6,552 research outputs found
Theory of STM Spectroscopy of Kondo Ions on Metal Surfaces
The conduction electron density of states nearby a single magnetic impurity,
as measured recently by scanning tunneling microscopy (STM), is calculated. It
is shown that the Kondo effect induces a narrow Fano resonance as an intrinsic
feature in the conduction electron density of states. The line shape varies
with the distance between STM tip and impurity, in qualitative agreement with
experiments, and is sensitive to details of the band structure. For a Co
impurity the experimentally observed width and shift of the Kondo resonance are
in accordance with those obtained from a combination of band structure and
strongly correlated calculations.Comment: 5 pages, 4 figures, presented at the NATO Advanced Research Workshop
on "Size Dependent Magnetic Scattering", Pecs, Hungary, May 28 - June 1, 200
Blink rate measured in situ decreases while reading from printed text or digital devices, regardless of task duration, difficulty or viewing distance
Purpose: To compare blinking measured in situ during various tasks and examine relationships with ocular surface symptoms. The day-to-day repeatability of the blink rate and interblink interval was assessed
Ligand-based virtual screening using binary kernel discrimination
This paper discusses the use of a machine-learning technique called binary kernel discrimination (BKD) for virtual screening in drug- and pesticide-discovery programmes. BKD is compared with several other ligand-based tools for virtual screening in databases of 2D structures represented by fragment bit-strings, and is shown to provide an effective, and reasonably efficient, way of prioritising compounds for biological screening
Providing patients with direct access to musculoskeletal physiotherapy: the impact on general practice musculoskeletal workload and resource use. The STEMS-2 study.
OBJECTIVES: This study examined the real-world impact of patient direct access to NHS physiotherapy (self-referral) on (a) general practice consultations for musculoskeletal (MSK) conditions and (b) specified clinical management for patients with MSK conditions.
DESIGN AND SETTING: Natural experiment in four general practices and the associated physiotherapy service.
METHODS: Anonymised routinely collected data were obtained. MSK coded GP consultations, recorded fit notes, MSK-related prescription medication, X-rays and MRI requests, and referrals to secondary care for patients consulting with MSK conditions were identified and trends described across a 6-year period (June 2011 to June 2017). Joinpoint regression analysis was used to identify any significant changes in GP MSK consultation trends before and after the introduction of self-referral to physiotherapy. Physiotherapy service data examined access methods used by patients (GP referred, GP recommended self-referral, true self-referral) and the number of physiotherapy sessions.
RESULTS: Direct access resulted in inconsistent impact on general practices. In one arm of the experiment a significant increase in GP consultations was observed and in one arm was stable. Exploratory examination of clinical management showed only requests for X-rays (arm 1) and possibly requests for MRI (arm 2) changed over time. Physiotherapy service referrals showed a low uptake of true self-referral (10% and 6%) in each arm respectively.
CONCLUSION: This is the first study to examine the real-world impact of patient direct access to physiotherapy at general practice level. We found no consistent impact of patient direct access on GP MSK workload. Impact on some clinical management was observed but not consistently in the direction suggested by previous studies
The rest-frame ultraviolet spectra of GRBs from massive rapidly-rotating stellar progenitors
The properties of a massive star prior to its final explosion are imprinted
in the circumstellar medium (CSM) created by its wind and termination shock. We
perform a detailed, comprehensive calculation of the time-variable and
angle-dependent transmission spectra of an average-luminosity Gamma-Ray Burst
(GRB) which explodes in the CSM structure produced by the collapse of a 20
Msun, rapidly rotating, Z=0.001 progenitor star. We study both the case in
which metals are initially in the gaseous phase, as well as the situation in
which they are heavily depleted into dust. We find that high-velocity lines
from low-ionization states of silicon, carbon, and iron are initially present
in the spectrum only if the metals are heavily depleted into dust prior to the
GRB explosion. However, such lines disappear on timescales of a fraction of a
second for a burst observed on-axis, and of a few seconds for a burst seen at
high-latitude, making their observation virtually impossible. Rest-frame lines
produced in the termination shock are instead clearly visible in all
conditions. We conclude that time-resolved, early-time spectroscopy is not a
promising way in which the properties of the GRB progenitor wind can be
routinely studied. Previous detections of high velocity features in GRB UV
spectra must have been due either due to a superposition of a physically
unrelated absorber or to a progenitor star with very unusual properties.Comment: Published in MNRAS; higher resolution figures in published version
Dialkyldithiophosphate Acids (HDDPs) as Effective Lubricants of Sol–Gel Titania Coatings in Technical Dry Friction Conditions
The goal of this study was the investigation of
the effectiveness of dialkyldithiophosphate acids (HDDPs)
films in improving the tribological properties of thin, sol–
gel derived titania coatings. Amorphous, anatase, and rutile
titania coatings were obtained using sol–gel dip–coating
deposition after treatment at 100, 500, and 1,000 C,
respectively. Titania coatings were then modified from the
liquid phase by HDDPs acids having dodecyl-(C12), tetradecyl-(C14),
and hexadecyl-(C16) alkyl chains deposited by
dip–coating (DC) and Langmuir–Blodgett (LB) methods.
