cssi/SciSciGPT-SciSciNet huggingface dataset:
Extended voiding cystometry: technique and results of monitoring in patients with suprasacral spinal cord injury

Extended voiding cystometry was performed for 3–10 h at the natural filling rate of 20 patients with complete suprasacral spinal cord injury and detrusor hyperreflexia and vesicosphicter dyssynergia who had normal upper tracts. This technique provided documentation of the frequency, duration, and amplitude of and the change in the intercontraction pressure during multiple physiologic voiding cycles. The percentage of time occupied by contractile activity and that during which intravesical pressures were >40 cmH2O were also calculated. The detrusor activity in this patient group has not previously been reported. Although our patients demonstrated frequent (2.1 contractions/h) high-amplitude (56.8 cmH2O), long (4 min/contraction) contractions and spent substantial time (13.8% of the time monitored) in contractile activity that maintained intravesical pressures of >40 cmH2O (8.4%), they showed no evidence of upper tract disease. The five patients who underwent outlet procedures because of clinically problematic autonomic dysreflexia demonstrated a statistically significant postoperative decrease in contraction amplitude (P 40 cmH2O (P<0.05). Extended voided cystometry enabled the measurement of detrusor contractility patterns and resting intravesical pressures that resulted from physiologic filling rates over an extended period, therefore providing considerably more information about detrusor activity than do conventional cystometric techniques.
On the Synoptic-Scale Lagrangian Autocorrelation Function

A large set of 10-day, quasi-two-dimensional atmospheric trajectory model data is used to compute Lagrangian autocorrelation functions for horizontal velocity components and to determine their integral timescale TL. The objectives of the study are to investigate the seasonal, interannual, and altitudinal behavior of TL and to present the Lagrangian autocorrelation functions corresponding to synoptic-scale flow. Results indicate that the integral timescale TL ranges from 15 to 24 h, with values for the meridional velocity component that are 10%‐25% less than values for the zonal velocity component. The Lagrangian autocorrelation functions are modeled using Gaussian and second-order autoregressive autocorrelation models. The model fits to the observed autocorrelation functions were found to be of similar form to those determined for a 1-yr set of three-dimensional trajectory data, suggesting that these functions are robust with respect to synoptic-scale, tropospheric flow.
Osmoregulation of the african clawed frog. Xenopus laevis, in hypersaline media

Abstract o 1. Xenopus laevis were gradually acclimated to sodium chloride solutions up to 300 mM/l (60% SW). Plasma samples were analyzed for solute concentrations at all acclimation salinities. 2. Xenopus laevis experienced 50% mortality (LC50) in the range of 250–280 mM/l NaCl. This high salinity tolerance indicates that dispersal of this species in Southern California waterways will not be limited by brackish water. 3. Tolerance to loss of body weight in X. laevis during gradual acclimation to hypersaline media was approx. 35% of its original weight. 4. Plasma concentrations were found to be hyperosmotic to the media at all concentrations tested (100–300 mM/l NaCl). The primary solute responsible for the increased body fluid concentration was urea. 5. X. laevis were not capable of obtaining free water from soil, even at soil water potentials of less than 0·5 atmospheres pressure. Body fluid solutes of this species in soil show the same trend as when it is exposed to hypersaline media.
Standards for in Situ current measurement

Historically, current sensors have been calibrated and intercompared to determine their accuracy and to develop trust in the quality of their data collected. In a more mature technology, standards are established to quantify quality, trustworthiness, and accuracy of measurement. For current meters we do not have standards beyond physical standards of length and time upon which we can claim current meter quality and have relied instead on best practice and intercomparison to judge suitability and trustworthiness for various applications. The measurement of current is more difficult than measurement of scalars such as pressure or temperature, since, to begin with, velocity of fluid is a vector but also it has variability over small scales in space and time. Inherently, flow may be divided into mean (current), oscillatory (wave), and chaotic flow (turbulence). Thus, attributes of a current sensor for measurement of global transport of heat and momentum may be different from those of one to measure surface wave spectra, which may differ again from one to measure boundary layer stress.
Effect of microstructure on the electrical characteristics of sol-gel derived PZT thin films

The effects of the microstructure of PZT sol-gel thin films, processed using different solutions, on their material and electrical properties have been studied. The films have different degrees of preferred orientation of the perovskite crystals as well as different grain size. The material characteristics are evaluated using SEM micrographs and XRD. Correlation of these material properties with the electrical properties for both NVRAM and DRAM applications is made.
Critical Points of the Determinant of the Laplace Operator

Abstract The determinant of the Laplace operator, det Δ , is a function on the set of metrics on a compact manifold. Generalizing the work of Osgood, Phillips, and Sarnak on surfaces, we consider one-parameter variations of metrics of fixed volume in the conformal class of given metric. By calculating the derivative of −log(det Δ ) with respect to such variations, we find the condition for a metric to be a critical point of the determinant function. Homogeneous manifolds satisfy this condition, but we exhibit examples of locally homogeneous manifolds which are not critical points in dimensions ≥ 3. For 3-dimensional manifolds, we derive a formula for the second derivative of −log(det Δ ) with respect to such a variation, at a critical point. Using this formula, we show that the standard metric on the sphere S 3 and some flat metrics on three-dimensional tori are local maxima of the determinant function.
Non-coherent MIMO radar in a non-Gaussian noise-plus-clutter environment

