cssi/SciSciGPT-SciSciNet huggingface dataset:
Lack of benefit of an active pectoral pulse generator on atrial defibrillation thresholds.

Effect of an Active Can on Atrial DFTs.Introduction: Atrial defibrillation can be achieved with standard implantable cardioverter defibrillator leads, which has led to the development of combined atrial and ventricular devices. For ventricular defibrillation, use of an active pectoral electrode (active can) in the shocking pathway markedly reduces defibrillation thresholds (DFTs). However, the effect of an active pectoral can on atrial defibrillation is unknown. Methods and Results: This study was a prospective, randomized, paired comparison of two shock configurations on atrial DFTs in 33 patients. The lead system evaluated was a dual-coil transvenous defibrillation lead with a left pectoral pulse generator emulator. Shocks were delivered either between the right ventricular coil and proximal atrial coil (lead) or between the right ventricular coil and an active can in common with the atrial coil (active can). Delivered energy at DFT was 4.2 ± 4.1 J in the lead configuration and 5.0 ± 3.7 J in the active can configuration (P = NS). Peak current was 32% higher with an active can (P < 0.01), whereas shock impedance was 18% lower (P < 0.001). Moreover, a low threshold (< 3 J) was observed in 61% of subjects in the lead configuration but in only 36% in the active can configuration (P < 0.05). There were no clinical predictors of the atrial DFT. Conclusion: These results indicate that low atrial DFTs can be achieved using a transvenous ventricular defibrillation lead. Because no benefit was observed with the use of an active pectoral electrode for atrial defibrillation, programmable shock vectors may be useful for dual-chamber implantable cardioverter defibrillators.
On the existence of an extraterrestrial source of water vapor in the middle atmosphere

Observations of the ultraviolet dayglow of atomic oxygen from the DE-1 spacecraft (Frank et al., 1986a,b) have revealed the existence of frequent localized decreases ("holes") in the emitted intensity. These have been interpreted as evidence of a steady influx of small "comets" whose icy envelope would provide a source of H2O molecules in the upper thermosphere. Using a one-dimensional model of middle-atmosphere composition, we show that the mesospheric water-vapor concentration implied by this influx is much larger than the range of observed values. We suggest that the entry of such an icy object into the atmosphere at meteoric speeds is likely to lead to dissociation of H2O molecules, and to a primary downward flux of OH rather than H2O. This would reduce significantly the predicted increase in H2O concentrations in the mesosphere, and would introduce a different mechanism for the production of the airglow holes, i.e., chemical destruction of atomic oxygen by the fast reaction with OH. The constraints imposed on this scenario by the mesospheric water-vapor measurements are examined, and we conclude that the permissible flux is some 30 times smaller than that proposed by Frank et al. The individual airglow holes would then have diameters of order 10 km instead of 50 km, and would be much less intense as seen by the DE-1 instrument than those reported. We conclude that the mechanism, though relaxing the constraints on extraterrestrial water fluxes considerably, falls well short of explaining the observations.
Rotation of mercury: theoretical analysis of the dynamics of a rigid ellipsoidal planet.

The second-order nonlinear differential equation for the rotation of Mercury is shown to imply locked-in motion when the period is within the range (2T/3) [1-{lambda} cos 2{pi}t/T {+-} 2/3 (21{lambda}e/2){sup 1/2}], where e is the eccentricity and T the period of Mercury's orbit, the time t is measured from perihelion, and {lambda} = (B-A)/C measures the planet's distortion. For values near 2T/3, the instantaneous period oscillates about 2T/3 with period (21{lambda}e/2){sup -1/2}T.
Null controllability of systems with control constraints and state saturation

Abstract Sufficient conditions for the null controllability of discrete-time systems with control constraints and state saturation are presented. This is accomplished in two stages: First, we establish a result for the asymptotic stability of such systems under zero input conditions. Next, we utilize this stability result to obtain a condition for the null controllability of such systems. We include specific examples to demonstrate the applicability of the present results.
On the role of mean meridional motions in the biennial wind oscillation

Detailed time-height sections and meridional cross-sections of zonal wind are presented for the zonally averaged conditions between 32°N and 20°S. The patterns which appear in the sections vary slowly and systematically with latitude and time. The biennial wind oscillation is evident in the sections, but since 1963, the two year periodicity, as such, has vanished and the wind fluctuations, though still similar in form to the previous ones, have become much less predictable. The sections suggest that the lower edges of westerly regimes propagate downwards more rapidly than those of easterly regimes. The momentum budget of the region is then examined, term by term, and it is concluded that a mean downward motion is necessary over the Equator to account for the downward propagation of the wind regimes there. It is suggested that the enhanced vertical motion during the descent of westerly regimes at the Equator might account for the observed downward propagation at sub-tropical latitudes. The heat budget is then examined with respect to the vertical motions suggested from momentum considerations. It is found that a heat sink in the equatorial stratosphere would be required to support the vertical motion field. It is shown that enhanced downward motion during the descent of westerly regimes (which the zonal wind data suggest) is necessary to keep the temperature field in geostrophic equilibrium with the wind field.
The Arabidopsis Intracellular Na+/H+ Antiporters NHX5 and NHX6 Are Endosome Associated and Necessary for Plant Growth and Development

