Rare-gas optics-free stable extreme-ultraviolet photon spectrometer for solar system studies

We have developed a prototype spectrometer for space applications that require long-term stable EUV photon flux measurements. In this recently developed spectrometer, the energy spectrum of the incoming photons is transformed directly into an electron energy spectrum by taking advantage of the photoelectric effect in one of several rare gases at low pressures. Using an electron energy spectrometer operating at a few electron volts, and followed by an electron multiplying detector, pulses due to individual electrons are counted. The overall efficiency of this process is essentially independent of gain drifts in the signal path, and the secular degradation of optical components that is often a problem in other techniques is avoided

Granivory in the Chihuahuan Desert: interactions within and between trophic levels

Journal ArticleWe investigated the effects of Chihuahuan Desert granivores on three seasonal classes of plant resource species, the effects of these resource classes on one another, and the ways in which interactions through plant resources affect the abundances of seed consumers. At our study site, three seasonally distinct classes of annual plants produce the seeds used by ants and rodents, the two major taxa of resident granivores. Winter annuals and summer annuals have temporally nonoverlapping growth periods. However, one numerically prominent annual, Eriogonum abertianum, germinates with winter annuals, reproduces with summer annuals, and may link the population dynamics of plants in the two groups. Experiments showed that high densities of winter annuals inhibit populations of E. abertianum and that populations of this species can strongly suppress those of summer annuals. Densities of all three classes of annuals are regulated by the combined effects of competition and seed predation. In E. abertianum, interspecific and intraspecific competition appeared to predominate in alternate years and to produce 2-yr abundance cycles, accentuated in magnitude where ants, the major seed predators, had been removed. The period of these cycles appeared to lengthen where rodent removal intesified the effects of interspecific competition. Granivore removal and seed addition experiments showed that competition also helps to regulate some granivore populations. Although rodents reduced ant resources through their effects on seeds of both summer annuals and winter annuals, ants were competitors of rodents only for seeds produced during the weaker winter resource peak. Seeds of E. abertianum were used almost exclusively by ants. Rodents facilitated this plant species indirectly by reducing densities of other winter annuals. Ants and rodents were affected differently by one another's removal. After an initial time delay, workers of Pheidole xerophila increased in numbers and/or activity on rodent removal plots, but colony densities of a second ant species, Pogonomyrmex desertorum, simultaneously declined. Rodents did not compensate measurably in abundance, biomass, or reproductive activity where ants had been eliminated. The explanation for these responses is complex and includes such factors as: (1) seasonality in the production of seed resources and in their use by the two taxa; (2) specialization by ants and rodents on different density distributions of seeds; (3) "diffuse compensation," or compensation spread over many species populations; and (4) indirect interaction pathways, mediated through competing resource classes. In general, our experiments show that, despite the climatic variability and unpredictability of desert environments, populations respond to the steady deterministic processes of competition and predation. Nevertheless, comparison of the results of similar experimental studies in the Sonoran and Chihuahuan Deserts demonstrates how climate and seasonality can alter the structure and intensity of interactions in ecosystems

Granivory in the Chihuahuan desert: interactions within and between trophic levels

