A multigrid continuation method for elliptic problems with folds

We introduce a new multigrid continuation method for computing solutions of nonlinear elliptic eigenvalue problems which contain limit points (also called turning points or folds). Our method combines the frozen tau technique of Brandt with pseudo-arc length continuation and correction of the parameter on the coarsest grid. This produces considerable storage savings over direct continuation methods,as well as better initial coarse grid approximations, and avoids complicated algorithms for determining the parameter on finer grids. We provide numerical results for second, fourth and sixth order approximations to the two-parameter, two-dimensional stationary reaction-diffusion problem: Δu+λ exp(u/(1+au)) = 0. For the higher order interpolations we use bicubic and biquintic splines. The convergence rate is observed to be independent of the occurrence of limit points

Opportunity in dange : Manstein's East Front strategy from 19 Nov 1942 to 18 Mar 1943

In the 1990s the United States Armed Forces will be asked by its leaders to do more with less. This represents a significant turn from the policies of the last decade. During World War Two the German Army operated effectively under similar policy constraints. There are many lessons in strategic planning that can be learned from Field Marshal Erich von Manstein's operations during the Winter of 1942-43. He was able to grasp tremendous opportunity amid extreme strategic danger. He decisively changed the strategic situation on the Eastern Front over a four month period. This thesis addresses the following questions. What factors enabled him to operate so effectively? What hindered him? What decisions did he make, when and why? How might leaders today make similar decisions under similar circumstances and be as successful? The answers to these questions will be of great value to the United States Armed Forces as they restructure themselves for the 1990s.http://archive.org/details/opportunityindan00bolsLieutenant, United States NavyApproved for public release; distribution is unlimited

Effect of calf stimulation on milk ejection in reindeer (Rangifer tarandus)

The objective of this study was to establish methods for stimulating the milk ejection in reindeer kept for milking purpose. Calves were used to stimulate milk does’ let down. In experiment 1, five does were allowed olfactory, acoustic and visual contact with their calves during milking, whereas four does were milked in isolation. The treatment of the groups was alternated every day during the eight days experiment. Olfactory, acoustic and visual contact with the calf did not influence the doe’s milk yield. The milk yield varied significantly between individual females within treatment (P < 0.01). In experiment 2, the calves were allowed to suckle their mother for a short period (two seconds) prior to milking being initiated. The same alternate design as in experiment 1 with groups consisting of three and two animals respectively was used, and the experiment lasted four days. The pre-suckling stimulation significantly increased the milk ejection measured as milk yield (P < 0.05), and the residual milk after the treatment was negectible. Moreover, the milk ejection varied between individual females within treatment (P < 0.05). We conclude that it is possible to achieve a complete milk removal by machine milking after the does have been pre-stimulated by suckling of calves. Olfactory, acoustic and visual contact with calves during milking failed to influence the milk ejection in this study. However, the results have to be interpreted with caution due to limited sample size.Abstract in Norwegian / Sammendrag: Formålet med dette forsøket var å prøve ut ulike metoder for å stimulere nedgivninga av melk hos rein. Kalvene ble tatt i bruk for å stimulere nedgivninga. I forsøk 1 hadde simla lyd-, lukt og synskontakt med kalven mens melkingen pågikk. Vi benyttet et ”switch back design” der fem simler hadde kontakt med kalven under melkingen og fire ble melket uten kontakt. Behandlingen ble byttet om annenhver dag i de åtte dagene forsøket varte. Lyd-, lukt og synskontakt med kalven under melking hadde ingen innvirkning på melkemengden ved maskinmelking. Det var imidlertid individuell variasjon i hvor mye melk man oppnådde hos simlene (P < 0.01). I forsøk 2 lot vi kalvene suge simlene en kort stund før simlene ble melket. Kalven ble sluppet inn til simla og sugingen ble avbrutt etter to sekunder. Deretter ble simla ført inn for maskinmelking. Forsøket varte i fire dager og vi benyttet samme ”switch back design” som i forsøk 1, med grupper bestående av henholdsvis to og tre dyr. Stimuleringa med suging hadde en signifikant innvirkning på nedgivninga. (P < 0.05), og mengden gjenværende melk var minimal. Dessuten var det en signifikant individuell variasjon i melkemengden innen behandlingen (P < 0.05). Vi konkluderer med at det er mulig å oppnå en fullstendig tømming av juret ved maskinmelking dersom simlene først er blitt stimulert med suging av kalven. Lyd-, lukt- og synskontakt med kalven under melking hadde ingen innvirkning på nedgivninga av melk i dette forsøket. Resultatene må imidlertid tolkes med varsomhet siden det statistiske utvalget er begrenset

