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A Multivariate Student’s t-Distribution

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Open Journal of Statistics 2016年第3期6卷 443-450页

作者： daniel t. Cassidy Department of Engineering Physics McMaster University Hamilton ON Canada

A multivariate Student’s t-distribution is derived by analogy to the derivation of a multivariate normal (gaussian) probability density function. this multivariate Student’s t-distribution can have different shape parameters for the marginal probability density functions of the multivariate distribution. Expressions for the probability density function, for the variances, and for the covariances of the multivariate t-distribution with arbitrary shape parameters for the marginals are given.

关键词： Multivariate Student’s t Variance Covariance Arbitrary Shape Parameters

Student’s t Increments

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Open Journal of Statistics 2016年第1期6卷 156-171页

作者： daniel t. Cassidy Department of Engineering Physics McMaster University Hamilton Canada

Some moments and limiting properties of independent Student’s t increments are studied. Inde-pendent Student’s t increments are independent draws from not-truncated, truncated, and effectively truncated Student’s t-distributions with shape parameters and can be used to create random walks. It is found that sample paths created from truncated and effectively truncated Student’s t-distributions are continuous. Sample paths for Student’s t-distributions are also continuous. Student’s t increments should thus be useful in construction of stochastic processes and as noise driving terms in Langevin equations.

关键词： Student’s t-Distribution truncated Effectively truncated Cauchy Distribution Random Walk Sample Paths Continuity

Segment boundaries of the adult rat epididymis limit interstitial signaling by potential paracrine factors and segments lose differential gene expression after efferent duct ligation

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Asian Journal of Andrology 2007年第4期9卷 565-573页

作者： terry t. tumer daniel S. Johnston Scott A. Jelinsky Jose L. tomsig Joshua N. Finger Department of Urology University of Virginia Health Science System Charlottesville VA 22908 US Cell Biology University of Virginia Health Science System Charlottesville VA 22908 US Contraception Women＇s Health and Musculoskeletal Biology Wyeth Research Collegeville PA 19426 USA Biological technologies Molecular Profiling and Biomarker Discovery Wyeth Research Cambridge MA 02140 USA

the epididymis is divided into caput, corpus and cauda regions, organized into intraregional segments separated by connective tissue septa （CtS）. In the adult rat and mouse these segments are highly differentiated. Regulation of these segments is by endocrine, lumicrine and paracrine factors, the relative importance of which remains under investigation. Here, the ability of the CtS to limit signaling in the interstitial compartment is reviewed as is the effect of 15 days of unilateral efferent duct ligation （EDL） on ipsilateral segmental transcriptional profiles. Inter-segmental microperifusions of epidermal growth factor （EgF）, vascular endothelial growth factor （VEgFA） and fibroblast growth factor 2 （FgF2） increased phosphorylation of mitogen activated protein kinase （MAPK） in segments 1 and 2 of the rat epididymis and the effects of all factors were limited by the CtS separating the segments. Microan＇ay analysis of segmental gene expression determined the effect of 15 days of unilateral EDL on the transcriptome-wide gene expression of rat segments 1-4. Over 11 000 genes were expressed in each of the four segments and over 2 000 transcripts in segment 1 responded to deprivation of testicular lumicrine factors. Segments 1 and 2 of control tissues were the most transcriptionally different and EDL had its greatest effects there. In the absence of lumicrine factors, all four segments regressed to a transcriptionally undifferentiated state, consistent with the less differentiated histology. Deprivation of lumicrine factors could stimulate an individual gene＇s expression in some segments yet suppress it in others. Such results reveal a higher complexity of the regulation of rat epididymal segments than that is generally appreciated. （Asian J Androl 2007 July; 9： 565-573）

关键词： efferent duct ligation dedifferentiation proximal epididymis

Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess

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Frontiers of Chemical Science and Engineering 2020年第1期14卷 28-40页

作者： daniel t.Payne Mandeep KChahal Vaclav Brezina Whitney A.Webre Katsuhiko Ariga Francis D’Souza Jan Labuta Jonathan P.Hill WPI Center for Materials Nanoarchitectonics National Institute for Materials ScienceIbaraki 305-0044Japan Department of Macromolecular Physics Faculty of Mathematics and PhysicsCharles University18000 PragueCzech Republic Department of Chemistry University of North TexasDentonTX 76203USA Department of Advanced Materials Science Graduate School of Frontier SciencesThe University of TokyoChiba 277-8561Japan

Chiral 1,1’-binaphthyl-linked diporphyrin‘tweezers’(R)-1/(S)-1 and the corresponding zinc(II)complexes(R)-2/(S)-2 were prepared as chiral host molecules,and their utility for chiral analyses(especially enantiomeric excess(ee)determinations)were ***(1-n-dodecyl)porphyrins were used for the first time as the interacting *** capabilities of the diporphyrin tweezers were investigated by titrations with(R,R)-and(S,S)-cyclohexane-1,2-diamine(CHDA).the host molecules could be used as multichannel probes of ee by using UVvis,circular dichroism(CD),fluorescence emission and 1H nuclear magnetic resonance(1 H-NMR)*** configurations could also be differentiated using CD or 1HNMR *** three optical techniques give good resolution of ee with reasonable sensitivity considering the low concentrations used(ca.10^-6 mol·L^-1).the ee determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of(R,R)-and(S,S)-***-metallated(R)-1/(S)-1 hosts could not be used to detect chiral information in a strongly acidic chiral *** work demonstrates the utility of 1,1’-binapthyllinked chiral hosts for chiral analysis of ditopically interacting enantiomers.

