bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel approach to detect and characterize the scattering patterns of single Au nanoparticles using confocal microscopy
Authors: ZÜCHNER T. , FAILLA A. V. , HARTSCHUH A. , MEIXNER A. J. 
Published: February 2008

SummaryWe demonstrate a novel optical method for characterizing single Au nanoparticles by acquiring their scattering patterns. This technique combines confocal microscopy and higher‐order laser modes for detecting the light scattered by sub‐wavelength–sized nanoobjects. The optical patterns are generated by the coherent superposition of the field scattered by individual metallic particles and the excitation field reflected at the cover slide–air interface and provide information about the particles' position, orientation, size and shape. Detectable changes in the full width at half maximum (FWHM) of the signal intensity permit to distinguish between 20‐ and 60‐nm diameter Au spheres. The confocal images are also very sensitive to the particle's geometry and polarizability, that is, Au nanospheres, Au nanorods and triangular Au nanoplates give different characteristic patterns if the excitation wavelength is varied.
Near‐field–induced tunability of surface plasmon polaritons in composite metallic nanostructures
Authors: CHRIST A. , LÉVÊQUE G. , MARTIN O. J. F. , ZENTGRAF T. , KUHL J. , BAUER C. , GIESSEN H. , TIKHODEEV S. G. 
Published: February 2008

SummaryWe numerically study near‐field–induced coupling effects in metal nanowire‐based composite nanostructures. Our multi‐layer system is composed of individual gold nanowires supporting localized particle plasmons at optical wavelengths, and a spatially separated homogeneous silver slab supporting delocalized surface plasmons. We show that the localized plasmon modes of the composite structure, forming so‐called magnetic atoms, can be controlled over a large spectral range by changing the thickness of the nearby metal slab. The optical response of single‐wire and array‐based metallic structures are compared. Spectral shifts due to wire–mirror interaction as well as the coupling between localized and delocalized surface plasmon modes in a magnetic photonic crystal are demonstrated. The presented effects are important for the optimization of metal‐based nanodevices and may lead to the realization of metamaterials with novel plasmonic functionalities.
Beyond lock‐in analysis for volumetric imaging in apertureless scanning near‐field optical microscopy
Authors: VOGELGESANG R. , ESTEBAN R. , KERN K. 
Published: February 2008

SummaryConventional apertureless scanning near‐field optical microscopy uses lock‐in demodulation techniques to filter higher harmonics from the periodically modulated optical signal. On the one hand, this signal notoriously may contain contaminating mechanical contributions; on the other, it reduces the available data to one number per pixel. Realizing that the vertically oscillating near‐field probe actually traverses a whole volume above the sample surface, we discuss a model to extend the data analysis in an attempt to better extract the optical information and to recover its three‐dimensional spatial distribution.
Characterization of Trypanosoma brucei dihydroorotate dehydrogenase as a possible drug target; structural, kinetic and RNAi studies
Authors: Arakaki Tracy L. , Buckner Frederick S. , Gillespie J. Robert , Malmquist Nicholas A. , Phillips Margaret A. , Kalyuzhniy Oleksandr , Luft Joseph R. , DeTitta George T. , Verlinde Christophe L. M. J. , Van Voorhis Wesley C. , Hol Wim G. J. , Merritt Ethan A. 
Published: February 2008

SummaryNucleotide biosynthesis pathways have been reported to be essential in some protozoan pathogens. Hence, we evaluated the essentiality of one enzyme in the pyrimidine biosynthetic pathway, dihydroorotate dehydrogenase (DHODH) from the eukaryotic parasite Trypanosoma brucei through gene knockdown studies. RNAi knockdown of DHODH expression in bloodstream form T. brucei did not inhibit growth in normal medium, but profoundly retarded growth in pyrimidine‐depleted media or in the presence of the known pyrimidine uptake antagonist 5‐fluorouracil (5‐FU). These results have significant implications for the development of therapeutics to combat T. brucei infection. Specifically, a combination therapy including a T. brucei‐specific DHODH inhibitor plus 5‐FU may prove to be an effective therapeutic strategy. We also show that this trypanosomal enzyme is inhibited by known inhibitors of bacterial Class 1A DHODH, in distinction to the sensitivity of DHODH from human and other higher eukaryotes. This selectivity is supported by the crystal structure of the T. brucei enzyme, which is reported here at a resolution of 1.95 Å. Additional research, guided by the crystal structure described herein, is needed to identify potent inhibitors of T. brucei DHODH.
Variability in the Italian population of Gnomonia leptostyla, homothallism and resistance of Juglans species to anthracnose
Authors: Belisario A. , Scotton M. , Santori A. , Onofri S. 
Published: February 2008

