bluuebunny/crossref_metadata_2025 huggingface dataset:
The overall rates of dominant and recessive lethal and visible mutation induced by spermatogonial X-irradiation of mice
Authors: Lyon Mary F. , Phillips Rita J. S. , Searle A. G.
Published: September 2009

1. Hybrid (C3H♀ × 101♂) male mice were given two doses of 600 r. acute x-irradiation eight weeks apart and outcrossed at the end of their sterile period. Their fully fertile sons were outcrossed and daughters of these sons were backcrossed to them, in order to study the rates of induction in spermatogonia of dominant and recessive lethal and visible mutations, as well as dominant semi-sterility.

2. F1litter-size decreased by 15·2% at birth and 15·8% at weaning age, as compared with controls. This decrease was very largely due to dominant lethality acting at about the time of embryonic implantation. There was also a highly significant increase in the incidence of heritable semi-sterility, the estimated rate of induction of reciprocal translocations being 3·3% per gamete.

3. The dominant lethality was shown to be partly a secondary consequence of induced translocation heterozygosis. The estimated overall rate of dominant lethal induction was 10·6% per gamete, with ‘primary’ dominant lethals induced at a rate of 4·0% per gamete.

4. The estimated mutation rate to dominant visible mutations was 4·6 × 10-7/gamete/r., but this was based on only two mutations in the irradiated series.

5. In the backcross generation there was again significantly more embryonic death in the irradiated series, mainly at the small mole stage and this was attributed to induced lethal mutation. The survival in the irradiated series was 96·80% of that in the controls and from this the rate of induction of recessive lethals was calculated to be 2·5 × 10-4/gamete/r. There was no evidence of the induction of lethals acting later than 14 days' gestation.

6. The estimated rate of induction of recessive visible mutations was 1·8 × 10-5/gamete/r., but the results showed heterogeneity, probably due to personal factors.

7. No significant sex-ratio differences were found.

8. The results were compared with those of specific locus and other relevant experiments. The rates of induction of recessive lethal mutations and of recessive visibles were both lower than might have been expected. On these results the mouse was only 4–5 times more sensitive thanDrosophilato the mutagenic effects of radiation.
A sex-linked anaemia in the mouse
Authors: Grewal Manjit Singh
Published: September 2009

A sex-linked recessive anaemia (symbolsla) in the mouse is responsible for a rather uncharacteristic blood picture which persists virtually unchanged throughout life. The red cell count is reduced to about three-quarters of the normal value, the cells produced differ from normal ones by a slight reduction in the mean corpuscular Hb concentration and a slight reduction in the mean cell volume. As the mean cell diameter is more strongly reduced, it is concluded that the cells must be thicker than normal. There is a reduction of haemopoietic tissue both in the liver and in the bone marrow.
Genetic localization and phenotypic expression of X-linked cataract (Xcat) in Mus musculus
Authors: Favor Jack , Pretsch Walter
Published: September 2009

Linkage data relative to the markers tabby and glucose-6-phosphate dehydrogenase are presented to locate X-linked cataract (Xcat) in the distal portion of the mouse X-chromosome between jimpy and hypophosphatemia. The human X-linked cataract-dental syndrome, Nance–Horan Syndrome, also maps closely to human hypophosphatemia and would suggest homology between mouse Xcat and human Nance-Horan Syndrome genes. In hemizygous males and homozygous females penetrance is complete with only slight variation in the degree of expression. Phenotypic expression in Xcat heterozygous females ranges from totally clear to totally opaque lenses. The phenotypic expression between the two lenses of a heterozygous individual could also vary between totally clear and totally opaque lenses. However, a correlation in the degree of expression between the eyes of an individual was observed. A variegated pattern of lens opacity was evident in female heterozygotes. Based on these observations, the site of gene action for the Xcat locus is suggested to be endogenous to the lens cells and the precursor cell population of the lens is concluded to be small. The identification of an X-linked cataract locus is an important contribution to the estimate of the number of mutable loci resulting in cataract, an estimate required so that dominant cataract mutagenesis results may be expressed on a per locus basis. The Xcat mutation may be a useful marker for a distal region of the mouse X-chromosome which is relatively sparsely marked and the X-linked cataract mutation may be employed in gene expression and lens development studies.
Expression of threet-complex genes,Tcp-1, D17Leh117c3, andD17Leh66, in purified murine spermatogenic cell populations
Authors: Willison K. R. , Hynes G. , Davies P. , Goldsborough A. , Lewis V. A.
Published: September 2009

