cssi/SciSciGPT-SciSciNet huggingface dataset:
Escherichia coli acid resistance: cAMP receptor protein and a 20 bp cis-acting sequence control pH and stationary phase expression of the gadA and gadBC glutamate decarboxylase genes

Acid resistance is an important feature of both pathogenic and non-pathogenic Escherichia coli. It enables survival in the acidic regions of mammalian gastrointestinal tracts and is largely responsible for the small number of bacteria required for infection/colonization. Three systems of acid resistance have been identified, the most efficient of which requires glutamic acid during pH 2 acid challenge. Three proteins associated with glutamate-dependent acid resistance have been identified. They are glutamate decarboxylase (encompassing two isozymes encoded by gadA and gadB) and a putative glutamate:gamma-amino butyric acid antiporter (encoded by gadC). The results confirm that the GadA and GadB proteins increase in response to stationary phase and low environmental pH. The levels of these proteins correspond to concomitant changes in gadA and gadBC mRNA levels. Fusions between lacZ and the gadA and gadBC operons indicate that this control occurs at the transcriptional level. Western blot, Northern blot and fusion analyses reveal that regulation of these genes is complex. Expression in rich media is restricted to stationary phase. However, in minimal media, acid pH alone can trigger induction in exponential or stationary phase cells. Despite this differential control, there is only one transcriptional start site for each gene. Expression in rich media is largely dependent on the alternate sigma factor sigma(S) and is repressed by the cAMP receptor protein (CRP). In contrast, sigma(S) has only a minor role in gad transcription in cells grown in minimal media. Deletions of the regulatory region upstream of gadA provided evidence that a 20 bp conserved region located 50 bp from the transcriptional start of both operons is required for expression.
Baseball as America/Baseball as America: Seeing Ourselves through Our National Game.

Baseball as America. National Baseball Hall of Fame Museum and Library, at the American Museum of Natural History, New York. March 16-August 18, 2002, traveling exhibition. Baseball as America: Seeing Ourselves through Our National Game. National Baseball Hall of Fame. Washington, DC: National Geographic, 2002. 330 pp.
Predicting properties of congestion events for a queueing system with fBm traffic

In packet networks, congestion events tend to persist, producing large delays and long bursts of consecutive packet loss resulting in perceived performance degradations. The length and rate of these events have a significant effect on network quality of service (QoS). The packet delay resulting from these congestion events also influences QoS. In this paper a technique for predicting these properties of congestion events in the presence of fractional Brownian motion (fBm) traffic is developed.
The initial hemorrhage from esophageal varices.

We conducted a prospective study of 321 patients with cirrhosis of the liver and esophageal varices with no history of bleeding to see whether a comprehensive analysis of their clinical features and of the endoscopic appearances of their varices could help to identify those at highest risk for bleeding. Varices were classified endoscopically as suggested by the Japanese Research Society for Portal Hypertension. Patients were followed for 1 to 38 months (median, 23), during which 85 patients (26.5 percent) bled. Multiple regression analysis (Cox's model) revealed that the risk of bleeding was significantly related to the patient's modified Child class (an index of liver dysfunction based on serum albumin concentration, bilirubin level, prothrombin time, and the presence of ascites and encephalopathy), the size of the varices, and the presence of red wale markings (longitudinal dilated venules resembling whip marks) on the varices. A prognostic index based on these variables was devised that enabled us to identify a subset of patients with a one-year incidence of bleeding exceeding 65 percent. The index was prospective validated on an independent sample of 75 patients with varices and no history of bleeding. We conclude that our prognostic index, which identifies groups of patients with one-year probabilities of bleeding ranging from 6 to 76 percent, can be used to identify candidates for prophylactic treatment.
LGN Blocks the Ability of NuMA to Bind and Stabilize Microtubules: A Mechanism for Mitotic Spindle Assembly Regulation

LGN is closely related to a Drosophila protein, Partner of inscuteable (Pins), which is required for polarity establishment and asymmetric cell divisions during embryonic development. In mammalian cells, LGN binds with high affinity to the C-terminal tail of NuMA, a large nuclear protein that is required for spindle organization, and accumulates at the spindle poles during mitosis. LGN also regulates spindle organization, possibly through inhibition of NuMA function, but the mechanism of this effect has not yet been understood. Using mammalian cells, frog egg extracts, and in vitro assays, we now show that a small domain within the C terminus of NuMA stabilizes microtubules (MTs), and that LGN blocks stabilization. The nuclear localization signal adjacent to this domain is not involved in stabilization. NuMA can interact directly with MTs, and the MT binding domain on NuMA overlaps by ten amino acid residues with the LGN binding domain. We therefore propose that a simple steric exclusion model can explain the inhibitory effect of LGN on NuMA-dependent mitotic spindle organization.
Nature of the heterogeneity in mispairing of reannealed middle-repetitive fern DNA.

