453 research outputs found
On a two variable class of Bernstein-Szego measures
The one variable Bernstein-Szego theory for orthogonal polynomials on the
real line is extended to a class of two variable measures. The polynomials
orthonormal in the total degree ordering and the lexicographical ordering are
constructed and their recurrence coefficients discussed.Comment: minor change
Trace Formulas in Connection with Scattering Theory for Quasi-Periodic Background
We investigate trace formulas for Jacobi operators which are trace class
perturbations of quasi-periodic finite-gap operators using Krein's spectral
shift theory. In particular we establish the conserved quantities for the
solutions of the Toda hierarchy in this class.Comment: 7 page
Fractional Moment Estimates for Random Unitary Operators
We consider unitary analogs of dimensional Anderson models on
defined by the product where is a deterministic
unitary and is a diagonal matrix of i.i.d. random phases. The
operator is an absolutely continuous band matrix which depends on
parameters controlling the size of its off-diagonal elements. We adapt the
method of Aizenman-Molchanov to get exponential estimates on fractional moments
of the matrix elements of , provided the
distribution of phases is absolutely continuous and the parameters correspond
to small off-diagonal elements of . Such estimates imply almost sure
localization for
Study of Thick CZT Detectors for X-ray and Gamma-Ray Astronomy
CdZnTe (CZT) is a wide bandgap II-VI semiconductor developed for the
spectroscopic detection of X-rays and {\gamma}-rays at room temperature. The
Swift Burst Alert Telescope is using an 5240 cm2 array of 2 mm thick CZT
detectors for the detection of 15-150 keV X-rays from Gamma-Ray Bursts. We
report on the systematic tests of thicker (\geq 0.5 cm) CZT detectors with
volumes between 2 cm3 and 4 cm3 which are potential detector choices for a
number of future X-ray telescopes that operate in the 10 keV to a few MeV
energy range. The detectors contacted in our laboratory achieve Full Width Half
Maximum energy resolutions of 2.7 keV (4.5%) at 59 keV, 3 keV (2.5%) at 122 keV
and 4 keV (0.6%) at 662 keV. The 59 keV and 122 keV energy resolutions are
among the world-best results for \geq 0.5 cm thick CZT detectors. We use the
data set to study trends of how the energy resolution depends on the detector
thickness and on the pixel pitch. Unfortunately, we do not find clear trends,
indicating that even for the extremely good energy resolutions reported here,
the achievable energy resolutions are largely determined by the properties of
individual crystals. Somewhat surprisingly, we achieve the reported results
without applying a correction of the anode signals for the depth of the
interaction. Measuring the interaction depths thus does not seem to be a
pre-requisite for achieving sub-1% energy resolutions at 662 keV.Comment: 15 pages, 11 figure
Changing trends of ocular trauma in the time of COVID-19 pandemic
To reduce the spread of the novel coronavirus (2019-nCoV), countries have promoted a range of unprecedented public health responses. These measures aim at reducing the final size of the epidemic as well as its peak in order to decrease the acute pressure on the health-care system [1]. In Italy, the government ordered people to stay home, restricting movements with the exception of work, urgent matters and health reasons. Furthermore, all commercial and productive activities, except those providing essential services, were obligated to remain closed [2].
Ocular trauma represents a serious public health problem and leading cause of visual impairment [3, 4]. The COVID-19 social distancing measures might have a significant impact on the risk of ocular trauma. In this study, we retrospectively reviewed the charts of all patients presenting to an Italian ophthalmological emergency department (the Ophthalmology Unit of the S.Orsola-Malpighi University Hospital in Bologna) to identify all eye injuries. Data were analysed from 10th March 2020 (i.e. the day in which the quarantine measures were applied in our city) to 10th April 2020, and confronted with those of the same period of the previous year (from 10th March 2019 to 10th April 2019).
In the 2019 study period, there were 354 eye injuries (15.6% of all patients presenting to the emergency department). In the 2020 study period, eye injuries decreased to 112 (19.9% of all patients). The characteristics of eye injuries in the two study periods are reported in Table 1. During quarantine, the proportion of children and adolescents with eye injuries decreased (from 14.7% to 8.0%, Fig. 1a), while the proportion of males increased (from 66.7% to 75.0%, Fig. 1b). Regarding the mechanisms of injury, the percentage of falls and sport injuries had the highest decrease (respectively, from 6.5% to 0.9% and from 5.9% to 2.7%), while injuries during home activities and injuries with plants had the highest increase (respectively, from 12.4% to 17.0% and from 8.5% to 10.7%, Fig. 1c). The percentage of minor injuries with low risk of vision loss increased (from 93.2% to 94.6%), while major injuries requiring monitoring decreased (from 6.8% to 5.4%, Fig. 1d).
