bluuebunny/crossref_metadata_2025 huggingface dataset:
Microcrystalline silicon thin films studied using spectroscopic ellipsometry
Authors: Kang T. D. , Lee Hosun , Park S. J. , Jang J. , Lee Soonil
Published: September 2002

We used spectroscopic ellipsometry to characterize four different microcrystalline silicon (μc-Si) films, which were fabricated by crystallizing a-Si:H films predeposited on glass substrates using solid phase crystallization (SPC), excimer laser annealing (ELA), Ni induced silicide-mediated crystallization (Ni-SMC), and field enhanced silicide-mediated crystallization (FESMC) method, respectively. A linear regression analysis, which took the effective dielectric function of μc-Si layer into account using effective medium approximation, showed that all these films were homogeneous throughout their thickness except the oxide overlayers, and completely crystallized regardless of the crystallization method. In our linear regression analysis, the complex dielectric function of silicon microcrystallites was represented by the Adachi model dielectric function (MDF) [T. Suzuki and S. Adachi, Jpn. J. Appl. Phys., Part1 32, 4900 (1993)], and the broadening parameters of the critical points (CPs) in MDF were allowed to vary. The dielectric function of silicon microcrystallites showed systematic broadening and shrinking of the peak features corresponding to the E1 and E2 CPs, from which we concluded that the average microcrystallite size increased in the order of SPC, ELA, Ni-SMC, and FESMC μc-Si. The Raman spectra and the transmission-electron-microscopy images of these films also supported the idea of systematic variation in the microcrystallite size.
Lateral current transport path, a model for GaN-based light-emitting diodes: Applications to practical device designs
Authors: Kim Hyunsoo , Park Seong-Ju , Hwang Hyunsang , Park Nae-Man
Published: September 2002

An advanced model to explain the current spreading phenomenon of a conventional GaN-based light-emitting diode is presented. For this work, an equivalent circuit, consisting of the two lateral resistance components of the p-transparent electrode and the n-type layer is proposed. Theoretical calculations clearly reveal that the current density crowds near the n or p pads according to the device parameters and has an exponential behavior as a function of the lateral length. Based on these results, appropriate device parameters including the critical transparent-electrode thickness were determined, leading to a perfectly uniform current distribution. It was even possible to demonstrate the ideal device geometry without the need for a transparent electrode such as an interdigitated structure.
Effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals
Authors: Qiu Min
Published: September 2002

The validity of the two-dimensional approximation by the effective index method for heterostructure-slab-waveguide-based two-dimensional photonic crystals is tested against the full-vectorial three-dimensional finite-difference time-domain calculations. A good agreement over a wide frequency range is obtained for the band structures of two-dimensional photonic crystals in a low-index-contrast heterostructure. For high-index-contrast heterostructures, the effective index method is still valid, but only for much narrower frequency range.
Carbon site switching in carbon-doped GaAs
Authors: Mimila-Arroyo J. , Bland S. W. , Lusson A.
Published: September 2002

Carbon thermal stability in carbon-doped GaAs layers is studied. Epitaxial layers were grown by low-pressure metalorganic chemical vapor deposition extrinsically doped with an atomic carbon concentration around 1×1020 cm−3. The hole concentration is found to be a complex function of the annealing time, increasing from an initial value ∼7.2×1019 cm−3, to some intermediate value whereupon the hole concentration decreases before resuming its increase to a value consistent with the atomic concentration. The observed carrier loss and its subsequent recovery is explained by a double-site switch of one carbon from the CAs–Ga–CAs dimer. First, the carbon moves to an interstitial site Ci, where it behaves like a double donor, followed by a move to a more distant As substitutional site where it behaves as a normal shallow acceptor. This process allows to recover an additional hole concentration equal to the initial carbon dimer concentration. Both processes follow a first-order kinetics with different kinetic coefficients.
Anisotropic liquid crystal gels for switchable polarizers and displays
Authors: Ren Hongwen , Wu Shin-Tson
Published: September 2002

An anisotropic liquid crystal gel with low operating voltage, high contrast ratio, broad bandwidth, wide viewing angle, and fast response time was demonstrated. In the voltage-off state, the gel is highly transparent. When the gel is activated by an electric field, light scattering occurs for the polarization along the molecular axis. By incorporating a λ/4 film between the gel and a reflector, this reflective device is useful for modulating unpolarized light. Potential applications of such anisotropic gel as a broadband switchable polarizer, reflective display, and transflective display are emphasized.
Low-energy electron irradiation of fullerene films formed on Si(111)-(7×7) surfaces
Authors: Bolotov Leonid , Kanayama Toshihiko
Published: September 2002

C 60 films of 4–6 ML formed on Si(111)-(7×7) substrates were irradiated by field-emission (FE) electrons extracted at 15–80 V from probe tips of a scanning tunneling microscope (STM), and resulting evolution of film morphology was observed by the STM. At low extraction voltage, FE electrons stimulated polymerization of adjacent molecules and long-lasting migration of C60. At extraction voltage above ∼40 V, carbon spheroids less than 2 nm in height were created as a result of diffusion and coalescence of C60 fragments produced by electronic excitation.
Accurate quantum dynamics of a combustion reaction: Thermal rate constants of O(3P)+CH4(X 1A1)→OH(X 2Π)+CH3(X 2A2″)
Authors: Huarte-Larrañaga Fermı́n , Manthe Uwe
Published: September 2002

