460 research outputs found
Fundamental Limits of "Ankylography" due to Dimensional Deficiency
Single-shot diffractive imaging of truly 3D structures suffers from a
dimensional deficiency and does not scale. The applicability of "ankylography"
is limited to objects that are small-sized in at least one dimension or that
are essentially 2D otherwise.Comment: 2 pages, no figur
Slepian functions and their use in signal estimation and spectral analysis
It is a well-known fact that mathematical functions that are timelimited (or
spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the
finite precision of measurement and computation unavoidably bandlimits our
observation and modeling scientific data, and we often only have access to, or
are only interested in, a study area that is temporally or spatially bounded.
In the geosciences we may be interested in spectrally modeling a time series
defined only on a certain interval, or we may want to characterize a specific
geographical area observed using an effectively bandlimited measurement device.
It is clear that analyzing and representing scientific data of this kind will
be facilitated if a basis of functions can be found that are "spatiospectrally"
concentrated, i.e. "localized" in both domains at the same time. Here, we give
a theoretical overview of one particular approach to this "concentration"
problem, as originally proposed for time series by Slepian and coworkers, in
the 1960s. We show how this framework leads to practical algorithms and
statistically performant methods for the analysis of signals and their power
spectra in one and two dimensions, and on the surface of a sphere.Comment: Submitted to the Handbook of Geomathematics, edited by Willi Freeden,
Zuhair M. Nashed and Thomas Sonar, and to be published by Springer Verla
Scalar and vector Slepian functions, spherical signal estimation and spectral analysis
It is a well-known fact that mathematical functions that are timelimited (or
spacelimited) cannot be simultaneously bandlimited (in frequency). Yet the
finite precision of measurement and computation unavoidably bandlimits our
observation and modeling scientific data, and we often only have access to, or
are only interested in, a study area that is temporally or spatially bounded.
In the geosciences we may be interested in spectrally modeling a time series
defined only on a certain interval, or we may want to characterize a specific
geographical area observed using an effectively bandlimited measurement device.
It is clear that analyzing and representing scientific data of this kind will
be facilitated if a basis of functions can be found that are "spatiospectrally"
concentrated, i.e. "localized" in both domains at the same time. Here, we give
a theoretical overview of one particular approach to this "concentration"
problem, as originally proposed for time series by Slepian and coworkers, in
the 1960s. We show how this framework leads to practical algorithms and
statistically performant methods for the analysis of signals and their power
spectra in one and two dimensions, and, particularly for applications in the
geosciences, for scalar and vectorial signals defined on the surface of a unit
sphere.Comment: Submitted to the 2nd Edition of the Handbook of Geomathematics,
edited by Willi Freeden, Zuhair M. Nashed and Thomas Sonar, and to be
published by Springer Verlag. This is a slightly modified but expanded
version of the paper arxiv:0909.5368 that appeared in the 1st Edition of the
Handbook, when it was called: Slepian functions and their use in signal
estimation and spectral analysi
From Luttinger to Fermi liquids in organic conductors
This chapter reviews the effects of interactions in quasi-one dimensional
systems, such as the Bechgaard and Fabre salts, and in particular the Luttinger
liquid physics. It discusses in details how transport measurements both d.c.