Transmission ratio distortion (TRD) is a property of the completet-haplotype which results in the preferential transmission of thet-haplotype chromosome from heterozygoust/+ males to the majority of the progeny. Available data suggest that int/+ males, a dysfunction of the wild-type sperm within the female reproductive tract is responsible for the observed deviation from Mendelian segregation ratios. Genetically, Lyon has shown that multiple loci within thet-complex are required for maximum levels of TRD. These loci include multiplet-complex distorters (Teds) which act upon a singlet-complex responder (Ter). Testis-expressed genes have been cloned which map to the same subregions of thet-complex as theTedsandTerand are thus considered candidate genes for the products of these loci. To begin to understand how the products of these loci biochemically control TRD, the expression of three TRD-candidate genes (Tcp-1, D17Leh117c3, andD17Leh66) has been determined in populations of spermatocytes and differentiated spermatids purified to near homogeneity by unit gravity sedimentation. Fractions covering the entire gradient were analysed resulting in a more accurate picture of the precise timing of expression than previously reported. Transcription of all three genes was up-regulated in pachytene primary spermatocytes and persisted at stable levels through the haploid spermatid stages. Significantly, only levels of mRNA encoded byD17Leh66, the candidate gene forTcr, increased from early round to elongating-stage spermatids. If this pattern of expression does, in fact, representTcr, these data provide the first direct evidence that wild-type andt-haplotypeTcrelements could be differentially expressed in haploid spermatids.
Genetics of alcohol dehydrogenase and aldehyde dehydrogenase fromMonodelphis domesticacornea: further evidence for identity of corneal aldehyde dehydrogenase with a major soluble protein
Authors: Holmes Roger S. , van Oorschot Roland A. H. , Vandeberg John L.
Published: September 2009

A didelphid marsupial, the gray short-tailed opossum (Monodelphis domestica), was used as a model species to study the biochemical genetics of alcohol dehydrogenases (ADHs) and aldehyde dehydrogenase (ALDH) in corneal tissue. Isoelectric point variants of corneal ALDH (designated ALDH3) and a major soluble protein in corneal extracts were observed among eight families of animals used in studying the genetics of these proteins. Both phenotypes exhibited identical patterns following PAGE-IEF and were inherited in a normal Mendelian fashion, with two alleles at a single locus (ALDH3) showing codominant expression. The data provided evidence for genetic identity of corneal ALDH with this major soluble protein, and supported biochemical evidence, recently reported for purified bovine corneal ALDH, that this enzyme constitutes a major portion of soluble corneal protein (Abediniaet al.1990). Isoelectric point variants for corneal ADH were also observed, with patterns for the two major forms (ADH3 and ADH4) and one minor form (ADH5) being consistent with the presence of two ADH subunits (designated γ and δ), and variant phenotypes existing for the γ subunit. The genetics of this enzyme was studied in the eight families, and the results were consistent with codominant expression of two alleles at a single locus (designatedADH3). It is relevant that a major detoxification function has been proposed for corneal ADH and ALDH, in the oxidoreduction of peroxidic aldehydes induced by available oxygen and UV-B light (Holmes & VandeBerg, 1986a). In addition, a direct role for corneal ALDH as a UV-B photoreceptor in this anterior eye tissue has also been proposed (Abediniaet al.1990).
Reliability of the bulk milk somatic cell count as an indication of average herd somatic cell count
Authors: Lievaart Jan , Barkema Herman W , Hogeveen Henk , Kremer Wim
Published: September 2009

Bulk milk somatic cell count (BMSCC) is a frequently used parameter to estimate the subclinical mastitis prevalence in a dairy herd, but it often differs considerably from the average SCC of all individual cows in milk. In this study, first the sampling variation was determined on 53 dairy farms with a BMSCC ranging from 56 000 to 441 000 cells/ml by collecting five samples on each farm of the same bulk tank. The average absolute sampling variation ranged from 1800 to 19 800 cells/ml. To what extent BMSCC represents all lactating cows was evaluated in another 246 farms by comparing BMSCC to the average herd SCC corrected for milk yield (CHSCC), after the difference was corrected for the sampling variation of BMSCC. On average BMSCC was 49 000 cells/ml lower than CHSCC, ranging from −10 000 cells/ml to 182 000 cells/ml, while the difference increased with an increasing BMSCC. Subsequently, management practices associated with existing differences were identified. Farms with a small (<20%) difference between BMSCC and CHSCC administered intramuscular antibiotics for the treatment of clinical mastitis more often, used the high SCC history when cows were dried off more frequently and had a higher number of treatments per clinical mastitis case compared with farms with a large (⩾20%) difference. Farms feeding high-SCC milk or milk with antibiotic residues to calves were 2·4-times more likely to have a large difference. Although sampling variation influences the differences between BMSCC and CHSCC, the remaining difference is still important and should be considered when BMSCC is used to review the average herd SCC and the subclinical mastitis prevalence.
Sense of hyper-positive self, goal-attainment beliefs and coping strategies in bipolar I disorder
Authors: Lee R. , Lam D. , Mansell W. , Farmer A.
Published: September 2009

Background

There is some evidence that cognitive therapy (CT) is beneficial in reducing relapses in bipolar disorder. However, not all bipolar patients benefit from it. A previous study found that a group of non-responders to CT shared common characteristics: they value some of the high goal-attainment beliefs and characteristics associated with being in a state of mild hypomania – a high ‘sense of hyper-positive self’ (SHPS). To promote of our understanding of this group of patients, the present study investigated the relationship between SHPS, preferred internal state, dysfunctional attitudes and coping with hypothetical manic prodromal scenarios.

