2,772 research outputs found
And yet it moves: The dangers of artificially fixing the Milky Way center of mass in the presence of a massive Large Magellanic Cloud
Motivated by recent studies suggesting that the Large Magellanic Cloud (LMC)
could be significantly more massive than previously thought, we explore whether
the approximation of an inertial Galactocentric reference frame is still valid
in the presence of such a massive LMC. We find that previous estimates of the
LMC's orbital period and apocentric distance derived assuming a fixed Milky Way
are significantly shortened for models where the Milky Way is allowed to move
freely in response to the gravitational pull of the LMC. Holding other
parameters fixed, the fraction of models favoring first infall is reduced. Due
to this interaction, the Milky Way center of mass within the inner 50 kpc can
be significantly displaced in phase-space in a very short period of time that
ranges from 0.3 to 0.5 Gyr by as much as 30 kpc and 75 km/s. Furthermore, we
show that the gravitational pull of the LMC and response of the Milky Way are
likely to significantly affect the orbit and phase space distribution of tidal
debris from the Sagittarius dwarf galaxy (Sgr). Such effects are larger than
previous estimates based on the torque of the LMC alone. As a result, Sgr
deposits debris in regions of the sky that are not aligned with the present-day
Sgr orbital plane. In addition, we find that properly accounting for the
movement of the Milky Way around its common center of mass with the LMC
significantly modifies the angular distance between apocenters and tilts its
orbital pole, alleviating tensions between previous models and observations.
While these models are preliminary in nature, they highlight the central
importance of accounting for the mutual gravitational interaction between the
MW and LMC when modeling the kinematics of objects in the Milky Way and Local
Group.Comment: Accepted for publication in ApJ; 16 pages, 11 figure
Resultados a medio y largo plazo de la utilización de videotoracoscopia en la cirugía de resección de las metástasis pulmonares
The surgical resection of pulmonary metastases is a
method of treatment accepted as habitual in thoracic
surgery. However, it continues to be a source of
controversy if this resection must be realised by
thoracotomy or by modern video-assisted techniques.
With the aim of finding a response to this controversy in
our work milieu, a review was made of the surgical
interventions carried out in order to resect pulmonary
metastases. Between January 1997 and December 2001,
56 patients were found whose pulmonary metastases
had been resected by videothorascopy out of a total of
252 metastasectomies (22.2%). The primary tumours
were classified in 4 groups: sarcoma (n=11); colorectal
(n=25); renal (n=5); and others (n=15). Videothoroscopy
was carried out on the right hemithorax (n=28), left
hemithorax (n=22) or on both at once (n=6). Operational
mortality was nil and the only morbidity attributable to
the technique was a defect of re-expansion following the
removal of the thoracic drainage in one patient. Using
the Kaplan-Meier method, the probability of survival in
this series of patients was 60.4% after 5 years, with an
average survival time of 48 months. All of this data
supports the use of videothorascopy in our milieu on
patients with pulmonary metastases. However, in the
light of the results, it is important in using this technique
to place special emphasis on obtaining good margins of
resection, due to the real risk of local recurrence on
these margins in the medium term
Environmental Clustering of New Zealand Dairy Herds
Previous studies have found that milk yield (a proxy for feeding level) and temperature-humidity index (THI) are important factors in explaining genotype x environment (G x E) interactions, indicating differences between the abilities of genotypes to forage or consume concentrates effectively or to cope with thermal stress (Ravagnolo and Misztal, 2000; Zwald et al., 2003). The objective of this study was to quantify and cluster (CL) herd environments within New Zealand (NZ) based on production levels, a summer heat load index (HLI) and geographical location
Analysis of multiply spliced transcripts in lymphoid tissue reservoirs of rhesus macaques infected with RT-SHIV during HAART.