The initial papers on MIMO radar have triggered a tremendous amount of research work recently. How the MIMO radar detector, previously designed for Gaussian noise, performs when the noise-plusclutter is non-Gaussian is still unknown. In this paper, we evaluate the detection performance of the Gaussian detector under the non-Gaussian noise-plus-clutter in a non-coherent MIMO radar system. Using the theory of Spherically Invariant Random Vectors (SIRVs), we study three non-Gaussian noise-plus-clutter models employing the K, Laplace, and Student-T distributions, respectively. Simulations are carried out for different numbers of antennas, SNRs and false alarm probabilities. The results show that non-Gaussian noise-plus-clutter has no impact on the diversity gain of a MIMO radar system although it degrades the detection performance in some other ways. We also verify some known results on the optimality of the Gaussian detector for SIRV noise-plus-clutter models, while showing this is not true for non-SIRV models.
The design and production of Ti-6Al-4V ELI customized dental implants

This paper addresses the production of customized Ti-6Al-4V ELI dental implants via electron beam melting (EBM). The melting of Ti-6Al-4V ELI powder produces implants with great biocompatibility, fi ne mechanical performance, and a high bone ingrowth potential. The EBM technology is used to produce one-component dental implants that mimic the exact shape of the patient’s tooth, replacing the traditional, three-component, “screw-like” standardized dental implants currently used. The new generation of implants provides the possibility of simplifying pre-insertion procedures leading to faster healing time, and the potential of better and stronger osseointegration, specifi cally through incorporating lattice structure design.
A Study of Joints Suitable for Lamina Emergent Mechanisms

One way to save space and reduce cost in a competitive environment is to use ortho-planar compliant mechanisms which can be made from sheets of material, or lamina emergent mechanisms (LEMs). One major challenge associated with LEM design, however, is creating joints with the desired motion characteristics, especially where complex spatial mechanism topologies are required. This paper presents some important considerations for designing joints for LEMs. A technique commonly used in robotics, using serial chains of revolute and prismatic joints to approximate the motion of complex joints, is presented for use in lamina emergent mechanisms. Important considerations such as linkage configuration and simple prototyping are also discussed.Copyright © 2008 by ASME
Trajectories in land use change around U.S. National Parks and challenges and opportunities for management

Most protected areas are part of a larger ecological system, and interactions with surrounding lands are critical for sustaining the species and ecological processes present within them. Past research has focused on how development rates around protected areas compare to development rates across a wider area as measured within varying sizes of buffer areas or at the county level. We quantified land use change surrounding the 57 largest U.S. National Parks in the contiguous United States for the period 1940 to the present and grouped the parks based on patterns of change. Land use was analyzed within the area considered essential to maintaining natural processes within each park, the protected-area centered ecosystem (PACE). Six variables were measured to determine the current level of development: population density, housing density, percentages of land with impervious surfaces, in agriculture, covered by roads, or in public land. Time series of population density, housing density, and land in agriculture were used to analyze changes over time. Cluster analysis was used to determine if patterns in major land use typologies could be distinguished. Population density within PACEs increased 224% from 1940 to 2000, and housing density increased by 329%, both considerably higher than national rates. On average, private land in PACEs contained a combined 24% exurban and rural housing density, and these increased by 19% from 1940 to 2000. Five distinct land use classes were identified, indicating that groups of parks have experienced differing patterns of development on surrounding lands. The unique management challenges and opportunities faced by each group are identified and can be used by managers to identify other parks to collaborate with on similar challenges. Moreover, the results show park managers how severe land use changes are surrounding their park compared to other parks and the specific locations in the surrounding landscapes that influence ecological function within the parks. This is the first effort to develop a ''typology'' of protected areas based on land use change in the surrounding ecosystem. Other networks of protected areas may find this methodology useful for prioritizing monitoring, research, and management among groups with similar vulnerabilities and conservation issues.
Characterization of spatial statistics of distributed targets in SAR data

A statistical approach to the analysis of spatial statistics in polarimetric multifrequency SAR data, which is aimed at extracting the intrinsic variability of the target by removing variability from other sources, is presented. An image model, which takes into account three sources of spatial variability, namely, image speckle, system noise, and the intrinsic spatial variability of the target or texture, is described. It is shown that the presence of texture increases the image variance-to-mean square ratio and introduces deviations of the image autocovariance function from the expected SAR system response. The approach is exemplified by sea-ice SAR imagery acquired by the Jet Propulsion Laboratory three-frequency polarimetric airborne SAR. Data obtained indicate that, for different sea-ice types, the spatial statistics seem to vary more across frequency than across polarization and the observed differences increase in magnitude with decreasing frequency.
Software pipelines in image processing

Abstract In an image processing software system, when one wishes to perform a sequence of operations on an image, temporary files are typically used to pass the data from one program to the next. Pipelines, as implemented by the UNIX operating system, are an alternative to temporary files. Both approaches are compared in an image processing environment and it is shown that pipelines reduce the amount of processor time and clock time required.
“Hey You! Just Stopping By to Say Hi!”: Communicating With Friends and Family on MySpace

