2,274 research outputs found
General models of Einstein gravity with a non-Newtonian weak-field limit
We investigate Einstein theories of gravity, coupled to a scalar field \vphi
and point-like matter, which are characterized by a scalar field-dependent
matter coupling function e^{H(\vphi)}. We show that under mild constraints on
the form of the potential for the scalar field, there are a broad class of
Einstein-like gravity models -characterized by the asymptotic behavior of H-
which allow for a non-Newtonian weak-field limit with the gravitational
potential behaving for large distances as ln r. The Newtonian term GM/r appears
only as sub-leading. We point out that this behavior is also shared by gravity
models described by f(R) Lagrangians. The relevance of our results for the
building of infrared modified theories of gravity and for modified Newtonian
dynamics is also discussed.Comment: 9 page
Dynamical screening in strongly correlated metal SrVO3
The consequences of dynamical screening of Coulomb interaction among
correlated electrons in realistic materials have not been widely considered
before. In this letter we try to incorporate a frequency dependent Coulomb
interaction into the state-of-the-art ab initio electronic structure computing
framework of local density approximation plus dynamical mean-field theory, and
then choose SrVO3 as a prototype material to demonstrate the importance of
dynamical screening effect. It is shown to renormalise the spectral weight near
the Fermi level, to increase the effective mass, and to suppress the t2g
quasiparticle band width apparently. The calculated results are in accordance
with very recent angle-resolved photoemission spectroscopy experiments and Bose
factor ansatz calculations.Comment: 6 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1107.312
Osmotic behaviour of human mesenchymal stem cells: implications for cryopreservation
Aimed at providing a contribution to the optimization of cryopreservation processes, the present work focuses on the osmotic behavior of human mesenchymal stem cells (hMSCs). Once isolated from the umbilical cord blood (UCB) of three different donors, hMSCs were characterized in terms of size distribution and their osmotic properties suitably evaluated through the exposure to hypertonic and isotonic aqueous solutions at three different temperatures. More specifically, inactive cell volume and cell permeability to water and di-methyl sulfoxide (DMSO) were measured, being cell size determined using impedance measurements under both equilibrium and dynamic conditions. Experimental findings indicate that positive cell volume excursions are limited by the apparent increase of inactive volume, which occurs during both the shrink-swell process following DMSO addition and the subsequent restoration of isotonic conditions in the presence of hypertonic solutions of impermeant or permeant solutes. Based on this evidence, hMSCs must be regarded as imperfect osmometers, and their osmotic behavior described within a scenario no longer compatible with the simple two-parameter model usually utilized in the literature. In this respect, the activation of mechano-sensitive ion-channels seemingly represents a reasonable hypothesis for rationalizing the observed osmotic behavior of hMSCs from UCB
Geographical Variation in Medication Prescriptions: A Multiregional Drug-Utilization Study
Background: Studies have emphasized the importance of geographical factors and general practitioner (GP) characteristics in influencing drug prescriptions. Objectives: To: (i) ascertain the prevalence rate (PR) of use of drugs in six therapeutic categories used for chronic conditions; (ii) assess how geographical characteristics and GP characteristics may influence drug prescribing. Methods: This study is part of the EDU.RE.DRUG Project, a national collaborative project founded by Italian Medicine Agency (AIFA). Cross-sectional analyses were undertaken employing the pharmacy-claim databases of four local health units (LHUs) located in two Italian regions: Lombardy and Campania. Six drug categories were evaluated: proton-pump inhibitors; antibiotics; respiratory-system drugs; statins; agents acting on the renin 12angiotensin system; psychoanaleptic drugs. The PR was estimated according to drug categories at the LHU level. A linear multivariate regression analysis was undertaken to evaluate the association between the PR and geographical area, age and sex of GPs, number of patients, and percentage of patients aged >65 per GP. Results: LHUs in Campania showed a PR that was significantly higher than that in Lombardy. Antibiotics showed the highest PR in all the LHUs assessed, ranging from 32.5% in Lecco (Lombardy) to 59.7% in Naples-2 (Campania). Multivariate linear regression analysis confirmed the association of the PR with geographical area for all drug categories. Being located in Campania increased the possibility of receiving a drug prescription from the categories considered, with estimates more marked for antibiotics, proton-pump-inhibitors, and respiratory-system drugs. Conclusions: This study provides information about the PR of medications used for treating common and costly conditions in Italy and highlighted a significant geographical variation. These insights could help to develop area-specific strategies to optimize prescribing behavior
Variability and predictors of response to continuous theta burst stimulation: a TMS-EEG study
