Using Bayesian variable selection methods to choose style factors in global stock return models

This paper applies Bayesian variable selection methods from the statistics literature to give guidance in the decision to include/omit factors in a global (linear factor) stock return model. Once one has accounted for country and sector, it is possible to see which style or styles best explains current asset returns. This study does not find compelling evidence for global styles as useful explanatory factors, once country and sector have been accounted for

No-till Forage Establishment in Alaska

We assessed the effectiveness of no-till forage establishment at six Alaska locations: Anchor Point, Sterling, Point MacKenzie, Palmer, Delta Junction, and Fairbanks. Directly seeding grass into established grass stands generally did not improve forage yields or quality. Seeding rate had little effect on establishment of newly seeded forages in no-till. Grass yields were depressed when companion crop yields were high, and they typically did not recover in subsequent years. Red clover established well, producing high yields of good quality forage under no-till at Point MacKenzie, but established poorly at Anchor Point and Delta Junction. These results indicated that no-till seeding of most forage crops into declining grass stands is not likely to be successful in Alaska with current available technology

Desynchronization of pathological low-frequency brain activity by the hypnotic drug zolpidem.

Reports of the beneficial effects of the hypnotic imidazopyridine, zolpidem, described in persistent vegetative state^1, 2^ have been replicated recently in brain-injured and cognitively impaired patients^3-7^. Previous single photon emission computed tomography (SPECT) studies have suggested that sub-sedative doses of zolpidem increased regional cerebral perfusion in affected areas^5, 8^, implying enhanced neuronal metabolic activity; which has led to speculation that zolpidem 'reawakens' functionally dormant cortex. However, a neuronal mechanism by which this hypnotic drug affords benefits to brain injured patients has yet to be demonstrated. Here, we report the action of sub-sedative doses of zolpidem on neuronal network oscillatory activity in human brain, measured using pharmaco-magnetoencephalography (pharmaco-MEG). Study participant JP suffered a stroke in 1996, causing major damage to the left hemisphere that impaired aspects of both motor and cognitive function. Pharmaco-MEG analyses revealed robust and persistent pathological theta (4-10Hz) and beta (15-30Hz) oscillations within the lesion penumbra and surrounding cortex. Administration of zolpidem (5mg) reduced the power of pathological theta and beta oscillations in all regions of the lesioned hemisphere. This desynchronizing effect correlated well with zolpidem uptake (occurring approximately 40 minutes after acute administration) and was coincident with marked improvements in cognitive and motor function. Control experiments revealed no effect of placebo, while a structurally unrelated hypnotic, zopiclone, administered at a comparable dose (3.5mg) elicited widespread increases in cortical oscillatory power in the beta (15-30Hz) band without functional improvement. These results suggest that in JP, specific motor and cognitive impairments are related to increased low-frequency oscillatory neuronal network activity. Zolpidem is unique amongst hypnotic drugs in its ability to desynchronize such pathological low-frequency activity, thereby restoring cognitive function

The Prehistoric Sites at Choke Canyon Reservoir, Southern Texas: Results of Phase II Archaeological Investigations

Reported in this volume are the results of archaeological investigations at 72 prehistoric sites located in the basin of Choke Canyon Reservoir on the Frio River in Live Oak and McMullen Counties, southern Texas. The sites investigated in this study will be affected in one way or another by a lake formed after construction of Choke Canyon Dam, a project of the United States Bureau of Reclamation CUSBR). The research was sponsored by the USBR as the second and final phase of a two-stage program of archaeological investigations designed to mitigate damage or destruction of cultural resources resulting from dam construction and subsequent long-term inundation of a large area of the Frio River valley. Methods used to study Choke Canyon\u27s prehistoric sites during the Phase II investigation were various types of subsurface excavations, documentation of surface features and characteristics, and collection of artifacts from site surfaces. The people who inhabited the Choke Canyon region in prehistoric times, representing an approximate span of 10,000 years, existed as mobile hunter/gatherer bands. They subsisted by tapping virtually every conceivable source of edible natural food. A full spectrum of animals, from lowly field mice and lizards up to bison and deer, was exploited by various techniques of hunting, trapping, and catching. Large land snails and mussels were sources of meat food that Choke Canyon\u27s prehistoric people could easily gather. Gar, drum, and turtles were taken from local creeks, sloughs, and the river, perhaps using spears, nets, or weirs. Analysis of vertebrate faunal remains, results of which are presented herein, rather conclusively demonstrates that Late Prehistoric people exploited big game species more commonly than did their Archaic period predecessors. Floral products must also have comprised a substantial portion of the foods consumed by Choke Canyon\u27s prehistoric inhabitants. Direct evidence of plant food utilization is nonexistent on the sites. However, the very common occurrence of sandstone manes and metates implies heavy reliance on seeds, nuts, or beans. Also, the tremendous amount of burned rock that accumulated in Archaic components at many sites, often found as very carefully constructed hearth features, suggests that baking or roasting activities were extremely common. Roots, tubers, stalks, and other edible plant parts may have been what was being prepared in these facilities. Diagnostic artifacts recovered from prehistoric sites at Choke Canyon during the various phases of archaeological investigation clearly indicate that the general vicinity witnessed aboriginal activity from Paleo-Indian times up through the early Historic period. Evidence of Paleo-Indian people is limited to surface finds along the valley margin and on high, ancient terrace formations down in the river valley. No in situ subsurface Paleo-Indian components have yet been isolated at Choke Canyon. Where previously the earliest subsurface component known at Choke Canyon dated to the Middle Archaic period (ca. 3400 B.C. to 2400 B.C.), the Phase II excavations led to discovery of an Early Archaic component dating to the period from 5000 B.C. xi to 4000 B.C. While recognizable Paleo-Indian, Early Archaic, and Middle Archaic components are relatively scarce, the Late Archaic and Late Prehistoric periods are amply represented in the prehistoric sites at Choke Canyon. Phase II investigations also produced the first clear indication of an aboriginal component containing evidence of contact with Anglo-Europeans in early historic times. The bulk of cultural, paleobotanical, and vertebrate faunal data representing the prehistory of Choke Canyon indicates that floral and faunal communities and the general climatic regime remained essentially unchanged from at least 4000 B.C. up to the period in historic times when certain livestock and land management practices led to a drastic expansion of brush communities and severe erosion of formerly stable land surfaces