The genome of the homosporous fern Thelypteris normalis contains a large middle-repetitive component, essentially a single second-order kinetic class, which exhibits heterogeneity in the precision of pairing of the reformed duplexes upon remelting. There are two possible models to explain this observed sequence heterogeneity. Either different families of the middle-repetitive class exhibit different degrees of sequence divergence and Tm reduction (inter familial heterogeneity), or else all are equally diverged, and the broad melt is the sum of thousands of equally broad melts for all the families (intra familial heterogeneity). To differentiate between these two hypotheses, iodinated Thelypteris DNA, reannealed through middle-repetitive C0t, was thermally fractionated on hydroxyapatite into low (65–75° C), medium (75–85° C), and high (85–95° C) thermal stability classes. When reannealed with excess cold DNA, each class remelted over its characteristic temperature range. C0t curves of these thermal fractions reannealed with cold driver demonstrated that all were from the middle-repetitive class. It was shown that these results were not due to G + C differences nor to artifacts of the labeling technique. Therefore it was concluded that, although all families consisted of approximately the same number of repeats, the families ranged from those with virtually no sequence divergence to those barely able to reanneal at the criterion used, in accordance with the model of inter familial heterogeneity. Though this model may have wide applicability to middle-repetitive DNAs, a different pattern appears to prevail in Selaginella, a heterosporous pteridophyte. Some evolutionary implications are discussed.
PERCUTANEOUS PATENT FORAMEN OVALE OR ATRIAL SEPTAL DEFECT CLOSURE IN IMMUNOCOMPROMISED PATIENTS

The safety of Patent foramen ovale (PFO) or atrial septal defect (ASD) percutaneous closure in immunosuppressed patients or with autoimmune disease is unknown. We attempted to determine if closure is safe in such patients. A prospective observational multicenter study was performed in 24 patients
Improved Electrical Measurement Techniques For The Characterization Of Microwave Field Effect Transistors

Improved methods are presented for the measurement and characterization of gallium arsenide (GaAs) microwave field effect transistors (FETs). An improved test fixture is discussed that is easier to use and more accurate than previous fixtures. A technique is presented that enables calibration at the input and output of the device under test (DUT) rather than the fixture connectors. A lumped element equivalent circuit model of the FET is used to predict electrical characteristics, amplifier gain, and minimum noise figure at higher-than-measurement frequencies and to obtain an improved physical understanding of the FET operation.
Metronidazole-Associated Aseptic Meningitis

SIR-Metronidazole is commonly used in the treatment of bacterial vaginosis and trichomonal vaginal infections, various anaerobic infections, intestinal giardiasis, and amoebiasis. We report a case of recurrent meningitis in a patient who received therapy with metronidazole. A 20-year-old woman presented to the emergency department with severe diffuse headache, fever, arthralgias, and myalgias of sudden onset. She had recently been evaluated for vaginal discharge, which contained clue cells without white blood cells, and a "whiff test" (10% KOH was added to the discharge sample) was positive. Therapy with metronidazole was prescribed for presumed bacterial vaginosis. She had taken a single 250-mg dose of metronidazole the morning of her admission to the hospital. Physical examination revealed a mildly toxic-appearing woman with a temperature of 101?F and a supple neck; the remainder of her examination did not reveal any abnormalities. Laboratory tests performed on admission revealed a white blood cell count of 21.4/mm3 (88% neutrophils, 7% band forms, 2% eosinophils, 1% monocytes, and 2% atypical lymphocytes). Analysis of CSF revealed a red blood cell count of 5/mm3 and a white blood cell count of 13/mm3 (8 neutrophils). Levels of protein and glucose in CSF were normal; findings of gram staining and results of culture were negative. The patient recovered uneventfully and was discharged on the third hospital day without treatment.
Perturbation of Cell pH Regulation by H2O2 in Renal Epithelial Cells

Abstract The purpose of these studies was to define the effect of oxidant stress on intracellular pH in renal tubular epithelial cells. Cell pH was therefore quantitated from the fluorescence ratio of 2′, 7′-bis- (2-carboxyethyl)-5(6)-carboxyfluorescein in the BSC-1 and opossum kidney (OK) established cell lines, both of which are known to be susceptible to oxidant injury. Exposure to 1 mM H 2 O 2 acidified cytosolic pH in both cell types, and this acidification reversed on withdrawal of the H 2 O 2 . Half-maximal acidification was seen at 10 μM H 2 O 2 . Effects on Na/H antiport were first measured as the recovery from an NH 4 Cl-pulse acid load: 1 mM H 2 O 2 inhibited Na/H anti-port-mediated pH recovery by approximately 40% in both cell types. H 2 O 2 substantially increased the rate of passive Na-independent H + flux in the OK cell but under the conditions used did not effect this flux in the BSC-1 cell. When both the Na/H antiport and Na-independent transport systems were blocked by perfusion with a 0-Na depolarizing buffer, the H 2 O 2 -induced acidification was totally abolished. Measured from the rate of H + appearance in the medium, H 2 O 2 decreased the rates of endogenous TV production in both cell types. As measured from the fluorescence of endocytosed fluorescein isothiocyanate-dextran, H 2 O 2 alkalinized lysosomes/late-endosomes, but at a rate much slower than the rate of cytosolic acidification. The results indicate that H 2 O 2 acidifies cell pH in these cell lines by inhibiting Na/H antiport, by accelerating the passive influx of TV, and to some extent by releasing H + from subcellular compartments. The acidification may have important effects in modulating the toxicity of H 2 O 2 .
Infinitely repeated contests: How strategic interaction affects the efficiency of governance

