bluuebunny/crossref_metadata_2025 huggingface dataset:
Uniform field emission from aligned carbon nanotubes prepared by CO disproportionation
Authors: Lee Jin Seung , Suh Jung Sang
Published: December 2002

We have fabricated aligned carbon nanotubes (CNTs) by disproportionation of CO on a well-ordered Co nanowire array prepared on a porous anodic aluminum oxide (AAO) template using overdeposition and etching techniques, and studied their field emission properties. CNTs fabricated at 600 °C were well graphitized, uniform in diameter and height, and aligned vertically with respect to the plane of the template; they also showed good field emission properties. The electron field emission was turned on at a field as low as 1.1 V/μm and the enhancement factor was 3520 by assuming a CNT work function of 5 eV. Also, very uniform emission was observed by applying 3.1 V/μm. These good field emission properties may be attributed to good graphitization, uniformity in diameter and height, and vertical alignment of the CNTs fabricated on an AAO template by CO disproportionation.
Realization of wide electron slabs by polarization bulk doping in graded III–V nitride semiconductor alloys
Authors: Jena Debdeep , Heikman Sten , Green Daniel , Buttari Dario , Coffie Robert , Xing Huili , Keller Stacia , DenBaars Steve , Speck James S. , Mishra Umesh K. , Smorchkova Ioulia
Published: December 2002

We present the concept and experimental realization of polarization-induced bulk electron doping in III–V nitride semiconductors. By exploiting the large polarization charges in the III–V nitrides, we are able to create wide slabs of high-density mobile electrons without introducing shallow donors. Transport measurements reveal the superior properties of the polarization-doped electron distributions than comparable shallow donor-doped structures, especially at low temperatures due to the removal of ionized impurity scattering. Such polarization-induced three-dimensional electron slabs can be utilized in a variety of device structures owing to their high conductivity and continuously changing energy gap.
Performance of an x-ray microcalorimeter under ac biasing
Authors: Kuur J. van der , de Korte P. A. J. , Hoevers H. F. C. , Kiviranta M. , Seppä H.
Published: December 2002

Frequency domain multiplexing (FDM) is an attractive option for the readout of imaging arrays of microcalorimeters. Implementation of FDM requires ac biasing of the individual microcalorimeters. In this letter we present a small signal model for the behavior of a microcalorimeter under ac bias. Moreover, we have measured the behavior of the same microcalorimeter under ac (at 46 kHz) and dc bias. These experiments show that the performance of the device is very similar in terms of energy resolution, pulse shapes, and current–voltage characteristics. The measured energy resolution at 5.89 keV is 6.9 eV for ac bias and 5.5 eV for dc bias. The effective time constant in both cases is 100 μs.
Cu/SiO
2−x
nanowires with compositional modulation structure grown via thermal evaporation
Authors: Wang Y. G. , Jin A. Z. , Zhang Z.
Published: December 2002

One-dimensional compositional modulation has been achieved in Cu/SiO2−x nanowires prepared at the substrate temperature of 1000 °C by thermal evaporation of a cuprous oxide and silicon mono-oxide mixture. The synthesized nanowires consist of the Cu spheres uniformly piled up along the longitudinal direction of the nanowires to form a modulation structure with an average period of about 140 nm. This periodicity could be adjusted by changing the CuO concentration in the source materials mixture.
Fabrication and thermal stability of arrays of Fe nanodots
Authors: Liu Kai , Nogués J. , Leighton C. , Masuda H. , Nishio K. , Roshchin I. V. , Schuller Ivan K.
Published: December 2002

We have fabricated arrays of 60-nm-size magnetic Fe nanodots over a 1-cm2-size area using nanoporous alumina membranes as shadow masks. The size and size distribution of the nanodots correlate very well with that of the membrane pores. By placing an antiferromagnetic FeF2 layer underneath the Fe nanodots, an exchange anisotropy can be introduced into the Fe/FeF2 system. We have observed an increase in the magnetic hysteresis loop squareness in biased nanodots, suggesting that exchange bias may be used as a tunable source of anisotropy to stabilize the magnetization in such nanodots.
Nanomechanical resonant structures in nanocrystalline diamond
Authors: Sekaric L. , Parpia J. M. , Craighead H. G. , Feygelson T. , Houston B. H. , Butler J. E.
Published: December 2002

We report the fabrication and the operation of nanomechanical resonant structures in nanocrystalline diamond. For this purpose, continuous diamond films as thin as 80 nm were grown using microwave plasma enhanced chemical vapor deposition. The lateral dimensions of the fabricated structures were as small as 50 nm and the measured mechanical resonant frequencies were up to 640 MHz. The mechanical quality factors were in the range of 2500–3000 at room temperature. The elastic properties of these films obtained via the resonant measurements indicate a Young’s modulus close to that of single-crystal diamond.
Dramatic relativistic effects in atomization energy and volatility of the superheavy Hassium tetroxide and OsO4
Authors: Malli Gulzari L.
Published: December 2002

