bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of anesthesia with isoflurane on plasma concentrations of adrenocorticotropic hormone in samples obtained from the cavernous sinus and jugular vein of horses
Authors: Carmalt James L. , Duke-Novakovski Tanya , Schott Harold C. , van der Kolk Johannes H.
Published: June 2016

OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses.

ANIMALS 6 clinically normal adult horses.

PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and anesthesia was induced with propofol mixed with ketamine hydrochloride. Horses were positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen and a continuous rate infusion of butorphanol tartrate. One hour after anesthesia was induced, the blood sample protocol was repeated. Plasma ACTH concentrations were quantified by use of a commercially available sandwich assay. Generalized estimating equations that controlled for horse and an expressly automated deconvolution algorithm were used to determine effects of anesthesia on plasma ACTH concentrations and pulsatility, respectively.

RESULTS Anesthesia significantly reduced the plasma ACTH concentration in blood samples collected from the cavernous sinus.

CONCLUSIONS AND CLINICAL RELEVANCE Mean plasma ACTH concentrations in samples collected from the cavernous sinus of anesthetized horses were reduced. Determining the success of partial ablation of the pituitary gland in situ for treatment of pituitary pars intermedia dysfunction may require that effects of anesthesia be included in interpretation of plasma ACTH concentrations in cavernous sinus blood.
Effects of repetition within trials and frequency of trial sessions on quantitative parameters of vertical force peak in horses with naturally occurring lameness
Authors: Kaido Mari , Kilborne Allison H. , Sizemore Joy L. , Reisbig Nathalie A. , Aarnes Turi K. , Bertone Alicia L.
Published: June 2016

OBJECTIVE To analyze the effects of vertical force peak (VFP) of repition within trials and between trial sessions in horses with naturally occurring appendicular lameness.

ANIMALS 20 lame horses acclimated to trotting over a force plate.

PROCEDURES Kinetic gait data were collected by use of a force plate regarding affected and contralateral limbs of lame horses that completed 5 valid repetitions in each of 5 sessions performed at 0, 3, 6, 12, and 24 hours, constituting 1 trial/horse. Data were compared within and among repetitions and sessions, and factors influencing VFP values were identified.

RESULTS VFP values differed for lame limbs after 3 valid repetitions were performed within a session and when the interval between sessions was 3 hours. Direction of change reflected less lameness (greater VFP). Lamer horses (≥ grade 4/5) had this finding to a greater degree than did less lame horses. Results were similar for contralateral limbs regarding valid repetitions within a session; however, VFP decreased when the interval between sessions exceeded 6 hours. The coefficient of variation for VFP was ≤ 8% within sessions and ≤ 6% between sessions. The asymmetry index for VFP did not change throughout the study.

CONCLUSIONS AND CLINICAL RELEVANCE Lameness profiles obtained through kinetic gait analysis of horses with naturally occurring lameness were most accurate when valid repetitions were limited to 3 and the interval between sessions within a trial was > 3 hours. Findings suggested that natural lameness may be as suitable as experimentally induced lameness for lameness research involving horses.
Evaluation of epiduroscopy for detection of vertebral canal and spinal cord lesions in dogs
Authors: Garcia-Pereira Fernando L. , Prange Timo , Seller Aaron , Obert Victoria
Published: June 2016

OBJECTIVE To evaluate the potential usefulness of epiduroscopy for clinical diagnosis and treatment of vertebral canal and spinal cord lesions in dogs.

SAMPLE Cadavers of 6 mixed-breed dogs.

PROCEDURES Dogs were positioned in sternal recumbency, and an endoscope was introduced into the lumbosacral epidural space. A fiberscope (diameter, 0.9 mm; length, 30 cm) was used for 3 dogs, and a videoscope (diameter, 2.8 mm; length, 70 cm) was used for the other 3 dogs. Visibility and identities of anatomic structures were recorded, and maneuverability of the endoscopes was assessed. Extent of macroscopic tissue damage was evaluated by manual dissection of the vertebral canal at the end of the procedure.

RESULTS Intermittent saline (0.9% NaCl) solution infusion, CO2 insufflation, and endoscope navigation improved visualization by separating the epidural fat from the anatomic structures of interest. Images obtained with the fiberscope were small and of poor quality, making identification of specific structures difficult. Maneuverability of the fiberscope was difficult, and target structures could not be reliably reached or identified. Maneuverability and image quality of the videoscope were superior, and spinal nerve roots, spinal dura mater, epidural fat, and blood vessels could be identified. Subsequent manual dissection of the vertebral canal revealed no gross damage in the spinal cord, nerve roots, or blood vessels.

CONCLUSIONS AND CLINICAL RELEVANCE A 2.8-mm videoscope was successfully used to perform epiduroscopy through the lumbosacral space in canine cadavers. Additional refinement and evaluation of the technique in live dogs is necessary before its use can be recommended for clinical situations.
Temporary percutaneous T-fastener gastropexy and continuous decompressive gastrostomy in dogs with experimentally induced gastric dilatation
Authors: Fox-Alvarez W. Alexander , Case J. Brad , Cooke Kirsten L. , Garcia-Pereira Fernando L. , Buckley Gareth J. , Monnet Eric , Toskich Beau B.
Published: June 2016

OBJECTIVE To evaluate a percutaneous, continuous gastric decompression technique for dogs involving a temporary T-fastener gastropexy and self-retaining decompression catheter.

