bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disk Sizes in a ΛCDM Universe
Authors: Guo Qi , White Simon 
Published: March 2009

AbstractWe introduce a model which uses semi-analytic techniques to trace formation and evolution of galaxy disks in their cosmological context. For the first time we model the growth of gas and stellar disks separately. In contrast to previous work we follow in detail the angular momentum accumulation history through the gas cooling, merging and star formation processes. Our model successfully reproduces the stellar mass–radius distribution and gas-to-stellar disk size ratio distribution observed locally. We also investigate the dependence of clustering on galaxy size and find qualitative agreement with observation. There is still some discrepancy at small scale for less massive galaxies, indicating that our treatment of satellite galaxies needs to be improved.
What will Gaia tell us about the Galactic disk?
Authors: Bailer-Jones Coryn A. L. 
Published: March 2009

AbstractGaia will provide parallaxes and proper motions with accuracy ranging from 10 to 1000 microarcsecond on up to one billion stars. Most of these will be disk stars: for an unreddened K giant at 6 kpc, it will measure the distance accurate to 2% and the transverse velocity to an accuracy of about 1 km/s. Gaia will observe tracers of Galactic structure, kinematics, star formation and chemical evolution across the whole HR diagram, including Cepheids, RR Lyrae, white dwarfs, F dwarfs and HB stars. Onboard low resolution spectrophotometry will permit – in addition to an effective temperature estimate – dwarf/giant discrimination, metallicity measurement and extinction determination. For the first time, then, Gaia will provide us with a three-dimensional spatial/properties map and at least a two-dimensional velocity map of these tracers. (3D velocities will be obatined for the brighter sources from the onboard RV spectrograph). This will be a goldmine of information from which to learn about the origin and evolution of the Galactic disk. I briefly review the Gaia mission, and then show how the expected astrometric accuracies translate into distance and velocity accuracies and statistics. I then briefly examine the impact Gaia should have on a few scientific areas relevant to the Galactic disk, specifically disk structure and formation, the age–metallicity–velocity relation, the mass–luminosity relation, stellar clusters and spiral structure. Concerning spiral arms, I note how a better determination of their locations and pattern speed from their OB star population, plus a better reconstruction of the Sun's orbit over the past billion years (from integration through the Gaia-measured gravitational potential) will allow us to assess the possible role of spiral arm crossings in ice ages and mass extinctions on the Earth.
The Science of Galaxy Formation
Authors: Gilmore Gerard 
Published: March 2009

AbstractOur knowledge of the Universe remains discovery-led: in the absence of adequate physics-based theory, interpretation of new results requires a scientific methodology. Commonly, scientific progress in astrophysics is motivated by the empirical success of the “Copernican Principle”, that the simplest and most objective analysis of observation leads to progress. A complementary approach tests the prediction of models against observation. In practise, astrophysics has few real theories, and has little control over what we can observe. Compromise is unavoidable. Advances in understanding complex non-linear situations, such as galaxy formation, require that models attempt to isolate key physical properties, rather than trying to reproduce complexity. A specific example is discussed, where substantial progress in fundamental physics could be made with an ambitious approach to modelling: simulating the spectrum of perturbations on small scales.
New mechanisms for international coordination of large observing projects
Authors: Andersen Johannes 
Published: March 2009

AbstractProgress on many fronts in the study of the Milky Way requires major new imaging and/or spectroscopic surveys as well as coordinated ground-based programmes in support of space missions. The present uncoordinated planning and operation of the 2-4m (and some of the larger) telescopes across the world are an impediment to the efficient conduct of such programmes and the overall cost-effectiveness of the investments in astronomy. We briefly report on recent initiatives to improve the situation, notably the part played by the ASTRONET consortium in setting up a comprehensive long-term plan for the development of European astronomy.
Risk of ovarian cancer in women with first‐degree relatives with cancer
Authors: SOEGAARD MARIE , FREDERIKSEN KIRSTEN , JENSEN ALLAN , HØGDALL ESTRID , HØGDALL CLAUS , BLAAKAER JAN , RAMUS SUSAN J. , GAYTHER SIMON A. , KJAER SUSANNE K. 
Published: March 2009

