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1.
Eur Rev Med Pharmacol Sci ; 26(16): 5844-5856, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-36066160

RESUMO

OBJECTIVE: Mycoplasma pneumoniae (M. pneumoniae) pneumonia is the second-most common cause of community-acquired pneumonia (CAP). This study aimed at investigating into the prevalence of macrolide-resistant M. pneumoniae (MRMP) with respiratory virus co-infection and the antibiotic prescriptions in children with CAP in four provinces in Korea, and to assess the variations in the findings across regions and throughout the year. PATIENTS AND METHODS: This prospective study was conducted in 29 hospitals in Korea between July 2018 and June 2020. Among the enrolled 1,063 children with CAP, all 451 patients with M. pneumoniae underwent PCR assays of M. pneumoniae and respiratory viruses, and the presence of point mutations of residues 2063 and 2064 was evaluated. RESULTS: Gwangju-Honam (88.6%) showed the highest prevalence of MRMP pneumonia, while Daejeon-Chungcheong (71.3%) showed the lowest, although the differences in prevalence were not significant (p=0.074). Co-infection of M. pneumoniae pneumonia and respiratory virus was observed in 206 patients (45.4%), and rhinovirus co-infection (101 children; 22.2%) was the most frequent. The prevalence of MRMP pneumonia with respiratory virus co-infection and the antibiotic prescriptions differed significantly among the four provinces (p < 0.05). The monthly rate of MRMP pneumonia cases among all cases of M. pneumoniae pneumonia and tetracycline or quinolone prescriptions did not differ significantly among the four regions (trend p > 0.05) during the study period. CONCLUSIONS: The prevalence of M. pneumoniae pneumonia with virus co-infection and antibiotic prescriptions could differ according to region, although the MRMP pneumonia rate showed no difference within Korea.


Assuntos
Coinfecção , Infecções Comunitárias Adquiridas , Pneumonia por Mycoplasma , Viroses , Vírus , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Criança , Coinfecção/complicações , Coinfecção/tratamento farmacológico , Coinfecção/epidemiologia , Farmacorresistência Bacteriana , Humanos , Macrolídeos/uso terapêutico , Mycoplasma pneumoniae/genética , Pneumonia por Mycoplasma/tratamento farmacológico , Pneumonia por Mycoplasma/epidemiologia , Prescrições , Estudos Prospectivos , Viroses/tratamento farmacológico
2.
J Phys Condens Matter ; 30(23): 235701, 2018 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-29714172

RESUMO

The complex dielectric function ([Formula: see text]) of WSe2 monolayer grown by atomic layer deposition is investigated using spectroscopic ellipsometry. Band structure parameters are obtained by standard line-shape analysis of the second-energy-derivative of [Formula: see text] spectra. The fundamental band gap is observed at 2.26 eV, corresponds to transition between valence band (VB) maximum at the K point and conduction band (CB) minimum at Q point in the Brillouin zone (BZ). Two strong so-called A and B excitonic peaks in [Formula: see text] spectra originate from vertical transitions from spin-orbit split (0.43 eV) VB to CB at K point of the BZ. Binding energies of A and B exactions are 0.71 and 0.28 eV, respectively. Well resolved five excited excitons states has been detected within the spectral region between A and B. Energy profile of the Rydberg series shows significant deviation from the hydrogenic behavior, discussed in connection with the 2D hydrogen model. Results presented here will improve our understanding about the optical response of 2D materials and will help to design better optoelectronic applications and validate theoretical considerations.

