cssi/SciSciGPT-SciSciNet huggingface dataset:
Advances in vertical-cavity and widely-tunable lasers using InP-based PIC technology

Summary form only given. This paper reviews some recent developments in two rather different laser examples based upon two somewhat different alloy systems lattice-matched to InP. The quaternary materials systems are chosen to provide more or less optimal device characteristics in both cases. The first example is a lattice-matched vertical-cavity surface-emitting laser (VCSEL) that can be created to operate at any wavelength within the entire 1300-1600 nm range. The second example actually includes two versions of a photonic integrated circuit technology to generate widely-tunable sampled-grating lasers integrated with amplifiers (SOAs) and modulators.
Indole alkaloids of Haplophyton crooksii

An investigation of the indole alkaloids of Haplophyton crooksii has resulted in the identification of two new alkaloids10-methoxy-N1-methylpericyclivine (1) and 16-decarbomethoxyvinervinine (2)and 13 known alkaloidscrooksiine, yohimbine, β-yohimbine, crooksidine, decarbomethoxytetrahydrosecodine, akuammicine, tubotaiwine, lanceomigine, lanceomigine N-oxide, haplophytine, cimicine, cimicidine, and akuammidinas major alkaloids of this shrub. All of the isolated alkaloids showed an inhibition of acetylcholinesterase activity in vitro.
Pituitary gigantism caused by growth hormone excess from infancy

A 2 1/4-year-old boy with pituitary gigantism had a large pituitary macroadenoma. Gross tumor removal has prevented further visual losses, but he has had persistent hypersecretion of growth hormone and prolactin. Treatment with somatostatin analog has decreased both hormone secretion and growth velocity.
Transposable elements as mutator genes in evolution

Strains of the bacterium Escherichia coli habouring genes that increase mutation rates are known to have an evolutionary advantage in chemostat competition over otherwise isogeneic strains with lower mutation rates1–3. This advantage is frequency-dependent, the mutator strain being favoured only above a starting ratio of ∼5×10−5, and it results from the fact that the necessary beneficial mutations cannot be generated in a mutator population below a certain size3. Here we consider the possibility that the mutagenic4,5 properties of transposable elements confer an advantage in the same manner as mutator genes. A previous report has shown that the transposon Tn5 increases the fitness of E. coli in chemostats, although the reason for this effect has not been established6. Our results show that the transposon Tn10 also confers an advantage in chemostats. In addition, we find that (1) this advantage, like that associated with mutator genes, is frequency-dependent, (2) whenever the Tn10 strains win, a segment of Tn10, probably its IS10 sequences, has undergone transposition to a new site, (3) the new insertions converge into a site contained within a 3.2 kilobase (kb) PvuII fragment of the genome, and (4) no transpositions are detected when the Tn10 population lses. We conclude that Tn10 confers an advantage by increasing the mutation rate of the host bacterium.
Temperature-Regulated Protein Synthesis by Leptospira interrogans

Leptospira interrogans is an important mammalian pathogen. Transmission from an environmental source requires adaptations to a range of new environmental conditions in the organs and tissues of the infected host. Since many pathogenic bacteria utilize temperature to discern their environment and regulate the synthesis of appropriate proteins, we investigated the effects of temperature on protein synthesis in L. interrogans. Bacteria were grown for several days after culture temperatures were shifted from 30 to 37°C. Triton X-114 cellular fractionation identified several proteins of the cytoplasm, periplasm, and outer membrane for which synthesis was dependent on the culture temperature. Synthesis of a cytoplasmic protein of 20 kDa was switched off at 37°C, whereas synthesis of a 66-kDa periplasmic protein was increased at the higher temperature. Increased synthesis of a 25-kDa outer membrane protein was observed when the organisms were shifted from 30 to 37°C. A 36-kDa protein synthesized at 30 but not at 37°C was identified as LipL36, an outer membrane lipoprotein. In contrast, expression of another lipoprotein, LipL41, was the same at either temperature. Immunoblotting with convalescent equine sera revealed that some proteins exhibiting thermoregulation of synthesis elicited antibody responses during infection. Our results show that sera from horses which aborted as a result of naturally acquired infection with L. interrogans serovar pomona type kennewicki recognize periplasmic and outer membrane proteins which are differentially synthesized in response to temperature and which therefore may be important in the host-pathogen interaction during infection.
Sharpening the generalized Noether bound in the invariant theory of finite groups

Abstract We consider linear representations of a finite group G on a finite dimensional vector space over a field F in which |G| is invertible. By a theorem due to E. Noether in char 0, and to Fleischmann and Fogarty in general, the ring of invariants is generated by homogeneous elements of degree at most |G|. Schmid, Domokos, and Hegedus sharpened Noether's bound when G is not cyclic and char F=0. We prove that the sharpened bound holds over general fields: If G is not cyclic and |G| is invertible in F, then the ring of invariants is generated by elements of degree at most 3 4 ·|G| if |G| is even, and at most 5 8 ·|G| if |G| is odd.
Molecular dissection of effector cell protease receptor-1 recognition of factor Xa. Assignment of critical residues involved in antibody reactivity and ligand binding.

