cssi/SciSciGPT-SciSciNet huggingface dataset:
Signal processing using surface acousto-optic interaction in LiNbO3

Abstract Signal processing functions such as convolution, correlation, and Fourier Transformation have been obtained in realtime using the efficient diffraction of laser light from acoustic surface waves progagating on LiNbO3. Different device configurations and detection schemes are discussed. Results are presented for the usual delay-line transducer configuration, as well as for an improved scheme which eliminates the problem of the reflection signal which is associated with this configuration. A discussion is given indicating the extension of the acousto-optical convolver to the generation of ambiguity functions and the correlation of a light amplitude distribution with an acoustic signal.
Biorefinery sustainability assessment

This article presents a comparative sustainability assessment of three biorefineries that produce liquid fuels used in current infrastructure. The three options considered are biochemical production of ethanol from grain and from cellulosic feedstocks and thermochemical production of Fischer-Tropsch diesel from biomass-derived syngas. These biorefineries were compared using numerous environmental, economic, and social metrics, with numerical values derived from a thorough review of recent literature. For each of the three biorefinery options, the metrics were not determined from a specific process design, but from a variety of different designs reported in literature. Where necessary, corn was selected as the feedstock for grain ethanol and switchgrass was selected for cellulosic ethanol and Fischer-Tropsch diesel. These sustainability metrics were used in an Analytic Hierarchy Process decision analysis to compare the sustainability of the different biorefineries. Thus, a new decision-making tool has been created in which the user can assign different weights to each category and its metrics. This tool was used to explore the influence of different weights, different market conditions, and uncertainties in the values of the metrics on the relative sustainability of the different options. Based on the results of this assessment, cellulosic ethanol biorefineries are modestly more sustainable than grain ethanol and Fischer-Tropsch diesel. Grain ethanol was favorable economically whereas Fischer-Tropsch diesel had the highest score on the societal metrics. © 2010 American Institute of Chemical Engineers Environ Prog, 2010
Survival in small cell lung carcinoma is independent of Bcl-2 expression.

Bcl-2 overexpression is a common event in small cell carcinomas (SCLC). The bcl-2 oncoprotein has a unique oncogenic role by inhibiting programmed cell death (apoptosis), resulting in tumorigenesis and chemoresistance. Forty-two cases of SCLC were stained immunohistochemically with bcl-2 monoclonal antibody (Biogenex, San Ramon, CA) after using an antigen retrieval step with citrate buffer. bcl-2 positivity was determined as detection of the oncoprotein in greater than 10% of noncrushed neoplastic cells. Twenty-five of 42 (60%) patients had extensive disease at presentation, 10 of 42 (24%) had limited disease, and 7 of 42 (16%) had disease localized to the lung. Twenty-four of 42 (57%) tumors were bcl-2 positive, and 18 of 42 (43%) tumors were bcl-2 negative. Follow-up in patients ranged from 7 days to 96 months (mean follow-up, 20 months). The median survival of patients with bcl-2-positive tumors was 11 months, as opposed to 13 months for bcl-2-negative tumors. There was no significant difference in median survival between bcl-2-positive and bcl-2-negative SCLC (log rank test, P = .2256). Using Cox's proportional hazards model, median survival in SCLC was determined to be independent of age at diagnosis, stage at presentation, therapeutic modality, and bcl-2 expression. bcl-2 expression does not significantly influence survival in SCLC.
Fast digital optical multiplication using an array of binary symmetric logic counters

Because of the lack of fast, accurate, and large dynamic range analog-to-digital converters (ADCs), optical implementation of the digital multiplication through analog convolution (DMAC) algorithm yields a slow digital multiplier. By replacing both the optical adder and ADC arrays by an optical combinatorial logic counter array, a new optical fast digital multiplication method is proposed. Compared to the existing optical DMAC scheme, the new method promises both higher processing speed and accuracy. A comparison of this and some of the other optical and electronic fast digital multiplication schemes is also presented.
Reconfigurable photonic crystal filters for multi-band optical filtering on a monolithic substrate

Many applications require the ability to image a scene in several different narrow spectral bands simultaneously. Absorption filters commonly used to generate RGB color filters do not have the flexibility and narrow band filtering ability. Conventional multi-layer dielectric filters require control of film thickness to change the resonant wavelength. This makes it difficult to fabricate a mosaic of multiple narrow spectral band transmission filters monolithically. This paper extends the previous work in adjusting spectral transmission of a multi-layer dielectric filter by drilling a periodic array of subwavelength holes through the stack. Multi-band photonic crystal filters were modeled and optimized for a specific case of filtering six optical bands on a single substrate. Numerical simulations showed that there exists a particular air hole periodicity which maximizes the minimum hole diameter. Specifically for a stack of SiO2 and Si3N4 with the set of filtered wavelengths (nm): 560, 576, 600, 630, 650, and 660, the optimal hole periodicity was 282 nm. This resulted in a minimum hole diameter of 90 nm and a maximum diameter of 226 nm. Realistic fabrication tolerances were considered such as dielectric layer thickness and refractive index fluctuations, as well as vertical air hole taper. It was found that individual layer fluctuations have a minor impact on filter performance, whereas hole taper produces a large peak shift. The results in this paper provide a reproducible methodology for similar multi-band monolithic filters in either the optical or infrared regimes.
A list of the trichostrongylid lungworms (Phylum Nematoda) and a key to the six genera.

