Single Occult Research Articles

X-ray occultations in active galactic nuclei: Physical properties of eclipsing clouds as part of the broad-line region cloud ensemble

Context. Short-term X-ray variability in active galactic nuclei (AGNs) can be explained as being due to varying X-ray absorption induced by the temporary occultation of the primary X-ray source, when moving absorbing clouds cross the line of sight to the X-ray source itself. Earlier work suggests that these absorbing clouds have physical properties similar to those of broad-line region (BLR) emitting clouds and are located in the same spatial region. Aims. We intend to extract physical information on each individual absorber associated with any given occultation event detected in our sample and to analyse general properties of the cloud ensemble whose components can produce X-ray eclipses. Methods. From the analysis of previously detected occultation events, two ‘observables’ characterising each single occultation event can be derived: the peak fractional hardness ratio variation (ΔHR/HR) and the duration of the event normalised by a characteristic eclipse timescale evaluated for each AGN source. To determine the eclipsing cloud properties, we devised a procedure a) based on simplifying assumptions on the geometry of both the X-ray source and the cloud-like gas condensations, and on the cloud X-ray absorbing properties in the energy range of interest (2–10 keV), and b) relying on a set of simulated instrumental responses from both XMM and Suzaku relevant instruments to different incoming X-ray spectra, absorbed with varying absorber column density and maximum covering factor during the occultation. Thus, we derived information on the individual cloud producing any given occultation event, determining the cloud radius normalised to that of the X-ray source, the spatial location of the cloud, and an estimate of the cloud gas number density for reasonable values of the equivalent absorber column density. Results. The physical properties of eclipsing clouds that we obtained are consistent with those of BLR clouds. We can exclude the dominance, in the ensemble cloud size distribution, of clouds larger than about 10–12 times the Schwarzschild radius characterising each AGN, and we do not find any significant dependence of the cloud physical size on the distance from the central black hole, in agreement with the results of our previous work. As for the number density of these gas condensations, with our procedure we obtained values within a range of ∼109 − 1011 cm−3, which is consistent with the estimates derived from broad emission line analysis.

Indications for Adjuvant (Chemo) Radiotherapy in Vulvar Cancer with Groin Lymph Node Metastases

Guidelines recommend adjuvant treatment when positive lymph nodes are found after surgical treatment for squamous cell cancer of the vulva except for cases with a single occult intranodal metastasis. Recent studies questioned these recommendations and showed benefit of adjuvant radiotherapy for all patients with positive nodes irrespective of number of nodes. However, these studies did not take into account important nodal characteristics, such as clinical node status, extranodal spread or size of the metastasis. When these variables are taken into account, adjuvant radiotherapy does not seem to result in a better survival for patients with a single occult intranodal metastasis. Whether the addition of chemotherapy to the radiotherapy for patients with more than one positive node or extracapsular spread results in a better survival remains uncertain. Only a few studies have been published on this subject and come to the conclusion that adding chemotherapy results in a better survival. The conclusion is that adjuvant radiotherapy improves survival of patients with positive groin nodes, with the exception of patients with a single intranodal metastasis. The beneficial effect of chemo radiotherapy for subgroups of patients with positive nodes seems likely, although more data are needed before a definite conclusion can be made

Radiotherapy is not indicated in patients with vulvar squamous cell carcinoma and only one occult intracapsular groin node metastasis

ObjectiveMost guidelines advise no adjuvant radiotherapy in vulvar squamous cell carcinoma and a single occult intracapsular lymph node metastasis. However, several recent studies have questioned the validity of this recommendation. The aim of this study was to analyze the groin recurrence rate in patients with a single intracapsular positive lymph node treated without adjuvant radiotherapy. MethodsPatients with a single clinically occult intracapsular lymph node metastasis, treated without adjuvant radiotherapy, formed the basis for this study. Groin recurrences, and the risk of death, were analyzed in relation to the size of the metastasis in the lymph node and the lymph node ratio. Data were analyzed using SPSS, version 26.0 for Windows. ResultsAfter a median follow-up of 64 months, one of 96 patients (1%) was diagnosed with an isolated groin recurrence and another two (2.1%) were diagnosed with a combination of a local and a groin recurrence. The only isolated groin recurrence occurred in a contralateral lymph node negative groin. Size of the metastasis and lymph node ratio had no impact on the groin recurrence risk, nor on survival. The 5-year actuarial disease-specific and overall survivals were 79% and 62.5% respectively. The 5-year actuarial groin recurrence-free survival was 97%. ConclusionBecause of the low risk of groin recurrence and the excellent groin recurrence-free survival, we recommend that adjuvant radiotherapy to the groin in patients with vulvar squamous cell carcinoma and a single occult intracapsular lymph node metastasis can be safely omitted to prevent unnecessary toxicity and morbidity.

