bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of cross‐linked PMMA beads on the mechanical behavior of self‐curing acrylic cements
Authors: Vallo C. I. , Abraham G. A. , Cuadrado T. R. , San Román J.
Published: April 2004

Cross‐linked PMMA beads were prepared with the use of two cross‐linking agents with different chain lengths: triethylene glycol dimethacrylate (TEGDMA) and poly(ethylene glycol) dimethacrylate (PEGDMA). Beads containing 10 wt % TEGDMA and 2, 5, and 10 wt % PEGDMA were synthesized by suspension polymerization. Experimental cement formulations were prepared by replacing part of the PMMA powder phase by an equivalent weight of the cross‐linked beads. The mechanical behavior of the modified cements was carried out by testing the cements in flexure and compression. All cements displayed a higher flexural modulus, which was accompanied with a slight decrease in the flexural strength. The two‐parameter Weibull model, which was used to analyze the flexural strength data, gave a good representation of the fracture load distribution. In cements prepared with beads containing 2 and 5 wt % PEGDMA and 10 wt % TEGDMA, no improvement in the flexural strength was observed. Debonding of the particles from the matrix was considered responsible for the decreased flexural strength. On the contrary, cements prepared with different proportions of beads containing 10 wt % PEGDMA resulted in a markedly increased flexural strength compared with the unmodified cement. An improved reinforcing effect of the cross‐linked beads and a significant degree of bonding with the matrix in these cements account for the superior flexural strength compared with the other composite cements tested. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 407–416, 2004
Upper bounds on the general covering number Cλ(v, k, t, m)
Authors: Bertolo Riccardo , Bluskov Iliya , Hämäläinen Heikki
Published: April 2004

A collection $\cal C$ of k‐subsets (called blocks) of a v‐set X (v) = {1, 2,…, v} (with elements called points) is called a t‐(v, k, m, λ) covering if for every m‐subset M of X (v) there is a subcollection $\cal K$ of $\cal C$ with $|\cal K|\geq \lambda$ such that every block K ∈ $\cal K$ has at least t points in common with M. It is required that v ≥ k ≥ t and v ≥ m ≥ t. The minimum number of blocks in a t‐(v, k, m, λ) covering is denoted by Cλ(v, k, t, m). We present some constructions producing the best known upper bounds on Cλ(v, k, t, m) for k = 6, a parameter of interest to lottery players. © 2004 Wiley Periodicals, Inc.
Biophysical and pharmacological characterization of spermatogenic T‐type calcium current in mice lacking the CaV3.1 (α1G) calcium channel: CaV3.2 (α1H) is the main functional calcium channel in wild‐type spermatogenic cells
Authors: Stamboulian Séverine , Kim Daesoo , Shin Hee‐Sup , Ronjat Michel , De Waard Michel , Arnoult Christophe
Published: April 2004

Mammalian acrosome reaction (AR) requires successive activation of three different types of calcium channels (T‐type channels, Inositol‐3‐phosphate (InsP3) receptors, and TRPC2 channels). All the calcium signaling is under the control of the activation of the first‐one, a T‐type calcium channel. The molecular characterization of the T‐type calcium channel is still a matter of debate, previous reports showing the presence of transcripts for CaV3.1 and CaV3.2 subunits. Using mice deficient for CaV3.1 subunit, we show that the T‐type current density in spermatogenic cells is not reduced in deficient mice versus control mice. We characterized the biophysical and pharmacological properties of T‐type current in spermatogenic cells from CaV3.1 deficient mice. Biophysical and pharmacological properties of spermatogenic T‐type current from wild‐type and CaV3.1 deficient mice demonstrate that CaV3.3 does not contribute to T‐type current. Moreover, nickel and amiloride inhibit T‐type currents in deficient and wild‐type mice with similar potencies. These results demonstrate that T‐type currents in spermatogenic cells is due to CaV3.2 subunit and that CaV3.1 contributes to a very negligible extent to the T‐type currents. Thus, the deficient CaV3.1 mouse model allows the characterization of native CaV3.2 currents in spermatogenic cells. Spermatogenic CaV3.2 currents present specific feature in comparison to the cloned CaV3.2 current so far. More particularly, the time‐dependence of recovery from short‐term inactivation of native spermatogenic CaV3.2 is close to 100 millisecond, a value expected for CaV3.1 current. © 2003 Wiley‐Liss, Inc.
Separation of carbon nanotubes by frit inlet asymmetrical flow field‐flow fractionation
Authors: Moon Myeong Hee , Kang Dukjin , Jung Jaehong , Kim Jongmin
Published: April 2004

Flow field‐flow fractionation (flow FFF), a separation technique for particles and macromolecules, has been used to separate carbon nanotubes (CNT). The carbon nanotube ropes that were purified from a raw carbon nanotube mixture by acidic reflux followed by cross‐flow filtration using a hollow fiber module were cut into shorter lengths by sonication under a concentrated acid mixture. The cut carbon nanotubes were separated by using a modified flow FFF channel system, frit inlet asymmetrical flow FFF (FI AFlFFF) channel, which was useful in the continuous flow operation during injection and separation. Carbon nanotubes, before and after the cutting process, were clearly distinguished by their retention profiles. The narrow volume fractions of CNT collected during flow FFF runs were confirmed by field emission scanning electron microscopy and Raman spectroscopy. Experimentally, it was found that retention of carbon nanotubes in flow FFF was dependent on the use of surfactant for CNT dispersion and for the carrier solution in flow FFF. In this work, the use of flow FFF for the size differentiation of carbon nanotubes in the process of preparation or purification was demonstrated.
In‐situ diffraction investigation of superelastic NiTi shape memory alloys under mechanical stress with neutrons and with synchrotron radiation
Authors: Khalil‐Allafi J. , Hasse B. , Klönne M. , Wagner M. , Pirling Th. , Predki W. , Schmahl W.W.
Published: April 2004