Abstract Receptor-mediated assembly of blood proteases on vascular cells maintains the hemostatic balance and initiates intracellular signal transduction. Effector cell protease receptor-1 (EPR-1) is an ∼62-kDa vascular cell membrane receptor for the clotting protease factor Xa, participating in thrombin formation and lymphocyte activation. Here, recombinant EPR-1 fragments were engineered in the frame of intercellular adhesion molecule-1, transfected in mammalian cells, and analyzed for antibody recognition and ligand binding. Chimeric transfectants containing the EPR-1 sequence Met1-Arg60 bound the immunosuppressive anti-EPR-1 monoclonal antibody (mAb) 2E1. In contrast, transfected cells expressing the EPR-1 sequence Pro120-Ala154 were recognized by the functionally inhibitory anti-EPR-1 mAbs 9D4 and B6, bound 125I-factor Xa in a reaction quantitatively indistinguishable from that of wild-type EPR-1 transfectants, and promoted factor Xa concentration-dependent prothrombin activation in the absence of exogenous factor V/Va. Chimeric transfectants expressing the COOH terminus end of the EPR-1 extracellular domain (Ala157-Glu221) did not bind anti-EPR-1 mAbs and did not associate with factor Xa. Mutagenesis of Asn131 or Lys133 in the EPR-1 ligand recognition domain abolished factor Xa binding by 80 ± 5.5 and 96 ± 4%, respectively, while mutation of Lys126, Gly128, Asn129, and Asn134 was without effect. A synthetic peptide duplicating the EPR-1 sequence S123PGKPGNQNSKNEPP137 dose dependently inhibited factor V/Va-independent thrombin generation of resting endothelium (IC50 ∼ 1 μM), while the adjacent EPR-1 sequence P136PKKRERERSSHCYP150 was ineffective. These findings demonstrate that EPR-1 contains two spatially distinct functional domains implicated in lymphocyte activation (Met1-Arg60) or factor Xa binding and prothrombin activation (Pro120-Ala154). These interacting sequences may provide a novel potential target for inhibition of factor Xa-dependent vascular cell responses.
The human cytomegalovirus UL44 C clamp wraps around DNA.

Summary Processivity factors tether the catalytic subunits of DNA polymerases to DNA so that continuous synthesis of long DNA strands is possible. The human cytomegalovirus DNA polymerase subunit UL44 forms a C clamp-shaped dimer intermediate in structure between monomeric herpes simplex virus UL42, which binds DNA directly via a basic surface, and the trimeric sliding clamp PCNA, which encircles DNA. To investigate how UL44 interacts with DNA, calculations were performed in which a 12 bp DNA oligonucleotide was docked to UL44. The calculations suggested that UL44 encircles DNA, which interacts with basic residues both within the cavity of the C clamp and in flexible loops of UL44 that complete the "circle." The results of mutational and crosslinking studies were consistent with this model. Thus, UL44 is a "hybrid" of UL42 and PCNA: its structure is intermediate between the two and its mode of interaction with DNA has elements of both.
Neonatal outcomes of fetuses diagnosed with life-limiting conditions when individualized comfort measures are proposed.

Neonatal outcomes of fetuses diagnosed with life-limiting conditions when individualized comfort measures are proposed
A Window on the Valencia of Jaume the Conqueror: A five-Year Core Sample, 1264-1270

During the years 1265 to 1270 King Jaume I culminated his career as warrior and hero of Christendom, amid diplomatic triumphs, commercial expansion, and military glory, ending however in personal humiliation and the collapse of his plans for a Jerusalem crusade. The kingdom of Valencia, then in a period of intense post-conquest consolidation, was central to his activities. This article surveys the 500 documents in the king's registers about Valencia for that short period, organizing them around the themes of Physical Space, the Human Geography both political and economic, the Fiscal Space, the Juridical Space, the Sacret Space, the "Parallel Societies" of Jews and Mudejars, the world of women, and the Murcian Crusade in Valencian Perspective. Each of the hundreds of elements comprising this five-year panorama is accompanied by the number of a document or documents from the forthcoming third volume of the Diplomatarium of King Jaume. The structure and dynamics of his new kingdom are revealed in this abundance of anecdotes, personal glimpses and self-enclosed narratives of those remarkable documents and their obiter dicta.
Learning Physics with Digital Game Simulations in Middle School Science

The purpose of this work is to share our findings in using video gaming technology to facilitate the understanding of basic electromagnetism with middle school students. To this end, we explored the impact of using a game called Supercharged! on middle school students’ understanding of electromagnetic concepts compared to students who conducted a more traditional inquiry-oriented investigation of the same concepts. This study was a part of a larger design experiment examining the pedagogical potential of Supercharged! The control group learned through a series of guided inquiry methods while the experimental group played Supercharged! during the laboratory sections of the science course. There was significant difference, F(2,91) = 3.6, p < 0.05, η 2 = 0.77, between the control and experimental groups on the gains from pre- to post-assessment. Additionally, students in the experimental group were able to give more nuanced responses about the descriptions of electric fields and the influence of distance on the forces that charges experience due to their interactions with the Supercharged! game. Results of this study show that video games can lead to positive learning outcomes, as demonstrated by the increase in test scores from pre- to post-assessment and the student interviews. This study also suggests that a complementary approach, in which video games and hands-on activities are integrated, with each activity informing the other, could be a very powerful technique for supporting student scientific understanding. Further, our findings suggest that game designers should embed meta-cognitive activities such as reflective opportunities into educational video games in order to provide scaffolds for students and to reinforce that they are engaged in an educational learning experience.
Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations

[1] Undulations on the equatorward edge of the diffuse proton aurora have been identified by using TIMED/GUVI auroral images in the far ultraviolet wavelengths. While undulations have been previously reported on the duskside (Lui et al., 1982), GUVI observations show the undulation also occurs in the dayside, nightside, and morningside. The GUVI proton auroral images provide direct optical evidence that the undulations occur in the proton aurora. It is also the first detection of the undulation in the dayside indicating strong convection shear in the region. The undulation in the nightside, a wavy structure in the whole diffuse proton aurora, is significantly different from those in the duskside and dayside. While almost all of the undulation events are observed during magnetic storms (Dst 1000 m/s) and strong velocity shear (>0.1 s−1) within the diffuse aurora oval are necessary conditions for the undulation to occur. The SSIES data also indicate the areas with large ion drift velocity and shear move to higher latitudes in the MLT sectors toward midnight. This may explain why the undulation is rarely detected in the nightside.
Indications of pre- and post-synaptic 5-HT1A receptor interactions in feeding behavior and neuroendocrine regulation

This bipartite study uses behavioral and biochemical means to explore the involvement of both pre- and post-synaptic 5-HT1A receptors in the control of food intake and neuroendocrine regulation. In the pharmacological study, the administration of the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 60 μg/kg b.wt., i.p.) to rats caused a significant increase in 2 h intake of a high carbohydrate (CARB)/sugar diet (P < 0.05) during the relatively inactive feeding period of the late light cycle. No significant change was detected in the intake of Purina laboratory chow at 2 h, or of the intake of either diet at 4 h and 24 h after 8-OH-DPAT administration. Injection of 8-OH-DPAT induced a drop in insulin levels in rats maintained on high CARB/sugar diets only (−90%; P<0.05). It also caused an increase in circulating glucose levels in both high CARB/sugar (240%; P<0.01) and chow fed (123%; P<0.05) rats; it did so more intensely in high CARB/sugar-fed rats. In the biochemical study, radioligand binding techniques were used to assess 5-HT1A receptor density in the hypothalamus, as well as the relationship between 5-HT1A receptors and circulating levels of insulin and glucose. Chronic and acute administration (25 mg/kg b.wt./5 injections, and 50 mg/kg b.wt., respectively, i.p.) of the potent hypoglyce mic agent tolbutamide (TOL) caused a significant increase in 5-HT1A receptor density (+243% and +132.6%, respectively; P<0.05) in the medial hypothalamus but not in the lateral hypothalamus, as compared to vehicle-treated rats. Chronic glucose replacement therapy showed a trend towards reversing the depressed circulating glucose levels as well as the medial hypothalamic 5-HT1A receptor density to control levels. These studies indicate that the pre-synaptic mechanism of 8-OH-DPAT-induced hyperphagia may require specific circulating levels of insulin and glucose, which are regulated via post-synaptic 5-HT1A receptors.
Calculation of radiative properties of nonequilibrium hydrogen plasma

A computer program called NEQRAP is described that calculates the radiative properties of nonequilibrium ionized hydrogen. From the given electron temperature, electron density, and atom density values (which do not necessarily satisfy the equilibrium relationship) and intensities of incident radiation, the non-Boltzmann populations of electronic states are computed by solving the equation of quasi-steady-state population distribution. Emission and absorption coefficients are determined as functions of wavelength by invoking the principle of detailed balance between the upper and lower states of each radiative transition. Radiative transport through the medium is computed assuming a one-dimensional uniform slab. The rate of ionic reaction is also computed. When used on a sample case, the program shows that there is a large difference between the calculated intensities of radiation emitted by a bulk of equilibrium and nonequilibrium hydrogen. The accuracy of the program is estimated to be better than 10%.
Hair cell counts in an age-graded series of rat cochleas

Hair cells of Sprague-Dawley rats aged 2-33 months were counted in order to assess the magnitude, location and time course of cell degeneration. The mean number of hair cell places (hair cells plus phalangeal scars) was approximately 4700: 960 inner hair cell places and 3470 outer hair cell places. These numbers do not vary systematically with age. Hair cell degeneration was observed in all animals. At 31-33 months of age, animals had inner hair cell losses ranging from 1.6 to 4.2% and outer hair cell losses ranging from 2.1 to 23.3%. The loss of hair cells was greatest in the upper apex, where the 31-33-month-old animals had 3.1-9.2% inner hair cell losses and 7.4-46.8% outer hair cell losses. Outer hair cell losses were also large in the basal end, where inner hair cell losses were small. In the older animals, hair cell losses were consistently most prominent in the third row of outer hair cells. Following examination of the hair cell population, the ganglion cells in the apical region were evaluated in a number of cochleas. No significant correlation was found between the magnitude of inner hair cell and ganglion cell losses.
Host ranges, symptoms and amino acid compositions of eight potexviruses