The influence of the deposition procedure, the length of the
HDDPs alkyl chain and the type of titania substrate on the
surface morphology and tribological properties were studied.
It was found, using wetting contact angle measurements,
that these modifications of titania coatings decrease
the surface free energy and increase its hydrophobicity.
The surface topography imaged by Atomic force microscopy
(AFM), exhibit island-like or agglomerate features for
the DC deposition method, while smooth topographies
were observed for LB depositions. Tribological tests were
conducted by means of a microtribometer operating in the
normal load range 30–100 mN. An enhancement of tribological
properties was observed upon modification, as
compared to unmodified titania
GRB 090426: The Environment of a Rest-Frame 0.35-second Gamma-Ray Burst at Redshift z=2.609
We present the discovery of an absorption-line redshift of z = 2.609 for GRB
090426, establishing the first firm lower limit to a redshift for a gamma-ray
burst with an observed duration of <2 s. With a rest-frame burst duration of
T_90z = 0.35 s and a detailed examination of the peak energy of the event, we
suggest that this is likely (at >90% confidence) a member of the short/hard
phenomenological class of GRBs. From analysis of the optical-afterglow spectrum
we find that the burst originated along a very low HI column density sightline,
with N_HI < 3.2 x 10^19 cm^-2. Our GRB 090426 afterglow spectrum also appears
to have weaker low-ionisation absorption (Si II, C II) than ~95% of previous
afterglow spectra. Finally, we also report the discovery of a blue, very
luminous, star-forming putative host galaxy (~2 L*) at a small angular offset
from the location of the optical afterglow. We consider the implications of
this unique GRB in the context of burst duration classification and our
understanding of GRB progenitor scenarios.Comment: Submitted to MNRA
Secreted Endothelial Cell Factors Immobilized on Collagen Scaffolds Enhance the Recipient Endothelial Cell Environment
Strategies to design novel vascular scaffolds are a continuing aim in tissue engineering and often such designs encompass the use of recombinant factors to enhance the performance of the scaffold. The established use of cell secretion utilized in feeder systems and conditioned media offer a source of paracrine factors, which has potential to be used in tissue-engineered (TE) scaffolds. Here we utilize this principle from endothelial cells (ECs), to create a novel TE scaffold by harnessing secreted factors and immobilizing these to collagen scaffolds. This research revealed increased cellular attachment and positive angiogenic gene upregulation responses in recipient ECs grown on these conditioned scaffolds. Also, the conditioning method did not affect the mechanical structural integrity of the scaffolds. These results may advocate the potential use of this system to improve vascular scaffolds' in vivo performance. In addition, this process may be a future method utilized to improve other tissue engineering scaffold therapies
Visceral hyperalgesia induced by forebrain-specific suppression of native Kv7/KCNQ/M-current in mice
<p>Abstract</p> <p>Background</p> <p>Dysfunction of brain-gut interaction is thought to underlie visceral hypersensitivity which causes unexplained abdominal pain syndromes. However, the mechanism by which alteration of brain function in the brain-gut axis influences the perception of visceral pain remains largely elusive. In this study we investigated whether altered brain activity can generate visceral hyperalgesia.</p> <p>Results</p> <p>Using a forebrain specific αCaMKII promoter, we established a line of transgenic (Tg) mice expressing a dominant-negative pore mutant of the Kv7.2/KCNQ2 channel which suppresses native KCNQ/M-current and enhances forebrain neuronal excitability. Brain slice recording of hippocampal pyramidal neurons from these Tg mice confirmed the presence of hyperexcitable properties with increased firing. Behavioral evaluation of Tg mice exhibited increased sensitivity to visceral pain induced by intraperitoneal (i.p.) injection of either acetic acid or magnesium sulfate, and intracolon capsaicin stimulation, but not cutaneous sensation for thermal or inflammatory pain. Immunohistological staining showed increased c-Fos expression in the somatosensory SII cortex and insular cortex of Tg mice that were injected intraperitoneally with acetic acid. To mimic the effect of cortical hyperexcitability on visceral hyperalgesia, we injected KCNQ/M channel blocker XE991 into the lateral ventricle of wild type (WT) mice. Intracerebroventricular injection of XE991 resulted in increased writhes of WT mice induced by acetic acid, and this effect was reversed by co-injection of the channel opener retigabine.</p> <p>Conclusions</p> <p>Our findings provide evidence that forebrain hyperexcitability confers visceral hyperalgesia, and suppression of central hyperexcitability by activation of KCNQ/M-channel function may provide a therapeutic potential for treatment of abdominal pain syndromes.</p
What's new in the management of chronic lymphocytic leukemia? 2008 ASH Review (New York Medical College, January 31, 2009)
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