335 research outputs found
Specialization versus diversification in research activities: the extent, intensity and relatedness of field diversification by individual scientists
Accreting Millisecond X-Ray Pulsars
Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories
without parallel in the study of extreme physics. In this chapter we review the
past fifteen years of discoveries in the field. We summarize the observations
of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength
observations that have been carried out since the discovery of the first AMXP
in 1998. We review accretion torque theory, the pulse formation process, and
how AMXP observations have changed our view on the interaction of plasma and
magnetic fields in strong gravity. We also explain how the AMXPs have deepened
our understanding of the thermonuclear burst process, in particular the
phenomenon of burst oscillations. We conclude with a discussion of the open
problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations
and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer;
[revision with literature updated, several typos removed, 1 new AMXP added
Laboratory evaluation on the characteristics and pollutant emissions of nanoclay and chemical warm mix asphalt modified binders
This study was conducted to investigate the performance characteristics of nanoclay- and chemical warm-mix asphalt (WMA) additive-modified asphalt binders in terms of their chemical, morphology, rheological and surface energy properties in comparison to conventional asphalt binder. Both the nanoclay modified asphalt binder (NCMB B) and the chemical WMA additive modified asphalt binder (CWAA) were artificially aged under short-term and long-term aging conditions prior to evaluation. The chemical and morphological properties were measured with Fourier Transform Infrared (FTIR) spectroscopy and Field-Emission Scanning Electron Microscopy (FE-SEM) respectively. Rheological eval-uations were conducted to determine binderâs behavior under short-term aging in terms of frequency sweep, temperature sweep, and creep recovery tests by utilizing the dynamic shear rheometer (DSR) machine. Emission test was also conducted on the unmodified and modified WMA mixtures to estimate the gaseous pollutants emitted during their manufacture. FTIR spectroscopy results showed that the addition of WMA modifiers into asphalt binder could delay and weaken the oxidation reaction of the binder which in turn improved the aging process. However, the physical structure did not seem to show any changes after undergoing long term aging. The use of NCMB B 4% (by weight of asphalt binder) seemed to produce better resistance towards rutting when compared to CWAA 1%, 2% and 3% for unaged, and short- and long-term aging test conditions. The modified binders exhibit significantly higher surface energy and hence produced good adhesion between aggregates, which imply increased resistance toward moisture-induced damage. This study also revealed that the manufacture of WMA mixtures reduced up to 50% of the pollutants emitted during mixing in laboratory
Effects of Cetuximab and Erlotinib on the behaviour of cancer stem cells in head and neck squamous cell carcinoma.
The therapeutic responses of many solid tumours to chemo- and radio-therapies are far from fully effective but therapies targeting malignancy-related cellular changes show promise for further control. In head and neck squamous cell carcinoma, the epidermal growth factor receptor (EGFR) is commonly overexpressed and investigation of agents that block this receptor indicate a limited response when used alone but an ability to enhance the actions of other drugs. The hierarchical stem cell patterns present in tumours generate cellular heterogeneity and this is further complicated by cancer stem cells (CSC) shifting between epithelial (Epi-CSC) and mesenchymal (EMT-CSC) states. To clarify how such heterogeneity influences responses to EGFR blocking, we examined the effects of Cetuximab and Erlotinib on the cell sub-populations in HNSCC cell lines. These agents reduced cell proliferation for all subpopulations but induced little cell death. They did however induce large shifts of cells between the EMT-CSC, Epi-CSC and differentiating cell compartments. Loss of EMT-CSCs reduced cell motility and is expected to reduce invasion and metastasis. EGFR blocking also induced shifts of Epi-CSCs into the differentiating cell compartment which typically has greater sensitivity to chemo/radiation, an effect expected to enhance the overall response of tumour cell populations to adjunctive therapies.This work was supported by the National Centre for
the Replacement, Refinement and Reduction of Animals
in Research (NC3Rs, Grant number: NC/L00061X/1),
by The SĂŁo Paulo Research Foundation (FAPESP Grant
numbers 2014/12658-3 and 2011/21395-8), and by the
Barts and The London Charitable Foundation
MIR137 is the key gene mediator of the syndromic obesity phenotype of patients with 1p21.3 microdeletions.