A quantum dynamics study of a polyatomic combustion reaction accurately considering all its internal degrees of freedom is presented. The thermal rate constants for the O(3P)+CH4(X 1A1)→OH(X 2Π)+CH3(X 2A2″) reaction is calculated and compared to experimental and approximate theoretical results. Good agreement with experiment is found and the reliability of some of the approximate approaches is confirmed.
Study of temperature dependence for the electron injection-induced effects in GaN
Authors: Chernyak Leonid , Burdett William , Osinsky Andrei
Published: September 2002

Electron-beam injection-induced increase of minority carrier diffusion length in p-type GaN was studied as a function of sample temperature ranging from 25 °C to 130 °C. It was found that the rate for diffusion length increase exponentially decays with increasing temperature. This decay was attributed to a temperature-activated release of electron-beam injected electrons trapped on Mg levels. The activation energy of these levels was found to be ∼178 meV. This is in good agreement with the previously reported position for Mg levels in the GaN band gap.
Near-infrared holographic recording with quasi-nonvolatile readout in LiNbO3:In,Fe
Authors: Zhang Guoquan , Tomita Yasuo , Zhang Xinzheng , Xu Jingjun
Published: September 2002

We investigate near-infrared photorefractivity and the dynamics of refractive index grating buildup and readout processes in reduced LiNbO3:In,Fe. High asymmetry in grating buildup and readout erasure rates is observed. This remarkable property makes the recorded grating quasinonvolatile during readout. The reason for the high asymmetry is explained qualitatively in terms of a multiple-defect-center model.
Wavelength demultiplexers based on the superprism phenomena in photonic crystals
Authors: Chung K. B. , Hong S. W.
Published: September 2002

We numerically analyze microscale wavelength-division-demultiplexing devices based on superprism phenomenon and waveguiding in photonic crystals. A few simple wavelength demultiplexers, which are composed of two photonic crystal structures that have different band structures and are in close contact with each other, are designed and simulated with the finite-difference time-domain method. It is found that depending on frequency, each demultiplexer diffracts incident waves in different directions, and couples them into different output photonic-crystal waveguides with low cross talk.
Structural, optical, and electrical properties of bulk single crystals of InAsxSb(1−x) grown by rotatory Bridgman method
Authors: Dixit V. K. , Bansal Bhavtosh , Venkataraman V. , Bhat H. L. , Subbanna G. N.
Published: September 2002

Radially-homogeneous and single-phase InAsxSb(1−x) crystals, up to 5.0 at. % As concentration, have been grown using the rotatory Bridgman method. Single crystallinity has been confirmed by x-ray and electron diffraction studies. Infrared transmission spectra show a continuous decrease in optical energy gap with the increase of arsenic content in InSb. The measured values of mobility and carrier density at room temperature (for x=.05) are 5.6×104 cm2/V s and 2.04×1016 cm−3, respectively.
Enhanced emission with angular confinement from photonic crystals
Authors: Enoch Stefan , Gralak Boris , Tayeb Gérard
Published: September 2002

We consider the emission of dipoles embedded in a photonic crystal. We demonstrate that it is possible to obtain an angular confinement of the emission (i.e., a large coherence area) together with an enhancement of the emitted power. A simple geometrical construction gives us a very comprehensive guideline. We illustrate the developed ideas with a structure working at the band edge of an expanded cubic photonic crystal and we take advantage of the large value of the density of states at these wavelengths. Then, it is shown that both directivity and total emitted power can be improved simultaneously without requiring defect modes.
Methyl group rotational tunneling splittings and spin conversion dynamics: p-chlorotoluene in cyclohexane
Authors: Pinsker M. , Friedrich J.
Published: September 2002

We performed spectral hole burning experiments in the UV with p-chlorotoluene as a probe in cyclohexane. A method is presented which allows for the determination of the rotational tunneling splitting in S0 and S1. The respective values are (117±4) GHz (3.90±0.13) cm−1 and (84±4) GHz (2.80±0.13) cm−1. From these numbers the rotational barriers and the respective rotational eigenvalues can be determined. Based on these results the spin conversion dynamics is reinterpreted as being governed by Orbach processes.
Presenilin-1 affects trafficking and processing of βAPP and is targeted in a complex with nicastrin to the plasma membrane
Authors: Kaether Christoph , Lammich Sven , Edbauer Dieter , Ertl Michaela , Rietdorf Jens , Capell Anja , Steiner Harald , Haass Christian
Published: September 2002

Amyloid β-peptide (Aβ) is generated by the consecutive cleavages of β- and γ-secretase. The intramembraneous γ-secretase cleavage critically depends on the activity of presenilins (PS1 and PS2). Although there is evidence that PSs are aspartyl proteases with γ-secretase activity, it remains controversial whether their subcellular localization overlaps with the cellular sites of Aβ production. We now demonstrate that biologically active GFP-tagged PS1 as well as endogenous PS1 are targeted to the plasma membrane (PM) of living cells. On the way to the PM, PS1 binds to nicastrin (Nct), an essential component of the γ-secretase complex. This complex is targeted through the secretory pathway where PS1-bound Nct becomes endoglycosidase H resistant. Moreover, surface-biotinylated Nct can be coimmunoprecipitated with PS1 antibodies, demonstrating that this complex is located to cellular sites with γ-secretase activity. Inactivating PS1 or PS2 function by mutagenesis of one of the critical aspartate residues or by γ-secretase inhibitors results in delayed reinternalization of the β-amyloid precursor protein and its accumulation at the cell surface. Our data suggest that PS is targeted as a biologically active complex with Nct through the secretory pathway to the cell surface and suggest a dual function of PS in γ-secretase processing and in trafficking.
Nuclear DNA helicase II is recruited to IFN-α–activated transcription sites at PML nuclear bodies
Authors: Fuchsová Beata , Novák Petr , Kafková Jarmila , Hozák Pavel
Published: September 2002