Ab initio all-electron relativistic Dirac–Fock (DF) and nonrelativistic (NR) Hartree–Fock (HF) self-consistent field (SCF) molecular calculations are reported for the tetrahedral superheavy hassium tetroxide (HsO4) and its lighter congener OsO4 at various M–O (M=Hs,Os) bond lengths. Our relativistic DF and NR HF wave functions predict the ground state of the tetrahedral HsO4 and OsO4 to be bound and the predicted relativistic (nonrelativistic) atomization energy (Ae) for HsO4 and OsO4 is 15.35 (6.83) and 10.32 (5.59) eV, respectively. Relativistic effects lead to dramatic increase of ∼225% and 185% in the predicted Ae of HsO4 and OsO4, respectively. Mulliken population analysis of our relativistic DF (NR HF) wave functions for the HsO4 and OsO4 yields a charge on Hs of +1.06 (+1.14) and Os of +0.88 (+1.94), respectively. Our DF SCF wave function, in contrast to our NR HF wave function, predicts HsO4 to be more ionic, i.e., less volatile than OsO4 and our prediction is in agreement with the recent experimental work for the superheavy element hassium (http://enews.lbl.gov/Science-Articles/Archive/108-chemistry.html, dated 4 June 2001).
Promising ceramic laser material: Highly transparent Nd3+:Lu2O3 ceramic
Authors: Lu J. , Takaichi K. , Uematsu T. , Shirakawa A. , Musha M. , Ueda K. , Yagi H. , Yanagitani T. , Kaminskii A. A.
Published: December 2002

A solid-state laser material based on highly transparent cubic Nd3+:Lu2O3 ceramic was developed using nanocrystalline technology and a nonpress vacuum sintering method. Spectroscopic properties of this ceramic laser material were investigated. At room temperature under single-laser diode pumping, efficient continuous wave laser oscillation was demonstrated at two wavelengths of the 4F3/2→4I11/2 channel. The potential application of such a laser material was also discussed.
1.3 μm continuous-wave GaInNAs/GaAs distributed feedback laser diodes
Authors: Gollub D. , Fischer M. , Kamp M. , Forchel A.
Published: December 2002

GaInNAs/GaAs single-quantum-well lasers were grown by solid-source molecular-beam epitaxy using a radio-frequency source for nitrogen activation. Distributed feedback has been realized by a metal grating arranged laterally to the laser ridge. Single-mode emission between 1271 and 1304 nm could be demonstrated. Room-temperature continuous-wave operation has been obtained with a threshold current of 28 mA, an external efficiency of 0.16 W/A per facet, and a side-mode suppression ratio of 44 dB at 90 mA drive current.
Fiber-loop ring-down spectroscopy
Authors: Brown R. Stephen , Kozin Igor , Tong Zhaoguo , Oleschuk Richard D. , Loock Hans-Peter
Published: December 2002

Pulsed, visible and near-infrared laser light is coupled into an optical fiber, which is wound into a loop using a fiber splice connector. The light pulses traveling through the fiber-loop are detected using a photomultiplier detector. It is found that once the light is coupled into the fiber it experiences very little loss and the light pulses do a large number of round trips before their intensity is below the detection threshold. Measurements of the loss-per-pass and of the ring-down time allow for characterization of the different loss mechanisms of the light pulses in the fiber and splice connector. This method resembles “cavity ring-down absorption spectroscopy” and is well suited to characterize low-loss processes in fiber optic transmission independent from power fluctuations of the light source. It is demonstrated that by measuring the ring-down times one can accurately determine the absolute transmission of an optical fiber and of the fiber connector. In addition it is demonstrated that the technique is useful as an absorption spectroscopic technique of very small sample volumes. A solution of an organic dye was placed between the fiber ends instead of the usual index matching fluid, and an absorption spectrum of 7×10−15 mol of the dye 1,1′-diethyl-4,4′-dicarbocyanine iodide in 7×10−12 L of dimethylsulfoxide was recorded.
Entanglement effects in mode coupling theories of polymers
Authors: Miyazaki Kunimasa , Yethiraj Arun
Published: December 2002

Entanglement effects in polymer melts are investigated using mode coupling theory. For a system of long thin rods that perform only translation motion, we find an exact solution to the mode coupling theory, and demonstrate that it predicts that the self-diffusion coefficient becomes isotropic as the aspect ratio becomes infinite, i.e., it does not describe entanglement effects. One has to go beyond the usual Gaussian approximation in mode coupling theory to obtain nontrivial results for the self-diffusion coefficient, and a simple approximation is investigated which gives results consistent with the reptation theory and a dynamical mean field theory.
Losses for microwave transmission in metamaterials for producing left-handed materials: The strip wires
Authors: Ponizovskaya E. V. , Nieto-Vesperinas M. , Garcia N.
Published: December 2002