3.
Phys Med Biol ; 62(11): 4589-4603, 2017 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-28440226

RESUMO

The aim of this study is to investigate the feasibility of water and lipid as calibration phantoms for accurate dual energy breast density quantification. Dual energy calibration was performed on a mammography system based on scanning multi-slit Si strip photon-counting detectors using plastic water and adipose-equivalent phantoms as the basis materials. Two different methods were used to convert the dual energy decomposition measurements in plastic phantom thicknesses into the true water and lipid basis materials. The first method was based entirely on the theoretically calculated effective attenuation coefficients of the investigated materials in the mammographic energy range. The conversion matrix was determined through the linear least-squares fitting of the target material using the calculated effective attenuation coefficients of water and lipid. The second method was based on experimental calibration with plastic water phantom, adipose-equivalent phantom, and its correlation to known water and lipid thicknesses. These two methods were then validated by using an independent measurement of water and lipid mixture phantoms and postmortem breasts. The correlation between the dual energy decomposition measurements and the known values was evaluated using linear regression analysis. The averaged root-mean-square errors for water density quantification derived from the theoretical and experimental conversions were 8.6% and 1.6%, respectively. The postmortem breast tissue study also indicates that the experimentally acquired conversion coefficient improved the accuracy in water density quantification, in comparison with that from the theoretical conversion. The results show that conversion of the dual energy measurements into water and lipid thicknesses improves the accuracy in breast tissue decomposition.


Assuntos
Neoplasias da Mama/metabolismo , Mama/metabolismo , Calibragem , Lipídeos/análise , Mamografia/métodos , Imagens de Fantasmas , Água/química , Autopsia , Mama/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Análise dos Mínimos Quadrados , Modelos Lineares , Fótons , Mudanças Depois da Morte
4.
Br Poult Sci ; 58(3): 272-277, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28100065

RESUMO

1. A dose-response experiment was conducted with male Korean native ducklings (KND) to evaluate the total sulphur amino acid (TSAA) requirement from hatch to 21 d of age. 2. A completely randomised design with 7 dietary TSAA concentrations (0.62%, 0.65%, 0.68%, 0.71%, 0.74%, 0.77% and 0.80%) were used with 6 replications per treatment. 3. Body weight (BW) and feed intake were measured weekly to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR). One duckling per pen (n = 6) was killed by cervical dislocation to weigh empty body and drumsticks at the conclusion of experiment. 4. BW was improved significantly with increasing TSAA content, in a non-linear manner. A significant decrease of FCR was shown with increasing TSAA contents. TSAA requirement was determined by taking a mean value after fitting the data to both a linear-plateau and a quadratic-plateau model. Estimated TSAA requirements were 0.70%, 0.70%, 0.66% and 0.70% for the maximum BW, ADG and ADFI and for the minimum FCR, respectively. Increasing TSAA content improved quantity of full body weight (FBW), empty body weight (EBW) and drumstick weight (DSW), but there was no effect on proportion of DSW in relation to EBW and proportion of EBW to FBW. 5. In conclusion, the growth of male KND during 1 to 21 d of age was improved with increasing TSAA content, suggesting optimal TSAA requirements estimated by two analysis models.


Assuntos
Aminoácidos Sulfúricos/metabolismo , Patos/fisiologia , Metabolismo Energético , Necessidades Nutricionais , Aumento de Peso , Ração Animal/análise , Animais , Dieta/veterinária , Relação Dose-Resposta a Droga , Patos/genética , Patos/crescimento & desenvolvimento , Masculino , Distribuição Aleatória
5.
J Visc Surg ; 153(5): 339-345, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27179763

RESUMO

AIM OF THE STUDY: Compared with patients with other benign intestinal conditions, patients with CD are at increased risk of developing postoperative complications following intestinal resection. We searched for useful tools for predicting postoperative complication in patients with CD by comparing the relationship between postoperative morbidity in these patients as measured by three different scoring tools: general surgical risk (POSSUM score), disease activity (CDAI), and nutritional screening (nutritional prognostic index). METHODS: We performed a retrospective review of 50 patients with small bowel CD who underwent surgical resection and primary anastomosis between 1999 and 2014. RESULTS: This study enrolled 34 men and 16 women. The mean age was 38.4 years (range: 20-81 years). There was no postoperative mortality. The overall postoperative morbidity rate (33.7%) predicted by POSSUM was similar to the rate in the study patients (36.0%). Although POSSUM score predicted higher postoperative morbidity rates in patients who underwent emergency surgery (estimated morbidity: 52.8%), the actual postoperative morbidity rate in the emergency surgery group (26.7%) was smaller than in the elective surgery group (40.0%). In addition, neither preoperative nutritional status nor POSSUM score was related to the severity of postoperative complications. CDAI score was significantly related to the severity of postoperative complications (P=0.032). CONCLUSION: Based on the above results, a high preoperative CDAI score can predict negative postoperative outcomes. We believe that disease activity should be controlled using various treatment modalities, such as enteral or total parenteral nutrition as well as medication, before performing surgery in patients with CD.