It is known that nuclear DNA helicase II (NDH II) links CREB-binding protein directly to RNA polymerase II holoenzyme, and that this interaction is essential for gene activation by CREB. Here, we report for the first time that some NDH II/RNA helicase A is a component of promyelocytic leukemia nuclear bodies (PML NBs). An autoimmune serum specific for PML NBs was identified and used in immunoprecipitation experiments. NDH II was present in the immunoprecipitates as shown by mass spectrometry and by immunoblotting. Immunofluorescence and ultrastructural studies showed that NDH II colocalizes with a small subset of PML NBs in control cells, however, colocalizes with practically all bodies in interferon-α–stimulated cells. After interferon stimulation, more PML NBs were found to contain newly synthesized RNA, as indicated by bromouridine incorporation. PML NBs also contain RNA polymerase II. The association of NDH II with PML NBs was transcriptionally dependent, and NDH II was present in all bodies with nascent RNA. Blocking of mRNA synthesis caused NDH II relocalization from nucleoplasm to nucleoli. Based on the data, we suggest that NDH II recruitment to PML NBs is connected with transcriptional regulation of interferon-α–inducible genes attached to PML NBs.
Distinct molecular and cellular contributions to stabilizing selectin-mediated rolling under flow
Authors: Yago Tadayuki , Leppänen Anne , Qiu Haiying , Marcus Warren D. , Nollert Matthias U. , Zhu Cheng , Cummings Richard D. , McEver Rodger P.
Published: September 2002

Leukocytes roll on selectins at nearly constant velocities over a wide range of wall shear stresses. Ligand-coupled microspheres roll faster on selectins and detach quickly as wall shear stress is increased. To examine whether the superior performance of leukocytes reflects molecular features of native ligands or cellular properties that favor selectin-mediated rolling, we coupled structurally defined selectin ligands to microspheres or K562 cells and compared their rolling on P-selectin. Microspheres bearing soluble P-selectin glycoprotein ligand (sPSGL)-1 or 2-glycosulfopeptide (GSP)-6, a GSP modeled after the NH2-terminal P-selectin–binding region of PSGL-1, rolled equivalently but unstably on P-selectin. K562 cells displaying randomly coupled 2-GSP-6 also rolled unstably. In contrast, K562 cells bearing randomly coupled sPSGL-1 or 2-GSP-6 targeted to a membrane-distal region of the presumed glycocalyx rolled more like leukocytes: rolling steps were more uniform and shear resistant, and rolling velocities tended to plateau as wall shear stress was increased. K562 cells treated with paraformaldehyde or methyl-β-cyclodextrin before ligand coupling were less deformable and rolled unstably like microspheres. Cells treated with cytochalasin D were more deformable, further resisted detachment, and rolled slowly despite increases in wall shear stress. Thus, stable, shear-resistant rolling requires cellular properties that optimize selectin–ligand interactions.
Elimination of the BKCa Channel's High-Affinity Ca2+ Sensitivity
Authors: Bao Lin , Rapin Anne M. , Holmstrand Ericka C. , Cox Daniel H.
Published: September 2002

We report here a combination of site-directed mutations that eliminate the high-affinity Ca2+ response of the large-conductance Ca2+-activated K+ channel (BKCa), leaving only a low-affinity response blocked by high concentrations of Mg2+. Mutations at two sites are required, the “Ca2+ bowl,” which has been implicated previously in Ca2+ binding, and M513, at the end of the channel's seventh hydrophobic segment. Energetic analyses of mutations at these positions, alone and in combination, argue that the BKCa channel contains three types of Ca2+ binding sites, one of low affinity that is Mg2+ sensitive (as has been suggested previously) and two of higher affinity that have similar binding characteristics and contribute approximately equally to the power of Ca2+ to influence channel opening. Estimates of the binding characteristics of the BKCa channel's high-affinity Ca2+-binding sites are provided.
The impact of human and organizational resources on small firm strategy
Authors: Edelman Linda F. , Brush Candida G. , Manolova Tatiana S.
Published: September 2002

Smaller less “glamorous” firms are more prevalent in the US economy than high‐technology companies. These small firms are known for their inability to erect barriers to imitation, making the development of competitive advantage difficult. In our paper, we study the relationship between firm resources and firm strategies. Based on the contention that the quality of a firm’s strategy cannot be judged independently of the firm resources on which it is based, we examine the relationship between firm resources and strategies in a cross‐section of over 250 small firms. Our findings indicate that small less glamorous firms should follow strategies that bring them closer to their customers, rather than innovation strategies that may be more appropriate for their high‐technology counterparts.
Bacterial expression and membrane targeting of the rat complement regulator Crry: A new model anticomplement therapeutic
Authors: Fraser Deborah A. , Harris Claire L. , Smith Richard A.G. , Morgan B. Paul
Published: September 2002