In recent papers I have given, in relatively compact form, lists of the genera and species of metastrongylid lungworms; these publications are in turn summarized in a paper which follows (Dougherty, 1948). However, the trichostrongylid lungworms, constituting the subfamily Skrjabingylinae Skriabin, 1933, have not been completely treated, although in a recent work (Dougherty, 1945), in which certain lungworms were formally transferred from the Metastrongylidae to the Trichostrongylidae, the Skrjabingylin genera were listed without critical appraisal, and in the same paper the genus Crenosoma Molin, 1861, was reviewed in detail; subsequently the genus Dictyocaulus Railliet & Henry, 1907, has also been reviewed (by Dougherty, 1946).
An improved method for the detection of malignancy by proton nmr spectroscopy of plasma

Abstract The ratio of intensity (RI) of the plasma lipid methyl proton NMR resonance from two Carr-Purcell-Meiboom-Gill spectra acquired with a short (2.4 msec) and long (120 msec) pulse delay time is proposed to provide a potentially more sensitive and less variable marker of human malignancy than the linewidth parameter previously suggested ( E.T. Fossel, J.M. Carr, and J. McDonagh (1986) N. Engl. J. Med. 315 , 1369–1376). Linewidth and transverse (T2) relaxation data are presented which demonstrate that the observed correlation between methyl and methylene lipid linewidth and the methyl RI parameter arises from a combination of T2 differences and the relative amounts that fast- and slow-relaxing components contribute to the composite methyl resonance.
Media advertising effects on consumer perception of orthodontic treatment quality.

Abstract Objective: To determine the effect of media advertising on consumer perception of orthodontic treatment quality. Materials and Methods: A survey instrument was designed to evaluate factors influencing consumer selection of an orthodontist and consumer perception of different forms of media advertising (radio, television, newspaper, magazine, direct mail, and billboard) by orthodontic practices. The surveys were distributed by eight orthodontic offices in and around the Richmond, Virginia area. The survey return rate was 97%. Results: Respondents most often cited dentist and patient referrals as how they learned of the orthodontic practices they visited (50% to 57%). A caring attitude and good practitioner reputation were the top reasons influencing actual selection of an orthodontist (53% and 49%, respectively). Of respondents, 14% to 24% felt that advertising orthodontists would offer a lower quality of care than nonadvertising orthodontists. Newspaper, magazine, and direct mail advertisements w...
Chaperoning Histones during DNA Replication and Repair

Nuclear DNA is tightly packaged into chromatin, which profoundly influences DNA replication, transcription, repair, and recombination. The extensive interactions between the basic histone proteins and acidic DNA make the nucleosomal unit of chromatin a highly stable entity. For the cellular machinery to access the DNA, the chromatin must be unwound and the DNA cleared of histone proteins. Conversely, the DNA has to be repackaged into chromatin afterward. This review focuses on the roles of the histone chaperones in assembling and disassembling chromatin during the processes of DNA replication and repair.
Some results for the queues Mx /M/c and GIx/ G/c

We develop for the queue M^x/M/c an upper bound for the mean queue length and lower bounds for the delay probabilities (that of an arrival group and that of an arbitrary customer in the arrival group). An approximate formula is also developed for the general bulk-arrival queue GI^x/G/c. Preliminary numerical studies have indicated excellent performance of the results.
Targeted prefrontal cortical activation with bifrontal ECT.

Abstract The anatomical brain regions involved in the therapeutic and adverse actions of electroconvulsive therapy (ECT) are unknown. Previous studies suggest that bifrontal vs. bitemporal ECT differ in therapeutic efficacy and cognitive side effects. We therefore performed cerebral blood flow (CBF) imaging during bitemporal vs. bifrontal ECT-induced seizures to identify regions crucial for the differences between these treatments. Patients with major depression, undergoing bitemporal or bifrontal ECT, were studied. Ictal–interictal SPECT images were analyzed with statistical parametric mapping for bitemporal ( n =11 image pairs in 8 patients) and bifrontal ( n =4 image pairs in 2 patients) ECT-induced seizures to identify regions of ictal CBF changes. Bifrontal ECT was found to cause increases in CBF in prefrontal and anterior cingulate regions. Bitemporal ECT, however, caused CBF increases in the lateral frontal cortex and in the anterior temporal lobes. In bifrontal ECT, a greater increase in prefrontal activation, while sparing the temporal lobes, may result in a better therapeutic response and fewer adverse effects on memory than bitemporal ECT.
Training future hospitalists with simulators: a needed step toward accessible, expertly performed bedside procedures.

