1,105 research outputs found
Development of anlytical techniques for hydrocarbons in mineral aggregates quarterly status report no. 4, jul. - sep. 1964
Chemical analysis of rock and meteorite samples for hydrocarbon conten
The effects of climate change on the phenology of plants and insects of Massachusetts
Thesis (Ph.D.)--Boston UniversityPhenology, the timing of biological events, is a common metric used to measure the effect of climate change on ecosystems. Leaf out timing is a particularly important indicator because it is highly sensitive to temperature, represents a critical transition point of annual seasonality, and is an important driver of ecosystem processes. The mechanisms behind this have recently gained attention, and I wrote a literature review on the topic that surveyed what is known and identified topics that require further investigation (Chapter 1). In the next chapter, I focused on specific aspects of leaf out phenology using observation and experimentation. To examine the effects of climate change on leafing, I utilized historical records (1852-1860) and made observations (2009-2012) of leaf out in Concord, Massachusetts (Chapter 2). Leafing is now an average of 19 days earlier than in the past. Recently published studies suggest that the continued advance of leaf out is uncertain; with continued warming, unmet chilling requirements may lead to delays in leafing. To address this, I experimentally investigated chilling requirements of local species (Chapter 2). I compared the sensitivity of leaf out to spring temperature as measured by field observations, remotely sensed data, and experimental warming to determine differences resulting from these methods (Chapter 3). Earlier leaf out with warmer temperatures was found with all methods; however, leafing was more than twice as sensitive to temperature in the field study as under experimental warming, with remote sensing intermediate.
To better understand the effects of climate change on ecosystems, we must obtain reliable information about multiple trophic levels. I examined the effects of temperature on the flight dates of ten species of Massachusetts butterflies (1895-2009) using both museum specimen records and citizen science data: the response of these species is similar to that of flowering and bee flight times and significantly greater than changes in bird arrival (Chapter 4). As long as investigators are aware of the limitations of each data source, historical data, remote sensing, experiments, and citizen science data are all effective tools for studying the effect of climate change on phenology
Improving Link Reliability through Network Coding in Cooperative Cellular Networks
The paper proposes a XOR-based network coded cooperation protocol for the uplink transmission of relay assisted cellular networks and an algorithm for selection and assignment of the relay nodes. The performances of the cooperation protocol are expressed in terms of network decoder outage probability and Block Error Rate of the cooperating users. These performance indicators are analyzed theoretically and by computer simulations. The relay nodes assignment is based on the optimization, according to several criteria, of the graph that describes the cooperation cluster formed after an initial selection of the relay nodes. The graph optimization is performed using Genetic Algorithms adapted to the topology of the cooperation cluster and the optimization criteria considered
Projection neurons in lamina III of the rat spinal cord are selectively innervated by local dynorphin-containing excitatory neurons
Large projection neurons in lamina III of the rat spinal cord that express the neurokinin 1 receptor are densely innervated by peptidergic primary afferent nociceptors and more sparsely by low-threshold myelinated afferents. However, we know little about their input from other glutamatergic neurons. Here we show that these cells receive numerous contacts from nonprimary boutons that express the vesicular glutamate transporter 2 (VGLUT2), and form asymmetrical synapses on their dendrites and cell bodies. These synapses are significantly smaller than those formed by peptidergic afferents, but provide a substantial proportion of the glutamatergic synapses that the cells receive (over a third of those in laminae I–II and half of those in deeper laminae). Surprisingly, although the dynorphin precursor preprodynorphin (PPD) was only present in 4–7% of VGLUT2 boutons in laminae I–IV, it was found in 58% of the VGLUT2 boutons that contacted these cells. This indicates a highly selective targeting of the lamina III projection cells by glutamatergic neurons that express PPD, and these are likely to correspond to local neurons (interneurons and possibly projection cells). Since many PPD-expressing dorsal horn neurons respond to noxious stimulation, this suggests that the lamina III projection cells receive powerful monosynaptic and polysynaptic nociceptive input. Excitatory interneurons in the dorsal horn have been shown to possess IA currents, which limit their excitability and can underlie a form of activity-dependent intrinsic plasticity. It is therefore likely that polysynaptic inputs to the lamina III projection neurons are recruited during the development of chronic pain states
Reference values for spirometry and their use in test interpretation: A Position Statement from the Australian and New Zealand Society of Respiratory Science