The growing popularity of social networking sites prompted the qualitative analysis of two sources of public communication within a sample of 44 MySpace profiles created by emerging adult women majoring in human development and family studies. Six major themes emerged from the comments: (1) friendly greetings/inquiries, (2) expressions of affection/encouragement, (3) suggestion/confirmation of plans, (4) personal asides/inside jokes, (5) exchanges of information/news, and (6) entertainment. In their blogs the students focused on significant relationships, school and work obligations, and their own personal philosophies. The conceptual framework of emerging adulthood was used to better understand the identity explorations of these students.
Roles for NHERF1 and NHERF2 on the Regulation of C3a Receptor Signaling in Human Mast Cells

Background The anaphylatoxin C3a binds to the G protein coupled receptor (GPCR, C3aR) and activates divergent signaling pathways to induce degranulation and cytokine production in human mast cells. Adapter proteins such as the Na+/H+ exchange regulatory factor (NHERF1 and NHERF2) have been implicated in regulating functions of certain GPCRs by binding to the class I PDZ (PSD-95/Dlg/Zo1) motifs present on their cytoplasmic tails. Although C3aR possesses a class I PDZ motif, the possibility that it interacts with NHERF proteins to modulate signaling in human mast cells has not been determined. Methodology/Principal Findings Using reverse transcription PCR and Western blotting, we found that NHERF1 and NHERF2 are expressed in human mast cell lines (HMC-1, LAD2) and CD34+-derived primary human mast cells. Surprisingly, however, C3aR did not associate with these adapter proteins. To assess the roles of NHERFs on signaling downstream of C3aR, we used lentiviral shRNA to stably knockdown the expression of these proteins in human mast cells. Silencing the expression of NHERF1 and NHERF2 had no effect on C3aR desensitization, agonist-induced receptor internalization, ERK/Akt phosphorylation or chemotaxis. However, loss of NHERF1 and NHERF2 resulted in significant inhibition of C3a-induced mast cell degranulation, NF-κB activation and chemokine production. Conclusion/Significance This study demonstrates that although C3aR possesses a class I PDZ motif, it does not associate with NHERF1 and NHERF2. Surprisingly, these proteins provide stimulatory signals for C3a-induced degranulation, NF-κB activation and chemokine generation in human mast cells. These findings reveal a new level of complexity for the functional regulation of C3aR by NHERFs in human mast cells.
Cross-Validating Non-Gaussian Data

Abstract This article describes an appropriate way of implementing the generalized cross-validation method and some other least-squares-based smoothing parameter selection methods in penalized likelihood regression problems, and explains the rationales behind it. Simulations of limited scale are conducted to back up the semitheoretical analysis.
Functionalized semitelechelic poly[N-(2-hydroxypropyl)methacrylamide] for protein modification.

Semitelechelic poly[N-(2-hydroxypropyl)methacrylamide]s (ST-PHPMA) with different functional end groups, namely carboxyl, methyl ester, hydrazide, and amino groups, were prepared by chain transfer free-radical polymerization. 2,2‘-Azobisisobutyronitrile (AIBN) was used as an initiator and 3-mercaptopropionic acid, methyl 3-mercaptopropionate, 3-mercaptopropionic hydrazide, and 2-mercaptoethylamine were used as chain-transfer agents. The semitelechelic polymers have been characterized by end-group analysis, size-exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The effects of the concentrations of the mercaptans and the initiator on the molecular weight of the polymers have been investigated. The higher the concentration of mercaptan, the lower the molecular weight of ST-PHPMA. The concentration of initiator did not have a significant effect on the molecular weight of the semitelechelic polymers. The end groups of the ST polymer...
Regulation of Sister Chromosome Cohesion by the Replication Fork Tracking Protein SeqA

Analogously to chromosome cohesion in eukaryotes, newly replicated DNA in E. coli is held together by inter-sister linkages before partitioning into daughter nucleoids. In both cases, initial joining is apparently mediated by DNA catenation, in which replication-induced positive supercoils diffuse behind the fork, causing newly replicated duplexes to twist around each other. Type-II topoisomerase-catalyzed sister separation is delayed by the well-characterized cohesin complex in eukaryotes, but cohesion control in E. coli is not currently understood. We report that the abundant fork tracking protein SeqA is a strong positive regulator of cohesion, and is responsible for markedly prolonged cohesion observed at “snap” loci. Epistasis analysis suggests that SeqA stabilizes cohesion by antagonizing Topo IV-mediated sister resolution, and possibly also by a direct bridging mechanism. We show that variable cohesion observed along the E. coli chromosome is caused by differential SeqA binding, with oriC and snap loci binding disproportionally more SeqA. We propose that SeqA binding results in loose inter-duplex junctions that are resistant to Topo IV cleavage. Lastly, reducing cohesion by genetic manipulation of Topo IV or SeqA resulted in dramatically slowed sister locus separation and poor nucleoid partitioning, indicating that cohesion has a prominent role in chromosome segregation.
Free recall and organization as functions of paced or unpaced responding and presentation rate