AbstractObjective. To assess the risk of ovarian cancer in women with first‐degree relatives with cancer at one of the four most frequent hereditary sites based on validated cancer diagnoses and to examine the association according to age at diagnosis of ovarian cancer and histology. Design. Case–control study. Setting and population. First‐degree relatives of 554 women with invasive epithelial ovarian cancer and 1,564 controls were included. Methods. Analyses were performed using multiple logistic regression models. Results. Ovarian cancer in a first‐degree relative was significantly associated with increased risk of ovarian cancer (OR, 2.4; 95% CI, 1.4–4.1 (mother or sister)). Ovarian cancer in a first‐degree relative appeared to be a stronger risk factor for early‐onset (≤50 years) ovarian cancer than late‐onset (OR, 5.3; 95% CI, 2.0–14.1 vs. OR, 1.8; 95% CI, 1.0–3.4). The positive association with ovarian cancer family history tended to be with non‐mucinous tumors. Breast cancer in one first‐degree female relative was not significantly associated with risk of ovarian cancer. Conclusion. Ovarian cancer in a first‐degree relative is a very strong predictor of epithelial ovarian cancer, especially early‐onset ovarian cancer. Ovarian cancer in first‐degree relatives seems to be positively associated with especially non‐mucinous tumors.
MIST: Maximum Information Spanning Trees for dimension reduction of biological data sets
Authors: King Bracken M. , Tidor Bruce 
Published: March 2009

Abstract
Motivation: The study of complex biological relationships is aided by large and high-dimensional data sets whose analysis often involves dimension reduction to highlight representative or informative directions of variation. In principle, information theory provides a general framework for quantifying complex statistical relationships for dimension reduction. Unfortunately, direct estimation of high-dimensional information theoretic quantities, such as entropy and mutual information (MI), is often unreliable given the relatively small sample sizes available for biological problems. Here, we develop and evaluate a hierarchy of approximations for high-dimensional information theoretic statistics from associated low-order terms, which can be more reliably estimated from limited samples. Due to a relationship between this metric and the minimum spanning tree over a graph representation of the system, we refer to these approximations as MIST (Maximum Information Spanning Trees).
Results: The MIST approximations are examined in the context of synthetic networks with analytically computable entropies and using experimental gene expression data as a basis for the classification of multiple cancer types. The approximations result in significantly more accurate estimates of entropy and MI, and also correlate better with biological classification error than direct estimation and another low-order approximation, minimum-redundancy–maximum-relevance (mRMR).
Availability: Software to compute the entropy approximations described here is available as Supplementary Material.
Contact: tidor@mit.edu
Supplementary information: Supplementary data are available at Bioinformatics online.
Predictors of Postoperative Acute Renal Failure after Noncardiac Surgery in Patients with Previously Normal Renal Function
Authors: Kheterpal Sachin , Tremper Kevin K. , Englesbe Michael J. , O’Reilly Michael , Shanks Amy M. , Fetterman Douglas M. , Rosenberg Andrew L. , Swartz Richard D. 
Published: March 2009

Background
The authors investigated the incidence and risk factors for postoperative acute renal failure after major noncardiac surgery among patients with previously normal renal function.

Methods
Adult patients undergoing major noncardiac surgery with a preoperative calculated creatinine clearance of 80 ml/min or greater were included in a prospective, observational study at a single tertiary care university hospital. Patients were followed for the development of acute renal failure (defined as a calculated creatinine clearance of 50 ml/min or less) within the first 7 postoperative days. Patient preoperative characteristics and intraoperative anesthetic management were evaluated for associations with acute renal failure. Thirty-day, 60-day, and 1-yr all-cause mortality was also evaluated.