Does Epileptiform Activity Represent a Failure of Neuromodulation to Control Central Pattern Generator-Like Neocortical Behavior?

Rhythmic motor patterns in invertebrates are often driven by specialized "central pattern generators" (CPGs), containing small numbers of neurons, which are likely to be "identifiable" in one individual compared with another. The dynamics of any particular CPG lies under the control of modulatory substances, amines, or peptides, entering the CPG from outside it, or released by internal constituent neurons; consequently, a particular CPG can generate a given rhythm at different frequencies and amplitudes, and perhaps even generate a repertoire of distinctive patterns. The mechanisms exploited by neuromodulators in this respect are manifold: Intrinsic conductances (e.g., calcium, potassium channels), conductance state of postsynaptic receptors, degree of plasticity, and magnitude and kinetics of transmitter release can all be affected. The CPG concept has been generalized to vertebrate motor pattern generating circuits (e.g., for locomotion), which may contain large numbers of neurons - a construct that is sensible, if there is enough redundancy: that is, the large number of neurons consists of only a small number of classes, and the cells within any one class act stereotypically. Here we suggest that CPG and modulator ideas may also help to understand cortical oscillations, normal ones, and particularly transition to epileptiform pathology. Furthermore, in the case illustrated, the mechanism of the transition appears to be an exaggerated form of a normal modulatory action used to influence sensory processing

Excavations at 41LK67 a Prehistoric Site in the Choke Canyon Reservior, South Texas

In 1977-1978 excavations were conducted at 41 LK 67 in Live Oak County, south Texas, by the Center for Archaeological Research, The University of Texas at San Antonio. The investigation of this prehistoric archaeological site was part of an extensive program of reconnaissance and excavation necessitated by the construction of the Choke Canyon Reservoir on the Frio River by the Bureau of Reclamation. The site is situated in shallow colluvial deposits capping an old terrace remnant of the Frio River. The excavations involved 193 m2 in three separate areas and revealed Late Prehistoric and Late Archaic components. Recognizably older artifacts (including patinated chert flakes) from the surface and from excavations may represent older disturbed components or artifacts collected prehistorically from nearby sites. Radiocarbon dates, with medians ranging from 1590 to 660 B.C. (MASCA correction) are available only from the Late Archaic component. The principal kinds of debris recovered from the excavations are fire-cracked rock, cores and chipping debris, shells of snails and freshwater mussels, plainware potsherds, and chipped stone tools. Mussel shell was surprisingly abundant; more than 9000 specimens, including 3000 specimens identified taxonomically, were recovered. Fish otoliths were the only animal bones preserved, except for a few recent, intrusive elements. Debris frequencies from the two larger excavation blocks (Areas A and B) were factor analyzed. In most cases the analysis showed the strongest covariation occurring among different classes of chipping debris. For Area C factor analysis indicated that the strongest spatial patterning occurred in the upper part of the deposits. Unfortunately, the analysis was not particularly successful in defining activity sets. The small collection of chipped stone tools was examined microscopically. Two tool classes in particular, distally beveled tools (gouges) and quadrilateral bifaces (beveled knives) seem to represent more functionally specific tool forms, but other hafted bifaces (projectile points) show a wide range of use wear mostly unrelated to projectile use

Designing antibiotic cycling strategies by determining and understanding local adaptive landscapes