This letter shows that the effective permittivity ε for those metamaterials so far used to obtain a left-handed medium, consisting of 0.003 cm thick Cu strip wires, is dominated by the imaginary part of ε at 10.6–11.5 GHz frequencies. This is the region of a bandpass filter for microwaves, and therefore there is no propagation since the wave is inhomogeneous inside the medium. We compare with results of Shelby et al. [Appl. Phys. Lett. 78, 489 (2001)], and find that those are in error by ten orders of magnitude of the transmitted power. Also, from finite-difference time-domain calculations using the actual permittivity value of the Cu wires, we demonstrate that when the structure contains thicker wires, the losses are then reduced and the negative part of the permittivity dominates. Since the thickness of the wires is critical for the realization of a good transparent left-handed material, we propose that the strip wires should have thickness of 0.07–0.1 cm and the split ring resonators should be 0.030–0.06 cm thick.
Pulsed atomic-layer epitaxy of ultrahigh-quality AlxGa1−xN structures for deep ultraviolet emissions below 230 nm
Authors: Zhang J. P. , Khan M. Asif , Sun W. H. , Wang H. M. , Chen C. Q. , Fareed Q. , Kuokstis E. , Yang J. W.
Published: December 2002

In this letter, we report the pulsed atomic-layer epitaxy of ultrahigh-quality AlN epilayers and AlN/Al0.85Ga0.15N multiple quantum wells (MQWs) on basal plane sapphire substrates. Symmetric and asymmetric x-ray diffraction (XRD) measurements and room-temperature (RT) photoluminescence (PL) were used to establish the ultrahigh structural and optical quality. Strong band-edge RT PL at 208 and 228 nm was obtained from the AlN epilayers and the AlN/Al0.85Ga0.15N MQWs. These data clearly establish their suitability for sub-250-nm deep UV emitters.
Complex Carbohydrates Are Not Removed During Processing of Glycoproteins by Dendritic Cells
Authors: Vlad Anda M. , Muller Stefan , Cudic Mare , Paulsen Hans , Otvos Laszlo , Hanisch Franz-Georg , Finn Olivera J.
Published: December 2002

In contrast to protein antigens, processing of glycoproteins by dendritic cells (DCs) for presentation to T cells has not been well studied. We developed mouse T cell hybridomas to study processing and presentation of the tumor antigen MUC1 as a model glycoprotein. MUC1 is expressed on the surface as well as secreted by human adenocarcinomas. Circulating soluble MUC1 is available for uptake, processing, and presentation by DCs in vivo and better understanding of how that process functions in the case of glycosylated antigens may shed light on antitumor immune responses that could be initiated against this glycoprotein. We show that DCs endocytose MUC1 glycopeptides, transport them to acidic compartments, process them into smaller peptides, and present them on major histocompatability complex (MHC) class II molecules without removing the carbohydrates. Glycopeptides that are presented on DCs are recognized by T cells. This suggests that a much broader repertoire of T cells could be elicited against MUC1 and other glycoproteins than expected based only on their peptide sequences.
Polymorphism in a Plasmodium falciparum Erythrocyte-binding Ligand Changes Its Receptor Specificity
Authors: Mayer D.C. Ghislaine , Mu Jian-Bing , Feng Xiaorong , Su Xin-zhuan , Miller Louis H.
Published: December 2002

Recognition of human erythrocytes by Plasmodium species depends in part on Region II of the Duffy binding-like family of parasite ligands, which includes BA erythrocyte binding ligand (BAEBL) of P. falciparum. In previous studies of BAEBL from two clones, Dd2/Nm from Vietnam and E12 from Papua New Guinea (PNG), it was found that BAEBL bound different erythrocyte receptors. Because of variation in binding specificity, we studied the sequence and erythrocyte binding specificity of Region II of BAEBL in P. falciparum clones from different parts of the world. We observed five nucleotide substitutions leading to five amino acid changes and five polymorphisms in Region II of BAEBL in parasites from both PNG and other parts of the world. We expressed four of the polymorphisms on COS cells and determined their binding to enzyme-treated erythrocytes and to Gerbich-negative erythrocytes. We also performed erythrocyte-binding assay using the native protein from radiolabeled culture supernatant. Both assays demonstrated that each of the four polymorphisms in the parasite ligand, BAEBL, bound to a different receptor on erythrocytes. These results suggest that P. falciparum has evolved multiple invasion pathways dependent on polymorphisms in the BAEBL ligand.
Telomerase Activation and Rejuvenation of Telomere Length in Stimulated T Cells Derived from Serially Transplanted Hematopoietic Stem Cells
Authors: Allsopp Richard C. , Cheshier Samuel , Weissman Irving L.
Published: December 2002

Telomeres shorten in hematopoietic cells, including hematopoietic stem cells (HSCs), during aging and after transplantation, despite the presence of readily detectable levels of telomerase in these cells. In T cells, antigenic stimulation has been shown to result in a marked increase in the level of telomerase activity. We now show that stimulation of T cells derived from serially transplanted HSC results in a telomerase-dependent elongation of telomere length to a size similar to that observed in T cells isolated directly from young mice. Southern analysis of telomere length in resting and anti-CD3/CD28 stimulated donor-derived splenic T cells revealed an increase in telomere size by ∼7 kb for the population as a whole. Stimulation of donor-derived T cells from recipients of HSCs from telomerase-deficient mice did not result in regeneration of telomere length, demonstrating a dependence on telomerase. Furthermore, clonal anti-CD3/CD28 stimulation of donor-derived T cells followed by fluorescent in situ hybridization (FISH) analysis of telomeric signal intensity showed that telomeres had increased in size by ∼50% for all clonal expansions. Together, these results imply that one role for telomerase in T cells may be to renew or extend replicative potential via the rejuvenation of telomere length.
Vascular Permeability Factor/Vascular Endothelial Growth Factor Induces Lymphangiogenesis as well as Angiogenesis
Authors: Nagy Janice A. , Vasile Eliza , Feng Dian , Sundberg Christian , Brown Lawrence F. , Detmar Michael J. , Lawitts Joel A. , Benjamin Laura , Tan Xiaolian , Manseau Eleanor J. , Dvorak Ann M. , Dvorak Harold F.
Published: December 2002