Method

Fifty-four bipolar I patients filled in self-report questionnaires that assess preferred mood state, coping with scenarios, dysfunctional attitudes and SHPS.

Results

The Sense of Hyper-positive Self Scale Ideal score (SHPSS-Ideal) predicted patients' preferred internal state of mania. Coping with hypothetical scenarios was predicted by Dysfunctional Attitude Scale (DAS) goal-attainment scores: the higher the goal-attainment score, the higher the participant's tendency to identify with self-descriptors linked to hypomania and to engage in stimulating behaviours that may escalate the prodromal stage to mania.

Conclusions

Clinicians should check and modify goal-attainment beliefs, particularly of those who exhibit features of SHPS. These patients' tendency to identify with hypomanic traits as self-descriptors should be dealt with by psychological techniques such as cognitive restructuring.
Social anxiety disorder and alcohol use disorder co-morbidity in the National Epidemiologic Survey on Alcohol and Related Conditions
Authors: Schneier F. R. , Foose T. E. , Hasin D. S. , Heimberg R. G. , Liu S.-M. , Grant B. F. , Blanco C.
Published: September 2009

Background

To assess the prevalence and clinical impact of co-morbid social anxiety disorder (SAD) and alcohol use disorders (AUD, i.e. alcohol abuse and alcohol dependence) in a nationally representative sample of adults in the United States.

Method

Data came from a large representative sample of the US population. Face-to-face interviews of 43093 adults residing in households were conducted during 2001–2002. Diagnoses of mood, anxiety, alcohol and drug use disorders and personality disorders were based on the Alcohol Use Disorder and Associated Disabilities Interview Schedule – DSM-IV version.

Results

Lifetime prevalence of co-morbid AUD and SAD in the general population was 2.4%. SAD was associated with significantly increased rates of alcohol dependence [odds ratio (OR) 2.8] and alcohol abuse (OR 1.2). Among respondents with alcohol dependence, SAD was associated with significantly more mood, anxiety, psychotic and personality disorders. Among respondents with SAD, alcohol dependence and abuse were most strongly associated with more substance use disorders, pathological gambling and antisocial personality disorders. SAD occurred before alcohol dependence in 79.7% of co-morbid cases, but co-morbidity status did not influence age of onset for either disorder. Co-morbid SAD was associated with increased severity of alcohol dependence and abuse. Respondents with co-morbid SAD and alcohol dependence or abuse reported low rates of treatment-seeking.

Conclusions

Co-morbid lifetime AUD and SAD is a prevalent dual diagnosis, associated with substantial rates of additional co-morbidity, but remaining largely untreated. Future research should clarify the etiology of this co-morbid presentation to better identify effective means of intervention.
FISCAL POLICY AND ECONOMIC DEVELOPMENT
Authors: Mourmouras Alexandros , Rangazas Peter
Published: September 2009

This paper offers possible explanations for three generally observed facts about fiscal policy and development: (F1) the relative size of government increases as an economy develops, (F2) the rise in government and taxation are associated with rising or constant economic growth rates, and (F3) today's developing countries have larger government sectors than today's developed countries had at similar stages of development. The explanations for these facts are based on the structural transformation from traditional to modern production, rising public infrastructure investment, and less democratic governments in many of today's developing economies.
HABIT FORMATION IN AN INTERDEPENDENT WORLD ECONOMY
Authors: Ikeda Shinsuke , Gombi Ichiro
Published: September 2009

In a two-country world economy, endogenous interest rate adjustment makes one country's consumption-habit dynamics affected by the other country's habit. External indebtedness depends crucially on international differences in habit-adjusted net output less habitual living standard. Interest rate adjustment enlarges the consumption impact of an income shock. Consistent with the empirical facts, the habit parameter of a large country would thus be underestimated, and the current account volatility overestimated, if they were estimated using a small-country model. An increase in fiscal spending in one country can benefit the country and harm the neighbor one due to reversed intertemporal terms-of-trade effects.
PRODUCTIVITY CONVERGENCE ACROSS INDUSTRIES AND COUNTRIES: THE IMPORTANCE OF THEORY-BASED MEASUREMENT
Authors: Inklaar Robert , Timmer Marcel P.
Published: September 2009

Cross-country studies of economic growth have been hampered by the scarcity of reliable data on productivity at the industry level; see Bernard and Jones [American Economic Review, 91 (4) (2001), 1168–1169] and Rogerson [Journal of Political Economy, 116 (2) (2008), 235–259]. We bring together literature on industry prices, human capital, and capital assets to construct industry-level productivity measures that are well grounded in neoclassical production theory. These theory-based measures differ widely from the crude measures commonly used in the literature. We use these to confirm and strengthen the finding of Bernard and Jones [American Economic Review, 86 (5) (1996), 1216–1238] that for advanced OECD countries, patterns of convergence across sectors have differed since 1970: whereas productivity in market services converged, there is no convergence in manufacturing. More detailed analysis confirms that patterns of convergence are highly industry-specific. There is no dominant convergence trend in sectoral productivity growth across advanced countries.
RECENT DEVELOPMENTS IN THE INTERNATIONAL COMPARISON OF PRICES AND REAL OUTPUT
Authors: Hill Robert J. , Hill T. Peter
Published: September 2009