Concomitant Hyperparathyroidism Due to Occult Parathyroid Adenoma Detected by Technetium-99m Sestamibi Single-photon Computed Tomography/Computerized Tomography in a Patient with Papillary Thyroid Carcinoma

Although the occurrence of thyroid and parathyroid diseases is common, concomitant parathyroid adenoma and papillary thyroid carcinoma is rare. We report the case of a 77-year-old Thai woman who was diagnosed to have papillary thyroid carcinoma and postoperative hypercalcemia. The primary hyperparathyroidism was initially overlooked but was subsequently confirmed to be due to a single occult parathyroid adenoma demonstrated on technetium99m sestamibi (Tc-99m MIBI) parathyroid scintigraphy. Thus, preoperative evaluation of parathyroid disease should be performed if there is evidence of hypercalcemia prior to the thyroid surgery. Presurgical evaluation with Tc-99m MIBI parathyroid single-photon computed tomography/computerized tomography imaging has a definite role in localizing a hyperfunctioning parathyroid gland in the cases of primary hyperparathyroidism.

Pathology Evaluation of Reduction Mammaplasty Specimens and Subsequent Diagnosis of Malignant Breast Disease: A Claims-Based Analysis.

This study aimed to measure the use of pathology evaluation of breast specimens among patients undergoing reduction mammaplasty and assess rates of new diagnoses of breast disease and associated cost. We analyzed the Truven MarketScan Databases from 2009 to 2015 to identify adult female patients undergoing reduction mammaplasty for macromastia. We recorded patient age, rates of obtaining pathology evaluation, new diagnoses of benign or malignant breast disease after pathology evaluation, and total cost for the surgery encounter. Among 17,738 macromastia patients undergoing reduction mammaplasty, 91.3% (n = 16,193) received pathology evaluation. Pathology evaluation rates were clinically similar across age groups <70years (90.8-92.1%) and slightly lower for patients ≥70 (85.0%). Among 6987 patients less than 40years who received pathology evaluation, 0.06% (n = 4) were subsequently diagnosed with malignant breast disease within 3months, compared to 0.23% in the entire cohort (n = 37/16,193). Pathology claims resulted in an added $307 (SD 251) on average for the breast reduction surgery encounters. Breast tissue after reduction mammaplasty is routinely submitted for pathology evaluation, without consideration of age-based risk for breast cancer. Routine pathology evaluation of breast tissue in patients in lower risk age groups (less than 40years) required an additional $536,000 on average to detect a single occult breast cancer compared to an added $85,600 to detect a new malignancy in patients 40years and older. Clinicians and policy makers should consider whether routine pathology evaluation of breast tissue should be individualized based on risk factors for breast cancer.

A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes

Kuiper belt objects (KBOs) are thought to be the remnant of the early solar system, and their size distribution provides an opportunity to explore the formation and evolution of the outer solar system. In particular, the size distribution of kilometre-sized (radius = 1-10 km) KBO represents a signature of initial planetesimal sizes when planets form. These kilometre-sized KBOs are extremely faint, and it is impossible to detect them directly. Instead, monitoring of stellar occultation events is one possible way to discover these small KBOs. Hitherto, however, there has been no observational evidence for the occultation events by KBOs with radii of 1-10 km. Here we report the first detection of a single occultation event candidate by a KBO with a radius of $\sim$1.3 km, which is simultaneously provided by two low-cost small telescopes coupled with commercial CMOS cameras. From this detection, we conclude that a surface number density of KBOs with radii exceeding $\sim 1.2$ km is $\sim 6 \times 10^5 \ {\rm deg^{-2}}$. This surface number density favours a theoretical size distribution model with an excess signature at a radius of 1-2 km. If this is a true detection, this implies that planetesimals before their runaway growth phase grow into kilometre-sized objects in the primordial outer solar system and remain as a major population of the present-day Kuiper belt.

Features in the broad-band eclipse spectra of exoplanets: signal or noise?

