Modeling state-selective photodetachment in cold ion traps: Rotational state "crowding" in small anions

Using accurate ab initio calculations of the interaction forces, we employ a quantum mechanical description of the collisional state-changing processes that occur in a cold ion trap with He as a buffer gas. We generate the corresponding inelastic rates for rotational transitions involving three simple molecular anions OH−(1Σ), MgH−(1Σ), and C2H−(1Σ) colliding with the helium atoms of the trap. We show that the rotational constants of these molecular anions are such that within the low-temperature regimes of a cold ion trap (up to about 50 K), a different proportion of molecular states are significantly populated when loading helium as a buffer gas in the trap. By varying the trap operating conditions, population equilibrium at the relevant range of temperatures is reached within different time scales. In the modeling of the photodetachment experiments, we analyze the effects of varying the chosen values for photodetachment rates as well as the laser photon fluxes. Additionally, the changing of the collision dynamics under different buffer gas densities is examined and the best operating conditions, for the different anions, for yielding higher populations of specific rotational states within the ion traps are extracted. The present modeling thus illustrates possible preparation of the trap conditions for carrying out more efficiently state-selected experiments with the trapped anions

Rotationally inelastic processes of C-2(-) ((2)Sigma(+)(g)) colliding with He (S-1) at low temperatures: ab initio interaction potential, state changing rates and kinetic modelling

We discuss in detail the quantum rotationally inelastic dynamics of an important anion often discussed as a possible constituent of the interstellar medium (ISM) and in different environments of circumstellar envelopes: the ${{\rm{C}}}_{2}^{-}$ molecular ion. Its interaction forces with one of the most abundant atoms of the ISM, the neutral helium atom, are obtained for the first time using ab initio quantum chemistry methods. The overall angular anisotropy of the potential energy surface is analysed in order to link its features with the efficiency of transferring energy from the abundant He atoms to the internal rotational levels of this molecular anion. Calculations of the corresponding rotational state-to-state inelastic cross sections, for both excitation and de-excitation paths are obtained by using a multichannel quantum method. The corresponding inelastic rates at the temperatures of interest are determined and their role in distributing molecular states over the different populations of the rotational levels at the temperatures of that environment is discussed. These computed rates are also linked to the dynamical behaviour of the title molecule when confined in cold ion traps and made to interact with He as the common buffer gas, in preparation for state-selective photo-detachment experiments

Cognitive loading affects motor awareness and movement kinematics but not locomotor trajectories during goal-directed walking in a virtual reality environment.

The primary purpose of this study was to investigate the effects of cognitive loading on movement kinematics and trajectory formation during goal-directed walking in a virtual reality (VR) environment. The secondary objective was to measure how participants corrected their trajectories for perturbed feedback and how participants' awareness of such perturbations changed under cognitive loading. We asked 14 healthy young adults to walk towards four different target locations in a VR environment while their movements were tracked and played back in real-time on a large projection screen. In 75% of all trials we introduced angular deviations of ±5° to ±30° between the veridical walking trajectory and the visual feedback. Participants performed a second experimental block under cognitive load (serial-7 subtraction, counter-balanced across participants). We measured walking kinematics (joint-angles, velocity profiles) and motor performance (end-point-compensation, trajectory-deviations). Motor awareness was determined by asking participants to rate the veracity of the feedback after every trial. In-line with previous findings in natural settings, participants displayed stereotypical walking trajectories in a VR environment. Our results extend these findings as they demonstrate that taxing cognitive resources did not affect trajectory formation and deviations although it interfered with the participants' movement kinematics, in particular walking velocity. Additionally, we report that motor awareness was selectively impaired by the secondary task in trials with high perceptual uncertainty. Compared with data on eye and arm movements our findings lend support to the hypothesis that the central nervous system (CNS) uses common mechanisms to govern goal-directed movements, including locomotion. We discuss our results with respect to the use of VR methods in gait control and rehabilitation

Electrophysiological Heterogeneity of Fast-Spiking Interneurons: Chandelier versus Basket Cells

In the prefrontal cortex, parvalbumin-positive inhibitory neurons play a prominent role in the neural circuitry that subserves working memory, and alterations in these neurons contribute to the pathophysiology of schizophrenia. Two morphologically distinct classes of parvalbumin neurons that target the perisomatic region of pyramidal neurons, chandelier cells (ChCs) and basket cells (BCs), are generally thought to have the same "fast-spiking" phenotype, which is characterized by a short action potential and high frequency firing without adaptation. However, findings from studies in different species suggest that certain electrophysiological membrane properties might differ between these two cell classes. In this study, we assessed the physiological heterogeneity of fast-spiking interneurons as a function of two factors: species (macaque monkey vs. rat) and morphology (chandelier vs. basket). We showed previously that electrophysiological membrane properties of BCs differ between these two species. Here, for the first time, we report differences in ChCs membrane properties between monkey and rat. We also found that a number of membrane properties differentiate ChCs from BCs. Some of these differences were species-independent (e.g., fast and medium afterhyperpolarization, firing frequency, and depolarizing sag), whereas the differences in the first spike latency between ChCs and BCs were species-specific. Our findings indicate that different combinations of electrophysiological membrane properties distinguish ChCs from BCs in rodents and primates. Such electrophysiological differences between ChCs and BCs likely contribute to their distinctive roles in cortical circuitry in each species. © 2013 Povysheva et al