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A) is a multifunctional cytokine with important roles in pathological angiogenesis. Using an adenoviral vector engineered to express murine VEGF-A164, we previously investigated the steps and mechanisms by which this cytokine induced the formation of new blood vessels in adult immunodeficient mice and demonstrated that the newly formed blood vessels closely resembled those found in VEGF-A–expressing tumors. We now report that, in addition to inducing angiogenesis, VEGF-A164 also induces a strong lymphangiogenic response. This finding was unanticipated because lymphangiogenesis has been thought to be mediated by other members of the VPF/VEGF family, namely, VEGF-C and VEGF-D. The new “giant” lymphatics generated by VEGF-A164 were structurally and functionally abnormal: greatly enlarged with incompetent valves, sluggish flow, and delayed lymph clearance. They closely resembled the large lymphatics found in lymphangiomas/lymphatic malformations, perhaps implicating VEGF-A in the pathogenesis of these lesions. Whereas the angiogenic response was maintained only as long as VEGF-A was expressed, giant lymphatics, once formed, became VEGF-A independent and persisted indefinitely, long after VEGF-A expression ceased. These findings raise the possibility that similar, abnormal lymphatics develop in other pathologies in which VEGF-A is overexpressed, e.g., malignant tumors and chronic inflammation.
Dynamic Response Analysis of Rotor-Bearing Systems With Cracked Shaft
Authors: Mohiuddin M. A. , Khulief Y. A.
Published: December 2002

A general dynamic model for a large-scale rotor-bearing system with a cracked shaft is introduced. A finite shaft element with a crack is developed using a consistent finite element approach. The model accommodates shafts with tapered portions, multiple disks and anisotropic bearings. The formulation is applicable to rotor-bearing systems with different practical design configurations including intermediate bearings, shaft overhang, and stepped shaft assemblies. A reduced order form of equations of motion is obtained by invoking the actual non-planar (complex) modal transformations. The time-response due to different excitations are calculated, and comparisons are presented to establish the validity and efficiency of the reduced order model. It is hoped that the developed computational scheme offers an efficient and essential core module in establishing other specialized crack detection schemes for rotor-bearing systems.
A New Technique Based on Loops to Investigate Displacement Isomorphism in Planetary Gear Trains
Authors: Prasad Raju Pathapati V. V. N. R. , Rao A. C.
Published: December 2002

The most important step in the structural synthesis of planetary gear trains (PGTs) requires the identification of isomorphism (rotational as well as displacement) between the graphs which represent the kinematic structure of planetary gear train. Previously used methods for identifying graph isomorphism yielded incorrect results. Literature review in this area shows there is inconsistency in results from six link, one degree-of-freedom onwards. The purpose of this paper is to present an efficient methodology through the use of Loop concept and Hamming number concept to detect displacement and rotational isomorphism in PGTs in an unambiguous way. New invariants for rotational graphs and displacement graphs called geared chain hamming strings and geared chain loop hamming strings are developed respectively to identify rotational and displacement isomorphism. This paper also presents a procedure to redraw conventional graph representation that not only clarifies the kinematic structure of a PGT but also averts the problem of pseudo isomorphism. Finally a thorough analysis of existing methods is carried out using the proposed technique and the results in the category of six links one degree-of-freedom are established and an Atlas comprises of graph representations in conventional form as well as in new form is presented.
Full Sliding Adhesive-Like Contact of V-Belts
Authors: Gerbert Go¨ran , Sorge Francesco
Published: December 2002

Analysis of power transmission in a belt drive consisting of, e.g., two pulleys might be treated as a boundary value problem. Tight side tension FT, slack side tension FS and the wrap angle α are the three natural boundary conditions. In the literature, theories are developed where seating and unseating as well as the power transmitting part of the contact are considered. The solutions presented so far don’t fulfill the boundary conditions properly, since a certain tension ratio FT/FS is associated with a certain contact angle and not an a priori specified one. It appears that a new type of full sliding solution must be introduced to handle the boundary condition problem. During part of the contact there is almost no tension variation in spite of the full sliding conditions. The designation adhesive-like solution is here introduced for that part. Conditions and character of the adhesive-like solution are outlined in the paper.
The VOF-G/FEV Model For Tracking a Polymer-Air Interface in the Injection Moulding Process
Authors: Ayad R. , Rigolot A.
Published: December 2002