ANIMALS 6 healthy male large-breed dogs.

PROCEDURES Dogs were anesthetized and positioned in dorsal recumbency with slight left-lateral obliquity. The gastric lumen was insufflated endoscopically until tympany was evident. Three T-fasteners were placed percutaneously into the gastric lumen via the right lateral aspect of the abdomen, caudal to the 13th rib and lateral to the rectus abdominis muscle. Through the center of the T-fasteners, a 5F locking pigtail catheter was inserted into the gastric lumen and attached to a device measuring gas outflow and intragastric pressure. The stomach was insufflated to 23 mm Hg, air was allowed to passively drain from the catheter until intraluminal pressure reached 5 mm Hg for 3 cycles, and the catheter was removed. Dogs were hospitalized and monitored for 72 hours.

RESULTS Mean ± SD catheter placement time was 3.3 ± 0.5 minutes. Mean intervals from catheter placement to a ≥ 50% decrease in intragastric pressure and to ≤ 6 mm Hg were 2.1 ± 1.3 minutes and 8.4 ± 5.1 minutes, respectively. After catheter removal, no gas or fluid leakage at the catheter site was visible laparoscopically or endoscopically. All dogs were clinically normal 72 hours after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE The described technique was performed rapidly and provided continuous gastric decompression with no evidence of postoperative leakage in healthy dogs. Investigation is warranted to evaluate its effectiveness in dogs with gastric dilatation-volvulus.
Critical care of patients with cancer
Authors: Shimabukuro‐Vornhagen Alexander , Böll Boris , Kochanek Matthias , Azoulay Éli , von Bergwelt‐Baildon Michael S.
Published: June 2016

Answer questions and earn CME/CNE

The increasing prevalence of patients living with cancer in conjunction with the rapid progress in cancer therapy will lead to a growing number of patients with cancer who will require intensive care treatment. Fortunately, the development of more effective oncologic therapies, advances in critical care, and improvements in patient selection have led to an increased survival of critically ill patients with cancer. As a consequence, critical care has become an important cornerstone in the continuum of modern cancer care. Although, in many aspects, critical care for patients with cancer does not differ from intensive care for other seriously ill patients, there are several challenging issues that are unique to this patient population and require special knowledge and skills. The optimal management of critically ill patients with cancer necessitates expertise in oncology, critical care, and palliative medicine. Cancer specialists therefore have to be familiar with key principles of intensive care for critically ill patients with cancer. This review provides an overview of the state‐of‐the‐art in the individualized management of critically ill patients with cancer. CA Cancer J Clin 2016;66:496–517. © 2016 American Cancer Society.
Relation of Pancreatic Enzymes and Serum Transaminases Levels with Modified CT Severity Index In Acute Pancreatitis
Authors: Sharif Md Mofazzal , Rahman Md Towhidur , Ferdousi Mahfuz Ara , Taher Md Abu , Shegufta Farzana , Azam Golam
Published: June 2016

Introduction: Diagnosis of patients with severe acute pancreatitis as soon as possible is critical for achieving optimal outcomes. Management depends largely on severity. Medical treatment of mild acute pancreatitis is relatively straightforward. Treatment of severe acute pancreatitis involves intensive care. Surgical intervention (open or minimally invasive) is indicated in selected cases.Methodology: A total number of 59 subjects were enrolled in this present prospective study in the department of Radiology and Imaging, BIRDEM during two years aim to find out the correlation between CT severity index and patient serum enzyme levels in acute pancreatitis. Patients with clinically suspected and biochemically diagnosed acute pancreatitis referred to Radiology and Imaging department from department of gastroenterology (GHPD), BIRDEM for imaging investigation were enrolled in this study. Severity of acute pancreatitis was measured by both clinical and imaging staging (Modified CT severity index) in mild, moderate and severe groups. Subjects clinical informations and serum enzymes were recorded and analyzed by computer software SPSS (Ver. 20-IBM).Result: Mean age of the study subjects was 36.43 ± 13.85 years. The age ranged from 20-63 years and the maximum number was found in 21 to 40 years age group. Male female ratio was almost 1.56:1. It was seen that diffuse pancreatic enlargement was noted in 20.33% subjects. Pancreatic inflammation with and without peripancreatic fat involvement were observed in 22.72% and 57.62% subjects respectively. Pseudocyst formation (11.86%), ascites (23.72%), renal fascia involvement (37.28%) and pleural effusion (30.5%) were seen in CT scan. The results of the interpreter analysis was Kappa = 0.852 with p < 0.001 when association of severity by clinical scoring and CT severity scoring was compared and revealed that measure of agreement, while statistically significant, was almost perfect agreement. CT severity index in acute pancreatitis had statistically significant (p is less than 0.05) relation with serum amylase (0.738), lipase (0.638), SGOT (0.581) and SGPT (0.365) during admission which was found on simple linear regression test.Conclusion: This present study concluded that modified CT severity index correlated well with patients enzymes level (Amylase, lipase, SGOT, SGPT) as well as clinical findings in acute pancreatitisBirdem Med J 2015; 5(1) Supplement: 18-24
Characterization of Nanoemulsion Prepared from Self-emulsifying Rifampicin and its Antibacterial Effect on Staphylococcus aureus and Stap. epidermidis Isolated from Acne
Authors: Begum Kohinur , Sarker Amit , Shimu Israt Jahan , Chowdhury Md Mazharul Islam , Jalil Reza Ul
Published: June 2016

