bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Versatile Extended Pericranial Flap for Closure of Skull Base Defects
Authors: Smith Jesse E. , Ducic Yadranko 
Published: June 2004

OBJECTIVEWe sought to demonstrate the technical aspects of the extended pericranial flap and its versatility in reconstruction of a variety of skull base defects.STUDY DESIGNWe conducted a retrospective chart review of 32 patients who underwent reconstruction of skull‐base defects with an extended pericranial flap by the senior author (Y.D.) from September 1997 to July 2003.METHODSPatients with skull base defects after trauma or extirpative surgery were reconstructed with either a lateral‐ or an anterior‐based vascularized extended pericranial flap. Variables and outcomes measured included: the size and anatomical location of the defect, need for other flaps, preoperative and/or postoperative radiation therapy and/or chemotherapy, bone flap necrosis, hardware exposure, wound dehiscence, postoperative cerebrospinal fluid (CSF) leak, and meningitis.RESULTSThere was no evidence of flap failure, 2 cases of transient (3 to 4 days) CSF leak without resultant meningitis, 3 patients with hardware exposure, and 2 patients with hydroxyapatite infection. The 2 transient cases of CSF leak both resolved without further surgical intervention or the placement of a lumbar drain.CONCLUSION: Both the lateral and anteriorly based extended pericranial flaps are reliable and versatile flaps associated with minimal morbidity and a low rate of complications when used to reconstruct defects of the anterolateral skull base. (Otolaryngol Head Neck Surg 2004;130:704‐11.)
Acoustic Neuroma Surgical Cost and Outcome by Hospital Volume in California
Authors: Slattery William H. , Schwartz Marc S. , Fisher Laurel M. , Oppenheimer Mark 
Published: June 2004

CONTEXTSuccessful outcome of complex surgical techniques depend on the surgical team's level of experience. However, unless benefit is demonstrated in the presence of cost savings, insurance companies are reluctant to approve care from highly experienced hospitals and surgical teams.OBJECTIVETo determine the relationship between the number of acoustic neuroma surgeries performed at California hospitals with surgical outcome and hospital stay cost.DESIGNAcoustic neuroma surgery information was extracted from the California hospital discharge database and was grouped according to the number of surgeries performed at each hospital.SETTING. A database review of California hospitals.PATIENTSPersons (n= 1,213) undergoing acoustic neuroma surgery at a California hospital between 1996 and 1998.MAIN OUTCOME MEASURESOutcome measures included discharge status (routine vs. not routine), medical procedures indicating surgical complications, total cost of hospitalization, and average cost per hospitalization day. Odds ratios were used to compare the hospital volume groups on likelihood of a routine surgical outcome.RESULTSThe frequency of routine surgical outcome increased as hospital acoustic neuroma surgical volume increased, ranging from 68% among patients in the lowest volume group to 97% in the highest hospital volume group. Patients in the highest hospital volume group were 15 times more likely to have a routine surgical outcome than patients in the lowest hospital volume group. Patients in the second highest volume group were 5 times more likely to have a routine surgical outcome than in the lowest volume group. The two highest volume hospital groups had lower total charges and average charges per day than the two lower volume hospital groups.CONCLUSIONSAcoustic neuroma surgeries at higher volume hospitals had higher frequency of routine discharge, lower frequency of apparent complications, and lower average cost of hospitalization. (Otolaryngol Head Neck Surg 2004;130:726‐35.)
Contact Diode Laser Myringotomy and Mitomycin C in Children
Authors: D'Ereditá Riccardo 
Published: June 2004

OBJECTIVETo investigate the use of contact diode laser myringotomy (C‐LAM), combined with topical mitomycin C, as an alternative method for prolonged middle ear ventilation in children with otitis media with effusion.STUDY DESIGN AND SETTINGProspective study at a tertiary care pediatric institution.METHODSFifteen children enrolled in the study. Mitomycin C was applied to the intact tympanic membrane in the right ears, whereas saline on the left side was used for controls. C‐LAM was then performed in all ears. Outcome measures included healing rate and scarring, ear infection, and long‐term audiometric follow‐up.RESULTSThere was no significant difference in median healing rate. In each group, the median was between the third and fourth month. Normal hearing thresholds were obtained in all children at 2‐year follow‐up.CONCLUSION: C‐LAM proved to be an effective method for medium‐term ventilation, but topical mitomycin C before C‐LAM did not prolong patency rate in our patients. No significant complication was encountered at 2‐year follow‐up. (Otolaryngol Head Neck Surg 2004;130:742‐6.)
Association of Autonomic Dysfunction and Mild Obstructive Sleep Apnea
Authors: Woodson B. Tucker , Brusky Laura T. , Saurajen Adrian , Jaradeh Safwan 
Published: June 2004

