One-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents

An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125I-labelled aryl compounds and SPECT radiotracers

A Study of the Small Rodents of Black Hawk County, Iowa (1961-1962)

Two-hundred and fifty-nine small rodents were collected in Black Hawk County, Iowa, from June 1961 to June 1962. Specimens were taken from 53 locations in the county. Specimens of the following species were collected: Spermophilus tridecemlineatus tridecemlineatus, Reithrodontomys megalotis dychei, Peromyscus maniculatus bairdii, Peromyscus leucopus noveboracensis, Microtus pennsylvanicus pennsylvanicus, Microtus ochrogaster ochrogaster, and Mus musculus. Perognathus flavescens perniger and Tamias striatus griseus were reported to have been obtained by other investigators, but neither was taken during this study period

The Role of Schwartz Measures in Human Tri-Color Vision

The human tri-color vision process may be characterized as follows: 1. A requirement of three scalar quantities to fully define a color (for example, intensity, hue, and purity), with 2. These scalar measures linear in the intensity of the incident light, allowing in general any specific color to be duplicated by an additive mixture of light from three standardized (basis) colors, 3. The exception being that the spectral colors are unique, in that they cannot be duplicated by any positive mixture of other colors. These characteristics strongly suggest that human color vision makes use of Schwartz measures in processing color data. This hypothesis is subject to test. In this brief paper, the results of this hypothesis are shown to be in good agreement with measured data

Processing strategies and recall performance for narrative passages and word lists of negative and neutral affective valence in depression

Depressed individuals have been found to exhibit memory deficits on tasks that require effortful processing. They have also been found to remember negative materials better than their nondepressed cohorts. While these findings are well-documented, there have been few studies designed to examine how and why these differences in recall occur. The present study examined prose passage and word list recall in depressed and nondepressed college students. Processing times and structure of recall were also examined to assist in determining how material was processed and remembered. Half of the passages and word lists utilized were of negative affective valence and half were of neutral affective valence. Subjects were 70 undergraduate students who completed the Beck Depression Inventory (BDI) and Geriatric Depression Scale (GDS) prior to selection and again at the time of participation to ensure stability of mood. Individuals scoring at or above 10 on the BDI and at or above 11 on the GDS during both screening and experimental phases were classified as depressed. Individuals scoring at or below four on the BDI and at or below four on the GDS during both screening and experimental phases were classified as nondepressed. Subjects read narrative passages and word lists from a computer screen. Rate of presentation was controlled by subjects and recorded in milliseconds by the computer. Oral recall was audiotaped immediately after each story or word list. Memory for each passage was expressed as the proportion of idea units recalled at each of three levels of importance. Prose passage recall analyses indicated that depressed subjects remembered more idea units from negative passages than neutral passages and exhibited superior recall to nondepressed subjects for negative word lists. Memory for each word list was expressed as the proportion of idea units recalled at each of three serial positions. Word list recall results revealed that nondepressed subjects recalled significantly more neutral words than negative words and demonstrated superior recall to depressed subjects for neutral word lists. Structure of recall and processing time did not vary between groups on either task despite differences in memory performance. Results indicated a mood congruent memory bias for both prose passages and word lists. The group exhibiting the mood congruent memory bias changed with task, however. The reason for the difference in the pattern of memory bias between the prose and word list recall tasks is not immediately obvious but may be the result of a differential degree of effortful processing required when processing word lists and prose passages. The implications of these findings in relation to models of cognitive processing in depression are discussed

Abnormalities of the ventilatory equivalent for carbon dioxide in patients with chronic heart failure

Introduction. The relation between minute ventilation (VE) and carbon dioxide production (VCO2) can be characterised by the instantaneous ratio of ventilation to carbon dioxide production, the ventilatory equivalent for CO2 (VEqCO2). We hypothesised that the time taken to achieve the lowest VEqCO2 (time to VEqCO2 nadir) may be a prognostic marker in patients with chronic heart failure (CHF). Methods. Patients and healthy controls underwent a symptom-limited, cardiopulmonary exercise test (CPET) on a treadmill to volitional exhaustion. Results. 423 patients with CHF (mean age 63±12 years; 80% males) and 78 healthy controls (62% males; age 61±11 years) were recruited. Time to VEqCO2 nadir was shorter in patients than controls (327±204 s versus 514±187 s; P=0.0001). Univariable predictors of all-cause mortality included peak oxygen uptake (X 2 =53.0), VEqCO2 nadir (X 2 =47.9), and time to VEqCO2 nadir (X 2 =24.0). In an adjusted Cox multivariable proportional hazards model, peak oxygen uptake (X 2 =16.7) and VEqCO2 nadir (X 2 =17.9) were the most significant independent predictors of all-cause mortality. Conclusion. The time to VEqCO2 nadir was shorter in patients with CHF than in normal subjects and was a predictor of subsequent mortality. © 2012 Lee Ingle et al