Three important current areas of research in the field of international comparisons are the construction of price indexes at the basic heading level, price indexes at higher levels of aggregation, and the linking of comparisons across regions. We consider recent innovations in each of these areas. These innovations have largely arisen out of International Comparisons Program (ICP) 2005, and hence we discuss them in this context. We give particular emphasis to the construction of price indexes at the basic heading level, because we believe it is here that the biggest problems lie. For example, the apparently anomalous results obtained for China and India in ICP 2005 can be traced back to problems at the basic heading level. We also highlight some inconsistencies in current ICP methodology and some promising areas for future research that warrant closer scrutiny in the next round of ICP.
CONSISTENT COMPARISONS OF REAL INCOMES ACROSS TIME AND SPACE
Authors: Feenstra Robert C. , Ma Hong , Rao D. S. Prasada
Published: September 2009

Consistent real income comparisons over time and space are critical for studies on catch-up and convergence. The paper provides an analytical framework for making real income comparisons across countries and over time that satisfy transitivity and at the same time reflect an underlying nonhomothetic utility function for a representative consumer. The concept of reference price comparisons is developed and implemented using nonhomothetic translog and almost ideal demand systems. The paper discusses adirect approach, which uses all the parameters of the demand system to make real income comparisons, and anindirect approach, which adjusts the national price-based comparisons using reduced information only on income elasticities of demand. The proposed approach is empirically implemented using data from the 1980 and 1996 benchmark data from the International Comparison Program, and the empirical results confirm the analytical results discussed in the paper.
INTRODUCTION TOMEASUREMENT WITH THEORY
Authors: Barnett William A. , Diewert W. Erwin , Zellner Arnold
Published: September 2009

This paper is the introduction to theMacroeconomic DynamicsSpecial Issue on Measurement with Theory. The Guest Editors of the special issue are William A. Barnett, W. Erwin Diewert, Shigeru Iwata, and Arnold Zellner. The papers included are part of a larger initiative to promote measurement with theory in economics.
ADMISSIBLE CLUSTERING OF AGGREGATOR COMPONENTS: A NECESSARY AND SUFFICIENT STOCHASTIC SEMINONPARAMETRIC TEST FOR WEAK SEPARABILITY
Authors: Barnett William A. , de Peretti Philippe
Published: September 2009

In aggregation theory, the admissibility condition for clustering components to be aggregated is blockwise weak separability, which also is the condition needed to separate out sectors of the economy. Although weak separability is thereby of central importance in aggregation and index number theory and in econometrics, prior attempts to produce statistical tests of weak separability have performed poorly in Monte Carlo studies. This paper introduces a new class of weak separability tests, which is seminonparametric. Such tests are both based on a necessary and sufficient condition and are fully stochastic, allowing to take into account measurement error. Simulations show that the tests perform well, even for large measurement errors.
Fragmentation or interaction: the WTO, fisheries subsidies, and international law
Authors: YOUNG MARGARET A.
Published: September 2009

Subsidies to the fishing sector have trade and ecological consequences, especially for fisheries that are over-exploited. In response, WTO members are negotiating to clarify and improve the Agreement on Subsidies and Countervailing Measures. Yet significant legal challenges constrain this ongoing effort because fisheries conservation and management matters are often addressed by the United Nations Convention on the Law of the Sea, instruments of the Food and Agriculture Organization, and other legal regimes to which some WTO members have not consented. This article analyses modes of learning and information exchange within the WTO regime, and compares the proposed use of standards, benchmarks, and peer review in the draft fisheries subsidies rules with existing arrangements between the WTO and organizations such as the OECD and product standard-setting bodies. It argues that novel deliberative strategies of regime interaction are more important in resolving the challenges posed by international law's fragmentation than adherence to strict mandates or legal hierarchies.
Mixing on the continental slope of the southern Weddell Sea
Authors: Daae Kjersti L. , Fer Ilker , Abrahamsen E. Povl
Published: September 2009

Shipboard hydrography and current profiles collected in 2003 and time series from moored current meters deployed in late 1990s are analyzed to study the variability of mixing in the southeastern Weddell Sea. Profiles of eddy diffusivity Kρ are inferred from fine‐scale shear (vertical derivative of horizontal velocity) and strain (vertical derivative of isopycnal displacement) variance using parameterizations which relate the internal wave energy to the dissipation rate at small scales. The highest mixing rates are seen near the bottom where the eddy diffusivities are elevated by 1 order of magnitude from those in the interior and exceed 10−4 m2 s−1. The observations show latitudinal variability in Kρ, particularly near the bottom, where Kρ significantly increases near 74° 28′S, the critical latitude for lunar semidiurnal (M2) tides. In this region, the critical latitude coincides with near‐critical topography on the upper continental slope, a situation which favors generation of M2 internal waves. Consistent with the results from fine‐scale shear and strain parameterizations, which indicate highest bottom diffusivities near the critical latitude, independent analysis of current time series from moored instruments shows a thickening of the frictional bottom boundary layer near the critical latitude. Semidiurnal tidal dynamics at the upper continental slope together with the critical latitude effects lead to mixing that might significantly affect the regional heat budget and the circulation in the study area.
Modeling of thermally driven hydrological processes in partially saturated fractured rock
Authors: Tsang Y. W. , Birkholzer J. T. , Mukhopadhyay S.
Published: September 2009