SummaryIsolations of Gnomonia leptostyla were carried out in 13 plantations of Juglans regia distributed throughout Italy, including Sardinia and Sicily. Mean diameter of colonies grown in vitro at 22°C and sporulation of 191 isolates, grouped by site of collection, were compared. Four groups of isolates, from environmentally diverse sites, were more thoroughly investigated for the effect of temperature (from 10 to 30°C, 5°C increment) on growth and sporulation. Colony growth of isolates within groups correlated with temperature and environmental parameters at the site of collection, such as temperature, rainfall, number of rain days per month and per year, and altitude. Altitude and mean temperature in April correlated with colony growth. In general, the isolates that grew significantly more slowly were from sites with colder early springs and higher altitudes. More significant data were obtained comparing isolates from different sites obtained from the same walnut cultivar or population. The host source was more significantly correlated with colony growth within the same site of collection. Acervular conidiomata were abundantly produced by all isolates at 22°C in darkness after 21 days, while protoperithecia were produced within 2 months by most isolates, under the same conditions. Similarly, the four groups of isolates tested at different temperatures produced conidiomata at 20 and 25°C, but not at 10, 15 and 30°C. After 2 months, protoperithecia were present in most isolates at 20°C, very few at 25 and 15°C, and no production was recorded at 10 and 30°C. Fertile perithecia with asci and ascospores were produced, after 3 months at 10°C in darkness, by six homothallic isolates out of 38 tested. In general, perithecia were larger than protoperithecia both in ascocarp diameter and in neck length. Ascocarp diameter, width of asci and length of ascopores of in vitro‐produced perithecia were larger than those of perithecia produced in nature. The latter showed a neck length longer than in vitro‐produced perithecia. Virulence of isolates when inoculated on J. regia was correlated with colony growth rate, but rated independently for homothallic or heterothallic isolates. A preliminary screening for sources of resistance to anthracnose in the genus Juglans showed J. sieboldiana and J. cinerea to be highly resistant and both J. nigra and J. hindsii to be highly susceptible to the disease. Juglans regia showed an intermediate response of susceptibility to anthracnose.
Apoptotic Changes in the Epithelium Germinativum of the Cat (Felis catus s. domestica, L. 1758) at Different Ages and Breeding Seasons
Authors: Siemieniuch MJ 
Published: February 2008

ContentsApoptosis (programmed cell death) could be considered as a physiological process that takes part in a healthy organism, which helps to maintain organism homeostasis. The visible deterioration of semen quality and the number of germ cells is accompanied by a seasonal decrease of the reproductive activity in some species. This post‐effect cascade is caused by apoptosis, which is the primary mechanism responsible for the elimination of germ cells during spermatogenesis. The aim of our study was to assess apoptotic changes in the epithelium germinativum in cat testes at different ages. One hundred and two pairs of testes were obtained from domestic cats aged between 4 months and 10 years. The paraffin‐embedded tissue sections were labelled using the Oncogene and Calbiochem Research Products DNA Fragmentation Detection Kit (Cat# QIA21; Darmstadt, Germany), which allows the recognition of apoptotic nuclei in tissue sections with Fragment End Labelling (FragELTM) of DNA. The activity of apoptotic processes in cat testes collected from the spring‐summer period compared with the autumn‐winter season revealed that, 59.42% and 51.51%, respectively, males testes were characterized by insignificant changes. The obtained data revealed a distinctive apoptotic changes in the young animal testes before spermatogenesis onset. An intensification of programmed death cells in the epithelium germinativum in the elder cats (between 3–6 and 6–10 years) was not observed. Apoptotic changes slightly intensified in cats aged between 12 and 36 months.
GABA Control of GnRH Release from the Ewe Hypothalamus In Vitro: Sensitivity to Oestradiol
Authors: Ghuman SPS , Jones DN , Prabhakar S , Smith RF , Dobson H 
Published: February 2008

