8,207 research outputs found
Ureteropelvic junction obstruction caused by metastatic cholangiocarcinoma
We describe the rare case of a 61-year-old female with right ureteropelvic junction (UPJ) obstruction caused by metastatic cholangiocarcinoma. Her past medical history was notable for cholangiocarcinoma treated with neoadjuvant chemoradiation and two orthotopic liver transplants six years earlier. Urology was consulted when she presented with flank pain and urinary tract infection. Diagnostic workup demonstrated right UPJ obstruction. She was managed acutely with percutaneous nephrostomy. She subsequently underwent robotic pyeloplasty and intrinsic obstruction of the UPJ was discovered. Histological examination revealed adenocarcinoma, consistent with systemic recurrence of the patient\u27s known cholangiocarcinoma
The loss of parental contact: prevalence and consequences experienced past and present
The loss of a parent is a difficult and potentially very upsetting event for a child. Along with the loss of parental contact and the emotional toll, the death, divorce, abandonment, or imprisonment of a parent can also disrupt many on-going facets of a childâs life, including school, social relationships, athletics, and other interests. Despite the potentially devastating nature of parental loss, relatively little is known about the frequency of parental loss or the consequences of this loss. This study examined the prevalence of parental loss and the consequences experienced in both the short and long term. Two separate interview protocols were used in this study. The first, a brief screening interview to identify individuals who lost contact with a parent during the school years (ages 5-17). The second interview was developed as a more detailed follow-up interview for those individuals who reported having lost a parent between the ages of 5 and 17 years. The survey inquired about six domains including demographic information, consequences of the loss, time window necessary to return to normal functioning, common supports provided to the children leading up to the loss, and supports following the loss of a parent. The prevalence rate assessed by the initial survey showed 12.9% of the participants experienced parental loss between 5-18 years of age. The results show that parental loss is associated with emotional, academic, social and family dynamic consequences. Predictors were determined for the consequences of parental loss and are discussed further in the document. The duration of the consequences can last up to several years following the loss of parental contact
A probability-conserving cross-section biasing mechanism for variance reduction in Monte Carlo particle transport calculations
In Monte Carlo particle transport codes, it is often important to adjust
reaction cross sections to reduce the variance of calculations of relatively
rare events, in a technique known as non-analogous Monte Carlo. We present the
theory and sample code for a Geant4 process which allows the cross section of a
G4VDiscreteProcess to be scaled, while adjusting track weights so as to
mitigate the effects of altered primary beam depletion induced by the cross
section change. This makes it possible to increase the cross section of nuclear
reactions by factors exceeding 10^4 (in appropriate cases), without distorting
the results of energy deposition calculations or coincidence rates. The
procedure is also valid for bias factors less than unity, which is useful, for
example, in problems that involve computation of particle penetration deep into
a target, such as occurs in atmospheric showers or in shielding
Towards a portable and future-proof particle-in-cell plasma physics code
We present the first reported OpenCL implementation of EPOCH3D, an extensible particle-in-cell plasma physics code developed at the University of Warwick. We document the challenges and successes of this porting effort, and compare the performance of our implementation executing on a wide variety of hardware from multiple vendors. The focus of our work is on understanding the suitability of existing algorithms for future accelerator-based architectures, and identifying the changes necessary to achieve performance portability for particle-in-cell plasma physics codes.