Results
A total of 65,043 cases between 2003 and 2006 were reviewed. Of these, 15,102 patients met the inclusion criteria; 121 patients developed acute renal failure (0.8%), and 14 required renal replacement therapy (0.1%). Seven independent preoperative predictors were identified (P < 0.05): age, emergent surgery, liver disease, body mass index, high-risk surgery, peripheral vascular occlusive disease, and chronic obstructive pulmonary disease necessitating chronic bronchodilator therapy. Several intraoperative management variables were independent predictors of acute renal failure: total vasopressor dose administered, use of a vasopressor infusion, and diuretic administration. Acute renal failure was associated with increased 30-day, 60-day, and 1-yr all-cause mortality.

Conclusions
Several preoperative predictors previously reported to be associated with acute renal failure after cardiac surgery were also found to be associated with acute renal failure after noncardiac surgery. The use of vasopressor and diuretics is also associated with acute renal failure.
Monitoring of Neuromuscular Blockade at the P6 Acupuncture Point Reduces the Incidence of Postoperative Nausea and Vomiting
Authors: Arnberger Michael , Stadelmann Karin , Alischer Petra , Ponert Regina , Melber Andrea , Greif Robert 
Published: March 2009

Background
Electrical stimulation of the P6 acupuncture point reduces the incidence of postoperative nausea and vomiting (PONV). Neuromuscular blockade during general anesthesia can be monitored with electrical peripheral nerve stimulation at the wrist. The authors tested the effect of neuromuscular monitoring over the P6 acupuncture point on the reduction of PONV.

Methods
In this prospective, double-blinded, randomized control trial, the authors investigated, with institutional review board approval and informed consent, 220 women undergoing elective laparoscopic surgery anesthetized with fentanyl, sevoflurane, and rocuronium. During anesthesia, neuromuscular blockade was monitored by a conventional nerve stimulator at a frequency of 1 Hz over the ulnar nerve (n = 110, control group) or over the median nerve (n = 110, P6 group) stimulating at the P6 acupuncture point at the same time. The authors evaluated the incidence of nausea and vomiting during the first 24 h.

Results
No differences in demographic and morphometric data were found between both groups. The 24-h incidence of PONV was 45% in the P6 acupuncture group versus 61% in the control group (P = 0.022). Nausea decreased from 56% in the control group to 40% in the P6 group (P = 0.022), but emesis decreased only from 28% to 23% (P = 0.439). Nausea decreased substantially during the first 6 h of the observation period (P = 0.009). Fewer subjects in the acupuncture group required ondansetron as rescue therapy (27% vs. 39%; P = 0.086).

Conclusion
Intraoperative P6 acupuncture point stimulation with a conventional nerve stimulator during surgery significantly reduced the incidence of PONV over 24 h. The efficacy of P6 stimulation is similar to that of commonly used antiemetic drugs in the prevention of PONV.
Quantification of Epileptiform Electroencephalographic Activity during Sevoflurane Mask Induction
Authors: Särkelä Mika O. K. , Ermes Miikka J. , van Gils Mark J. , Yli-Hankala Arvi M. , Jäntti Ville H. , Vakkuri Anne P. 
Published: March 2009

Background
Sevoflurane may induce epileptiform electroencephalographic activity leading to unstable Bispectral Index numbers, underestimating the hypnotic depth of anesthesia. The authors developed a method for the quantification of epileptiform electroencephalographic activity during sevoflurane anesthesia.

Methods
Electroencephalographic data from 60 patients under sevoflurane mask induction were used in the analysis. Electroencephalographic data were visually classified. A novel electroencephalogram-derived quantity, wavelet subband entropy (WSE), was developed. WSE variables were calculated from different frequency bands. Performance of the WSE in detection and quantification of epileptiform electroencephalographic activity and the ability of the WSE to recognize misleading Bispectral Index readings caused by epileptiform activity were evaluated.

Results
Two WSE variables were found to be sufficient for the quantification of epileptiform activity: WSE from the frequency bands 4-16 and 16-32 Hz. The lower frequency band was used for monophasic pattern monitoring, and the higher frequency band was used for spike activity monitoring. WSE values of the lower and higher bands followed the time evolution of epileptiform activity with prediction probabilities of 0.809 (SE, 0.007) and 0.804 (SE, 0.007), respectively. In deep anesthesia with epileptiform activity, WSE detected electroencephalographic patterns causing Bispectral Index readings greater than 60, with event sensitivity of 97.1%.