Continuous theta-burst stimulation (cTBS) is a repetitive transcranial magnetic stimulation paradigm reported to decrease the excitability of the stimulated cortical area and which is thought to reflect a form of inhibitory synaptic plasticity. However, since its introduction, the effect of cTBS has shown a remarkable variability in its effects, which are often quantified by measuring the amplitude of motor evoked potentials (MEPs). Part of this inconsistency in experimental results might be due to an intrinsic variability of TMS effects caused by genetic or neurophysiologic factors. However, it is also possible that MEP only reflect the excitability of a sub-population of output neurons; resting EEG power and measures combining TMS and electroencephalography (TMS-EEG) might represent a more thorough reflection of cortical excitability. The aim of the present study was to verify the robustness of several predictors of cTBS response, such as I wave recruitment and baseline MEP amplitude, and to test cTBS after-effects on multiple neurophysiologic measurements such as MEP, resting EEG power, local mean field power (LMFP), TMS-related spectral perturbation (TRSP), and inter-trial phase clustering (ITPC). As a result, we were not able to confirm either the expected decrease of MEP amplitude after cTBS or the ability of I wave recruitment and MEP amplitude to predict the response to cTBS. Resting EEG power, LMFP, TRSP, and ITPC showed a more consistent trend toward a decrease after cTBS. Overall, our data suggest that the effect of cTBS on corticospinal excitability is variable and difficult to predict with common electrophysiologic markers, while its effect might be clearer when probed with combined TMS and EEG
Milk cathelicidin and somatic cell counts in dairy goats along the course of lactation
This research communication reports the evaluation of cathelicidin in dairy goat milk for its relationship with the somatic cell count (SCC) and microbial culture results. Considering the limited performances of SCC for mastitis monitoring in goats, there is interest in evaluating alternative diagnostic tools. Cathelicidin is an antimicrobial protein involved in innate immunity of the mammary gland. In this work, half-udder milk was sampled bimonthly from a herd of 37 Alpine goats along an entire lactation and tested with the cathelicidin ELISA together with SCC and bacterial culture. Cathelicidin and SCC showed a strong correlation (r = 0.72; n = 360 milk samples). This was highest in mid-lactation (r = 0.83) and lowest in late lactation (r = 0.61), and was higher in primiparous (0.80, n = 130) than in multiparous goats (0.71, n = 230). Both markers increased with stage of lactation, but cathelicidin increased significantly less than SCC. Inaddition, peak level in late lactation was lower for cathelicidin (5.05-fold increase) than for SCC (7.64-fold increase). Twenty-one (5.8%) samples were positive to bacteriological culture, 20 for coagulase-negative staphylococci and one for Streptococcus spp.; 18 of them were positive to the cathelicidin ELISA (85.71% sensitivity). Sensitivity of SCC >500 000 and of SCC >1 000 000 cells/ml was lower (71.43 and 23.81%, respectively). Therefore, the high correlation of cathelicidin with SCC during the entire lactation, along with its lower increase in late lactation and good sensitivity indetecting intramammary infection (IMI), indicate a potential for monitoring subclinical mastitis in dairy goats. However, based on this preliminary assessment, specificity should be improved (40.41% for cathelicidin vs. 54.57 and 67.85% for SCC >500 000 and >1 000 000 cells/ml, respectively). Therefore, the application of cathelicidin for detecting goat IMI will require further investigation and optimization, especially concerning the definition of diagnostic thresholds
Pair formation and collapse in imbalanced Fermion populations with unequal masses
We present an exact Quantum Monte Carlo study of the effect of unequal masses
on pair formation in Fermionic systems with population imbalance loaded into
optical lattices. We have considered three forms of the attractive interaction
and find in all cases that the system is unstable and collapses as the mass
difference increases and that the ground state becomes an inhomogeneous
collapsed state. We also address the question of canonical vs grand canonical
ensemble and its role, if any, in stabilizing certain phases
Disentangling EEG responses to TMS due to cortical and peripheral activations
Background: the use of combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) for the functional evaluation of the cerebral cortex in health and disease is becoming increasingly common. However, there is still some ambiguity regarding the extent to which brain responses to auditory and somatosensory stimulation contribute to the TMS-evoked potential (TEP). Objective/Hypothesis: to measure separately the contribution of auditory and somatosensory stimulation caused by TMS, and to assess their contribution to the TEP waveform, when stimulating the motor cortex (M1). Methods: 19 healthy volunteers underwent 7 blocks of EEG recording. To assess the impact of auditory stimulation on the TEP waveform, we used a standard figure of eight coil, with or without masking with a continuous noise reproducing the specific time-varying frequencies of the TMS click, stimulating at 90% of resting motor threshold. To further characterise auditory responses due to the TMS click, we used either a standard or a sham figure of eight coil placed on a pasteboard cylinder that rested on the scalp, with or without masking. Lastly, we used electrical stimulation of the scalp to investigate the possible contribution of somatosensory activation. Results: auditory stimulation induced a known pattern of responses in electrodes located around the vertex, which could be suppressed by appropriate noise masking. Electrical stimulation of the scalp alone only induced similar, non-specific scalp responses in the in the central electrodes. TMS, coupled with appropriate masking of sensory input, resulted in specific, lateralized responses at the stimulation site, lasting around 300 ms. Conclusions: if careful control of confounding sources is applied, TMS over M1 can generate genuine, lateralized EEG activity. By contrast, sensory evoked responses, if present, are represented by non-specific, late (100–200 ms) components, located at the vertex, possibly due to saliency of the stimuli. Notably, the latter can confound the TEP if masking procedures are not properly used