This paper is a review of the research that led to an in‐depth understanding of flow and transport processes under strong heat stimulation in fractured, porous rock. It first describes the anticipated multiple processes that come into play in a partially saturated, fractured porous volcanic tuff geological formation when it is subject to a heat source such as that originating from the decay of radionuclides. The rationale is then given for numerical modeling being a key element in the study of multiple processes that are coupled. The paper outlines how the conceptualization and the numerical modeling of the problem evolved, progressing from the simplified to the more realistic. Examples of numerical models are presented so as to illustrate the advancement and maturation of the research over the last 2 decades. The most recent model applied to in situ field thermal tests is characterized by (1) incorporation of a full set of thermal‐hydrological processes into a numerical simulator, (2) realistic representation of the field test geometry in three dimensions, and (3) use of site‐specific characterization data for model inputs. Model predictions were carried out prior to initiation of data collection, and the model results were compared to diverse sets of measurements. The approach of close integration between modeling and field measurements has yielded a better understanding of how coupled thermal hydrological processes produce redistribution of moisture within the rock, which affects local permeability values and subsequently the flow of liquid and gases. The fluid flow, in turn, will change the temperature field. We end with a note on future research opportunities, specifically those incorporating chemical, mechanical, and microbiological factors into the study of thermal and hydrological processes.
Houston, We Have a Problem: Satellite Altimetry Skews Ocean Depths
Authors: Macnab Ron
Published: September 2009

In the decades after the space program began, several research missions produced global maps of ocean bathymetry. While these maps do an adequate job of portraying generally the seabed on a worldwide or even a regional basis, they fail to convey accurate and detailed pictures of seabed topography over more restricted areas when compared with renditions that can be obtained with multibeam sounding systems.

As more and more laypeople come into contact with seafloor altimeter data through systems such as Google MapsTM, the public erroneously is starting to believe that all of the seafloor has been mapped in fine detail. To prevent this, ocean scientists must take active roles in petitioning those who fund science research that a broad campaign to survey the ocean floor through multibeam sounding systems is as critically needed as studies from space.
Improved confidence in (U‐Th)/He thermochronology using the laser microprobe: An example from a Pleistocene leucogranite, Nanga Parbat, Pakistan
Authors: Boyce J. W. , Hodges K. V. , King D. , Crowley J. L. , Jercinovic M. , Chatterjee N. , Bowring S. A. , Searle M.
Published: September 2009

The newly developed laser microprobe (U‐Th)/He thermochronometer permits, for the first time, the ability to generate precise (U‐Th)/He cooling ages for even very young (<1 Ma) samples with a spatial resolution on the order of tens of micrometers. This makes it possible to test the reproducibility of independent (U‐Th)/He age determinations within individual crystals, further increasing the reliability of the method. As an example, we apply it here to a Pleistocene granite from Nanga Parbat, Pakistan, where previous constraints on the thermal history are consistent with rapid exhumation and cooling. Twenty‐one (U‐Th)/He dates determined on two monazite crystals from a single granite sample yield a mean of 748,000 years with a ∼95% confidence level of ±19,000 years. There is no discernible variation in the distribution of (U‐Th)/He ages in the cores of these crystals and therefore no evidence for the development of substantial diffusive‐loss 4He zoning over 80% of the interior of the monazite crystals during postcrystallization cooling of the granite. Modeling of these data suggests that cooling at a mean rate of ∼300 K/Ma would be necessary to produce the observed ages and the lack of a 4He gradient, which is consistent with preexisting constraints for Nanga Parbat. Increased precision in thermochronology permits more tightly constrained exhumation models, which should aid geologic interpretation.
Relations between proton auroras, intense electric field, and ionospheric electron density depletion
Authors: Fujii R. , Iwata Y. , Oyama S. , Nozawa S. , Ogawa Y.
Published: September 2009

A case study with simultaneous European Incoherent Scatter and optical auroral observations was conducted in order to determine characteristics of the magnetosphere‐ionosphere coupling from the viewpoint of the electrodynamics in the ionosphere. Particularly focused on were the relationships between ionospheric electron density depletion, perpendicular electric fields, and proton auroras. Intense electron density depletion was observed in the E and F regions poleward and in the vicinity of a thin equatorward moving arc. This depletion was associated with an intense, equatorward perpendicular electric field close to ∼80 mV/m and most likely with a downward field‐aligned current (FAC), but it did not accompany detectable proton aurora. Hence the downward FA electric field in the lower magnetosphere associated with this depletion was weak or absent. The motion of the FAC system with the depletion and the arc presumably enabled the downward FAC to obtain enough current carriers as ionospheric electrons were lost by the evacuation process. The evacuation process associated with the downward FAC was, however, efficient enough to establish the depletion. On the other hand, a widely distributed proton aurora observed immediately after the depletion was associated with an intense, equatorward perpendicular electric field close to 90 mV/m, enhanced electron density, and most likely a downward FAC. No electron precipitation was associated with this proton aurora. Thus the electron density enhancement, providing the downward current carriers, had to be caused by the ionization of precipitating protons presumably accelerated by downward field‐aligned electric fields in the lower magnetosphere.
Using data assimilation to identify diffuse recharge mechanisms from chemical and physical data in the unsaturated zone
Authors: Ng Gene‐Hua Crystal , McLaughlin Dennis , Entekhabi Dara , Scanlon Bridget
Published: September 2009