ContentsThe present study examines the involvement of GABAA or B receptors in gonadotrophin‐releasing hormone (GnRH) release in vitro and determines whether oestradiol modulates γ‐aminobutyric acid (GABA)–GnRH interaction. Within 10 min after ewe killing, hypothalamic slices were dissected and placed in oxygenated Minimum Essential Media (MEM)‐α at 4°C; within 2 h, slices were singly perifused at 37°C with oxygenated MEM‐α (0.15 ml/min), with or without oestradiol (24 pg/ml). After 4 h equilibration, fractions were collected for 4 h interposed with a 10 min exposure to specific GABAA or B receptor ligands (0.1–10 mm). The GABAA or B agonists (muscimol or baclofen) did not greatly influence GnRH release. However, GnRH increased (p < 0.05) after exposure to 10 mm GABAA or B antagonists (bicuculline or CGP52432, respectively). The GABAA antagonist stimulated greater sustained GnRH release (p < 0.05) in the absence of oestradiol than in its presence. The bioactivity of the released GnRH was studied using a hypothalamus‐pituitary sequential double‐chamber perifusion. Only after exposure of hypothalamic slices to the GABAA antagonist, did the hypothalamic eluate stimulate luteinizing hormone release from pituitary fragments (p < 0.05) confirming that the GABAA antagonist stimulated release of biologically active GnRH. In summary, GnRH release from the hypothalamus is predominantly under GABAA receptor inhibitory control and this is attenuated in the presence of oestradiol.
THE “ CAUTION‐LEVEL ” IN MULTIPLE TESTS OF SIGNIFICANCE
Authors: Verhagen A. M. W. 
Published: February 2008

SummaryThe paper produces a measure for the reliability of multiple assertions arrived at with multile tests of significance. it is called the caution level and in the case of single tests it reduces to the well know significance level.The caution level is introduced and discussed in relation to n independent test statistics for n different null hypotheses. Its value c is given by c = l ‐(l ‐α)n‐(r‐1) where α is the level of significance of the individual tests and r is the observed number of significant test statistics. The caution level is applied to some experimental data and worked out in detail for the case n=2. The caution level depends on the observed number of significant test‐statistics and is therefore closely geared to the actual outcome of the experiment. This gives it an advantage over the “experimentwise error rate” proposed by Tukey (1953), since the latter becomes more unrealistic as the number r of significant test‐statistics increases.The caution level turns out to be well suited for designing multiple tests in which the caution level is the same irrespective of the possible multiple assertion to which the test may lead. The construction of tests with the caution level equalized over all possible assertions involves only the distribution of the largest of ν independent rectangular variates in the range (0, 1). Such a test is illustrated graphically for thc case n=2.Just as the significance level in the case of a single test, so the caution level provides a, starting point for the study of errors of the second kind, both in the absence and in the presence of prior distribuions, for the more general multiple‐test situation and thus opens up a wide field of investigation. At a later stage the author proposes to extend the use of the caution level to more complicated situations involving studentized test‐statistics dependent through a common denominator and to correlated test statistics consisting of differences between means.
NOTE ON THE NON‐EXISTENCE OF A MAXIMUM LIKELIHOOD ESTIMATE1
Authors: Konijn H. S. 
Published: February 2008

SummaryIt is shown that in a regression model with intraclass correlation ρ, maximum likelihood estimates and minimum variance unbiased linear estimates of the regression coefficients are unaffected by the value of ρ when ρ is given, and that the former do not exist when ρ is not specified. The usual confidence intervals for the regression slopes remain valid, but there are difficulties in giving a confidence interval for the intercept.
SOME CONTRIBUTIONS TO TWO‐PHASE SAMPLING
Authors: Singh D. , Singh B. D. 
Published: February 2008

SummaryA new two‐phase sampling procedure is suggested in this paper. The information on the ancillary variate in the preliminary sample is used for selecting the units for sub‐sample with unequal probabilities. Unbiased estimators for the population mean and their variance expressions are obtained for sub‐sampling procedures, both with and without replacement.
QUASI‐STATIONARY BEHAVIOUR IN THE RANDOM WALK WITH CONTINUOUS TIME
Authors: Seneta E. 
Published: February 2008