Contests over the scope and strength of regulation and governance are commonplace – and commonly repeated. The same players vie for the same government prize year after year: for example, environmental standards, government contracts, research grants, and public good provision. The open question is whether more rents are dissipated in repeated regulatory contests than onetime competitions. This question matters for regulation and governance because societies should design policies to waste the fewest scarce resources. According to some, the answer is “no”, but others say “yes”– more resources are wasted when people compete repeatedly for the same government prize. Herein, we use two game theoretic equilibrium concepts to help untangle the answer. Our results suggest non-myopic contestants are more likely to behave as partners than rivals – provided the context is relatively sterile. Several common complications help break up the tacit partnership, including a disparity in relative ability, a shrinking prize, and additional players.
Correlations between subject generated letter frequencies and observed frequencies in English

Five groups of 10 Ss each were asked to randomly generate 1000 single letters, 500 digrams, 334 trigrams, 250 tetragrams, and 200 pentagrams. Correlations between generated single letter frequencies and observed frequencies in English were high, ranging from.70 to.83, and it was concluded that Ss do not operate as random letter generators, but rather reflect quite precisely single letter frequencies as found in the language.
Orientation-Insensitive Methodology for Second Harmonic Generation. 1. Theory

The use of second harmonic generation as a means to probe either adsorption isotherms or the kinetics of adsorption/desorption is limited by the fact that the detected signal is dependent upon both surface coverage and molecular orientation. Thus, the second harmonic intensity must be tediously corrected if either the mean orientation angle or the width of the orientation distribution changes as a function of surface coverage. In this study, a new mathematical view of the second harmonic intensity as a function of excitation polarization is developed. This new approach predicts an experimental geometry that is relatively insensitive to molecular orientation, such that appropriate choice of the excitation polarization rotation angle allows for direct measurement of surface coverage. The theory is presented for the three common dominant hyperpolarizability tensor elements, βz‘z‘z‘, βz‘x‘x‘, and βx‘x‘z‘.
MONOSOMY X: A CHROMOSOMAL ANOMALY ASSOCIATED WITH YOUNG MATERNAL AGE

In spontaneous abortions, monosomy X is associated with young maternal age. The finding is not explained by low paternal age or by gravidity. The association may be intrinsic to pregnancies of young women or it may be due to experiences which are commoner in young women.
Empirical likelihood confidence intervals for M-functionals in the presence of auxiliary information

Abstract In this paper, we employ the method of empirical likelihood to construct confidence intervals for M-functionals in the presence of auxiliary information under a nonparametric setting. The modified empirical likelihood confidence intervals which make use of the knowledge of auxiliary information are asymptotically at least as narrow as the standard ones which do not utilize auxiliary information. For testing a hypothesis about a M-functional, the power of a test statistic based on the modified empirical likelihood ratio is larger than the one based on the standard empirical likelihood ratio. A simulation study is presented to demonstrate the performance of the modified empirical likelihood confidence intervals for small samples.
Breast cancer screening in women surviving Hodgkin disease.

Objective:To inform female Hodgkin disease (HD) survivors, younger than 35 at diagnosis, of their increased risk for breast cancer and encourage them to seek breast cancer screening.Methods:An evidence-based intervention, telephone counseling, was used in a pre-post test design, randomized trial wit
Development and evaluation of a generic tag array to detect and genotype noroviruses in water.

Abstract Noroviruses are the leading cause of nonbacterial gastroenteritis outbreaks in the United States, some of which are caused by the ingestion of contaminated water. Detection and genotypic characterization of noroviruses is commonly performed by reverse transcription-polymerase chain reaction (RT-PCR) followed by sequencing. However, sequencing of products amplified from environmental water samples is often hindered by the co-amplification of non-specific cDNA. To overcome this issue, a generic microarray was evaluated to genotype noroviruses by probe hybridization. RT-PCR amplicons are used in a single base extension (SBE) reaction where genotype-specific probes are labeled and then hybridized to an Affymetrix GeneChip ® GenFlex™ Tag Array for detection. Using a standardized, multiplex SBE reaction, genotyping of representative strains was accomplished through the identification of genotype-specific patterns of positive hybridization results. Furthermore, the SBE-GenFlex array method was successful in the genotype identification of noroviruses seeded into tap and Ohio River water samples. This study shows the utility of using a microarray to genotype noroviruses in complex environmental matrices.
Single-channel current recordings of acetylcholine receptors in electroplax isolated from the Electrophorus electricus Main and Sachs electric organs

