697 research outputs found
Monovalent counterion distributions at highly charged water interfaces: Proton-transfer and Poisson-Boltzmann theory
Surface sensitive synchrotron-X-ray scattering studies reveal the
distributions of monovalent ions next to highly charged interfaces. A lipid
phosphate (dihexadecyl hydrogen-phosphate) was spread as a monolayer at the
air-water interface, containing CsI at various concentrations. Using anomalous
reflectivity off and at the Cs resonance, we provide, for the first
time, spatial counterion distributions (Cs) next to the negatively charged
interface over a wide range of ionic concentrations. We argue that at low salt
concentrations and for pure water the enhanced concentration of hydroniums
HO at the interface leads to proton-transfer back to the phosphate
group by a high contact-potential, whereas high salt concentrations lower the
contact-potential resulting in proton-release and increased surface
charge-density. The experimental ionic distributions are in excellent agreement
with a renormalized-surface-charge Poisson-Boltzmann theory without fitting
parameters or additional assumptions
Surface and interface study of pulsed-laser-deposited off-stoichiometric NiMnSb thin films on Si(100) substrate
We report a detailed study of surface and interface properties of
pulsed-laser deposited NiMnSb films on Si (100) substrate as a function of film
thickness. As the thickness of films is reduced below 35 nm formation of a
porous layer is observed. Porosity in this layer increases with decrease in
NiMnSb film thickness. These morphological changes of the ultra thin films are
reflected in the interesting transport and magnetic properties of these films.
On the other hand, there are no influences of compositional in-homogeneity and
surface/interface roughness on the magnetic and transport properties of the
films.Comment: 13 pages, 7 figures, Submitted to Phys. Rev.
Myolipoma Affecting the Erector Spinae: A Case Report in a Child
Myolipoma is a rare, benign, lipomatous tumour which most commonly occurs in the retroperitoneum, pelvis, and abdomen. A 4-year-old boy presented with a painless enlarging mass in the left paraspinal region. Magnetic Resonance Imaging (MRI) revealed a soft tissue lesion with high fat content and areas of calcification. Excision and histopathological analysis revealed a tumour composed of lobules of mature adipose tissue and broad septa of well-differentiated smooth muscle tissue. The smooth muscle nature of the nonfatty component was demonstrated by a diffuse and strong immunoreactivity for smooth muscle actin and desmin. The mass was reported as a myolipoma. The patient made an unremarkable recovery from surgery and remains healthy with no signs of recurrence at seven years. This paper represents the youngest patient diagnosed with this rare soft tissue tumour which is normally confined to the adult population. A newly reported site of the tumour is also highlighted
Binary separation in very thin nematic films: thickness and phase coexistence
The behavior as a function of temperature of very thin films (10 to 200 nm)
of pentylcyanobiphenyl (5CB) on silicon substrates is reported. In the vicinity
of the nematic/isotropic transition we observe a coexistence of two regions of
different thicknesses: thick regions are in the nematic state while thin ones
are in the isotropic state. Moreover, the transition temperature is shifted
downward following a 1/h^2 law (h is the film thickness). Microscope
observations and small angle X-ray scattering allowed us to draw a phase
diagram which is explained in terms of a binary first order phase transition
where thickness plays the role of an order parameter.Comment: 5 pages, 3 figures, submitted to PRL on the 26th of Apri
Post-traumatic stress disorder following childbirth: an update of current issues and recommendations for future research
Objective:
This paper aimed to report the current status of research in the field of post-traumatic stress disorder following childbirth (PTSD FC), and to update the findings of an earlier 2008 paper.
Background:
A group of international researchers, clinicians and service users met in 2006 to establish the state of clinical and academic knowledge relating to PTSD FC. A paper identified four key areas of research knowledge at that time.
Methods:
Fourteen clinicians and researchers met in Oxford, UK to update the previously published paper relating to PTSD FC. The first part of the meeting focused on updating the four key areas identified previously, and the second part on discussing new and emerging areas of research within the field.
Results:
A number of advances have been made in research within the area of PTSD FC. Prevalence is well established within mothers, several intervention studies have been published, and there is growing interest in new areas: staff and pathways; prevention and early intervention; impact on families and children; special populations; and post-traumatic growth.