A planet's emission spectrum contains information about atmospheric composition and structure. We compare the Bayesian Information Criterion (BIC) of blackbody fits and idealized spectral retrieval fits for the 44 planets with published eclipse measurements in multiple thermal wavebands, mostly obtained with the Spitzer Space Telescope. The evidence for spectral features depends on eclipse depth uncertainties. Spitzer has proven capable of eclipse precisions better than 1E-4 when multiple eclipses are analyzed simultaneously, but this feat has only been performed four times. It is harder to self-calibrate photometry when a single occultation is reduced and analyzed in isolation; we find that such measurements have not passed the test of repeatability. Single-eclipse measurements either have an uncertainty floor of 5E-4, or their uncertainties have been underestimated by a factor of 3. If one adopts these empirical uncertainties for single-eclipse measurements, then the evidence for molecular features all but disappears: blackbodies have better BIC than spectral retrieval for all planets, save HD 189733b, and the few planets poorly fit by blackbodies are also poorly fit by self-consistent radiative transfer models. This suggests that the features in extant broadband emission spectra are due to astrophysical and instrumental noise rather than molecular bands. Claims of stratospheric inversions, disequilibrium chemistry, and high C/O ratios based solely on photometry are premature. We recommend that observers be cautious of error estimates from self-calibration of small data sets, and that modelers compare the evidence for spectral models to that of simpler models such as blackbodies.

Congenital Fusion of the Thalami (Atresia of the Third Ventricle) Associated with Parietooccipital Meningocele

In this article we present a case of a male newborn with a CNS malformation that is characterized mainly by complete fusion of the thalami resulting in atresia of the 3rd ventricle accompanied by fusion of the anterior peduncles of the fornix, the presence of a single occult interventricular foramen lying at the midline, absence of the septum pellucidum, hypoplasia of the corpus callosum, disorganization of the head of the left caudate nucleus, and greatly dilated lateral ventricles (hydrocephalus). The patient underwent surgical correction of the meningocele on his 4th postnatal day. On his 13th postnatal day he had projectile vomiting due to a left parietooccipital hygroma that was drained via a shunt. On his 31st postnatal day he developed seizures and marked dilatation of the lateral ventricles, for which he underwent a ventriculoperitoneal shunt (Brown). On the 14th postoperative day the patient developed aspiration pneumonia and died.

Uranus and Neptune: Shape and rotation

Both Uranus and Neptune are thought to have strong zonal winds with velocities of several 100 m s −1. These wind velocities, however, assume solid-body rotation periods based on Voyager 2 measurements of periodic variations in the planets’ radio signals and of fits to the planets’ magnetic fields; 17.24 h and 16.11 h for Uranus and Neptune, respectively. The realization that the radio period of Saturn does not represent the planet’s deep interior rotation and the complexity of the magnetic fields of Uranus and Neptune raise the possibility that the Voyager 2 radio and magnetic periods might not represent the deep interior rotation periods of the ice giants. Moreover, if there is deep differential rotation within Uranus and Neptune no single solid-body rotation period could characterize the bulk rotation of the planets. We use wind and shape data to investigate the rotation of Uranus and Neptune. The shapes (flattening) of the ice giants are not measured, but only inferred from atmospheric wind speeds and radio occultation measurements at a single latitude. The inferred oblateness values of Uranus and Neptune do not correspond to bodies rotating with the Voyager rotation periods. Minimization of wind velocities or dynamic heights of the 1 bar isosurfaces, constrained by the single occultation radii and gravitational coefficients of the planets, leads to solid-body rotation periods of ∼16.58 h for Uranus and ∼17.46 h for Neptune. Uranus might be rotating faster and Neptune slower than Voyager rotation speeds. We derive shapes for the planets based on these rotation rates. Wind velocities with respect to these rotation periods are essentially identical on Uranus and Neptune and wind speeds are slower than previously thought. Alternatively, if we interpret wind measurements in terms of differential rotation on cylinders there are essentially no residual atmospheric winds.

Comparative study on the clinical and virological characteristics among patients with single occult hepatitis B virus (HBV), single occult hepatitis C virus (HCV) and occult HBV and HCV dual infection

Occult hepatitis B virus (HBV) and occult hepatitis C virus (HCV) infection are two recently described different forms of HBV and HCV infections. This work compares the clinical, virologic, and histologic characteristics of patients with occult dual infection to those of patients with single occult HBV or HCV infection. Seventy-six patients with abnormal liver function tests of unknown etiology (serum HBsAg, anti-HCV, HBV-DNA, and HCV-RNA negative) were included in the study. Viral genomes were tested in liver by real-time PCR and confirmed by in situ hybridization. Of the 76 patients, 17 had occult HBV infection (intrahepatic HBV-DNA positive, HCV-RNA negative), 35 had occult HCV infection (intrahepatic HCV-RNA positive, HBV-DNA negative) and 24 occult dual infection (intrahepatic HCV-RNA and HBV-DNA). No differences among the three groups were found regarding clinical and epidemiologic data. The median load of intrahepatic genomic and antigenomic HCV-RNA strands was similar between single occult HCV infection and occult HBV and HCV dual infection. The percentage of HCV-infected hepatocytes did not differ between these groups. In occult single HBV infection, intrahepatic levels of HBV-DNA and percentage of HBV-infected hepatocytes were similar to the group of patients with occult dual infection. Finally, no differences were found in histological liver damage among the three groups. In conclusion, liver disease in patients with occult dual infection was not more severe than in patients with single occult HBV or occult HCV infection. Moreover, in occult dual infection there is no a reciprocal inhibition of the viral genomes.