and a.c. allow to probe such a physics. It also examine the dimensional
crossover and deconfinement transition occurring between the one dimensional
case and the higher dimensional one resulting from the hopping of electrons
between chains in the quasi-one dimensional structure.Comment: To be published In the book "The Physics of Organic Conductors and
Superconductors", Springer, 2007, ed. A. Lebe
A randomized phase 3 study of ixazomib–dexamethasone versus physician’s choice in relapsed or refractory AL amyloidosis
In the first phase 3 study in relapsed/refractory AL amyloidosis (TOURMALINE-AL1 NCT01659658), 168 patients with relapsed/refractory AL amyloidosis after 1–2 prior lines were randomized to ixazomib (4 mg, days 1, 8, 15) plus dexamethasone (20 mg, days 1, 8, 15, 22; n = 85) or physician’s choice (dexamethasone ± melphalan, cyclophosphamide, thalidomide, or lenalidomide; n = 83) in 28-day cycles until progression or toxicity. Primary endpoints were hematologic response rate and 2-year vital organ deterioration or mortality rate. Only the first primary endpoint was formally tested at this interim analysis. Best hematologic response rate was 53% with ixazomib–dexamethasone vs 51% with physician’s choice (p = 0.76). Complete response rate was 26 vs 18% (p = 0.22). Median time to vital organ deterioration or mortality was 34.8 vs 26.1 months (hazard ratio 0.53; 95% CI, 0.32–0.87; p = 0.01). Median treatment duration was 11.7 vs 5.0 months. Adverse events of clinical importance included diarrhea (34 vs 30%), rash (33 vs 20%), cardiac arrhythmias (26 vs 15%), nausea (24 vs 14%). Despite not meeting the first primary endpoint, all time-to-event data favored ixazomib–dexamethasone. These results are clinically relevant to this relapsed/refractory patient population with no approved treatment options
Wall roughness induces asymptotic ultimate turbulence
Turbulence is omnipresent in Nature and technology, governing the transport
of heat, mass, and momentum on multiple scales. For real-world applications of
wall-bounded turbulence, the underlying surfaces are virtually always rough;
yet characterizing and understanding the effects of wall roughness for
turbulence remains a challenge, especially for rotating and thermally driven
turbulence. By combining extensive experiments and numerical simulations, here,
taking as example the paradigmatic Taylor-Couette system (the closed flow
between two independently rotating coaxial cylinders), we show how wall
roughness greatly enhances the overall transport properties and the
corresponding scaling exponents. If only one of the walls is rough, we reveal
that the bulk velocity is slaved to the rough side, due to the much stronger
coupling to that wall by the detaching flow structures. If both walls are
rough, the viscosity dependence is thoroughly eliminated in the boundary layers
and we thus achieve asymptotic ultimate turbulence, i.e. the upper limit of
transport, whose existence had been predicted by Robert Kraichnan in 1962
(Phys. Fluids {\bf 5}, 1374 (1962)) and in which the scalings laws can be
extrapolated to arbitrarily large Reynolds numbers
Genetic contributions to visuospatial cognition in Williams syndrome: insights from two contrasting partial deletion patients
Background
Williams syndrome (WS) is a rare neurodevelopmental disorder arising from a hemizygotic deletion of approximately 27 genes on chromosome 7, at locus 7q11.23. WS is characterised by an uneven cognitive profile, with serious deficits in visuospatial tasks in comparison to relatively proficient performance in some other cognitive domains such as language and face processing. Individuals with partial genetic deletions within the WS critical region (WSCR) have provided insights into the contribution of specific genes to this complex phenotype. However, the combinatorial effects of different genes remain elusive.
Methods
We report on visuospatial cognition in two individuals with contrasting partial deletions in the WSCR: one female (HR), aged 11 years 9 months, with haploinsufficiency for 24 of the WS genes (up to GTF2IRD1), and one male (JB), aged 14 years 2 months, with the three most telomeric genes within the WSCR deleted, or partially deleted.
Results
Our in-depth phenotyping of the visuospatial domain from table-top psychometric, and small- and large-scale experimental tasks reveal a profile in HR in line with typically developing controls, albeit with some atypical features. These data are contrasted with patient JB’s atypical profile of strengths and weaknesses across the visuospatial domain, as well as with more substantial visuospatial deficits in individuals with the full WS deletion.