Pre-processing and differential expression analysis of Agilent microRNA arrays using the AgiMicroRna Bioconductor library

<p>Abstract</p> <p>Background</p> <p>The main research tool for identifying microRNAs involved in specific cellular processes is gene expression profiling using microarray technology. Agilent is one of the major producers of microRNA arrays, and microarray data are commonly analyzed by using R and the functions and packages collected in the Bioconductor project. However, an analytical package that integrates the specific characteristics of microRNA Agilent arrays has been lacking.</p> <p>Results</p> <p>This report presents the new bioinformatic tool <it>AgiMicroRNA </it>for the pre-processing and differential expression analysis of Agilent microRNA array data. The software is implemented in the open-source statistical scripting language R and is integrated in the Bioconductor project (<url>http://www.bioconductor.org</url>) under the GPL license. For the pre-processing of the microRNA signal, <it>AgiMicroRNA </it>incorporates the <it>robust multiarray average algorithm</it>, a method that produces a summary measure of the microRNA expression using a linear model that takes into account the probe affinity effect. To obtain a normalized microRNA signal useful for the statistical analysis, <it>AgiMicroRna </it>offers the possibility of employing either the processed signal estimated by the <it>robust multiarray average algorithm </it>or the processed signal produced by the Agilent image analysis software. The <it>AgiMicroRNA </it>package also incorporates different graphical utilities to assess the quality of the data. <it>AgiMicroRna </it>uses the linear model features implemented in the <it>limma </it>package to assess the differential expression between different experimental conditions and provides links to the <it>miRBase </it>for those microRNAs that have been declared as significant in the statistical analysis.</p> <p>Conclusions</p> <p><it>AgiMicroRna </it>is a rational collection of Bioconductor functions that have been wrapped into specific functions in order to ease and systematize the pre-processing and statistical analysis of Agilent microRNA data. The development of this package contributes to the Bioconductor project filling the gap in microRNA array data analysis.</p

Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks

The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth\u27s climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO2 uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO2 uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycle–climate models

The relationships between use of alcohol, tobacco and coffee in adolescence and mood disorders in adulthood

Introduction Alcohol, tobacco and coffee are commonly used substances and use in adolescence has previously been linked to mood disorders. However, few large prospective studies have investigated adolescent use in relation to mental health outcomes in adulthood. The main aim of this study was to examine the prospective associations between alcohol use, cigarette smoking and coffee consumption at age 16 and subsequent mood disorders up to 33 years of age. Methods Data from The Northern Finland Birth Cohort 1986 Study were used and a total of 7660 participants (49.9% male) were included. Associations between alcohol use, cigarette smoking and coffee consumption at age 16 and later diagnoses of major depression and bipolar disorder were examined using multinomial logistic regression analyses. Results Mean number of cigarettes/day (OR, 1.23 [95% CI 1.01-1.50]) and mean volume of alcohol consumption (OR, 1.22 [95% CI 1.01-1.47]), but not frequency of excessive drinking, in adolescence were associated with increased risk for subsequent bipolar disorder after adjustment for sex, parental psychiatric disorders, family structure, illicit substance use, and emotional and behavioral problems at age 16. An association between cigarette smoking and major depression attenuated to statistically non-significant when adjusted for emotional and behavioral problems. No associations were observed between adolescent coffee consumption and subsequent mood disorders. Conclusions This is the first study to report an association of adolescent cigarette smoking and subsequent bipolar disorder diagnosis providing grounds for further research and pointing to a place for preventive measures among adolescents.Peer reviewe