In this study, three different self emulsifying drug delivery systems of rifampicin (SEDD-R) were made using oleic acid and different surfactants such as Tween 80, Chremophor RH 40 and Chremophor EL designated as RN-TW, RN-CRH and RN- CEL. These self-emulsifying systems were converted to rifampicin nanoemulsion by adding water under sonication. The resulting particle sizes were found to be 192.7 nm, 183.4 nm and 179.2 nm for RN- CEL, RN-CRH and RN-TW, respectively using Zetasizer. Drug content, entrapment efficiency, in vitro drug release and pH stability tests was performed. Drug content and entrapment efficiency for RNTW, RN-CRH and RN- CEL were found as 0.9945% & 0.9835%, 0.9720% & 84.31% and 74.58 % & 56.89%, respectively. The release of drug from RN-TW, RN-CRH and RN-CEL occurred for 450-, 330- and 240- minutes, respectively. The pH stability study demonstrated that all formulations retained maximum drug at pH 5.8. Antibacterial effect of the preparations was evaluated against S. epidermidis and S. aureus isolated from acne and showed effective results.Dhaka Univ. J. Pharm. Sci. 14(2): 171-177, 2015 (December)
Prostate Cancer Risk in Relation to CYP3A4 and CYP3A5 Genotypes in the Bangladeshi Population
Authors: Bellah Sm Faysal , Ahmed Maizbha Uddin , Rabbi Sikder Nahidul Islam , Apu Mohd Nazmul Hasan , Islam Md Siddiqul , Uddin Mir Muhammad Nasir , Islam Mohammad Safiqul , Hasnat Abul
Published: June 2016

Genetic polymorphism on CYP3A4 and CYP3A5 gene and their associational susceptibility to prostate cancer was studied on Bangladeshi population, considering the importance of CYP3A4 and CYP3A5 gene in detoxification of xenobiotics from physiological territory. In this case control regulated study, we focused on two allelic variants CYP3A4 rs2740574 (CYP3A4*1B) and CYP3A5 rs776746 (CYP3A5*3) applying Polymerase Chain Reaction (PCR)-Restriction Fragment Length Polymorphism (RFLP). Associational risk on prostate cancer was estimated as odds ratio (OR) and 95% confidence interval (CI) using unconditional logistic regression models. An elevated prostate cancer risk was found with heterozygous, mutant and heterozygous plus mutant variants of CYP3A4*1B which is not statistically significant (p>0.05), whereas a significant association was found with heterozygous, mutant and heterozygous plus mutant variants of CYP3A5*3 (OR =4.36, 95%CI = 1.53 to 12.38, P =0.003; OR =3.85, 95%CI = 1.19 to 12.43, P = 0.017 and OR =4.13, 95%CI = 1.84 to 9.28, p =0.0006 respectively). The findings signposted a significant association of CYP3A5*3 gene and nullify the association of CYP3A4*1B genes polymorphism with prostate cancer risk in Bangladeshi subject.Dhaka Univ. J. Pharm. Sci. 14(2): 179-185, 2015 (December)
Development and Evaluation of Indomethacin Controlled Release Press Coated Tablets
Authors: Islam Muhammad Rashedul , Mamun Md Elias Al , Moghal Md Mizanur Rahman , Rahman Md Habibur
Published: June 2016

In the present work, several batches of indomethacin press coated tablets were prepared with drug and Avicel PH 102 utilizing the press coating technology. The core tablet was compression coated with minimal compression pressure. The compression coating mixture was formulated using various amount of lactose and xanthan gum which was used as the release retarding agent. Three formulations (IX-1, IX-2 and IX-3) were designed to evaluate the release profile as function of xanthan gum load. In vitro drug release testing demonstrated that the drug release was inversely proportional to the amount of xanthan gum in the coating formulations. In addition, formulation IX-2 was modified by incorporating hydroxypropyl methyl cellulose (HPMC) 15 cps into the compression coating formulation to understand their effects on drug release. The formulation was evaluated for its properties and correlated with in vitro and kinetic release studies. Incorporation of HPMC caused the highest fraction of drug to be released in the dissolution fluid. The physico-chemical properties of the excipients can be held responsible for the discrepancy in release rate of indomethacin. From kinetic analysis drug release was found to follow Higuchi mechanism for all the formulations. Overall, the study concluded that excipients present in the coating formulations make a significant impact on drug release.Dhaka Univ. J. Pharm. Sci. 14(2): 187-192, 2015 (December)
Antimicrobial, Thrombolytic, Membrane Stabilizing Activities and Total Flavonoid Content of Various Partitionates of Aerial Parts of Eclipta alba (L.) Hassk
Authors: Uddin Jalal , Julie Azima Sultana , Ali Md Haider , Islam Md Nurul , Khan Shah Alam , Labu Zubair Khalid
Published: June 2016