Assuntos
Doença de Crohn/cirurgia , Procedimentos Cirúrgicos do Sistema Digestório/métodos , Procedimentos Cirúrgicos Eletivos/métodos , Intestino Delgado/cirurgia , Complicações Pós-Operatórias/epidemiologia , Medição de Risco/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Anastomose Cirúrgica/métodos , Doença de Crohn/diagnóstico , Técnicas de Apoio para a Decisão , Feminino , Seguimentos , Humanos , Intestino Delgado/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Morbidade/tendências , Curva ROC , República da Coreia/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença , Taxa de Sobrevida/tendências , Adulto Jovem
6.
Phys Med ; 32(1): 213-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26494155

RESUMO

In this work, we propose a practical method that can combine the two functionalities of dental panoramic and cone-beam CT (CBCT) features in one by using a single panoramic detector. We implemented a CS-based reconstruction algorithm for the proposed method and performed a systematic simulation to demonstrate its viability for 3D dental X-ray imaging. We successfully reconstructed volumetric images of considerably high accuracy by using a panoramic detector having an active area of 198.4 mm × 6.4 mm and evaluated the reconstruction quality as a function of the pitch (p) and the angle step (Δθ). Our simulation results indicate that the CS-based reconstruction almost completely recovered the phantom structures, as in CBCT, for p≤2.0 and θ≤6°, indicating that it seems very promising for accurate image reconstruction even for large-pitch and few-view data. We expect the proposed method to be applicable to developing a cost-effective, volumetric dental X-ray imaging system.


Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Imageamento Tridimensional/métodos , Boca/diagnóstico por imagem , Radiografia Dentária/métodos , Algoritmos , Simulação por Computador , Análise Custo-Benefício , Compressão de Dados , Humanos , Modelos Teóricos , Imagens de Fantasmas , Interpretação de Imagem Radiográfica Assistida por Computador , Reprodutibilidade dos Testes , Dente/diagnóstico por imagem , Raios X
7.
J Geophys Res Atmos ; 121(12): 7007-7025, 2016 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-32908807

RESUMO

The bi-spectral method retrieves cloud optical thickness (τ) and cloud droplet effective radius (r e ) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved τ and r e . In the literature, the retrievals of τ and r e are often assumed to be independent and considered separately when investigating the impact of sub-pixel cloud reflectance variations on the bi-spectral method. As a result, the impact on τ is contributed only by the sub-pixel variation of VIS/NIR band reflectance and the impact on r e only by the sub-pixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the τ and r e retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the τ and r e retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the r e retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in r e retrievals, leading to a potential contribution of positive bias to the r e retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from MODIS. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used to estimate the retrieval uncertainty from sub-pixel reflectance variations in operational satellite cloud products and to help understand the differences in τ and r e retrievals between two instruments.

8.
Science ; 348(6241): 1344-7, 2015 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-26089511

RESUMO

Topological defects can markedly alter nanomaterial properties. This presents opportunities for "defect engineering," where desired functionalities are generated through defect manipulation. However, imaging defects in working devices with nanoscale resolution remains elusive. We report three-dimensional imaging of dislocation dynamics in individual battery cathode nanoparticles under operando conditions using Bragg coherent diffractive imaging. Dislocations are static at room temperature and mobile during charge transport. During the structural phase transformation, the lithium-rich phase nucleates near the dislocation and spreads inhomogeneously. The dislocation field is a local probe of elastic properties, and we find that a region of the material exhibits a negative Poisson's ratio at high voltage. Operando dislocation imaging thus opens a powerful avenue for facilitating improvement and rational design of nanostructured materials.