Based on the control volume technique, mixed with the finite element method, an enhanced numerical approach for tracking flow fronts is presented. The classical governing equations for non-Newtonian fluids are solved by using classical 2D mixed elements and 3D P1+‐P0 element [1] for CPU time considerations. The mixed formulation is used to satisfy the continuity equation. To track the flow front, we present a modified VOF technique labeled “VOF-G/FEV” (FEV: Finite Element and Volume). This method is based on the pseudo-concentration method associated with a control volume technique constructed on the finite element mesh. Numerical examples related to the filling of 2D and 3D geometry cavities are presented. They show good performance of the present tracking approach that can be used successfully for estimating the evolution of polymer fronts in a mould cavity.
Solving the Geometric Design Problem of Spatial 3R Robot Manipulators Using Polynomial Homotopy Continuation
Authors: Lee Eric , Mavroidis Constantinos
Published: December 2002

In this paper, the geometric design problem of serial-link robot manipulators with three revolute (R) joints is solved using a polynomial homotopy continuation method. Three spatial positions and orientations are defined and the dimensions of the geometric parameters of the 3-R manipulator are computed so that the manipulator will be able to place its end-effector at these three pre-specified locations. Denavit and Hartenberg parameters and 4×4 homogeneous matrices are used to formulate the problem and obtain eighteen design equations in twenty-four design unknowns. Six of the design parameters are set as free choices and their values are selected arbitrarily. Two different cases for selecting the free choices are considered and their design equations are solved using polynomial homotopy continuation. In both cases for free choice selection, eight distinct manipulators are found that will be able to place their end-effector at the three specified spatial positions and orientations.
Kinematic Creep in a Continuously Variable Transmission: Traction Drive Mechanics for Cobots
Authors: Gillespie R. Brent , Moore Carl A. , Peshkin Michael , Colgate J. Edward
Published: December 2002

Two continuously variable transmissions are examined, one that relates a pair of linear speeds and another that relates a pair of angular speeds. These devices are elemental in the design of cobots, a new class of robot that creates virtual guiding surfaces to aid a human operator in assembly tasks. Both of these transmissions are traction drive mechanisms that rely on the support of either lateral or longitudinal forces across rolling contacts with spin. When a rolling contact between elastic bodies or even between rigid bodies in spin is called upon to transmit a tractive force, kinematic creep develops, expressing a departure from the intended rolling constraint. Creep in turn gives rise to nonideal properties in a cobot’s virtual guiding surfaces. This paper develops simple models of the two transmissions by expressing the relative velocity field in the contact patch between rolling bodies in terms of creep and spin. Coulomb friction laws are applied in a quasi-static analysis to produce complete force-motion models. These models may be used to evaluate a cobot’s ability to support forces against its virtual guiding surfaces.
Mathematical Models and Contact Simulations of Concave Beveloid Gears
Authors: Liu Chia-Chang , Tsay Chung-Biau
Published: December 2002

This study presents two mathematical models of concave beveloid gears ground by Mitome’s grinding method and by the novel grinding method proposed by the authors. Based on the developed mathematical models, the contact simulations are performed and the characteristics of concave beveloid gear pairs are investigated. Simulation results indicate that our novel grinding method ameliorates the drawback of Mitome’s grinding method by eliminating the transmission error of the helical concave beveloid gear pairs. In contrast to conventional beveloid gear pairs, the gears ground by the proposed novel grinding method not only have larger contact ellipses, but also mesh conjugately with non-parallel axes, although assembly errors exist.
Design and Control of a Compliant Parallel Manipulator
Authors: Sugar Thomas G. , Kumar Vijay
Published: December 2002

We describe a novel design for a compliant arm that can be mounted on a mobile robot. Because the arm is compliant, a mobile robot can manipulate or interact with objects that are not precisely positioned in the environment. The main features of the arm are the in-parallel architecture and a novel control scheme that allows us to easily control the Cartesian stiffness or impedance in the plane. Springs are added in series to the limbs of the parallel manipulator. We analyze one limb and the manipulator to determine its performance when either controlling the force applied to an object or controlling its stiffness. Further, we present experimental results that show the performance of the compliant arm.
The Influence of Gear Design Parameters on Gear Tooth Damage Detection Sensitivity
Authors: Liu Lin , Pines Darryll J.
Published: December 2002

This paper develops an analytical model to simulate the gear mesh contact for a spur gear pair with and without tooth damage. Three common gear tooth faults are simulated including pitting, wear and root cracks. The effect of tooth face width on detection sensitivity for pitting and the effect of crack width on detection sensitivity for crack are investigated. Using static performance measures, such as transmission error, results suggest that basic gear design parameters, such as diametral pitch, pressure angle and number of teeth, may have a significant effect on damage detection sensitivity. It appears that a decrease in diametral pitch will enhance damage detection sensitivity for all the three types of damage. An increase in pressure angle or number of teeth will enhance detection sensitivity for pitting damage, but tends to decrease the sensitivity to crack or wear damage.
Lipid-lowering agents and the risk of hip fracture in a Medicaid population
Authors: Ray W A , Daugherty J R , Griffin M R
Published: December 2002

Context:Three recent nested case-control studies conducted in automated databases suggest that users of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have a risk of hip and other osteoporotic fractures half that of non-users of any lipid-lowering drug. However, this comparison may be biased by unmeasured factors associated with treated hyperlipidemias.