in this issue of the Journal, after 3years of training in all types of patient care units, residents of-ten count their accumulated experience on their ﬁngers andtoes. Such sparse experience hardly leads to expertise. Recog-nizing this pervasive lack of training the American Board ofInternal Medicine narrowed its certiﬁcation requirements forbedside procedures in 2006.
Storage and Equilibrium of Toroidal Magnetic Fields in the Solar Tachocline: A Comparison between MHD Shallow-Water and Full MHD Approaches

Recently Dikpati & Gilman have shown, using a shallow-water model of the solar tachocline that allows the top surface to deform, that a tachocline with the observed broad differential rotation and a strong toroidal field is prolate. A strong toroidal field ring requires extra mass on its poleward side to provide a hydrostatic latitudinal pressure gradient to balance the poleward curvature stress. In a parallel study using a different approach, Rempel, Schussler, & Toth have shown that such a latitudinal pressure gradient is found in a strongly subadiabatic stratification, whereas a weakly subadiabatic stratification leads to a complementary equilibrium state of the overshoot tachocline in which the magnetic curvature stress is balanced by a prograde rotational jet inside the toroidal ring. We show that the shallow-water model with height deformation is a first-order approach to the equilibrium state found by Rempel, Schussler, & Toth for a strongly subadiabatic stratification. We also show that the shallow-water model can be generalized to allow for the equilibrium state found for a weakly subadiabatic stratification by suppressing the shell deformation associated with the toroidal field and allowing the differential rotation to be modified.
The development and applications of the bacterial artificial chromosome cloning system.

The development of the Bacterial Artificial Chromosome (BAC) system was driven in part by the Human Genome Project as a means to construct genomic DNA libraries and physical maps for genomic sequencing. The BAC system is based on the well-characterized Escherichia coli F-factor, a low copy plasmid that exists in a supercoiled circular form in host cells. The structural features of the F-factor allow stable maintenance of individual human DNA clones as well as easymanipulation of the cloned DNA. BACs are currently used in a wide array of applications from genome sequencing to gene discovery. This paper describes the key elements in the development of the BAC system and its current notable applications.
The role of p53-mediated apoptosis as a crucial anti-tumor response to genomic instability: lessons from mouse models

Genomic instability is a major force driving human cancer development. A cellular safeguard against such genetic destabilization, which can ensue from defects in telomere maintenance, DNA repair, and checkpoint function, is activation of the p53 tumor suppressor protein, which commonly responds to these DNA damage signals by inducing apoptosis. If, however, p53 becomes inactivated, as is typical of many tumors and pre-cancerous lesions, then cells with compromised genome integrity pathways survive inappropriately, and the accrual of oncogenic lesions can fuel the carcinogenic process. Studies of mouse models have been instrumental in providing support for this idea. Mouse knockouts in genes important for telomere function, DNA damage checkpoint activation and DNA repair - both non-homologous end joining and homologous recombination - are prone to the development of genomic instability. As a consequence of these DNA damage signals, p53 becomes activated in cells of these mutant mice, leading to the induction of apoptosis, sometimes at the expense of organismal viability. This apoptotic response can be rescued through crosses to p53-deficient mice, but has dire consequences: mice predisposed to genomic instability and lacking p53 are susceptible to tumorigenesis. Thus p53-mediated apoptosis provides a crucial tumor suppressive mechanism to eliminate cells succumbing to genomic instability.
Imitators of severe preeclampsia

There are several obstetric, medical, and surgical disorders that share many of the clinical and laboratory findings of patients with severe preeclampsia-hemolysis, elevated liver enzymes, and low platelets syndrome. Imitators of severe preeclampsia-hemolysis, elevated liver enzymes, and low platelets syndrome are life-threatening emergencies that can develop during pregnancy or in the postpartum period. These conditions are associated with high maternal mortality, and survivors may face long-term sequelae. Perinatal mortality and morbidity also remain high in many of these conditions. The pathophysiologic abnormalities in many of these disorders include thrombotic microangiopathy, thrombocytopenia, and hemolytic anemia. Some of these disorders include acute fatty liver of pregnancy, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, and acute exacerbation of systemic lupus erythematosus. Because of the rarity of these conditions during pregnancy and postpartum, the available literature includes only case reports and case series describing these syndromes. Consequently, there are no systematic reviews or randomized trials on these subjects. Differential diagnosis may be difficult due to the overlap of several clinical and laboratory findings of these syndromes. It is important that the clinician make the accurate diagnosis when possible because the management and complications from these syndromes may be different. For example, severe preeclampsia and acute fatty liver of pregnancy are treated by delivery, whereas it is possible to continue pregnancy in those with thrombotic thrombocytopenic purpura-hemolytic uremic syndrome and exacerbation of systemic lupus erythematosus. This review focuses on diagnosis, management, and counseling of women who develop these syndromes based on results of recent studies.
Designing Nanosensors Based on Charged Derivatives of Gramicidin A