Journal ArticleWe investigated the effects of Chihuahuan Desert granivores on three seasonal classes of plant resource species, the effects of these resource classes on one another, and the ways in which interactions through plant resources affect the abundances of seed consumers. At our study site, three seasonally distinct classes of annual plants produce the seeds used by ants and rodents, the two major taxa of resident granivores. Winter annuals and summer annuals have temporally nonoverlapping growth periods. However, one numerically prominent annual, Eriogonum abertianum, germinates with winter annuals, reproduces with summer annuals, and may link the population dynamics of plants in the two groups. Experiments showed that high densities of winter annuals inhibit populations of E. abertianum and that populations of this species can strongly suppress those of summer annuals. Densities of all three classes of annuals are regulated by the combined effects of competition and seed predation. In E. abertianum, interspecific and intraspecific competition appeared to predominate in alternate years and to produce 2-yr abundance cycles, accentuated in magnitude where ants, the major seed predators, had been removed. The period of these cycles appeared to lengthen where rodent removal intesified the effects of interspecific competition. Granivore removal and seed addition experiments showed that competition also helps to regulate some granivore populations. Although rodents reduced ant resources through their effects on seeds of both summer annuals and winter annuals, ants were competitors of rodents only for seeds produced during the weaker winter resource peak. Seeds of E. abertianum were used almost exclusively by ants. Rodents facilitated this plant species indirectly by reducing densities of other winter annuals. Ants and rodents were affected differently by one another's removal. After an initial time delay, workers of Pheidole xerophila increased in numbers and/or activity on rodent removal plots, but colony densities of a second ant species, Pogonomyrmex desertorum, simultaneously declined. Rodents did not compensate measurably in abundance, biomass, or reproductive activity where ants had been eliminated. The explanation for these responses is complex and includes such factors as: (1) seasonality in the production of seed resources and in their use by the two taxa; (2) specialization by ants and rodents on different density distributions of seeds; (3) "diffuse compensation," or compensation spread over many species populations; and (4) indirect interaction pathways, mediated through competing resource classes. In general, our experiments show that, despite the climatic variability and unpredictability of desert environments, populations respond to the steady deterministic processes of competition and redation. Nevertheless, comparison of the results of similar experimental studies in the Sonoran and Chihuahuan Deserts demonstrates how climate and seasonality can alter the structure and intensity of interactions in ecosystems

Trace Metals Concentration Determination In Domestic Water From Keana Mine Area Of Nasarawa State, Nigeria

Water samples from Keana mine area of Nasarawa State were analysed for some trace metals concentration, using the Inductively Coupled Plasma Optical Emission Spectrometry technique (ICP OES).  The results of the analysis were compared with the standards of the World Health Organisation (WHO) and the European (EU) for domestic water.A total of 12 water samples were drawn from sources across the study area, comprising of 4 well samples, 4 stream samples, and 4 borehole samples. Analyses were carried out for a total of seven (7) elements which included; As, Cd, Cr, Sr, Pb, Th and Zn. Arsenic (As) was detected in all the samples at a mean concentration of.............

Self-Organization in Multimode Microwave Phonon Laser (Phaser): Experimental Observation of Spin-Phonon Cooperative Motions

An unusual nonlinear resonance was experimentally observed in a ruby phonon laser (phaser) operating at 9 GHz with an electromagnetic pumping at 23 GHz. The resonance is manifested by very slow cooperative self-detunings in the microwave spectra of stimulated phonon emission when pumping is modulated at a superlow frequency (less than 10 Hz). During the self-detuning cycle new and new narrow phonon modes are sequentially ``fired'' on one side of the spectrum and approximately the same number of modes are ``extinguished'' on the other side, up to a complete generation breakdown in a certain final portion of the frequency axis. This is usually followed by a short-time refractority, after which the generation is fired again in the opposite (starting) portion of the frequency axis. The entire process of such cooperative spectral motions is repeated with high degree of regularity. The self-detuning period strongly depends on difference between the modulation frequency and the resonance frequency. This period is incommensurable with period of modulation. It increases to very large values (more than 100 s) when pointed difference is less than 0.05 Hz. The revealed phenomenon is a kind of global spin-phonon self- organization. All microwave modes of phonon laser oscillate with the same period, but with different, strongly determined phase shifts - as in optical lasers with antiphase motions.Comment: LaTeX2e file (REVTeX4), 5 pages, 5 Postscript figures. Extended and revised version of journal publication. More convenient terminology is used. Many new bibliographic references are added, including main early theoretical and experimental papers on microwave phonon lasers (in English and in Russian