Inappropriate or unregulated activation of complement can contribute to pathology in inflammatory diseases. Previous studies have shown that soluble recombinant regulators of complement are effective in animal models and some human diseases. However, limitations include cost, rapid clearance, and unwanted systemic effects. To avoid some of these problems, bacterial expression of regulators has been optimized and methods for the addition of a membrane‐targeting moiety to the complement regulator developed. When administered directly to sites of inflammation, membrane‐targeted human regulators are retained and inhibit complement‐activation locally. To test the efficacy of membrane‐targeted complement regulators in vivo, we have undertaken the expression and membrane targeting of the rat‐complement regulator Crry. A soluble recombinant form of Crry, containing only the first four short consensus repeats, was expressed in a mammalian expression system and shown to be functional as a fluid phase regulator. To generate the quantities required for testing in vivo, Crry was expressed in bacteria and refolded successfully. Refolded protein had full‐complement regulatory activity in vitro. Attachment of a membrane address tag conferred membrane‐binding capacity and greatly increased complement regulatory function in vitro. This novel anticomplement agent can now be applied to rat models of arthritis and other inflammatory diseases.
Molecular dynamics simulations of alanine rich β‐sheet oligomers: Insight into amyloid formation
Authors: Ma Buyong , Nussinov Ruth
Published: September 2002

The aggregation observed in protein conformational diseases is the outcome of significant new β‐sheet structure not present in the native state. Peptide model systems have been useful in studies of fibril aggregate formation. Experimentally, it was found that a short peptide AGAAAAGA is one of the most highly amyloidogenic peptides. This peptide corresponds to the Syrian hamster prion protein (ShPrP) residues 113–120. The peptide was observed to be conserved in all species for which the PrP sequence has been determined. We have simulated the stabilities of oligomeric AGAAAAGA and AAAAAAAA (A8) by molecular dynamic simulations. Oligomers of both AGAAAAGA and AAAAAAAA were found to be stable when the size is 6 to 8 (hexamer to octamer). Subsequent simulation of an additional α‐helical AAAAAAAA placed on the A8‐octamer surface has revealed molecular events related to conformational change and oligomer growth. Our study addresses both the minimal oligomeric size of an aggregate seed and the mechanism of seed growth. Our simulations of the prion‐derived 8‐residue amyloidogenic peptide and its variant have indicated that an octamer is stable enough to be a seed and that the driving force for stabilization is the hydrophobic effect.
High Levels of Viral Replication Contrast with Only Transient Changes in CD4+and CD8+Cell Numbers during the Early Phase of Experimental Infection with Simian Immunodeficiency Virus SIVmnd-1 inMandrillus sphinx
Authors: Onanga Richard , Kornfeld Christopher , Pandrea Ivona , Estaquier Jerome , Souquière Sandrine , Rouquet Pierre , Mavoungou Virginie Poaty , Bourry Olivier , M'Boup Souleymane , Barré-Sinoussi Françoise , Simon François , Apetrei Cristian , Roques Pierre , Müller-Trutwin Michaela C.
Published: September 2002

Early events during human immunodeficiency virus infections are considered to reflect the capacity of the host to control infection. We have studied early virus and host parameters during the early phase of simian immunodeficiency virus SIVmnd-1 nonpathogenic infection in its natural host,Mandrillus sphinx. Four mandrills were experimentally infected with a primary SIVmnd-1 strain derived from a naturally infected mandrill. Two noninfected control animals were monitored in parallel. Blood and lymph nodes were collected at three time points before infection, twice a week during the first month, and at days 60, 180, and 360 postinfection (p.i.). Anti-SIVmnd-1 antibodies were detected starting from days 28 to 32 p.i. Neither elevated temperature nor increased lymph node size were observed. The viral load in plasma peaked between days 7 to 10 p.i. (2 × 106to 2 × 108RNA equivalents/ml). Viremia then decreased 10- to 1,000-fold, reaching the viral set point between days 30 to 60 p.i. The levels during the chronic phase of infection were similar to that in the naturally infected donor mandrill (2 × 105RNA equivalents/ml). The CD4+cell numbers and percentages in blood and lymph nodes decreased slightly (<10%) during primary infection, and CD8+cell numbers increased transiently. All values returned to preinfection infection levels by day 30 p.i. CD8+cell numbers or percentages, in peripheral blood and lymph nodes, did not increase during the 1 year of follow-up. In conclusion, SIVmnd-1 has the capacity for rapid and extensive replication in mandrills. Despite high levels of viremia, CD4+and CD8+cell numbers remained stable in the post-acute phase of infection, raising questions regarding the susceptibility of mandrill T cells to activation and/or cell death in response to SIVmnd-1 infection in vivo.
Sequential Localization of Two Herpes Simplex Virus Tegument Proteins to Punctate Nuclear Dots Adjacent to ICP0 Domains
Authors: Hutchinson Ian , Whiteley Alison , Browne Helena , Elliott Gillian
Published: September 2002