9.
Eur J Trauma Emerg Surg ; 41(4): 375-85, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26037988

RESUMO

PURPOSE: The aim of this study was to examine prognostic factors in polytraumatic patients with liver injury and to develop a scoring system for traumatic liver injury (SSTLI) to predict mortality. METHODS: The medical records of 175 patients treated for traumatic liver injury from July 2009 to April 2013 were reviewed. The primary outcome variable was hospital mortality. All risk factors were analyzed by multivariate logistic regression analysis. The SSTLI was created based on the predictive power of each factor. RESULTS: Age, injury severity score (ISS), trauma and injury severity score, the shock index, and the volume of packed red blood cells transfused were strong predictors of mortality. We hypothesized that the SSTLI would use five clinical measures (total bilirubin, prothrombin time, serum creatinine, age, and ISS). Each measure was scored 0-1 (age and ISS) or 0-3 (total bilirubin, prothrombin time, and creatinine), with 3 indicating the most severe derangement. The receiver-operating characteristic curve of the SSTLI was significant at post-traumatic days 0, 1, 3, and 5 [area under the curve (AUC), 0.830; AUC, 0.912; AUC, 0.941; and AUC, 0.930, respectively]. A value of 5 points was the threshold for reliability dividing low-risk (<5) from high-risk (≥5) patients. CONCLUSIONS: The SSTLI may be available to predict mortality in polytraumatic patients with liver injury, although external validation is needed before widespread implementation.


Assuntos
Causas de Morte , Fígado/lesões , Traumatismo Múltiplo/mortalidade , Índices de Gravidade do Trauma , Traumatismos Abdominais/diagnóstico , Traumatismos Abdominais/mortalidade , Traumatismos Abdominais/cirurgia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Área Sob a Curva , Bases de Dados Factuais , Feminino , Mortalidade Hospitalar/tendências , Humanos , Fígado/cirurgia , Masculino , Pessoa de Meia-Idade , Traumatismo Múltiplo/diagnóstico , Traumatismo Múltiplo/cirurgia , Valor Preditivo dos Testes , Curva ROC , Estudos Retrospectivos , Medição de Risco , Fatores Sexuais , Análise de Sobrevida , Estados Unidos , Adulto Jovem
10.
Phys Chem Chem Phys ; 17(16): 10551-5, 2015 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-25804979

RESUMO

Lithium ion batteries are the dominant form of energy storage in mobile devices, increasingly employed in transportation, and likely candidates for renewable energy storage and integration into the electrical grid. To fulfil their powerful potential, electrodes with increased capacity, faster charge rates, and longer cycle life must be developed. Understanding the mechanics and chemistry of individual nanoparticles under in situ conditions is a crucial step to improving performance and mitigating damage. Here we reveal three-dimensional strain evolution within a single nanoparticle of a promising high voltage cathode material, LiNi0.5Mn1.5O4, under in situ conditions. The particle becomes disconnected during the second charging cycle. This is attributed to the formation of a cathode electrolyte interphase layer with slow ionic conduction. The three-dimensional strain pattern within the particle is independent of cell voltage after disconnection, indicating that the particle is unable to redistribute lithium within its volume or to its neighbours. Understanding the disconnection process at the single particle level and the equilibrium or non-equilibrium state of nanoparticles is essential to improving performance of current and future electrochemical energy storage systems.

11.
Analyst ; 140(3): 706-9, 2015 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-25453038

RESUMO

A novel, solution immersed silicon (SIS)-based sensor has been developed which employs the non-reflecting condition (NRC) for a p-polarized wave. The SIS sensor's response is almost independent of change in the refractive index (RI) of a buffer solution (BS) which makes it capable of measuring low-concentration and/or low-molecular-weight compounds.


Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Refratometria/métodos , Silício/química , Soluções
12.
Phys Med Biol ; 59(23): 7211-27, 2014 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-25369288

RESUMO

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm(2) in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.


Assuntos
Algoritmos , Fótons , Espectrometria por Raios X/normas , Calibragem , Estudos de Viabilidade , Espectrometria por Raios X/instrumentação
13.
Cell Death Dis ; 4: e919, 2013 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-24232095

RESUMO

Genetic and epidemiologic evidence suggests that cellular energy homeostasis is critically associated with Parkinson's disease (PD) pathogenesis. Here we demonstrated that genetic deletion of Poly (ADP-ribose) polymerase 1 completely blocked 6-hydroxydopamine-induced dopaminergic neurodegeneration and related PD-like symptoms. Hyperactivation of PARP-1 depleted ATP pools in dopaminergic (DA) neurons, thereby activating AMP-activated protein kinase (AMPK). Further, blockade of AMPK activation by viral infection with dominant-negative AMPK strongly inhibited DA neuronal atrophy with moderate suppression of nuclear translocation of apoptosis-inhibiting factor (AIF), whereas overactivation of AMPK conversely strengthened the 6-OHDA-induced DA neuronal degeneration. Collectively, these results suggest that manipulation of PARP-1 and AMPK signaling is an effective therapeutic approach to prevent PD-related DA neurodegeneration.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Dopamina/metabolismo , Neurônios/citologia , Doença de Parkinson/enzimologia , Doença de Parkinson/patologia , Proteínas Quinases Ativadas por AMP/genética , Animais , Western Blotting , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Masculino , Espectrometria de Massas , Camundongos , Camundongos Knockout , Neurônios/metabolismo , Doença de Parkinson/metabolismo , Poli(ADP-Ribose) Polimerases/genética , Poli(ADP-Ribose) Polimerases/metabolismo
14.
Phys Rev Lett ; 111(14): 141301, 2013 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-24138230

RESUMO

Gravitational lensing of the cosmic microwave background generates a curl pattern in the observed polarization. This "B-mode" signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals. In this Letter we present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the South Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic infrared background. We compare this template to the B modes measured directly by SPTpol, finding a nonzero correlation at 7.7σ significance. The correlation has an amplitude and scale dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.

15.
Phys Med Biol ; 58(14): 4865-79, 2013 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-23787497

RESUMO

The purpose of this paper was to investigate the effect of photon flux on the recorded energy spectrum and images produced with a photon-counting detector. We used a photon-counting cadmium telluride (CdTe) x-ray detector (model PID350, Oy Ajat, Finland). The CdTe array was composed of 16 384 pixels, each 0.35 × 0.35 × 0.75 mm(3) in dimension. The photon flux is controlled by an additional aluminum filter (1, 10, 20, 30 and 40 mm). Images were acquired at three different tube voltages (50, 70 and 90 kVp) with various thicknesses of photon flux control (PFC) filters. The data acquisition time was changed to acquire an approximately equal number of counts within the selected energy window between different thicknesses of PFC filters at the same tube voltage. A phantom was manufactured to evaluate the photon flux effect on the image. The phantom was made from polymethyl methacrylate and four concentrations of iodine. The photon flux effect on the image was evaluated by the signal-difference-to-noise ratio (SDNR) between iodine and the background material. The changes of photon flux affected the recorded energy spectra and image. The thickness of the PFC filter that showed the maximum SDNR differed according to the tube voltage. The 10 mm PFC filter showed the highest SDNR at 50 and 70 kVp, while the 30 mm PFC filter exhibited the highest SDNR at 90 kVp. The SDNR was improved up to, on average, 30-fold in optimal photon flux conditions which acquired a spectrum including the lowest electronic noise with no pulse pile-up effect. The results of this study showed that the photon flux affected not only the acquired energy spectrum but also the image. Based on these results, the spectral distortion correction should be considered in connection with the image that is the ultimate purpose of medical imaging.