Extensive chemical kinetic measurements of acetylcholine receptor-controlled ion translocation in membrane vesicles isolated from the electroplax ofElectrophorus electricus have led to the proposal of a minimum model which accounts for the activation, desensitization, and voltage-dependent inhibition of the receptor by acetylcholine, suberyldicholine, and carbamoylcholine. Comparison of chemical kinetic measurements of the dynamic properties of the acetylcholine receptor in vesicles with the properties of the receptor in cells obtained from the same organ and animal have been hampered by an inability to make the appropriate measurements withElectrophorus electricus electroplax cells. Here we report a method for exposing and cleaning the surface of electroplax cells obtained from both the Main electric organ and the organ of Sachs and the results of single-channel current recordings which have now become possible. The single-channel current recordings were made in the presence of either carbamoylcholine or suberyldicholine, as a function of temperature and transmembrane voltage. Both the channel open times and the single-channel conductance were measured. The data were found to be consistent with the model based on chemical kinetic measurements using receptor-rich membrane vesicles prepared from the Main electric organ ofE. electricus.
A functional and structural measurement of technology

Abstract This workshop on Technology Measurement has given me the opportunity to return to and critically review work that I had started 20 years ago. At that time I set out to generate a technological history of the digital computer industry[4]. The research was undertaken to develop and implement a methodology for following the evolution of a single technology—general purpose digital computers—in detail. The methodology was to trace the improvements in the technology to obtain a measure of “value” for new developments and to determine the “radicalness” of these developments. This methodology was developed to go beyond the existing research, which at that time consisted of authors' descriptions of what they had observed in the evolution of a technology. Such research consisted in part of authors giving their opinions on what they felt were key developments. Technological historians depended on opinions and expert judgements for determining “important” improvements or innovations and assessing their impact on the technology. The Functional/Structural Measurement that I proposed was intended to change all this by following the history of digital computers and using a precise technique which would flag all the innovations and then measure the value of each.
Implications of Functional Analysis Methodology for the Design of Intervention Programs

Functional analysis methodology is an assessment strategy that identifies sources of reinforcement that maintain problem behavior and prescribes individualized interventions that directly alter the conditions under which behavior occurs. In this article we describe the environmental determinants of problem behavior, methods for conducting functional analyses, and implications for the design of intervention programs.
Spatiotemporal detection of arterial structure using active contours

Abstract Active contour models (commonly called "snakes" ) have shown themselves to be a powerfuland flexible paradigm for many problems in image understanding. Active contour models arenow applied to the problem of detecting coronary blood vessels in cardiac angiography images,an important medical image understanding problem. Given two endpoints along a vessel, active contour models are used to find the vessel within a single angiography image. Snakes will also be employed to detect vessels across multiple frames, a task which involves computing localmeasures of interframe vessel motion. This is particularly important, since often the most usefulinformation to clinicians is found in the molion of a vessel across the cardiac cycle. 1 Introduction 1 . 1 Coronary Vasculature Detection In the field of medical image understanding, much attention has been given in recent years to theproblem of automatic detection and quantification of coronary vasculature in cardiac angiographicimages. These images, obtained by X-ray imaging of the heart during injection of a radio-opaquecontrast agent (see Figure 1), can show narrowed regions (stenoses) in the coronary arteries of
p53 alteration in regional lymph node metastases from prostate carcinoma: a marker for progression?

BACKGROUND Alterations of the p53 tumor suppressor gene are associated with advanced stage prostate carcinoma. The biologic significance of p53 nuclear accumulation in prostate cancer patients with regional lymph node metastases is uncertain. METHODS The authors investigated p53 alterations by immunohistochemistry in 220 lymph node positive patients who were treated with radical prostatectomy, bilateral pelvic lymphadenectomy, and androgen deprivation therapy between 1987–1992 at the Mayo Clinic. The mean follow-up was 6.3 years. Tumor volume of lymph node metastases was measured using the grid method. RESULTS p53 immunoreactivity was detected in 109 of 211 primary tumors (52%) and 83 of 144 matched regional lymph node metastases (58%); this expression was strongly concordant (correlation coefficient = 0.53; P = 0.0001). Overexpression of p53 protein in lymph node metastases was associated with distant metastasis free survival by univariate analysis (P = 0.03), but did not reach statistical significance by multivariate analysis (P = 0.07). Regional lymph node cancer volume was the single most important predictor of distant metastases after adjusting for Gleason score, DNA ploidy, and p53 expression. CONCLUSIONS The findings of the current study suggest that assessment of biologic changes (including p53 alterations in regional lymph node metastases) could be of value in the assessment of the biologic aggressiveness of prostate carcinoma, whereas p53 expression in the primary tumor does not appear to influence patient outcome. Cancer 1999;85:2455–9. © 1999 American Cancer Society.
Identification Error Bounds and Asymptotic Distributions for Systems with Structural Uncertainties

This work is concerned with identification of systems that are subject to not only measurement noises, but also structural uncertainties such as unmodeled dynamics, sensor nonlinear mismatch, and observation bias. Identification errors are analyzed for their dependence on these structural uncertainties. Asymptotic distributions of scaled sequences of estimation errors are derived.
Low resistance epitaxial CoSi/sub 2/-contacts for VLSI circuits