Intracellular Na+/H+ antiporters (NHXs) play important roles in cellular pH and Na+ and K+ homeostasis in all eukaryotes. Based on sequence similarity, the six intracellular Arabidopsis thaliana members are divided into two groups. Unlike the vacuolar NHX1-4, NHX5 and NHX6 are believed to be endosomal; however, little data exist to support either their function or localization. Using reverse genetics, we show that whereas single knockouts nhx5 or nhx6 did not differ from the wild type, the double knockout nhx5 nhx6 showed reduced growth, with smaller and fewer cells and increased sensitivity to salinity. Reduced growth of nhx5 nhx6 was due to slowed cell expansion. Transcriptome analysis indicated that nhx5, nhx6, and the wild type had similar gene expression profiles, whereas transcripts related to vesicular trafficking and abiotic stress were enriched in nhx5 nhx6. We show that unlike other intracellular NHX proteins, NHX5 and NHX6 are associated with punctate, motile cytosolic vesicles, sensitive to Brefeldin A, that colocalize to known Golgi and trans-Golgi network markers. We provide data to show that vacuolar trafficking is affected in nhx5 nhx6. Possible involvements of NHX5 and NHX6 in maintaining organelle pH and ion homeostasis with implications in endosomal sorting and cellular stress responses are discussed.
Boronizing of electroplated steel

The process of boronizing steel takes different forms for steels plated with different metals. On nickel-plated specimens the structure of the boronized layer is normal. Layers of copper on specimen surfaces prevent boron from diffusing into the underlying steel, and may serve as a means of protecting non-working surfaces of articles in selective boronizing.
Government and Agricultural Adjustment

WHEN the new round of GATT negotiations start next month, negotiations on tariff and nontariff barriers on farm products will have a central and critical role. That role may be so critical that if little or no progress is made toward liberalizing trade in farm products, the negotiations will fail. Indeed the tide of isolationism and protectionism may well become so strong that recent trends toward increasing interferences with trade and other international economic relations, evident in the United States for the past five years, will win the day. It cannot be stressed too much that the strongest political support for trade liberalization in the United States comes from certain farm commodity interests. If these interests are thwarted once again, as they feel they were in the two previous GATT negotiations, they also are likely to turn inward. On many of these issues Canada and the United States find themselves in a similar situation. Both are industrial nations with less than 5 percent of their gross domestic product originating on farms. But because of the organization of their agricultures, based on highly effective divisions of labor and functions, served by efficient input industries and effective marketing services, the percentage of gross domestic product produced on farms greatly underestimates the trade significance of the production of farm commodities in each of the economies. Further, because of enormous amounts of land available, at least on a per capita basis, and the efficiency of their farms and the industries that are associated with farm commodities, in each of the two high income industrial countries farm products have a distinct comparative adva ta e. Thus both countries stand to lose if there is trade liberalization for nonfarm products and services and none for farm products since they would not have the opportunity to exploit the major comparative advantage that they possess in agriculture. So far as the GATT negotiations are concerned, the major international markets for the farm products of North America are in Western Europe and Japan. Unless Western Europe and Japan significantly modify their tariff and nontariff barriers affecting farm products, many of the possible gains from agriculture's comparative advantage in North America will not be realized.
Sequential predator effects across three life stages of the African tree frog, Hyperolius spinigularis

While theoretical studies of the timing of key switch points in complex life cycles such as hatching and metamorphosis have stressed the importance of considering multiple stages, most empirical work has focused on a single life stage. However, the relationship between the fitness components of different life stages may be complex. Ontogenetic switch points such as hatching and metamorphosis do not represent new beginnings—carryover effects across stages can arise when environmental effects on the density and/or traits of early ontogenetic stages subsequently alter mortality or growth in later stages. In this study, I examine the effects of egg- and larval-stage predators on larval performance, size at metamorphosis, and post-metamorphic predation in the African tree frog Hyperolius spinigularis. I monitored the density and survival of arboreal H. spinigularis clutches in the field to estimate how much egg-stage predation reduced the input of tadpoles into the pond. I then conducted experiments to determine: (1) how reductions in initial larval density due to egg predators affect larval survival and mass and age at metamorphosis in the presence and absence of aquatic larval predators, dragonfly larvae, and (2) how differences in mass or age at metamorphosis arising from predation in the embryonic and larval environments affect encounters with post-metamorphic predators, fishing spiders. Reduction in larval densities due to egg predation tended to increase per capita larval survival, decrease larval duration and increase mass at metamorphosis. Larval predators decreased larval survival and had density-dependent effects on larval duration and mass at metamorphosis. The combined effects of embryonic and larval-stage predators increased mass at metamorphosis of survivors by 91%. Larger mass at metamorphosis may have immediate fitness benefits, as larger metamorphs had higher survival in encounters with fishing spiders. Thus, the effects of predators early in ontogeny can alter predation risk even two life stages later.
Intracellular study of rat entopeduncular nucleus neurons in an in vitro slice preparation: response to subthalamic stimulation