In‐situ diffraction investigations of superelastic NiTi shape memory alloys with neutron and synchrotron x‐ray radiation were used to examine the evolution of the phase state of the material as a function of stress and strain, respectively. The results suggest that the transition from austenite to martensite is not complete even at the end of the superelastic plateau, and that significant load transfer to residual austenite takes place.
Knowledge and Method Base for Shape Memory Alloys
Authors: Welp E. G. , Breidert J.
Published: April 2004

It is often impossible for design engineers to decide whether it is possible to use shape memory alloys (SMA) for a particular task. In case of a decision to use SMA for product development, design engineers normally do not know in detail how to proceed in a correct and beneficial way. In order to support design engineers who have no previous knowledge about SMA and to assist in the transfer of results from basic research to industrial practice, an essential knowledge and method base has been developed. Through carefully conducted literature studies and patent analysis material and design information could be collected. All information is implemented into a computer supported knowledge and method base that provides design information with a particular focus on the conceptual and embodiment design phase. The knowledge and method base contains solution principles and data about effects, material and manufacturing as well as design guidelines and calculation methods for dimensioning and optimization. A browser‐based user interface ensures that design engineers have immediate access to the latest version of the knowledge and method base. In order to ensure a user friendly application, an evaluation with several test users has been carried out. Reactions of design engineers from the industrial sector underline the need for support related to knowledge on SMA.
Algorithms for a network design problem with crossing supermodular demands
Authors: Melkonian Vardges , Tardos Éva
Published: April 2004

We present approximation algorithms for a class ofdirectednetwork design problems. The network design problem is to find a minimum cost subgraph such that for each vertex setSthere are at leastf(S) arcs leaving the setS. In the last 10 years general techniques have been developed for designing approximation algorithms forundirectednetwork design problems. Recently, Kamal Jain gave a 2‐approximation algorithm for the case when the functionfis weakly supermodular. There has been very little progress made ondirectednetwork design problems. The main techniques used for the undirected problems do not have simple extensions to the directed case. András Frank has shown that in a special case when the functionfis intersecting supermodular the problem can be solved optimally. In this article, we use this result to get a 2‐approximation algorithm for a more general case whenfis crossing supermodular. We also extend Jain's techniques to directed problems. We prove that if the functionfis crossing supermodular, then any basic solution of the LP relaxation of our problem contains at least one variable with value greater or equal to ¼. This result implies a 4‐approximation algorithm for the class of directed network design problems. © 2004 Wiley Periodicals, Inc.
What is the appropriate role of the trial statistician in preparing and presenting interim findings to an independent Data Monitoring Committee in the U.S. Cancer Cooperative Group setting?
Authors: Bryant John
Published: April 2004

A recent draft FDA Guidance on the establishment and operation of clinical trial Data Monitoring Committees (DMCs) suggests that statisticians who prepare and present interim analyses to the DMC should be external to the trial sponsor. In the context of the National Cancer Institute (NCI) Cooperative Group program, this recommendation appears to imply that Group study statisticians should be blinded to interim data and excluded from the interim monitoring process in all Cooperative Group trials. In this commentary, it is argued that the benefits of such a policy would be minimal in the Cooperative Group setting and are far outweighed by the tangible benefits of including the study statistician in the monitoring process. Copyright 2004 John Wiley & Sons, Ltd.
A major trial needs three statisticians: why, how and who?
Authors: Pocock Stuart J.
Published: April 2004

The statistical and scientific integrity of a major clinical trial is enhanced by having three distinct statistician roles: the Study Statistician, the Data Monitoring Committee (DMC) Statistician and the Independent Statistician. In any specific trial, careful attention should be given for selecting the right people to perform these tasks effectively. It is important that there are good communications amongst all three statisticians (and between each statistician and the other trialists) while preserving all confidentiality as regards interim results. Specifically regarding the Independent Statistician, it seems appropriate that they be truly independent having no other trial involvement than producing interim reports that inform the DMC (and be not employed by a commercial sponsor) but at the same time be fully aware of the trial protocol, objectives, organization and database. Copyright © 2004 John Wiley Sons, Ltd.
Swelling Characteristics of Native and Chemically Modified Wheat Starches as a Function of Heating Temperature and Time
Authors: Choi Sung‐Gil , Kerr William L.
Published: April 2004

The effects of hydroxypropylation (molar substitution, MS 0.05, 0.12, and 0.18) and cross‐linking (0.03%, 0.1%, and 0.2%) on swelling properties of wheat starch granules at several temperatures and heating times were investigated by laser diffraction particle size analysis. Starch samples were dispersed in water at temperatures ranging from 30 to 90°C, for 1 to 360 min. All starch granules exhibited distinct bimodal size distributions: small B‐granules with mean diameter of 2.3 μm and large A‐granules with mean diameter of 20.4 μm. As temperature increased, the B‐granules swelled more than A‐granules. Swelling of A‐granules sharply increased at 60°C. Swelling was more pronounced with increasing molar substitution of hydroxypropyl groups, while increased swelling was not observed in cross‐linked starches. The dependence of swelling capacity on heating time was different at 60 and 80°C as well as amongst modified starches. As heating time was prolonged, mean granule sizes for native, control, and hydroxypropylated starches at 80°C decreased after reaching maximum size due to loss of granule integrity, while those at 60°C showed no significant change.
Overview of faculty learning communities
Authors: Richlin Laurie , Essington Amy
Published: April 2004

