A Threshold-Based Approach to Calorimetry in Helium Droplets: Measurement of Binding Energies of Water Clusters

Helium dropletbeam methods have emerged as a versatile technique that can be used to assemble a wide variety of atomic and molecular clusters. We have developed a method to measure the binding energies of clusters assembled in helium droplets by determining the minimum droplet sizes required to assemble and detect selected clusters in the spectrum of the dopeddropletbeam. The differences in the droplet sizes required between the various multimers are then used to estimate the incremental binding energies. We have applied this method to measure the binding energies of cyclic waterclusters from the dimer to the tetramer. We obtain measured values of D0 that are in agreement with theoretical estimates to within ∼20%. Our results suggest that this threshold-based approach should be generally applicable using either mass spectrometry or optical spectroscopy techniques for detection, provided that the clusters selected for study are at least as strongly bound as those of water, and that a peak in the overall spectrum of the beam corresponding only to the cluster chosen (at least in the vicinity of the threshold) can be located

With my mouth

This collection of short stories explores many possible forms and uses of the genre of science fiction, ranging from explorations of the impact of science upon philosophical and religious issues and vice versa, to speculations about possible future understandings of identity rooted in ethnicity, culture, and even species. These stories range in setting and mood from a bizarre but humorous alternate history (á la Dickens) to a Buddhist-inhabited far-future dystopia, and employ a wide range of techniques and strategies. While these stories tend to use traditional (realist) narrative techniques, they use them strategically to immerse readers in performative examinations of many issues which are often addressed through formal experimentation--sometimes from perspectives that address these issues more forcefully than a formal experiment might succeed in doing. While thereby seeking to literally "hack" (in both senses of the word) readerly assumptions, these stories also argue performatively for a much wider range of imaginative possibilities and suitable topics of direct examination for SF than is often utilized by its practitioners or even acknowledged possible by its readers, both those of the street and those of the academy

Functional Nanoparticles in Thin Films as Sensing Media

The combination of unique properties offered by materials on the nanoscale with the increased role of surface chemistry in nanostructured solids makes core-shell nanoparticles extremely attractive for application to smart thin-film coatings. Sensing properties of nanoparticle-based thin films were studied in several systems containing organic-coated semiconductor and metallic particles. In semiconductors, the interaction of organic shell and/or thin-film matrix with the environment results in changes in the nanoparticle\u27s surface states, altering the optical properties of the thin film. Measuring the electrical properties of thin films composed of metallic cores with hydrocarbon shells offers another mechanism to monitor the local environment through the swelling of the hydrocarbons in the presence of external compounds. These mechanisms and their potential application to novel sensors will be discussed

Dysfunction of cortical GABAergic neurons leads to sensory hyper-reactivity in a Shank3 mouse model of ASD.

Hyper-reactivity to sensory input is a common and debilitating symptom in individuals with autism spectrum disorders (ASD), but the neural basis underlying sensory abnormality is not completely understood. Here we examined the neural representations of sensory perception in the neocortex of a Shank3B-/- mouse model of ASD. Male and female Shank3B-/- mice were more sensitive to relatively weak tactile stimulation in a vibrissa motion detection task. In vivo population calcium imaging in vibrissa primary somatosensory cortex (vS1) revealed increased spontaneous and stimulus-evoked firing in pyramidal neurons but reduced activity in interneurons. Preferential deletion of Shank3 in vS1 inhibitory interneurons led to pyramidal neuron hyperactivity and increased stimulus sensitivity in the vibrissa motion detection task. These findings provide evidence that cortical GABAergic interneuron dysfunction plays a key role in sensory hyper-reactivity in a Shank3 mouse model of ASD and identify a potential cellular target for exploring therapeutic interventions

Worry Is Good for Breast Cancer Screening: A Study of Female Relatives from the Ontario Site of the Breast Cancer Family Registry

Background. Few prospective studies have examined associations between breast cancer worry and screening behaviours in women with elevated breast cancer risks based on family history. Methods. This study included 901 high familial risk women, aged 23–71 years, from the Ontario site of the Breast Cancer Family Registry. Self-reported breast screening behaviours at year-one followup were compared between women at low (N=305), medium (N=433), and high (N=163) levels of baseline breast cancer worry using logistic regression. Nonlinear relationships were assessed using likelihood ratio tests. Results. A significant non-linear inverted “U” relationship was observed between breast cancer worry and mammography screening (P=0.034) for all women, where women at either low or high worry levels were less likely than those at medium to have a screening mammogram. A similar significant non-linear inverted “U” relationship was also found among all women and women at low familial risk for worry and screening clinical breast examinations (CBEs). Conclusions. Medium levels of cancer worries predicted higher rates of screening mammography and CBE among high-risk women

New insights into the classification and nomenclature of cortical GABAergic interneurons.

A systematic classification and accepted nomenclature of neuron types is much needed but is currently lacking. This article describes a possible taxonomical solution for classifying GABAergic interneurons of the cerebral cortex based on a novel, web-based interactive system that allows experts to classify neurons with pre-determined criteria. Using Bayesian analysis and clustering algorithms on the resulting data, we investigated the suitability of several anatomical terms and neuron names for cortical GABAergic interneurons. Moreover, we show that supervised classification models could automatically categorize interneurons in agreement with experts' assignments. These results demonstrate a practical and objective approach to the naming, characterization and classification of neurons based on community consensus