Signal Processing

Contains reports on three research projects.Joint Services Electronics Programs (U.S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300U. S. Coast Guard (Contract DOT-CG -13446-A)M.I.T. Lincoln Laboratory Purchase Order CC-57

T2 lesion location really matters: a 10 year follow-up study in primary progressive multiple sclerosis

Objectives: Prediction of long term clinical outcome in patients with primary progressive multiple sclerosis (PPMS) using imaging has important clinical implications, but remains challenging. We aimed to determine whether spatial location of T2 and T1 brain lesions predicts clinical progression during a 10-year follow-up in PPMS. Methods: Lesion probability maps of the T2 and T1 brain lesions were generated using the baseline scans of 80 patients with PPMS who were clinically assessed at baseline and then after 1, 2, 5 and 10 years. For each patient, the time (in years) taken before bilateral support was required to walk (time to event (TTE)) was used as a measure of progression rate. The probability of each voxel being ‘lesional’ was correlated with TTE, adjusting for age, gender, disease duration, centre and spinal cord cross sectional area, using a multiple linear regression model. To identify the best, independent predictor of progression, a Cox regression model was used. Results: A significant correlation between a shorter TTE and a higher probability of a voxel being lesional on T2 scans was found in the bilateral corticospinal tract and superior longitudinal fasciculus, and in the right inferior fronto-occipital fasciculus (p<0.05). The best predictor of progression rate was the T2 lesion load measured along the right inferior fronto-occipital fasciculus (p=0.016, hazard ratio 1.00652, 95% CI 1.00121 to 1.01186). Conclusion: Our results suggest that the location of T2 brain lesions in the motor and associative tracts is an important contributor to the progression of disability in PPMS, and is independent of spinal cord involvement

GRANIVORY IN THE CHIHUAHUAN DESERT: INTERACTIONS WITHIN AND BETWEEN TROPHIC LEVELS1

R. S. Inouye2 D ep a rtm en t o f E c o lo g y a n d E v o lu tio n a ry B iology, U n iversity o f A rizo n a , Tucson, A rizo n a 8 5 7 2 1 USA A bstract. We investigated the effects o f Chihuahuan Desert granivores on three seasonal classes of plant resource species, the effects o f these resource classes on one another, and the ways in which interactions through plant resources affect the abundances o f seed consumers. At our study site, three seasonally distinct classes of annual plants produce the seeds used by ants and rodents, the two major taxa of resident granivores. W inter annuals and sum m er annuals have temporally nonoverlapping growth periods. However, one numerically prom inent annual, E rio g o n u m ab ertia n u m , germinates with winter annuals, reproduces with sum mer annuals, and may link the population dynamics of plants in the two groups. Experiments showed that high densities of winter annuals inhibit populations of E. a b ertia n u m and that populations of this species can strongly suppress those of sum m er annuals. Densities o f all three classes o f annuals are regulated by the combined effects o f competition and seed predation. In E . abertian u m , interspecific and intraspecific competition appeared to predominate in alternate years and to produce 2-yr abundance cycles, accentuated in magnitude where ants, the major seed predators, had been removed. The period o f these cycles appeared to lengthen where rodent removal intesified the effects o f interspecific competition. Granivore removal and seed addition experiments showed that competition also helps to regulate some granivore populations. Although rodents reduced ant resources through their effects on seeds of both sum mer annuals and winter annuals, ants were competitors of rodents only for seeds produced during the weaker winter resource peak. Seeds of E. a b ertia n u m were used alm ost exclusively by ants. Rodents facilitated this plant species indirectly by reducing densities of other winter annuals. Ants and rodents were affected differently by one another&apos;s removal. After an initial time delay, workers of P h eidole x ero p h ila increased in numbers and/or activity on rodent removal plots, but colony densities of a second ant species, P o g o n o m y rm e x desertoru m , simultaneously declined. Rodents did not compensate measurably in abundance, biomass, or reproductive activity where ants had been eliminated. The explanation for these responses is complex and includes such factors as: (1) seasonality in the production o f seed resources and in their use by the two taxa; (2) specialization by ants and rodents on different density distributions of seeds; (3) &quot;diffuse compensation,&quot; or compensation spread over many species populations; and (4) indirect interaction pathways, mediated through competing resource classes. In general, our experiments show that, despite the climatic variability and unpredictability of desert environments, populations respond to the steady deterministic processes o f competition and predation. Nevertheless, comparison of the results of similar experimental studies in the Sonoran and Chihuahuan Deserts demonstrates how climate and seasonality can alter the structure and intensity o f interactions in ecosystems. K e y words: a n n u a l p la n t; ant; co m p etitio n ; c o m m u n ity ; desert; eco system stru ctu re; experim en t; granivore; in direct in teraction ; rodent; p o p u la tio n cycles; se ed predation