Conclusion:
Despite progress, significant gaps remain within the PTSD FC knowledge base. Further research continues to be needed across all areas identified in 2006, and five areas were identified which can be seen as ânew and emergingâ. All of these new areas require further extensive research. Relatively little is still known about PTSD FC
Clinical course, therapeutic responses and outcomes in relapsing MOG antibody-associated demyelination.
Abstract
OBJECTIVE:
We characterised the clinical course, treatment and outcomes in 59 patients with relapsing myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination.
METHODS:
We evaluated clinical phenotypes, annualised relapse rates (ARR) prior and on immunotherapy and Expanded Disability Status Scale (EDSS), in 218 demyelinating episodes from 33 paediatric and 26 adult patients.
RESULTS:
The most common initial presentation in the cohort was optic neuritis (ON) in 54% (bilateral (BON) 32%, unilateral (UON) 22%), followed by acute disseminated encephalomyelitis (ADEM) (20%), which occurred exclusively in children. ON was the dominant phenotype (UON 35%, BON 19%) of all clinical episodes. 109/226 (48%) MRIs had no brain lesions. Patients were steroid responsive, but 70% of episodes treated with oral prednisone relapsed, particularly at doses <10\u2009mg daily or within 2 months of cessation. Immunotherapy, including maintenance prednisone (P=0.0004), intravenous immunoglobulin, rituximab and mycophenolate, all reduced median ARRs on-treatment. Treatment failure rates were lower in patients on maintenance steroids (5%) compared with non-steroidal maintenance immunotherapy (38%) (P=0.016). 58% of patients experienced residual disability (average follow-up 61 months, visual loss in 24%). Patients with ON were less likely to have sustained disability defined by a final EDSS of 652 (OR 0.15, P=0.032), while those who had any myelitis were more likely to have sustained residual deficits (OR 3.56, P=0.077).
CONCLUSION:
Relapsing MOG antibody-associated demyelination is strongly associated with ON across all age groups and ADEM in children. Patients are highly responsive to steroids, but vulnerable to relapse on steroid reduction and cessation
X-ray standing wave and reflectometric characterization of multilayer structures
Microstructural characterization of synthetic periodic multilayers by x-ray
standing waves have been presented. It has been shown that the analysis of
multilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW)
techniques can overcome the deficiencies of the individual techniques in
microstructural analysis. While interface roughnesses are more accurately
determined by the XRR technique, layer composition is more accurately
determined by the XSW technique where an element is directly identified by its
characteristic emission. These aspects have been explained with an example of a
20 period Pt/C multilayer. The composition of the C-layers due to Pt
dissolution in the C-layers, PtC, has been determined by the XSW
technique. In the XSW analysis when the whole amount of Pt present in the
C-layers is assumed to be within the broadened interface, it l eads to larger
interface roughness values, inconsistent with those determined by the XRR
technique. Constraining the interface roughness values to those determined by
the XRR technique, requires an additional amount of dissolved Pt in the
C-layers to expl ain the Pt fluorescence yield excited by the standing wave
field. This analysis provides the average composition PtC of the
C-layers .Comment: 12 pages RevTex, 10 eps figures embedde
Determination of total x-ray absorption coefficient using non-resonant x-ray emission
An alternative measure of x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has recently been developed that is both bulk sensitive and free of saturation effects. Here we show that the angle dependence of IPFY can provide a measure directly proportional to the total x-ray absorption coefficient, ”(E). In contrast, fluorescence yield (FY) and electron yield (EY) spectra are offset and/or distorted from ”(E) by an unknown and difficult to measure amount. Moreover, our measurement can determine ”(E) in absolute units with no free parameters by scaling to ”(E) at the non-resonant emission energy. We demonstrate this technique with measurements on NiO and NdGaO3. Determining ”(E) across edge-steps enables the use of XAS as a non-destructive measure of material composition. In NdGaO3, we also demonstrate the utility of IPFY for insulating samples, where neither EY or FY provide reliable spectra due to sample charging and self-absorption effects, respectively
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