Eclipta alba is a medicinal herb belonging to the family of Asteraceae. Locally it is known as Kalokeshi and has a history of ethno-medicinal properties. The crude ethanolic extract of E. alba leaves was partitioned successively by solvents of different polarities. The crude extract along with different partitionates was evaluated for their possible antimicrobial, thrombolytic and membrane stabilizing activities. In this study, n-hexane soluble fraction (HXSF) showed 55.56% maximum activity against thrombosis in comparison with streptokinase (SK) 62.67%. For hypotonic solution- and heat-induced conditions, the n-hexane soluble fractionate (67.35 ± 0.50%) significantly inhibited the haemolysis of HRBCs by 67.35 ± 0.50% and 62.12 ± 0.69%, respectively as compared to the standard acetyl salicylic acid (77.91 ± 0.29%). The ethanol extract of the plant showed higher inhibitory action against Staphylococcus aureus, Bacillus subtilis, Proteus mirabilis and Pseudomonas fluroescens. The total flavonoid content was quite significant in ethanolic extract (142.17 ± 0.15 mg/g). Hence, the results of the present study revealed that the leaves of this traditional medicinal plant are a remedy for thrombosis, red blood cell membrane stabilization and microbial infections against some human pathogens.Dhaka Univ. J. Pharm. Sci. 14(2): 207-213, 2015 (December)
Effects of Different Boundary Conditions at the Surfaces of the Extended Computational Domain in Computing the Natural Convection Flow in an Open Cavity
Authors: Begum Roushanara , Bangalee MZI
Published: June 2016

Effects of different boundary conditions at the surfaces of the extended computational domain on buoyancy driven natural convection flow in a three dimensional open cavity are studied numerically. This study is carried out for turbulent flow where Rayleigh number is greater than 108. Air is used as working fluid having properties at 25°C temperature and 1atm pressure. To capture the turbulent nature of the flow k - ? model is used. ANSYS CFX software is used to solve the governing equations subject to the corresponding boundary conditions. The methodology is verified through a satisfactory comparison with some published results. Average mass flow, temperature, stream line, contour velocity and velocity profile are studied at different height. An extended computational domain around the physical domain of the cavity at different surrounding conditions is considered to investigate the effect of its existence on the computation. Effects of different surrounding boundary conditions on the physical domain of the cavity are studied and reported.A relation among non-dimensional parameters such as Nusselt number, Rayleigh number, Prandlt number and Reynolds number is also reported.Dhaka Univ. J. Sci. 64(1): 31-37, 2016 (January)
Radiation Effect on Unsteady Mixed Convection Boundary Layer Flow, Heat and Mass Transfer over a Wedge
Authors: Roy NC , Firoza MN , Halder AK
Published: June 2016

This paper concerns the unsteady mixed convection laminar boundary layer flow past a vertical wedge in the presence of thermal radiation. The governing equations have been solved by the straightforward finite difference method for the entire frequency range. We observe that the Richardsons number, Ri, strongly affects the skin friction, heat transfer and mass transfer. The effect of the Schmidt number, Sc, on the mass transfer is significant, whereas the skin friction and the heat transfer are almost unaffected by it. Also the heat transfer is considerably dependent on the conduction-radiation parameter, Rd, but the influence of this parameter on the skin friction and the mass transfer is rather weak.Dhaka Univ. J. Sci. 64(1): 59-64, 2016 (January)
Exact Traveling Wave Solutions of Modified Liouville Equation
Authors: Salam Md Abdus , Obayedullah Md , Ali Md Shajib
Published: June 2016

In this paper fuzzy version of secant method has been introduced to obtain approximate solutions of a fuzzy non-linear equation. Graphical representations of the approximate solutions have also been shown. The idea of converging to the root to the desired degree of accuracy, which is the optimum solution, of a fuzzy non-linear equation has been focused.GANIT J. Bangladesh Math. Soc.Vol. 35 (2015) 135-143
Double Signature
Authors: Hanrahan Mairéad
Published: June 2016

This article discusses Glas in the light of Derrida's notion of the countersignature as both affirmation and betrayal of the countersigned. It explores how the two columns of Glas confirm as well as oppose each other, notably in relation to sexual difference, and examines how Derrida in turn is both faithful and unfaithful towards Hegel and Genet. Tracing the complexity of Derrida's signature, it reflects on its broader implications for his deconstructive project.
From Deconstruction to Disaster (Derrida, Blanchot, Hegel)
Authors: Hill Leslie
Published: June 2016

Derrida's Glas (1974) found one of its most attentive readers in Maurice Blanchot, whose fragmentary volume L'Ecriture du désastre (The Writing of the Disaster) (1980) responds in a number of ways to Derrida's book, in particular to its reading of Hegel. This article retraces the silent dialogue between Derrida and Blanchot as it unfolds in the two texts mentioned as well as in several others, including some of Blanchot's earlier essays and fiction, notably La Folie du jour (The Madness of the Day) and L'Arrêt de mort (Death Sentence).
Does Antigone Stand or Fall in Relation to Hegel's Master–Slave dialectic? A Response to Derrida's Glas
Authors: Chanter Tina
Published: June 2016