Ordering intermetallic alloys by ion irradiation: a way to tailor magnetic media

Combining He ion irradiation and thermal mobility below 600K, we both trigger and control the transformation from chemical disorder to order in thin films of an intermetallic ferromagnet (FePd). Kinetic Monte Carlo simulations show how the initial directional short range order determines order propagation. Magnetic ordering perpendicular to the film plane was achieved, promoting the initially weak magnetic anisotropy to the highest values known for FePd films. This post-growth treatment should find applications in ultrahigh density magnetic recording.Comment: 7 pages, 3 Figure

Racial Disparities in Caesarean Delivery Among Nulliparous Women that Delivered at Term: Cross-Sectional Decomposition Analysis of Nebraska Birth Records

Background: Access to medically indicated caesarean sections is an essential strategy for reducing maternal and infant mortality rates worldwide. However, overuse of medically unnecessary caesarean sections is associated with excess maternal-child morbidity. Previous studies suggest higher rates of caesarean section among women who identify as racial/ethnic minorities. Significance of Problem: Despite national efforts to prioritize the reduction of medically unnecessary caesarean sections, caesareans rates in the United States have remained stable over the last decade. Women who identify as racial or ethnic minorities experience disproportionally higher rates of caesarean, even when controlling for demographic, behavioral, medical, and institutional level factors. However, detailed analysis of factors contributing to racial/ethnic disparities in caesarean section rates remains largely unexplored. Identifying these factors and assessing their relative importance is critical for the development of interventions specifically tailored to reduce racial and ethnic disparities in caesarean use. Question: The objective of this study was to understand underlying social and demographic factors that contribute to differences in caesarean rates across racial and ethnic groups. Experimental Design: Data was collected from 2005-2014 Nebraska birth records on singleton births occurring on or after 37 weeks gestation (n=87,908). Risk ratios (RR) and 95% confidence intervals (CI) for caesarean were calculated for different racial and ethnic categories. Fairlie decomposition technique was utilized to quantify the contribution of individual variables to the observed differences in caesarean. Results: In the adjusted analysis, relative to non-Hispanic (NH) White race, both Asian-NH (RR 1.21, 95% CI 1.14, 1.28) and Black-NH races (RR 1.13, 95% CI 1.08, 1.19) were associated with a significantly higher risk for caesarean. The decomposition analysis showed that among the variables assessed, maternal age, education, and pre-pregnancy BMI contributed the most to the observed differences in caesarean rates across racial/ethnic groups. Conclusion: This analysis quantified the effect of social and demographic factors on racial differences in caesarean delivery, which may guide public health interventions aimed towards reducing racial disparities in caesarean rates. Interventions targeted towards modifying maternal characteristics, such as reducing pre-pregnancy BMI or increasing maternal education, may narrow the gap in caesarean rates across racial and ethnic groups. Future studies should determine the contribution of physician characteristics, hospital characteristics, and structural determinants of health towards racial disparities in caesarean rates.https://digitalcommons.unmc.edu/chri_forum/1064/thumbnail.jp