This chapter reports the results of a series of surveys that investigated the locations and attributes of FLCs, including type of institution and FLC sizes, budgets, participants, and activities.
Comparing model checking and logical reasoning for real-time systems
Authors: Dierks Henning
Published: April 2004

We apply both model checking and logical reasoning to a real-time protocol for mutual exclusion. To this end we employ PLC-Automata, an abstract notion of programs for real-time systems. A logic-based semantics in terms of Duration Calculus is used to verify the correctness of the protocol by logical reasoning. An alternative but consistent operational semantics in terms of Timed Automata is used to verify the correctness by model checkers. Since model checking of the full model does not terminate in all cases within an acceptable time we examine abstractions and their influence on model-checking performance. We present two abstraction methods that can be applied successfully for the protocol presented.
Cosmogenic nuclide ages for Last Glacial Maximum moraine at Schnells Ridge, Southwest Tasmania
Authors: Kiernan Kevin , Fifield L. Keith , Chappell John
Published: April 2004

Moraines on Schnells Ridge, southwest Tasmania, have been dated using in situ 10Be. An age of 19,400 ± 600 yr is indicated for the well-preserved innermost moraine from consistent measurements on four large quartzite boulders. This corresponds closely with exposure ages reported by T.T. Barrows et al. (2002, Quaternary Science Reviews 21, 159–173) for Last Glacial Maximum glacial features farther north in Tasmania and southeast Australia. In contrast, ages between 39,000 and 141,000 yr were obtained from a series of boulders on a more extensive outer moraine, indicating that this has had a more complex history.
Competition and Cooperation in Environmental Policy: Individual and Interaction Effects
Authors: HOLZINGER KATHARINA , KNILL CHRISTOPH
Published: April 2004

The theory of regulatory competition suggests a race to the bottom of environmental standards. This theory, however, has not found much empirical support. Several attempts to account for this theoretical failure have been made in the literature, which mainly refer to the underlying assumptions of the theory. In this article, we present an alternative explanation. We argue that in reality regulatory competition is overlapped by other mechanisms affecting the adjustment of national policies. Most important are the effects emerging from regulatory cooperation at the level of the European Union (EU). To arrive at more precise theoretical predictions, we therefore not only analyze the individual effects of competition and cooperation on national policies, but also the impact of their interaction.
Stratigraphy and age of the Lower Cretaceous Pedersen Formation, northern Antarctic Peninsula
Authors: Hathway B. , Riding J.B.
Published: April 2004

The Pedersen Formation includes conglomerate-dominated successions exposed on Pedersen Nunatak (142 m thick) and southern Sobral Peninsula (750–1000 m thick). As re-defined here, it also includes mudstone and sandstone in tectonic contact with Nordenskjöld Formation strata on a nunatak north of the Sobral Peninsula conglomerate outcrops. 40Ar/39Ar ages and palynological data indicate an early Aptian age for the lower part of the formation on Sobral Peninsula. The Pedersen Nunatak strata have yielded conflicting age determinations, although an Early Cretaceous age seems likely. The Sobral Peninsula conglomerates are lithologically similar to, and possibly coeval with, basal Gustav Group strata (Lagrelius Point Formation) on James Ross Island. Although further field sampling is required to resolve the age of the Pedersen Nunatak strata, on present evidence the Pedersen Formation appears to form part of the same tectono-stratigraphic unit as the lower part of the Gustav Group, and we therefore propose that it be included in that group.
The stratigraphy of the Pliocene—lower Pleistocene Bardin Bluffs Formation, Amery Oasis, northern Prince Charles Mountains, Antarctica
Authors: Whitehead J.M. , McKelvey B.C.
Published: April 2004

In the Amery Oasis of the northern Prince Charles Mountains, the glaciomarine Bardin Bluffs Formation of the Pagodroma Group was deposited between the Late Pliocene (<3.1 Ma) and Early Pleistocene (>1 Ma). The formation provides evidence of (i) a reduced East Antarctic ice sheet compared to that of the present day and (ii) a subsequent Plio–Pleistocene ice sheet expansion. The formation consists of two members. The older, basal Member 1 is c. 12.5 m thick and consists of relatively ice-distal silty, sandy and sparsely fossiliferous fjordal strata. Member 1 reflects largely ice-free marine sedimentation c. 250 km inland from the current Amery Ice Shelf edge. The member is restricted to the area about the north-eastern end of Pagodroma Gorge where it infills a chemically weathered erosion surface, cut in the form of a valley on the Permo-Triassic Amery Group. Weathering occurred during aerial exposure of the Amery Oasis in a warmer climate than that of today. The younger Member 2 exceeds 40 m in thickness and is made up of coarse ice proximal glaciomarine diamicts. It overlies disconformably Member 1 at Pagodroma Gorge. Elsewhere, Member 2 rests directly upon a smoothed and striated erosion surface, cut on the Amery Group, which was part of a fjord floor. This erosional surface and the facies contrast between the two members, indicates an East Antarctic Ice Sheet expansion and Lambert Glacier grounding-line advance.
How does oxidative stress relate to thermal tolerance in the Antarctic bivalve Yoldia eightsi?
Authors: Abele Doris , Tesch Claudia , Wencke Petra , Pörtner Hans Otto
Published: April 2004