It is difficult to estimate groundwater recharge in semiarid environments, where precipitation and evapotranspiration nearly balance. In such environments, groundwater supplies are sensitive to small changes in the processes that control recharge. Numerical modeling provides the temporal resolution needed to analyze these processes but is highly sensitive to model errors. Natural chloride tracer measurements in the unsaturated zone provide more robust indicators of low recharge rates but yield estimates at coarse time scales that mask most control mechanisms. This study presents a new probabilistic approach for analyzing diffuse recharge in semiarid environments, with an application to study sites in the U.S. southern High Plains. The approach uses data assimilation to combine model predictions and chloride‐based recharge estimates. It has the advantage of providing probability distributions rather than point values for uncertain soil and vegetation properties. These can then be used to quantify recharge uncertainty. Estimates of moisture flux time series indicate that percolation (or potential recharge) at the data sites is episodic and exhibits interannual variability. Most percolation occurs during intense rains when crop roots are not fully developed and there is ample antecedent soil moisture. El Niño events can contribute to interannual variability of recharge if they bring rainy winters that provide wet antecedent conditions for spring precipitation. Data assimilation methods that combine modeling and chloride observations provide the high temporal resolution information needed to identify mechanisms controlling diffuse recharge and offer a way to examine the effects of land use change and climatic variability on groundwater resources.
Cephalometric evaluation of maxillary advancement with an internal distractor in an adult boxer dog
Authors: Stalmans K , Van Erum R , Verdonck A , Nadjmi N , Schepers E , Schoenaers J , Carels C
Published: September 2009

Structured Abstract

Objective – The aim of the study was to evaluate cephalometrically the effects of distraction of the maxilla over a 1‐year period by means of an internal distractor applied in a boxer dog.

Design – Internal distractors were placed bilaterally in the internal cavity of the maxillary sinus of a 2‐year‐old boxer dog after a Le Fort I osteotomy. Distraction was started 5 days after surgery and activations were continued for 14 days at a rate of 1 mm/day. Standardized lateral cephalograms were taken with an external source of 90 kV, 60 mS immediately pre‐surgery, at day 1 after the start of the distraction (dp) and at day 5 dp, day 7 dp, day 10 dp, day 14 dp (end of distraction), at 14 days of consolidation period (cp), at 28 days cp and at 56 days cp (removal of the distractors). One year after the removal of the distractor, a final lateral cephalogram was taken. Cephalometric analysis was performed and superimpositions were used for the evaluation of the sagittal position of the maxilla.

Results – The linear measurements, as well as the superimposition showed evidence for a significantly advanced position of the maxilla, which was stable 1 year after removal of the distractor.

Conclusion – The application of the internal maxillary distractor in a boxer dog resulted in a sagittal advancement of the midface that was still present after 1 year.
Upregulation of immunoreactivity of endothelin‐1 and α‐SMA in PDL microvasculature following acute tooth loading: an immunohistochemical study in the marmoset
Authors: Sims MR , Ashworth JF , Sampson WJ
Published: September 2009

Structured Abstract

Authors – Sims MR, Ashworth JF, Sampson WJ

Objectives – To test the hypothesis that a continuous mechanical tooth load would elevate immunoreactivity of endothelin‐1 (ET‐1) and alpha‐smooth muscle actin (α‐SMA) in the periodontal ligament (PDL) microvasculature.

Design – A randomized control study employing 1.5 h of loading to first molars.

Setting and Sample Population – Orthodontic Research Laboratory, Dental School, Adelaide University. Four young adult, male marmoset monkeys were consecutively anaesthetized and treated.

Experimental Variable – An external telescoping frame applied a jaw closing load (120–200 g) transmitted occlusally, via a rubber pad, to randomly assigned mandibular left or right first molars. Contralateral molars were used as controls.

Outcome Measure – Undemineralized, midsagittal, mandibular molar slices, ∼150 μm thick were immunolabelled with ET‐1 and α‐SMA antibodies and examined in a confocal laser scanning microscope (CLSM) for vascular endothelium and smooth muscle immunolabelling.

Results – Three categories of post‐capillary‐sized venule endothelial cell immunolabelling occurred: endothelium labelled solely with ET‐1; endothelium labelled solely with α‐SMA; endothelium labelled with both ET‐1 and α‐SMA. In endothelial cells, the α‐SMA showed a moderate cytoplasmic distribution with dense peripheral concentration. Loading increased arteriole α‐SMA actin labelling.