Detection of chemical processes on a single molecule scale is the ultimate goal of sensitive analytical assays. We recently reported the possibility to detect chemical modifications on individual molecules by monitoring a change in the single ion channel conductance of derivatives of gramicidin A (gA) upon reaction with analytes in solution. These peptide-based nanosensors detect reaction-induced changes in the charge of gA derivatives that were engineered to carry specific functional groups near their C-terminus.1 Here, we discuss five key design parameters to optimize the performance of such chemomodulated ion channel sensors. In order to realize an effective sensor that measures changes in charge of groups attached to the C-terminus of a gA pore, the following conditions should be fulfilled: (1) the change in charge should occur as close to the entrance of the pore as possible; (2) the charge before and after reaction should be well-defined within the operational pH range; (3) the ionic strength of th...
Mathematical and Computational Models of Oxidative and Nitrosative Stress

The importance of nitric oxide (NO), superoxide (O2-), and peroxynitrite (ONOO-), interactions in physiologic functions and pathophysiological conditions such as cardiovascular disease, hypertension, and diabetes have been established extensively in in vivo and in vitro studies. Despite intense investigation of NO, O2-, and ONOO- biochemical interactions, fundamental questions regarding the role of these molecules remain unanswered. Mathematical models based on fundamental principles of mass balance and reaction kinetics have provided significant results in the case of NO. However, the models that include interaction of NO, O2-, and ONOO- have been few because of the complexity of these interactions. Not only do these mathematical and computational models provided quantitative knowledge of distributions and concentrations of NO, O2-, and ONOO- under normal physiologic and pathophysiologic conditions, they also can help to answer specific hypotheses. The focus of this review article is on the models that involve more than one of the 3 molecules (NO, O2-, and ONOO-). Specifically, kinetic models of O2- dismutase and tyrosine nitration and biotransport models in the microcirculation are reviewed. In addition, integrated experimental and computational models of dynamics of NO/O2-/ONOO- in diverse systems are reviewed.
Expression of the HPV E7 oncoprotein mimics but does not evoke a p53-dependent cellular DNA damage response pathway.

Abstract Acute expression of the human papillomavirus E7 oncoprotein in preimmortal human fibroblasts induces changes in the abundances of multiple cellular regulatory proteins. These alterations include a destabilization of the retinoblastoma tumor suppressor protein pRB, stabilization of the tumor suppressor protein p53, and increases in the level of the cyclin-dependent kinase inhibitor p21 cip1 . Since the HPV E7 oncoproteins can interfere with several cell cycle checkpoints and similar alterations in the levels of pRB, p53, and p21 cip1 are also observed in a p53-dependent response to DNA damage, we investigated whether E7 expression triggers this signal transduction pathway. The results demonstrate that E7-mediated destabilization of pRB does not require p53 activity and is independent of the ability of E7 to induce apoptosis. Moreover, E7-mediated increases in p21 cip1 levels are largely p53-independent and involve stabilization of the p21 cip1 protein. In contrast the decreases in pRB expression in response to DNA damage involve transcriptional downregulation of RB gene expression.
Effect of film adhesion on tribological properties of silver-coated alumina

Abstract Soft metal films are seen as possible solid lubricants for sliding ceramics in high temperature environments. Ion bombardment of substrate and film can improve film adhesion and tribological properties of metal films deposited on ceramics. To provide a more detailed understanding of the relationship between measured adhesion strength, surface roughness, and wear performance of coatings, thin silver films were vapor deposited on smooth and roughened alumina substrates using 1 keV ion bombardment before and during deposition. A pull-type tester was used to measure the adhesion of films to the substrate. A ball-on-flat test machine was used to evaluate the wear of an uncoated alumina ball sliding on silver-coated substrates. Measurements of film adhesion and sliding wear, and a scanning electron microscopy examination of wear tracks, are reported. Ball wear on roughened surfaces was reduced by a factor of about 3 for poorly adhering coatings, but by a factor of about 130 for well-adhering coatings deposited after argon-oxygen sputter cleaning, compared with bare Al2O3. For films with the lowest wear, the silver coating wore off the tips of the asperities,but the film remained almost completely intact. For smooth flats, wear reductions by a factor of about 3 were obtained for well-adherent coatings.
A measurement-based analysis of multihoming

Multihoming has traditionally been employed by stub networks to enhance the reliability of their network connectivity. With the advent of commercial "intelligent route control" products, stubs now leverage multihoming to improve performance. Although multihoming is widely used for reliability and, increasingly for performance, not much is known about the tangible benefits that multihoming can offer, or how these benefits can be fully exploited. In this paper, we aim to quantify the extent to which multihomed networks can leverage performance and reliability benefits from connections to multiple providers. We use data collected from servers belonging to the Akamai content distribution network to evaluate performance benefits from two distinct perspectives of multihoming: high-volume content-providers which transmit large volumes of data to many distributed clients, and enterprises which primarily receive data from the network. In both cases, we find that multihoming can improve performance significantly and that not choosing the right set of providers could result in a performance penalty as high as 40%. We also find evidence of diminishing returns in performance when more than four providers are considered for multihoming. In addition, using a large collection of measurements, we provide an analysis of the reliability benefits of multihoming. Finally, we provide guidelines on how multihomed networks can choose ISPs, and discuss practical strategies of using multiple upstream connections to achieve optimal performance benefits.
A scalable soft spot analysis methodology for compound noise effects in nano-meter circuits