BACKGROUNDAutonomic dysfunction (AD) has been independently associated with obstructive sleep apnea (OSA). Autonomic abnormalities are generally considered to be secondary to OSA. Autonomic dysfunction may also contribute to OSA. If AD contributes to OSA, we postulated that abnormalities may be present in mild OSA where the confounding causal effects of hypoxemia and sleep disruption are reduced.OBJECTIVEWe evaluated autonomic function tests and sleep studies in a cohort of subjects with no known diagnosis of OSA.METHODSWe prospectively enrolled a cohort without diagnosed OSA who were part of an ongoing study of vasomotor rhinitis (VMR) for testing. A battery of autonomic nervous system tests (sudomotor and cardiovagal), nonattended polysomnography, and three‐site esophageal/pharyngeal pH monitoring were performed.RESULTSTwenty of 22 patients completed the test battery and 12 (60%) met criteria for OSA (Apnea/Hypopnea Index “AHI” >5 events/hour). AHI correlated to mean tilt table blood pressure decrease (R = 0.58, P = 0.007) and the Valsalva‐mediated phase 2 mean blood pressure decrease (R = 0.52, P = 0.017). OSA severity was related to sympathetic but not parasympathetic abnormalities. No differences in blood pressure responses were related to age, oxygen desaturation nadir, gastroesophageal reflux, VMR, or sleepiness.CONCLUSIONAutonomic abnormalities suggestive of decreased adrenergic tone are associated with mild OSA. These abnormalities may potentially be secondary but may also precede development of OSA. (Otolaryngol Head Neck Surg 2004;130: 643‐8.)
Dynamical and Chemical Evolution of IZw18
Authors: Recchi Simone 
Published: June 2004

AbstractWe study the effect of different star formation regimes on the dynamical and chemical evolution of IZw18, the most metal-poor dwarf galaxy locally known. To do that we adopt a two-dimensional hydrocode coupled with detailed chemical yields originating from Type II and Type Ia supernovae and from intermediate-mass stars. Particular emphasis is devoted to the problem of mixing of metals. We conclude that, under particular conditions, cooling of metals occurs with a timescale of the order of 10 Myr, thus confirming the hypothesis of instantaneous mixing adopted in chemical evolution models. We try to draw conclusions about the star formation history and the age of the last burst in IZw18.
On the Kinematics of Tidal Debris from Omega Cen's Progenitor Galaxy
Authors: Chiba Masashi , Mizutani Arihiro 
Published: June 2004

AbstractThe kinematic properties of tidal debris from an orbiting Galactic satellite is presented, on the assumption that its central part once contained the most massive Galactic globular cluster, ω Cen. We simulate dynamical evolution of a satellite galaxy that follows the present-day and likely past orbits of ω Cen, and analyse the kinematic nature of their tidal debris and randomly generated Galactic stars comprising spheroidal halo and flat disk components. It is found that the debris stars show a retrograde rotation at ∼–100 km s–1, which may accord with a recently discovered stellar stream at a radial velocity of ∼300 km s–1 towards the Galactic longitude of ∼270°. These stars also contribute, only in part, to a reported retrograde motion of the outer halo in the north Galactic pole direction, without significantly modifying local halo kinematics near the Sun. The prospects for future debris searches and the implications for the early evolution of the Galaxy are briefly presented.
Photometric Properties of White Dwarf Dominated Halos
Authors: Lee Hyun-chul , Gibson Brad K. , Fenner Yeshe , Brook Chris B. , Kawata Daisuke , Renda Agostino , Holopainen Janne , Flynn Chris 
Published: June 2004