Conclusion – Scattered expression of ET‐1 is the default state in primate PDL endothelial cells. Increased antigenicity of endothelial cells to both ET‐1 and α‐SMA, and of arteriolar smooth muscle to α‐SMA, is a response to shear and compression loads.
Angiogenic DC‐SIGN+ cells are present at the attachment sites of epitheliochorial placentae
Authors: Linton Nicola F , Wessels Jocelyn M , Cnossen Sonya A , van den Heuvel Marianne J , Croy B Anne , Tayade Chandrakant
Published: September 2009

Spontaneous early and mid‐gestation fetal losses occur in swine. At both stages, endometrial lymphocytes associated with smaller, paler conceptuses have fewer pro‐angiogenic and more pro‐inflammatory cytokine transcripts compared with robust conceptuses. We hypothesized that similar differences occur in conceptus‐associated dendritic cells (DCs). Using laser capture‐microdissection, dendritic cell‐specific intercellular adhesion molecule‐grabbing non‐integrin (DC‐SIGN)+ cells were isolated from attachment sites of healthy and arresting conceptuses at gestation day (gd)20 and 50. DC‐SIGN+ cells were screened using real‐time PCR for vascular endothelial cell growth factor (Vegf), its receptors, semaphorins (Sema) and plexins (Plxn), and for toll‐like receptor (Tlr) transcripts to address potential activation pathways. Homogenized endometrial and trophoblast biopsies were quantified for type 1/type 2 cytokine transcripts/proteins. DC‐SIGN+ cells from healthy and arresting conceptuses had more Vegf transcripts at early than mid gestation whereas transcripts for Vegfr1 and Vegfr2 were stable. In gd20 arresting site DC‐SIGN+ cells, Neuropilin‐2 transcripts were elevated, whereas at gd50 arresting sites, Plxn‐A2 increased and Sema3A transcripts were lost. Tlr‐1, Tlr‐4 and Tlr‐6 transcript abundance was independent of conceptus health. At gd20, type 1 cytokines were prevalent, whereas at gd50 type 2 cytokines predominated in endometrium and trophoblast. Thus, gestational features, characteristic of haemochorial placentation, are present in species with distinctly different placentation.
The relative importance of stabilizing mechanisms of coexistence
Authors: Yenni Glenda , Xiao Xiao
Published: September 2009

Background/Question/Methods

Stabilizing mechanisms of coexistence, by definition, cause a species to experience greater intraspecific competition than interspecific. This results in negative frequency-dependent growth rates for that species causing a negative relationship between its relative frequency in the community and its growth rate in the next year. The most crucial aspect of this negative relationship for persistence is that it enables a species to increase when rare. This has been empirically demonstrated for pairwise interactions. However, in species-rich communities, the effects of competition are not realistically pairwise. In cases where multiple species are competing for a resource, stabilizing mechanisms become increasingly important to ease the effects of that competition. Thus, for rare species, increasing the strength of stabilization may be essential to their persistence in the community, or their ability to invade. A mathematical model of negative frequency-dependent growth is used to explore how the strength of stabilization affects a species’ ability to persist in a community.

Results/Conclusions

Increasing the steepness of the negative frequency-dependent growth relationship for rare species significantly increases their mean time to extinction in this simulated community. Significantly, the desert rodent community at the Portal LTREB site shows this predicted pattern, in which rare species experience stronger negative frequency-dependant growth relationships than the dominant species. This pattern may be a characteristic of species-rich communities, and thus have implications for the ability of those communities to maintain stable structure despite change (climate change, invasive species, habitat loss).
Phenotypic Plasticity and the Invasiveness of Three Taraxacum Species
Authors: Luo Jing , Cardina John
Published: September 2009

Background/Question/Methods

Many factors have been found to be associated with the success of invasive species. Phenotypic plasticity, the ability of a plant genotype to respond to different environmental conditions by producing different phenotypes, is thought to play an important role plant invasions. In three major experiments, I tested the hypothesis that the invasive Taraxacum officinale (common dandelion) and its non-invasive congener T. laevigatum will exhibit different phenotypic plasticity in germination, growth, and reproduction. I also proposed that their responses to various environments could be used to assess the invasive behavior of a potential crop species: T. kok-saghyz.