SUMMARY The host ranges, symptom expression and coat protein compositions of eight definitive potexviruses are described and compared. Only limited host range similarity was observed: clover yellow mosaic virus and white clover mosaic virus shared 11 of the 28 host species tested; foxtail mosaic virus and narcissus mosaic virus infected monocotyledons; barrel cactus virus and viola mottle virus had narrow host ranges but had eight of the host species in common. Amino acid analyses of coat proteins showed some similarity among the viruses tested, but little correlation with the different host range types. There was more variation of structurally important amino acids such as lysine, arginine, leucine and proline than might have been expected, but high alanine and low tyrosine, tryptophan, cysteine and methionine were typical of plant virus coat proteins.
Carbon isotopic fractionation by the marine diatom Phaeodactylum tricornutum under nutrient- and light-limited growth conditions

Abstract A theoretical model was developed to explain the characteristics of carbon isotopic fractionation (eP) by the marine diatom Phaeodactylum tricornutum under nutrient- and light-limited growth conditions. The model takes into consideration active transport and diffusion of inorganic carbon through the cell membrane and chloroplast membrane and the energetic tradeoff between production of Rubisco and operation of a carbon-concentrating mechanism to achieve a given growth rate. The model is able to explain 88% of the variance in experimental ep data reported in this study and in previous work and is able to account for the observed pattern of Rubisco activity in nitrate-limited chemostats. Two important implications of the model include the fact that ep is not a unique function of the ratio of growth rate to external CO2 concentration (as opposed to the predictions of several previous models) and that changes in light-limited and nutrient-limited growth rates have opposite effects on the fraction of CO2 taken up by the chloroplast that is lost to diffusion and hence on certain patterns of carbon isotopic fractionation.
Arbitrary Waveform Generator Response Shaping Method to Enable ADC Linearity Testing on Very Low Cost Automatic Test Equipment

Mixed signal parametric testing is resource intensive and requires high-precision source and capture instrumentation to screen parametric faults. Analog to digital converters (ADC) require analog sources to provide stimulus while digital instrumentation with digital signal processing (DSP) support is used for output analysis. Precision requirements for test instrumentation are driven by the circuit under test (CUT) specifications and required to ensure minimal test escapes or excessive fallout due to source generated artifacts. Stringent accuracy requirements for the arbitrary waveform generator (AWG) modules on Ate are responsible to high hardware costs. We propose a linearity correction methodology to compensate for linearity distortion present in the analog source generator to eliminate the resulting artifacts that can cause false failures or passes. This method can be used to reduce the linearity requirement criteria for AWGs that are present in the Very-Low-Cost ATE (VLC-ATE) systems.
Experiments on the instabilities of a swirling jet

Instabilities present in a swirling jet in the Reynolds number range from 20 000 to 60 000 and a nominal swirl number of 0.5 were studied experimentally, using smoke visualization, hot‐wire anemometry and acoustic excitation. Flow visualization photographs of the natural jet show vortex breakdown at the core and rolling up of the shear layer around the jet into weak, irregular, large‐scale organized structures. When forced by acoustic excitation these structures became energetic and periodic. Axisymmetric and helical instability waves in the Strouhal number range 0.75 to 1.5 were excited and their evolution along the axial direction were measured from velocity spectra and ensemble averaged measurements. Compared to a nonswirling jet, the overall growth of the instability waves is considerably smaller, and vortex pairing is suppressed in a swirling jet. However, the overall spread and mass entrainment rates are higher in the latter. Measurements of the mean velocity components and turbulence fluctuations show that the vortex breakdown affects the axial velocity distribution and rapidly replaces the potential core with a large amount of turbulence. Upon interacting with the vortex breakdown, the shear layer along the jet periphery loses its organized structure and, in general, ‘‘random turbulence’’ follows.
Catheter-based interventions guided solely by a new phased-array intracardiac imaging catheter: in vivo experimental studies.

Abstract Background: Intracardiac echocardiography (ICE) has had useful but limited use during interventional procedures because of technologic limitations. We used a novel phased-array ICE device (AcuNav) with 2-dimensional sector imaging and full Doppler capability to see whether it could guide cardiac interventions without fluoroscopy. Methods: Twelve dogs were studied, and we performed atrial septostomy, tricuspid, and pulmonary valve disruption using only ICE. Preinterventional and postinterventional anatomic and hemodynamic data were noted. Results: All attempts were successful in the placement of the ICE catheter (100%). We attempted septostomy on 11 dogs and were successful 8 times (73%). Tricuspid valve disruption and balloon dilatation were performed successfully on 5 dogs (100%). We attempted pulmonary valve disruption on 4 dogs and could always correctly place the guidewire (100%). We performed pulmonary valve balloon dilatation on one dog (25%). A comprehensive echocardiographic examination was always possible. Conclusion: This new ICE device can guide interventions without fluoroscopy. However, further studies are needed to evaluate whether it can replace fluoroscopy. (J Am Soc Echocardiogr 2002;15:150-8.)
The development of children ages 6 to 14.