Responses of rat entopeduncular nucleus (EP) neurons after stimulation of the subthalamic nucleus (STh) and the morphology of the EP neurons were studied using brain slice preparations. EP neurons were classified into two types based on their electrophysiological properties as reported previously. Of 87 EP neurons, 72 were Type I and the rest were Type II. Synaptic responses to STh stimulation were different in these two cell types. STh stimulation evoked excitatory postsynaptic potentials (EPSPs) followed by strong inhibitory postsynaptic potentials (IPSPs) in Type I neurons and EPSPs without strong IPSPs in Type II neurons. The EPSPs were considered to be monosynaptic because no large change in the latency (1.7 +/- 0.5 ms) resulted by alteration of stimulus intensity. The EPSPs were reversibly suppressed by kynurenic acid in a dose-dependent manner. Bath application of (+)-tubocurarine (10-50 microM) had no effect on EPSPs or IPSPs. Bath application of bicuculline methiodide (50-100 microM) markedly suppressed IPSPs evoked by STh stimulation and at the same time increased the amplitude and duration of EPSPs without affecting the latency. In the presence of bicuculline methiodide, EPSPs could induce plateau potentials and slow action potentials. Some type I and Type II neurons were intracellularly labeled by biocytin. Type I neurons were located throughout the EP but Type II neurons were located mainly in the dorsal portion of the EP. Medium sized somata of both Type I and Type II neurons were spine-free and fusiform or round in shape. They had 3-4 thick primary dendrites with diameters of 2-5 micron that branched into thin secondary dendrites.(ABSTRACT TRUNCATED AT 250 WORDS)
Scattered light photoelastic thermal stress analysis of a solid-propellant rocket motor.

This paper reports on the application of scattered light photoelasticity to stress analysis of solid propellants. The propellant model is made of polyurethane rubber cast with a starshaped internal boundary and case bonded to a hard epoxy motor case. The transition from model to prototype stress is direct, since the model material is similar to the binder material in existing propellants. Shrinkage stresses are induced in the model by a uniform temperature change that simulates conditions imposed on propellants in storage. The loaded propellant model is examined with a polarized laser light source. The resulting scattered fringe patterns and principal stress axes are observed and used to evaluate the stress distribution. The techniques employed in the model analysis are general and nondestructive; "live" loads (as opposed to the stress freezing technique) are used.
Insecure attachment in severely asthmatic preschool children: is it a risk factor?

Abstract This paper reports the results of attachment ratings for 26 severely asthmatic preschool children and 17 healthy children of similar age socioeconomic status, race, and sex. Additionally, behavioral problem scores were determined for each child by an independent interviewer using the Behavioral Screening Questionnaire. Forty-two percent of the asthmatic children were rated as insecurely attached compared with 14% of the comparison children. Differences in the behavioral scores among the securely attached asthmatic children, the insecurely attached asthmatic children, and the comparison children were examined. Statistically significant differences between all three groups were demonstrated. This report proposes that the quality of the child's attachment to the mother may serve as a potential risk or protective factor for the subsequent development of psychopathology.
Perceived warmth and skin temperature as functions of the duration and level of thermal irradiation

This study examined the correlations among the degree of perceived warmth. the level and duration of irradiant flux. and the thermal response of the skin. For any constant duration. perceived warmth grew as a power function of the difference between the irradiant flux of the stimulus and the flux that approximates the absolute threshold for warmth. The exponent of the power function was about 0.87 for the shortest durations (2—6 sec). but rose to 1.04 for the longest duration of exposure (12 sec). For any constant level of flux. perceived warmth changed only slightly with duration. In contrast, superficial skin temperature. and inferred temperatures of deeper layers of the skin, rose continuously and markedly with duration. Neither the change in tissue temperature. nor the rate of change of tissue temperature, nor thermal gradient correlated consistently with level of perceived warmth. The change in the difference between the temperature 0.2 mm and that 1.0 mm below the skin surface provided a fairly good but not perfect correlate to perceived warmth. The findings suggest the possibility that sensory adaptation at the site of the receptor system mediating warmth could act in such a way as nearly to offset the effect of rising skin temperature with increased duration ofstimulation.
Recombinant selves in mass mediated spacetime

