Uniform Opacity Research Articles

Gemini/GMOS Transmission Spectral Survey: Complete Optical Transmission Spectrum of the Hot Jupiter WASP-4b

Abstract We present the complete optical transmission spectrum of the hot Jupiter WASP-4b from 440 to 940 nm at R ∼ 400–1500 obtained with the Gemini Multi-Object Spectrometers (GMOS); this is the first result from a comparative exoplanetology survey program of close-in gas giants conducted with GMOS. WASP-4b has an equilibrium temperature of 1700 K and is favorable to study in transmission due to its large scale height (370 km). We derive the transmission spectrum of WASP-4b using four transits observed with the MOS technique. We demonstrate repeatable results across multiple epochs with GMOS, and derive a combined transmission spectrum at a precision about twice above photon noise, which is roughly equal to one atmospheric scale height. The transmission spectrum is well fitted with a uniform opacity as a function of wavelength. The uniform opacity and absence of a Rayleigh slope from molecular hydrogen suggest that the atmosphere is dominated by clouds with condensate grain sizes of ∼1 μm. This result is consistent with previous observations of hot Jupiters since clouds have been seen in planets with similar equilibrium temperatures to WASP-4b. We describe a custom pipeline that we have written to reduce GMOS time-series data of exoplanet transits, and present a thorough analysis of the dominant noise sources in GMOS, which primarily consist of wavelength- and time-dependent displacements of the spectra on the detector, mainly due to a lack of atmospheric dispersion correction.

The centrodistal joint interosseous ligament region in the tarsus of the horse: Normal appearance, abnormalities and possible association with other tarsal lesions, including osteoarthritis.

There have been no detailed descriptions of the radiological appearance of the centrodistal joint interosseous ligament region in horses with and without distal tarsal joint pain. To describe the normal radiological appearance of the centrodistal joint interosseous ligament region; to determine the prevalence of mineralisation or ossification of the interosseous ligament; and to describe radiological abnormalities surrounding the interosseous space and concurrent radiological abnormalities in the tarsus. The association between interosseous ligament region abnormalities and radiological evidence of osteoarthritis of the centrodistal joint was assessed. Retrospective study. Case records and radiographs of all horses/ponies (n=700) that underwent radiographic examination of one/both tarsi over 7years were reviewed. Case history, height, bodyweight and cause(s) of lameness were recorded. Factors associated with abnormalities of the centrodistal interosseous ligament region were assessed using logistic regression analysis. The normal interosseous space was an oval or circular-shaped radiolucent area bordered proximally and distally by a rim of bone of uniform opacity and thickness, which varied in thickness among animals. Abnormalities of the interosseous ligament region of the lame(r) limb were evident in 121/700 (17.3%; 95% confidence interval 14.5-20.1%) animals. Increasing bodyweight was associated with decreased odds of interosseous ligament region abnormalities. Forty-seven animals (6.7%; 95% confidence interval 4.9-8.6%) had radiological evidence of osteoarthritis of the centrodistal joint. A greater proportion of animals with interosseous ligament region abnormalities (36.4%) had radiological evidence of osteoarthritis of the centrodistal joint, compared to those with normal interosseous ligament regions (0.5%; P<0.001). Interosseous ligament region abnormalities and osteoarthritis of the centrodistal joint were not necessarily associated with distal tarsal joint pain. There is an association between abnormalities of the centrodistal joint interosseous ligament region and osteoarthritis. Radiological evidence of abnormalities of the centrodistal intertarsal ligament region alone or in association with osteoarthritis may be present asymptomatically.

Mineralisation or Ossification of the Interosseous Ligament of the Centrodistal Joint of the Horse: Is There an Association with Osteoarthritis?

Reasons for performing studyThere have been no detailed descriptions of the radiological appearance of the centrodistal joint interosseous ligament in horses with and without distal hock joint pain.Objectives1) To describe the normal radiological appearance of the region of the centrodistal joint interosseous ligament; 2) to determine the frequency of occurrence of mineralisation or ossification of the interosseous ligament and to describe radiological abnormalities surrounding the interosseous space; 3) to describe concurrent radiological abnormalities in the tarsus. It was hypothesised that ossification of the interosseous ligament will be associated with radiological evidence of osteoarthritis of the centrodistal joint.Study designSystematic radiological analysis using a predefined grading system, after a repeatability study, and descriptive statistics.MethodsCase records and radiographs of all horses which underwent radiographic examination of one or both tarsi over 7 years were reviewed.ResultsThere were 700 horses, including 470 examined bilaterally. The normal interosseous space was an oval‐shaped radiolucent area surrounded by subchondral bone of uniform opacity and thickness. Changes in the region of the interosseous ligament of the centrodistal joint were evident in 190/1170 (16.2%) tarsi, including 50 horses examined bilaterally. In 33/190 (17.4%) tarsi there was complete loss of the oval‐shaped radiolucent area, together with increased thickness of the adjacent subchondral bone, endosteal irregularity and increased opacity of the adjacent trabecular bone. In addition 157/190 tarsi had patchy increased opacity within the interosseous space and alterations of the adjacent subchondral and trabecular bone. There was radiological evidence of osteoarthritis of the centrodistal joint in 27/33 (81.8%) of tarsi with complete ossification of the centrodistal interosseous ligament, 17 of which (51.5%) had distal tarsal pain, and in 29/157 (18.5%) tarsi with other abnormalities of the centrodistal interosseous ligament.ConclusionsWhen evaluating the tarsus radiologically the region of the centrodistal joint interosseous ligament should be assessed.Ethical animal research: The study was approved by the Ethical Review Committee of the Animal Health Trust and there was informed owner consent. Sources of funding: None. Competing interests: None.