BACKGROUND: Deletions in the long arm of chromosome 1 have been described in patients with a phenotype consisting primarily of obesity, intellectual disability and autism-spectrum disorder. The minimal region of overlap comprises two genes: DPYD and MIR137. CASE PRESENTATION: We describe a 10-year-old boy with syndromic obesity who carries a novel 1p21.3Â deletion overlapping the critical region with the MIR137 gene only. CONCLUSIONS: This study suggests that MIR137 is the mediator of the obesity phenotype of patients carrying 1p21.3 microdeletions
Pedometer use and self-determined motivation for walking in a cardiac telerehabilitation program: a qualitative study
BACKGROUND: Exercise-based cardiac rehabilitation reduces morbidity and mortality. Walking is a convenient activity suitable for people with cardiac disease. Pedometers count steps, measure walking activity and motivate people to increase physical activity. In this study, patients participating in cardiac telerehabilitation were provided with a pedometer to support motivation for physical activity with the purpose of exploring pedometer use and self-determined motivation for walking experienced by patients and health professionals during a cardiac telerehabilitation program. METHODS: A qualitative research design consisting of observations, individual interviews and patient documents made the basis for a content analysis. Data was analysed deductively using Self Determination Theory as a frame for analysis and discussion, focusing on the psychological needs of autonomy, competence and relatedness. Twelve cardiac patients, 11 health professionals, 6 physiotherapists and 5 registered nurses were included. RESULTS: The pedometer offered independence from standardised rehabilitation since the pedometer supported tailoring, individualised walking activity based on the patientâs choice. This led to an increased autonomy. The patients felt consciously aware of health benefits of walking, and the pedometer provided feedback on walking activity leading to an increased competence to achieve goals for steps. Finally, the pedometer supported relatedness with others. The health professionalsâ surveillance of patientsâ steps, made the patients feel observed, yet supported, furthermore, their next of kin appeared to be supportive as walking partners. CONCLUSION: Cardiac patientsâ motivation for walking was evident due to pedometer use. Even though not all aspects of motivation were autonomous and self determined, the patients felt motivated for walking. The visible steps and continuous monitoring of own walking activity made it possible for each individual patient to choose their desired kind of activity and perform ongoing adjustments of walking activity. The immediate feedback on step activity and the expectations of health benefits resulted in motivation for walking. Finally, pedometer supported walking made surveillance possible, giving the patients a feeling of being looked after and supported. TRIAL REGISTRATION: Current study is a part of The Teledi@log project
Muscle activation during gait in children with Duchenne muscular dystrophy
The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity
Characterization of SABRE crystal NaI-33 with direct underground counting
Published online: 09 April 2021Ultra-pure NaI(Tl) crystals are the key element for a model-independent verification of the long standing DAMA result and a powerful means to search for the annual modulation signature of dark matter interactions. The SABRE collaboration has been developing cutting-edge techniques for the reduction of intrinsic backgrounds over several years. In this paper we report the first characterization of a 3.4 kg crystal, named NaI-33, performed in an underground passive shielding setup at LNGS. NaI-33 has a record low ÂłâčK contamination of 4.3 ± 0.2 ppb as determined by mass spectrometry. We measured a light yield of 11.1 ± 0.2 photoelectrons/keV and an energy resolution of 13.2% (FWHM/E) at 59.5 keV. We evaluated the activities of ÂČÂČâ¶Ra and ÂČÂČâžTh inside the crystal to be 5.9±0.6 ÎŒBq/kg and 1.6±0.3 ÎŒBq/kg, respectively, which would indicate a contamination from ÂČÂłâžU and ÂČÂłÂČTh at part-per-trillion level. We measured an activity of 0.51 ± 0.02 mBq/kg due to ÂČÂčâ°Pb out of equilibrium and a α quenching factor of 0.63 ± 0.01 at 5304 keV. We illustrate the analyses techniques developed to reject electronic noise in the lower part of the energy spectrum. A cut-based strategy and a multivariate approach indicated a rate, attributed to the intrinsic radioactivity of the crystal, of âŒ1 count/day/kg/keV in the [5â20] keV region.M. Antonello ... I. Bolognino ... A. G. Williams ... et al
Internet-based guided self-help for glioma patients with depressive symptoms: a randomized controlled trial
Depressive symptoms are common in glioma patients, and can negatively affect health-related quality of life (HRQOL). We performed a nation-wide randomized controlled trial to evaluate the effects of an online guided self-help intervention for depressive symptoms in adult glioma patients. Glioma patients with depressive symptoms were randomized to a 5-week online course based on problem-solving therapy, or a waiting list control group. After having received the intervention, the glioma patient groups combined were compared with patients with cancer outside the central nervous system (non-CNS cancer controls), who also received the intervention. Sample size calculations yielded 63 participants to be recruited per arm. The primary outcome [depressive symptoms (CES-D)] and secondary outcomes [fatigue (Checklist Individual Strength (CIS)) and HRQOL (Short Form-36)], were assessed online at baseline, post-intervention, and 3 and 12 months follow-up. In total, 89 glioma patients (intervention Nâ=â45; waiting list Nâ=â44) and 26 non-CNS cancer controls were included, of whom 35 and 54% completed the intervention, respectively. Recruitment could not be extended beyond 3.5 years due to funding. On depression, no statistically significant differences between the groups were found. Fatigue decreased post-treatment in the glioma intervention group compared with the waiting list group (pâ=â0.054, dâ=â0.306). At 12 months, the physical component summary (HRQOL) remained stable in glioma patients, while scores improved in non-CNS cancer controls (pâ=â0.035, dâ=â0.883). In this underpowered study, no evidence for the effectiveness of online guided self-help for depression or HRQOL in glioma patients was found, but it may improve fatigue
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