Discovery of Single Top Quark Production

The first observation of electroweak single top quark production was recently reported by the the D0 and CDF collaborations based on 2.3 and 3.2 fb-1 of ppbar collision data collected at \sqrt{s}=1.96 TeV from the Fermilab Tevatron collider. Several multivariate techniques are used to separate the single top signal from backgrounds, and both collaborations present measurements of the single top cross section and the CKM matrix element |Vtb|.Comment: 4 pages, proceedings for Moriond QCD and High Energy Interactions, March 14th - March 21st 200

Early symptomatic syndromes eliciting neurodevelopmental clinical examinations

No abstract available

Neurobiological abnormalities in the first few years of life in individuals later diagnosed with Autistic Spectrum Disorder : A review of recent data

Peer reviewedPublisher PD

Overwintering strategies in polar copepods : Physiological mechanisms and buoyancy regulation by ammonium

Copepods play a vital role in marine pelagic food webs. They channel energy from primary production to higher trophic levels and, via the biological carbon pump, substantially affect biogeochemical cycles and carbon fluxes. The distinct seasonality of primary production is the most important factor influencing life-cycle adaptions of herbivorous copepods in polar ecosystems. Ontogenetic seasonal vertical migration (OVM) with a resting stage (diapause) at great depth is known as an adaption to escape food scarcity during winter. Diapause is characterised by reduced metabolic rates and the cessation of feeding. Therefore, diapausing copepods are presumably neutrally buoyant to avoid a depletion of their restricted recources by swimming movements. However, no experimental observations or density determinations had been conducted for Antarctic copepods so far and the mechanisms triggering the on- and offset of OVM and diapause, and regulating buoyancy, were still far from understood. Within the present study, novel hypotheses about the controlling factors for dormancy and OVM were established. The accumulation of ammonium (NH4 ) and the replacement of ions with a higher density is a known buoyancy regulation mechanism in several marine invertebrates. To keep ammonium in the less toxic ionised form, a low pH is required. Knowing that acidic pH conditions are a relevant factor inducing metabolic reduction, a low haemolymph pH might not only be a precondition for ammonium accumulation, but in addition trigger dormancy in copepods. Buoyancy observations of anaesthetised individuals revealed that diapausing Calanoides acutus was neutrally buoyant during austral winter, whereas actively overwintering Calanus propinquus was negatively buoyant. Diapausing and non-diapausing species differed sigificantly in their extracellular cation composition. In actively overwintering species, the cation composition of the haemolymph was similar to that of seawater. In diapausing copepods, severly elevated concentrations of up to 530 mmol L-1 NH4 and reduced contributions of the remaining cations Na , Ca2 and Mg2 were found. Moreover, elevated ammonium levels were accompanied by acidic conditions of pHâ ¤6. The replacement of cations with a higher molecular weight against low density ammonium decreases the overall density of the diapausing copepod and supports neutral buoyancy, while staying isoosmotic with the surrounding seawater. The present study contributes to a better understanding of the regulation mechanisms of dominant copepods' life cycles, in particular of the triggering and controlling factors of vertical migration and diapause. Since polar oceans are most strongly affected by climate change and global warming, knowledge about physiological and metabolic adaptations of polar species is of profound relevance for understanding and predicting effects on the whole polar marine ecosystem