Traditionally, spirometry testing tended to be confined to the realm of hospital-based laboratories but is now performed in a variety of health care settings. Regardless of the setting in which the test is conducted, the fundamental basis of spirometry is that the test is both performed and interpreted according to the international standards. The purpose of this Australian and New Zealand Society of Respiratory Science (ANZSRS) statement is to provide the background and recommendations for the interpretation of spirometry results in clinical practice. This includes the benchmarking of an individual's results to population reference data, as well as providing the platform for a statistically and conceptually based approach to the interpretation of spirometry results. Given the many limitations of older reference equations, it is imperative that the most up-to-date and relevant reference equations are used for test interpretation. Given this, the ANZSRS recommends the adoption of the Global Lung Function Initiative (GLI) 2012 spirometry reference values throughout Australia and New Zealand. The ANZSRS also recommends that interpretation of spirometry results is based on the lower limit of normal from the reference values and the use of Z-scores where available
Mechanisms in bradykinin stimulated arachidonate release and synthesis of prostaglandin and platelet activating factor
Regulatory mechanisms in bradykinin (BK) activated release of arachidonate (ARA) and synthesis of prostaglandin (PG) and platelet activating factor (PAF) were studied in bovine pulmonary artery endothelial cells (BPAEC). A role for GTP binding protein (G-protein) in the binding of BK to the cells was determined. Guanosine 5-O- (thiotriphosphate), (GTPĎ„S), lowered the binding affinity for BK and increased the Kd for the binding from 0.45 to 1.99 nM. The Bmax remained unaltered at 2.25 Ă— 10-11 mole. Exposure of the cells to aluminium fluoride also reduced the affinity for BK. Bradykinin-induced release of ARA proved pertussis toxin (PTX) sensitive, with a maximum sensitivity at 10 ug/ml PTX. GTPĎ„S at 100 ÎĽM increased the release of arachidonate. The effect of GTPĎ„S and BK was additive at suboptimal doses of BK up to 0.5 nM but never exceeded the levels of maximal BK stimulation at 50 nM. PTX also inhibited the release of ARA induced by the calcium ionophore, A23187. Phorbol 12-myristate 13-acetate or more commonly known as tetradecanoyl phorbol acetate (TPA) itself had little effect on release by the intact cells. However, at 100 nM it augmented the BK activated release. This was downregulated by overnight exposure to TPA and correlated with down-regulation of protein kinase C (PKC) activity. The down-regulation only affected the augmentation of ARA release by TPA but not the original BK activated release. TPA displayed a similar, but more potent amplification of PAF synthesis in response to both BK or the calcium ionophore A23187. These results taken together point to the participation of G-protein in the binding of BK to BPAEC and its activation of ARA release. Possibly two types of G-protein are involved, one associated with the receptor, the other activated by Ca2+ and perhaps associated with phospholipase A2 (PLA2). Our results further suggest that a separate route of activation, probably also PLA2 related, takes place through a PKC catalysed phosphorylation
Modern Foraminifera from a depth transect offshore Brunei Darussalam: diversity, sedimentation rate and preservation pathways.
An Analysis of 1974 Striped Bass spawning success in the Potomac Estuary.
ABSTRACT: The Potomac River Fisheries Program is concerned with the longterm effects of power plant ichthyoplankton entrainment on striped bass(hforone smatilis) recruitment. Since striped bass population fluctuations are determined strongly by environmental conditions during spawning and early development, assessment of power plant-induced ichthyoplankton mortalities must consider the mechanisms controlling spawning success. Ichthyoplankton distributions for 1974, spawning population abundance and fecundity, and environmental conditions were considered for analysis. Loss of the early part of the spawn (including the peak) accounted for the highest mortalities among ichthyoplankton. This was due to the proximity of these distributions to the salt wedge where transport into regions un!ivorable to survival seems to have occurred. The later, successful portion of the spawn occurred further upstream, in fresh tidal portions of the river. The sequence of events Ieading to an assessment of factors affecting ichthyoplankton surnnl are evaluated. Due to high early mortalities in ichthyoplankton, 1974 spawning success was low, and a poor yearclass is projected
Combined distributed turbo coding and space frequency block coding techniques
The distributed space-time (frequency) coding and distributed channel turbo coding used independently represent two cooperative techniques that can provide increased throughput and spectral efficiency at an imposed maximum Bit Error Rate (BER) and delay required from the new generation of cellular networks. This paper proposes two cooperative algorithms that employ jointly the two types of techniques, analyzes their BER and spectral efficiency performances versus the qualities of the channels involved, and presents some conclusions regarding the adaptive employment of these algorithms. © 2010 V. Bota et al.FP7/ICT/2007/21547
Acoustic Communication at the Water's Edge: Evolutionary Insights from a Mudskipper
Coupled behavioural observations and acoustical recordings of aggressive dyadic contests showed that the mudskipper Periophthalmodon septemradiatus communicates acoustically while out of water. An analysis of intraspecific variability showed that specific acoustic components may act as tags for individual recognition, further supporting the sounds' communicative value. A correlative analysis amongst acoustical properties and video-acoustical recordings in slow-motion supported first hypotheses on the emission mechanism. Acoustic transmission through the wet exposed substrate was also discussed. These observations were used to support an “exaptation hypothesis”, i.e. the maintenance of key adaptations during the first stages of water-to-land vertebrate eco-evolutionary transitions (based on eco-evolutionary and palaeontological considerations), through a comparative bioacoustic analysis of aquatic and semiterrestrial gobiid taxa. In fact, a remarkable similarity was found between mudskipper vocalisations and those emitted by gobioids and other soniferous benthonic fishes
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