Short and long-term exposure to elevated temperatures were studied in the Antarctic stenothermal protobranch bivalve Yoldia eightsi (Courthouy) from Potter Cove, King George Island (South Shetland Islands, Antarctica). Above a breakpoint temperature of 2°C – the upper habitat temperature for the Potter Cove Y. eightsi stock – both routine (RMR) and standard metabolic rate (SMR) increased steeply. The fraction of metabolism allocated to SMR, as well as the number of intervals of elevated activity per hour increased significantly with temperature. During acute exposure, ATP concentrations in the foot muscle peaked at 2°C and fell at 5°C, whereas superoxide dismutase (SOD) activity decreased upon warming. Slow stepwise warming to a final temperature of 11°C resulted in a significant decrease of SOD activity. Malondialdehyde concentration increased compared with controls at 0°C. In contrast to the effect of short-term exposure, tissue adenylate concentrations displayed a mild increase at higher temperatures during slow warming, indicating an acclimation response. A switch to anaerobic energy production could not be observed up to 11°C, demonstrating a higher level of thermal tolerance than in other Antarctic ectotherms, or a failure of the relevant pathways in Y. eightsi. The imbalance between pro- and antioxidant processes upon warming indicate oxidative stress to be one feature accompanying early heat stress in Y. eightsi.
KARYOTYPE ASYMMETRY IN GALTONIA AND PSEUDOGALTONIA (HYACINTHACEAE)
Authors: FORREST L. L. , JONG K.
Published: April 2004

The karyotype of a recently described species of Galtonia (Hyacinthaceae), G. regalis, is described and its cytotaxonomic relationship to other members of the genus examined. Since conflicting cytological patterns for the genus exist in the literature, the chromosome compositions of the three other species, G. candicans, G. princeps and G. viridiflora, are re-investigated. This study demonstrates that the karyotype of Galtonia is uniformly asymmetrical and distinctively trimodal, with 2n=16. Also included in this investigation is the allied monotypic genus Pseudogaltonia. Its karyotype is also asymmetrical, but differs from Galtonia in its chromosome number of 2n=18, and in certain other features.
THE FLORA OF THE DRAKENSBERG ALPINE CENTRE
Authors: CARBUTT C. , EDWARDS T. J.
Published: April 2004

The Drakensberg Alpine Centre (DAC) comprises the 40,000km2 high-altitude range of hills, mountain peaks and escarpment plateau bordering the eastern interior of southern Africa. Renowned for its species-rich flora and high levels of endemism, the DAC is here shown to support over 2800 specific and infraspecific native taxa, with c.16% of the angiosperm taxa being endemic, the latter equalling the flora of KwaZulu-Natal. Comparisons of the DAC's largest families and genera are made with those of the Cape Floral Region and KwaZulu-Natal, and the largest families are also compared with those of the Afromontane and Pondoland regions. In addition, comparisons are made between the high-altitude floras of southern and south-central Africa on the basis of their Cape element.
Propagation of the “Great Salinity Anomaly” of the 1990s around the northern North Atlantic
Authors: Belkin Igor M.
Published: April 2004

Time series of T and S extending through 2001 are used to describe propagation of the “Great Salinity Anomaly” of the 1990s (GSA'90s). Comparison of the distance‐time relations for the GSA'70s, '80s, and '90s reveals a substantial intensification of the large‐scale circulation in the northern North Atlantic, especially in the Subarctic Gyre between Newfoundland and the Faroes. The advection rate of the GSA'70s, '80s, and '90s between Newfoundland and the Faroe‐Shetland Channel is conservatively estimated to have been 3.5, 10, and 10 cm/s, respectively. The circulation intensification apparently occurred within a decade between the GSA'70s and '80s. During the next decade the advection rate increased from 10 to 13 cm/s between Newfoundland and Iceland Basin. The GSA'90s was advected towards the Faroe‐Shetland Channel by the northern (Iceland Basin's) branch of the North Atlantic Current, whereas the contribution of the southern branch via the Rockall Trough was minimal.
Crustal deformation measurements in Guerrero, Mexico
Authors: Larson Kristine M. , Lowry A. R. , Kostoglodov Vladimir , Hutton Wallis , Sánchez Osvaldo , Hudnut Ken , Suárez Gerardo
Published: April 2004

GPS measurements of crustal deformation in Guerrero, southern Mexico, include surveys collected between 1992 and 2001 as well as continuous GPS measurements at a few sites. These geodetic observations are used to calculate interseismic deformation rates and assess the presence and possible location of transient deformation during the period encompassing 1992.25 to 2001.75. The data are used to examine transient deformation in 1998 previously described from data at a single site byLowry et al.[2001]. Survey measurements and continuous data from a site near Popocatépetl volcano confirm the 1998 transient, and survey data also suggest another transient occurred following the 14 September 1995 (Mw= 7.3) Copala earthquake. All of the available GPS position estimates have been inverted for a combined model of slip during each event plus the steady state slip on the plate interface. Modeling of the steady state deformation rates confirms that the Guerrero seismic gap is partially frictionally locked at depths shallower than about 25 km and accumulating strain that may eventually be released in a great earthquake. The data also suggest that there is frictional coupling to much greater (>40 km) depths, which releases more frequently in aseismic slip events. The locations and sizes of the transient events are only partially constrained by the available data. However, the transient models which best fit the GPS coordinate time series suggest that aseismic slip was centered downdip of the seismogenic portion of the plate‐bounding thrust in both events, and the moment release had equivalent magnitudesMw= 7.1 + 1.3/−1.0 in 1995–1996 and 7.1 + 0.4/−0.1 in 1998.
A resampling procedure for generating conditioned daily weather sequences
Authors: Clark Martyn P. , Gangopadhyay Subhrendu , Brandon David , Werner Kevin , Hay Lauren , Rajagopalan Balaji , Yates David
Published: April 2004