In Glas, Derrida focuses his attention on a question regarding the family, on the unintelligibility of familial love for which Hegel makes Antigone representative. The account of the emergence of self-consciousness in the family differs in several crucial ways from the standard account of how Hegelian self-consciousness is constituted in the master–slave dialectic. Most notably, the achievement of self-consciousness through familial love involves no risk of life, no struggle to the death, no conflict. While Derrida refrains from interrogating the relation between the master–slave dialectic and sexual difference directly, he interrogates the peaceful recognition that Hegel says occurs between Polynices as brother and Antigone as sister. I explore the silences that punctuate Derrida's discussion of Antigone, especially his silence on Hegel's twofold elision of the master–slave dialectic with the husband–wife relation, and of Antigone with the figure of the wife. By symbolically marrying her off, Hegel subordinates Antigone to a symbolic husband.
Philosophy in Erection
Authors: Malabou Catherine
Published: June 2016

Dialectics operates, Derrida writes, ‘in raising or erecting what falls’. Yet the Hegelian system is problematized in the sense that, in the Genet column of Glas, what substitutes for the system is not a well-grounded philosophical alternative, but a sort of disseminal substitution itself, working within as much as against the system it resists. The confrontation staged by the text is not between homosexual transgression, on the one hand, and heterosexual normativity as the origin of the social bond, on the other, but instead a confrontation between two perspectives on the transcendental. The problem of Glas is that the two columns seem to ‘come out the same’ (in French ‘revenir au même’, amounting to the same) at the very moment when they seem to radically differ or diverge. Put differently, this problem is that of a contagion between the two sides. Why is there a risk of contagion and of similarity? What does this do to the transcendentality in question?
Notes towards a Discussion of Method and Metaphor in Glas
Authors: Bennington Geoffrey
Published: June 2016

At several moments Glas proposes what it is hard not to see as methodological comments on its own procedure. These comments are usually quite difficult, and often involve dense figurative characterizations of the way the work proceeds, always folding any apparent metalinguistic position back on to the object text. After detailed discussion of several of these moments, a second section examines Derrida's deconstruction of Hegel's account of metaphor, and suggests it entails a non-teleological thinking of life. In all these cases, it is suggested that Derrida is consistently showing up an instability of the ‘meta-’ in general, even in apparently meta-physical texts.
NPI-Licensing and Focus Movement
Authors: Wagner Michael
Published: June 2016

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SHOCK CONNECTIVITY IN THE 2010 AUGUST AND 2012 JULY SOLAR ENERGETIC PARTICLE EVENTS INFERRED FROM OBSERVATIONS AND ENLIL MODELING
Authors: Bain H. M. , Mays M. L. , Luhmann J. G. , Li Y. , Jian L. K. , Odstrcil D.
Published: June 2016

During periods of increased solar activity, coronal mass ejections (CMEs) can occur in close succession and proximity to one another. This can lead to the interaction and merger of CME ejecta as they propagate in the heliosphere. The particles accelerated in these shocks can result in complex solar energetic particle (SEP) events, as observing spacecraft form both remote and local shock connections. It can be challenging to understand these complex SEP events from in situ profiles alone. Multipoint observations of CMEs in the near-Sun environment, from the Solar Terrestrial Relations Observatory–Sun Earth Connection Coronal and Heliospheric Investigation and the Solar and Heliospheric Observatory Large Angle and Spectrometric Coronagraph, greatly improve our chances of identifying the origin of these accelerated particles. However, contextual information on conditions in the heliosphere, including the background solar wind conditions and shock structures, is essential for understanding SEP properties well enough to forecast their characteristics. Wang–Sheeley–Arge WSA-ENLIL + Cone modeling provides a tool to interpret major SEP event periods in the context of a realistic heliospheric model and to determine how much of what is observed in large SEP events depends on nonlocal magnetic connections to shock sources. We discuss observations of the SEP-rich periods of 2010 August and 2012 July in conjunction with ENLIL modeling. We find that much SEP activity can only be understood in the light of such models, and in particular from knowing about both remote and local shock source connections. These results must be folded into the investigations of the physics underlying the longitudinal extent of SEP events, and the source connection versus diffusion pictures of interpretations of SEP events.
PARALLAX OF GALACTIC CEPHEIDS FROM SPATIALLY SCANNING THE WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE: THE CASE OF SS CANIS MAJORIS
Authors: Casertano Stefano , Riess Adam G. , Anderson Jay , Anderson Richard I. , Bowers J. Bradley , Clubb Kelsey I. , Cukierman Aviv R. , Filippenko Alexei V. , Graham Melissa L. , MacKenty John W. , Melis Carl , Tucker Brad E. , Upadhya Gautam
Published: June 2016

We present a high-precision measurement of the parallax for the 12-day Cepheid SS Canis Majoris, obtained via spatial scanning with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). Spatial scanning enables astrometric measurements with a precision of 20–40 μas, an order of magnitude better than pointed observations. SS CMa is the second Cepheid targeted for parallax measurement with HST and is the first of a sample of 18 long-period (≳10 days) Cepheids selected in order to improve the calibration of their period–luminosity relation and eventually permit a determination of the Hubble constant H
0 to better than 2%. The parallax of SS CMa is found to be 348 ± 38 μas, corresponding to a distance of 2.9 ± 0.3 kpc. We also present a refinement of the static geometric distortion of WFC3 obtained using spatial scanning observations of calibration fields, with a typical magnitude ≲0.01 pixels on scales of 100 pixels.
CONTROVERSY OF THE GRO J1655-40 BLACK HOLE MASS AND SPIN ESTIMATES AND ITS POSSIBLE SOLUTIONS
Authors: Stuchlík Z. , Kološ M.
Published: June 2016