AbstractUsing stellar population synthesis techniques, we explore the photometric signatures of white dwarf progenitor dominated galactic halos, in order to constrain the fraction of halo mass that may be locked up in white dwarf stellar remnants. We first construct a 109 M⊙ stellar halo using the canonical Salpeter initial stellar mass distribution, and then allow for an additional component of low- and intermediate-mass stars, which ultimately give rise to white dwarf remnants. Microlensing observations towards the Large Magellanic Cloud, coupled with several ground-based proper motion surveys, have led to claims that in excess of 20% of the dynamical mass of the halo (1012 M⊙) might be found in white dwarfs. Our results indicate that (1) even if only 1% of the dynamical mass of the dark halo today could be attributed to white dwarfs, their main sequence progenitors at high redshift (z ≈ 3) would have resulted in halos more than 100 times more luminous than those expected from conventional initial mass functions alone, and (2) any putative halo white dwarf progenitor dominated initial mass function component, regardless of its dynamical importance, would be virtually impossible to detect at the present day, due to its extremely faint surface brightness.
A Model for the Formation of the Milky Way
Authors: Samland Markus 
Published: June 2004

AbstractA new chemodynamical model for the formation and evolution of a Milky Way type galaxy is introduced. In this scenario, the galaxy forms inside a slowly growing dark matter halo in a ΛCDM cosmology. In contrast to the simple merger and collapse scenarios, the galactic mass grows continuously over a Hubble time. The whole formation scenario is simulated with a three-dimensional chemodynamical code. Within this model it is possible to follow the evolution of the galactic substructure in detail. The structure of the galactic components — halo, bulge, and disk — and the kinematical and chemical signatures of the stellar populations in the model are in excellent agreement with data from the Milky Way. The present model provides a detailed formation scenario for the Milky Way Galaxy and it yields new information about its kinematical and chemical history. The model predicts that even galaxies like the Milky Way show phases with supernova-driven galactic winds. However, with a mass loss of the order of only a few per cent of the total baryonic mass, these galaxies are in all probability not the main contributors to the enrichment of the intergalactic medium.
Physical Parameters of SDSS Stars, the Nature of the SDSS ‘Ring around the Galaxy’, and the SEGUE Project
Authors: Beers Timothy C. , Prieto Carlos Allende , Wilhelm Ronald , Yanny Brian , Newberg Heidi 
Published: June 2004

AbstractAlthough the Sloan Digital Sky Survey (SDSS) was primarily envisioned as a tool for understanding the nature of the ‘high redshift’ universe, significant discoveries have already been made at lower redshift, z ∼ 0, through studies of stars in the Milky Way galaxy. We have begun to explore the nature of the Milky Way by detailed investigation of the publicly accessible SDSS archive, using spectroscopically targeted stars of special interest (e.g. field horizontal-branch stars, carbon-enhanced stars, and F- and G-type turnoff stars), as well as the stars originally selected as photometric and reddening standards. The first step is to use the SDSS data (which includes independently calibrated five-band photometry and spectrophotometry of individual stars) to derive reliable estimates of the stellar physical parameters, such as Teff, log g, and [Fe/H], for stars that have been observed to date. Of particular interest, at present, are the stars that are apparently associated with the Monoceros Stream (also known as the SDSS ‘Ring around the Galaxy’), for which we report derived metallicities. The techniques we have developed for derivation of the physical parameters for these stars are presently being applied to other stars in the SDSS database, including the Early Data Release (EDR), as well as the first official public database, DR-1. Here we report on the progress made to date, and comment on what might be explored in the near future from a dedicated extension of the SDSS survey (SEGUE) that specifically targets stars in the Milky Way.
High-Resolution N-body Simulations of Galactic Cannibalism: The Magellanic Stream
Authors: Connors Tim W. , Kawata Daisuke , Maddison Sarah T. , Gibson Brad K. 
Published: June 2004

AbstractHierarchical clustering represents the favoured paradigm for galaxy formation throughout the Universe; due to its proximity, the Magellanic system offers one of the few opportunities for astrophysicists to decompose the full six-dimensional phase-space history of a satellite in the midst of being cannibalised by its host galaxy. The availability of improved observational data for the Magellanic Stream and parallel advances in computational power has led us to revisit the canonical tidal model describing the disruption of the Small Magellanic Cloud and the consequent formation of the Stream. We suggest improvements to the tidal model in light of these recent advances.
Cosmic Helium Production
Authors: Flynn Chris 
Published: June 2004

