Infrared photochemistry of ethylene clusters

Infrared irradiation of ethylene clusters formed in supersonic molecular beams, using a low power cw CO2 laser, results in the photodissociation of a large fraction of the van der Waals molecules. Under such conditions, infrared absorption intensity exhibits first-order power dependence and is readily detected as loss in molecular beam intensity. Intramolecular energy transfer rates, determined by measuring spectral linewidths, are shown to vary with the vibrational mode initially excited. Ethylene clusters containing one quantum of vibrational energy corresponding to the nun7 fundamental in the monomer (949 cm^–1) have a vibrationally predissociative lifetime of 0.33 psec. In comparison, the relaxation rate of ethylene-d4 clusters with one quantum of excitation corresponding to the nu12 (1078 cm^–1) mode of C2D4 is 0.7 psec

Neural Substrates of Reliability-Weighted Visual-Tactile Multisensory Integration

As sensory systems deteriorate in aging or disease, the brain must relearn the appropriate weights to assign each modality during multisensory integration. Using blood-oxygen level dependent functional magnetic resonance imaging of human subjects, we tested a model for the neural mechanisms of sensory weighting, termed “weighted connections.” This model holds that the connection weights between early and late areas vary depending on the reliability of the modality, independent of the level of early sensory cortex activity. When subjects detected viewed and felt touches to the hand, a network of brain areas was active, including visual areas in lateral occipital cortex, somatosensory areas in inferior parietal lobe, and multisensory areas in the intraparietal sulcus (IPS). In agreement with the weighted connection model, the connection weight measured with structural equation modeling between somatosensory cortex and IPS increased for somatosensory-reliable stimuli, and the connection weight between visual cortex and IPS increased for visual-reliable stimuli. This double dissociation of connection strengths was similar to the pattern of behavioral responses during incongruent multisensory stimulation, suggesting that weighted connections may be a neural mechanism for behavioral reliability weighting

Functional Group Bridge for Simultaneous Regression and Support Estimation

This article is motivated by studying multisensory effects on brain activities in intracranial electroencephalography (iEEG) experiments. Differential brain activities to multisensory stimulus presentations are zero in most regions and non-zero in some local regions, yielding locally sparse functions. Such studies are essentially a function-on-scalar regression problem, with interest being focused not only on estimating nonparametric functions but also on recovering the function supports. We propose a weighted group bridge approach for simultaneous function estimation and support recovery in function-on-scalar mixed effect models, while accounting for heterogeneity present in functional data. We use B-splines to transform sparsity of functions to its sparse vector counterpart of increasing dimension, and propose a fast non-convex optimization algorithm using nested alternative direction method of multipliers (ADMM) for estimation. Large sample properties are established. In particular, we show that the estimated coefficient functions are rate optimal in the minimax sense under the $L_2$ norm and resemble a phase transition phenomenon. For support estimation, we derive a convergence rate under the $L_{\infty}$ norm that leads to a sparsistency property under $\delta$-sparsity, and provide a simple sufficient regularity condition under which a strict sparsistency property is established. An adjusted extended Bayesian information criterion is proposed for parameter tuning. The developed method is illustrated through simulation and an application to a novel iEEG dataset to study multisensory integration. We integrate the proposed method into RAVE, an R package that gains increasing popularity in the iEEG community

An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification

The controversial Capitanian (Middle Permian, 262 Ma) extinction event is only known from equatorial latitudes, and consequently its global extent is poorly resolved. We demonstrate that there were two, severe extinctions amongst brachiopods in northern Boreal latitudes (Spitsbergen) in the Middle to Late Permian, separated by a recovery phase. New age dating of the Spitsbergen strata (belonging to the Kapp Starostin Formation), using strontium isotopes and d13C trends and comparison with better-dated sections in Greenland, suggests that the first crisis occurred in the Capitanian. This age assignment indicates that this Middle Permian extinction is manifested at higher latitudes. Redox proxies (pyrite framboids and trace metals) show that the Boreal crisis coincided with an intensification of oxygen depletion, implicating anoxia in the extinction scenario. The widespread and near-total loss of carbonates across the Boreal Realm also suggests a role for acidification in the crisis. The recovery interval saw the appearance of new brachiopod and bivalve taxa alongside survivors, and an increased mollusk dominance, resulting in an assemblage reminiscent of younger Mesozoic assemblages. The subsequent end-Permian mass extinction terminated this Late Permian radiation

Instruments of Empire: Colonial Elites and U.S. Governance in Early National Louisiana, 1803-1820

The United States confronted new problems of territorial expansion with the Louisiana Purchase, as it involved, for the first time, the transfer in sovereignty of a territory that contained a population who by birth, language and religion differed substantially from the inhabitants of the United States, but who had been guaranteed the rights of full citizens. A series of other colonial powers faced these same problems on the North American continent, notably the Spanish in Louisiana. As with those earlier powers, ultimately the United States pursued processes that both brought Louisiana government and law into line with its institutions, and allowed for continued local control. County and parish officeholders through their interactions with U.S. authorities prove especially useful for an examination of the processes that gradually integrated the Territory of Orleans into the United States. Neither a study of high political figures in Washington nor marginalized groups in Louisiana can accurately demonstrate how this process of accommodation worked. Local elites and U.S. officials served as the middlemen who oversaw the implementation of new policy and therefore were in a position to obstruct these policies if they so chose. Native-born Louisiana elites confronted significant challenges in dealing with a U.S. administration that in some areas chose to accommodate them, but in many others chose to implement policies through Anglo- American or foreign French newcomers to the territory. The change in sovereignty to the United States offered many individuals from local elites new pathways to power in the territorial legislature, and later in a stronger state legislature. Local governance played a central role in the success of U.S. sovereignty within Louisiana