Results/Conclusions

The results revealed complicated responses of the three species in various environments. The invasive T. officinale showed higher germination in high alternating temperature, and accumulated more biomass than the non-invasive T. laevigatum in favorable greenhouse conditions. Surprisingly, T. laevigatum germinated better than T. officinale in other stressful environments (dark, low water potential, long aging period), and also exhibited higher fecundity in favorable greenhouse conditions. In field experiments, however, the performance of T. officinale was overwhelmingly better than T. laevigatum, which suffered very high mortality and failed to survive for more than two growing seasons. These results suggest that T. officinale might benefit from its ability to grow, reproduce, and survive in various environments, while T. laevigatum relies on seed reproduction to maintain its population. With the exception of germination, the responses of T. kok-saghyz were more like T. officinale than T. laevigatum, which suggested that this species has some potential to behave as a weed.
Ionization of Strong Electrolytes. V. Proton Magnetic Resonance in Sulfuric Acid
Authors: Hood G. C. , Reilly C. A.
Published: September 2009

The proton magnetic resonance shifts in solutions of sulfuric acid have been measured and degrees of dissociation calculated. The results are consistent with information derived from the intensities of Raman lines.
A high-precision apparatus for the characterization of thermal interface materials
Authors: Kempers R. , Kolodner P. , Lyons A. , Robinson A. J.
Published: September 2009

An apparatus has been designed and constructed to characterize thermal interface materials with unprecedented precision and sensitivity. The design of the apparatus is based upon a popular implementation of ASTM D5470 where well-characterized meter bars are used to extrapolate surface temperatures and measure heat flux through the sample under test. Measurements of thermal resistance, effective thermal conductivity, and electrical resistance can be made simultaneously as functions of pressure or sample thickness. This apparatus is unique in that it takes advantage of small, well-calibrated thermistors for precise temperature measurements (±0.001 K) and incorporates simultaneous measurement of electrical resistance of the sample. By employing precision thermometry, low heater powers and minimal temperature gradients are maintained through the meter bars, thereby reducing uncertainties due to heat leakage and changes in meter-bar thermal conductivity. Careful implementation of instrumentation to measure thickness and force also contributes to a low overall uncertainty. Finally, a robust error analysis provides uncertainties for all measured and calculated quantities. Baseline tests were performed to demonstrate the sensitivity and precision of the apparatus by measuring the contact resistance of the meter bars in contact with each other as representative low specific thermal resistance cases. A minimum specific thermal resistance of 4.68×10−6 m2 K/W was measured with an uncertainty of 2.7% using a heat transfer rate of 16.8 W. Additionally, example measurements performed on a commercially available graphite thermal interface material demonstrate the relationship between thermal and electrical contact resistance. These measurements further demonstrate repeatability in measured effective thermal conductivity of approximately 1%.
Resonator spectrometer for precise broadband investigations of atmospheric absorption in discrete lines and water vapor related continuum in millimeter wave range
Authors: Tretyakov M. Yu. , Krupnov A. F. , Koshelev M. A. , Makarov D. S. , Serov E. A. , Parshin V. V.
Published: September 2009

The instrument and methods for measuring spectral parameters of discrete atmospheric lines and water-related continuum absorption in the millimeter wave range are described. The instrument is based on measurements of the Fabry–Pérot resonance response width using fast phase continuous scanning of the frequency-synthesized radiation. The instrument allows measurement of gas absorptions at the cavity eigenfrequencies ranging from 45 to 370 GHz with the highest to date absorption variation sensitivity of 4×10−9 cm−1. The use of a module of two rigidly bounded maximum identical resonators differing in length by exactly a factor of two allows accurate separation of the studied gas absorption and spectrometer baseline, in particular, the absorption by water adsorbed on the resonator elements. The module is placed in a chamber with temperature controlled between −30 and +60 °C, which permits investigation of temperature dependence of absorption. It is shown that systematic measurement error of discrete atmospheric line parameters does not exceed the statistical one and the achieved accuracy satisfies modern demands for the atmospheric remote sensing data retrieval. Potential systematic error arising from the neglect of the effect of water adsorption on mirror surfaces is discussed. Examples of studies of water and oxygen spectral line parameters as well as continuum absorption in wet nitrogen are given.
On measuring the strength of metals at ultrahigh strain rates
Authors: Vogler T. J.
Published: September 2009

The strain rate sensitivity of materials is normally measured through a combination of quasistatic, Hopkinson bar, and pressure-shear experiments. Recent advances in uniaxial strain ramp loading provide a new means to reach strain rates significantly higher than achievable in pressure-shear experiments. One way to determine strength in ramp loading is by comparing the uniaxial stress-strain response to an appropriate pressure-density response obtained from an equation of state for the material. Using this approach, strengths for aluminum are obtained for strain rates of 105–108 s−1. Two issues arise in this calculation: heating due to plastic work and the effect of the superimposed hydrostatic stress on the strength. Heating due to plastic work is calculated and accounted for within the context of the equation of state for the material in a straightforward manner, but neglecting this heating can lead to significant errors in the calculated strength at higher compression levels. A simple scaling of strength with the pressure-dependent shear modulus is utilized to estimate the strength at zero pressure for ramp loading and pressure-shear experiments. When examined in this manner, the strain rate dependence of aluminum is found to be less than previously reported, with little increase in strength below strain rates of about 107s−1. The effects on ramp loading strength measurements of heating due to plastic work and of hydrostatic pressure are also examined for copper and tantalum using simple equation of state and strength models. The effect of plastic heating is similar for the three materials for a given strain level but quite different for a constant stress, with aluminum showing greater effects than the other materials. The effect of hydrostatic pressure in ramp loading experiments is similar for all three materials, but the effect is likely to be much greater in pressure-shear experiments for aluminum than the other materials.