The subcellular localization of herpes simplex virus tegument proteins during infection is varied and complex. By using viruses expressing tegument proteins tagged with fluorescent proteins, we previously demonstrated that the major tegument protein VP22 exhibits a cytoplasmic localization, whereas the major tegument protein VP13/14 localizes to nuclear replication compartments and punctate domains. Here, we demonstrate the presence of a second minor population of VP22 in nuclear dots similar in appearance to those formed by VP13/14. We have constructed the first-described doubly fluorescence-tagged virus expressing VP22 and VP13/14 as fusion proteins with cyan fluorescent protein and yellow fluorescent protein, respectively. Visualization of both proteins within the same live infected cells has indicated that these two tegument proteins localize to the same nuclear dots but that VP22 appears there earlier than VP13/14. Further studies have shown that these tegument-specific dots are detectable as phase-dense bodies as early as 2 h after infection and that they are different from the previously described nuclear domains that contain capsid proteins. They are also different from the ICP0 domains formed at cellular nuclear domain 10 sites early in infection but, in almost all cases, are located in juxtaposition to these ICP0 domains. Hence, these tegument proteins join a growing number of proteins that are targeted to discrete nuclear domains in the herpesvirus-infected cell nucleus.
BCL-2 and BAX Protect Adult Mice from Lethal Sindbis Virus Infection but Do Not Protect Spinal Cord Motor Neurons or Prevent Paralysis
Authors: Kerr Douglas A. , Larsen Thomas , Cook Susan H. , Fannjiang Yih-Ru , Choi Eunkyung , Griffin Diane E. , Hardwick J. Marie , Irani David N.
Published: September 2002

Cellular proteins that regulate apoptotic cell death can modulate the outcome of Sindbis virus (SV) encephalitis in mice. Both endogenous and overexpressed BCL-2 and BAX proteins protect newborn mice from fatal SV infection by blocking apoptosis in infected neurons. To determine the effects of these cellular factors on the course of infection in older animals, a more neurovirulent SV vector (dsNSV) was constructed from a viral strain that causes both prominent spinal cord infection with hind-limb paralysis and death in weanling mice. This vector has allowed assessment of the effects of BCL-2 and BAX on both mortality and paralysis in these hosts. Similar to newborn hosts, weanling mice infected with dsNSV encoding BCL-2 or BAX survived better than animals infected with control viruses. This finding indicates that BCL-2 and BAX both protect neurons that mediate host survival. Neither cellular factor, however, could suppress the development of hind-limb paralysis or prevent the degeneration of motor neurons in the lumbar spinal cord. Infection of BAX knockout mice with dsNSV demonstrated that endogenous BAX also enhances the survival of animals but has no effect on paralysis. These findings for the spinal cord are consistent with earlier data showing that dying lumbar motor neurons do not exhibit an apoptotic morphology. Thus, divergent cell death pathways are activated in different target populations of neurons during neurovirulent SV infection of weanling mice.
STABLE MINIMAL HYPERSURFACES AND TANGENT CONE SINGULARITIES
Authors: MOORE HELEN
Published: September 2002

In this paper, I give an estimate on the dimension of the singular set of a tangent cone at infinity of a stable minimal hypersurface. Namely, let Mn ⊂ ℝn+1, n ≥ 2, be a complete orientable stable minimal immersion with bounded volume growth. Then n < 7 implies T∞(M) is smooth, and n ≥ 7 implies the singular set of T∞(M) has codimension at least seven.
HARMONIC MORPHISMS WITH ONE-DIMENSIONAL FIBRES
Authors: PANTILIE RADU
Published: September 2002

We study harmonic morphisms by placing them into the context of conformal foliations. Most of the results we obtain hold for fibres of dimension one and codomains of dimension not equal to two. We consider foliations which produce harmonic morphisms on both compact and noncompact Riemannian manifolds.

By using integral formulae, we prove an extension to one-dimensional foliations which produce harmonic morphisms of the well-known result of S. Bochner concerning Killing fields on compact Riemannian manifolds with nonpositive Ricci curvature.

From the noncompact case, we improve a result of R. L. Bryant[9] regarding harmonic morphisms with one-dimensional fibres defined on Riemannian manifolds of dimension at least four with constant sectional curvature. Our method gives an entirely new and geometrical proof of Bryant's result.

The concept of homothetic foliation (or, more generally, homothetic distribution) which we introduce, appears as a useful tool both in proofs and in providing new examples of harmonic morphisms, with fibres of any dimension.
QED-CAVITY MODEL OF MICROTUBULES IMPLIES DISSIPATIONLESS ENERGY TRANSFER AND BIOLOGICAL QUANTUM TELEPORTATION
Authors: MAVROMATOS NICK E. , MERSHIN ANDREAS , NANOPOULOS DIMITRI V.
Published: September 2002

We refine a QED-cavity model of microtubules (MTs), proposed earlier by two of the authors (N.E.M. and D.V.N.), and suggest mechanisms for the formation of biomolecular mesoscopic coherent and/or entangled quantum states, which may avoid decoherence for times comparable to biological characteristic times. This refined model predicts dissipationless energy transfer along such "shielded" macromolecules near room temperatures as well as quantum teleportation of states across MTs and perhaps neurons.
CROSSOVER FROM 3D TO 2D IN THE ELECTRONIC STRUCTURE OF MgB2-TYPE SYSTEMS
Authors: HUANG G. Q. , LIU M. , CHEN L. F.
Published: September 2002

Using the Stuttgart Full-potential Linearized Muffin-tin Orbital method, we study a crossover of the electronic structure of MgB 2 from three-dimensional (3D) to 2D by artificially increasing the lattice constant along the c-axis. With the inter-layer coupling decreased by increasing c, the density of states (DOS) at E F has a considerable growth; at the same time, the charge transfer from Mg plane to B plane decreases so that the hole density in the B plane increases. As c is increased to 4c0, the electronic structure exhibits 2D characteristic and a van Hove peak in the DOS appears. The E2g phonon frequency at Γ point and the electron–phonon coupling constant λ are estimated by using the frozen phonon method. The calculated results indicate that T c in MgB 2 could be further increased if the inter-layer coupling might be reduced.
ROBUST OBJECT MATCHING USING A MODIFIED VERSION OF THE HAUSDORFF MEASURE
Authors: WANG YAMING , BACIU GEORGE
Published: September 2002