Abstract Bakhtin proposed that novelistic “chronotopes” (depictions of place-time-and-personhood) implicitly frame readers’ acts of construing a novel’s plot and explicit content in ways that potentially transform everyday chronotopes presupposed by readers. Generalizing from the case of novels (and other genres of written discourse), this article develops an account of “cultural chronotopes,” namely depictions of place-time-and-personhood to which social interactants orient when they engage each other through discursive signs of any kind. Particular attention is given to a chronotope termed “mass mediated spacetime” and to a feature of subjectivity (the formation of “recombinant selves”) characteristic of the mass-mediated public sphere. The chronotopic phenomena explored in the seven accompanying articles (this issue) are discussed in the light of these proposals.
Reproductive timing in three southern Appalachian stream fishes

We quantified the reproductive biology of mottled sculpin (Cottus bairdi), rosyside dace (Clinostomus funduloides) and longnose dace (Rhinichthus cataractae) in Coweeta Creek, North Carolina, USA, a fifth order stream. These species are abundant in coldwater streams through out the southern Appalachian mountains, the southernmost limit of their range. We collected fishes from Coweeta Creek every second month (between July 1984 and January 1986) and quantified the seasonal reproductive cycles of females, using both histological techniques and the relative gonadal index (RGI). Both techniques indicated that I) C. bairdi reproduced between March and May, 2) CI. funduloides spawned between May and August and 3) R. cataractae were reproductively active between June and July. These conclusions were supported by the following: 1) the presence of reproductive coloration, 2) gravid females, 3) courtship displays, 4) the presence of nest-guarding C. bairdi males and 5) the timing of young-of-the-year recruitment. The reproductive characteristics of these 3 species were correlated with different environmental variables. The mean monthly RGI values for both C. bairdi and R. cataractae were inversely correlated with both maximum and minimum daily water temperatures. The mean RGI values for C. bairdi also were negatively correlated with photoperiod, whereas the values for R. cataractae and CI. funduloides were positively correlated with the change in daily photo period.
Passive mode-locking of a ruby laser using low-frequency stimulated brillouin scattering in birefingent crystals

Abstract A new technique of mode-locking Q -switched lasers using a birefringent crystal as an intracavity element is reported. Intense elastic waves are generated inside a birefringent crystal through the low-frequency, stimulated Brillouin scattering process and these in turn modulate the refractive index of the crystal and thus provide the necessary phase synchronization for mode-locking. Strong coupling between several neighboring modes of the laser is evidenced by the observation of high pulse repetition rates (several pulses circulating simultaneously within the cavity).
Stress as a predictor of the quality of parent-infant interactions.

Abstract Three predictor variables—vulnerability to stress, expectations for parenting stress, and low power attributions—were assessed for 21 couples during pregnancy. In-home observations of parent-infant interactions occurred 4 months postnatally. Stepwise multiple regression analyses, calculated separately for mothers and fathers, revealed that prenatal stress factors were more successful in predicting father-infant interactions. On the interaction variable basic care, 67% of the variance was explained by fathers' parenting stress expectations, stress vulnerability, and attributions for low power, whereas only 2% of the variance on basic care was explained by maternal scores on the same variables. Results of this study indicated that parent-infant interactions are affected by parental attitudes and personality characteristics. The present research also underscored the continued need to study the differential effects of gender on parent-infant interactions.
Immunochemical and biological studies with growth hormone in a pituitary extract of the coelacanth, Latimeria chalumnae Smith.

Abstract A substance immunochemically related to GH has been demonstrated in an extract of a pituitary from a coelacanth which is considered to be the sole surviving member of the ancient Crossopterygians. The findings were based on studies employing radioimmunoassay with an antiserum to turtle GH which was shown recently to be capable of detecting immunochemical relatedness of purified GHs from various vertebrate species with respect to those mammals. The results demonstrated that the coelacanth extract does contain a substance which shows a low, but significant degree of relatedness to GHs of tetrapods and to a substance immunochemically related to GHs in pituitary extracts of other existing primitive fishes including the lungfish, shark and sturgeon. Bioassay of the pituitary extract revealed that it was capable of a low, but significant degree of stimulation of growth promotion in a mammal on the basis of the rat tibia assay. The significance of the results is discussed.
Modeling test anxiety among men and women

Abstract Covariance structure modeling was used to test a model of test anxiety with a sample of 204 male and 412 female college students. Variables in the model included number of prior math courses, student course level, math self-concept, self-efficacy, achievement, and general and statistical test anxiety. Results indicated that whereas some paths differed across gender, these differences were not statistically significant according to tests of invariance. General and statistical test anxiety were found to be distinct, but related constructs, as seen in the differential relationships between these variables and other variables in the model. Lack of gender differences was discussed in light of previous research.
Micelle formation by sulfonates in a nonpolar solvent

