187 research outputs found
The use of a 30-degree radiolucent triangle during surgery in distal avulsion fractures of the patella.
Avoiding patella baja or alta after the Krackow suture technique for distal avulsion fractures of the patella can be challenging. We aim to introduce a simple and reproducible technique using a 30-degree radiolucent triangle involving the contralateral knee to ensure the correct positioning of the patella intraoperatively.
The radiolucent triangle is positioned under the contralateral knee before operating the injured knee. A strict lateral view is obtained using fluoroscopy as a reference before a Krackow technique is performed on the avulsion fracture of the patella.
The triangle technique is straightforward and easily reproducible by surgeons of all levels. It allows the surgeon to correctly position the patella intraoperatively in avulsion fracture repair and modify tension on the patellar tendon.
This method avoids millimetric mispositioning of the operated patella, thus improving the management intraoperatively and could decrease postoperative complications
Ab initio calculations of the hydrogen bond
Recent x-ray Compton scattering experiments in ice have provided useful
information about the quantum nature of the interaction between HO
monomers. The hydrogen bond is characterized by a certain amount of charge
transfer which could be determined in a Compton experiment. We use ab-initio
simulations to investigate the hydrogen bond in HO structures by
calculating the Compton profile and related quantities in three different
systems, namely the water dimer, a cluster containing 12 water molecules and
the ice crystal. We show how to extract estimates of the charge transfer from
the Compton profiles.Comment: 16 pages, 7 figures, to appear in Phys. Rev.
Modelling the spectral evolution of classical double radio sources
The spectral evolution of powerful double radio galaxies (FR II's) is thought
to be determined by the acceleration of electrons at the termination shock of
the jet, their transport through the bright head region into the lobes and the
production of the radio emission by synchrotron radiation in the lobes. Models
presented to date incorporate some of these processes in prescribing the
electron distribution which enters the lobes. We have extended these models to
include a description of electron acceleration at the relativistic termination
shock and a selection of transport models for the head region. These are
coupled to the evolution of the electron spectrum in the lobes under the
influence of losses due to adiabatic expansion, by inverse Compton scattering
on the cosmic background radiation and by synchrotron radiation. The
evolutionary tracks predicted by this model are compared to observation using
the power/source-size (P-D) diagram. We find that the simplest scenario, in
which accelerated particles suffer adiabatic losses in the head region which
become more severe as the source expands produces P-D-tracks which conflict
with observation, because the power is predicted to decline too steeply with
increasing size. Agreement with observation can be found by assuming that
adiabatic losses are compensated during transport between the termination shock
and the lobe by a re-acceleration process distributed throughout the head
region.Comment: 14 pages, 6 figures, accepted for publication in Astronomy and
Astrophysic
Positron transport in the interstellar medium
We seek to understand the propagation mechanisms of positrons in the
interstellar medium (ISM). This understanding is a key to determine whether the
spatial distribution of the annihilation emission observed in our Galaxy
reflects the spatial distribution of positron sources and, therefore, makes it
possible to place constraints on the origin of positrons. We review the
different processes that are likely to affect the transport of positrons in the
ISM. These processes fall into three broad categories: scattering off
magnetohydrodynamic waves, collisions with particles of the interstellar gas
and advection with large-scale fluid motions. We assess the efficiency of each
process and describe its impact on the propagation of positrons. We also
develop a model of positron propagation, based on Monte-Carlo simulations,
which enable us to estimate the distances traveled by positrons in the
different phases of the ISM. We find that low-energy (< 10 MeV) positrons
generally have negligible interactions with magnetohydrodynamic waves, insofar
as these waves are heavily damped. Positron propagation is mainly controlled by
collisions with gas particles. Under these circumstances, positrons can travel
huge distances (up to 30 kpc/n_H for 1 MeV positrons) along magnetic field
lines before annihilating.Comment: 18 pages, 12 figures, accepted in Astronomy and Astrophysic
Disease Rescue and Increased Lifespan in a Model of Cardiomyopathy and Muscular Dystrophy by Combined AAV Treatments
The BIO14.6 hamster is an excellent animal model for inherited cardiomyopathy, because of its lethal and well-documented course, due to a spontaneous deletion of delta-sarcoglycan gene promoter and first exon. The muscle disease is progressive and average lifespan is 11 months, because heart slowly dilates towards heart failure.Based on the ability of adeno-associated viral (AAV) vectors to transduce heart together with skeletal muscle following systemic administration, we delivered human delta-sarcoglycan cDNA into male BIO14.6 hamsters by testing different ages of injection, routes of administration and AAV serotypes. Body-wide restoration of delta-SG expression was associated with functional reconstitution of the sarcoglycan complex and with significant lowering of centralized nuclei and fibrosis in skeletal muscle. Motor ability and cardiac functions were completely rescued. However, BIO14.6 hamsters having less than 70% of fibers recovering sarcoglycan developed cardiomyopathy, even if the total rescued protein was normal. When we used serotype 2/8 in combination with serotype 2/1, lifespan was extended up to 22 months with sustained heart function improvement.Our data support multiple systemic administrations of AAV as a general therapeutic strategy for clinical trials in cardiomyopathies and muscle disorders