关键词： porphyrin dimer chirality enantiomeric excess CD fluorescence

Relating environmental variables with aquatic community structure in an agricultural/urban coldwater stream

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Ecological Processes 2021年第1期10卷 481-499页

作者： daniel t.L.Myers Richard R.Rediske James N.McNair Aaron D.Parker E.Wendy Ogilvie Annis Water Resources Institute Grand Valley State University740 W Shoreline DriveMuskegonMI 49401USA. Michigan Department of Environment Great Lakesand Energy525 W Allegan StreetLansingMI 48909USA. grand Valley Metropolitan Council 678 Front Avenue NWSuite 200Grand RapidsMI 49504USA.

Background:Urban areas are often built along large rivers and surrounded by agricultural *** may lead to small tributary streams that have agricultural headwaters and urbanized lower *** study objectives assessed are as follows:(1)landscape,geomorphic,and water quality variables that best explained variation in aquatic communities and their integrity in a stream system following this agricultural-to-urban land use gradient;(2)ways this land use gradient caused aquatic communities to differ from what would be expected for an idealized natural stream or other longitudinal gradients;and(3)whether the impacts of this land use gradient on aquatic communities would grow larger in a downstream direction through the agricultural and urban *** study area was an impaired coldwater stream in Michigan,***:Many factors structured the biological communities along the agricultural-to-urban land use *** woody debris had the strongest relationship with EPt(Ephemeroptera,Plecoptera,and trichoptera)abundance and richness and were most common in the lower,urbanized *** streambed substrate had the strongest relationship with Diptera taxa and surface air breather macroinvertebrates and was dominant in agricultural *** community assemblage was influenced largely by stream flow and temperature regimes,while poor fish community integrity in lower urban reaches could be impacted by geomorphology and episodic urban pollution *** macroinvertebrates were most abundant in deforested,first-order agricultural headwaters,while EPt macroinvertebrate richness was the highest downstream of agricultural areas within the urban zone that had extensive forest ***:Environmental variables and aquatic communities would often not conform with what we would expect from an idealized natural *** richness improved downstream of agricultural *** shows promise for the recovery of aquatic systems using we

关键词： Land use Habitat Stream Fish Macroinvertebrate gradient

Potential impact of combined inhibition of 3a-oxidoreductases and 5a-reductases on prostate cancer

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Asian Journal of Urology 2019年第1期6卷 50-56页

作者： Michael V.Fiandalo daniel t.gewirth James L.Mohler Department of Urology Roswell Park Comprehensive Cancer CenterBuffaloNYUSA Hauptman-Woodward Medical Research Institute BuffaloNYUSA

Prostate cancer(PCa)growth and progression rely on the interaction between the androgen receptor(AR)and the testicular ligands,testosterone and dihydrotestosterone(DHt).Almost all men with advanced PCa receive androgen deprivation therapy(ADt).ADt lowers circulating testosterone levels,which impairs AR activation and leads to PCa ***,ADt is palliative and PCa recurs as castration-recurrent/resistant PCa(CRPC).One mechanism for PCa recurrence relies on intratumoral synthesis of DHt,which can be synthesized using the frontdoor or primary or secondary backdoor *** metabolism inhibitors,such as those targeting 5a-reductase,aldo-keto-reductase family member 3(AKR1C3),or cytochrome P45017A1(CYP17A1)have either failed or produced only modest clinical *** goal of this review is to describe the therapeutic potential of combined inhibition of 5a-reductase and 3a-oxidoreductase enzymes that facilitate the terminal steps of the frontdoor and primary and secondary backdoor pathways for DHt *** of the terminal steps of the androgen metabolism pathways may be a way to overcome the shortcomings of existing androgen metabolism inhibitors and thereby delay PCa recurrence during ADt or enhance the response of CRPC to androgen axis manipulation.