Free recall and intertrial organization of unrelated words were assessed at presentation rates of ½, 1, 2, or 4 sec, with recall either paced at 2-sec intervals or unpaced. Total recall times were equated for the two response modes. Neither recall nor organization differed for paced vs unpaced responding. Recall and organization were higher at slower presentation rates, and the two performance measures were positively correlated.
Fos-like immunoreactivity and thirst following hyperosmotic loading in rats with subdiaphragmatic vagotomy

If receptors in the gut relay information about increases in local osmolality to the brain via the vagus nerve, then vagotomy should diminish this signaling and reduce both thirst and brain Fos-like immunoreactivity (Fos-ir). Water intake in response to hypertonic saline (i.p. or i.g., 1 M NaCl, 1% BW; i.g., 0.6 M NaCl, 0.5% BW) was reduced during 120 min in rats with subdiaphragmatic vagotomy (VGX) compared to sham-VGX rats. Brain Fos-ir was examined in response to both i.g. loads. After the smaller load, VGX greatly reduced Fos-ir in the supraoptic nucleus (SON) and the magnocellular and parvocellular areas of the paraventricular nucleus (PVN). Fos-ir in the subfornical organ (SFO) and nucleus of the solitary tract (NTS) was not affected. After the larger load, VGX significantly reduced Fos-ir in the parvocellular PVN and in the NTS, but not in the other regions. Thus, decreased water intake by VGX rats was accompanied by decreased Fos-ir in the parvocellular PVN after the same treatments, indicating a role for the abdominal vagus in thirst in response to signaling from gut osmoreceptors. The decreased water intake in the VGX group was not reflected as a decrease in Fos-ir in the SFO. Absorption of the larger i.g. load may have activated Fos-ir through more rapidly increasing systemic osmolality, thereby obscuring a role for the vagus at this dose in the SON and magnocellular PVN.
Problems in turbidite research: A need for COMFAN

Comparison of modern submarine fans and ancient turbidite sequences is still in its infancy, mainly because of the incompatibility of study approaches. Research on modern fan systems mainly deals with morphologic aspects and surficial sediments, while observations on ancient turbidite formations are mostly directed to vertical sequences. The lack of a common data set also results from different scales of observation. To review the current status of modern and ancient turbidite research, an international group of specialists formed COMFAN (Committee on Fans) and met in September 1982 at the Gulf Research and Development Company research facilities in Pennsylvania.
Evaluation of gas data from high-temperature fumaroles at Mount St. Helens, 1980–1982

Abstract The Mount St. Helens fumarole gases show linear composition trends during periods of noneruptive degassing between September 1980 and October 1981. The trends are characterized by increasing H2O and decreasing CO2 and sulfur. Maximum fumarole temperatures also show a linear decrease during this period. High-temperature fumarole gases collected from the crater and dome between September 1980 and July 1982 are all H2O-rich (> 90%) with 1–10% CO2 and small amounts of H2S, SO2, H2, CO, HC, and HF. Trace amounts of COS and S2 are present, and occasional observations of minor CH4 appear to result from contamination or low-temperature reactions in sample vessels. The O2 fugacities of the gases remain near Ni-NiO during cooling. The low sulfur content of the gases obviates the need for extensive gas-rock oxygen exchange to maintain fO2's near Ni-NiO. A detailed thermodynamic analysis of 50 gas samples collected between September 1980 and December 1981 led to improved compositions for 22 samples. The gases were initially in a state of equilibrium, but disequilibrium modifications from atmospheric oxidation of H2 and, to a lesser extent, CO occurred within the upper portions of the fumarole vents. The last temperatures of equilibrium for the fumarole gases range from 800°C to 650°C and are nearly always higher than the collection temperatures. No evidence was found of disequilibrium admixture of surface waters; if such modifications of the fumarole gases occurred, the water must have been added at depth and have reequilibrated with the other gas species at magmatic or near-magmatic temperatures. The highest quality analytical data are obtained by field gas chromatograph measurements and from caustic soda bottle samples. Samples collected in evacuated bottles or by pumping through double stopcock tubes tend to be severely deficient in sulfur due to post-collection reactions between H2S and SO2. It is also necessary to infer the water content of the latter samples.
STUDY OF A GENERALIZED FRAGMENTATION MODEL FOR SPRAYS

We study a mathematical model for sprays which takes into account particle break-up due to drag forces. In particular, we establish the existence of global weak solutions to a system of incompressible Navier–Stokes equations coupled with a Boltzmann-like kinetic equation. We assume the particles initially have bounded radii and bounded velocities relative to the gas, and we show that those bounds remain as the system evolves. One interesting feature of the model is the apparent accumulation of particles with arbitrarily small radii. As a result, there can be no nontrivial hydrodynamical equilibrium for this system.
Enhancement of α-lactalbumin-like activity in mammary explants from pregnant rats in the absence of exogenous prolactin