An investigation was conducted of the epitaxial growth of CoSi/sub 2/ on heavily ion implanted Si
Metal-binding properties of phytoferritin and synthetic iron cores

The non-ferrous metal-binding properties of phytoferritin from Glycine max were investigated, using microfiltration to quantitate the binding of aluminum, beryllium, cadmium and zinc to the holoprotein. All of the metals tested were bound by the protein with similar affinities ( K d ≈ 10 −6 M), although the smaller metals (Al and Be) were bound in much higher numbers than the heavier Cd or Zn. Since apoferritin binds these metals poorly or not at all, we investigated the role of the iron core in metal binding by preparing synthetic iron cores (as models of the holoferritin core) and studied the binding of the non-ferrous metals to these cores. Our results indicate that these synthetic cores can bind other metals in a manner entirely analogous to holoferritin, particularly when inorganic phosphate has been previously incorporated into the core. The ferrous-hydroxy-oxide core was shown to have a high affinity for the phosphate anion ( K d ≈ 2.5·10 −9 M), and beryllium binding was dramatically reduced when phosphate anion was omitted. Thus, our data would implicate the phosphate anion in the iron core of ferritin as being responsible for the high amount of non-ferrous metal-binding seen in the ferritin molecule. These data are consistent with our previous work on mammalian ferritin [18], and indicate that ferritin is capable of binding, and perhaps detoxifying, deleterious cations.
The impact of uterine leiomyomas: a national survey of affected women.

Objective We sought to characterize the impact of uterine leiomyomas (fibroids) in a racially diverse sample of women in the United States. Study Design A total of 968 women (573 white, 268 African American, 127 other races) aged 29-59 years with self-reported symptomatic uterine leiomyomas participated in a national survey. We assessed diagnosis, information seeking, attitudes about fertility, impact on work, and treatment preferences. Frequencies and percentages were summarized. The χ 2 test was used to compare age groups. Results Women waited an average of 3.6 years before seeking treatment for leiomyomas, and 41% saw ≥2 health care providers for diagnosis. Almost a third of employed respondents (28%) reported missing work due to leiomyoma symptoms, and 24% believed that their symptoms prevented them from reaching their career potential. Women expressed desire for treatments that do not involve invasive surgery (79%), preserve the uterus (51%), and preserve fertility (43% of women aged Conclusion Uterine leiomyomas cause significant morbidity. When considering treatment, women are most concerned about surgical options, especially women aged
Supporting Inclusion and Flourishing in the Religious and Spiritual Lives of People With Intellectual and Developmental Disabilities

Abstract An important aspect of supporting many people with intellectual and developmental disabilities to flourish involves providing meaningful opportunities to participate in the spiritual and r...
A polygynous nest of Vespula pensylvanica from California with a discussion of possible factors influencing the evolution of polygyny in Vespula.

A thriving, polygynous, and probably overwintered colony of the western yellowjacket,Vespula pensylvanica, was collected on 2 November 1994 in Riverside, southern California, and examined in detail. The colony had 14 combs, of combined area 1.30 m2 containing 55,704 small and 10,266 large cells. There were 17 functional, physogastric queens, 70 newly emerged non-reproductive queens, 7300 adult workers, 685 adult males, and c. 17,600 capped cells containing pupae or fully-fed larvae. Dissections of 200 workers showed that none had well-developed ovaries. Hypotheses for the rarity of polygyny inVespula are put forward and evaluated.
Pharmacokinetics of intravenously administered piperacillin in preadolescent children.

We studied the pharmacokinetics of piperacillin in 37 preadolescent children (mean age 52 months,range 1 month to 11 years) after 50 mg/kg IV doses. Pharmacokinetic parameters were determined after the initial dose in 18 instances and after subsequent doses in 32 instances. There were no significant differences between the initial doses and the subsequent doses in the plasma piperacillin concentrations at comparable times, the elimination rate constants, the elimination-phase plasma half-lives, the total body clearances, the apparent volumes of distribution, or the areas under the concentration curves. At the end of a 30-minute infusion of the drug, the plasma concentration was 166.2±42.2 mg/L (mean ± SD) and ranged from 91.6 to 268.3 mg/L. The mean half-life was 31.0±9.4 minutes. The half-life of piperacillin in children 1 to 6 months of age (47.2 minutes) was significantly longer than in older children (28.8 minutes) (P 2 ) was significantly lower than in the older children (130.8 ml/min/m 2 ) (P
Substitution of Leucine 28 with Histidine in theEscherichia coli Transcription Factor FNR Results in Increased Stability of the [4Fe-4S]2+ Cluster to Oxygen