Disentangling EEG responses to TMS due to cortical and peripheral activations
BACKGROUND: the use of combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) for the functional evaluation of the cerebral cortex in health and disease is becoming increasingly common. However, there is still some ambiguity regarding the extent to which brain responses to auditory and somatosensory stimulation contribute to the TMS-evoked potential (TEP). OBJECTIVE/HYPOTHESIS: to measure separately the contribution of auditory and somatosensory stimulation caused by TMS, and to assess their contribution to the TEP waveform, when stimulating the motor cortex (M1). METHODS: 19 healthy volunteers underwent 7 blocks of EEG recording. To assess the impact of auditory stimulation on the TEP waveform, we used a standard figure of eight coil, with or without masking with a continuous noise reproducing the specific time-varying frequencies of the TMS click, stimulating at 90% of resting motor threshold. To further characterise auditory responses due to the TMS click, we used either a standard or a sham figure of eight coil placed on a pasteboard cylinder that rested on the scalp, with or without masking. Lastly, we used electrical stimulation of the scalp to investigate the possible contribution of somatosensory activation. RESULTS: auditory stimulation induced a known pattern of responses in electrodes located around the vertex, which could be suppressed by appropriate noise masking. Electrical stimulation of the scalp alone only induced similar, non-specific scalp responses in the in the central electrodes. TMS, coupled with appropriate masking of sensory input, resulted in specific, lateralized responses at the stimulation site, lasting around 300Â ms. CONCLUSIONS: if careful control of confounding sources is applied, TMS over M1 can generate genuine, lateralized EEG activity. By contrast, sensory evoked responses, if present, are represented by non-specific, late (100-200Â ms) components, located at the vertex, possibly due to saliency of the stimuli. Notably, the latter can confound the TEP if masking procedures are not properly used
A pragmatic controlled trial to improve the appropriate prescription of drugs in adult outpatients: Design and rationale of the EDU.RE.DRUG study
Introduction: Pharmacological intervention is an important component of patient care.
However, drugs are often inappropriately used. It is necessary for countries to implement
strategies to improve the rational use of drugs, including independent information for
healthcare professionals and the public, which must be supported by well-trained staff. The
primary objectives of the EDU.RE.DRUG (Effectiveness of informative and/or educational
interventions aimed at improving the appropriate use of drugs designed for general
practitioners and their patients) study are the retrospective evaluation of rates of
appropriate prescribing indicators (APIs) and the assessment of the effectiveness of informative
and/or educational interventions addressed to general practitioners (GPs) and their patients,
aimed at improving prescribing quality and promoting proper drug use. Methods and analysis:
This is a prospective, multicentre, open-label, parallel-arm, controlled, pragmatic trial directed
to GPs and their patients in two Italian regions (Campania and Lombardy). The study data are
retrieved from administrative databases (Demographic, Pharmacy-refill, and Hospitalization
databases) containing healthcare information of all beneficiaries of the National Health
Service in the Local Health Units (LHUs) involved. According to LHU, the GPs/patients will
be assigned to one of the following four intervention arms: (1) intervention on GPs and patients;
(2) intervention on GPs; (3) intervention on patients; and (4) no intervention (control). The
intervention designed for GPs consists of reports regarding the status of their patients according
to the APIs determined at baseline and in two on-line Continuous Medical Education (CME)
courses. The intervention designed for patients consists in flyers and posters distributed in GPs
ambulatories and community pharmacies, focusing on correct drug use.
A set of indicators (such as potential drug–drug interactions, unnecessary duplicate
prescriptions, and inappropriate prescriptions in the elderly), adapted to the Italian
setting, has been defined to determine inappropriate prescription at baseline and after the
intervention phase. The primary outcome was a composite API. Ethics and dissemination:
The study was approved by the Ethics Committee of the University of Milan on 7th June
2017 (code 15/17). The investigators will communicate trial results to stakeholders, collaborators, and participants via appropriate presentations and publications.
Registration details: NCT04030468. EudraCT number 2017-002622-2
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