The Hausdorff distance (HD) between planar sets of points is known to be an effective measure for determining the degree of resemblance between binary images. In this paper, we analyze the conventional HD measure and propose a new Robust HD (RHD) measure. The proposed RHD measure takes into account not only the location information of the edge points, but also other factors such as the total number of the edge points whose nearest neighbors are within a specified directed distance, spurious edge segments defined by a small number of points, outliers, and occlusions. Experimental results for both synthetic and real images show that the proposed RHD measure is more efficient than the conventional HD measure.
Sustained integrin ligation involves extracellular free sulfhydryls and enzymatically catalyzed disulfide exchange
Authors: Lahav Judith , Jurk Kerstin , Hess Oded , Barnes Michael J. , Farndale Richard W. , Luboshitz Jacob , Kehrel Beate E.
Published: September 2002

Studies have suggested a pivotal role for free sulfhydryls in platelet integrin function, and enzyme-mediated reduction of disulfide bonds on platelets has been implicated. The platelet fibrinogen receptor αIIbβ3 is the best-studied platelet integrin and serves as a model system for studying the structure-function relation in this family of adhesion receptors. The demonstration of free sulfhydryls on the exofacial domain of purified αIIbβ3, specifically in its activated conformation, prompted us to explore the potential for activation-dependent, enzymatically catalyzed thiol expression on intact platelets and the possible role of surface-associated protein disulfide isomerase (PDI) in αIIbβ3 ligation. Using the membrane-impermeant sulfhydryl blocker para-chloromercuriphenyl sulfonate, the inhibitor of disulfide exchange bacitracin, and the monoclonal anti-PDI antibody RL90, we examined fibrinogen binding to αIIbβ3 as well as ligation-induced allosteric changes in the conformation of αIIbβ3. We sought to distinguish the possible involvement of disulfide exchange in agonist-induced platelet stimulation from its role in integrin ligation. Analysis of the role of free thiols in platelet aggregation suggested a thiol-independent initial ligation followed by a thiol-dependent stabilization of binding. Flow cytometric analysis showed that sustained binding of fibrinogen, as well as expression of ligand-induced binding site epitopes and ligand-bound conformation, depended on free thiols and disulfide exchange. Expression of P-selectin was minimally affected, even with complete inhibition of αIIbβ3function. These data indicate that although agonist-induced platelet stimulation is independent of ecto-sulfhydryls, engagement of integrin αIIbβ3 on the intact platelet depends totally on their enzymatically catalyzed surface expression.
An Incarcerated Individual With Weight Loss and Interstitial Pulmonary Infiltrates
Authors: Kapoor Nilesh , Dietz Christina , Buettner Benjamin P.
Published: January 2024

A man with HIV had syncopal episodes and hypoxemia after recent exposure to SARS-CoV-2; computed tomography revealed diffuse bilateral pulmonary micronodular opacities, a 2.2-cm nodule in the lingula, and mediastinal and hilar lymphadenopathy. What is the diagnosis and what would you do next?
Unraveling Wavy ST Segments—An Unusual Case of Syncope
Authors: Yan Kimberly L. , Short Robert T. , Goldschlager Nora F.
Published: January 2024

This case report describes a patient in their 60s with gastroesophageal reflex disease who presented to the emergency department after loss of consciousness during dinner and daily intermittent chest discomfort.
Population-Based Trends in Complexity of Hospital Inpatients
Authors: Naik Hiten , Murray Tyler M. , Khan Mayesha , Daly-Grafstein Daniel , Liu Guiping , Kassen Barry O. , Onrot Jake , Sutherland Jason M. , Staples John A.
Published: January 2024

Importance

Clinical experience suggests that hospital inpatients have become more complex over time, but few studies have evaluated this impression.

Objective

To assess whether there has been an increase in measures of hospital inpatient complexity over a 15-year period.

Design, Setting and Participants

This cohort study used population-based administrative health data from nonelective hospitalizations from April 1, 2002, to January 31, 2017, to describe trends in the complexity of inpatients in British Columbia, Canada. Hospitalizations were included for individuals 18 years and older and for which the most responsible diagnosis did not correspond to pregnancy, childbirth, the puerperal period, or the perinatal period. Data analysis was performed from July to November 2023.

Exposure

The passage of time (15-year study interval).

Main Outcomes and Measures

Measures of complexity included patient characteristics at the time of admission (eg, advanced age, multimorbidity, polypharmacy, recent hospitalization), features of the index hospitalization (eg, admission via the emergency department, multiple acute medical problems, use of intensive care, prolonged length of stay, in-hospital adverse events, in-hospital death), and 30-day outcomes after hospital discharge (eg, unplanned readmission, all-cause mortality). Logistic regression was used to estimate the relative change in each measure of complexity over the entire 15-year study interval.