To understand the role of the [4Fe-4S]2+ cluster in controlling the activity of the Escherichia coli transcription factor FNR (fumarate nitrate reduction) during changes in O2 availability, we have characterized a mutant FNR protein containing a substitution of Leu-28 with His (FNR-L28H) which, unlike its wild type (WT) counterpart, is functional under aerobic growth conditions. The His-28 substitution appears to stabilize the [4Fe-4S]2+ cluster of FNR-L28H in the presence of O2 because air-exposed FNR-L28H did not undergo the rapid [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion or concomitant loss in site-specific DNA binding and dimerization, which are characteristic of WT-FNR under these conditions. This increased cluster stability was not a result of His-28 replacing the WT-FNR cluster ligands because substitution of any of these four Cys residues (cysteine 20, 23, 29, or 122) with Ser resulted in [4Fe-4S]2+ cluster-deficient preparations of FNR-L28H. The Mossbauer spectra of FNR-L28H indicated that the coordination environment of the [4Fe-4S]2+ cluster did not differ from that of WT-FNR. Whole cell Mossbauer spectroscopy showed that aerobically grown cells overexpressing FNR-L28H had levels of the FNR species containing the [4Fe-4S]2+ cluster similar to those of cells grown under anaerobic conditions. Thus, the increase in cluster stability is sufficient to allow accumulation of the [4Fe-4S]2+cluster form of FNR-L28H under aerobic conditions and provides a reasonable explanation for why this mutant protein is functional under aerobic growth conditions. From these results, we present a model to explain how WT-FNR is normally inactivated under aerobic growth conditions.
Riparian ecosytems of semi-arid North America: Diversity and human impacts

Riparian ecosystems in the semi-arid West of North America are diverse but have many similarities. The mountainous landscape with wide range of latitude, longitude, and elevation offers diverse opportunities for streamside vegetation. All riparian ecosystems in the region are dependent on supplemental water, usually from the shallow, valley alluvial aquifer. Western riparian ecosystems provide several ecological services. They stabilize streambanks, trap sediment, improve water quality, and help control or modulate hydrologic processes. They function as habitat for many western animal species, serving as a small mesic island or strip within an arid landscape. They also serve as recreational sites for humans. Riparian systems are controlled by interacting hydrologic and geomorphic processes. Floods may alter river channel characteristics and the extent of riparian vegetation while enhancing recruitment of riparian species and recharging the alluvial water table. Geomorphic features, such as canyons and valleys, control the size of the riparian zone, as well as depth of the water table. Driving variables may differ from north to south, especially hydrology. For example, northern riparian zones are influenced by ice scour, while southern zones often have flash floods. Riparian systems occur along spatial and temporal gradients. Along elevational gradients, riparian vegetation may change from simple deciduous forests to mixed deciduous to coniferous and possibly alpine wetlands. Differences among channel, terrace, and upland plant communities decrease with increasing clevation as moisture stress decreases. Temporal gradients occur within a location in the riparian zone as early pioneer communities such as cottonwood/willow give way to late successional communities such as mesquite or sagebrush, often a consequence of sediment accumulation. Many similarities among western riparian ecosystems exist because several dominant genera (e.g.,Populus) are common throughout the West, and many geomorphic and hydrologic processes that influence riparian establishment are similar. Western riparian ecosystems have been greatly altered by human activity. Major factors include natural resource use, urbanization, alteration of stream flows through dam construction and ground-water withdrawal, modification of biotic conditions through grazing, agriculture, and introduction of non-native species, and alteration within watersheds. Better understanding of the ecology of western riparian ecosystems will increase potential for restoration and protection of remaining areas.
Part-Whole Practice of Movement Sequences

A 16-element movement sequence was taught under part-whole and whole-practice conditions. Participants (N = 18) produced a right-arm lever movement to sequentially presented target locations. The authors constructed part-whole practice by providing practice on only the 1st 8 elements on the 1st day of practice (100 repetitions of the 8-element sequence) and on all 16 elements on the 2nd day of practice (100 repetitions of the 16-element sequence). The whole-practice group practiced all 16 elements on both days (100 repetitions of the 16-element sequence per day). No differences in sequence structure or in movement duration of the 16-element sequence were noted on the retention test (Day 3). On transfer tests in which the 1st and last 8 elements were tested separately, however, the participants in the part-whole practice group performed more quickly than the participants in the whole-practice group, especially on the last 8 elements. Participants in the whole-practice group appeared to code the sequence so that it was relatively difficult to fully partition it into separate movements. Thus, on the transfer tests, there continued to be residual effects of the 8 elements that did not have to be produced but slowed down the rate of responding for the whole-practice group. That finding was not observed for the part-whole practice group.
Cardiovascular manifestations of pheochromocytoma

Pheochromocytomas are rare tumors that originate in chromaffin tissue and produce their distant variant effects by secretion of catecholamines, tending to mislead the emergency physicians to a wrong diagnosis. Therefore, we analyze the clinical cardiovascular manifestations in patients with pheochromocytoma to improve the diagnostic ability of the emergency physicians. All patients presenting to the Chang Gung Memorial Hospital between January 1993 and December 1997 with a final diagnosis of pheochromocytoma had their charts reviewed. The data of 25 patients including age, sex, adrenergic stimulation presentations, electrocardiographic changes, location of the tumor, and complications were analyzed. Hypertension was the most important major manifestation and fluctuation of blood pressure drew our attention to the possibility of pheochromocytoma. Six patients had abnormal electrocardiographic ST-T segment changes. Five of them had chest pain which prompted them to undergo coronary angiography before surgery, because acute coronary syndrome (unstable angina and acute myocardial infarction) was suspected initially. However, all of them turned out to have normal coronary arteries. Right-sided pheochromocytoma was found in three of these five patients. We should maintain high index of suspicion for pheochromocytoma in patients presenting with chest pain, fluctuating blood pressure, and ischemic electrocardiogram (ECG) changes despite any typical isoenzyme changes. Pheochromocytoma should also be included in the differential diagnosis of acute coronary syndrome because acute catecholamine secretion may induce chest pain and abnormal ECG changes mimicking an ischemic episode. The right-sided pheochromocytoma may present more striking electrocardiographic abnormalities and clinical manifestations.
Management of the Flexible Flat Foot in the Child: A Focus on the Use of Osteotomies for Correction