Objective:To compare the risk of hip fracture among users of statins and other lipid-lowering agents, which is less susceptible to bias than the comparisons performed in the previous studies.

Design and setting:Retrospective cohort study conducted in the Tennessee Medicaid program between 1 January 1989 through 31 December 1998.

Subjects:New users of all lipid-lowering drugs and randomly selected non-user controls who at baseline were at least 50 years of age and did not have life threatening illness, nursing home residence, or diagnosed dementia or osteoporosis. There were 12 506 persons with new use of statins, 4798 with new use of other lipid lowering drugs, and 17 280 non-user controls.

Main outcome measure:Fracture of the proximal femur (hip), excluding pathological fractures or those resulting from severe trauma.

Results:During 66 690 person years of follow up, there were 186 hip fractures (2.8 per 1000). Relative to non-users, the adjusted incidence rate ratios (95% confidence interval) were 0.62 (0.45 to 0.85) for statin users and 0.44 (0.26 to 0.95) for other lipid-lowering drugs. When compared directly with the other drugs, the adjusted incidence rate ratio for statins was 1.42 (0.83–2.43).

Conclusion:These data provide evidence that the previously observed protective effect of statins may be explained by unmeasured confounding factors.
Population based study of hospitalised fall related injuries in older people
Authors: Peel N M , Kassulke D J , McClure R J
Published: December 2002

Objective:This study aimed to identify the distribution of fall related injury in older people hospitalised for acute treatment of injury, in order to direct priorities for prevention.

Setting:A follow up study was conducted in the Brisbane Metropolitan Region of Australia during 1998.

Methods:Medical records of patients aged 65 years and over hospitalised with a fall related injury were reviewed. Demographic and injury data were analysed and injury rates calculated using census data as the denominator for the population at risk.

Results:From age 65, hospitalised fall related injury rates increased exponentially for both males and females, with age adjusted incidence rates twice as high in women than men. Fractures accounted for 89% of admissions, with over half being to the hip. Males were significantly more likely than females to have fractured their skull, face, or ribs (p<0.01). While females were significantly more likely than males to have fractured their upper or lower limbs (p<0.01), the difference between proportions of males and females fracturing their hip was not significant. Males were more likely than females (p<0.01) to have fall related head injuries (13% of admissions). Compared with hip fractures, head injuries contributed significantly to the burden of injury in terms of severity, need for intensive care, and excess mortality.

Conclusions:The frequency and impact of hip fractures warrants continued emphasis in falls program interventions for both males and females to prevent this injury. However, interventions that go beyond measures to slow and protect against bone loss are also needed to prevent fall related head injuries.
Child passenger safety: potential impact of the Washington State booster seat law on childcare centers
Authors: Chang B A , Ebel B E , Rivara F P
Published: December 2002

Objectives:To examine factors associated with compliance and with perceived readiness for the new Washington State booster seat law, and to identify perceived barriers to compliance among licensed childcare centers.

Design/methods:Surveys were mailed to a random sample of 550 licensed childcare centers in Washington State, approximately nine months before the law was to go into effect.

Results:Only 18% of centers reported being compliant with the law at the time of the survey. Factors associated with current compliance included awareness and knowledge of the law, and being comfortable asking staff and parents to use booster seats. A lack of center-owned booster seats was associated with a lower likelihood of compliance. Only 43% of centers had already started preparing for the law, and only 48% believed they would definitely be ready in time.

Conclusion:This study suggests that Washington State childcare centers need support and assistance to increase their knowledge of booster seats and reduce the financial costs of compliance.
Effectiveness of Ford’s belt reminder system in increasing seat belt use
Authors: Williams A F , Wells J K , Farmer C M
Published: December 2002

Objectives:The study investigated the effectiveness in increasing seat belt use of Ford’s belt reminder system, a supplementary system that provides intermittent flashing lights and chimes for five minutes if drivers are not belted.

Methods:Seat belt use of drivers in relatively new cars with and without the reminder system was unobtrusively observed as vehicles were brought to dealerships for service.

Results:Overall use rates were estimated at 71% for drivers in vehicles without the reminder system and 76% for drivers in vehicles with belt reminders (p<0.01).

Conclusions:Seat belt use is relatively low in the United States. The present study showed that vehicle based reminder systems can be at least modestly effective in increasing belt use, which may encourage further development of such systems.
Fatal occupational electrocutions in the United States
Authors: Taylor A J , McGwin G , Valent F , Rue L W
Published: December 2002

Introduction:The highest proportions of fatal occupational electrocutions have occurred among those employed in the electrical trades and in the construction and manufacturing industries.

Methods:Data from 1992 through 1999 were obtained from the Bureau of Labor Statistics Census of Fatal Occupational Injuries.

Results:Occupational electrocution deaths occurred almost entirely among males, with the highest rates among those aged 20–34 and among whites and American Indians. They were highest during the summer months, in the South, and in establishments employing 10 or fewer workers. The highest rates occurred in the construction, mining, and agriculture, forestry, and fishing industries and among trades associated with these industries.