Circuits using nano-meter technologies are becoming increasingly vulnerable to signal interference from multiple noise sources as well as radiation-induced soft errors. One way to ensure reliable functioning of chips is to be able to analyze and identify the spots in the circuit which are susceptible to such effects (called "soft spots" in this paper), and to make sure such soft spots are "hardened" so as to resist multiple noise effects and soft errors. In this paper, we present a scalable soft spot analysis methodology to study the vulnerability of digital ICs exposed to nano-meter noise and transient soft errors. First, we define "softness" as an important characteristic to gauge system vulnerability. Then several key factors affecting softness are examined. Finally an efficient Automatic Soft Spot Analyzer (ASSA) is developed to obtain the softness distribution which reflects the unbalanced noise-tolerant capability of different regions in a design. The proposed methodology provides guidelines to reduction of severe nano-meter noise effects caused by aggressive design in the pre-manufacturing phase, and guidelines to selective insertion of on-line protection schemes to achieve higher robustness. The quality of the proposed soft-spot analysis technique is validated by HSPICE simulation, and its scalability is demonstrated on a commercial embedded processor.
Towards analytical convergence analysis of proportionate-type nlms algorithms

To date no theoretical results have been developed to predict the performance of the proportionate normalized least mean square (PNLMS) algorithm or any of its cousin algorithms such as the mu-law PNLMS (MPNLMS), and the e-law PNLMS (EPNLMS). In this paper we develop an analytic approach to predicting the performance of the simplified PNLMS algorithm which is closely related to the PNLMS algorithm. In particular we demonstrate the ability to predict the mean square output error of the simplified PNLMS algorithm using our theory.
Functional interactions between the proline-rich and repeat regions of tau enhance microtubule binding and assembly

Tau is a neuronal microtubule-associated protein that promotes microtubule assembly, stability, and bundling in axons. Two distinct regions of tau are important for the tau-microtubule interaction, a relatively well-characterized "repeat region" in the carboxyl terminus (containing either three or four imperfect 18-amino acid repeats separated by 13- or 14-amino acid long inter-repeats) and a more centrally located, relatively poorly characterized proline-rich region. By using amino-terminal truncation analyses of tau, we have localized the microtubule binding activity of the proline-rich region to Lys215-Asn246 and identified a small sequence within this region, 215KKVAVVR221, that exerts a strong influence on microtubule binding and assembly in both three- and four-repeat tau isoforms. Site-directed mutagenesis experiments indicate that these capabilities are derived largely from Lys215/Lys216 and Arg221. In marked contrast to synthetic peptides corresponding to the repeat region, peptides corresponding to Lys215-Asn246 and Lys215-Thr222 alone possess little or no ability to promote microtubule assembly, and the peptide Lys215-Thr222 does not effectively suppress in vitro microtubule dynamics. However, combining the proline-rich region sequences (Lys215-Asn246) with their adjacent repeat region sequences within a single peptide (Lys215-Lys272) enhances microtubule assembly by 10-fold, suggesting intramolecular interactions between the proline-rich and repeat regions. Structural complexity in this region of tau also is suggested by sequential amino-terminal deletions through the proline-rich and repeat regions, which reveal an unusual pattern of loss and gain of function. Thus, these data lead to a model in which efficient microtubule binding and assembly activities by tau require intramolecular interactions between its repeat and proline-rich regions. This model, invoking structural complexity for the microtubule-bound conformation of tau, is fundamentally different from previous models of tau structure and function, which viewed tau as a simple linear array of independently acting tubulin-binding sites.
Long-term outcomes and predictors in pediatric liver retransplantation

Historically, 9-29% of pediatric liver transplant recipients have required retransplantation. Although outcomes have improved over the last decade, currently published patient and graft survival remain lower after retransplant than after primary transplant. Data from liver retransplantation recipients at our institution between 1991 and 2013 were retrospectively reviewed. Kaplan-Meier estimates were used to depict patient and graft survival. Predictors of survival were analyzed using a series of Cox proportional hazards models. Predictors were analyzed separately for patients who had "early" (≤ 30 days after primary transplant) and "late" retransplants. Eighty-four patients underwent retransplant at a median time of 241 days. Sixty percent had late retransplants. At one, five, and 10 yr, actuarial patient and graft survival were 73%/71%, 66%/63%, and 58%/53%, respectively. Since 2002, patient and graft survival improved to 86%/86% at one yr and 93%/87% at five yr. While operative complications were a common cause of death after earlier retransplants, since 2002, infection has been the only cause of death. Significant morbidities at five-yr follow-up include renal dysfunction (15%), diabetes (13%), hypertension (26%), chronic rejection (7%), and PTLD (2%). Current survival after pediatric liver retransplantation has improved significantly, but long-term immunosuppressant morbidity remains an opportunity for improvement.
Glucosephosphate Isomerase Distribution During Oocyte Maturation and Early Embryologic Stages of the Mouse