A method is introduced to generate conditioned daily precipitation and temperature time series at multiple stations. The method resamples data from the historical record “nens” times for the period of interest (nens = number of ensemble members) and reorders the ensemble members to reconstruct the observed spatial (intersite) and temporal correlation statistics. The weather generator model is applied to 2307 stations in the contiguous United States and is shown to reproduce the observed spatial correlation between neighboring stations, the observed correlation between variables (e.g., between precipitation and temperature), and the observed temporal correlation between subsequent days in the generated weather sequence. The weather generator model is extended to produce sequences of weather that are conditioned on climate indices (in this case the Niño 3.4 index). Example illustrations of conditioned weather sequences are provided for a station in Arizona (Petrified Forest, 34.8°N, 109.9°W), where El Niño and La Niña conditions have a strong effect on winter precipitation. The conditioned weather sequences generated using the methods described in this paper are appropriate for use as input to hydrologic models to produce multiseason forecasts of streamflow.
Pharyngeal acid Reflux in Patients with Single and Multiple Otolaryngologic Disorders
Authors: Ulualp Seckin O. , Toohill Robert J. , Shaker Reza
Published: April 2004

OBJECTIVE

This study was designed to determine the prevalence and characteristics of pharyngeal acid reflux (PAR) events in single and multiple otolaryngologic disorders.

METHODS

Sixty‐seven patients with otolaryngologic symptoms and objective findings and 34 healthy control subjects were studied with an ambulatory 24‐hour, 3‐site pharyngoesophageal pH monitoring technique. Otolaryngologic diagnosis included isolated Posterior laryngitis (PL) in 28 patients, isolated chronic rhinosinusitis (SIN) in 12, combined PL and SIN (PL+SIN) in 6, PL plus laryngotracheal stenosis (PL+LTS) in 12, and PL plus vocal cord nodules (PL+VCN) in 9.

RESULTS

PAR events were documented in 68% of patients with PL, 34% of patients with SIN, 67% of patients with PL+SIN, 67% of patients with PL+LTS, 78% of patients with PL+VCN, and 21% of controls. The prevalence of PAR events in patients with isolated PL as well as those with PL combined with other disorders was significantly higher than that in patients without PL and that in controls. As a group, patients with PL had a greater number of PAR events and acid exposure time than other patients and controls. Distal and proximal esophageal reflux parameters were not significantly different among groups.

CONCLUSIONS

The prevalence of PAR is significantly higher in patients with isolated PL compared to patients with other isolated otolaryngologic disorders and in controls. The prevalence of PAR in isolated otolaryngologic disorders other than PL is similar to that in healthy controls. The prevalence of PAR is significantly higher in patients with both PL and other otolaryngologic disorders than in controls and in patients with isolated otolaryngologic disorders.
Maxillofacial Injuries Caused by All‐terrain Vehicle Accidents
Authors: Touma B. Joseph , Ramadan Hassan H. , Bringman Jay J. , Rodman Susan
Published: April 2004

With the rise in Popularity of all‐terrain vehicles (ATVs), especially in rural America, injuries associated with their use are becoming more commonplace. A retrospective review was conducted of 153 patients with ATV‐related injuries seen at West Virginia University Hospitals between January 1990 and June 1996. Of these patients, 33 had maxillofacial injuries. Only 2 of 21 (9.5%) patients noted to be wearing helmets had facial injuries, whereas 17 of 19 (89.5%) patients who had facial injuries were not wearing helmets. Most patients with maxillofacial injuries occurring at night had been drinking alcohol. Injury Severity Scores were worse for those patients with maxillofacial injuries, as well as for those patients who had been drinking alcohol. Patients with maxillofacial injuries were more likely to require a stay in the intensive care unit. Furthermore, children with facial injuries had higher Injury Severity Scores and longer hospital stays than the adults. To reduce these accidents and related injuries, the industry, local and federal governments, and ultimately individuals must change their attitudes regarding these Potentially dangerous vehicles.
Secondary Intention Healing of Exposed Scalp and Forehead Bone after Mohs Surgery
Authors: Becker Gary D. , Adams Lawrence A. , Levin Barry C.
Published: April 2004

For Mohs surgical wounds that show exposed bone (ie, bone denuded of periosteum), healing by secondary intention may be preferable to surgical reconstruction. To determine the appropriateness of secondary intention healing, we reviewed surgical outcome in 205 patients with Mohs wounds of the scalp and forehead that had healed by secondary intention. Of these patients, 38 had Mohs wounds showing exposed bone. The mean area of exposed bone was 1074 mm2; the mean area of exposed soft tissue was 1575 mm2. The mean time for wounds with intact periosteum to epithelialize was 7 weeks; the mean time for bare bone to epithelialize was 13 weeks. All wounds healed without infection or tissue breakdown. We conclude that secondary intention healing of scalp and forehead wounds showing exposed bone is a safe and effective method of wound management after Mohs surgery.
Endoscopic Cerebrospinal Fluid Rhinorrhea Repair: Is a Lumbar Drain Necessary?
Authors: Casiano Roy R. , Jassir David
Published: April 2004

OBJECTIVES

To determine the necessity for lumbar drains during endoscopic cerebrospinal fluid (CSF) rhinorrhea repair.