Estimates of the black hole mass M and the dimensionless spin a in the microquasar GRO J1655-40 implied by strong gravity effects related to the timing and spectral measurements are controversial, if the mass restriction determined by the dynamics related to independent optical measurements, M
opt = (5.4 ± 0.3) M
⊙, is applied. The timing measurements of twin high-frequency (HF) quasiperiodic oscillations (QPOs) with the frequency ratio 3:2 and the simultaneously observed low-frequency (LF) QPO imply spin in the range

if models based on the frequencies of geodesic epicyclic motion are used to fit the timing measurements, and the correlated creation of the twin HF QPOs and the LF QPO at a common radius is assumed. On the other hand, the spectral continuum method implies

, and the Fe-line-profile method implies

. This controversy can be cured if we abandon the assumption of the occurrence of the twin HF QPOs and the simultaneously observed LF QPO at a common radius. We demonstrate that the epicyclic resonance model of the twin HF QPOs is able to predict the spin in agreement with the Fe-profile method, but no model based on the geodesic epicyclic frequencies can be in agreement with the spectral continuum method. We also show that the non-geodesic string loop oscillation model of twin HF QPOs predicts spin a > 0.3 under the optical measurement limit on the black hole mass, which is in agreement with both the spectral continuum and Fe-profile methods.
SHEAR-DRIVEN DYNAMO WAVES IN THE FULLY NONLINEAR REGIME
Authors: Pongkitiwanichakul P. , Nigro G. , Cattaneo F. , Tobias S. M.
Published: June 2016

Large-scale dynamo action is well understood when the magnetic Reynolds number (Rm) is small, but becomes problematic in the astrophysically relevant large Rm limit since the fluctuations may control the operation of the dynamo, obscuring the large-scale behavior. Recent works by Tobias & Cattaneo demonstrated numerically the existence of large-scale dynamo action in the form of dynamo waves driven by strongly helical turbulence and shear. Their calculations were carried out in the kinematic regime in which the back-reaction of the Lorentz force on the flow is neglected. Here, we have undertaken a systematic extension of their work to the fully nonlinear regime. Helical turbulence and large-scale shear are produced self-consistently by prescribing body forces that, in the kinematic regime, drive flows that resemble the original velocity used by Tobias & Cattaneo. We have found four different solution types in the nonlinear regime for various ratios of the fluctuating velocity to the shear and Reynolds numbers. Some of the solutions are in the form of propagating waves. Some solutions show large-scale helical magnetic structure. Both waves and structures are permanent only when the kinetic helicity is non-zero on average.
STELLAR YIELDS FROM METAL-RICH ASYMPTOTIC GIANT BRANCH MODELS
Authors: Karakas Amanda I. , Lugaro Maria
Published: June 2016

We present new theoretical stellar yields and surface abundances for three grids of metal-rich asymptotic giant branch (AGB) models. Post-processing nucleosynthesis results are presented for stellar models with initial masses between 1 M
☉ and 7.5 M
☉ for Z = 0.007, and 1 M
☉ and 8 M
☉ for Z = 0.014 (solar) and Z = 0.03. We include stellar surface abundances as a function of thermal pulse on the AGB for elements from C to Bi and for a selection of isotopic ratios for elements up to Fe and Ni (e.g.,

/

), which can be obtained from observations of molecules in stars and from the laboratory analysis of meteoritic stardust grains. Ratios of elemental abundances of He/H, C/O, and N/O are also included, which are useful for direct comparison to observations of AGB stars and their progeny, including planetary nebulae. The integrated elemental stellar yields are presented for each model in the grid for hydrogen, helium, and all stable elements from C to Bi. Yields of Li are also included for intermediate-mass models with hot bottom burning. We present the first slow neutron-capture (s-process) yields for super solar metallicity AGB stars with Z = 0.03, and the first complete s-process yields for models more massive than 6 M
☉ at all three metallicities.
SUPER-EARTH ATMOSPHERES: SELF-CONSISTENT GAS ACCRETION AND RETENTION
Authors: Ginzburg Sivan , Schlichting Hilke E. , Sari Re’em
Published: June 2016

Some recently discovered short-period Earth- to Neptune-sized exoplanets (super-Earths) have low observed mean densities that can only be explained by voluminous gaseous atmospheres. Here, we study the conditions allowing the accretion and retention of such atmospheres. We self-consistently couple the nebular gas accretion onto rocky cores and the subsequent evolution of gas envelopes following the dispersal of the protoplanetary disk. Specifically, we address mass-loss due to both photo-evaporation and cooling of the planet. We find that planets shed their outer layers (dozens of percent in mass) following the disk's dispersal (even without photo-evaporation), and their atmospheres shrink in a few Myr to a thickness comparable to the radius of the underlying rocky core. At this stage, atmospheres containing less particles than the core (equivalently, lighter than a few percent of the planet's mass) can be blown away by heat coming from the cooling core, while heavier atmospheres cool and contract on a timescale of Gyr at most. By relating the mass-loss timescale to the accretion time, we analytically identify a Goldilocks region in the mass-temperature plane in which low-density super-Earths can be found: planets have to be massive and cold enough to accrete and retain their atmospheres, but not too massive or cold, such that they do not enter runaway accretion and become gas giants (Jupiters). We compare our results to the observed super-Earth population and find that low-density planets are indeed concentrated in the theoretically allowed region. Our analytical and intuitive model can be used to investigate possible super-Earth formation scenarios.
THE EXTENDED STELLAR COMPONENT OF GALAXIES THE NATURE OF DARK MATTER
Authors: Power C. , Robotham A. S. G.
Published: June 2016