The years between 6 and 14—middle childhood and early adolescence—are a time of important developmental advances that establish children’s sense of identity. During these years, children make strides toward adulthood by becoming competent, independent, self-aware, and involved in the world beyond their families. Biological and cognitive changes transform children’s bodies and minds. Social relationships and roles change dramatically as children enter school, join programs, and become involved with peers and adults outside their families. During middle childhood, children develop a sense of self-esteem and individuality, comparing themselves with their peers. They come to expect they will succeed or fail at different tasks. They may develop an orientation toward achievement that will color their response to school and other challenges for many years. In early adolescence, the tumultuous physical and social changes that accompany puberty, the desire for autonomy and distance from the family, and the transition from elementary school to middle school or junior high can all cause problems for young people. When adolescents are in settings (in school, at home, or in community programs) that are not attuned to their needs and emerging independence, they can lose confidence in themselves and slip into negative behavior patterns such as truancy and school dropout. This article examines the developmental changes that characterize the years from 6 to 14, and it highlights ways in which the organization of programs, schools, and family life can better support positive outcomes for youths.
Loss of foundation species increases population growth of exotic forbs in sagebrush steppe

The invasion and spread of exotic plants following land disturbance threatens semiarid ecosystems. In sagebrush steppe, soil water is scarce and is partitioned between deep- rooted perennial shrubs and shallower-rooted native forbs and grasses. Disturbances commonly remove shrubs, leaving grass-dominated communities, and may allow for the exploitation of water resources by the many species of invasive, tap-rooted forbs that are increasingly successful in this habitat. We hypothesized that exotic forb populations would benefit from increased soil water made available by removal of sagebrush, a foundation species capable of deep-rooting, in semiarid shrub-steppe ecosystems. To test this hypothesis, we used periodic matrix models to examine effects of experimental manipulations of soil water on population growth of two exotic forb species, Tragopogon dubius and Lactuca serriola ,i n sagebrush steppe of southern Idaho, USA. We used elasticity analyses to examine which stages in the life cycle of T. dubius and L. serriola had the largest relative influence on population growth. We studied the demography of T. dubius and L. serriola in three treatments: (1) control, in which vegetation was not disturbed, (2) shrubs removed, or (3) shrubs removed but winter-spring recharge of deep-soil water blocked by rainout shelters. The short-term population growth rate (k )o fT. dubius in the shrub-removal treatment was more than double that of T. dubius in either sheltered or control treatments, both of which had limited soil water. All L. serriola individuals that emerged in undisturbed sagebrush plots died, whereas k of L. serriola was high (k . 2.5) in all shrub-removal plots, whether they had rainout shelters or not. Population growth of both forbs in all treatments was most responsive to flowering and seed production, which are life stages that should be particularly reliant on deep-soil water, as well as seedling establishment, which is important to most plant populations, especially during invasion. These data indicate the importance of native species, in this case the dominant shrub, in influencing soil resources and restricting population growth of exotic plants. These results argue that management of invasive plants should focus not only on removal of nonnatives, but also on reestablishment of important native species.
Is there a turning point in the relationship between income and energy use and/or carbon emissions?

Abstract We analyze the effect of fuel mix, model specification, and the level of development on the presence and size of a turning point in the relationship between income and energy use and/or carbon emissions. The results indicate that fuel mix, the specification for income, and the level of economic development affect conclusions about whether there is a turning point in the relationship between economic activity and energy use and carbon emissions. Including fuel shares generally reduces the size of a turning point that is estimated from a panel that includes observations from both OECD and Non-OECD nations. But this result varies according to the level of development. For OECD nations, there is limited support for a turning point in the relationship between income and per capita energy use and/or carbon emissions. For non-OECD nations, there is no turning point in the relationship between income and either energy use or carbon emissions. Instead, the relationship is positive. Together, the results indicate that forecasters and policy makers should not depend on a turning point in the relationship between income and energy use or carbon emissions to reduce either.
Coccoliths as Late Quaternary Palaeoclimatic Indicators in the Subantarctic Pacific Ocean

CLIMATIC fluctuations during the Pleistocene have been revealed by isotope and palaeontological studies of deep-sea cores from the Atlantic and Indian Oceans1–4 and the Pacific Ocean4–6. This article indicates the utility of two species of Coccolithophoridae as palaeoclimatic guides in high latitude areas. The eight deep-sea carbonate cores studied were collected from the National Science Research Vessel Eltanin in the South Pacific Ocean (Table 1).
Antimicrobial Therapy of Septicemia Due to Klebsiella pneumoniae in Neutropenic Rats