Pharmacist intervention program to enhance hypertension control: a randomised controlled trial
Objective Studies have demonstrated that hypertension remains inadequately managed throughout the world, with lack of adherence to BP-lowering medication being a major factor. The aim of the present study was to evaluate if a pharmaceutical care program could improve antihypertensive medication adherence and blood pressure control. Setting This study was conducted in a secondary care hypertension/dyslipidemia outpatient clinic in the university teaching hospital of Cova da Beira Hospital Centre, Covilhã, located in the Eastern Central Region of Portugal. Method This report evaluates the pharmacist’s interventions during a prospective randomised controlled trial, from July 2009 to June 2010. Patients with diagnosis of essential hypertension attending the clinic for routine follow-up were randomly allocated either to a control group (no pharmaceutical care) or to an intervention group (quarterly follow-up by a hospital pharmacist during a 9-month period). The pharmacist interventions, aimed to increase medication adherence and blood pressure control, involved educational interventions and counselling tips directed to the patient. Main outcome measure Systolic blood pressure, diastolic blood pressure and blood pressure control (according to JNC 7 guidelines) assessed at the baseline visit and at the end of pharmaceutical care were the main outcome measures. Blood pressure measurements were performed by blinded nurses. Medication adherence was also evaluated, using a validated questionnaire at baseline and at the end of investigation. Results A total of 197 hypertensive patients were randomly assigned to the study (99 in the control group and 98 in the intervention group). Although there were no significant differences (P > 0.05) in both groups concerning mean age, gender, body mass index, and antihypertensive pharmacotherapy, blood pressure control was higher in the intervention group (P = 0.005) at the end of the study. Significant lower systolic blood pressure (−6.8 mmHg, P = 0.006) and diastolic blood pressure (−2.9 mmHg, P = 0.020) levels were observed in the intervention group. Medication adherence was also significantly higher in the intervention group at the end of the study (74.5% vs. 57.6%, P = 0.012).Conclusion Pharmacist intervention can significantly improve medication adherence and blood pressure control in patients treated with antihypertensive agents
Evidence for Nearby Supernova Explosions
Supernova explosions are one of the most energetic--and potentially
lethal--phenomena in the Universe. Scientists have speculated for decades about
the possible consequences for life on Earth of a nearby supernova, but
plausible candidates for such an event were lacking. Here we show that the
Scorpius-Centaurus OB association, a group of young stars currently located
at~130 parsecs from the Sun, has generated 20 SN explosions during the last 11
Myr, some of them probably as close as 40 pc to our planet. We find that the
deposition on Earth of 60Fe atoms produced by these explosions can explain the
recent measurements of an excess of this isotope in deep ocean crust samples.
We propose that ~2 Myr ago, one of the SNe exploded close enough to Earth to
seriously damage the ozone layer, provoking or contributing to the
Pliocene-Pleistocene boundary marine extinction.Comment: 4 pages, 2 figures. Replaced by final version to appear in Physical
Review Letter
Insights on the Neuromagnetic Representation of Temporal Asymmetry in Human Auditory Cortex.
Communication sounds are typically asymmetric in time and human listeners are highly sensitive to this short-term temporal asymmetry. Nevertheless, causal neurophysiological correlates of auditory perceptual asymmetry remain largely elusive to our current analyses
and models. Auditory modelling and animal electrophysiological recordings suggest that perceptual asymmetry results from the presence of multiple time scales of temporal integration, central to the auditory periphery. To test this hypothesis we recorded auditory evoked fields (AEF) elicited by asymmetric sounds in humans. We found a strong correlation between perceived tonal salience of ramped and damped sinusoids and the AEFs, as quantified by the amplitude of the N100m dynamics. The N100m amplitude increased with stimulus
half-life time, showing a maximum difference between the ramped and damped stimulus for a modulation half-life time of 4 ms which is greatly reduced at 0.5 ms and 32 ms. This behaviour of the N100m closely parallels psychophysical data in a manner that: i) longer
half-life times are associated with a stronger tonal percept, and ii) perceptual differences between damped and ramped are maximal at 4 ms half-life time. Interestingly, differences in evoked fields were significantly stronger in the right hemisphere, indicating some degree of hemispheric specialisation. Furthermore, the N100m magnitude was successfully
explained by a pitch perception model using multiple scales of temporal integration of auditory
nerve activity patterns. This striking correlation between AEFs, perception, and model predictions suggests that the physiological mechanisms involved in the processing of pitch evoked by temporal asymmetric sounds are reflected in the N100m
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