (n = 5), and asthma (n = 1). After HFPV initiation, mean fraction of inspired oxygen FiO2 was tapered from 98% to 82% and 66% at 2 and 24 hours, respectively. Mean PaO2 increased from 60.9 mm Hg before HFPV to 175.1 mm Hg ( P \u3c .05) at initiation of HFPV, then sustained at 129.5 mm Hg ( P \u3c .05) and 88.1 mm Hg ( P \u3c .005) at 2 and 24 hours, respectively. Mean PF ratio improved from 66.1 before HFPV to 180.3 ( P \u3c .05), 181.0 ( P \u3c .05) and 148.9 ( P \u3c .0005) at initiation, 2, and 24 hours, respectively. The improvement in mean PaO2 and PF ratios was durable at 24 hours whether or not the patient was returned to CMV (n = 10) or remained on HFPV (n = 2). Survival to discharge was 66.7%.In our cohort of morbidly obese patients, HFPV was successfully utilized as a rescue therapy precluding the need for ECMO. Despite our small sample size, HFPV should be considered as a rescue therapy in morbidly obese patients failing CMV prior to the initiation of ECMO. Our retrospective analysis supports consideration for HFPV as another form of rescue therapy for obese patients with refractory hypoxemia and respiratory failure who are not improving with CMV