Pes planus, commonly referred as flat foot, is a combination of foot and ankle deformities. When faced with this deformity in children, the treating surgeon should use a systematic method for evaluation to distinguish normal variation from true pathology, as well as conditions that have a benign natural history versus those that may lead to significant disability if left untreated. Certain deformities will inevitably worsen and therefore require surgery. Common sense clearly supports the indication for a simple procedure, such as an arthroereisis or an osteotomy, performed in the young child as opposed to an arthrodesis in older adolescence or adulthood as the foot becomes more rigid. Such approaches and other issues are discussed in this article.
MULTIPERIODIC VARIABILITY IN MAGELLANIC CLOUD Be/X-RAY BINARIES

The long-term photometric behavior of seven Be–neutron star binaries in the Magellanic Clouds has been examined using MACHO and OGLE-II data. All show small periodic outbursts, which we associate with the periastron passage of the neutron star and its interaction with the Be star's disk. Five of these systems are known X-ray pulsars. The orbital periods we find for these pulsars fall near the "Corbet" relation for orbital versus pulse periods for Be/X-ray binaries. In four systems we detect a previously unrecognized type of quasi-periodic variation that is present between the orbital outbursts. These variations may be related to the rotation of the disk.
Using a hand-drawn sketch to control a team of robots

In this paper, we describe a prototype interface that facilitates the control of a mobile robot team by a single operator, using a sketch interface on a Tablet PC. The user draws a sketch map of the scene and includes the robots in approximate starting positions. Both path and target position commands are supported as well as editing capabilities. Sensor feedback from the robots is included in the display such that the sketch interface acts as a two-way communication device between the user and the robots. The paper also includes results of a usability study, in which users were asked to perform a series of tasks.
Role of discriminative stimuli in the formation of functional response classes

Abstract Chaining and association of responses with discriminative stimuli models were proposed to explain the development of covarying responses from different response classes. This experiment attempted to minimize the chaining model and provide empirical support for the discriminative stimuli model. A transfer of training paradigm involving secondary generalization was used with second-grade and kindergarten S s. Such conditions as association of responses with common discriminative stimuli, timing of performance of different responses to discriminative stimuli, order in which responses were associated with discriminative stimuli, and age and sex of S s were studied. Ruling out the chaining model proved impossible, since some of the S s, although not requested to do so, overtly chained the responses together. More S s who first associated verbal responses with the discriminative stimuli than S s who first associated motor responses transferred the untrained responses to the new discriminative stimuli. Second graders learned associations faster than kindergarteners, but an equivalent number of S s in each age group transferred.
Future Challenges for Ensemble Visualization

Simulating complex events is a challenge and often requires carefully selecting simulation parameters. As vast computation resources become available, researchers can run alternative parameter settings or simulation models in parallel, creating an ensemble of possible outcomes for a given event of interest. The visual analysis of ensembles is one of visualization's most important new areas and should greatly affect the field in the next few years. The goal is to develop expressive visualizations of an ensemble's properties to support scientists in this demanding parameter-space exploration.
Plasma Oxidase Assay for Screening of Myocardial Infarction

The availability of techniques such as surgical reperfusion, angioplasty, and thrombolysis for the treatment of acute myocardial infarction (AMI) has revived interest in seeking an early detectable biochemical marker diagnostic for AMI. Therefore, we investigated whether an unidentified oxidase that is released by activated neutrophils at the onset of AMI could be used as an early diagnostic assay. The conversion by plasma oxidase of 1 μM of adrenaline to 1 μM of adrenochrome represents the plasma oxidase activity (POA) of 1 U/L. Fifty patients suspected of having AMI, 40% of whose electrocardiograms were nondiagnostic for AMI, were admitted to the coronary care unit, and venous blood samples were obtained for determination of the POA and creatine phosphokinase-MB levels. Healthy volunteers (n = 12) served as control subjects, and 8 patients with pneumonia whose leukocyte counts were greater than 15,000 μL were included in the study. In those with AMI (n = 22), as determined by serial creatine phosphokinase-MB, the mean POA (± standard error of the mean) was 233 ± 13 U/L, and in those with angina and no AMI (n = 28) was 127 ± 5 U/L (P < 0.0001). In the control group, mean POA (± standard error of the mean) was 84 ± 5 U/L (control versus angina; s 0.01) and for those with infection was 214 ± 10 U/L. At admission, the creatine phosphokinase-MB was diagnostic for only 12 of the 22 patients with AMI (sensitivity rate of 54%), whereas in 21 of those patients, the POA values were diagnostic for AMI (sensitivity rate of 95%). Determination of POA may represent an alternative sensitive method to screen for AMI or ischemia in patients with anginal symptoms and no evidence of acute infection.
HYDRATION OF CONNECTIVE TISSUE AND TENDON ELASTICITY.

