A Latent Model to Detect Multiple Clusters of Varying Sizes

Summary This article develops a latent model and likelihood‐based inference to detect temporal clustering of events. The model mimics typical processes generating the observed data. We apply model selection techniques to determine the number of clusters, and develop likelihood inference and a Monte Carlo expectation–maximization algorithm to estimate model parameters, detect clusters, and identify cluster locations. Our method differs from the classical scan statistic in that we can simultaneously detect multiple clusters of varying sizes. We illustrate the methodology with two real data applications and evaluate its efficiency through simulation studies. For the typical data‐generating process, our methodology is more efficient than a competing procedure that relies on least squares.     

Further Study on the Statistical Test to Detect Spatial Pattern

In the study of spatial patterns, the statistic I' = (n — 1)s²/x was commonly used. In this paper, we found that x — s² has an approximated normal distribution with zero mean if the x_i's (i = 1 to n) are independent identically distributed Poisson variables. Based on this conclusion, the hypothesis that a point pattern is completely random can be tested directly. And a method for the test of spatial patterns was proposed which can be sued as an alternative to the Chi-square based dispersion index test.     

Use of the Mushroom Tissue Block Rapid Pitting Test to Detect Brown Blotch Pathogens

Isolates of an Arthrobacter species known to produce a positive host pathogenicity test were evaluated by the mushroom tissue block rapid pitting test. All 11 isolates of the Arthrobacter species yielded a positive test response. The time required for a positive test was the same for Pseudomonas tolaasi and the Arthrobacter species.     

Use of a Modified Spatial-Context Memory Test to Detect Amnestic Mild Cognitive Impairment

In this study we sought to differentiate participants with amnestic mild cognitive impairment (a-MCI) from those with mild dementia of Alzheimer’s type (m-DAT) and normal controls by modifying an existing test of spatial context memory (SCMT) designed so as to evaluate the function of brain regions affected in early m-DAT. We found that participants with a-MCI had better total scores on our modified SCMT than those with m-DAT. Furthermore, the locational memory subtest was able to discriminate between those with a-MCI and m-DAT. Additionally, compared with other screening tests, our spatial context memory test showed high sensitivity and specificity in discerning those with a-MCI from the normal population but, was relatively ineffective in discriminating a-MCI patients from those with m-DAT. We conclude that our modified test of SCMT is an effective tool for discriminating a-MCI from m-DAT and does so by detecting differences in locational memory.     

Comparative Study of Agar Diffusion Test and the NCCLS Macrobroth Method for In Vitro Susceptibility Testing of Candida spp.

We performed a prospective double-blind study to evaluate the correlation between inhibition zones obtained by a disk-diffusion test, using Neo-sensitabs of fluconazole (Rosco Diagnostica), and the MICs generated by the NCCLS macrobroth dilution assay. Eighty clinical isolates, representing 5 of the clinically relevant species of Candida, were tested simultaneously by both methods. A clear inverse correlation was found between the results obtained by both tests (r = −0.69). In addition, there was high degree of agreement between methods in the identification of susceptible isolates. However, the resistance definition by disk-diffusion test had a positive predictive value of only 17%. Our data support the hypothesis that Rosco Fluconazole Neo-sensitabs have potential as a screening test for the identification of Candida isolates susceptible to fluconazole. Resistant isolates should be further investigated by standardized broth procedures. This revised version was published online in June 2006 with corrections to the Cover Date.     

New Culture Medium Containing Ionic Concentrations of Nutrients Similar to Concentrations Found in the Soil Solution

A new growth medium which closely approximates the composition of the soil solution is presented. This soil solution equivalent (SSE) medium contains the following components (millimolar): NO₃, 2.5; NH₄, 2.5; HPO₄, 0.005; Na, 2.5; Ca, 4.0; Mg, 2.0; K, 0.503; Cl, 4.0; SO₄, 5.0; ethylenediamine-di(o-hydroxyphenylacetic acid), 0.02; and MES [2-(N-morpholino)ethanesulfonic acid] (to maintain the pH at 6.0), 10, plus 0.1% arabinose. The advantages of the SSE medium are discussed.     

Development of Artificial-Sebum-Containing Leeming and Notman Agar Medium to Enhance the Growth of Malassezia

Mycopathologia - Modified Leeming and Notman agar medium (mLNA) has been widely utilized to grow lipophilic fungi belonging to the genus Malassezia. We developed a new artificial-sebum-containing...     