Pleuropulmonary Synovial Sarcoma

Pleuropulmonary synovial sarcoma (PPSS) is increasingly recognized as a subtype of sarcoma because of the recent identification of a distinctive chromosomal translocation specific to synovial sarcoma. Soft-tissue synovial sarcoma is far more common than PPSS and typically develops in para-articular locations of the extremities; affects young and middle-aged adults, with no difference in distribution between the sexes; and has well-documented radiologic manifestations. PPSS may arise in the chest wall, heart, mediastinum, pleura, or lung, and it shares patient demographics and several imaging features with its soft-tissue counterpart. Patients present with a cough, chest pain, or dyspnea. On chest radiographs, PPSS typically appears as a sharply marginated mass with uniform opacity, based either in the pleura or in the lung, and often accompanied by an ipsilateral pleural effusion. Computed tomographic images show a well-circumscribed heterogeneously enhanced lesion without associated involvement of bone and without calcifications (except in the case of a chest wall primary tumor). Magnetic resonance imaging provides superior demonstration of nodular soft tissue and multilocular fluid-filled internal components of PPSS, in addition to peripheral rim enhancement after the intravenous administration of a gadolinium-based contrast material such as gadopentetate dimeglumine. Current treatment consists of surgical resection followed by chemotherapy, radiation therapy, or both.

Hypertrophic osteopathy secondary to pulmonary sarcoma in a cat

A case of hypertrophic osteopathy secondary to a pulmonary spindle cell sarcoma is described. The 9-year-old male cat presented with a 1-month history of decreased appetite, decreased activity and progressive lameness with swelling and pain of all four limbs. Thoracic radiographs showed a soft tissue opaque mass in the left caudal lung lobe. Radiographs of all limbs showed extensive periosteal new bone formation of uniform opacity demonstrating a 'palisading' pattern. The lung mass was removed at exploratory thoracotomy; histopathological examination diagnosed a low-grade spindle cell sarcoma. Prior to surgery, the cat had a non-specific conjunctivitis that resolved spontaneously following lobectomy raising the possibility of a paraneoplastic association. The lameness also resolved; six months after surgery, the periosteal palisading of new bone on the long bones had remodelled, and there was no evidence of pulmonary metastases.

Visual demonstration of the limb-forming zone in the chick embryo lateral plate.

The present study was undertaken to determine whether a visible Wolffian ridge, distinct from the lateral fold, can be identified in chick embryos. Ectoderm thickness was measured in stage 11-17 chick embryos. There was a general trend, from thin ectoderm in the midline, to an ectodermal thickening over the somites, intermediate mesoderm, and lateral plate. Other embryos were cut from the yolk, pinned out, and photographed. The lateral fold was then eliminated, and the embryo was rephotographed. The photographs reveal a definite opaic zone, distinct from the lateral fold, in stage 11-18 chick embryos. Furthermore, there is a direct correlation between the opacity of this cellular band and the limb-forming potential of grafted wing, flank, and leg regions (see Stephens et al., '89). At stages 11-14, the wing, flank, and leg exhibit a uniform opacity, and a uniform capacity for limb formation when grafted to a host celom. From stage 15 to stage 18, the opacity in the flank diminishes, and its limb-forming capability disappears. This study demonstrates the presence of an opaic zone, which we have called the limb-forming zone (LFZ) along the lateral side of early chick embryos, which is independent of the lateral fold, is not as extensive as the lateral plate, and is not simply associated with ectodermal thickening, but which is directly correlated with limb-forming potential in the lateral plate.

A New Silicone Rubber Casting Material Designed for Forensic Science Application

Abstract The need for an improved silicone rubber casting material has been evident for years. Products currently available must usually be coated or colored to make them opaque so that fine detail can be microscopically observed. A new product manufactured in Sweden has properties that make it superior to other casting materials currently available. Visibility of detail in casts made from shallow marks is dramatically increased because of its reflective properties and uniform opacity. Besides the usual tool mark applications, the material has been found useful in the comparison of firing pin impressions where lighting is a problem. It is beneficial in the examination of shiny surfaces such as extractor marks on cartridge casings and on plastic surfaces.