We achieve good levels of performance with limited changes to the algorithmic behaviour of the code. However, our results suggest that a fundamental change to EPOCH3Dâs current accumulation step (and its dependency on atomic operations) is necessary in order to fully utilise the massive levels of parallelism supported by emerging parallel architectures
Searching for Earth-mass planets around Centauri: precise radial velocities from contaminated spectra
This work is part of an ongoing project which aims to detect terrestrial
planets in our neighbouring star system Centauri using the Doppler
method. Owing to the small angular separation between the two components of the
Cen AB binary system, the observations will to some extent be
contaminated with light coming from the other star. We are accurately
determining the amount of contamination for every observation by measuring the
relative strengths of the H- and NaD lines. Furthermore, we have
developed a modified version of a well established Doppler code that is
modelling the observations using two stellar templates simultaneously. With
this method we can significantly reduce the scatter of the radial velocity
measurements due to spectral cross-contamination and hence increase our chances
of detecting the tiny signature caused by potential Earth-mass planets. After
correcting for the contamination we achieve radial velocity precision of for a given night of observations. We have also
applied this new Doppler code to four southern double-lined spectroscopic
binary systems (HR159, HR913, HR7578, HD181958) and have successfully recovered
radial velocities for both components simultaneously.Comment: accepted for publication in the International Journal of Astrobiology
(published by Cambridge University Press); will appear in a revised form,
subsequent to editorial input by Cambridge University Pres
The Weihai Observatory search for close-in planets orbiting giant stars
Planets are known to orbit giant stars, yet there is a shortage of planets
orbiting within ~0.5 AU (P<100 days). First-ascent giants have not expanded
enough to engulf such planets, but tidal forces can bring planets to the
surface of the star far beyond the stellar radius. So the question remains: are
tidal forces strong enough in these stars to engulf all the missing planets? We
describe a high-cadence observational program to obtain precise radial
velocities of bright giants from Weihai Observatory of Shandong University. We
present data on the planet host Beta Gem (HD 62509), confirming our ability to
derive accurate and precise velocities; our data achieve an rms of 7.3 m/s
about the Keplerian orbit fit. This planet-search programme currently receives
~100 nights per year, allowing us to aggressively pursue short-period planets
to determine whether they are truly absent.Comment: Accepted for publication in PAS
Association-Sponsored Higher Education for Business: Perceptions of First-Year Students
Association-sponsored learning programs comprise a significant but largely unknown sector of higher education. In North America, for example, almost 500 associations are involved in the education! certification process. This paper begins the process of discovering why individuals enroll in such programmes, rejecting the many other vocationally oriented opportunities available to them. Using data from first-year students enrolled with the Canadian Institute of Management, it was found that the majority were drawn to the Institute through personal business contacts. As well, although other alternatives were investigated, the Institute's reputation, level of difficulty, the perceived "practical" nature of the courses and programme length attracted most students. As to perceptions of âutility," the Institute's learning programme was ranked just below a university degree in management and somewhat higher than a degree in a "non- management" discipline.Les programmes d'enseignement parrainĂ©s par des associations dites profession-nelles constituent une partie importante mais mal connue de l'enseignement supĂ©rieur. En AmĂ©rique du Nord, par exemple, prĂšs de 500 associations participent Ă l'octroi de diplĂŽmes et de brevets professionnels. Le prĂ©sent travail cherche Ă dĂ©couvrir les raisons pour lesquelles les individus s'inscrivent Ă ces programmes et rejettent les innombrables autres possibilitĂ©s de formation disponibles. L'Ă©tude des donnĂ©es concernant les Ă©tudiants de premiĂšre annĂ©e inscrits Ă l'Institut canadien de gestion permit de dĂ©couvrir que la majoritĂ© de ces Ă©tudiants avaient Ă©tĂ© attirĂ©s Ă l'Institut par des contacts personnels et professionnels. De plus, aprĂšs que les Ă©tudiants eurent envisagĂ© les autres formations disponibles, c'est la rĂ©putation de l'Institut, le niveau de difficultĂ© de l'enseignement offert, l'aspect «pratique» des cours et la durĂ©e du programme qui contribuĂšrent Ă attirer bon nombre d'entre eux. Quant Ă 1'« utilitĂ© » du programme, les Ă©tudiants l'ont jugĂ©e lĂ©gĂšrement infĂ©rieure Ă celle d'un diplĂŽme universitaire de gestion et lĂ©gĂšrement supĂ©rieure Ă celle d'un autre diplĂŽme obtenu dans une matiĂšre non reliĂ©e Ă la gestion
Encouraging eyewitnesses to falsely corroborate allegations : effects of rapport-building and incriminating evidence
Building rapport involves developing a harmonious relationship with another person and conveying understanding and acceptance towards that person. Law enforcement officers use rapport-building to help gather information from witnesses. But could rapport-building, in some situations, work to contaminate eyewitness testimony? Research shows that compelling incriminating evidence can lead people to corroborate false accusations made against another person. We investigated whether rapport-building â when combined with either Verbal or Verbal+Visual false evidence â might boost these corroboration rates. Subjects took part in a pseudo-gambling task, in which their counterpart was falsely accused of cheating. Using a 2 (Rapport: Rapport vs. No-rapport) Ă 2 (Incriminating Evidence: Verbal vs. Verbal+Visual) between-subjects design, we persuaded subjects to corroborate the accusation. We found that both rapport and verbal+visual incriminating evidence increased the compliance rate. Even when the incriminating evidence was only presented verbally, rapport-building subjects were almost three times as likely to corroborate a false accusation compared to subjects who did not undergo rapport-building. Our results suggest that although there is widespread and strong support for using rapport-building in interviews, doing so also has the potential to aggravate the contaminating power of suggestive interview techniques
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