AbstractK-dwarfs are very long lived, slowly evolving stars, so that their present day helium Y and metal content (metallicity Z) is essentially the same as when they were born. K-dwarfs thus contain a fossil record of the amount of helium and metals which has been produced in successive stellar generations over the lifetime of the Galaxy. We here estimate the amount of helium compared to the amount of metals produced via stellar fusion (Δ Y/ΔZ). We use K-dwarfs in the Hipparcos catalogue for which accurate metallicities and luminosities are available. By including recently measured K-dwarfs with super-solar metallicities we are able to obtain a very significant improvement on previous studies. The best fitting value is ΔY/ΔZ = 2.4 ± 0.4 at the 68% confidence level. Values as low as 1 or as high as 4 are excluded with more than 99% confidence.
Kinematics of the Galactic Bulge from Radial Velocity and Proper Motion Optical Surveys
Authors: Reylé Céline , Robin Annie C. , Picaud Sébastien 
Published: June 2004

AbstractLarge-scale surveys provide new constraints on the structure and evolution of the Milky Way. The population synthesis approach is a useful tool to interpret such data sets and to test scenarios of evolution of the Galaxy. New constraints on Galactic parameters have been obtained from the Besançon model of population synthesis, in particular in the inner regions, thanks to near-infrared surveys less affected by interstellar extinction than the optical ones. We present here a few preliminary comparisons between observed and simulated distributions of proper motions in the direction of the Galactic bulge. Next we discuss how bulge stars can be observed and separated from other populations with the RAVE and Gaia surveys.
Mass to Light Ratio, Initial Mass Function, and Chemical Evolution in Disk Galaxies
Authors: Portinari L. , Sommer-Larsen J. , Tantalo R. 
Published: June 2004

AbstractCosmological simulations of disk galaxy formation, when compared to the observed Tully–Fisher relation, suggest a low mass to light (M/L) ratio for the stellar component in spirals. We show that a number of 'bottom-light' initial mass functions (IMFs) suggested independently in the literature, do imply M/L ratios as low as required, at least for late type spirals (Sbc–Sc). However the typical M/L ratio, and correspondingly the zero point of the Tully–Fisher relation, is expected to vary considerably with Hubble type.Bottom-light IMFs tend to have a metal production in excess of what is typically estimated for spiral galaxies. Suitable tuning of the IMF slope and mass limits, post-supernova fallback of metals onto black holes or metal outflows must then be invoked, to reproduce the observed chemical properties of disk galaxies.
Constraints on the Astrophysical Nature of r-Process Nucleosynthesis Sites from Inhomogeneous Chemical Evolution Models
Authors: Argast Dominik , Samland Markus 
Published: June 2004

AbstractWe present a detailed inhomogeneous chemical evolution study that considers for the first-time neutron star mergers as major r-process sources, and compare this scenario with the ones in which lower-mass (in the range 8–10 M⊙) or higher-mass core-collapse supernovae (with masses ≥20 M⊙) act as dominant r-process sites. We conclude that it is not possible at present to distinguish between the lower-mass and higher-mass supernovae scenarios within the framework of inhomogeneous chemical evolution. However, neutron-star mergers seem to be ruled out as the dominant r-process source, since their low rates of occurrence would lead to r-process enrichment that is not consistent with observations.
Patient‐controlled epidural technique improves analgesia for labor but increases cesarean delivery rate compared with the intermittent bolus technique
Authors: Halonen P. , Sarvela J. , Saisto T. , Soikkeli A. , Halmesmäki E. , Korttila K. 
Published: June 2004