The enzyme glucosephosphate isomerase (GPI) is of interest because of its role in glycolysis and its use as a cell marker in studies of embryogenesis utilizing chimeras. The distribution of GPI was determined in histologic sections of ovarian follicles and the tissues of early embryonic stages of the mouse. Antibodies of GPI were combined in an immunocytochemical procedure utilizing peroxidase-antiperoxidase to localize GPI in tissue sections. During follicular maturation, GPI is first detected in oocytes of small follicles and then in the granulosa cells of slightly larger follicles. The relative concentrations of GPI remain high in the granulosa cells adjacent to the oocyte as the follicles mature. GPI in the granulosa cells may play a role in providing the growing oocyte with low molecular weight energy sources. Within the conceptus, differences in GPI concentrations among tissues become apparent during the formation of the egg cylinder. The highest concentrations of GPI are in the embryonic ectoderm, the amniotic folds, the extraembryonic ectoderm, and the ectoplacental cone. These are areas of intense mitotic activity. The energy required for cell divisions during embryogenesis is derived from glycolysis, thus the high concentrations of GPI in these tissues correlates well with the cellular function.
About Hyperglycemia During Acute Stroke

To the Editor: Having completed a pilot clinical trial of aggressive hyperglycemia correction during acute cerebral infarction, we read with interest the recently published American Heart Association guidelines that include new suggestions for managing hyperglycemia during acute stroke.1 Although the guidelines clearly declare their lack of support by clinical trials (grade or level C), they suggest a relatively aggressive and ambiguous approach. The discussion section suggests that initiating treatment when glucose is >200 mg/dL …
A numerically efficient approach to metamaterial (MTM) modeling

Ever since the existence of negative refraction by metamaterial prisms was demonstrated by Pendry, Smith and others about a decade ago, the subject has received a tremendous amount of attention from many researchers around the world. A special class of MTMs, namely double negative or DNG type of artificially synthesized materials, has been used not only to design superlenses, but to also enhance the directivity of antennas, such as microstrip patch antennas (MPAs) [1–2]. In the process, the terms MTMs and DNGs have become almost synonymous; it is not uncommon to find them being used interchangeably with one another in the literature.
Colloidal Interactions between Particles with Tethered Nonpolar Chains Dispersed in Polar Media: Direct Correlation between Dynamic Rheology and Interaction Parameters

Colloidal interactions between particles dispersed in a liquid can be suitably tailored by modifying the surface chemistry of the particles. In the case of fumed silica particles, the surface can be systematically altered from hydrophilic to hydrophobic by replacing a portion of the original silanol (Si−OH) groups by nonpolar alkyl chains. In this study, we probe the effect of surface modification of fumed silica on their rheology and microstructure in polar media. Variables of interest include the length of the tethered alkyl chain and the extent of surface coverage. For the continuous phase, we examine a range of polyether liquids comprising different architectures and molecular weights. We find that when the alkyl chains are C8 or longer, and are attached at saturation levels, a dense nonpolar surface layer is formed on each silica unit. Such particles experience strong interactions in polar media, leading to the formation of a volume-filling network (gel). We show that these interactions arise as a re...
Animal Models of Hereditary Iron Transport Disorders

Animal models have long been recognized to be useful in understanding disorders of human iron homeostasis. Although the advent of molecular biology has vastly improved our understanding of the biochemistry and cellular biology of iron transport, studies in testtubes and tissue culture cells cannot lead to a total understanding of human iron disorders. This is because human iron disorders are invariably abnormalities of iron balance, resulting from defects in regulation of intestinal iron absorption or inappropriate distribution of iron among the tissues of the body. Thus, molecular studies cannot replace animal models in this area.
ADP-ribosylation factors: a family of ~20-kDa guanine nucleotide-binding proteins that activate cholera toxin

ADP-ribosylation factors (ARFs) comprise a family of ~20 kDa guanine nucleotide-binding proteins that were discovered as one of several cofactors required in cholera toxin-catalyzed ADP-ribosylation of Gsα, the guanine nucleotide-binding protein responsible for stimulation of adenylyl cyclase, and was subsequently found to enhance all cholera toxin-catalyzed reactions and to directly interact with, and activate the toxin. ARF is dependent on GTP or its analogues for activity, binds GTP with high affinity in the presence of dimyristoylphosphatidylcholine/cholate and contains consensus sequences for GTP-binding and hydrolysis. Six mammalian family members have been identified which have been classified into three groups (Class I, II, and III) based on size, deduced amino acid sequence identity, phylogenetic analysis and gene structure. ARFs are ubiquitous among eukaryotes, with a deduced amino acid sequence that is highly conserved across diverse species. They have recently been shown to associate with phospholipid and Golgi membranes in a GTP-dependent manner and are involved in regulating vesicular transport. (Mol Cell Biochem 138: 157–166, 1994)
Effect of oxygen-dependent antimicrobial systems on Legionella pneumophila.

