90 research outputs found

    Water bottle flipping physics

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    The water bottle flipping challenge consists of spinning a bottle, partially filled with water, and making it land upright. It is quite a striking phenomenon, since at first sight, it appears rather improbable that a tall rotating bottle could make such a stable landing. Here, we analyze the physics behind the water bottle flip, based on experiments and an analytical model that can be used in the classroom. Our measurements show that the angular velocity of the bottle decreases dramatically, enabling a nearly vertical descent and a successful landing. The reduced rotation is due to an increase in the moment of inertia, caused by the in-flight redistribution of the water mass along the bottle. Experimental and analytical results are compared quantitatively, and we demonstrate how to optimize the chances for a successful landing.</p

    Large slow-roll corrections to the bispectrum of noncanonical inflation

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    Nongaussian statistics are a powerful discriminant between inflationary models, particularly those with noncanonical kinetic terms. Focusing on theories where the Lagrangian is an arbitrary Lorentz-invariant function of a scalar field and its first derivatives, we review and extend the calculation of the observable three-point function. We compute the "next-order" slow-roll corrections to the bispectrum in closed form, and obtain quantitative estimates of their magnitude in DBI and power-law k-inflation. In the DBI case our results enable us to estimate corrections from the shape of the potential and the warp factor: these can be of order several tens of percent. We track the possible sources of large logarithms which can spoil ordinary perturbation theory, and use them to obtain a general formula for the scale dependence of the bispectrum. Our result satisfies the next-order version of Maldacena's consistency condition and an equivalent consistency condition for the scale dependence. We identify a new bispectrum shape available at next-order, which is similar to a shape encountered in Galileon models. If fNL is sufficiently large this shape may be independently detectable.Comment: v1: 37 pages, plus tables, figures and appendices. v2: supersedes version published in JCAP; some clarifications and more detailed comparison with earlier literature. All results unchanged. v3:improvements to some plots; text unchange

    Еволюція топоформанта -щина в слов’янських мовах та його рефлекси в реґіональній історичній ойконімії

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    У статті автор на широкому географічно-історичному тлі простежує еволюцію топоформанта -щина в слов'янській топонімії детально аналізує рефлекси цього суфікса в реґіональній історичній ойконімії на прикладі дев'яти назв (і 12-ти мікроойконімних варіантів) населених пунктів Галицької та Львівської земель Руського воєводства із подальшим встановленням їхньої етимологи.В статье автор на широком географическо-историческом фоне прослеживает эволюцию топонимического форманта -щина в славянской топонимии детально анализирует рефлексы этого суффикса в региональной исторической ойконимии на примере девяти названий (с 12-ю микроойконимными вариантами) населенных пунктов Галицкой и Львовской земель Русского воеводства с последующим установлением их этимологии.The author traces the evolution of topoformant -schyna on the basis of historical and geographical studies in Slavic Toponymy. Reflexes of the suffix are analyzed in regional historical oykonymy in 12 toponyms (and their 12 microokonymic variants) of villages and towns of Halych and Lviv Lands of Ruske Woyewodstwo. Their etymology is also analysed

    Prevalence of- and risk factors for work disability in Dutch patients with inflammatory bowel disease

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    AIM to determine the prevalence of work disability in inflammatory bowel disease (IBD), and to assess risk factors associated with work disability. METHODS For this retrospective cohort study, we retrieved clinical data from the Dutch IBD Biobank on July 2014, containing electronic patient records of 3388 IBD patients treated in the eight University Medical Centers in the Netherlands. Prevalence of work disability was assessed in 2794 IBD patients and compared with the general Dutch population. Multivariate analyses were performed for work disability (sick leave, partial and full disability) and long-Term full work disability (> 80% work disability for > 2 years). RESULTS Prevalence of work disability was higher in Crohn's disease (CD) (29%) and ulcerative colitis (UC) (19%) patients compared to the general Dutch population (7%). In all IBD patients, female sex, a lower education level, and extra-intestinal manifestations, were associated with work disability. In CD patients, an age > 40 years at diagnosis, disease duration > 15 years, smoking, surgical interventions, and anti-TNFα use were associated with work disability. In UC patients, an age > 55 years, and immunomodulator use were associated with work disability. In CD patients, a lower education level (OR = 1.62, 95%CI: 1.02-2.58), and in UC patients, disease complications (OR = 3.39, 95%CI: 1.09-10.58) were associated with long-Term full work disability. CONCLUSION The prevalence of work disability in IBD patients is higher than in the general Dutch population. Early assessment of risk factors for work disability is necessary, as work disability is substantial among IBD patients

    Effectiveness and safety of tofacitinib for ulcerative colitis: two-year results of the ICC Registry

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    Background Tofacitinib is an oral Janus kinase (JAK) inhibitor and is registered for the treatment of ulcerative colitis (UC). The effectiveness of tofacitinib has been evaluated up to 12 months of treatment. Aim The aim of this study was to assess the effectiveness and safety of 24 months of tofacitinib use in UC patients in the Netherlands. Methods Patients initiating tofacitinib treatment were included in the ICC Registry, a nationwide, observational registry. Patients were prospectively evaluated for up to 24 months. The primary outcome was corticosteroid-free clinical remission (CSFR, Simple Clinical Colitis Activity Index [SCCAI] <= 2) at week 104. Secondary outcomes included biochemical remission (C-reactive protein (CRP) <= 5 mg/L and faecal calprotectin (FC) <= 250 mu g/g), safety, and discontinuation rate. Results We included 110 patients of whom 104 (94.5%) were anti-TNF experienced. After 104 weeks of tofacitinib, 31.8% (34/107) were in CSFR, 23.4% (25/107) in biochemical remission and 18.7% (20/107) in combined clinical and biochemical remission. Of the patients in CSFR at week 52, 76.5% (26/34) remained so after 104 weeks of treatment. Sixty-one patients (55.5%) discontinued tofacitinib after a median duration of 13 weeks (IQR 7-34). The main reasons for discontinuation were non-response (59%), loss of response (14.8%), and adverse events (18%). There were 33.9 possible tofacitinib-related adverse events per 100 patient-years during follow-up. Adverse events most probably related to tofacitinib were skin reactions and headaches. There were 6.4 herpes zoster infections per 100 patient-years. Conclusion Tofacitinib was effective in 31.8% of patients after 24 months of treatment.Cellular mechanisms in basic and clinical gastroenterology and hepatolog
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