Probabilistic models to describe the dynamics of migrating microbial communities

In all but the most sterile environments bacteria will reside in fluid being transported through conduits and some of these will attach and grow as biofilms on the conduit walls. The concentration and diversity of bacteria in the fluid at the point of delivery will be a mix of those when it entered the conduit and those that have become entrained into the flow due to seeding from biofilms. Examples include fluids through conduits such as drinking water pipe networks, endotracheal tubes, catheters and ventilation systems. Here we present two probabilistic models to describe changes in the composition of bulk fluid microbial communities as they are transported through a conduit whilst exposed to biofilm communities. The first (discrete) model simulates absolute numbers of individual cells, whereas the other (continuous) model simulates the relative abundance of taxa in the bulk fluid. The discrete model is founded on a birth-death process whereby the community changes one individual at a time and the numbers of cells in the system can vary. The continuous model is a stochastic differential equation derived from the discrete model and can also accommodate changes in the carrying capacity of the bulk fluid. These models provide a novel Lagrangian framework to investigate and predict the dynamics of migrating microbial communities. In this paper we compare the two models, discuss their merits, possible applications and present simulation results in the context of drinking water distribution systems. Our results provide novel insight into the effects of stochastic dynamics on the composition of non-stationary microbial communities that are exposed to biofilms and provides a new avenue for modelling microbial dynamics in systems where fluids are being transported

An Infrared Study of the Circumstellar Material Associated with the Carbon Star R Sculptoris

The asymptotic giant branch (AGB) star R Sculptoris (R Scl) is one of the most extensively studied stars on the AGB. R Scl is a carbon star with a massive circumstellar shell ($M_{shell}\sim 7.3\times10^{-3}~M_{\odot}$) which is thought to have been produced during a thermal pulse event $\sim2200$ years ago. To study the thermal dust emission associated with its circumstellar material, observations were taken with the Faint Object InfraRed CAMera for the SOFIA Telescope (FORCAST) at 19.7, 25.2, 31.5, 34.8, and 37.1 $\mu$m. Maps of the infrared emission at these wavelengths were used to study the morphology and temperature structure of the spatially extended dust emission. Using the radiative transfer code DUSTY and fitting the spatial profile of the emission, we find that a geometrically thin dust shell cannot reproduce the observed spatially resolved emission. Instead, a second dust component in addition to the shell is needed to reproduce the observed emission. This component, which lies interior to the dust shell, traces the circumstellar envelope of R Scl. It is best fit by a density profile with $n \propto r^{\alpha}$ where $\alpha=0.75^{+0.45}_{-0.25}$ and dust mass of $M_d=9.0^{+2.3}_{-4.1}\times10^{-6}~M_{\odot}$. The strong departure from an $r^{-2}$ law indicates that the mass-loss rate of R Scl has not been constant. This result is consistent with a slow decline in the post-pulse mass-loss which has been inferred from observations of the molecular gas.Comment: 10 pages, 10 figures, accepted to Ap

Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems

UHV dynamic force and energy dissipation spectroscopy in non-contact atomic force microscopy were used to probe specific interactions with composite systems formed by encapsulating inorganic compounds inside single-walled carbon nanotubes. It is found that forces due to nano-scale van der Waals interaction can be made to decrease by combining an Ag core and a carbon nanotube shell in the Ag@SWNT system. This specific behaviour was attributed to a significantly different effective dielectric function compared to the individual constituents, evaluated using a simple core-shell optical model. Energy dissipation measurements showed that by filling dissipation increases, explained here by softening of C-C bonds resulting in a more deformable nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based on force and dissipation measurements. These findings have two different implications for potential applications: tuning the effective optical properties and tuning the interaction force for molecular absorption by appropriately choosing the filling with respect to the nanotube.Comment: 22 pages, 6 figure