3,452 research outputs found
Testing the Mean Matrix in High-Dimensional Transposable Data
The structural information in high-dimensional transposable data allows us to
write the data recorded for each subject in a matrix such that both the rows
and the columns correspond to variables of interest. One important problem is
to test the null hypothesis that the mean matrix has a particular structure
without ignoring the potential dependence structure among and/or between the
row and column variables. To address this, we develop a simple and
computationally efficient nonparametric testing procedure to assess the
hypothesis that, in each predefined subset of columns (rows), the column (row)
mean vector remains constant. In simulation studies, the proposed testing
procedure seems to have good performance and unlike traditional approaches, it
is powerful without leading to inflated nominal sizes. Finally, we illustrate
the use of the proposed methodology via two empirical examples from gene
expression microarrays.Comment: in Biometrics, 201
Restored vision in a young dog following corticosteroid treatment of presumptive hypophysitis
Background: Hypophysitis is an umbrella term for a group of disorders involving inflammation of the pituitary
gland. A rare occurrence in humans, hypophysitis can produce a range of clinical signs including (but not limited
to) visual deficits and diabetes insipidus. Only five cases of canine hypophysitis exist in the literature, all presenting
in mature dogs with no visual deficits and a grave outcome. This case report describes the clinical and advanced
imaging features of blindness-inducing presumptive hypophysitis in a dog, which rapidly resolved with medical
management.
Case presentation: A 1-year-and-seven-month-old neutered male Standard Poodle presented with subacute
blindness, ataxia, and polyuria/polydipsia (PUPD). Magnetic resonance imaging (MRI) detected a contrast-enhancing
pituitary mass with perilesional oedema compromising the optic chiasm. Suspecting neoplasia, anti-inflammatory
corticosteroid was commenced prior to radiation therapy planning. Complete resolution of neurological and visual
deficits occurred within 12 days of starting steroid treatment. Repeated advanced imaging indicated macroscopic
resolution of the lesion. An extended thyroid panel with insulin-like growth factor-1 analysis supported a diagnosis
of hypophysitis. Resolution of PUPD was achieved with tapering courses of prednisolone and desmopressin; the
dog has since been clinically normal for 14 months and treatment-free for 11 months.
Conclusions: To the authors’ knowledge, this is the first instance in which a canine pituitary mass has demonstrated
long-term resolution with palliative medical treatment alone, alongside reversal of associated blindness and presumptive
diabetes insipidus. We suspect this lesion to be a form of hypophysitis, which should be included among differential
diagnoses for pituitary masses, and for subacute blindness in dogs. Where possible, we advocate biopsy-confirmation of
hypophysitis prior to timely intervention with anti-inflammatory treatment
Role of interface coupling inhomogeneity in domain evolution in exchange bias
Models of exchange-bias in thin films have been able to describe various
aspects of this technologically relevant effect. Through appropriate choices of
free parameters the modelled hysteresis loops adequately match experiment, and
typical domain structures can be simulated. However, the use of these
parameters, notably the coupling strength between the systems' ferromagnetic
(F) and antiferromagnetic (AF) layers, obscures conclusions about their
influence on the magnetization reversal processes. Here we develop a 2D
phase-field model of the magnetization process in exchange-biased CoO/(Co/Pt)xn
that incorporates the 10 nm-resolved measured local biasing characteristics of
the antiferromagnet. Just three interrelated parameters set to measured
physical quantities of the ferromagnet and the measured density of
uncompensated spins thus suffice to match the experiment in microscopic and
macroscopic detail. We use the model to study changes in bias and coercivity
caused by different distributions of pinned uncompensated spins of the
antiferromagnet, in application-relevant situations where domain wall motion
dominates the ferromagnetic reversal. We show the excess coercivity can arise
solely from inhomogeneity in the density of biasing- and anti-biasing pinned
uncompensated spins in the antiferromagnet. Counter to conventional wisdom,
irreversible processes in the latter are not essential
Botulinum toxin therapy: functional silencing of salivary disorders.
Botulinum toxin (BTX) is a neurotoxic protein produced by Clostridium botulinum, an anaerobic bacterium. BTX therapy is a safe and
effective treatment when used for functional silencing of the salivary glands in disorders such as sialoceles and salivary fistulas that may
have a post-traumatic or post-operative origin. BTX injections can be considered in sialoceles and salivary fistulas after the failure of or
together with conservative treatments (e.g. antibiotics, pressure dressings, or serial aspirations). BTX treatment has a promising role in
chronic sialadenitis. BTX therapy is highly successful in the treatment of gustatory sweating (Frey\u2019s syndrome), and could be considered
the gold standard treatment for this neurological disorder
catena-Poly[[(3,5-dicarboxypyrazine-2,6-dicarboxylato-κ3 O 2,N 1,O 6)lithium(I)]-μ-aqua-[triaqualithium(I)]-μ-aqua]
The title coordination polymer, [Li2(C8H2N2O8)(H2O)5]n contains two symmetry-independent Li+ ions; one is coordinated by five water O atoms, the other by an O,N,O′-tridentate doubly deprotonated pyrazine-2,3,5,6-tetracarboxylate ligand and two water O atoms. Water molecules bridge adjacent Li+ ions into ribbons propagating in [100]; an alternative analysis of the structure considers it to contain alternating [Li(C8H2N2O8)(H2O)2]− anions and [Li(H2O)3]+ cations. In the polymeric model, both lithium ions show distorted trigonal–bipyramidal coordination geometries. Within the ligand, the carboxyl H atoms participate in short, almost symmetric O⋯H⋯O hydrogen bonds in which the non-coordinated carboxylate O atoms are donors and acceptors. In the crystal, the ribbons interact via a network of O—H⋯O hydrogen bonds in which the coordinated water molecules act as donors and ligand carboxylate O atoms as acceptors
Halbach arrays at the nanoscale from chiral spin textures
Mallinson's idea that some spin textures in planar magnetic structures could
produce an enhancement of the magnetic flux on one side of the plane at the
expense of the other gave rise to permanent magnet configurations known as
Halbach magnet arrays. Applications range from wiggler magnets in particle
accelerators and free electron lasers, to motors, to magnetic levitation
trains, but exploiting Halbach arrays in micro- or nanoscale spintronics
devices requires solving the problem of fabrication and field metrology below
100 {\mu}m size. In this work we show that a Halbach configuration of moments
can be obtained over areas as small as 1 x 1 {\mu}m^2 in sputtered thin films
with N\'eel-type domain walls of unique domain wall chirality, and we measure
their stray field at a controlled probe-sample distance of 12.0 x 0.5 nm.
Because here chirality is determined by the interfacial Dyzaloshinkii-Moriya
interaction the field attenuation and amplification is an intrinsic property of
this film, allowing for flexibility of design based on an appropriate
definition of magnetic domains. 100 nm-wide skyrmions illustrate the smallest
kind of such structures, for which our measurement of stray magnetic fields and
mapping of the spin structure shows they funnel the field toward one specific
side of the film given by the sign of the Dyzaloshinkii-Moriya interaction
parameter D.Comment: 12 pages, 4 figure
- …