Deep observations of galaxies reveal faint extended stellar components (hereafter ESCs) of streams, shells, and halos. These are a natural prediction of hierarchical galaxy formation, as accreted satellite galaxies are tidally disrupted by their host. We investigate whether or not global properties of the ESC could be used to test of dark matter, reasoning that they should be sensitive to the abundance of low-mass satellites, and therefore the underlying dark matter model. Using cosmological simulations of galaxy formation in the favored Cold Dark Matter (CDM) and Warm Dark Matter (WDM) models (

), which suppress the abundance of low-mass satellites, we find that the kinematics and orbital structure of the ESC is consistent across models. However, we find striking differences in its spatial structure, as anticipated—a factor of ∼10 drop in spherically averaged mass density between ∼10% and ∼75% of the virial radius in the more extreme WDM runs (

 = 0.5, 1

) relative to the CDM run. These differences are consistent with the mass assembly histories of the different components, and are present across redshifts. However, even the least discrepant of the WDM models is incompatible with current observational limits on

. Importantly, the differences we observe when varying the underlying dark matter are comparable to the galaxy-to-galaxy variation we expect within a fixed dark matter model. This suggests that it will be challenging to place limits on dark matter using only the unresolved spatial structure of the the ESC.
THE NATURE OF CME-FLARE-ASSOCIATED CORONAL DIMMING
Authors: Cheng J. X. , Qiu J.
Published: June 2016

Coronal mass ejections (CMEs) are often accompanied by coronal dimming that is evident in extreme ultraviolet (EUV) and soft X-ray observations. The locations of dimming are sometimes considered to map footpoints of the erupting flux rope. As the emitting material expands in the corona, the decreased plasma density leads to reduced emission observed in spectral and irradiance measurements. Therefore, signatures of dimming may reflect the properties of CMEs in the early phase of their eruption. In this study, we analyze the event of flare, CME, and coronal dimming on 2011 December 26. We use the data from the Atmospheric Imaging Assembly on the Solar Dynamics Observatory for disk observations of the dimming, and analyze images taken by EUVI, COR1, and COR2 on board the Solar Terrestrial Relations Observatory to obtain the height and velocity of the associated CMEs observed at the limb. We also measure the magnetic reconnection rate from flare observations. Dimming occurs in a few locations next to the flare ribbons, and it is observed in multiple EUV passbands. Rapid dimming starts after the onset of fast reconnection and CME acceleration, and its evolution tracks the CME height and flare reconnection. The spatial distribution of dimming exhibits cores of deep dimming with a rapid growth, and their light curves are approximately linearly scaled with the CME height profile. From the dimming analysis we infer the process of the CME expansion, and estimate properties of the CME.
GAMMA-RAY BURST REVERSE SHOCK EMISSION IN EARLY RADIO AFTERGLOWS
Authors: Resmi Lekshmi , Zhang Bing
Published: June 2016

Reverse shock (RS) emission from gamma-ray bursts is an important tool in investigating the nature of the ejecta from the central engine. If the magnetization of the ejecta is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would provide an important contribution to early afterglow light curve. In the radio band, synchrotron self-absorption may suppress early RS emission and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band under different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both RSs and forward shocks (FSs). We calculate the ratio between the RS to FS flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS emission which is enhanced by moderate magnetization, moderately magnetized ejecta do not necessarily produce a brighter radio RS due to the self-absorption effect. For typical parameters, the RS emission component would not be detectable below 1 GHz unless the medium density is very low (e.g., n < 10−3 cm−3 for the interstellar medium and A
* < 5 × 10−4 for wind). These predictions can be tested using the afterglow observations from current and upcoming radio facilities such as the Karl G. Jansky Very Large Array, the Low-Frequency Array, the Five Hundred Meter Aperture Spherical Telescope, and the Square Kilometer Array.
THE EVOLUTION OF THE GALAXY STELLAR MASS FUNCTION AT z = 4–8: A STEEPENING LOW-MASS-END SLOPE WITH INCREASING REDSHIFT
Authors: Song Mimi , Finkelstein Steven L. , Ashby Matthew L. N. , Grazian A. , Lu Yu , Papovich Casey , Salmon Brett , Somerville Rachel S. , Dickinson Mark , Duncan K. , Faber Sandy M. , Fazio Giovanni G. , Ferguson Henry C. , Fontana Adriano , Guo Yicheng , Hathi Nimish , Lee Seong-Kook , Merlin Emiliano , Willner S. P.
Published: June 2016

We present galaxy stellar mass functions (GSMFs) at z = 4–8 from a rest-frame ultraviolet (UV) selected sample of ∼4500 galaxies, found via photometric redshifts over an area of ∼280 arcmin2 in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)/Great Observatories Origins Deep Survey (GOODS) fields and the Hubble Ultra Deep Field. The deepest Spitzer/IRAC data to date and the relatively large volume allow us to place a better constraint at both the low- and high-mass ends of the GSMFs compared to previous space-based studies from pre-CANDELS observations. Supplemented by a stacking analysis, we find a linear correlation between the rest-frame UV absolute magnitude at 1500 Å (