Legionella pneumophila was susceptible to the antimicrobial action of oxygen metabolites generated by both the myeloperoxidase-H2O2-halide and the xanthine oxidase systems.
Structural definition and substrate specificity of the S28 protease family: the crystal structure of human prolylcarboxypeptidase

The unique S28 family of proteases is comprised of the carboxypeptidase PRCP and the aminopeptidase DPP7. The structural basis of the different substrate specificities of the two enzymes is not understood nor has the structure of the S28 fold been described. The experimentally phased 2.8 A crystal structure is presented for human PRCP. PRCP contains an α/β hydrolase domain harboring the catalytic Asp-His-Ser triad and a novel helical structural domain that caps the active site. Structural comparisons with prolylendopeptidase and DPP4 identify the S1 proline binding site of PRCP. A structure-based alignment with the previously undescribed structure of DPP7 illuminates the mechanism of orthogonal substrate specificity of PRCP and DPP7. PRCP has an extended active-site cleft that can accommodate proline substrates with multiple N-terminal residues. In contrast, the substrate binding groove of DPP7 is occluded by a short amino-acid insertion unique to DPP7 that creates a truncated active site selective for dipeptidyl proteolysis of N-terminal substrates. The results define the structure of the S28 family of proteases, provide the structural basis of PRCP and DPP7 substrate specificity and enable the rational design of selective PRCP modulators.
THE THERMAL BEHAVIOUR OF OSCILLATING GAS BUBBLES

Several aspects of the oscillations of a gas bubble in a slightly compressible liquid are discussed by means of a simplified model based on the assumption of a spatially uniform internal pressure. The first topic considered is the linear initial-value problem for which memory effects and the approach to steady state are analysed. Large-amplitude oscillations are studied next in the limit of large and small thermal diffusion lengths obtaining, in the first case, an explicit expression for the internal pressure, and, in the second one, an integral equation of the Volterra type. The validity of the assumption of uniform pressure is then studied analytically and numerically. Finally, the single-bubble model is combined with a simple averaged-equation model of a bubbly liquid and the propagation of linear and weakly nonlinear pressure waves in such a medium is considered.
Shareholders and managers: Who care more about corporate diversity and employee benefits?

We test two competing theories that explain a firm’s engagement in corporate diversity and employee benefits: socially responsible investment theory and management overinvestment theory. We find that publicly-traded companies with strong shareholder rights are more likely to promote women and/or minorities to the positions of CEO and board of directors in their organizations, conduct business with women- and/or minority-owned operations, and provide better family benefits to their employees than firms with strong management power. These findings indicate that the companies with strong shareholder rights engage more actively in internal aspects of CSR activities, which supports the socially responsible investment theory rather than the management overinvestment theory. Shareholders (i.e. institutional investors) tend to integrate their social goals (i.e. internal CSR issues) and financial goals into their investments. In response to these changes, managers should engage in the internal aspects of corporate social issues more aggressively as the agents of shareholders.
On the Asymptotic Size of Subvector Tests in the Linear Instrumental Variables Model

We calculate the asymptotic sizes of the subvector Anderson and Rubin (1949, AR) and Lagrange Multiplier (LM) tests in a linear instrumental variables model with two right hand side endogenous variables when the reduced form coefficient matrix is unrestricted. Under the assumption of conditional homoskedasticity we show that the subvector AR test has correct asymptotic size but that the asymptotic size of the subvector LM test is generally distorted. We provide size-corrected critical values for the subvector LM test.
Buckling of a Half Ice Sheet Against a Cylinder

This paper presents a theoretical analysis of the elastic buckling failure of a semi-infinite ice sheet moving against a cylindrical structure and computes the ice pressure associated with this failure mode. The basic equations are derived by applying the virtual work theorem to a plate on an elastic foundation, followed by a Fourier expansion of the variables in the circumferential coordinate. Numerical solutions are presented in dimensionless form. The results indicate that the boundary condition between the structure and the ice sheet is very important. The buckling pressure for an ice sheet with a fixed boundary condition is about four times as great as one with a frictionless boundary condition.
The cGMP-Phosphodiesterase β-Subunit Gene

Mutations in the protein-coding region of the gene encoding the (β-subunit of cyclic GMP-phosphodiesterase (β-PDE) cosegregate with retinal degeneration affecting humans1, mice2,3 and dogs4,5. Moveover, given that the exonic sequences are intact, the lack or the suboptimal expression of the β-PDE gene can cause alterations in phototransduction leading to photoreceptor functional and structural abnormalities. In light of the involvement of the β-PDE gene defects in the development of retinal disease, it is important to understand the events that regulate the expression of this gene in rod photoreceptors of the human retina.
Carbenicillin in Therapy of Systemic Infections due to Pseudomonas

A clinical trial of the semi-synthetic penicillin, carbenicillin, in the management of serious infections with gram-negative rods was carried out at the University of Colorado Medical Center. The overall results of this trial are reported elsewhere [1]. For the purposes of this symposium, analysis of results in specific infections might provide additional insight into the therapeutic capabilities and limitations of carbenicillin. This summary presents briefly the overall results of therapy of systemic infections with Pseudomonas, and also examines the results of therapy in patients with Pseudomonas infections of the lower respiratory tract and septicemia due to Pseudomonas. Twenty-nine patients with systemic infections with Pseudomonas were treated with carbenicillin alone, and 13 others were treated with carbenicillin and gentamicin. The dose of carbenicillin used varied from 150 mg/kg per day to 450 mg/kg per day for children and from 12 g/day to 30 g/day for adults. With few exceptions, the drug was administered intravenously on a 4-hr schedule. When used, the dose of gentamicin was 3-5 mg/ kg per day. Results of therapy were defined as follows. "Cured" indicates complete healing of the infected focus and eradication of Pseudomonas. "Im-
A new EEG artifact specific to digital acquisition.