Highly active antiretroviral therapy (HAART) can reduce levels of human immunodeficiency virus type 1 (HIV-1) to undetectable levels in infected individuals, but the virus is not eradicated. The mechanisms of viral persistence during HAART are poorly defined, but some reservoirs have been identified, such as latently infected resting memory CD4⁺ T cells. During latency, in addition to blocks at the initiation and elongation steps of viral transcription, there is a block in the export of viral RNA (vRNA), leading to the accumulation of multiply-spliced transcripts in the nucleus. Two of the genes encoded by the multiply-spliced transcripts are Tat and Rev, which are essential early in the viral replication cycle and might indicate the state of infection in a given population of cells. Here, the levels of multiply-spliced transcripts were compared to the levels of gag-containing RNA in tissue samples from RT-SHIV-infected rhesus macaques treated with HAART. Splice site sequence variation was identified during development of a TaqMan PCR assay. Multiply-spliced transcripts were detected in gastrointestinal and lymphatic tissues, but not the thymus. Levels of multiply-spliced transcripts were lower than levels of gag RNA, and both correlated with plasma virus loads. The ratio of multiply-spliced to gag RNA was greatest in the gastrointestinal samples from macaques with plasma virus loads <50 vRNA copies per mL at necropsy. Levels of gag RNA and multiply-spliced mRNA in tissues from RT-SHIV-infected macaques correlate with plasma virus load
Patient Perceptions of Trauma-Focused Telemental Health Services Using the Telehealth Satisfaction Questionnaire (TSQ)
Telehealth services can address many barriers to traditional office-based mental health services. Few studies have assessed youth and caregiver perceptions of and satisfaction with trauma-focused interventions delivered via telemental health. The current study presents data collected using the Telehealth Satisfaction Questionnaire (TSQ), which was developed to measure child and caregiver satisfaction with services, comfort with the telehealth equipment, and barriers to traditional office-based services. Thirteen clinicians delivered home- and school-based Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) via videoconferencing on tablets and computers to 60 child patients (71.7% Latinx, 18.3% Black, and 10.0% non-Hispanic White). Patients and caregivers completed the TSQ at treatment discharge via telephone, videoconferencing, or in-person interviews. There was a high level of satisfaction among patients and caregivers receiving TF-CBT via telemental health. Furthermore, most youth and caregivers felt comfortable using the telehealth equipment from the outset of therapy, and all participants who were not initially comfortable using the equipment reported feeling more comfortable over time. The most common barriers to traditional office-based services were caregiver work schedule (57.7%), distance to mental health clinic (55.8%), and lack of transportation (44.2%). Patients and caregivers expressed a preference for telemental health services if given the option between receiving therapy via videoconferencing versus going to an office-based clinic. Findings indicated telemental health treatment addressed barriers that would have otherwise prevented families from accessing office-based services. The Telehealth Satisfaction Questionnaire can be used to help clinics and providers assess patient and caregiver satisfaction with telehealth services in various settings
Interpreter perspectives on working with trauma patients: Challenges and recommendations to improve access to care.
Given the growing number of immigrant and limited-English-proficiency individuals in the U.S., accessing language-congruent services can be a significant barrier for many seeking mental health treatment. The use of spoken-language interpreters can help address this barrier; however, the interpretation in the context of trauma therapy can be particularly challenging for interpreters without mental health training. This quality improvement study explores issues identified by interpreters assisting in the provision of trauma-focused treatment for primarily immigrant populations. Ten certified medical interpreters (nine Spanish-language interpreters and one American Sign Language interpreter) participated in a focus group at a specialty trauma clinic in the southeastern U.S. Core findings concerned the challenges of interpreting (i.e., use of mental health terminology, little time to process emotionally charged sessions, the impact of vicarious trauma, difficulties related to the speed of interpreting and interpreting for multiple patients at once, logistical difficulties, and the availability of interpreters). Interpreters also identified perceived needs and provided recommendations for overcoming challenges (i.e., holding presession meetings with clinicians, ensuring breaks between trauma patients, creating a support group for interpreters, ensuring a direct telephonic line between interpreters and the trauma clinic, providing interpreters with session materials before appointments, and training clinicians on the use of interpreters specifically for trauma treatment). Specific recommendations for agencies and clinicians new to the use of interpreters for trauma-focused services can ultimately enhance service provision for trauma patients in need of language-congruent services
Calculation of a cow culling merit index including specific heterosis in a multibreed dairy population
Abstract. The objective of this study was to compare two models for the estimation of producing values (EPV) for lactation yields of milk, fat and protein, and calving interval (CI), which were combined in an index called the Cow Culling Merit Index (CMI), in Irish dairy cattle. Data comprised 188 927 records for production and 157 117 records for CI, collected on North American Holstein Friesian (HO), Friesian (FR), Jersey (JE), and Montbéliarde (MO) pure breeds, and some of their crosses. Cows calved from 2002 to 2006 and were from parities 1 to 5. Coefficients of specific heterosis for HO×FR, HO×JE, and HO×MO were calculated for each cow from parental breed information. The coefficient of general heterosis (GH) for each cow was obtained as the sum of the specific coefficients previously estimated. Model 1 included fixed effects of contemporary group, age at calving within parity, linear regression on gene proportions for FR, JE, and MO, and linear regression on the coefficient of expected GH. Additive genetic, permanent environmental, and error were random effects. Model 2 was based on Model 1 but GH was replaced by linear regressions on coefficients of expected specific heterosis for HO×FR, HO×JE, and HO×MO. Estimated producing values were calculated as the sum of estimated breeding value, permanent environmental and heterosis effects. The inclusion of coefficients of specific heterosis in the model did not produce re-ranking of animals but important differences in EPVs were observed in crossbred cows. These changes are important if EPVs are used to develop a culling merit index