Abstract Mammary explants from pregnant rats showed a progressive increase in α-lactalbumin activity during culture with insulin, hydrocortisone and prolactin. Unexpectedly, culture with only insulin and hydrocortisone produced a similar rate of increase of α-lactalbumin-like activity, but this increase commenced about 24 hr later. The delay suggests that the enhanced activity effected by insulin and hydrocortisone is not a reflection of carry-over of endogenous mammotrophic hormones. Insulin plus hydrocortisone did not stimulate casein or fatty acid synthesis by pregnancy tissue, and did not enhance α-lactalbumin-like activity in virgin rat mammary explants. Enhancement of this activity by insulin plus hydrocortisone in pregnant tissue was constant over a wide range of glucocorticoid concentrations, but was inhibited by progesterone. Available evidence indicates that the active factor in extracts from insulin-hydrocortisone-explants is a heat-stable protein which is either α-lactalbumin itself, or another molecule with similar specifier properties.
Interaction of carbon tetrachloride with β-naphthoflavone-mediated cytochrome P450 induction in winter flounder (Pseudopleuronectes americanus)

The interaction between beta-naphthoflavone induction (BNF: 100 mg/kg) and carbon tetrachloride (CCl4; 1 ml/kg) hepatotoxicity was examined in the flounder. Treatment groups composed of control, BNF, CCl4, and BNF/CCl4 were compared in terms of cytochrome P450 isozyme content (LM4b; LM2), catalytic activity, isozyme distribution. SGOT-SGPT levels, and pathology. CCl4 administration resulted in significant reductions in both the constitutive P450 (LM2) and the BNF-inducible isozyme (LM4b) as well as elevations in SGPT and SGOT levels. The decline in LM4b isozyme content was reflected by stoichiometric decreases in ethoxyresorufin-O-deethylase activities. BNF/CCl4 coadministration was protective in part against CCl4 hepatotoxicity. Immunohistochemistry indicated that LM4b was diffusely distributed throughout the liver. These interactions have demonstrated a multiple P450 isozyme involvement, the protective nature of BNF against CCl4 hepatotoxicity in the flounder, the ability to maintain an inductive response in face of CCl4 coadministration, and the diffuse distributional pattern of LM4b in the flounder liver.
Evidence for single electron transfer in claisen condensation. The reaction of ethyl p-nitrobenzoate with the lithium enolate of pinacolone

Abstract The paramagnetic intermediate in the reaction of ethyl p-nitrobenzoate with the lithium enolate of pinacolone is shownto be on the reaction pathway for the formation of the condensation product, 4,4-dimethyl-1-(4-nitrophenyl)-1,3-pentanedione.
Envirogeochemical exploration for 'NORM' wastes: quadrupole inductively coupled plasma mass spectrometric measurements of thorium and uranium isotopes

Naturally occurring radioactive material consists of 238U, 235U and 232Th and series daughters; it is released into the environment from many anthropogenic sources. The use of quadrupole ICP-MS is well-suited to site investigations of releases of naturally occurring radioactive material through measurements of the ratios 232Th∶230Th, 230Th∶238U and 234U∶238U. Each ratio measurement may potentially indicate the contrast between the geochemical background and the affected environment. 232Th∶230Th was measured in samples prepared by fusion or selective extraction; Th was concentrated using TRU-Spec extraction resin and isotopic measurements were made with 5–10 µg Th. The precision is ≈1% (2σmean) and 10% for 232Th∶230Th of 1 000 and 100 000–200 000, respectively. Thorium isotopic measurements were applied to studies of accumulation of 230Th in phosphate-fertilized lawns. The ratio 230Th∶238U was determined via combining separate measurements of 230Th∶232Th and 232Th∶235U or 232Th∶238U; a 230Th∶238U precision of 1–2% (2σmean) is reported for a phosphate fertilizer sample. This 230Th∶238U measurement scheme requires no synthetic yield tracers, and is applied to studies of deposition of U mill tailings in an affected river basin. The ratio 234U∶238U was determined in natural waters following a two-stage extraction with Chelex 20 and UTEVA resins; a precision of ≈0.3–0.5% (2σmean) is attained for sample concentrates containing 15–25 µg U. 234U∶238U measurements are useful in distinguishing between dissolved U from natural weathering versus mining/milling sources.
Burn care: results of technical and organizational progress.

BURN CARE HAS IMPROVED MARKedly in the decades that have passed since the sad description quoted above. Of the 1.25 million individuals who are treated for burns in the United States each year, about 51000 require hospital admission. High-risk groups include infants and young children, elderly persons, and young people in industrial occupations. Care of serious burns progresses through 4 phases, which often overlap in time: (1) initial evaluation and resuscitation; (2) initial excision and biological closure; (3) definitive wound closure; and (4) rehabilitation, reconstruction, and reintegration (TABLE).
Quantum dot rolled-up microtube optoelectronic integrated circuit

A rolled-up microtube optoelectronic integrated circuit operating as a phototransceiver is demonstrated. The microtube is made of a InGaAs/GaAs strained bilayer with InAs self-organized quantum dots inserted in the GaAs layer. The phototransceiver consists of an optically pumped microtube laser and a microtube photoconductive detector connected by an a-Si/SiO2 waveguide. The loss in the waveguide and responsivity of the entire phototransceiver circuit are 7.96 dB/cm and 34 mA/W, respectively.
Sequential photon-counting statistics and maximum-likelihood estimation techniques for gaussian optical fields*