METHODS

Thirty‐three patients underwent endoscopic repair of CSF rhinorrhea without a lumbar drain during a 7‐year period. The size of the dural defect ranged from a microleak (less than 1 mm dural defect) to a 3‐cm dural defect of the anterior skull base.

RESULTS

All of the procedures in patients with smaller defects (<5 mm) were performed on an outpatient basis. Thirty‐two patients (97%) had complete resolution of their CSF leak after 1 procedure without any recurrence (average follow‐up 29 months).

CONCLUSION

A lumbar drain is not routinely necessary for successful closure of CSF rhinorrhea of any size. Smaller dural defects may be safely performed on an outpatient basis without complications. (Otolaryngol Head Neck Surg 1999;121:745‐50.)
Kinetic simulations of electron response to shear Alfvén waves in magnetospheric plasmas
Authors: Watt C. E. J. , Rankin R. , Marchand R.
Published: April 2004

Standing and traveling shear Alfvén waves contribute to electron acceleration and parallel electric field formation on auroral field lines in the Earth’s magnetosphere. In this paper, the self-consistent coupled Vlasov–Maxwell system for shear Alfvén waves is solved in one dimension. The Vlasov equation is gyro-averaged in order to minimize the number of dimensions in the problem, and to avoid numerical problems with the direct evaluation of the parallel electric field, the electron distribution function is described in terms of a spatial coordinate along the field line, the magnetic moment, and the canonical parallel momentum per unit mass. Some preliminary studies of shear Alfvén wave pulses propagating in a uniform magnetic field on model auroral field lines are presented with an emphasis on the kinetic electron response and the parallel electric field. It is shown that when the full parallel electron dynamics are included, wave–particle interactions result in intensification of the parallel electric field and significant heating of the electrons. It is also demonstrated the acceleration of electrons to speeds of the order of twice the wave phase speed, which has been shown by previous calculations. The results are compared with recent observations made by both the NASA Fast Auroral Snapshot and the Freja satellites.
Dust–ion–acoustic soliton in an inhomogeneous collisional plasma
Authors: Li Yang-fang , Ma J. X. , Li Jing-ju
Published: April 2004

In inhomogeneous dusty plasmas, the ion–dust collisions are nonuniform because of the dependence of the collision rates on plasma densities and the grain charge. The propagation of dust–ion–acoustic solitons in such dusty plasmas is studied using the reductive perturbation method. It is shown that either compressive or rarefactive solitons can exist depending on whether the ion-to-electron density ratio is greater or less than a critical value. The interplay between the effects of the plasma inhomogeneity and the spatially varying collision rates can result in the amplitude distribution from decrease to increase when the soliton propagates from high to low density regions. Different from the homogeneous case, the velocity and width of the soliton increase with distance instead of following the changes of the amplitude.
Ion collisions and the Z-pinch precursor column
Authors: Sherlock M. , Chittenden J. P. , Lebedev S. V. , Haines M. G.
Published: April 2004

During the early stages of a wire array Z-pinch implosion, low density plasma streams toward the axis by virtue of the Lorentz force. This streaming precursor plasma may initially be highly collisionless with respect to ion–ion collisions and therefore cannot be modeled using standard fluid theory. The hybrid method in this paper models both collisional and collisionless behavior with ions exchanging energy and momentum with other ions via a Monte Carlo algorithm equivalent to a small-angle kinetic solution and with an electron fluid via a frictional force. It is shown that the axial stagnation of the plasma flow occurs once the density becomes sufficiently high to initiate a nonlinear rise in electron–ion energy exchange, resulting in the thermal equilibration between radiatively cooling electrons and hot, thermalized ions. This then gives rise to a dense, long-lived precursor column on axis, as observed experimentally. The column is held in place by the kinetic pressure of the streaming precursor plasma, which is balanced by the thermal pressure of the plasma in the column at the column’s edge.
Complexity induced anisotropic bimodal intermittent turbulence in space plasmas
Authors: Chang Tom , Tam Sunny W. Y. , Wu Cheng-chin
Published: April 2004

The “physics of complexity” in space plasmas is the central theme of this exposition. It is demonstrated that the sporadic and localized interactions of magnetic coherent structures arising from the plasma resonances can be the source for the coexistence of nonpropagating spatiotemporal fluctuations and propagating modes. Non-Gaussian probability distribution functions of the intermittent fluctuations from direct numerical simulations are obtained and discussed. Power spectra and local intermittency measures using the wavelet analyses are presented to display the spottiness of the small-scale turbulent fluctuations and the nonuniformity of coarse-grained dissipation that can lead to magnetic topological reconfigurations. The technique of the dynamic renormalization group is applied to the study of the scaling properties of such type of multiscale fluctuations. Charged particle interactions with both the propagating and nonpropagating portions of the intermittent turbulence are also described.
Determination of noncovalent interaction energies from electronic densities
Authors: Ma Yuguang , Politzer Peter
Published: April 2004

Starting from the Hellmann–Feynman theorem, an expression is derived for the interaction energy in forming a noncovalently bound complex. It invokes only classical electrostatics, involving the charge distributions of the components as they are in the complex. We propose a method for obtaining these from the total charge distribution. Integration over the electronic densities is carried out by a numerical procedure slightly modified from that of Gavezzotti. We calculate the interaction energies for four molecular dimers at a variety of computational levels. The results are analyzed and compared to the best estimated values available in the literature.
2-Substituted 5,6-Dihydro-1,3-thiazines from Nitriles and Thiocyanates: a Modification of Meyers's Method
Authors: Liepa Andris J. , Saubern Simon
Published: April 2004