Improving Deep Brain Stimulation Electrode Performance in vivo Through Use of Conductive Hydrogel Coatings
Active implantable neurological devices like deep brain stimulators have been used over the past few decades to treat movement disorders such as those in people with Parkinson’s disease and more recently, in psychiatric conditions like obsessive compulsive disorder. Electrode-tissue interfaces that support safe and effective targeting of specific brain regions are critical to success of these devices. Development of directional electrodes that activate smaller volumes of brain tissue requires electrodes to operate safely with higher charge densities. Coatings such as conductive hydrogels (CHs) provide lower impedances and higher charge injection limits (CILs) than standard platinum electrodes and support safer application of smaller electrode sizes. The aim of this study was to examine the chronic in vivo performance of a new low swelling CH coating that supports higher safe charge densities than traditional platinum electrodes. A range of hydrogel blends were engineered and their swelling and electrical performance compared. Electrochemical performance and stability of high and low swelling formulations were compared during insertion into a model brain in vitro and the formulation with lower swelling characteristics was chosen for the in vivo study. CH-coated or uncoated Pt electrode arrays were implanted into the brains of 14 rats, and their electrochemical performance was tested weekly for 8 weeks. Tissue response and neural survival was assessed histologically following electrode array removal. CH coating resulted in significantly lower voltage transient impedance, higher CIL, lower electrochemical impedance spectroscopy, and higher charge storage capacity compared to uncoated Pt electrodes in vivo, and this advantage was maintained over the 8-week implantation. There was no significant difference in evoked potential thresholds, signal-to-noise ratio, tissue response or neural survival between CH-coated and uncoated Pt groups. The significant electrochemical advantage and stability of CH coating in the brain supports the suitability of this coating technology for future development of smaller, higher fidelity electrode arrays with higher charge density requirement
Quantity and Fate of Water Salvage as a Result of Saltcedar Control on the Pecos River in Texas
This report presents results for the Subtask 3.3 of the Pecos River Basin Assessment
Project sponsored by the U.S. Environmental Protection Agency (EPA) and the Texas State
Soil and Water Conservation Board (TSSWCB). The overall objective of Subtask 3.3 is to
examine the hydrologic impacts of Tamarix spp. (saltcedar) control along a 5 km segment of
the Pecos River near Mentone, Texas. This report is also based on work supported in part by
the Cooperative State Research, Education, and Extension Service, U.S. Department of
Agriculture, under Agreements No. 2005-34461-15661 and No. 2005-45049-03209, Texas
Cooperative Extension (TCE), and Texas Agricultural Experiment Station (TAES).
As part of the deliverables of this project, an existing monitoring network of 8 wells
was examined and enhanced with 9 additional wells equipped with water level loggers. Land
surface profile and piezometric surface profile were developed to characterize interaction of
surface and groundwater for different seasons as well as for verification of monitored water
levels. Flow measurements were conducted during a release of water from Red Bluff
Reservoir in March 2005 to determine losses or gains within the selected reach. Continued
water level monitoring data provide more detailed information about water exchange
between surface water and groundwater under different flow conditions. Correlation
analyses of river stage and groundwater levels in monitoring boreholes provided further
insight.
Results show that the river is hydraulically connected with shallow groundwater for
this 5 km segment, which is comprised of Sites A and B, near Mentone, Texas in Loving
County. Generally, the river is losing water to the aquifer at both sites. A gentle hydraulic
gradient exists on the east bank of the river while a steeper gradient occurs on the west bank
probably due to different hydrological properties of soils. Seepage from the river not only
recharges the shallow aquifer, but also creates groundwater flow parallel to the channel,
which may eventually discharge back to the river downstream. The reversed hydraulic
gradients also demonstrate complexity of the dynamic relationship between the river and the
aquifer. Water loss at the treated Site A decreased dramatically following saltcedar control
in 2001, and remained very low through 2004. This study conservatively estimates water
salvage of 0.5 – 1.0 acre feet per acre from control of saltcedar at this particular site. Salvaged water most likely contributes to aquifer recharge rather than increased streamflow.
Vegetation return in the form of native grasses and saltcedar re-growth at Site A may be the
cause of corresponding increases in water loss in 2005 and 2006. Site A may also be affected
by the untreated adjacent upriver segment (Site B), resulting in over-estimated water loss.
Although the saltcedar water loss and salvage estimates presented here are believed to be
conservative, the extreme differences in yearly site conditions throughout the study made it
difficult to compare pre and post treatment calculations with confidence. It is recommended
that additional flow measurements for longer reaches, enhanced monitoring of surface water
and groundwater interaction, and further studies on hydrological impacts of saltcedar control
be conducted. For future studies using the paired plot method, it is recommended that both
sites be logged for at least 3 years prior to treatment. To reduce the potential for upriver
treatment affect on downriver study areas, it is recommended that hydrological and
ecological conditions immediately upstream of each plot be alike.U.S. Environmental Protection Agency and the
Texas State Soil and Water Conservation Boar
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