Abstract The micellar properties of oil-soluble sulfonates in benzene have been studied by the fluorescence depolarization method. In moist benzene, the dinonylnaphthalene sulfonates of barium and sodium aggregate to form micelles of 7 to 8 and 12 to 13 monomers, respectively; the size of these micelles is not sensitive to water concentration. The critical range for micelle formation of these sulfonates is estimated at 1 × 10 −6 to 1 × 10 −7 formula weight per liter. A barium petroleum sulfonate was found to aggregate in micelles of 34 to 35 monomers. The difference between the sizes of micelles of the two types of sulfonates is explained in terms of the geometries of the respective monomers. The formation of Rhodamine B-sulfonate complexes has been observed, requiring a slight revision of previously developed methods for treatment of the data. The micellar nature of these substances in nonpolar solvents supports a previously published explanation of their effectiveness in reducing the corrosion potentials of acids in lubricating oils.
Non-Darwinian Evolution: A Critique

The view that most evolutionary changes in DNA need not be attributed to natural selection rests on several lines of evidence. This article argues that the evidence leads more simply to a neo-Darwinian interpretation.
An experimental study of laser supported hydrogen plasmas

The rudiments of a rocket thruster which receives its enthalpy from an energy source which is remotely beamed from a laser is described. An experimental study now partially complete is discussed which will eventually provide a detailed understanding of the physics for assessing the feasibility of using hydrogen plasmas for accepting and converting this energy to enthalpy. A plasma ignition scheme which uses a pulsed CO2 laser has been developed and the properties of the ignition spark documented, including breakdown intensities in hydrogen. A complete diagnostic system capable of determining plasma temperature and the plasma absorptivity for subsequent steady state absorption of a high power CO2 laser beam are developed and demonstrative use is discussed for the preliminary case study, a two atmosphere laser supported argon plasma.
Utilization of stereo in the freeze-fracture study of the ultrstructure of rat kidney cortex

Abstract Stereo electron micrographs have been used as an aid in examining the three-dimensional, functional structure of the mammalian rat kidney as shown in freeze-fracture. Tubular cells were observed which have a complex array of interdigitating membranes with two fracture faces, the P or protoplasmic face which is rich in membrane-intercalated particles and the E or exoplasmic face which has fewer particles. The relationships between large expanses of this membrane were clearly observed in stereo. The number, distribution, and structure of nuclear pores was visible and in glomerular epithelial cells, details of the orientation of the foot processes and pore spaces were shown with high resolution. The structure of the thin, fenestrated endothelial cells that form capillaries were particularly well-defined in three dimensions. Electron microscopy in stereo of kidney tissue facilitates study of the structure, and changes in structure, of this complex tissue.
Detection of antibodies against HLA-C epitopes in patients with rejected kidney transplants.

Abstract Background Although HLA-C matching is not considered in kidney transplantation, several reports have shown that anti-HLA-C antibodies are associated with rejection and graft failure. DNA-based typing methods can now accurately determine HLA-C compatibility and sensitive assays such as Luminex with single alleles can identify HLA-C antibodies. HLA-C displays considerable amino acid polymorphism that can be translated into a structurally defined epitope repertoire. Methods We have analyzed post-allograft nephrectomy sera from 45 HLA-C mismatched cases submitted by 15 laboratories worldwide participating in the 15th International Histocompatibility Workshop. All of them had HLA class I antibodies detected by a Luminex-based solid phase method using single-allele beads. This study addressed the determination of antibodies against donor HLA-C mismatches. Analysis of antibody reactivity patterns was performed using HLAMatchmaker, a structurally based matching program that considers 56 HLA-C eplets to define antibody-reactive epitopes. Many eplets shared by groups of HLA-C antigens, whereas others are also shared with HLA-A and/or HLA-B antigens. Results Twenty-seven patients (60%) had donor-specific HLA-C antibodies, significantly less than the donor-specific antibodies induced by HLA-A and HLA-B mismatches. HLA-C antibody responses correlated with the eplet loads of the HLA-C mismatches. There were 352 instances whereby a donor HLA-C eplet was mismatched and for 84 (24%) of them there was antibody reactivity with a particular eplet (69 instances) or an eplet pair (15 instances). The latter generally consisted of mismatched eplets paired with self-eplets shared between the immunizing HLA-C alleles and HLA alleles of the patient. Several HLA-C eplets exhibited a relatively high immunogenicity as evidenced by their frequencies of specific antibodies. Conclusion These findings demonstrate the importance of HLA-C mismatching in humoral sensitization and that HLA-C epitopes can induce specific antibodies. They illustrate the usefulness of HLAMatchmaker in understanding donor-specific antibody reactivity patterns and the determination of HLA mismatch acceptability when transplantation is considered.
Intermediate- to high-energy positrons scattered by alkali-metal atoms

We present calculations of the differential, integrated elastic, and total cross sections for positrons scattered from alkali-metal atoms. The energy of the positrons ranges from 10 eV to 1000 eV. In the calculations we use parameter-free model potentials for the correlation-polarization and absorption interactions. The absorption potential used for positron scattering is based on a quasifree model that we recently proposed and tested for the noble-gas targets. For positron--alkali-metal scattering the model potentials have produced reliable scattering cross sections over the extended range of impact energies when compared against the available experimental data.
Identifying Components of a Successful Faculty-Advisor Program.