First space-borne measurements of methanol inside aged southern tropical to mid-latitude biomass burning plumes using the ACE-FTS instrument

Abstract. First measurements from space of upper tropospheric and lower stratospheric methanol profiles within aged fire plumes are reported. Elevated levels of methanol at 0–45° S from 30 September to 3 November 2004 have been measured by the high resolution infrared spectrometer ACE-FTS onboard the SCISAT satellite. Methanol volume mixing ratios higher than 4000 pptv are detected and are strongly correlated with other fire products such as CO, C2H6, and HCN. A sensitivity study of the methanol retrieval, accounting for random and systematic contributions, shows that the retrieved methanol profile for a single occultation exceeds 100% error above 16.5 km, with an accuracy of about 20% for measurements inside polluted air masses. The upper tropospheric enhancement ratio of methanol with respect to CO is estimated from the correlation plot between methanol and CO for aged tropical biomass burning plumes. This ratio is in good agreement with the ratio measured in the free troposphere (up to 12 km) by recent aircraft studies and does not suggest any secondary production of methanol by oxidation in aged biomass burning plumes.

Imaging high-energy astrophysical sources using Earth occultation

HIGH-ENERGY astrophysical sources can be difficult to image. Photons with energies above ∼5 keV are hard to focus, so experiments usually employ coded masks1–4 or moving collimators5–9 to modulate the flux received by the detectors; the resulting signals are then deconvolved to form the images. Here we demonstrate a new approach which makes use of the large-area, non-collimated detectors of the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory. As the spacecraft moves in its orbit, the Earth itself acts as a stable occulting disk. Changes in the measured signal during a single occultation correspond to the integrated intensity of sources positioned along the arc described by the Earth's edge (limb). The low-altitude, moderately inclined orbit of the spacecraft ensures that the angle at which the limb traverses a source region varies between occultations, and thus data from a series of occultations can be transformed into an image. This imaging process is conceptually and mathematically similar to those used in fan-beam aperture-synthesis radio-astronomy10 and medical computer-assisted tomography11, and holds great promise for all-sky imaging with relatively simple (and hence inexpensive) detectors.

Management of Carcinoma of the Thyroid

Greater precision has developed in recent decades in the selection of patients for operation for thyroid nodules suspicious for malignancy and in adapting operative procedures to the extent and pathologic variety of the individual thyroid carcinoma, when present. A thyroid lobectomy is considered to be the minimal operative procedure usually indicated for a suspicious thyroid nodule or carcinoma involving one lobe of the thyroid gland. Factors determining the extent of operation for thyroid carcinoma include the pathologic variety, gross distribution of the malignancy, and health status of the individual patient. Total or near total thyroidectomy should be considered for all patients with thyroid carcinoma except for single occult carcinomas and unilateral low grade angio-invasive carcinomas. Removal of lymph nodes in regions adjacent to the thyroid carcinoma is advisable, lateral neck dissections being reserved for patients with palpable lymphadenopathy, demonstrated metastases to lateral cervical lymph nodes, or a poorly differentiated carcinoma likely to metastasize to these lymph nodes. A modified radical lymph node dissection is satisfactory except for those carcinomas invading muscles in the neck. Anatomic neck dissections provide a better prognosis than incomplete lymph node procedures for patients with regional lymph node metastases. Following operation, patients should receive thyroid hormone therapy, be evaluated for possible treatment with radioactive iodine or other therapeutic measures, and be followed for evidence of recurrent disease as well as thyroid and parathyroid function. Adequate early operation is preferred to late ultraradical procedures, from standpoints of morbidity and prognosis. Unfavorable prognostic factors include extensive gross disease, poorly differentiated carcinoma present as the entire lesion or as foci in a differentiated carcinoma, and age over 40. With adequate surgical treatment, the prognosis for operable thyroid carcinoma is good.