Kinetic modelling of competition and depletion of shared miRNAs by competing endogenous RNAs

Non-conding RNAs play a key role in the post-transcriptional regulation of mRNA translation and turnover in eukaryotes. miRNAs, in particular, interact with their target RNAs through protein-mediated, sequence-specific binding, giving rise to extended and highly heterogeneous miRNA-RNA interaction networks. Within such networks, competition to bind miRNAs can generate an effective positive coupling between their targets. Competing endogenous RNAs (ceRNAs) can in turn regulate each other through miRNA-mediated crosstalk. Albeit potentially weak, ceRNA interactions can occur both dynamically, affecting e.g. the regulatory clock, and at stationarity, in which case ceRNA networks as a whole can be implicated in the composition of the cell's proteome. Many features of ceRNA interactions, including the conditions under which they become significant, can be unraveled by mathematical and in silico models. We review the understanding of the ceRNA effect obtained within such frameworks, focusing on the methods employed to quantify it, its role in the processing of gene expression noise, and how network topology can determine its reach.Comment: review article, 29 pages, 7 figure

Wild meat consumption in urban Sierra Leone during the Covid-19 pandemic

Wild meat is associated with an increased risk of zoonotic diseases. In some West African countries wild meat consumption declined as the result of official restrictions following Ebola outbreaks during 2013–2016, and was also affected by the current Covid-19 pandemic. In Sierra Leone, a country affected by these diseases, we documented wild meat use in four markets in the capital, Freetown. From a total of 197 interviews, we analysed the influence of age and gender on the types of wild meat eaten and the reasons for their consumption. We found that more men than women consumed wild meat, and for both genders taste was the main reason for eating wild meat. Age did not affect wild meat consumption amongst women. Evidence for changes in consumer behaviour in response to zoonotic disease risk was mixed. Although some consumers avoided wild meat because of disease risk, none stated this was the primary reason for not eating wild meat, and monkeys (presumed to carry a high zoonotic disease risk) were amongst the species cited as being consumed often. More work is needed to identify the best pathway towards safe and sustainable consumption of wild meat in urban Sierra Leone

A phase II trial of a biweekly combination of paclitaxel and gemcitabine in metastatic breast cancer

BACKGROUND: Many emerging new drugs have recently been trialled for treatment of early and advanced breast cancer. Among these new agents paclitaxel and gemcitabine play a crucial role, mostly in patients with relapsed and metastatic disease after failure of chemotherapy with antracyclines. METHODS: A phase II study was started in order to evaluate the activity and toxicity of a combination of paclitaxel and gemcitabine in a biweekly schedule on metastatic breast cancer patients previously treated with antracyclines. RESULTS: Twenty-five patients received paclitaxel (150 mg/mq) by 3-hours infusion, followed by gemcitabine (2000 mg/mq) given as a 60 min i.v. infusion (day 1–14) for a maximum of eight cycles. In all patients treatment was evaluated for toxicity and efficacy; four patients (16%) achieved a complete response, 12 (48%) a partial response giving an overall objective response rate of 64%. Stable disease was documented in 5 patients (20%) and progressive disease occurred in 4 patients (16%). CONCLUSION: The schedule of treatment was safe and tolerable from a haematological and non-haematological point of view. These data confirm that the combination of gemcitabine and paclitaxel on a biweekly basis is an effective and well-tolerated regimen in breast cancer patients with prior therapeutic exposure to antracyclines

Gastrointestinal complaints in runners are not due to small intestinal bacterial overgrowth

<p>Abstract</p> <p>Background</p> <p>Gastrointestinal complaints are common among long distance runners. We hypothesised that small intestinal bacterial overgrowth (SIBO) is present in long distance runners frequently afflicted with gastrointestinal complaints.</p> <p>Findings</p> <p>Seven long distance runners (5 female, mean age 29.1 years) with gastrointestinal complaints during and immediately after exercise without known gastrointestinal diseases performed Glucose hydrogen breath tests for detection of SIBO one week after a lactose hydrogen breath test checking for lactose intolerance. The most frequent symptoms were diarrhea (5/7, 71%) and flatulence (6/7, 86%). The study was conducted at a laboratory.</p> <p>In none of the subjects a pathological hydrogen production was observed after the intake of glucose. Only in one athlete a pathological hydrogen production was measured after the intake of lactose suggesting lactose intolerance.</p> <p>Conclusions</p> <p>Gastrointestinal disorders in the examined long distance runners were not associated with small intestinal bacterial overgrowth.</p