An expression for the probability density function for the arrival time of the Mth photoelectron (M = 1, 2, 3, …), as measured from an arbitrarily chosen origin of time, is derived for an arbitrary optical field. The expression is evaluated for the field of a single-mode laser and for the gaussian (thermal) field produced by scattering laser light from the surface of a rotating ground-glass disk. A procedure for finding the maximum-likelihood estimate of the mean field irradiance based on measurements of the arrival time of the Mth photoelectron is given. Results of actual experiments are discussed which indicate that, in the case of the gaussian field, the sequential-detection procedure requires less total observation time to determine an estimate of the mean field irradiance than more conventional fixed-sample-size techniques. The least amount of time to reach an estimate results if the sequential-detection procedure measures the arrival time of the first photoelectron.
Photophysical Properties of Ricin

The molar absorption coefficient of ricin in phosphate-buffered saline (PBS) at 279 nm was measured as (93,900+/-3300) L mol(-1) cm(-1). The concentration of ricin was determined using amino acid analysis. The absorption spectrum of ricin was interpreted in terms of 69% contribution from absorption by tryptophan residues and 31% contribution from absorption by tyrosine residues. The total dipole strength of the ricin band at 280 nm was determined to be (147+/-8) D2 and was consistent with the combined dipole strengths of 10 tryptophan ([11.7+/-1.0] D2) and 23 tyrosine ([1.4+/-0.2] D2) residues. The structure of ricin was used to determine the coupling of the tryptophan residues in ricin. The maximum interaction energy was found to be 424 cm(-1)/epsilon while the average interaction between any two pairs of tryptophan residues was approximately 18 cm(-1)/epsilon. In this study, epsilon is the dielectric constant inside the protein. The fluorescence from ricin, excited at 280 nm, was dominated by fluorescence from tryptophan residues suggesting the presence of energy transfer from tyrosine to tryptophan residues. The absorbance and fluorescence of ricin increased slightly when ricin was denatured in a high concentration of guanidine. Irreversible thermal unfolding of ricin occurred between 65 degrees C and 70 degrees C. (D=3.3364*10(-30) Cm, not SI unit, convenient unit for the magnitude of the electric dipole moment of molecules.).
Two-dimensional echocardiographic image texture analysis: Reduction of regional variability using polar coordinates

Abstract Factors inherent to the ultrasound imaging system can influence quantitative ultrasound image texture and may produce changes that mask or mimic those due to alterations in tissue structure. In this study, we assessed the effect of the method of image data acquisition and analysis on the variations in quantitative texture measures that occurred solely due to the position of a region of interest (ROI) within the field of view. When ROI's, which varied in range and azimuth within the image of a tissue equivalent phantom (of uniform composition), were assessed by conventional analysis of scan-converted (rectangular coordinate) data, over 50 percent of all texture measures showed significant differences. Pseudo polar analysis reduced the number of texture measures showing regional variation by 80 percent (p
Cellulose in Cyanobacteria. Origin of Vascular Plant Cellulose Synthase

Although cellulose biosynthesis among the cyanobacteria has been suggested previously, we present the first conclusive evidence, to our knowledge, of the presence of cellulose in these organisms. Based on the results of x-ray diffraction, electron microscopy of microfibrils, and cellobiohydrolase I-gold labeling, we report the occurrence of cellulose biosynthesis in nine species representing three of the five sections of cyanobacteria. Sequence analysis of the genomes of four cyanobacteria revealed the presence of multiple amino acid sequences bearing the DDD35QXXRW motif conserved in all cellulose synthases. Pairwise alignments demonstrated that CesAs from plants were more similar to putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and Nostoc punctiforme American Type Culture Collection 29133 than any other cellulose synthases in the database. Multiple alignments of putative cellulose synthases from Anabaena sp. Pasteur Culture Collection 7120 and N. punctiforme American Type Culture Collection 29133 with the cellulose synthases of other prokaryotes, Arabidopsis, Gossypium hirsutum , Populus alba × Populus tremula , corn ( Zea mays ), and Dictyostelium discoideum showed that cyanobacteria share an insertion between conserved regions U1 and U2 found previously only in eukaryotic sequences. Furthermore, phylogenetic analysis indicates that the cyanobacterial cellulose synthases share a common branch with CesAs of vascular plants in a manner similar to the relationship observed with cyanobacterial and chloroplast 16s rRNAs, implying endosymbiotic transfer of CesA from cyanobacteria to plants and an ancient origin for cellulose synthase in eukaryotes.
Modeling thermal-hydrological response of the unsaturated zone at Yucca Mountain, Nevada, to thermal load at a potential repository.