Three different isolates of Klebsiella pneumoniae, highly sensitive to amikacin but varying in susceptibility to cefazolin, were injected intraperitoneally into neutropenic rats. Animals were treated every 8 hr for 72 hr with saline (controls), cefazolin (full dose, 40 mg/kg; one-fourth dose, 10 mg/kg), amikacin (full dose, 8 mg/kg; onefourth dose, 2 mg/kg), or a combination of both drugs at either full dose or onefourth dose. All drugs were given intramuscularly. Combination therapy with full doses produced higher mean bactericidal titers in serum and more rapid clearance of bacteria from blood and peritoneal washings. However, cumulative mortality at 72 hr in rats treated with amikacin plus cefazolin in full doses (24%, 23%, and 44%) was not significantly different from mortality in rats treated with amikacin alone (34%, 17%, and 62%). Results with cefazolin alone were not significantly different from the mortality in control animals for two of the three challenge organisms. When the minimal inhibitory concentration of cefazolin was - 8 Ag/ml, in vivo synergy was suggested by the similar survival rate obtained with a combination of a one-fourth dose of each agent and with amikacin alone in a full dose. These results demonstrate the relative ineffectiveness of cefazolin for therapy of klebsiella septicemia and suggest that in vivo antimicrobial synergy occurs in combination therapy against strains of bacteria relatively sensitive to cephalosporins.
Absorption of solar radiation by the clear and cloudy atmosphere during the Atmospheric Radiation Measurement Enhanced Shortwave Experiments (ARESE) I and II: Observations and models

[1] As a follow-on to the Atmospheric Radiation Measurement (ARM) Enhanced Shortwave Experiment (ARESE) I, which provided atmospheric shortwave measurements from collocated aircraft, ARESE II performed similar measurements with a single aircraft flying at an altitude of 7 km over an instrumented surface site. ARESE I and ARESE II absorptance measurements are found to agree with each other and, when converted to top of the atmosphere (TOA) instantaneous column absorption, are also consistent with GOES 8 and Scanner for Radiation Budget (ScaRaB) satellite observations. Measurements are compared to calculations performed with five different radiative transfer models. It is found that the calculated absorption differs systematically from the observations in cloudy conditions, with models underpredicting the absorption. In particular, all the models tested here underpredict the measured instantaneous cloudy column absorption by amounts ranging from 17 to 61 W m−2, depending on the models and cases studied. The various models, using identical input, differ among themselves; for example, for the same cloudy case, absorptance estimates range from 0.22 to 0.27 for the atmospheric column from the surface to the TOA. It is also found that model-calculated absorptances appear not as well correlated to cloud optical depth variations as the measured absorptances appear to be. Measured and calculated clear-sky absorptances agree well within the uncertainties. Cloudy-sky absorptances in the visible spectral region (300 to 700 nm) reach values of as much as 0.02 during ARESE II while the equivalent measurements for ARESE I range around 0.06. This visible absorptance may be related to aerosols and their day-to-day and seasonal variability.
Specific detection of rhizobia in root nodules and soil using the polymerase chain reaction

Abstract The polymerase chain reaction (PCR) amplification of specific DNA sequences, allows specific and sensitive detection of bacteria at the genus, species or strain level depending on the design of the oligonucleotide primers. In this study we utilized 20 mer primers that flanked a 300 bp region of the npt II gene of the transposon Tn5 thus allowing for the amplification of this region. Insertion of the Tn 5 element into rhizobia allowed for detection of these cells using PCR amplification. Using the npt II -specific primers and Tn5 insertion mutants of Rhizobium leguminosarum bv. phaseoli we were able to detect these specific rhizobia strains in root nodules of bean plants and in inoculated soils. Utilization of genus-specific gene sequences would allow for estimates of cells of that genus in environmental samples. Conversely, use of gene sequences common to rhizobia, e.g. nif and nod sequences, would give estimates of the population of rhizobia. This paper serves to illustrate the use of PCR, for detecting gene sequences in an environmental sample such as a root nodule.
A proposed college curriculum in simulation

The status of simulation education at Clemson University is investigated with respect to the current requirements of industry use of simulation as an analytical tool. A sequence of courses addressing all phases of the simulation analysis and modeling procedure is described. A taxonomy of simulation topics by area and curriculum level is provided. A survey of industry simulation analysts is utilized to assist in specifying the proposed educational requirements to ensure that Clemson industrial engineers are provided with adequate training.
Paired tone facilitation in dorsal cochlear nucleus neurons: A short-term potentiation model testable in vivo

It has been suggested that the dorsal cochlear nucleus (DCN) is involved in coding stimulus history or prior auditory activity [Manis (1989) J. Neurophys., 61, 149-161; Manis (1990) J. Neurosci., 10, 2338-2351]. The major output neurons of the DCN are the fusiform (pyramidal) cells which are thought to receive excitatory inputs from the descending branch of the acoustic nerve onto their basal dendrites and significant inhibitory glycinergic and GABAergic inputs to the soma and dendrites. The apical dendrites of these neurons lie within the molecular layer of the DCN and encounter parallel fibers which are thought to utilize the excitatory amino acid neurotransmitter glutamate. In this study of anesthetized chinchillas, we found that, in contrast to the responses of acoustic nerve fibers and most cochlear nucleus neurons which are masked by an appropriate preceding signal, many DCN principal cells are facilitated during the second of two identical stimuli. Facilitated DCN responses often have a reduced interspike interval and a more chopper-like temporal response pattern to the second characteristic frequency tone. This paired tone facilitation in the chinchilla DCN provides as in vivo model of short-term potentiation elicited by sensory stimulation similar to the paired-pulse facilitation observed with electrical stimulation in other models.
Highly persistent polycyclic aromatic hydrocarbon-DNA adducts in mouse skin: detection by 32P-postlabeling analysis.

