Observation of inverse Compton emission from a long γ-ray burst.

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission1,2. Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands1-6. The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock7-9. Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C10,11. Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10-6 to 1012 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs.

Pleural fluid adenosine deaminase to serum C-reactive protein ratio for diagnosing tuberculous pleural effusion.

BACKGROUND: Tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE) may occasionally show similar cytological and biochemical picture including ADA. In such cases, differentiating TPE and MPE is challenging and needs histopathology of pleural tissue which may involve invasive procedures. The present study aims to evaluate the diagnostic accuracy of pleural fluid ADA to serum CRP (ADA/CRP) ratio to discriminate between tuberculous and malignant pleural effusion. In addition, we investigated whether the ratio ADA/CRP adds diagnostic value to ADA. METHODS: This cross-sectional study was conducted in the National Institute of Diseases of the Chest and Hospital (NIDCH), Mohakhali, Dhaka, from July 2021 to February 2022 on diagnosed patients of TPE and malignant pleural effusion MPE. A receiver operating characteristic curve (ROC) was constructed for identifying TPE. The added value of the ADA/CRP ratio to ADA was evaluated using the net reclassification improvement (NRI) and integrated discrimination improvement (IDI). A value of p < 0.05 was considered statistically significant for all tests. RESULTS: Fifty-nine patients were enrolled in this study, of which 31 had TPE, and 28 had MPE. Pleural fluid ADA to serum CRP ratio and pleural fluid ADA level was significantly higher in patients with TPE, but there was no significant difference in serum CRP levels between patients with TPE and MPE. At cut off value of > 1.25, pleural fluid ADA to serum CRP ratio had a sensitivity of 93.8%, specificity of 85.2%, and positive and negative predictive values were 88.2% and 92% respectively, in the diagnosis of TPE and area under ROC curve (AUC) was 0.94. The NRI and IDI analyses revealed added diagnostic value of ADA/CRP to ADA. CONCLUSION: This study shows that the ADA/CRP ratio improves the diagnostic usefulness of ADA for TPE.

ULTRASOUND SPECTROSCOPY.

We introduce the concept of "Ultrasound Spectroscopy". The premise of ultrasound spectroscopy is that by acquiring ultrasound RF data at multiple power and frequency settings, a rich set of features can be extracted from that RF data and used to characterize the underlying tissues. This is beneficial for a variety of problems, such as accurate tissue classification, application-specific image generation, and numerous other quantitative tasks. These capabilities are particularly relevant to point-of-care ultrasound (POCUS) applications, where operator experience with ultrasound may be limited. Instead of displaying B-mode images, a POCUS application using ultrasound spectroscopy can, for example, automatically detect internal abdominal bleeding. In this paper, we present ex vivo tissue phantom studies to demonstrate the accuracy of ultrasound spectroscopy over previous approaches. Our studies suggest that ultrasound spectroscopy provides exceptional accuracy and informative features for classifying blood versus other tissues across image locations and body habitus.

Does rheumatic fever occur usually between the ages of 5 and 15 years?

It has long been considered that rheumatic fever usually occurs in children between the ages of 5 and 15 years. However, supporting data from the developing countries are insufficient. It is important to know the age of occurrence of rheumatic fever for clinical and public health purposes. To describe the age distribution of Bangladeshi subjects, we have reviewed the records of all patients who attended with acute rheumatic fever in the outpatient department of the National Center for Control of Rheumatic Fever and Heart Diseases, Dhaka, during June 1990 through November 1995. During this period 630 subjects were diagnosed to have acute rheumatic fever defined by the revised Jones criteria. Of them, 535 (84.9%) presented with first attack. Their age ranged from 3 to 30 years, and a skewness to the right of the age distribution was observed. Thus, we used percentile distribution to determine reference range of age. The 2.5 and 97.5 percentiles were 5 and 22 years, respectively. Their mean (standard deviation) and median age were 12.7 (4.4) and 12 years, respectively. Slightly more than 22% of subjects were older than 15 while less than 1% were younger than 5 years. This finding was supported by multiethnic data from other developing countries. The current analysis warrants reevaluation of the prevailing conviction for age of occurrence of rheumatic fever. In conclusion, the age reference range for occurrence of rheumatic fever in Bangladesh should be considered to be 5 to 22 years but not 5 to 15 years.

Effects of pulse separation on detection thresholds for electrical stimulation of the human cochlea.

Effects of pulse separation on detection of electrical stimulation of the cochlea were studied in 12 profoundly deaf human subjects with Nucleus 22 cochlear implants. Biphasic symmetric pulses were used. Pulse separation is the time from offset of one biphasic pulse to the onset of the next biphasic pulse in the train. Effects of pulse separation were studied in the context of different covariables in four stages of the experiment. Effects of pulse separation seen in the different stages were similar, despite the different covariables. Both pulse separation and the total number of pulses per stimulus seem to be important variables affecting stimulus detection. For 0.5 ms/phase pulses, thresholds were lowest at the shortest pulse separations tested (0.2-1.1 ms) and increased as a function of pulse separation. For 2 ms/phase pulses, detection thresholds were lowest at pulse separations around 7.5 ms, in most cases, and higher at both longer and shorter pulse separations. These results suggest that interactions among adjacent pulses can either hinder or facilitate detection of the signal depending on the magnitudes of pulse separation and phase duration. Pulse separations at which thresholds measured for 2 ms/phase pulses were minimum were fairly consistent across subjects and did not correlate well with speech recognition scores. However, significant variation in this measure across species has been seen.

Bacteriuria and urinary tract infection in pregnancy.

The incidence of bacteriuria among 300 pregnant and 100 married, non-pregnant women (control group) were studied. Clean voided mid-stream urine were collected aseptically. Significant bacteriuria was noted 15 (5%) cases among the pregnant women. Of these, only 4 had symptoms suggestive of urinary tract infection. In the control group, only one significant bacteriuria case was detected. Seven different types of microorganisms were isolated from the cases showing significant bacteriuria. The predominant organisms were Esch. coli and Kleb. pneumoniae. No distinct correlation between bacteriuria and pyuria was observed. The results have been discussed.

Localizing target structures in ultrasound video - a phantom study.

The problem of localizing specific anatomic structures using ultrasound (US) video is considered. This involves automatically determining when an US probe is acquiring images of a previously defined object of interest, during the course of an US examination. Localization using US is motivated by the increased availability of portable, low-cost US probes, which inspire applications where inexperienced personnel and even first-time users acquire US data that is then sent to experts for further assessment. This process is of particular interest for routine examinations in underserved populations as well as for patient triage after natural disasters and large-scale accidents, where experts may be in short supply. The proposed localization approach is motivated by research in the area of dynamic texture analysis and leverages several recent advances in the field of activity recognition. For evaluation, we introduce an annotated and publicly available database of US video, acquired on three phantoms. Several experiments reveal the challenges of applying video analysis approaches to US images and demonstrate that good localization performance is possible with the proposed solution.