Background:  We tested the hypothesis that patient‐controlled epidural analgesia for labor (PCEA) provides better analgesia and satisfaction than the intermittent bolus technique (bolus) without affecting the mode of delivery.Methods:  We randomized 187 parturients to receive labor analgesia using either the PCEA or bolus technique. The PCEA group received a starting bolus of 14 mg of bupivacaine and 60 µg of fentanyl in a 15‐ml volume, followed by a background infusion (bupivacaine 0.08% and fentanyl 2 µg ml−1) 5 ml h−1 with a 5‐ml bolus and 15‐min lock‐out interval. The bolus group received boluses of 20 mg of bupivacaine and 75 µg of fentanyl in a 15‐ml volume.Results:  Parturients in the PCEA group had significantly (P < 0.05–0.01) less pain during the first and second stages of labor. There was no difference in the spontaneous delivery rate between the groups, but the cesarean delivery rate was significantly (P < 0.05) higher (16.3% vs. 6.7%) in the PCEA group than in the bolus group. Bupivacaine consumption was significantly (P < 0.01) higher (11.2 mg h−1 vs. 9.6 mg h−1) and the second stage of labor was significantly (P < 0.01) longer (70 min vs. 54 min) in the PCEA group than in the bolus group. Patient satisfaction was equally good in both groups.Conclusion:  The PCEA technique provided better pain relief. This was associated with higher bupivacaine consumption, prolongation of the second stage of labor, and an increased rate of cesarean section.
Overdose deaths attributed to methadone and heroin in New York City, 1990–1998
Authors: Bryant W. K. , Galea S. , Tracy M. , Markham Piper T. , Tardiff K. J. , Vlahov D. 
Published: June 2004

ABSTRACTAims  Methadone treatment has been shown to be an effective intervention that can lower the risk of heroin‐induced overdose death. Recent reports have suggested increases in methadone‐induced overdose deaths in several locations in the USA and in Europe. This study investigated the role of methadone and opiates in accidental overdose deaths in New York City.Design  We analysed data from the Office of the Chief Medical Examiner to examine all accidental drug overdose deaths in New York City between 1990 and 1998.Findings  Of 7451 total overdose deaths during this period, there were 1024 methadone‐induced overdose deaths, 4627 heroin‐induced overdose deaths and 408 overdose deaths attributed to both methadone and heroin. Fewer than a third as many accidental overdose deaths were attributed to methadone than were attributed to heroin during this period. The proportion of accidental overdose deaths attributed to methadone did not change appreciably (12.6–15.8% of total overdose mortality), while the proportion of overdose deaths attributed to heroin increased significantly (53.5–64.2%) during the period of study.Conclusions  There was no appreciable increase in methadone‐induced overdose mortality in New York City during the 1990s. Both heroin‐induced overdose mortality and prescriptions of methadone increased during the same interval.
Audio‐computerized self‐interviewing versus face‐to‐face interviewing for research data collection at drug abuse treatment programs
Authors: Perlis Theresa E. , Des Jarlais Don C. , Friedman Samuel R. , Arasteh Kamyar , Turner Charles F. 
Published: June 2004

ABSTRACTAims  To assess audio computer‐assisted self‐interviewing (A‐CASI) as a mode of data collection with injecting drug users (IDUs) entering two drug treatment programs in New York City. A‐CASI has been found to increase reporting of sensitive items among a variety of population subgroups.Design  A ﬁeld test of A‐CASI data collection conducted within an ongoing cross‐sectional study of drug use and HIV risk behaviors among IDUs entering drug treatment. Participants were assigned without bias to either a computer‐assisted interviewer‐administered personal interview (CAPI) or to a mixed CAPI/A‐CASI interview. In the latter, ‘sensitive’ portions (dealing with stigmatized behavior) of the questionnaire were self‐administered through A‐CASI, while the remaining portions were interviewer‐administered.Setting  The Detoxification Program and the Methadone Maintenance Treatment Program (MMTP) at Beth Israel Medical Center in New York City.Participants  Seven hundred and eighty‐three IDUs entering drug treatment.Measurements  Odds ratios and adjusted odds ratios (controlling for demographic differences) for comparison of A‐CASI versus CAPI responses on 111 sensitive questions.Findings  Twenty‐three statistically significant differences (each at P < 0.05), all in the direction of more reporting of the behaviors by the A‐CASI group. Forty‐one per cent of A‐CASI participants said they would prefer any subsequent interviews to be fully A‐CASI and 46% said they would prefer the mixed CAPI/A‐CASI mode.Conclusions  A‐CASI was associated with greater reporting of potentially stigmatized drug, sex and HIV risk behaviors on a moderate number of questions. Moreover, a large majority of participants who used A‐CASI would like to be assigned to this method of data collection in future interviews.