Abstract A 32 P-postlabeling method for carcinogen-DNA adduct analysis recently developed in our laboratory was applied to skin DNA from mice treated topically with polycyclic aromatic hydrocarbons (PAHs). After application of 4 doses of 1.2 μmol each of benzo[ a ]pyrene (BP), 3-methylcholanthrene (MC) and 7,12-dimethylbenz[ a ]anthracene (DMBA), respectively, total covalent adduct binding in mouse skin DNA initially amounted to 1 adduct in 6.0 × 10 4 –1.3 × 10 5 nucleotides. Four weeks after treatment, these levels had declined to 1 adduct in 1.4 × 10 6 –2.7 × 10 6 nucleotides. Substantial removal of DNA adducts occurred during the first 2 weeks after carcinogen application while adducts remaining thereafter underwent little or no repair between 2 and 4 weeks after treatment. These results raise the possibility that the persistent adducts occupy specific genomic sites in quiescent cells where they may not be amenable to repair because of localized conformational alterations of DNA or shielding by associated proteins.
Constraints on superconducting transition temperatures in the cuprates : antiferromagnetic spin fluctuations

Recently, several authors have suggested that antiferromagnetic spin fluctuations provide the pairing mechanism in the high-temperature superconductors. In this paper, we discuss this spin-fluctuation mechanism in the Fermi-surface-restricted Eliashberg formalism using a dynamical susceptibility whose form is constrained by neutron-scattering data. For definiteness, we consider the ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ family of superconductors, which we model with a realistic model band structure. Furthermore, we choose the electron-spin fluctuation coupling constant \ensuremath{\lambda} to yield agreement with low-frequency ac conductivity measurements. We find that spin-singlet pairing can occur only for ${\mathit{B}}_{1}$ and ${\mathit{A}}_{2}$ symmetries and that the former symmetry yields the higher critical temperature ${\mathit{T}}_{\mathit{c}}$. The ${\mathit{T}}_{\mathit{c}}$ associated with the ${\mathit{B}}_{1}$ symmetry is large in the weak-coupling limit, but is greatly reduced when strong-coupling effects are included. Finally, we observe that even for anisotropic pairing schemes, transport data that constrain \ensuremath{\lambda} provide stringent limits on the critical temperature.
Unified theory of symmetry for two-dimensional complex polynomials using delta discrete-time operator

The complexity in the design and implementation of 2-D filters can be reduced considerably if the symmetries that might be present in the frequency responses of these filters are utilized. As the delta operator (?-domain) formulation of digital filters offers better numerical accuracy and lower coefficient sensitivity in narrow-band filter designs when compared to the traditional shift-operator formulation, it is desirable to have efficient design and implementation techniques in ?-domain which utilize the various symmetries in the filter specifications. Furthermore, with the delta operator formulation, the discrete-time systems and results converge to their continuous-time counterparts as the sampling periods tend to zero. So a unifying theory can be established for both discrete- and continuous-time systems using the delta operator approach. With these motivations, we comprehensively establish the unifying symmetry theory for delta-operator formulated discrete-time complex-coefficient 2-D polynomials and functions, arising out of the many types of symmetries in their magnitude responses. The derived symmetry results merge with the s-domain results when the sampling periods tend to zero, and are more general than the real-coefficient results presented earlier. An example is provided to illustrate the use of the symmetry constraints in the design of a 2-D IIR filter with complex coefficients. For the narrow-band filter in the example, it can be seen that the ?-domain transfer function possesses better sensitivity to coefficient rounding than the z-domain counterpart.
Human circadian system causes a morning peak in prothrombotic plasminogen activator inhibitor-1 (PAI-1) independent of the sleep/wake cycle

Serious adverse cardiovascular events peak in the morning, possibly related to increased thrombosis in critical vessels. Plasminogen activator inhibitor-1 (PAI-1), which inhibits fibrinolysis, is a key circulating prothrombotic factor that rises in the morning in humans. We tested whether this morning peak in PAI-1 is caused by the internal circadian system or by behaviors that typically occur in the morning, such as altered posture and physical activity. Twelve healthy adults underwent a 2-week protocol that enabled the distinction of endogenous circadian effects from behavioral and environmental effects. The results demonstrated a robust circadian rhythm in circulating PAI-1 with a peak corresponding to ∼6:30 am. This rhythm in PAI-1 was 8-times larger than changes in PAI-1 induced by standardized behavioral stressors, including head-up tilt and 15-minute cycle exercise. If this large endogenous morning peak in PAI-1 persists in vulnerable individuals, it could help explain the morning peak in adverse cardiovascular events.
Stability of two-phase flow calculation using two-fluid models

Abstract Two-fluid modeling of two-phase flow may yield a system of partial differential equations having complex characteristics; this results in a mathematically ill-posed initial-value problem. Despite the fact that no finite-difference method for solving such a problem can be stable in the usual sense, finite-difference solution of two-fluid models is in widespread use. We investigate the numerical behavior of one such set of difference equations, derive conditions under which solutions appear to be well behaved, and offer a physical interpretation.
Romano Ward Syndrome in Pregnancy