The role of nitric oxide in the gastrointestinal tract

Nitric oxide (NO) is an important second messenger involved in the regulation of a multitude of mechanisms in the body, such as neurotransmission, smooth muscle contractility, host defense and immune regulation. Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic disorders affecting the gastrointestinal (GI) tract with unknown etiology. These diseases are characterized by increased NO levels in the gut lumen, aberrant leukocyte recruitment to the inflamed tissue and changed motility pattern of the intestines. This thesis aimed to investigate NO’s involvement in inflammatory reactions as well as its regulatory role on motility in the GI tract by studying NO-related gene expression in IBD, α2 integrin antibody treatment in comparison to conventional IBD drugs in experimental colitis, neuropeptide S (NPS) effects on motility, contractility and inflammation, as well as NO’s regulation of the migrating motor complex (MMC) in relation to muscarinic and 5-HT3 receptor blockade. Cluster analysis of NO-related gene expression in CD and UC revealed common pathophysiological processes, with hypoxia-inducible factor 1 (HIF-1) as a central regulator of inflammation, angiogenesis and tissue fibrosis. Moreover, interaction analysis pinpointed the association of upregulated expression of IL-8 and ICAM-1 in both diseases, highlighting an exaggerated leukocyte infiltration in the pathophysiology of CD and UC. In comparison to conventional IBD drugs, treatment with a function-blocking anti-α2 antibody by rectal administration showed alleviation of signs of colitis, such as reduced body weight loss, rectal bleeding, inflammation score and inflammatory biomarker expression including inducible NO synthase (iNOS). Although treatment with methotrexate also showed several signs of ameliorated colitis, these effects were not accompanied by a broad reduction in inflammatory marker expression. This study provides evidence for therapeutic use of integrin α2β1 as a novel drug target for treatment of IBD. Infusion with NPS prolonged the MMC cycle length and the phase III duration in upper small intestine. Contractility studies on excised human muscle strips revealed a dampening of the amplitude, with NPS acting directly on small intestine circular muscle, while this effect seems mediated by prejunctional receptors in colon. These effects of NPS on motility and contractility are in agreement with the changes seen during inflammatory reactions in the intestine. Moreover, NPS induced the expression of inflammatory markers iNOS, IL-1β and CXCL1, further supporting a role of NPS in NO-dependent induction of inflammation in the GI tract. Studies with the NOS inhibitor L-NMMA suggested marked effects of NO on motility. L-NMMA, shown to inhibit NO, initiated phase III MMC activity, while additional muscarinic and 5-HT3 receptor blockades revealed that the transition from phase I to phase II activity seem regulated as a balance between inhibitory nitrergic and excitatory cholinergic and serotonergic pathways. These results demonstrate increased iNOS expression during inflammatory reactions in the GI tract, with the resulting increase of NO as a pathophysiological inhibitor of motility seen in inflammatory disorders of the GI tract

Oppimisen kohdentaminen easymmetrisen harvuuden avulla

Useat viime vuosina kerätyt havaintoaineistot koostuvat mittauksista hyvin pienestä määrästä näytteitä. Tällaisten aineistojen mallintaminen on haasteellista, koska mallit helposti ylisovittuvat aineistoon. Ongelmaan on kehitetty useita lähestymistapoja. Pääasiallisen mallinnustehtävän rinnalle voidaan ottaa muita mallinnustehtäviä, joissa käytettävät mallit kytketään pääasiallisen tehtävän malliin. Näin mallien yhteisten osien oppimiseen on käytettävissä enemmän aineistoa, mikä parantaa tulosten yleistymistä uusiin aineistoihin. Tätä lähestymistapaa kutsutaan monitehtäväoppimiseksi. Käytettävää mallia voidaan myös rajoittaa lisäämällä siihen oletuksia, jotka rajoittavat mallin sovittumista aineistoon ja siten vähentävät ylisovittumista. Tyypilliset monitehtäväoppimista hyödyntävät mallit painottavat kaikkia oppimistehtäviä yhtä voimakkaasti, vaikka yksi oppimistehtävä on yleensä muita tärkeämpi. Tämä diplomityö on esitutkimus uudesta lähestymistavasta, joka pyrkii monitehtäväoppimisasetelmassa parantamaan yleistyvyyttä yhdessä oppimistehtävässä eri mallien sovittumiskykyä rajoittavien oletusten avulla. Valitussa oppimistehtävässä mallin sovittumista aineistoon rajoitetaan muita oppimistehtäviä enemmän mallin harvuutta lisäämällä, jotta tehtävälle opittu malli yleistyisi paremmin. Uutta lähestymistapaa tutkitaan rajaamalla tutkimuskysymys suosittuihin LDAmalleihin, joissa hyödynnetään bayesilaisia epäparametrisia priorijakaumia. Epäsymmetrisen harvuuden vaikutuksia tutkitaan tämän malliperheen avulla. Tuloksissa on havaittavissa hienovaraisia parannuksia yleistyvyyteen. Tulokset uudella mallilla ovat kilpailukykyisiä tämän hetkisten johtavien menetelmien tulosten kanssa.Modern data sets often suffer from the problem of having measurements from very few samples. The small sample size makes modeling such data sets very difficult, as models easily overfit to the data. Many approaches to alleviate the problem have been taken. One such approach is multi-task learning, a subfield of statistical machine learning, in which multiple data sets are modeled simultaneously. More generally, multiple learning tasks may be learnt simultaneously to achieve better performance in each. Another approach to the problem of having too few samples is to prevent over fitting by constraining the model by making suitable assumptions. Traditional multi-task methods treat all learning tasks and data sets equally, even thought we are usually mostly interested in learning one of them. This thesis is a case study about promoting predictive performance in a specific data set of interest in a multi-task setting by constraining the models for the learning tasks unevenly. The model for the data set of interest more sparse as compared to the models for the secondary data sets. To study the new approach, the research question is limited to the very specific and popular family of so-called topic models using Bayesian nonparametric priors. A new model is presented which enables us to study the effects of asymmetric sparsity. The effects of asymmetric sparsity are studied by using the new model on real data and toy data. Subtle beneficial effects of asymmetric sparsity are observed on toy data and the new model performs comparably to existing state-of-the-art methods on real data