Conclusions
The developed method proved useful in detection and quantification of epileptiform electroencephalographic activity during sevoflurane anesthesia. In the future, it may improve the understanding of electroencephalogram-derived information by assisting in recognizing misleading readings of depth-of-anesthesia monitors. The method also may assist in minimizing the occurrence of epileptiform activity and seizures during sevoflurane anesthesia.
Echocardiographic Doppler Estimation of Pulmonary Artery Pressure in Critically Ill Patients with Severe Hypoxemia
Authors: Bouhemad Bélaïd , Ferrari Fabio , Leleu Kris , Arbelot Charlotte , Lu Qin , Rouby Jean-Jacques 
Published: March 2009

Background
In spontaneously breathing cardiac patients, pulmonary artery pressure (PAP) can be accurately estimated from the transthoracic Doppler study of pulmonary artery and tricuspid regurgitation blood flows. In critically ill patients on mechanical ventilation for acute lung injury, the interposition of gas between the probe and the heart renders the transthoracic approach problematic. This study was aimed at determining whether the transesophageal approach could offer an alternative.

Methods
Fifty-one consecutive sedated and ventilated patients with severe hypoxemia (arterial oxygen tension/fraction of inspired oxygen < 300) were prospectively studied. Mean PAP measured from the pulmonary artery catheter was compared with several indices characterizing pulmonary artery blood flow assessed using transesophageal echocardiography: preejection time, acceleration time, ejection duration, preejection time on ejection duration ratio, and acceleration time on ejection duration ratio. In a subgroup of 20 patients, systolic PAP measured from the pulmonary artery catheter immediately before withdrawal was compared with Doppler study of regurgitation tricuspid flow performed immediately after pulmonary artery catheter withdrawal using either the transthoracic or the transesophageal approach.

Results
Weak and clinically irrelevant correlations were found between mean PAP and indices of pulmonary artery flow. A statistically significant and clinically relevant correlation was found between systolic PAP and regurgitation tricuspid flow. In 3 patients (14%), pulmonary artery pressure could not be assessed echocardiographically.

Conclusions
In hypoxemic patients on mechanical ventilation, mean PAP cannot be reliably estimated from indices characterizing pulmonary artery blood flow. Systolic PAP can be estimated from regurgitation tricuspid flow using either transthoracic or transesophageal approach.
On-demand Rather than Daily-routine Chest Radiography Prescription May Change Neither the Number Nor the Impact of Chest Computed Tomography and Ultrasound Studies in a Multidisciplinary Intensive Care Unit
Authors: Kröner Anke , Binnekade Jan M. , Graat Marleen E. , Vroom Margreeth B. , Stoker Jaap , Spronk Peter E. , Schultz Marcus J. 
Published: March 2009

Background
Elimination of daily-routine chest radiographs (CXRs) may influence chest computed tomography (CT) and ultrasound practice in critically ill patients.

Methods
This was a retrospective cohort study including all patients admitted to a university-affiliated intensive care unit during two consecutive periods of 5 months, one before and one after elimination of daily-routine CXR. Chest CT and ultrasound studies were identified retrospectively by using the radiology department information system. Indications for and the diagnostic/therapeutic yield of chest CT and ultrasound studies were collected.

Results
Elimination of daily-routine CXR resulted in a decrease of CXRs per patient day from 1.1 +/- 0.3 to 0.6 +/- 0.4 (P < 0.05). Elimination did not affect duration of stay or mortality rates. Neither the number of chest CT studies nor the ratio of chest CT studies per patient day changed with the intervention: Before elimination of daily-routine CXR, 52 chest CT studies were obtained from 747 patients; after elimination, 54 CT studies were obtained from 743 patients. Similarly, chest ultrasound practice was not affected by the change of CXR strategy: Before and after elimination, 21 and 27 chest ultrasound studies were performed, respectively. Also, timing of chest CT and ultrasound studies was not different between the two study periods. During the two periods, 40 of 106 chest CT studies (38%) and 18 of 48 chest ultrasound studies (38%) resulted in a change in therapy. The combined therapeutic yield of chest CT and ultrasound studies did not change with elimination of daily-routine CXR.