Variation in home range size and patterns in adult female American crocodiles Crocodylus acutus

The American crocodile Crocodylus acutus is a threatened species that uses relatively deep, open-water habitats with low salinity. Adult female American crocodiles nest on sandy coastal beaches, islands or human-made berms, assist in the hatching process, and can travel long distances to nesting habitat. We satellite-tracked 15 adult female American crocodiles in 2 hydrologically distinct areas in Everglades National Park, Florida, USA, to quantify the home range sizes, test for intraspecific differences in home range and core area size and structure, and identify important crocodile high-use areas. Overall home ranges (95% kernel density estimate; KDE) for adult female crocodiles in South Florida ranged from 30.0 to 141.9 km2 (mean ± SD, 84.4 ± 32.3 km2), and core areas (50% KDE) ranged from 4.7 to 27.4 km2 (17.8 ± 7.3 km2). We identified patterns in home range and core area overlap, seasonally shifting patterns in core area use, and the Fox Lake complex as an important crocodile high-use area. As the population of American crocodiles continues to grow and expand into new areas, it is important for conservation managers to understand individual crocodile habitat-use patterns and spatial resource requirements

Neural Substrates of Sound–Touch Synesthesia after a Thalamic Lesion

Neural plasticity induced by stroke can mediate positive outcomes, such as recovery of function, but can also result in the formation of abnormal connections with negative consequences for perception and cognition. In three experiments using blood-oxygen level dependent (BOLD) functional magnetic resonance imaging, we examined the neural substrates of acquired auditory-tactile synesthesia, in which certain sounds can produce an intense somatosensory tingling sensation in a patient with a thalamic lesion. Compared with nine normal controls, the first experiment showed that the patient had a threefold greater BOLD response to sounds in the parietal operculum, the location of secondary somatosensory cortex. We hypothesized that this abnormal opercular activity might be the neural substrate of the patient\u27s synesthesia. Supporting this hypothesis, the second experiment demonstrated that sounds that produced no somatosensation did not evoke a BOLD response in the operculum, while sounds that produced strong somatosensations evoked large BOLD responses. These abnormal responses may have resulted from plasticity induced by the loss of somatosensory inputs. Consistent with this idea, in the third experiment, BOLD responses to somatosensory stimulation were significantly weaker in the patient\u27s operculum than in normal controls. These experiments demonstrate a double dissociation in the patient\u27s secondary somatosensory cortex (increased responses to auditory stimulation and decreased responses to somatosensory stimulation), and suggest both that stroke-induced plasticity can result in abnormal connections between sensory modalities that are normally separate, and that synesthesia can be caused by inappropriate connections between nearby cortical territories

Moving beyond misuse and diversion: the urgent need to consider the role of iatrogenic addiction in the current opioid epidemic.

An epidemic of drug overdose deaths has led to calls for programs and policies to limit misuse and diversion of opioid medications. Any parallel call to consider the risk of iatrogenic addiction when treating pain has been muted in comparison. We have moved beyond questions of nonmedical use, abuse, and diversion to highlight the role of prescription opioids in causing addiction even when prescribed and used appropriately. Unfortunately, current evidence is insufficient, and a rapid expansion of longitudinal research is urgently needed to guide clinicians in balancing the need for opioids with the risk of adverse consequences. Meanwhile, medical education should place greater emphasis on the abuse liability of prescription opioids, and providers should endeavor to attenuate risk when possible

Ultra-shallow-marine anoxia in an Early Triassic shallow-marine clastic ramp (Spitsbergen) and the suppression of benthic radiation

Lower Triassic marine strata in Spitsbergen accumulated on a mid-to-high latitude ramp in which high-energy foreshore and shoreface facies passed offshore into sheet sandstones of probable hyperpycnite origin. More distal facies include siltstones, shales and dolomitic limestones. Carbon isotope chemostratigraphy comparison allows improved age dating of the Boreal sections and shows a significant hiatus in the upper Spathian. Two major deepening events, in earliest Griesbachian and late Smithian time, are separated by shallowing-upwards trends that culminated in the Dienerian and Spathian substages. The redox record, revealed by changes in bioturbation, palaeoecology, pyrite framboid content and trace metal concentrations, shows anoxic phases alternating with intervals of better ventilation. Only Dienerian–early Smithian time witnessed persistent oxygenation that was sufficient to support a diverse benthic community. The most intensely anoxic, usually euxinic, conditions are best developed in offshore settings, but at times euxinia also developed in upper offshore settings where it is even recorded in hyperpycnite and storm-origin sandstone beds: an extraordinary facet of Spitsbergen's record. The euxinic phases do not track relative water depth changes. For example, the continuous shallowing upwards from the Griesbachian to lower Dienerian was witness to several euxinic phases separated by intervals of more oxic, bioturbated sediments. It is likely that the euxinia was controlled by climatic oscillations rather than intra-basinal factors. It remains to be seen if all the anoxic phases found in Spitsbergen are seen elsewhere, although the wide spread of anoxic facies in the Smithian/Spathian boundary interval is clearly a global event