Conclusions
Our findings point to the contribution of specific genes to spatial processing difficulties associated with WS, highlighting the multifaceted nature of spatial cognition and the divergent effects of genetic deletions within the WSCR on different components of visuospatial ability. The importance of general transcription factors at the telomeric end of the WSCR, and their combinatorial effects on the WS visuospatial phenotype are also discussed
Birtamimab plus standard of care in light-chain amyloidosis: the phase 3 randomized placebo-controlled VITAL trial
Amyloid light-chain (AL) amyloidosis is a rare, typically fatal disease characterized by the accumulation of misfolded immunoglobulin light chains (LCs). Birtamimab is an investigational humanized monoclonal antibody designed to neutralize toxic LC aggregates and deplete insoluble organ-deposited amyloid via macrophage-induced phagocytosis. VITAL was a phase 3 randomized, double-blind, placebo-controlled clinical trial assessing the efficacy and safety of birtamimab + standard of care (SOC) in 260 newly diagnosed, treatment-naive patients with AL amyloidosis. Patients received 24 mg/kg IV birtamimab + SOC or placebo + SOC every 28 days. The primary composite end point was the time to all-cause mortality (ACM) or centrally adjudicated cardiac hospitalization ≥91 days after the first study drug infusion. The trial was terminated early after an interim futility analysis; there was no significant difference in the primary composite end point (hazard ratio [HR], 0.826; 95% confidence interval [CI], 0.574-1.189; log-rank P = .303). A post hoc analysis of patients with Mayo stage IV AL amyloidosis, those at the highest risk of early mortality, showed significant improvement in the time to ACM with birtamimab at month 9 (HR, 0.413; 95% CI, 0.191-0.895; log-rank P = .021). At month 9, 74% of patients with Mayo stage IV AL amyloidosis treated with birtamimab and 49% of those given placebo survived. Overall, the rates of treatment-emergent adverse events (TEAEs) and serious TEAEs were generally similar between treatment arms. A confirmatory phase 3 randomized, double-blind, placebo-controlled clinical trial of birtamimab in patients with Mayo stage IV AL amyloidosis (AFFIRM-AL; NCT04973137) is currently enrolling. The VITAL trial was registered at www.clinicaltrials.gov as #NCT02312206
Further investigation of confirmed urinary tract infection (UTI) in children under five years: a systematic review.
Background: Further investigation of confirmed UTI in children aims to prevent renal scarring and future complications. Methods: We conducted a systematic review to determine the most effective approach to the further investigation of confirmed urinary tract infection (UTI) in children under five years of age. Results: 73 studies were included. Many studies had methodological limitations or were poorly reported. Effectiveness of further investigations: One study found that routine imaging did not lead to a reduction in recurrent UTIs or renal scarring. Diagnostic accuracy: The studies do not support the use of less invasive tests such as ultrasound as an alternative to renal scintigraphy, either to rule out infection of the upper urinary tract (LR- = 0.57, 95%CI: 0.47, 0.68) and thus to exclude patients from further investigation or to detect renal scarring (LR+ = 3.5, 95% CI: 2.5, 4.8). None of the tests investigated can accurately predict the development of renal scarring. The available evidence supports the consideration of contrast-enhanced ultrasound techniques for detecting vesico-ureteric reflux (VUR), as an alternative to micturating cystourethrography (MCUG) (LR+ = 14.1, 95% CI: 9.5, 20.8; LR- = 0.20, 95%CI: 0.13, 0.29); these techniques have the advantage of not requiring exposure to ionising radiation. Conclusion: There is no evidence to support the clinical effectiveness of routine investigation of children with confirmed UTI. Primary research on the effectiveness, in terms of improved patient outcome, of testing at all stages in the investigation of confirmed urinary tract infection is urgently required
Kaposi's sarcoma of the hand mimicking squamous cell carcinoma in a woman with no evidence of HIV infection: a case report
<p>Abstract</p> <p>Introduction</p> <p>Kaposi's sarcoma is a vascular neoplasm mainly affecting the skin of the lower extremities. Although it is the most common neoplasm affecting patients with AIDS, sporadic cases in HIV-negative people have been reported. It is a lesion mainly affecting men and its clinical presentation presents a challenge, as it can resemble other benign or malignant skin lesions.</p> <p>Case presentation</p> <p>We report a rare case of Kaposi's sarcoma presenting in a 68-year-old Mediterranean woman with no evidence of HIV infection. The patient had a 6-month history of a slowly progressing pigmented lesion on the dorsum of her left hand. The lesion clinically resembled a squamous cell carcinoma. The patient was treated with a wide excision of the lesion and primary reconstruction with a full thickness skin graft. Histopathological and immunohistochemical analysis of the excised lesion revealed the presence of Kaposi's sarcoma. Serologic investigation for HIV was negative but polymerase chain reaction for human herpes virus type 8 infection was positive. Thorough clinical and imaging investigation of the abdomen and chest were both negative for loci of disease.</p> <p>Conclusion</p> <p>Kaposi's sarcoma, although rare in its sporadic form, should be considered in the differential diagnosis of indeterminate skin lesions, especially those affecting the extremities.</p
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