关键词： Androstanediol Dihydrotestosterone Dutasteride 3a-oxidoreductases Androgen deprivation therapy Abiraterone

Caregiver burden is increased in Parkinson’s disease with mild cognitive impairment (PD-MCI)

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translational Neurodegeneration 2017年第1期6卷 165-173页

作者： Ann J.Jones Roeline g.Kuijer Leslie Livingston daniel Myall Kyla Horne Michael MacAskill toni Pitcher Paul t.Barrett tim J.Anderson John C.Dalrymple-Alford New Zealand Brain Research Institute 66 Stewart StreetChristchurch 8011New Zealand Department of Psychology University of CanterburyChristchurchNew Zealand Department of Medicine University of OtagoChristchurchNew Zealand Cognadev UK Ltd.SandtonSouth Africa Department of Neurology Christchurch HospitalChristchurchNew Zealand Brain Research New Zealand Centre of Research Excellence ChristchurchNew Zealand

Background:there is limited evidence on caregiver outcomes associated with mild cognitive impairment in patients with Parkinson’s disease(PD-MCI)and the coping strategies used by these ***:to investigate this relationship,we examined levels of burden,depression,anxiety,coping strategies and positive aspects of caregiving in the informal caregivers of 96 PD *** PD patients were classified using MDS-task Force Level II criteria as showing either normal cognition(PD-N;n=51),PD-MCI(n=30)or with dementia(PDD;n=15).Results:Mean Zarit Burden Interview(ZBI)score increased significantly between carers of PD-N(M=13.39,SD=12.22)compared to those of PD-MCI patients(M=22.00,SD=10.8),and between carers of PD-MCI and PDD patients(M=29.33,SD=9.59).Moreover,the proportion of carers showing clinically significant levels of burden(ZBI score≥21)also increased as the patients’cognitive status declined(18% for PD-N;60% for PD-MCI;and 80%for PDD)and was mirrored by an increasing amount of time spent providing care by the *** ZBI score was independent of patient neuropsychiatric symptoms,motor function,disease duration and time that caregivers spent *** use of different coping strategies increased with worsening ***,we found only equivocal evidence that the use of problem-focused,emotion-focused and dysfunctional coping mediated the association between patient cognitive status and caregiver burden,because the inverse models that used caregiver burden as the mediator were also ***:the study highlights the impact of Parkinson’s disease on those providing care when the patient’s cognition is poor,including those with *** well-being has important implications for caregiver support,nursing home placement and disease course.

关键词： Parkinson’s disease Mild cognitive impairment Zarit caregiver burden interview Coping Depression Anxiety Positive aspects of caregiving

targeted gene Knockouts Reveal Overlapping Functions of the Five Physcomitrella patens FtsZ Isoforms in Chloroplast Division, Chloroplast Shaping, Cell Patterning, Plant Development, and gravity Sensing

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Molecular Plant 2009年第6期2卷 1359-1372页

作者： Anja Martin daniel Lang Sebastian t. Hanke Stefanie J.X. Mueller Eric Sarnighausen Marco Vervliet-Scheebaum Ralf Reski Plant Biotechnology Faculty of Biology University of Freiburg Schaenzlestr. 1 79104 Freiburg Germany Centre for Biological Signalling Studies (bioss) University of Freiburg Alberststr. 19 79104 Freiburg Germany Spemann graduate School of Biology and Medicine (SgBM) University of Freiburg Alberststr. 19A 79104 Freiburg Germany

Chloroplasts and bacterial cells divide by binary fission. the key protein in this constriction division is FtsZ, a self-assembling gtPase similar to eukaryotic tubulin. In prokaryotes, FtsZ is almost always encoded by a single gene, whereas plants harbor several nuclear-encoded FtsZ homologs. In seed plants, these proteins group in two families and all are exclusively imported into plastids. In contrast, the basal land plant Physcomitrella patens, a moss, encodes a third FtsZ family with one member. this protein is dually targeted to the plastids and to the cytosol. Here, we report on the targeted gene disruption of all ftsZ genes in R patens. Subsequent analysis of single and double knockout mutants revealed a complex interaction of the different FtsZ isoforms not only in plastid division, but also in chloroplast shaping, cell patterning, plant development, and gravity sensing. these results support the concept of a plastoskeleton and its functional integration into the cytoskeleton, at least in the moss R patens.

关键词： Bryophyte cell wall gravitropism gtPase chloroplast plastoskeleton P patens moss.

Effective truncation of a Student’s <i>t</i>-Distribution by truncation of the Chi Distribution in a Chi-Normal Mixture

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Open Journal of Statistics 2012年第5期2卷 519-525页

作者： daniel t. Cassidy Department of Engineering Physics McMaster University Hamilton Canada

A Student’s t-distribution is obtained from a weighted average over the standard deviation of a normal distribution, σ, when 1/σ is distributed as chi. Left truncation at q of the chi distribution in the mixing integral leads to an effectively truncated Student’s t-distribution with tails that decay as exp (-q2t2). the effect of truncation of the chi distribution in a chi-normal mixture is investigated and expressions for the pdf, the variance, and the kurtosis of the t-like distribution that arises from the mixture of a left-truncated chi and a normal distribution are given for selected degrees of freedom 5. this work has value in pricing financial assets, in understanding the Student’s t--distribution, in statistical inference, and in analysis of data.

关键词： Asset Pricing Student’s t-Distribution Cauchy truncation Moments Kurtosis