SummaryThe long‐term behaviour of the random walk on the positive integers is discussed. In particular, one distribution describing this behaviour when there is a non‐zero drift in one direction, is shown to be of discrete gamma‐type. Under the same condition, the effectively ultimate time to absorption is exponential.
AN INVENTORY PROBLEM APPLIED TO A RENTAL SITUATION
Authors: Jain H. C. 
Published: February 2008

SummaryAn inventory problem, applied to a rental situation business, has been considered. If no item is in stock when a demand occurs, the company borrows the units from other concerns in the same line of business. The profit function has been calculated and it has been shown how the inventory level increases with penalty cost.A review of the literature on inventory control reveals that not much work has been done in holding inventories of rental items. In a recent paper, Tainiter (1964) considered the situation in which a company rents out items such as cars, trucks, farm equipment, books, furniture, etc., and obtained the profit function by taking “rental‐out” time as a negative exponential and demand as a general random variable. The model is equally applicable to companies which rent out “service personnel”, repair men, taxi cabs, etc.“We consider a company renting out items to customers. The company starts its business by purchasing a total number of M items in the inventory. The term inventory, defined by Arrow, Earlin and Scarf (1958) as the stock of goods which is kept for future sale or production, is applicable here. Whenever a demand occurs the item is rented out immediately, if it is available in the stock. But if the inventory is zero, i.e. all the items are rented out, the demand will be satisfied by borrowing items from other companies which are dealing in the same line of business. For example, a manufacturer of refrigerators maintains and repairs his product at the customer's house after sale. If a complaint arrives when no repairmen are available, the company will “borrow” repairmen from elsewhere and will attend to the complaint immediately. The borrowing cost may be negative or positive, representing a penalty or a profit. On the other hand if the company does not borrow and the customer has to wait (and such situations occur very often) the loss of the customer's goodwill may occur. It is also not possible to keep large numbers of items because of the storage costs and tied up capital. The problem is then to devise an optimal policy such that the profits of the company are maximized.
A NOTE ON CONFIDENCE BOUNDS FOR CERTAIN RATIOS OF CHARACTERISTIC ROOTS OF COVARIANCE MATRICES
Authors: Krishnaiah P. R. , Pathak P. K. 
Published: February 2008

SummaryLet σ1, …, σk be the covariance matrices of k p‐variate normal populations. Let Λij be the jth largest characteristic root of σi (j=1, …, p; i=1, …, k). In this note we obtain simultaneous confidence intervals on (i)Λi+1, p/Λipand by using methods similar to those of Khatri (1965).
A LIMIT THEOREM FOR THE GALTON‐WATSON PROCESS WITH IMMIGRATION
Authors: Quine M. P. , Seneta E. 
Published: February 2008

SummaryIt is difficult, in general, to optain an explicit expression for the limiting‐stationary distribution, when such a distribution exists, of the process in which teh individuals reproduce as in a Galton‐Wastson process, but are also subject to an independent immigration component at each generation. The main result of this paper is a limit theorem which suggests a means of approximating this distribution by a gamma density, when the mean of the offspring distribution is less than, but close to, unity. Following along the same lines, it is easy to show that a similar limit theorem holds for the asymptotic conditional limit distribution of an ordinary subcritical Galton‐Watson process, whereby this distribution approaches the exponential as the offspring mean approaches unity.
TESTING THE EQUALITY OF PARAMETERS IN THE DISTRIBUTIONS WHEN THE RANGE DEPENDS UPON THE PARAMETER
Authors: Khatri C.G. , Jaiswal M. C. 
Published: February 2008

AbstractThe authors derive the null and non‐null distributions of the test statistic v=ymin/ymax (where ymin= min xij, ymax= max xij, J=1,2, …, k) connected with testing the equality of scale parameters θ1, θ2, …θk in certain, class of density functions given by
The Multiplicative Definition of Interaction
Authors: Lancaster H. O. 
Published: February 2008

SummaryThe theory of the multiplicative definition of second order interaction is considered. Necessary and sufficient conditions in terms of the correlations in the marginal two‐dimensional distributions are found for the existence of a “perfect” set of probabilities. Some progress is reported on the proof of the uniqueness of the multiplicative set of probabilities for a given set of two‐dimensional distributions. The multiplicative property of such sets is preserved under pooling of marginal sets only in trivial cases, and so the multiplicative definition cannot be said to be a straightforward generalization from the definition of no interaction in two‐dimensional distributions.
Further Studies on Two Queues in Parallel
Authors: Hunter Jeffrey J. 
Published: February 2008