While research models show that faculty advisors play an important role in academic advising, the data are limited regarding faculty conceptualization of their roles and responsibilities as advisors. In this study, we gather faculty perspectives about the components that have made the model effective in a large, urban, community college. Faculty members describe their strategies for developing student accountability, goal-setting abilities, and decision-making skills. They also discuss strategies for building student academic success and encouraging student self-regulation and self-determination. The described program has helped increase buy-in from faculty members undertaking advising via systematized delivery. The faculty feedback will help others design and implement advising programs proven to increase persistence and reduce attrition.
Tonnages, Medieval and Modern

onnages are of prime importance in economic history not only in estimating changes in the shipping industry's own, employment of men and resources but also in estimating the relative importance of various trade routes and the relative prosperity of various periods. To evaluate the figures used in such comparisons it is essential to know what is meant by a 'ton'. Too often historical studies refer to 'tonnage' without making clear what is meant, although the word has meanings so different one from another that a ship's tonnage measured in a ton of one kind is often two or three times its tonnage measured in a different kind of ton. The ordinary man in the street thinks first of a weight. Perhaps in America he thinks first of the short ton of 2,000 lbs., but let us hope he thinks of what is called in Britain and America the long ton of 2,240 lbs., for long tons are the measure of weight used with reference to ships. The metric ton of Iooo kg. is practically the same as the long ton (I m.t. 2,240o6 lbs. avoirdupois and I long ton oIoI6 m.t.). The best way to compare medieval and early modern statistics of shipping, it will here be argued, is to convert them as far as possible into estimates of carrying capacity measured in metric tons, or into deadweight tonnage. Since conversion is often difficult, historians are justified in repeating what they find in their sources even if they are unable to say what kind of a 'ton' is meant, so long as they make clear what they are doing. Whenever the same unit is used for all the figures in a set, comparison may be valuable within the set. Wider comparisons, however, require identification of the units used and conversion to a common denominator.1 Unfortunately different kinds of modern
Experimental verification of thermal switch effectiveness in thermoelectric energy harvesting

This paper presents research seeking to experimentally verify the effectiveness of a thermal switch used in series with thermoelectric devices for waste heat recovery for constant and variable source heat input and for variable source thermal capacitance (mass). Using an experimental setup composed serially of a fixed heat source, a variable thermal resistance air gap serving as a thermal switch, a thermoelectric device, and a heat sink, the time-averaged power output to power input ratios improved up to 15% and 30%, respectively, for constant and variable heat input in certain design space conditions. The experimental results, as supported by model predictions, suggest that the thermal capacitance of the heat source must be greater than the thermal capacitance of the thermoelectric device in order for thermal switching to improve the time-averaged power output to power input ratios of waste heat recovery systems. The results have direct application to aircraft energy harvesting.
Modification of the human visual evoked potential by monochromatic backgrounds.

Abstract Monochromatic flicker stimuli (17.5 Hz) were delivered to the human eye in the presence of steady monochromatic backgrounds of equal photopic luminance. The average visual evoked potential was recorded from the scalp. Under most conditions involving a large difference in wavelengths of stimulus and background, the responses were found to be from 1 -5 to 3 times larger than those evoked by superimposing the same stimulus on a background of identical wavelength. The responses evoked by heterochromatic stimulus-background combinations were often larger than the responses elicited by the same stimulus when no background was present. The presence of a background of the same wavelength as the stimulus usually reduced the size of response. Wavelength-dependent temporal effects were also found. Backgrounds of equal photopic luminance caused shifts as large as 0.5 cycle in the phase relationship of the response wave to the stimulus flash when the test stimulus was kept constant and the background wavelength varied. It is concluded that there are components of the evoked potential which differ in spectral sensitivity and that some of these components also differ in the time domain.
Influence of priority effects and pond location on invaded larval amphibian communities

In Florida, the Cuban Treefrog (Osteopilus septentrionalis) is a superb colonist and appears to be a significant driver of amphibian community dynamics. Decline of native anurans has been linked to possible competition with adult O. septentrionalis but interactions during the larval stage are largely unknown. Rearing O. septentrionalis tadpoles along with two native anurans, the Squirrel Treefrog (Hyla squirella) and the Southern Toad (Bufo terrestris) in both experimental artificial ponds and laboratory aquaria, the role of competition as the mechanism driving the dynamics of invaded amphibian communities in Florida was examined. Also examined was the role of priority effects and variation between pond locations in altering interactions between O. septentrionalis and native anuran larvae. Interspecific competition was strong during the larval stage; the presence of O. septentrionalis reduced larval performance and survival of native anurans. Pond location alone had little effect on interspecific interactions, but priority effects were strong. Pond location and priority effects acted together to influence species interactions. The selective influence of different interaction modifiers acted to increase or decrease the impacts of exotic species on native taxa.
A simple method for stem cell labeling with fluorine 18.