Conclusions
Elimination of daily-routine CXRs may not affect chest CT and ultrasound practice in a multidisciplinary intensive care unit.
Type and Severity of Cognitive Decline in Older Adults after Noncardiac Surgery
Authors: Price Catherine C. , Garvan Cynthia W. , Monk Terri G. 
Published: March 2009

Background
The authors investigated type and severity of cognitive decline in older adults immediately and 3 months after noncardiac surgery. Changes in instrumental activities of daily living were examined relative to type of cognitive decline.

Methods
Of the initial 417 older adults enrolled in the study, 337 surgery patients and 60 controls completed baseline, discharge, and/or 3-month postoperative cognitive and instrumental activities of daily living measures. Reliable change methods were used to examine three types of cognitive decline: memory, executive function, and combined executive function/memory. SD cutoffs were used to grade severity of change as mild, moderate or severe.

Results
At discharge, 186 (56%) patients experienced cognitive decline, with an equal distribution in type and severity. At 3 months after surgery, 231 patients (75.1%) experienced no cognitive decline, 42 (13.6%) showed only memory decline, 26 (8.4%) showed only executive function decline, and 9 (2.9%) showed decline in both executive and memory domains. Of those with cognitive decline, 36 (46.8%) had mild, 25 (32.5%) had moderate, and 16 (20.8%) had severe decline. The combined group had more severe impairment. Executive function or combined (memory and executive) deficits involved greater levels of functional (i.e., instrumental activities of daily living) impairment. The combined group was less educated than the unimpaired and memory groups.

Conclusion
Postsurgical cognitive presentation varies with time of testing. At 3 months after surgery, more older adults experienced memory decline, but only those with executive or combined cognitive decline had functional limitations. The findings have relevance for patients and caregivers. Future research should examine how perioperative factors influence neuronal systems.
A Rat Model of Radicular Pain Induced by Chronic Compression of Lumbar Dorsal Root Ganglion with SURGIFLO ™
Authors: Gu Xiaoping , Yang Liling , Wang Shuxing , Sung Backil , Lim Grewo , Mao Ji , Zeng Qing , Yang Chang , Mao Jianren 
Published: March 2009

Background
Radicular pain is a common and debilitating clinical pain condition. To date, the mechanisms of radicular pain remain unclear, partly because of the lack of suitable preclinical models. The authors report a modified rat model of radicular pain that could mimic a subset of clinical radicular pain conditions induced by the soft tissue compression on dorsal root ganglion.

Methods
A rat model of radicular pain was produced by infiltrating the L5 intervertebral foramen with 60 microl of a hemostatic matrix (SURGIFLO; Johnson & Johnson, Somerville, NJ) resulting in chronic compression of lumbar dorsal root ganglion. Thermal hyperalgesia and mechanical allodynia were measured with or without epidural treatment with triamcinolone. Western blot was used to assess the expression of the NR1 subunit of the N-methyl-D-aspartate receptor and inhibitory factor kappabeta-alpha, an inflammatory marker, within the affected L5 dorsal root ganglion and spinal cord dorsal horn.

Results
Chronic compression of lumbar dorsal root ganglion resulted in: (1) persistent mechanical allodynia and thermal hyperalgesia up to 4 or 5 postoperative weeks and (2) up-regulation of the N-methyl-D-aspartate receptor and inhibitory factor kappabeta-alpha within the ipsilateral L5 dorsal root ganglion and spinal cord dorsal horn. Epidural administration of triamcinolone (6.25-100 microg) on postoperative day 3 dose-dependently attenuated both thermal hyperalgesia and mechanical allodynia in rats with chronic compression of lumbar dorsal root ganglion.

Conclusion
The data suggest that this modified rat model of chronic compression of lumbar dorsal root ganglion may be a useful tool to explore the mechanisms as well as new therapeutic options of radicular pain.