The thiazines (4)–(13) were prepared in high yields from corresponding
nitriles or thiocyanates and 4-mercapto-2-methylbutan-2-ol (2) in
methanesulfonic acid. The use of thiocyanates for preparing
2-sulfur-substituted thiazines is reported herein apparently for the first
time. Thiazines (9) and (10) were observed to exhibit imine–enamine
tautomerization by 1H n.m.r. spectroscopy.
Synthesis, X-Ray Crystal Structure and Tubulin- Binding Properties of a Benzofuran Analogue of the Potent Cytotoxic Agent Combretastatin A4
Authors: Banwell Martin G. , Flynn Bernard L. , Hamel Ernest , Willis Anthony C.
Published: April 2004

The benzofuran (4), a ring-fused analogue of the potent antimitotic agent
combretastatin A4 (1), has been prepared by a convergent route involving
5-endo-dig iodocyclization of
o-hydroxytolan (5) as the key step. Compound (4), which
has been characterized crystallographically as well as spectroscopically, is
inactive as a tubulin-binding agent.
Crystallographic Study on Metal(II) Complexes with N-(2-Nitrophenylsulfonyl)glycine
Authors: Iacopino Daniela , Menabue Ledi , Saladini Monica
Published: April 2004

The interaction of MII ions (MII
=Mn II, CoII,
NiII, CuII,
ZnII, CdII,
PbII) with
N-(2-nitrophenylsulfonyl)- glycine
(NO2psglyH2) leads to the
formation at acidic pH of the complex carboxylate-type
M(NO2psgly-
O)2.x
H2O species. At higher pH the deprotonation reaction of
the sulfonamide nitrogen takes place, leading to the formation of the
M(NO2psgly-N,O).x
H2O species where the ligand acts as a chelating agent
toward the metal ion through the carboxylic oxygen and the deprotonated
sulfonamide nitrogen.
In ternary systems the addition of 2,2′-bipyridine (bpy) allows the
deprotonation of the sulfonamide nitrogen also in presence of metal ions such
as ZnII, CoII and
NiII, which were inactive in the binary system, and the
solid compounds isolated are in the M/bpy/L molar ratio 1 : 1 : 1
(MII = CuII ,
ZnII ) or 1 : 2 : 1(MII =
CoII , NiII,
CdII). Here we describe the crystal and molecular
structures of NO2psglyH2 (1),
[Pb(NO2psgly-N,O)]n
(2),
[Cd(bpy)2(NO2psgly-N,O)].H2O
(3) and
[Cu(bpy)(NO2psgly-N,O)(H2O)]
(4).
Membrane protease proteomics: Isotope-coded affinity tag MS identification of undescribed MT1–matrix metalloproteinase substrates
Authors: Tam Eric M. , Morrison Charlotte J. , Wu Yi I. , Stack M. Sharon , Overall Christopher M.
Published: April 2004

By proteolytic modification of low abundant signaling proteins and membrane receptors, proteases exert potent posttranslational control over cell behavior at the postsecretion level. Hence, substrate discovery is indispensable for understanding the biological role of proteases
in vivo
. Indeed, matrix metalloproteinases (MMPs), long associated with extracellular matrix degradation, are increasingly recognized as important processing enzymes of bioactive molecules. MS is now the primary proteomic technique for detecting, identifying, and quantitating proteins in cells or tissues. Here we used isotopecoded affinity tag labeling and multidimensional liquid chromatography inline with tandem MS to identify MDA-MB-231 breast carcinoma cell proteins shed from the cell surface or the pericellular matrix and extracellular proteins that were degraded or processed after transfection with human membrane type 1-MMP (MT1-MMP). Potential substrates were identified as those having altered protein levels compared with the E240A inactive MT1-MMP mutant or vector transfectants. New substrates were biochemically confirmed by matrix-assisted laser desorption ionization–time-of-flight MS and Edman sequencing of cleavage fragments after incubation with recombinant soluble MT1-MMP
in vitro
. We report many previously uncharacterized substrates of MT1-MMP, including the neutrophil chemokine IL-8, secretory leukocyte protease inhibitor, pro-tumor necrosis factor α, death receptor-6, and connective tissue growth factor, indicating that MT1-MMP is an important signaling protease in addition to its traditionally ascribed roles in pericellular matrix remodeling. Moreover, the high-throughput and quantitative nature of isotope-coded affinity tag labeling combined with tandem MS sequencing is a previously undescribed degradomic screen for protease substrate discovery that should be generally adaptable to other classes of protease for exploring proteolytic function in complex and dynamic biological contexts.
Imaging correlates of brain function in monkeys and rats isolates a hippocampal subregion differentially vulnerable to aging
Authors: Small Scott A. , Chawla Monica K. , Buonocore Michael , Rapp Peter R. , Barnes Carol A.
Published: April 2004