This paper presents a numerical study on the response of the unsaturated zone (UZ) system of Yucca Mountain to heat generated from decaying radioactive wastes emplaced at the proposed repository. The modeling study is based on the current thermal-hydrological (TH) mountain-scale model, which uses a locally refined 2D north-south cross section and dual-permeability numerical approach. The model provides a prediction of the mountain-scale TH response under the thermal-load scenario of 1.45 kW/m, while accounting for future climatic changes and the effects of drift ventilation. The TH simulation results show that ventilation of the repository drifts has a large impact on thermal-hydrologic regimes and moisture-flow conditions at the repository. In both cases, with and without ventilation, the TH model predicts dry or reduced liquid saturation near the drifts for over 1,000 years, during which liquid flux through the drifts is reduced to either zero or less than the ambient flux. Without ventilation, the model predicts higher temperatures at the repository, but no major moisture redistribution in the UZ except in the areas very near the heated drifts.
A technique for approximately maintaining constant plasma levels of intravenous drugs.

BACKGROUND There is increasing interest among anesthesiologists in the use of continuous infusion of intravenous drugs. The therapeutic effect of most drugs is a function of the concentration at the site of drug effect, which in turn is determined by the plasma concentration. Constant plasma concentrations can be maintained by computer-controlled infusion pumps. However, such equipment is not yet widely available and will be expensive. METHODS A technique is presented to enable the anesthesiologist to maintain approximately a desired plasma concentration after an arbitrary bolus dose by using a series of infusions with rates decreasing in a stepwise fashion. The algorithm is based on approximating the exact infusion needed to maintain the target plasma concentration by producing this concentration at discrete, specific times. Equations are derived for calculating the sequential rates of the infusion scheme. The equations assume linear pharmacokinetics, and the starting point for derivation of the equations is the assumption that the plasma concentration is given by the convolution of the drug infusion and the unit dose-response function. RESULTS The accuracy of the technique was assessed by simulating the infusion of fentanyl and midazolam. By using an infusion scheme of three steps, the error was no greater than 38% for fentanyl and no greater than 10% for midazolam. CONCLUSIONS Other than the assumption of linear kinetics, the algorithm is independent of pharmacokinetic models. Implementation does not require computer-based numerical analysis.
Occipital Intradiploic CSF Pseudocyst: An Unusual Complication of a Ventriculoperitoneal Shunt Malfunction

We report a rare and unique complication of ventriculoperitoneal (VP) shunt malfunction. A progressively expansile, CSF-containing occipital intradiploic cyst developed in a 15-year-old boy at the site of cystoperitoneal shunt draining a Dandy-Walker cyst; the shunt was placed when the boy was 4 years old. A proposed pathogenesis of the lesion is discussed.
High Affinity Receptor for Heat-Stable Enterotoxins (STa) on Rat Intestinal Epithelial Cells

Studies on the association of heat-stable enterotoxin (ST) produced by enterotoxigenic E. coli (ETEC) strain 431 with isolated rat intestinal epithelial cells and brush border membranes indicated that STas bind to a single class of specific high affinity receptor. Specific binding of radioiodinated ST (specific activity 600 to 900 Ci/mmole) was temperature dependent and reached a maximum between 5 and 10 minutes which correlated with increased activity of particulate guanylate cyclase. The rate of dissociation of 431 ST from either intestinal cells or brush border membranes was significantly less than the rate of association. The number of ST-specific receptors on rat intestinal cells determined by Scatchard analysis was 20,478± 6,185 per cell with an affinity constant (Ka) of 6.25 × 1011 L/M. The affinity constant determined for brush border membranes (Ka = 9.4 × 1011 L/M) agreed with the value obtained with whole cells. Binding experiments with 125I-431 ST and brush border membranes showed that purified STas from ETEC strains 667 (class 1 porcine enteropathogen), B-41 (bovine enteropathogen), and human strains 213 C2 (Mexico) and 153961–2 (Dacca, Bangladesh) exhibited similar patterns of competitive inhibition as homologous ST produced by strain 431 (class 2 enteropathogen). Further, purified LT (strain 286 C2) did not inhibit binding of 431 ST. Digestion of brush border membranes showed the ST receptor to be resistant to lipases and glycosidases but somewhat sensitive to proteases. The putative ST binding protein radiolabeled with 125I-431 ST was solubilized with sodium deoxycholate. One major radioactive band was detected by SDS-polyacrylamide gel electrophoresis followed by radioautography.
Clinical implications of the melatonin phase response curve.

In this issue of JCEM, the Burgess et al. report (1) on the melatonin phase response curve (PRC) has many clinical implications worthy of further discussion. A PRC is a mathematical tool established by convention because of its heuristic value for describing the direction and magnitude of phase shifts in the endogenous circadian pacemaker and its driven rhythms that result from applying a stimulus, such as melatonin or bright light. One of these driven rhythms results in a melatonin curve or profile; melatonin production by the pineal gland occurs almost exclusively at night in both diurnal and nocturnal species, resulting in a profile shaped like a square wave (2). Thus, the timing of melatonin production is governed by, and feeds back time-of-day information to, the pacemaker—which is primarily entrained to the light/dark cycle. [However, there is no negative feedback inhibition limiting the amount of melatonin produced (3).] Endocrinologists, as well as other clinicians, are primarily interested in: 1) the function of melatonin in humans as a neurohormone; 2) pathologies related to melatonin production; and 3) therapies resulting from melatonin supplementation. The jury is out as to whether or not there are significant melatonin disorders that are simply a matter of hyper- or hyposecretion. The medical implications of melatonin are best understood in a circadian context. Circadian disorders are numerous and important, and their treatment is informed by the melatonin (and light) PRCs.
Price adjustment and land valuation in the soviet agricultural reform: A view using Lithuanian farm data