Abstract Hexadecyl-4-[ 18 F]fluorobenzoate ([ 18 F]HFB), a long chain fluorinated benzoic acid ester, was prepared in a one-step synthesis by aromatic nucleophilic substitution of [ 18 F]fluoride ion on hexadecyl-4-( N , N , N -trimethylammonio)benzoate. The radiolabeled ester was obtained in good yields (52% decay corrected) and high purity (97%). [ 18 F]HFB was used to radiolabel rat mesenchymal stem cells (MSCs) by absorption into cell membranes. MicroPET imaging of [ 18 F]HFB-labeled MSCs following intravenous injection into the rat showed the expected high and persistent accumulation of radioactivity in the lungs. [ 18 F]HFB is thus simple to prepare and uses labeling agent for short-term distribution studies of injected stem cells.
Function of murine adenosine deaminase in the gastrointestinal tract.

Adenosine deaminase (ADA) deficiency in humans leads to a combined immunodeficiency characterized by severe T and B cell lymphopenia. ADA-deficient humans also display defective development of gut-associated lymphoid tissues (GALT). They lack lymphoid cells, and the Peyer's patches are without germinal centers. In mice, ADA-deficient fetuses die perinatally due to liver damage, but they also exhibit pathology in the thymus, spleen, and the small intestine. The GI phenotype associated with ADA-deficient humans prompted us to examine the effect of ADA-deficiency on mouse small intestine tissue. The work presented here focuses on understanding the physiological role of ADA in the GI tract, using ADA-deficient mice rescued from perinatal lethality by restoring Ada expression to trophoblast cells. Histologically and immunologically, the GALT was compromised at all sites in ADA-/- mice, with the most dramatic changes seen in the Peyer's patches. Profound disturbances in purine metabolism were detected in all the gastrointestinal tissues. In particular, adenosine and deoxyadenosine, the ADA substrates, increased markedly while the product inosine decreased. The activity of S-adenosylhomocysteine hydrolase decreased throughout the GI tract, indicating a possible disruption of cellular transmethylation and activation of apoptotic pathways. There were also disturbances in the purine metabolic pathway with a decrease in the production of downstream nucleosides hypoxanthine and xanthine.
Developmental differences in cortical and hippocampal vulnerability to intermittent hypoxia in the rat

Obstructive sleep apnea is characterized by intermittent hypoxic events during sleep, and is associated with substantial neurocognitive morbidity, particularly in children. Intermittent hypoxia (IH) leads to increases in apoptosis in the cortex and hippocampus of the adult rat, peaking at 48 h of exposure. To examine whether the susceptibility to IH exhibits developmental differences, rats were exposed to 48 h of IH at ages 2, 5, 10, 15, 20, 25, 30, 60, and 120-day postnatally, and apoptosis was determined by terminal deoxy-nucleotidyl transferase-mediated in situ end labeling and immunohistochemical staining for single-stranded DNA. Although IH induced apoptosis at all postnatal ages, smaller increases were apparent in 2 and 5-day old (P < 0.01 vs. any other age) while peak apoptosis occurred at 10-25 days (P < 0.001 vs. 30, 60, and 120 days). We conclude that a unique window of vulnerability to IH is present in the cortex and hippocampus during post-natal maturation, and may underlie the high frequency of neurobehavioral deficits associated with obstructive sleep apnea in children.
Non-parametric tests of portfolio efficiency under static and dynamic conditions

A set of non-parametric tests which includes the stochastic dominance criteria is developed here for evaluating the performance of mutual fund portfolios in relation to the market index. The empirical results support the hypothesis that some funds tend to dominte the market on the average, when a second-order stochastic dominance criterion is used.
Note on reliability of the Carlson Psychological Survey.

Szrnzrnary.-The Carlson Psychological Sunrey is designed to assess and classify criminal offenders but its rehability has not been estimated for use with female adolescents. The survey was adminisrered to 36 female adjudicated delinquents benveen the ages of 14 and 16 years and readministered after a 2-wk. intend to estimate testretest reliability. Support for its stability over 2 wk. with this specific adolescent population was obtained. The Carlson Psychological Survey was srandardized for use in the assessment and classification of criminal offenders (Carlson, 1981, 1997). It is a 50-item questionnaire requiring a fourth grade reading level and is comprised of €our subscales assessing various areas of functioning. The subscales are Chemical Abuse, Thought Disorder, Antisocial Tendencies, and Self-depreciation. Carlson noted that the scale is intended for use with adult and adolescent offenders but reliability data in the manual are only noted for adult offenders; test-retest stabilities over 2-wk. intervals were .91 for Chemical Abuse, .92 for Thought Disorder, and .89 and .87 for Antisocial Tendencies and Self-depreciation, respectively (Carlson, 1997). To examine whether the sunfey was also appropriately reliable for use with adolescent offenders, DeFrancesco (2000) conducted a study on a group of male adolescent offenders and obtained reliability coefficients, similar to those obtained by Carlson (1981, 1997), of .91 for Chemical Abuse, .86 for Thought Disorder, .94 for Antisocial Tendencies, and .81 for Self-depreciation, suggesting that the survey could be used with male adolescent offenders. The current study employed the same methodology to assess the survey's test-retest reliabhty for female adolescent offenders. It was administered to 37 female offenders residing in a juvenile detention facility as part of the intake assessment process and again after 2 wk. Subjects of mean age of 14.2 yr. were 38% AErican American, 34% Euro-American, 23% Hispanic. and 5% Other. Test-retest reliability coefficients were .87 for Chemical Abuse, .88 for Thought Disorder, .91 for Antisocial Tendencies, and .90 for Self-depreciation and comparable to prior estimates (Carlson, 1981, 1997; DeFrancesco, 2000) for other groups. These indicate that the survey can be used with reasonable confidence not only xvith adult and adolescent male offenders but with adolescent female offenders as well.
THE CAPACITY OF THE RENAL VASCULAR BED IN HYPERTENSION