Comparison of Brilliant Green Agar and Hektoen Enteric Agar Media in the Isolation of Salmonellae from Food Products

Brilliant Green (BG) agar and Hektoen enteric (HE) agar media were compared for their efficiency in isolating salmonellae from various food products. Of the 11,226 food specimens examined, 1,662 (or 14.9%) yielded salmonellae. Of this number, 1,475 (88.7%) were recovered from BG agar and 1,315 (79.1%) were recovered from HE agar media. The results indicate that BG agar is more effective in isolating salmonellae from food products. A smaller subsidiary study showed HE agar to be more selective than BG agar. Four hundred ten specimens yielded 92 nonlactose-fermenting isolants other than salmonellae on BG agar and only 11 such isolants on HE agar.     

Dubos Oleic Acid Agar Medium in the Differentiation of Meningococci and Gonococci

Growth on Dubos oleic acid agar plates, incubated for 48 hr at 37 C in candle jars, provides a method for differentiating meningococci from gonococci. All of our 54 strains of meningococci, but none of the 49 strains of gonococci, grew on this medium.     

Use of Cross-Reactive Antibodies to Detect Members of the Potyviridae

In attempts to use cross-reacting antibodies for the broad-spectrum detection of potyviruses two broad-spectrum immunoreagents, the monoclonal antibody P-3-3H8 and antiserum Tu MV-314 raised against an isolate of peanut stripe virus and turnip mosaic virus, respectively, were examined for their ability to detect members of the Potyviridae in a simple indirect plate-trapped antigen (PTA) ELISA. Both immuno-reagents reacted strongly not only with isolate of 50 different virus species of the genus Potyvirus but also with several isolates of ryegrass mosaic virus, the type member of the genus Rymovirus A few members of the genus Potyvirus as well as agropyton mosaic and hordeum mosaic viruses, two other species of the genus, Rymovirus did not react with P-3-3H8 but only with TuMV-314 which showed the highest degree of cross-reactivity. In no case were positive reactions obtained with members of the genera Bymovirus and Ipomovirus. These two immunoreagents which appear to be directed to conserved epitopes gave good results when they were employed for detecting potyviruses in field samples from ornamental (Liliales) and leguminous plants. The potential and limitations of cross-reactive antibodies for the routine detection of potyviruses are discussed.     

Non-Newtonian Blood Flow in Left Coronary Arteries with Varying Stenosis: A Comparative Study

This paper presents Computational fluid dynamic (CFD) analysis of blood flow in three different 3-D models of left coronary artery (LCA). A comparative study of flow parameters (pressure distribution, velocity distribution and wall shear stress) in each of the models is done for a non-Newtonian (Carreau) as well as the Newtonian nature of blood viscosity over a complete cardiac cycle. The difference between these two types of behavior of blood is studied for both transient and steady states of flow. Additionally, flow parameters are compared for steady and transient boundary conditions considering blood as non-Newtonian fluid. The study shows that the highest wall shear stress (WSS), velocity and pressure are found in artery having stenosis in all the three branches of LCA. The use of Newtonian blood model is a good approximation for steady as well as transient blood flow boundary conditions if shear rate is above 100 s-1. However, the assumption of steady blood flow results in underestimating the values of flow parameters such as wall shear stress, pressure and velocity.     

Tolerance of Bacteria to High Concentrations of NaCl and Glycerol in the Growth Medium

When compared at similar levels of water activity, glycerol was more inhibitory than sodium chloride to relatively salt-tolerant bacteria and less inhibitory than salt to salt-sensitive species.     

A New Plating Medium for the Isolation of Enteric Pathogens: I. Hektoen Enteric Agar

A new agar plating medium for the isolation of enteric pathogens is described. This medium contains greater quantities of peptone to offset the inhibitory effects of bile salts. Additional carbohydrates and larger quantities of those previously used have also been incorporated into the medium to differentiate pathogens from some of the slow lactose fermenters. The use of an indicator system never used before in a differential plating medium opens new possibilities for improvement over traditional and newer selective media. Known strains from the various genera of Enterobacteriaceae have been tested for colonial differentiation as well as for possible inhibitory effects. The results show the medium to be highly selective for the shigellae as well as for other enteric pathogens.     

利用定量杂交法检测绵羊瘤胃纤维细菌的研究

实验利用通用细菌探针和3株纤维分解菌的特异性探针,初步建立起对瘤胃细菌进行检测的16SrRNA定量杂交的方法。试验将提取的总RNA按浓度系列稀释后与通用细菌探针进行杂交,检测结果所做的回归分析表明,杂交信号与尼龙膜上的所点RNA的量具有明显线性关系。同时对几份瘤胃样品进行3种纤维分解菌的初步定量检测,结果显示3种纤维分解菌的相对丰度与前人报道相似,表明该方法能够对瘤胃细菌进行定量分析,可在后续相关研究中使用。