The thalamocortical projection in Pseudemys turtles: a quantitative electron microscopic study.

Thalamic fibers in the cortex of Pseudemys turtles were studied with the electron microscope to determine the type of synaptic vesicle they contain, the type of membrane differentiation they form, and the type of processes they contact. Following unilateral removal of the thalamus, all degenerating thalamic axon terminals are located in the outer third of the molecular layer in the rostral half of general cortex. In the middle of this zone they constitute as much as 25% of all vesicle-containing profiles. The degenerated terminals appear as electron opaque profiles, most commonly with a uniform opacity. They contain round agranular vesicles and form synapses with asymmetrical membrane differentiations. They synapse mainly on dendritic spines containing mitochondria and/or membranous sacs, although some thalamic fibers contact small clear spines, dendrites, and, rarely, cell bodies. Counts show that 86% of degenerated contacts are on dendritic spines and 14% on dendritic shafts. The spines probably all belong to the dendrites of the pyramidal cells, whose somata are located in the deep cellular layer. The dendritic shafts and somata are most likely those of the aspinous stellate neurons located in the molecular layer. Although these stellate cells are not sufficiently numerous to form a cell "layer," each transverse section through thalamic recipient cortex contains about nine of these cells and they occur in a ratio of 1:37 to pyramidal cells in the underlying main cell layer. We have calculated that in a rectangular solid of turtle cortex whose dimensions are 1 mm X 1 mm X the depth from pial surface to the underlying ventricle, there are 5.2 million thalamic fiber contacts (all in the outer 100 micrometers), 15,000 pyramidal neurons in the main cell layer, and 400 stellate cells in the molecular layer. Of the 5.2 million thalamic synapses, 0.7 million contact stellate cells and 4.5 million contact pyramidal cells. Thus each stellate cell in the molecular layer receives on the average 1,800 thalamic fiber contacts, while each pyramidal cell receives only 300 thalamic fiber synapses on the distal portion of its dendrites. The calculations lead to the conclusion that individual stellate cells receive at least six times more thalamic fiber synapses than individual pyramidal cells in turtle cortex. We suggest that the stellate cells in the thalamic input zone are inhibitory and that each thalamic volley not only excites efferent pyramidal cells but is also a powerful activator of inhibitory interneurons.

The less familiar manifestations of schistosomiasis of the urinary tract.

One hundred and fifteen patients with schistosomiasis of the urinary tract were studied. Sixty-five percent of the ureters showed striking deformities, including medial deviation, a straight lumbar course, and in the pelvic segment a bowed appearance with medial and cranial displacement at the vesico-ureteric junction. This appearance, which resembles a "cowhorn", is due to fiborsis the bladder trigone. Stasis and dilation of the upper urinary tract were present in the absence of mechanical obstruction. Strictures were rare (7%), and fluoroscopy during excretory urography confirmed that the changes in the upper urinary tract were due to functional derangement of the ureters and not strictures. Four patterns of bladder calcification are described--the familiar linear rim calcification, an amorphous form, uniform opacity and curvilinear forms. The diagnosis can be suggested from the post-micturition bladder film which shows a coarse, shaggy or polypoid mucosal pattern in all stages of the disease.

Light Curve for Eclipsing Stars with Scattering Envelopes and its Application to the V444 Cygni Binary System

view Abstract Citations (2) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Light Curve for Eclipsing Stars with Scattering Envelopes and its Application to the V444 Cygni Binary System Huang, Su-Shu Abstract The light curve which results from the eclipse of a star by another star with an absorbing envelope of uniform opacity has been computed It has then been applied to the observed light curve of V444 Cygni obtained by Kron and Gordon by assuming that an envelope exists around each of the two component stars. With a suitable choice of parameters, the observed points during secondary eclipse match very well with some computed curve. But no single curve can account for the observed data taken during the primary eclipse. Instead, it appears that they shift from one curve to another in a sequence of curves corresponding to different mean opacities-an indication that the envelope around the `V star has a density gradient that increases downward. This result is consistent with the phenomenon of mass ejection by the W star. The envelope around the 0 star is supposed to be formed out of the ejected matter from the W component in the same way that emission rings in some Algol-type binaries are formed out of the ejecta from the less massive component. This suggestion is further strengthened by the fact that the total optical thickness of the envelope associated with the 0 star is much less than that associated with the W star. Finally, the similarities and differences between this system and Lyr are discussed. Publication: The Astrophysical Journal Pub Date: September 1970 DOI: 10.1086/150605 Bibcode: 1970ApJ...161.1033H full text sources ADS | data products SIMBAD (3)

THE RELATION OF FINENESS OF GRINDING TO OPACITY IN WHITE ENAMELS

The problem of securing a uniform opacity by making observations of smelting, testing of raw materials, etc., led to the conclusion that the most important process was the mill treatment given the mixture. A table showing screen analyses of white enamels is given.