Abstract 1. The objective of this study was to determine the influence of hydration on elasticity of aging connective tissue. Involvement of tendon elasticity in age-produced joint stiffness was discussed in terms of the biophysical properties of hydrated rat-tail tendons. 2. Kinetic analysis of tendons swelling in water revealed that a dispersive factor (A) and a cohesive factor (B) relate the velocity of swelling (dW/dt) to tendon weight (W) by the equation: dW/dt = ks(A/W − BW). Aging and longitudinal stress reduced the maximum swelling ratio (W∞/W0) and hastened equilibration. Elongation of tendons occurred with hydration, and kinetic analysis showed that lengthening strongly depends upon solution temperature, dielectric constant, and ionic strength. It was accepted, consequently, that electrostatic factors along collagen and mucopolysaccharide macromolecules greatly influence the hydration and elasticity of tendons. Displacement of water by alcohols elevated the elastic modulus. However, the force required to produce a 1 % extension, a stress-strain relationship, did not change with aging. Thermoelastic measurements indicated that the glass and shrinkage transition temperatures also did not change with animal age. 3. From these observations of biophysical properties, it was concluded that flexebility of tendon is very sensitive to solution parameters. A glass-state of macromolecular structure also contributes to molecular cohesiveness of collagen and mucopolysaccharide. Production of joint-stiffness, therefore, could be influenced by these physical-chemical factors. However, deleterious effects produced in the articular cartilage, causing an elevation in surface friction, also was considered as a possible factor.
Elastic properties of rigid fiber-reinforced composites

We study the elastic properties of rigid fiber‐reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson’s ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital‐image‐based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.
Synthesis of Mitochondrial Proteins after Stimulation of Ovarian Follicles by Luteinizing Hormone

Treatment of isolated ovarian follicles with LH results in an increase in pregnenolone and progesterone secretion. Furthermore, LH treatment of follicles increases mitochondrial cholesterol conversion activity but does not significantly affect the mitochondrial ATP synthesis rate. Since these changes in pregnenolone synthesis may be due, at least in part, to changes in the components of mitochondria, we investigated the synthesis of mitochondrial proteins in response to treatment of follicles with LH. Follicles (4–6 mm in diameter) were isolated from porcine ovaries and incubated for 24 h without or with LH (1<μg/ml medium 199D), in the presence of [3H]leucine (without LH) or [14C]leucine (with LH). Untreated and LH-treated follicles were combined, and a mitochondrial sample was prepared. The mitochondrial proteins were separated by sodium dodecyl sulfate-gel electrophoresis using 8% and 15% polyacrylamide gels, and the 14C to 3H ratio of slices was determined. General incorporation of radiolabeled leucin...
Palaeomagnetism and the Globorotalia truncatulinoides Datum in the Tasman Sea and Southern Ocean: Reply

DR THEYER replies: Watkins, Kennett and Vella's critique1 requires further discussion on a baffling stratigraphic problem occurring in the far South-east Indian Ocean. In that area, Globorotalia truncatulinoides overlaps with distinctive late Miocene-Pliocene foraminifers and radiolarians in at least twelve widely separated piston cores2,3. To explain an overlap of such magnitude and stratigraphic consistency by invoking simple reworking seemed unreasonable to me and I therefore proposed a mid-Pliocene (Gauss) G. truncatulinoides datum plane for this area2. There are, of course, alternative interpretations. One can assume, for example, that the region is affected by an extensive Brunhes-Gauss disconformity (representing a removal of mostly Matuyama sediments) and that some mixing of Brunhes and Gauss sediments has occurred above and below the hiatus. This explanation is compatible with a Quaternary range of G. truncatulinoides, which now seems established (J. P. Kennett, personal communication) for at least parts of the present area and would agree with the early Pliocene evolutionary sequence of the radiolarian Lamprocyclas heteroporos4 which occurs in the Gilbert sections of cores E39-40, E39-48 and E39-56 (ref. 3). It would also be in keeping with the 230Th dates in E39-40 (ref. 3) and the internal consistency of all important radiolarian and foraminiferal ranges in the cores. Finally, it would agree with previous work in this area which describes an erosional disconformity of predominantly Gauss age3,5. This alternative explanation is now being tested with additional palaeomagnetic work, 230Th analyses and study of nannofossils. I recognize that my original interpretation, which at the time of its composition seemed adequately substantiated by my findings2,3, is only one of other possible explanations and may even be wrong. Watkins, Kennett and Vella1, however, do not really question my interpretation as such, but attempt to invalidate it by discrediting my palaeomagnetic measurements and faunal identifications.