Romano-Ward syndrome is an unusual and potentially devastating disorder manifested by prolongation of the QT interval. Persons with this syndrome are at risk for sudden death from ventricular dysrhythmis. A case of a gravid woman with the disorder is presented
The Concentration of Cellular Nitrogenase Proteins inAzotobacter vinelandiiWhole Cells as Determined by Activity Measurements and Electron Paramagnetic Resonance Spectroscopy

Abstract The concentration of MoFe protein (Av1) inAzotobacter vinelandiiwhole-cell crude extract was measured by electron paramagnetic resonance spectroscopy at g = 3.7 resonance. The Av1 concentration was also measured from the activity of crude extract to which increasing amounts of purified Av1 and Av2 were added. The Av2 concentration was determined by fitting activity measurements of crude extract and crude extract to which purified Av2 was added. The Av1 concentration was found to be 26–28 μ M and that for Av2 was 42–45 μ M in whole cells, with a Av2/Av1 ratio of 1.6.In vitroactivity measurements carried out as a function of Av1 concentration at Av2/Av1 ratios of 1 and 4 showed a dilution effect below 0.08 μ M , a factor of 2 below that observed for nitrogenase reactivity forKlebsiella pneumoniae.No deviations from linearity were observed up to 26 μ M for the Av1–Av2 interaction. The flavoprotein (AvFlp) was shown to enhance nitrogenase reactivity at low Av2/Av1 ratios, a result attributed to decreasing theKmfor Av2–Av1 interaction. Direct reduction of bound Av2 is possibly the source of this kinetic enhancement. The kinetic results are considered in terms of the Thorneley and Lowe scheme.
A requirements sublanguage for automated analysis

The development of a restricted natural language for expressing requirements is described. the purpose of the language is to support readable specifications, which can be analyzed for errors and automatically interpreted. the specific language designed here is for specification of digital systems. Semantics are represented in a type of semantic network constructed of concepts and relations. the semantic basis, consisting of concept and relation types together with semantic patterns, is developed from an examination of several formal specification and design notations, together with a selection of natural language statements from product descriptions. the syntax of the language is developed from a syntactic analysis of natural language statements, and the productions of the grammar are selected to maximize coverage of syntactic structures used in the selection. © 1995 John Wiley & Sons, Inc.
Theory of spinor Fermi and Bose gases in tight atom waveguides

Divergence-free pseudo-potentials for spatially even- and odd-wave interactions in spinor Fermi gases in tight atom waveguides are derived. The Fermi-Bose mapping method is used to relate the effectively one-dimensional fermionic many-body problem to that of a spinor Bose gas. Depending on the relative magnitudes of the even- and odd-wave interactions, the $N$-atom ground state may have total spin $S=0$, $S=N∕2$, and possibly also intermediate values, the case $S=N∕2$ applying near a $p$-wave Feshbach resonance, where the $N$-fermion ground state is space-antisymmetric and spin-symmetric. In this case the fermionic ground state maps to the spinless bosonic Lieb-Liniger gas. An external magnetic field with a longitudinal gradient causes a Stern-Gerlach spatial separation of the corresponding trapped Fermi gas with respect to various values of ${S}_{z}$.
A microsphere-surface impact model for implementation in computational fluid dynamics

Abstract Two microsphere-surface impact models have been developed for implementation with computational fluid dynamic software. The models consider either normal or oblique incidence of a microsphere with the surface. The first model includes the effects of microsphere-surface roughness, and Hertzian and adhesion damping during surface contact. The second model considers the impact of elastic–plastic sphere and a surface, with and without interface adhesion. Analytical solutions for the coefficients of restitution are presented in terms of the impact velocity and material properties. These algebraic models were validated by comparison with the experimental results of several investigators. A user-defined function representing the model was developed to interface with the commercial software package FLUENT ® . The combined modelling package's predictions were compared with high-speed digital images of microparticle contact with the surface located on the floor of a wind tunnel.
The effect of rhombencephalic hypoplasia on posterior cranial base elongation in rodents.

Abstract A single intraperitoneal injection of methylazoxymethanol acetate in circumnatal rats produces a dose dependent cerebellar hypoplasia. All other tissues, including skeletal, are unaffected. Consequent decrease, in the ventral length attained by the growing rhombencephalon is accompanied by a corresponding decrease in the length of the basioccipital bone relative to that of the normally dimensioned basisphenoid bone. The width of the sphenooccipital synchondrosis is also proportionally decreased, with characteristic alterations in the structure of the several zones of this synchondrosis as compared to controls. Three autosomal recessive mutant mice strains were also studied in which the defect is manifested solely as decreased cerebellar neuronal neogenesis. Again, proportional linear decreases occurred in the ventral length of the rhombencephalon, the basioccipital bone and in width of spheno-occipital synchondrosis. The histological changes observed between normal and mutant mice were related to these differences. These data suggest that posterior cranial base elongation and the processes of endochondral ossification in the spheno-occipital synchondrosis of rodents are significantly regulated by the demands of functionally related growing neural masses.