) and logarithmic stellar mass (

) that holds for galaxies with

. We use simulations to validate our method of measuring the slope of the

–M
UV relation, finding that the bias is minimized with a hybrid technique combining photometry of individual bright galaxies with stacked photometry for faint galaxies. The resultant measured slopes do not significantly evolve over z = 4–8, while the normalization of the trend exhibits a weak evolution toward lower masses at higher redshift. We combine the

–M
UV distribution with observed rest-frame UV luminosity functions at each redshift to derive the GSMFs, finding that the low-mass-end slope becomes steeper with increasing redshift from

at z = 4 to

at z = 8. The inferred stellar mass density, when integrated over

–1013
M
⊙, increases by a factor of

between z = 7 and z = 4 and is in good agreement with the time integral of the cosmic star formation rate density.
A MID-INFRARED VIEW OF THE HIGH MASS STAR FORMATION REGION W51A
Authors: Barbosa C. L. , Blum R. D. , Damineli A. , Conti P. S. , Gusmão D. M.
Published: June 2016

In this paper we present the results of a mid-infrared study of G49.5-0.4, or W51A, part of the massive starbirth complex W51. Combining public data from the Spitzer IRAC camera, and Gemini mid-infrared camera T-ReCS at 7.73, 9.69, 12.33, and 24.56 μm, with a spatial resolution of ∼0.″5, we have identified the mid-infrared counterparts of eight ultracompact H ii regions, showing that two radio sources are deeply embedded in molecular clouds and another is a cloud of ionized gas. From the T-ReCS data we have unveiled the central core of the W51 region, revealing massive young stellar candidates. We modeled the spectral energy distribution of the detected sources. The results suggest that the embedded objects are sources with spectral types ranging from B3 to O5, but the majority of the fits indicate stellar objects with B1 spectral types. We also present an extinction map of IRS 2, showing that a region with lower extinction corresponds to the region where a proposed jet of gas has impacted the foreground cloud. From this map, we also derived the total extinction toward the enigmatic source IRS 2E, which amounts to ∼60 mag in the V band. We calculated the color temperature due to thermal emission of the circumstellar dust of the detected sources; the temperatures are in the interval of ∼100–150 K, which corresponds to the emission of dust located at 0.1 pc from the central source. Finally, we show a possible mid-infrared counterpart of a detected source at millimeter wavelengths that was found by Zapata et al. to be a massive young stellar object undergoing a high accretion rate.
USING LEAKED POWER TO MEASURE INTRINSIC AGN POWER SPECTRA OF RED-NOISE TIME SERIES
Authors: Zhu S. F. , Xue Y. Q.
Published: June 2016

Fluxes emitted at different wavebands from active galactic nuclei (AGNs) fluctuate at both long and short timescales. The variation can typically be characterized by a broadband power spectrum, which exhibits a red-noise process at high frequencies. The standard method of estimating the power spectral density (PSD) of AGN variability is easily affected by systematic biases such as red-noise leakage and aliasing, in particular when the observation spans a relatively short period and is gapped. Focusing on the high-frequency PSD that is strongly distorted due to red-noise leakage and usually not significantly affected by aliasing, we develop a novel and observable normalized leakage spectrum (NLS), which sensitively describes the effects of leaked red-noise power on the PSD at different temporal frequencies. Using Monte Carlo simulations, we demonstrate how an AGN underlying PSD sensitively determines the NLS when there is severe red-noise leakage, and thereby how the NLS can be used to effectively constrain the underlying PSD.
KINETIC SIMULATION OF SLOW MAGNETOSONIC WAVES AND QUASI-PERIODIC UPFLOWS IN THE SOLAR CORONA
Authors: Ruan Wenzhi , He Jiansen , Zhang Lei , Vocks Christian , Marsch Eckart , Tu Chuanyi , Peter Hardi , Wang Linghua
Published: June 2016

Quasi-periodic disturbances of emission-line parameters are frequently observed in the corona. These disturbances propagate upward along the magnetic field with speeds of ∼100 km s−1. This phenomenon has been interpreted as evidence of the propagation of slow magnetosonic waves or has been argued to be a signature of intermittent outflows superposed on the background plasmas. Here we aim to present a new “wave + flow” model to interpret these observations. In our scenario, the oscillatory motion is a slow-mode wave, and the flow is associated with a beam created by the wave–particle interaction owing to Landau resonance. With the help of a kinetic model, we simulate the propagation of slow-mode waves and the generation of beam flows. We find that weak periodic beam flows can be generated by to Landau resonance in the solar corona, and the phase with the strongest blueward asymmetry is ahead of that with the strongest blueshift by about 1/4 period. We also find that the slow wave damps to the level of 1/e after the transit time of two wave periods, owing to Landau damping and Coulomb collisions in our simulation. This damping timescale is similar to that resulting from thermal conduction in the MHD regime. The beam flow is weakened/attenuated with increasing wave period and decreasing wave amplitude since Coulomb collisions become more and more dominant over the wave action. We suggest that this “wave + flow” kinetic model provides an alternative explanation for the observed quasi-periodic propagating perturbations in various parameters in the solar corona.