Changes in land tenure in the U.S.S.R. require that agricultural producers pay for land use. The current distorted pricing system, plus the absence of functioning land markets, complicate land valuation and slow adoption of new property relations. In a well-functioning market economy, agricultural land would earn its marginal value product in agricultural production. This value can be measured empirically from production data and can serve as an appropriate initial value for users' fees. Copyright 1991 by Oxford University Press.
Cooperative helix stabilization by complex Arg-Glu salt bridges.

Among the interactions that stabilize the native state of proteins, the role of electrostatic interactions has been difficult to quantify precisely. Surface salt bridges or ion pairs between acidic and basic side chains have only a modest stabilizing effect on the stability of helical peptides or proteins: estimates are roughly 0.5 kcal/mol or less. On the other hand, theoretical arguments and the occurrence of salt bridge networks in thermophilic proteins suggest that multiple salt bridges may exert a stronger stabilizing effect. We show here that triads of charged side chains, Arg+–Glu−–Arg+ spaced at i,i+4 or i,i+3 intervals in a helical peptide stabilize alpha helix by more than the additive contribution of two single salt bridges. The free energy of the triad is more than 1 kcal/mol in excess of the sum of the individual pairs, measured in low salt concentration (10 mM). The effect of spacing the three groups is severe; placing the charges at i,i+4 or i,i+3 sites has a strong effect on stability relative to single bridges; other combinations are weaker. A conservative calculation suggests that interactions of this kind between salt bridges can account for much of the stabilization of certain thermophilic proteins. Proteins 2001;44:123–132. © 2001 Wiley-Liss, Inc.
Evaluation and Management of Secondary Hypertension

Most patients who present with elevated blood pressure (BP) will have essential (idiopathic) hypertension; extensive laboratory evaluation for secondary causes in these patients is low-yield and cost-prohibitive. However, identification of a secondary cause may often lead to a cure of the elevated BP or to a decrease in the number and/or doses of antihypertensive agents and a reduction in the long-term cardiovascular risks of hypertension. This chapter will focus on two important causes of secondary hypertension: renovascular stenosis and primary aldosteronism. Other causes of secondary hypertension include primary renal disease, oral contraceptive use, pheochromocytoma, Cushing’s syndrome, sleep apnea syndrome, and coarctation of the aorta. Clinical features which are suggestive of these disorders are given in Table 2.1.
The PEN project in Santa Monica: interactive communication, equality, and political action

An electronic communication system, especially if it is designed to accommodate open access via public terminals can allow information-disadvantaged groups (such as the homeless, and women) to exchange relevant information and engage in political action. The Public Electronic Network (PEN), a free computer-based messaging system available to Santa Monica, CA residents, allowed homeless and “homed” individuals to meet around the issue of homelessness. These meetings eventually led to collaborative political action to enable homeless individuals to more effectively seek employment. PEN also allowed female residents to engage in political discussion, and to form a female users' group to support female participation in the electronic networking system, and in the political community as a whole. © 1994 John Wiley & Sons, Inc.
Gastric accommodation and emptying in evaluation of patients with upper gastrointestinal symptoms

Abstract Background & Aims: Endoscopy-negative dyspepsia is a common symptom that often is difficult to define in pathophysiologic terms. The aim of this study was to assess the frequency of disordered gastric accommodation and emptying in patients referred with unexplained upper gastrointestinal symptoms. Methods: A computerized diagnostic index was used to identify all patients, 18–70 years old, who underwent single-photon emission computed tomography (SPECT) to assess gastric accommodation at Mayo Clinic Rochester over a 3-year period. Demographics, clinical features, and results of diagnostic testing, including scintigraphic gastric emptying, were extracted from the electronic record. Results: A total of 214 patients were identified; the primary clinical diagnoses were functional dyspepsia, postfundoplication syndromes, rumination syndrome, and diabetic dyspepsia. Gastric accommodation was impaired in 43% of the whole group: 47% of functional dyspepsia, 44% of postfundoplication syndromes, and 33% of diabetic dyspepsia. Delayed gastric emptying was most prevalent in diabetic dyspepsia, and was accelerated in postfundoplication syndromes groups. Thirty-seven percent of patients had abnormal gastric emptying. The highest prevalence of delayed gastric emptying was in the diabetic dyspepsia and accelerated gastric emptying in postfundoplication syndromes groups. Twenty-five percent of patients with normal gastric emptying had impaired accommodation. Upper-gastrointestinal symptoms were not different in groups based on gastric accommodation or emptying results. Conclusions: Impaired gastric accommodation is common in patients with unexplained dyspepsia. Symptoms alone cannot predict physiologic disturbances. These noninvasive tests identify single or combined pathophysiologic disturbances and may help to identify subgroups of patients as candidates for more selective pharmacotherapy in the future.