Results

The final study cohort included 3 367 463 nonelective acute care hospital admissions occurring among 1 272 444 unique individuals (median [IQR] age, 66 [48-79] years; 49.1% female and 50.8% male individuals). Relative to the beginning of the study interval, inpatients at the end of the study interval were more likely to have been admitted via the emergency department (odds ratio [OR], 2.74; 95% CI, 2.71-2.77), to have multimorbidity (OR, 1.50; 95% CI, 1.47-1.53) and polypharmacy (OR, 1.82; 95% CI, 1.78-1.85) at presentation, to receive treatment for 5 or more acute medical issues (OR, 2.06; 95% CI, 2.02-2.09), and to experience an in-hospital adverse event (OR, 1.20; 95% CI, 1.19-1.22). The likelihood of an intensive care unit stay and of in-hospital death declined over the study interval (OR, 0.96; 95% CI, 0.95-0.97, and OR, 0.81; 95% CI, 0.80-0.83, respectively), but the risks of unplanned readmission and death in the 30 days after discharge increased (OR, 1.14; 95% CI, 1.12-1.16, and OR, 1.28; 95% CI, 1.25-1.31, respectively).

Conclusions and Relevance

By most measures, hospital inpatients have become more complex over time. Health system planning should account for these trends.
Publication of Results of Registered Trials With Published Study Protocols, 2011-2022
Authors: Vorland Colby J. , Brown Andrew W. , Kilicoglu Halil , Ying Xiangji , Mayo-Wilson Evan
Published: January 2024

Importance

Publishing study protocols might reduce research waste because of unclear methods or incomplete reporting; on the other hand, there might be few additional benefits of publishing protocols for registered trials that are never completed or published. No study has investigated the proportion of published protocols associated with published results.

Objective

To estimate the proportion of published trial protocols for which there are not associated published results.

Design, Setting, and Participants

This cross-sectional study used stratified random sampling to identify registered clinical trials with protocols published between January 2011 and August 2022 and indexed in PubMed Central. Ongoing studies and those within 1 year of the primary completion date on ClinicalTrials.gov were excluded. Published results were sought from August 2022 to March 2023 by searching ClinicalTrials.gov, emailing authors, and using an automated tool, as well as through incidental discovery.

Main Outcomes and Measures

The primary outcome was a weighted estimate of the proportion of registered trials with published protocols that also had published main results. The proportion of trials with unpublished results was estimated using a weighted mean.

Results

From 1500 citations that were screened, 308 clinical trial protocols were included, and it was found that 87 trials had not published their main results. Most included trials were investigator-initiated evaluations of nonregulated products. When published, results appeared a mean (SD) of 3.4 (2.0) years after protocol publications. With the use of a weighted mean, an estimated 4754 (95% CI, 4296-5226) eligible clinical trial protocols were published and indexed in PubMed Central between 2011 and 2022. In the weighted analysis, 1708 of those protocols (36%; 95% CI, 31%-41%) were not associated with publication of main results. In a sensitivity analysis excluding protocols published after 2019, an estimated 25% (95% CI, 20%-30%) of 3670 (95% CI, 3310-4032) protocol publications were not associated with publication of main results.

Conclusions and Relevance

This cross-sectional study of clinical trial protocols published on PubMed Central between 2011 and 2022 suggests that many protocols were not associated with subsequent publication of results. The overall benefits of publishing study protocols might outweigh the research waste caused by unnecessary protocol publications.
Sibling Death in Childhood and Early Adulthood and Risk of Early-Onset Cardiovascular Disease
Authors: Huang Chen , Peng Jiahuan , Lee Priscilla Ming Yi , Wang Ce , Wei Kecheng , Liang Minhong , Qin Guoyou , Yu Yongfu , Li Jiong
Published: January 2024

Importance

Sibling death is a highly traumatic event, but empirical evidence on the association of sibling death in childhood and early adulthood with subsequent risk of incident cardiovascular disease (CVD) remains limited.

Objective

To evaluate the association between sibling death in the early decades of life and subsequent risk of incident early-onset CVD.

Design, Setting, and Participants

This population-based cohort study included 2 098 659 individuals born in Denmark from 1978 to 2018. Follow-up started at age 1 year or the date of the first sibling’s birth, whichever occurred later, and it ended at the first diagnosis of CVD, the date of death, emigration, or December 31, 2018, whichever came first. Data analyses were conducted from November 1, 2021, through January 10, 2022.

Exposures

The death of a sibling.

Main Outcomes and Measures

The outcome was early-onset CVD. Cox models were used to estimate hazard ratios (HRs) with 95% CIs.

Results

This study included 2 098 659 individuals (1 076 669 [51.30%] male; median [IQR] age at death of sibling, 11.48 [4.68-21.32] years). During the median (IQR) follow-up of 17.52 (8.85-26.05) years, 1286 and 76 862 individuals in the bereaved and nonbereaved groups, respectively, were diagnosed with CVD. Sibling death in childhood and early adulthood was associated with a 17% increased risk of overall CVD (HR, 1.17; 95% CI, 1.10-1.23; cumulative incidence in bereaved individuals, 1.96% [1.61%-2.34%]; cumulative incidence in nonbereaved individuals at age 41 years, 1.35% [1.34%-1.37%]; cumulative incidence difference: 0.61% [95% CI, 0.24%-0.98%]). Increased risks were also observed for most type-specific CVDs, in particular for myocardial infarction (HR, 1.66; 95% CI, 1.12-2.46), ischemic heart disease (HR, 1.52; 95% CI, 1.22-1.90), and heart failure (HR, 1.50; 95% CI, 1.00-2.26). The association was observed whether the sibling died due to CVD (HR, 2.54; 95% CI, 2.04-3.17) or non-CVD (HR, 1.13; 95% CI, 1.06-1.19) causes. The increased risk of CVD was more pronounced for individuals who lost a twin or younger sibling (HR, 1.25; 95% CI, 1.15-1.36) than an elder sibling (HR, 1.11; 95% CI, 1.03-1.20).