Warriors of Buddhism: Buddhism and violence as seen from a Vajrayana Tibetan Buddhist perspective

Buddhism is considered by many today as the non-violent religion par excellence. The concept of ahimsa (non-violence) coupled with the notion of pratityasamutpada (i.e. that everything is casually interconnected, with the implication that pain inflicted upon others is therefore really done to oneself and thus to be avoided) seems to be one of the main arguments for promoting Buddhism as an excellent method for promoting world peace. However this non-violent, serene picture of Buddhism is not the only picture. Buddhists on occasion speak of a need to use violence, and employ it. Buddhists kill. Sometimes they also kill each other. The history as well as the present of Buddhist Asia is bloodstained. How do Buddhists justify approving of and using violence? How do they legitimise their pro-violent utterances and actions when such actions ought to result in excommunication? What are they saying? There are several answers to this, some of which are presented in this article, with the primary focus on Buddhist Tibet. 

Maltreatment-associated neurodevelopmental disorders: a co-twin control analysis

Background: Childhood maltreatment (CM) is strongly associated with psychiatric disorders in childhood and adulthood. Previous findings suggest that the association between CM and psychiatric disorders is partly causal and partly due to familial confounding, but few studies have investigated the mechanisms behind the association between CM and neurodevelopmental disorders (NDDs). Our objective was to determine whether maltreated children have an elevated number of NDDs and whether CM is a risk factor for an increased NDD ‘load’ and increased NDD symptoms when controlling for familial effects. Methods: We used a cross-sectional sample from a population-representative Swedish twin study, comprising 8,192 nine-year-old twins born in Sweden between 1997 and 2005. CM was defined as parent-reported exposure to emotional abuse/neglect, physical neglect, physical abuse, and/or sexual abuse. Four NDDs were measured with the Autism–Tics, AD/HD, and other comorbidities inventory. Results: Maltreated children had a greater mean number of NDDs than nonmaltreated children. In a co-twin control design, CM-discordant monozygotic twins did not differ significantly for their number of NDDs, suggesting that CM is not associated with an increased load of NDDs when genetic and shared environmental factors are taken into account. However, CM was associated with a small increase in symptoms of attention-deficit/hyperactivity disorder and autism spectrum disorder in CM-discordant MZ twins, although most of the covariance of CM with NDD symptoms was explained by common genetic effects. Conclusions: Maltreated children are at higher risk of having multiple NDDs. Our findings are, however, not consistent with the notion that CM causes the increased NDD load in maltreated children. Maltreated children should receive a full neurodevelopmental assessment, and clinicians should be aware that children with multiple NDDs are at higher risk of maltreatment

Screening, intervention and outcome in autism and other developmental disorders: the role of randomized controlled trials

We draw attention to a number of important considerations in the arguments about screening and outcome of intervention in children with autism and other developmental disorders. Autism screening in itself never provides a final clinical diagnosis, but may well identify developmental deviations indicative of autism—or of other developmental disorders—that should lead to referral for further clinical assessment. Decisions regarding population or clinic screening cannot be allowed to be based on the fact that prospective longitudinal RCT designs over decades could never be performed in complex developmental disorders. We propose an alternative approach. Early screening for autism and other developmental disorders is likely to be of high societal importance and should be promoted and rigorously evaluated