Assuntos
Fótons , Tomografia Computadorizada por Raios X/métodos , Compostos de Cádmio , Imagens de Fantasmas , Telúrio
16.
Phys Rev Lett ; 110(14): 147002, 2013 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-25167026

RESUMO

The spectral density S(Φ)(f) = A(2)/(f/1 Hz)(α) of magnetic flux noise in ten dc superconducting quantum interference devices (SQUIDs) with systematically varied geometries shows that α increases as the temperature is lowered; in so doing, each spectrum pivots about a nearly constant frequency. The mean-square flux noise, inferred by integrating the power spectra, grows rapidly with temperature and at a given temperature is approximately independent of the outer dimension of a given SQUID. These results are incompatible with a model based on the random reversal of independent, surface spins.

17.
Rev Sci Instrum ; 83(7): 073113, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22852677

RESUMO

A technological milestone for experiments employing transition edge sensor bolometers operating at sub-Kelvin temperature is the deployment of detector arrays with 100s-1000s of bolometers. One key technology for such arrays is readout multiplexing: the ability to read out many sensors simultaneously on the same set of wires. This paper describes a frequency-domain multiplexed readout system which has been developed for and deployed on the APEX-SZ and South Pole Telescope millimeter wavelength receivers. In this system, the detector array is divided into modules of seven detectors, and each bolometer within the module is biased with a unique ∼MHz sinusoidal carrier such that the individual bolometer signals are well separated in frequency space. The currents from all bolometers in a module are summed together and pre-amplified with superconducting quantum interference devices operating at 4 K. Room temperature electronics demodulate the carriers to recover the bolometer signals, which are digitized separately and stored to disk. This readout system contributes little noise relative to the detectors themselves, is remarkably insensitive to unwanted microphonic excitations, and provides a technology pathway to multiplexing larger numbers of sensors.

18.
Nature ; 488(7411): 349-52, 2012 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-22895340

RESUMO

In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

19.
Colorectal Dis ; 14(7): e378-85, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22288509

RESUMO

AIM: Brain metastasis is infrequent in colorectal cancer patients, and the prognosis is poor. In this retrospective study survival and prognostic factors were determined in patients with brain metastasis from colorectal cancer. METHOD: Between 1997 and 2006, 39 patients with brain metastasis from colorectal cancer who survived more than 1 month were identified. Data were collected with regard to patient characteristics, location and stage of the primary tumour, extent and location of metastatic disease, and treatment modalities used. RESULTS: Most (79.5%) patients had pulmonary metastases before brain metastasis, and the brain was the site of solitary metastasis in only one patient. The most frequent symptom was weakness [18 (43.6%) patients]. Overall median survival was 5.0 months and the 1- and 2-year survival rates were 21.8 and 9.1%, respectively. Univariate analysis revealed uncontrolled extracranial metastases (P = 0.019), multiple brain lesions (P = 0.026), bilateral brain metastases (P = 0.032) and serum carcinoembryonic antigen levels greater than 5 ng/ml (P = 0.008) to be poor prognostic factors. The median survival after the diagnosis of brain metastasis was significantly longer in patients who underwent surgical resection (15.2 ± 8.0 months) than in those treated by other modalities (P = 0.001). Treatment modality was the only independent prognostic factor for overall survival in patients with brain metastases from colorectal cancers (P = 0.015). CONCLUSION: Aggressive surgical resection in selected patients with brain metastases from colorectal cancer may prolong survival, even in the presence of extracranial metastatic lesions.


Assuntos
Neoplasias Encefálicas/secundário , Neoplasias Encefálicas/cirurgia , Neoplasias do Colo/patologia , Neoplasias Retais/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Neoplasias Encefálicas/diagnóstico , Antígeno Carcinoembrionário/sangue , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida
20.
Rev Sci Instrum ; 82(9): 091301, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21974566

RESUMO

The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 µK(CMB)√s (NEy of 3.5 × 10(-4) √s). We have also demonstrated upgraded detectors with improved sensitivity of 530 µK(CMB)√s (NEy of 2.2 × 10(-4) √s). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.

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