The evolution of antibiotic resistance among bacteria threatens our continued ability to treat infectious diseases. The need for sustainable strategies to cure bacterial infections has never been greater. So far, all attempts to restore susceptibility after resistance has arisen have been unsuccessful, including restrictions on prescribing [1] and antibiotic cycling [2,3]. Part of the problem may be that those efforts have implemented different classes of unrelated antibiotics, and relied on removal of resistance by random loss of resistance genes from bacterial populations (drift). Here, we show that alternating structurally similar antibiotics can restore susceptibility to antibiotics after resistance has evolved. We found that the resistance phenotypes conferred by variant alleles of the resistance gene encoding the TEM {\beta}-lactamase (blaTEM) varied greatly among 15 different {\beta}-lactam antibiotics. We captured those differences by characterizing complete adaptive landscapes for the resistance alleles blaTEM-50 and blaTEM-85, each of which differs from its ancestor blaTEM-1 by four mutations. We identified pathways through those landscapes where selection for increased resistance moved in a repeating cycle among a limited set of alleles as antibiotics were alternated. Our results showed that susceptibility to antibiotics can be sustainably renewed by cycling structurally similar antibiotics. We anticipate that these results may provide a conceptual framework for managing antibiotic resistance. This approach may also guide sustainable cycling of the drugs used to treat malaria and HIV

Analysis and Modeling of Ground Operations at Hub Airports

Building simple and accurate models of hub airports can considerably help one understand airport dynamics, and may provide quantitative estimates of operational airport improvements. In this paper, three models are proposed to capture the dynamics of busy hub airport operations. Two simple queuing models are introduced to capture the taxi-out and taxi-in processes. An integer programming model aimed at representing airline decision-making attempts to capture the dynamics of the aircraft turnaround process. These models can be applied for predictive purposes. They may also be used to evaluate control strategies for improving overall airport efficiency.This research was supported in part by Honeywell, by an MIT teaching fellowship, and by NASA under grant NAG 2-1128 and through the National Center of Excellence for Aviation Operations Research (NEXTOR)

Early respiratory viral infections in infants with cystic fibrosis

This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Background Viral infections contribute to morbidity in cystic fibrosis (CF), but the impact of respiratory viruses on the development of airway disease is poorly understood. Methods Infants with CF identified by newborn screening were enrolled prior to 4 months of age to participate in a prospective observational study at 4 centers. Clinical data were collected at clinic visits and weekly phone calls. Multiplex PCR assays were performed on nasopharyngeal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent bronchoscopy with bronchoalveolar lavage (BAL) and a subset underwent pulmonary function testing. We present findings through 8.5 months of life. Results Seventy infants were enrolled, mean age 3.1 ± 0.8 months. Rhinovirus was the most prevalent virus (66%), followed by parainfluenza (19%), and coronavirus (16%). Participants had a median of 1.5 viral positive swabs (range 0–10). Past viral infection was associated with elevated neutrophil concentrations and bacterial isolates in BAL fluid, including recovery of classic CF bacterial pathogens. When antibiotics were prescribed for respiratory-related indications, viruses were identified in 52% of those instances. Conclusions Early viral infections were associated with greater neutrophilic inflammation and bacterial pathogens. Early viral infections appear to contribute to initiation of lower airway inflammation in infants with CF. Antibiotics were commonly prescribed in the setting of a viral infection. Future investigations examining longitudinal relationships between viral infections, airway microbiome, and antibiotic use will allow us to elucidate the interplay between these factors in young children with CF

Assessment of Swedish snus for tobacco harm reduction: an epidemiological modelling study

BACKGROUND: Swedish snus is a smokeless tobacco product that has been suggested as a tobacco harm reduction product. Our aim was to assess the potential population health effects of snus. METHODS: We assessed the potential population health effects of snus in Australia with multistate life tables to estimate the difference in health-adjusted life expectancy between people who have never been smokers and various trajectories of tobacco use, including switching from smoking to snus use; and the potential for net population-level harm given different rates of snus uptake by current smokers, ex-smokers, and people who have never smoked. FINDINGS: There was little difference in health-adjusted life expectancy between smokers who quit all tobacco and smokers who switch to snus (difference of 0.1-0.3 years for men and 0.1-0.4 years for women). For net harm to occur, 14-25 ex-smokers would have to start using snus to offset the health gain from every smoker who switched to snus rather than continuing to smoke. Likewise, 14-25 people who have never smoked would need to start using snus to offset the health gain from every new tobacco user who used snus rather than smoking. INTERPRETATION: Current smokers who switch to using snus rather than continuing to smoke can realise substantial health gains. Snus could produce a net benefit to health at the population level if it is adopted in sufficient numbers by inveterate smokers. Relaxing current restrictions on the sale of snus is more likely to produce a net benefit than harm, with the size of the benefit dependent on how many inveterate smokers switch to snus