SummaryThis paper presents some further results related to a queueing model originally suggested by the author: “Two queues in parallel” (J. Boy. Statist. Soc, Ser. B, 31, 432–445, 1969).A detailed study of the model under the imposition of finite waiting rooms when each queue can accommodate at most two customers illustrates the complexity of the problems involved. However, this study leads to some results concerning the nature of the equilibrium probabilities in the more general finite waiting room cases.A study of the correlation between the input distributions and the correlation of the queue size distributions gives rise to some general conjectures concerning these relationships.
Maximum Likelihood Estimation in the Bivariate Binomial (0,1) Distribution:Application TO 2×2 Tables
Authors: Hamdan M. A. , Martinson E. O. 
Published: February 2008

SummaryWe consider a 2×2 contingency table, with dichotomized qualitative characters (A,A) and (B,B), as a sample of size n drawn from a bivariate binomial (0,1) distribution. Maximum likelihood estimates p̂1p̂2 and p̂ are derived for the parameters of the two marginals p1p2 and the coefficient of correlation. It is found that p̂ is identical to Pearson's (1904)ϕ=(χ2/n)½, where ϕ2 is Pearson's usual chi‐square for the 2×2 table. The asymptotic variance‐covariance matrix of p̂lp̂2and p is also derived.
THE LIMITING FORM OF THE NON‐CENTRAL WISHART DISTRIBUTION1,2
Authors: Jensen D.B. 
Published: February 2008

SUMMARYLet S (p×p) have a Wishart distribution ‐with v degrees of freedom and non‐centrality matrix θ= [θjK] (p×p). Define θ0= min {| θjk |}, let θ0→∞, and suppose that | θjK | = 0(θo). Then the limiting form of the standardized non‐central distribution, as θ while &#x006e;̈ remains fixed, is a multivariate Gaussian distribution. This result in turn is used to obtain known asymptotic properties of multivariate chi‐square and Rayleigh distributions under somewhat weaker conditions.
CONFIDENCE INTERVALS FOR POWER, WITH SPECIAL REFERENCE TO MEDICAL TRIALS*
Authors: Dudewicz Edward J. 
Published: February 2008

AbstractA technique is given for drawing valid inferences in cases where performance characteristics of statistical procedures (e.g. power for a test, or probability of a correct selection for a selection procedure) depend upon unknown parameters (e.g. an unknown variance). The technique is especially useful in situations where sample sizes are small (e.g. in many medical trials); the “usual” approximate procedures are found to be misleading in such cases.
HORVITZ‐THOMPSON AND DES RAJ ESTIMATORS REVISITED
Authors: Rao T. J. 
Published: February 2008

SummaryIn this paper it is shown that the generalized πPS sampling strategy consisting of the design with πi, the probability of inclusion of the ith unit in the sample, proportional to the modified size together with the corresponding Horvitz‐Thompson estimator (Rao, 1971), is superior to the symmetrized Des Raj strategy under a general super‐population set‐up for all values of the super‐population parameter g, when the samples are of size two.
HOUSEHOLD CONSUMPTION OF FOOD IN AUSTRALIA
Authors: Podder N. 
Published: February 2008

This paper is the second (see the first reference) in the series of studies entitled “Household Consumption and Income in Australia.” undertaken by the author to analyse data from an Australia‐wide consumption survey (Drane, Edwards and Gates, 1969). Whereas the first study was an investigation into the overall consumption patterns, the present study is devoted to analysing intensively the patterns of household food consumption. Food is especially important since it is the largest single consumption item in the family budget. In this paper the analysis is extended in two main directions. The first is the disaggregation of total food consumption into its components. The degree of disaggregation, however, is limited by the availability of detailed information. Accordingly, only five components of expenditure on food could be effectively considered. The second direction is the investigation of the possible differences in food consumption patterns among various sociological and demographic groups. To that end multivariate statistical techniques have been employed.The first section of this paper gives a brief description of the scope and limitations of the study and sets out different hypotheses that could be tested. The second section discusses the appropriate statistical techniques and the estimation methods that would be useful, while the results and their exposition have been presented in the third section. The final section contains a short comparative study and a few concluding remarks.