The hippocampal formation contains a distinct population of neurons organized into separate anatomical subregions. Each hippocampal subregion expresses a unique molecular profile accounting for their differential vulnerability to mechanisms of memory dysfunction. Nevertheless, it remains unclear which hippocampal subregion is most sensitive to the effects of advancing age. Here we investigate this question by using separate imaging techniques, each assessing different correlates of neuronal function. First, we used MRI to map cerebral blood volume, an established correlate of basal metabolism, in the hippocampal subregions of young and old rhesus monkeys. Second, we usedin situhybridization to map Arc expression in the hippocampal subregions of young and old rats. Arc is an immediate early gene that is activated in a behavior-dependent manner and is correlated with spike activity. Results show that the dentate gyrus is the hippocampal subregion most sensitive to the effects of advancing age, which together with prior studies establishes a cross-species consensus. This pattern isolates the locus of age-related hippocampal dysfunction and differentiates normal aging from Alzheimer's disease.
Identification of an inhibitor-binding site to HIV-1 integrase with affinity acetylation and mass spectrometry
Authors: Shkriabai Nick , Patil Sachindra S. , Hess Sonja , Budihas Scott R. , Craigie Robert , Burke Terrence R. , Le Grice Stuart F. J. , Kvaratskhelia Mamuka
Published: April 2004

We report a methodology that combines affinity acetylation with MS analysis for accurate mapping of an inhibitor-binding site to a target protein. For this purpose, we used a known HIV-1 integrase inhibitor containing aryl di-
O
-acetyl groups (Acetylated-Inhibitor). In addition, we designed a control compound (Acetylated-Control) that also contained an aryl di-
O
-acetyl group but did not inhibit HIV-1 integrase. Examination of the reactivity of these compounds with a model peptide library, which collectively contained all 20 natural amino acids, revealed that aryl di-
O
-acetyl compounds effectively acetylate Cys, Lys, and Tyr residues. Acetylated-Inhibitor and Acetylated-Control exhibited comparable chemical reactivity with respect to these small peptides. However, these two compounds differed markedly in their interactions with HIV-1 integrase. In particular, Acetylated-Inhibitor specifically acetylated K173 at its inhibitory concentration (3 μM) whereas this site remained unrecognized by Acetylated-Control. Our data enabled creation of a detailed model for the integrase:Acetylated-Inhibitor complex, which indicated that the inhibitor selectively binds at an architecturally critical region of the protein. The methodology reported herein has a generic application for systems involving a variety of ligand–protein interactions.
p300 regulates p53-dependent apoptosis after DNA damage in colorectal cancer cells by modulation of PUMA/p21 levels
Authors: Iyer N. Gopalakrishna , Chin Suet-Feung , Ozdag Hilal , Daigo Yataro , Hu De-En , Cariati Massimiliano , Brindle Kevin , Aparicio Samuel , Caldas Carlos
Published: April 2004

Activation of the tumor suppressor p53 by DNA damage induces either cell cycle arrest or apoptosis, but what determines the choice between cytostasis and death is not clear. In this report, we show that the E1A-binding p300 nucleoprotein is a key determinant of p53-dependent cell fate in colorectal cancer cells: absence of p300 increases apoptosis in response to DNA damage. In addition, p300-deficient (p300
-
) cells fail to undergo G
1
/S arrest after UV irradiation. These abnormalities are associated with prolongation of p53 stability, reduced p53-acetylation, blunting of MDM2 activation, failure to transactivate p21, and a disproportionate increase in PUMA levels. When xenografted, p300
-
cells are more sensitive to chemotherapy with doxorubicin. These results show that p300 is a key regulator of the p53 response and suggest that p300 inhibition could be used to modulate chemotherapy.
Axonal growth of embryonic stem cell-derived motoneurons
in vitro
and in motoneuron-injured adult rats
Authors: Harper James M. , Krishnan Chitra , Darman Jessica S. , Deshpande Deepa M. , Peck Schonze , Shats Irina , Backovic Stephanie , Rothstein Jeffrey D. , Kerr Douglas A.
Published: April 2004

We generated spinal motoneurons from embryonic stem (ES) cells to determine the developmental potential of these cells
in vitro
and their capacity to replace motoneurons in the adult mammalian spinal cord. ES cell-derived motoneurons extended long axons, formed neuromuscular junctions, and induced muscle contraction when cocultured with myoblasts. We transplanted motoneuron-committed ES cells into the spinal cords of adult rats with motoneuron injury and found that ≈3,000 ES cell-derived motoneurons (25% of input) survived for >1 month in the spinal cord of each animal. ES cell-derived axonal growth was inhibited by myelin, and this inhibition was overcome by administration of dibutyryl cAMP (dbcAMP) or a Rho kinase inhibitor
in vitro
and
in vivo
. In transplanted rats infused with dbcAMP, ≈80 ES cell-derived motor axons were observed within the ventral roots of each animal, whereas none were observed in transplanted rats not treated with dbcAMP. Because these cells replicate many of the developmental and mature features of true motoneurons, they are an important biological tool to understand formation of motor units
in vitro
and a potential therapeutic tool to reconstitute neural circuits
in vivo
.
Neutrophils alter the inflammatory milieu by signal-dependent translation of constitutive messenger RNAs
Authors: Lindemann Stephan W. , Yost Christian C. , Denis Melvin M. , McIntyre Thomas M. , Weyrich Andrew S. , Zimmerman Guy A.
Published: April 2004

The mechanisms by which neutrophils, key effector cells of the innate immune system, express new gene products in inflammation are largely uncharacterized. We found that they rapidly translate constitutive mRNAs when activated, a previously unrecognized response. One of the proteins synthesized without a requirement for transcription is the soluble IL-6 receptor α, which translocates to endothelial cells and induces a temporal switch to mononuclear leukocyte recruitment. Its synthesis is regulated by a specialized translational control pathway that is inhibited by rapamycin, a bacterial macrolide with therapeutic efficacy in transplantation, inflammatory syndromes, and neoplasia. Signal-dependent translation in activated neutrophils may be a critical mechanism for alteration of the inflammatory milieu and a therapeutic target.