Conclusions:Electrocution continues to be a significant cause of occupational death. Workers need to be provided with safety training and employers, particularly smaller employers, persuaded of the need for safety training.
Identification and characteristics of victims of violence identified by emergency physicians, triage nurses, and the police: Figure 1
Authors: Howe A , Crilly M
Published: December 2002

Objectives:The objectives of the study were threefold—to evaluate the identification and characteristics of victims of assault who attend an accident and emergency (A&E) department; to compare the total number of assaults recorded in the A&E department with the number recorded by the police; and to assess a system for collecting the location and method of assault.

Setting:The A&E department of Chorley and South Ribble Hospital Trust, Lancashire, England.

Methods:A three month prospective study was performed. Victims of violence recorded on computer by doctors at discharge were compared with those identified at initial nurse triage. A comparison of police data with the A&E data relating to Chorley residents was performed. Additional information on the method and location of assault was also collected.

Results:During the period 305 (2.6%) of the patients attending A&E were identified as having been assaulted. Of the 305 individuals, 236 (77%) were identified by a doctor while 173 (57%) such patients were identified by a triage nurse. A&E identified twice the number of assaults involving Chorley residents as the police. Both men and women were most likely to have been injured on the street (44% and 37% respectively), although a greater proportion of women were injured at home (24%) than men (10%). The majority of injuries were sustained by blows from fists, feet, and heads (73%).

Conclusions:A&E doctors identify significantly more patients as the victims of violence than do nurses at triage. Using A&E data identifies assaulted individuals not identified by the police. Computer systems can be used in A&E to provide a more complete picture of the occurrence of violence in the community.
Implementation of a system of surveillance of childhood injuries involved in a Safe Community program: the example of Boulogne-Billancourt (France)
Authors: Sznajder M , Chevallier B , Yacoubovitch J , Aegerter P , Auvert B
Published: December 2002

Objectives:To provide precise information about child injuries, intended to promote preventive actions, in keeping with the general pattern of a Safe Community program implemented in Boulogne-Billancourt (France) since 1997.

Methods:Information about children under 16 injured in the city of Boulogne-Billancourt and its surroundings, are extracted in a database.

Discussion:The Boulogne-Billancourt database is the first permanent and specific childhood injury surveillance system in France integrated in a “Safe Community”. It may constitute an “alarm system” by allowing rapid implementation of preventive action. The final evaluation of the collected data will be performed at the end of the program (after five years).
Association of seat belt use with death: a comparison of estimates based on data from police and estimates based on data from trained crash investigators
Authors: Cummings P
Published: December 2002

Objective:Estimates of any protective effect of seat belts could be exaggerated if some crash survivors falsely claimed to police that they were belted in order to avoid a fine. The aim of this study was to determine whether estimates of seat belt effectiveness differed when based on belt use as recorded by the police and belt use determined by trained crash investigators.

Design:Matched cohort study.

Setting:United States.

Subjects:Adult driver-passenger pairs in the same vehicle with at least one death (n=1689) sampled from crashes during 1988–2000; data from the National Accident Sampling System Crashworthiness Data System.

Main outcome measure:Risk ratio for death among belted occupants compared with those not belted.

Results:Trained investigators determined post-crash seat belt use by vehicle inspections for 92% of the occupants, confidential interviews with survivors for 5%, and medical or autopsy reports for 3%. Using this information, the adjusted risk ratio for belted persons was 0.36 (95% confidence interval 0.29 to 0.46). The risk ratio was also 0.36 using police reported belt use for the same crashes.

Conclusions:Estimates of seat belt effects based upon police data were not substantially different from estimates which used data obtained by trained crash investigators who were not police officers. These results were from vehicles in which at least one front seat occupant died; these findings may not apply to estimates which use data from crashes without a death.
NONTARGETEFFECTS—THEACHILLES' HEEL OFBIOLOGICALCONTROL? Retrospective Analyses to Reduce Risk Associated with Biocontrol Introductions
Authors: Louda S.M. , Pemberton R.W. , Johnson M.T. , Follett P.A.
Published: December 2002

▪ Abstract  Controversy exists over ecological risks in classical biological control. We reviewed 10 projects with quantitative data on nontarget effects. Ten patterns emerged: (a) Relatives of the pest are most likely to be attacked; (b) host-specificity testing defines physiological host range, but not ecological range; (c) prediction of ecological consequences requires population data; (d) level of impact varied, often in relation to environmental conditions; (e) information on magnitude of nontarget impact is sparse; (f) attack on rare native species can accelerate their decline; (g) nontarget effects can be indirect; (h) agents disperse from agroecosystems; (i) whole assemblages of species can be perturbed; and (j) no evidence on adaptation is available in these cases. The review leads to six recommendations: Avoid using generalists or adventive species; expand host-specificity testing; incorporate more ecological information; consider ecological risk in target selection; prioritize agents; and pursue genetic data on adaptation. We conclude that retrospective analyses suggest clear ways to further increase future safety of biocontrol.
Role of Arthropod Saliva in Blood Feeding: Sialome and Post-Sialome Perspectives
Authors: Ribeiro José M. C. , Francischetti Ivo M. B.
Published: December 2002