Conclusions and Relevance

In this cohort study of the Danish population, sibling death in childhood and early adulthood was associated with increased risks of overall and most type-specific early-onset CVDs, with the strength of associations varying by cause of death and age difference between sibling pairs. The findings highlight the need for extra attention and support to the bereaved siblings to reduce CVD risk later in life.
FDA approves first genetic test to help identify risk for OUD
Authors: Knopf Alison
Published: January 2024

On Dec. 19, 2023, the U.S. Food and Drug Administration approved the first test that uses DNA in assessing whether certain individuals may have an elevated risk of developing opioid use disorder (OUD). As part of a clinical evaluation, the AutoGenomics, Inc. AvertD test is intended to be used prior to first exposure to oral opioid pain medications in patients being considered for a 4–30‐day prescription for the treatment of acute pain, such as in patients scheduled to undergo a planned surgical procedure. “The AvertD test, a prescription‐use only genetic laboratory test for patients 18 years and older, is to be used only with patients who consent to the test and have no prior use of oral opioid analgesics,” said Jeff Shuren, M.D., J.D., director of the FDA's Center for Devices and Radiological Health. “The test is administered by a health care provider by swabbing the cheek of a patient to collect a DNA sample that will be used to determine if a patient has a combination of genetic variants that may be associated with an elevated risk of developing OUD. This information should be used as part of a complete clinical evaluation and risk assessment; it should not be used alone to make treatment decisions. The test is not intended to be used in patients being treated for chronic pain. AvertD may help patients who are concerned about being treated with an opioid for acute pain make better informed decisions.” As part of the approval order, AutoGenomic, Inc. must provide training to health care providers to help ensure appropriate use of the test and conduct a large post‐market study assessing device performance in patients, regularly reporting progress made toward completion of that study to the FDA. The primary risks associated with AvertD are false negative and false positive results.
A Conformable Holographic Sensing Bandage for Wound Monitoring
Authors: Zhang Yihan , Hu Yubing , Montelongo Yunuen , Hsu Mintin , Blyth Jeff , Jiang Nan , Yetisen Ali K.
Published: January 2024

Chronic wound monitoring can provide personalized pathophysiological information for wound management and treatment. Continuously monitoring the wound milieu via the holographic pH sensor can reflect the wound healing processes. However, the integration with wearable devices is hindered by its inherently restricted interrogation angle dependency within 5°. Herein, a ball bearing‐based double photopolymerization method is developed to fabricate holographic pH sensors with a broader interrogation angle range of 15°–60° in wound exudates. The fabricated holographic pH sensor is then integrated with the flexible ultrathin polyurethane substrate, which replays a total Bragg peak shift of approximately 150 nm with physiological pH changes from 7.00 to 8.75. The conformable holographic pH sensing bandages demonstrate the ability to quantify the pH value under various bending manipulations, simulating the mounting on the body surface. The reversibility in artificial wound exudate demonstrates the durability and capability of real‐time pH monitoring in the wound milieu with minimal effect on the replay wavelength. The addition of electrolytes, albumin, urea, uric acid, lactate, and glucose does not interfere with the readout over the physiological pH range of wound exudates. The obtained conformable holographic sensing bandage benefits the wound healing process monitoring through colorimetric interrogation at point‐of‐care (POC) settings.
Porous Composite‐Mediated Bimetallic Cluster POMs/Zr‐MOF for Catalytic Transfer Hydrogenation of Biomass‐Derived Aldehydes and Ketones
Authors: Han Yi‐Wen , Ye Lei , Gong Tian‐Jun , Lu Xue‐Bin , Fu Yao
Published: January 2024

Synergistic catalytic effects and metal node modulation are pivotal to the performance of multifunctional catalysts.We present a versatile strategy for constructing bimetallic M1M2 cluster catalysts (polyoxometalates (POMs)/Zr‐based metal‐organic frameworks (Zr‐MOF); M1 = Zr; M2 = W, V, Mo) by a microwave‐assisted in‐situ precoordination‐postmodification approach, which consisted of the grafting of POM single clusters onto Zr–O clusters of hierarchical porous composites (defective Zr‐MOF (HUiO‐66x)) and the modulation of metal nodes in Zr‐MOF. Hierarchical porosity and double active centers in the POMs/Zr‐MOF result in greater accessibility to catalytic sites and adjustable acid–base properties, thus providing opportunities for the catalytic transfer hydrogenation of biomass‐derived aldehydes/ketones. The synergistic acid–base couple sites (W6+–O2−–Zr4+) not only bridge hydrogen donors into the reaction system but also promote the dissociation of α‐C(sp3)‐H from isopropanol and subsequent hydrogen transfer to the activated carbonyl in furfural. Enhanced substrate adsorption and decreased activation barrier of the rate‐determining step are keys for the direct hydrogen transfer from carbonyl compounds to near‐quantitative corresponding alcohols via an eight‐membered‐ring transition state to achieving unprecedented low‐temperature catalytic performance over bimetallic Zr–W clusters. The proposed general method of bimetallic cluster catalysts reveals the roles of accessible metal modulation and synergistic catalytic centers toward specific catalysis.