By using kerosene and avoiding postmortem rigor one can obtain perfusion rates in kidneys nearly five times faster than those reported by observers who perfused kidneys immediately post mortem with saline solution, only half as viscous as kerosene. The results obtained by kerosene perfusion indicate possible renal blood flow 50 to 100 per cent greater than that measured by Smith and his coworkers (7) in living men by diodrast clearance under normal conditions, and about as high as those observed in febrile subjects. Like the diodrast method, kerosene perfusion shows a striking decrease in renal vascular bed between early matuity (age 18 to 35) and senescence (45 to 60). This decrease is about 25 per cent. Most kidneys from patients with hypertension without uremia have vascular beds in the normal range, but a few show great decreases in capacity for blood flow. This evidence is interpreted as another indication that renal arteriosclerosis is often a result, rarely a cause of hypertension. Significant occlusion of large renal arteries is rare. Uremia due to amyloid may occur with no significant decrease in renal vascular bed, but the uremia of renal sclerosis, glomerulo- or pyelonephritis is associated with reduction of vascular bed to very low levels.
Breakdown limits on Gigavolt-per-meter electron-beam-driven wakefields in dielectric structures.

First measurements of the breakdown threshold in a dielectric subjected to GV/m wakefields produced by short (30-330 fs), 28.5 GeV electron bunches have been made. Fused silica tubes of 100 {micro}m inner diameter were exposed to a range of bunch lengths, allowing surface dielectric fields up to 27 GV/m to be generated. The onset of breakdown, detected through light emission from the tube ends, is observed to occur when the peak electric field at the dielectric surface reaches 13.8 {+-} 0.7 GV/m. The correlation of structure damage to beam-induced breakdown is established using an array of postexposure inspection techniques.
Gene 33 Is an Endogenous Inhibitor of Epidermal Growth Factor (EGF) Receptor Signaling and Mediates Dexamethasone-induced Suppression of EGF Function

We report a mechanism by which the adapter protein Gene 33 (also called RALT and MIG6) regulates epidermal growth factor receptor (EGFR) signaling. We find that Gene 33 inhibits EGFR autophosphorylation and specifically blunts epidermal growth factor (EGF)-induced activation and/or phosphorylation of Ras, ERK, JNK, Akt/PKB, and retinoblastoma protein. The Ack homology domain of Gene 33, which contains the previously identified EGFR binding domain, is both necessary and sufficient for this inhibition of EGFR autophosphorylation. The endogenous Gene 33 polypeptide is induced by EGF, platelet-derived growth factor, serum, and dexamethasone (Dex) in Rat 2 rat fibroblasts. Dex induces Gene 33 expression and inhibits EGFR phosphorylation and EGF signaling. RNA interference-mediated silencing of Gene 33 significantly reverses this effect. Overexpression of Gene 33 completely blocks EGF-induced protein and DNA synthesis in Rat 2 cells, whereas gene 33 RNA interference substantially enhances EGF-induced protein and DNA synthesis in Rat 2 cells. Our results indicate that Gene 33 is a physiological feedback inhibitor of the EGFR, functioning to inhibit EGFR phosphorylation and all events induced by EGFR activation. Our results also indicate a role for Gene 33 in the suppression, by Dex, of EGF signaling pathways. We propose that Gene 33 may function in the cross-talk between EGF signaling and other mitogenic and/or stress signaling pathways.
Perturbative tests of a lattice fermion proposal of Quinn and Weinstein

We discuss a proposal of Quinn and Weinstein for incorporating fermions into lattice gauge theory and analyze it in the context of weak-coupling perturbation theory. In two dimensions we find that, because of a special property of the Hamiltonian formulation, one recovers the physics of the continuum theory as the lattice spacing tends to zero. In four dimensions we find that the transverse photon develops a quadratically divergent mass. Consequently, in order to obtain a satisfactory continuum limit, one would need to augment the Quinn-Weinstein proposal through the inclusion of additional counterterms. We argue that the construction of such counterterms would entail at least a partial breaking of the chiral symmetry.