This review addresses the problems insects and ticks face to feed on blood and the solutions these invertebrates engender to overcome these obstacles, including a sophisticated salivary cocktail of potent pharmacologic compounds. Recent advances in transcriptome and proteome research allow an unprecedented insight into the complexity of these compounds, indicating that their molecular diversity as well as the diversity of their targets is still larger than previously thought.
Surface Membranes, Golgi Complexes, and Vacuolar Systems
Authors: Locke Michael
Published: December 2002

In the absence of fossils, the cells of vertebrates are often described in lieu of a general animal eukaryote model, neglecting work on insects. However, a common ancestor is nearly a billion years in the past, making some vertebrate generalizations inappropriate for insects. For example, insect cells are adept at the cell remodeling needed for molting and metamorphosis, they have plasma membrane reticular systems and vacuolar ferritin, and their Golgi complexes continue to work during mitosis. This review stresses the ways that insect cells differ from those of vertebrates, summarizing the structure of surfacce membranes and vacuolar systems, especially of the epidermis and fat body, as a prerequisite for the molecular studies needed to understand cell function. The objective is to provide a structural base from which molecular biology can emerge from biochemical description into a useful analysis of function.
GRASSES ANDGALLMIDGES: Plant Defense and Insect Adaptation
Authors: Harris M. O. , Stuart J. J. , Mohan M. , Nair S. , Lamb R. J. , Rohfritsch O.
Published: December 2002

▪ Abstract  The interactions of two economically important gall midge species, the rice gall midge and the Hessian fly, with their host plants, rice and wheat, respectively, are characterized by plant defense via R genes and insect adaptation via avr genes. The interaction of a third gall midge species, the orange wheat blossom midge, with wheat defense R genes has not yet exhibited insect adaptation. Because of the simple genetics underlying important aspects of these gall midge–grass interactions, a unique opportunity exists for integrating plant and insect molecular genetics with coevolutionary ecology. We present an overview of some genetic, physiological, behavioral, and ecological studies that will contribute to this integration and point to areas in need of study.
GENOMICS IN PURE AND APPLIED ENTOMOLOGY
Authors: Heckel David G.
Published: December 2002

▪ Abstract  Genomics is the study of the structure and function of the genome: the set of genetic information encoded in the DNA of the nucleus and organelles of an organism. It is a dynamic field that combines traditional paths of inquiry with new approaches that would have been impossible without recent technological developments. Much of the recent focus has been on obtaining the sequence of entire genomes, determining the order and organization of the genes, and developing libraries that provide immediate physical access to any desired DNA fragment. This has enabled functional studies on a genome-wide level, including analysis of the genetic basis of complex traits, quantification of global patterns of gene expression, and systematic gene disruption projects. The successful contribution of genomics to problems in applied entomology requires the cooperation of the private and public sectors to build upon the knowledge derived from the Drosophila genome and effectively develop models for other insect Orders.
CONTACTCHEMORECEPTION INFEEDING BYPHYTOPHAGOUSINSECTS
Authors: Chapman R. F.
Published: December 2002

▪ Abstract  Gustatory receptors associated with feeding in phytophagous insects are broadly categorized as phagostimulatory or deterrent. No phytophagous insect is known that tastes all its essential nutrients, and the ability to discriminate between nutrients is limited. The insects acquire a nutritional balance largely “adventitiously” because leaves have an appropriate chemical composition. Sugars are the most important phagostimulants. Plant secondary compounds are most often deterrent but stimulate phagostimulatory cells if they serve as host-indicating sign stimuli, or if they are sequestered for defense or used as pheromone precursors. The stimulating effects of chemicals are greatly affected by other chemicals in mixtures like those to which the sensilla are normally exposed. Host plant selection depends on the balance of phagostimulatory and deterrent inputs with, in some oligophagous and monophagous species, a dominating role of a host-related chemical. Evolution of phytophagy has probably involved a change in emphasis in the gustatory system, not fundamentally new developments. The precise role of the gustatory systems remains unclear. In grasshoppers, it probably governs food selection and the amounts eaten, but in caterpillars there is some evidence that central feedbacks are also involved in regulating the amount eaten.
MANAGEMENT OF AGRICULTURAL INSECTS WITH PHYSICAL CONTROL METHODS
Authors: Vincent Charles , Hallman Guy , Panneton Bernard , Fleurat-Lessard Francis
Published: December 2002

▪ Abstract  Ideally, integrated pest management should rely on an array of tactics. In reality, the main technologies in use are synthetic pesticides. Because of well-documented problems with reliance on synthetic pesticides, viable alternatives are sorely needed. Physical controls can be classified as passive (e.g., trenches, fences, organic mulch, particle films, inert dusts, and oils), active (e.g., mechanical, polishing, pneumatic, impact, and thermal), and miscellaneous (e.g., cold storage, heated air, flaming, hot-water immersion). Some physical methods such as oils have been used successfully for preharvest treatments for decades. Another recently developed method for preharvest situations is particle films. As we move from production to the consumer, legal constraints restrict the number of options available. Consequently, several physical control methods are used in postharvest situations. Two noteworthy examples are the entoleter, an impacting machine used to crush all insect stages in flour, and hot-water immersion of mangoes, used to kill tephritid fruit fly immatures in fruit. The future of physical control methods will be influenced by sociolegal issues and by new developments in basic and applied research.