PURPOSE To increase awareness in electroencephalographers of a new digital-specific artifact that could be falsely interpreted as epileptiform. METHODS Several examples of this artifact were discovered in clinical EEG recording. Examples of the clinical recording are presented using custom software to highlight the artifact. The underlying digital data were examined with standard hexadecimal editing software to verify the exact binary duplication error. RESULTS The artifact appears as repetitions of very brief intervals (50 milliseconds). In channels in which the signal has a large excursion (sharp slope) over this time frame, the repetition of a 50-millisecond interval could appear similar to polyspikes. In one instance, such a misinterpretation led to a technologist instructing a patient to remain in the clinic because of an "abnormality." CONCLUSIONS Artifacts that mislead the electroencephalographer are serious problems that can lead to erroneous affirmative diagnoses. The transition to digital acquisition brings the potential for new digital-specific errors. This report describes one such new digital artifact, discusses a conjecture for the stage of hardware where the artifact arises, suggests strategies for electroencephalographers to identify this artifact, and provides recommendations to clinical hardware vendors to avoid this error.
Local and regional resistance to fenvalerate in Psylla pyricola Foerster (Homoptera: Psyllidae) in western North America

Fenvalerate resistance was monitored in Psylla pyricola Foerster populations at 51 sites in Washington, Oregon, California, and British Columbia during early 1988. Resistance levels ranged from susceptible in an organic orchard in the Willamette Valley, OR, and at several other sites in Oregon and California, to highly resistant (> 100-fold compared with a susceptible strain) at several sites in central Washington. Generally, resistance levels were greater in the north than the south. In the Wenatchee and Yakima/Ellensburg, WA, areas, pyrethroid resistance was areawide, showing similar levels in both heavily treated and untreated orchards. In the Willamette Valley, OR, pyrethroid resistance was local and more consistent with the treatment histories of individual orchards. Factors influencing regional resistance appeared to be the species pool size of resistant and susceptible pear psylla, the intensity of spraying, and the unique host plant, life cycle, and dispersal attributes of this pest. Reasons for high regional resistance in central Washington and not in southerly areas are unknown, but this pattern is consistent with earlier patterns of insecticide resistance in pear psylla. The observed trends in fenvalerate resistance are discussed in relation to limiting resistance in pear psylla.
Jesuit Bark and Horseback Rides: Thomas Jefferson’s “Fits” as a Window into 18th Century Headache Care (P1.292)

OBJECTIVE: Thomas Jefferson’s headaches have been thoroughly described, but their treatment is less often considered. We use Jefferson’s headache therapy to gain insight into 18th century headache therapeutics, and to reexamine his cephalgia. BACKGROUND: Two hundred thirty-eight years ago, Philadelphia was a hotbed of political activity. The Second Continental Congress was about to convene, but in the spring of 1776, one of its most august representatives, Thomas Jefferson, suffered a bout of debilitating headaches. Jefferson’s “fits,” as he referred to them, have fascinated historians. They have alternately been identified as migraines, tension, or cluster headaches. Yet despite Jefferson’s scientific sophistication and record keeping, his headaches defy classification. Jefferson was less ambiguous regarding his headache therapy. His records and correspondence catalog his purchase of “bark” and cite therapies by Thomas Sydenham. Jefferson’s treatment provides insight into 18th century headache medicine. Likewise, an understanding of 18th headache therapeutics permits a novel approach to classifying Jefferson’s headache. METHODS: We searched PubMed for articles discussing Thomas Jefferson’s headaches. Additionally, we performed PubMed term searches for “Jesuit bark,” “Peruvian bark” and “quinine” in association with headache. Primary sources were obtained from public databases provided by monticello.org. RESULTS: Jefferson’s headache remedies included Jesuit bark, a quinine-containing product popularized by Sydenham in the 17th century. Additionally, Jefferson wrote of treating headaches by horseback riding, also attributed to Sydenham. Quinine, in the form of Jesuit bark, was a favorite headache remedy of an 18th century contemporary of Jefferson, Gerard Van Swieten, reported to be the first physician to describe cluster headaches. CONCLUSIONS: Jefferson’s Jesuit bark was a treatment advocated by contemporary physicians with headache expertise, notably in what is now known as cluster headache. While we are unable to conclusively identify Jefferson’s cephalgia, its treatment was consistent with 18th century cluster headache management. Disclosure: Dr. Luedke has nothing to disclose. Dr. Massey has nothing to disclose.