There was a striking 68.4% decrease in the number of eye injuries seen in our Unit during the last month. Behavioural changes during the quarantine could be associated with lower risk of trauma. The decreases of sport injuries and of injuries in children during school closure seem to support this hypothesis. However, the drop of patients seeking emergency care affected all injuries, including serious ones potentially associated with vision loss. We believe that some patients may intentionally avoid urgent care rather than risking coronavirus exposure at hospitals. Anecdotal reports suggest that this is also happening for life-threatening medical emergencies such as myocardial infarction and stroke [5, 6]. Since ocular trauma is a major cause of vision loss, the importance of not delaying or avoiding treatment should be stressed to all patients to prevent ocular morbidities
Noise spectra of SIU-GaAs pad detectors with guard rings
This paper presents current noise characterization of circular pad Schottky barrier diodes with guard rings. The diodes were fabricated from undopped semi-insulating GaAs, SIU-GaAs, at the University of Glasgow. Current noise spectra were obtained for the detectors for two pad sizes, with reverse bias applied. Three measurements were also made on one of the detectors under forward bias. The noise spectra show an excess noise component, with a low frequency corner at less than 1kHz, and a flat region at higher frequencies. The magnitude of the white noise is approximately half that expected from shot noise theory for the given leakage currents. A fall in the magnitude of the noise was observed at 20kHz which is attributed to the dielectric relaxation time of the material
Tamanho do genoma em coqueiro (Cocos nucifera L.) via citometria de Fluxo.
O objetivo do presente trabalho foi determinar o tamanho do genoma do coqueiro (Cocos nucÃfera L.) via determinação do conteúdo de DNA estimado via citometria de fluxo. Quatorze genótipos de coco, seis do tipo anão e oito do tipo gigante, foram utilizados nesse estudo. Para tal, amostras de folÃolos medindo aproximadamente 0,5 cm2, por genótipo foram maceradas em solução tampão e filtradas para obtenção de uma suspensão dos núcleos. Posteriormente, os núcleos foram coloridos com iodeto de propÃdeo e em seguida foi adicionado RNase em cada amostra. Como padrão interno foi utilizado a cultivar CE-777 de milho (Zea mays L.). Após 30 minutos, as amostras foram analisadas em citômetro de fluxo (Partec PA II); para cada genótipo foi feito a leitura de cinco amostras. O conteúdo 2C de DNA de cada genótipo foi determinado, com médias variando de 2,74 pg a 2,86 pg, sendo a média geral 2,80 pg o que corresponde a 2.744 Mpb. O conteúdo de DNA do grupo Gigante foi o mais varável sendo o maior conteúdo estimado para o Gigante de Rennel, e o menor conteúdo para Gigante do Oeste Africano; o grupo Anão teve uma menor variação. A média do conteúdo 2C de DNA do grupo gigante foi de 2,80 pg e a do grupo Anão foi de 2,78pg. Os coeficientes de variação variaram de 2,5% a 3,1%, o que indica a precisão das medições. O teste Scott e Knott a 5% de probabilidade, agrupou os genótipos em 4 classes de acordo com as médias do conteúdo de DNA. Os resultados permitiram concluir que a espécie apresenta baixo conteúdo de DNA quando comparada com outros membros da famÃlia Arecaceae
Integrated Circuit Design in US High-Energy Physics
This whitepaper summarizes the status, plans, and challenges in the area of
integrated circuit design in the United States for future High Energy Physics
(HEP) experiments. It has been submitted to CPAD (Coordinating Panel for
Advanced Detectors) and the HEP Community Summer Study 2013(Snowmass on the
Mississippi) held in Minnesota July 29 to August 6, 2013. A workshop titled: US
Workshop on IC Design for High Energy Physics, HEPIC2013 was held May 30 to
June 1, 2013 at Lawrence Berkeley National Laboratory (LBNL). A draft of the
whitepaper was distributed to the attendees before the workshop, the content
was discussed at the meeting, and this document is the resulting final product.
The scope of the whitepaper includes the following topics: Needs for IC
technologies to enable future experiments in the three HEP frontiers Energy,
Cosmic and Intensity Frontiers; Challenges in the different technology and
circuit design areas and the related R&D needs; Motivation for using different
fabrication technologies; Outlook of future technologies including 2.5D and 3D;
Survey of ICs used in current experiments and ICs targeted for approved or
proposed experiments; IC design at US institutes and recommendations for
collaboration in the future
Resectable IIIA-N2 non-small-cell lung cancer (NSCLC): In search for the proper treatment
Locally advanced non-small cell lung cancer accounts for one third of non-small cell lung cancer (NSCLC) at the time of initial diagnosis and presents with a wide range of clinical and pathological heterogeneity. To date, the combined multimodality approach involving both local and systemic control is the gold standard for these patients, since occult distant micrometastatic disease should always be suspected. With the rapid increase in treatment options, the need for an interdisciplinary discussion involving oncologists, surgeons, radiation oncologists and radiologists has become essential. Surgery should be recommended to patients with non-bulky, discrete, or single-level N2 involvement and be included in the multimodality treatment. Resectable stage IIIA patients have been the subject of a number of clinical trials and retrospective analysis, discussing the efficiency and survival benefits on patients treated with the available therapeutic approaches. However, most of them have some limitations due to their retrospective nature, lack of exact pretreatment staging, and the involvement of heterogeneous populations leading to the awareness that each patient should undergo a tailored therapy in light of the nature of his tumor, its extension and his performance status
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