1,787 research outputs found
When Alston met Brandom: Defining assertion
In this paper I give a definition of assertion that develops William P. Alstonâs account. Alstonâs account of assertion combines a responsibility condition R, which captures the appropriate socio-normative status that one undertakes in asserting something, with an explicit presentation condition, such that the speech act in some way presents the content of what is being asserted. I develop Alstonâs account of explicit presentation and add a Brandomian responsibility condition. I then argue that this produces an attractive position on the nature of assertion
An analysis of space power system masses
Various space electrical power system masses are analyzed with particular emphasis on the power management and distribution (PMAD) portion. The electrical power system (EPS) is divided into functional blocks: source, interconnection, storage, transmission, distribution, system control and load. The PMAD subsystem is defined as all the blocks between the source, storage and load, plus the power conditioning equipment required for the source, storage and load. The EPS mass of a wide range of spacecraft is then classified as source, storage or PMAD and tabulated in a database. The intent of the database is to serve as a reference source for PMAD masses of existing and in-design spacecraft. The PMAD masses in the database range from 40 kg/kW to 183 kg/kW across the spacecraft systems studied. Factors influencing the power system mass are identified. These include the total spacecraft power requirements, total amount of load capacity and physical size of the spacecraft. It is found that a new utility class of power systems, represented by Space Station Freedom, is evolving
Foreign bank entry - experience, implications for developing countries, and agenda for further research
In recent years, foreign bank participation has increased tremendously in several developing countries. In Argentina, Chile, the Czech Republic, Hungary and Poland, for example, more than fifty percent of banking assets are now in foreign-controlled banks. In Asia, Africa, The Middle East, and the former Soviet Union, the rate of entry by foreign banks has been slower, but the trend is similar. Although the number of countries welcoming foreign banks is growing, many questions about foreign bank entry are still being debated, including: 1) What draws foreign banks to a country? 2) Which banks expand abroad? 3) What do foreign banks do once they arrive? 4) How does the mode of a bank's entry - for example, as a branch of its parent, or as an independent subsidiary company - affect its behavior? The authors summarize current knowledge on these issues. In addition, since the existing literature focuses heavily on industrial countries, they put forth an agenda for further study of the effects of foreign bank entry in developing countries.Financial Intermediation,Banks&Banking Reform,Payment Systems&Infrastructure,Financial Crisis Management&Restructuring,Banking Law,Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Banking Law,Municipal Financial Management
Ca2+ -permeable AMPA receptors and their auxiliary subunits in synaptic plasticity and disease
AMPA receptors are tetrameric glutamateâgated ion channels that mediate a majority of fast excitatory neurotransmission in the brain. They exist as calciumâimpermeable (CIâ) and calciumâpermeable (CPâ) subtypes, the latter of which lacks the GluA2 subunit. CPâAMPARs display an array of distinctive biophysical and pharmacological properties that allow them to be functionally identified. This has revealed that they play crucial roles in diverse forms of central synaptic plasticity. Here we summarise the functional hallmarks of CPâAMPARs and describe how these are modified by the presence of auxiliary subunits that have emerged as pivotal regulators of AMPARs. A lasting change in the prevalence of GluA2âcontaining AMPARs, and hence in the fraction of CPâAMPARs, is a feature in many maladaptive forms of synaptic plasticity and neurological disorders. These include modifications of glutamatergic transmission induced by inflammatory pain, fear conditioning, cocaine exposure, and anoxiaâinduced damage in neurons and glia. Furthermore, defective RNA editing of GluA2 can cause altered expression of CPâAMPARs and is implicated in motor neuron damage (amyotrophic lateral sclerosis) and the proliferation of cells in malignant gliomas. A number of the players involved in CPâAMPAR regulation have been identified, providing useful insight into interventions that may prevent the aberrant CPâAMPAR expression. Furthermore, recent molecular and pharmacological developments, particularly the discovery of TARP subtypeâselective drugs, offer the exciting potential to modify some of the harmful effects of increased CPâAMPAR prevalence in a brain regionâspecific manner
Bank lending to small businesses in Latin America : does Bank origin matter?
In recent years foreign bank participation has increased tremendously in Latin America. Some observers argue that foreign bank entry will benefit Latin American banking systems by reducing the volatility of loans and deposits and increasing efficiency. Others are concerned that foreign banks might choose to extend credit only to certain customers, leaving some sectors-such as small businesses-unserved. The authors examine this issue. Using bank-level data for Argentina, Chile, Colombia, and Peru during the mid-1990s, they empirically investigate whether bank origin affects the share and growth rate of bank lending to small businesses. They find that although foreign banks generally lent less to small businesses (as share of total lending) than private domestic banks, the difference is due primarily to the behavior of small foreign banks. The difference was considerably smaller for large and medium-sized banks. And in Chile and Colombia, large foreign banks might actually lend slightly more (as share of total lending) than large domestic banks.Financial Intermediation,Banks&Banking Reform,Financial Crisis Management&Restructuring,Payment Systems&Infrastructure,Economic Theory&Research,Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Economic Theory&Research,Banking Law
TARP Îł-2 is required for inflammation-associated AMPA receptor plasticity within lamina II of the spinal cord dorsal horn
In the brain, transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) critically influence the distribution, gating, and pharmacology of AMPARs, but the contribution of these auxiliary subunits to AMPAR-mediated signaling in the spinal cord remains unclear. We found that the type I TARP Îł-2 (stargazin) is present in lamina II of the superficial dorsal horn (SDH), an area involved in nociception. Consistent with the notion that Îł-2 is associated with surface AMPARs, CNQX, a partial agonist at AMPARs associated with type I TARPs, evoked whole-cell currents in lamina II neurons, but such currents were severely attenuated in Îł-2-lacking stargazer (stg/stg) mice. Examination of EPSCs revealed the targeting of Îł-2 to be synapse specific; the amplitude of spontaneously occurring mEPSCs was reduced in neurons from stg/stg mice, but the amplitude of capsaicin-induced mEPSCs from C-fiber synapses was unaltered. This suggests that Îł-2 is associated with AMPARs at synapses in lamina ll but excluded from those at C-fiber inputs, a view supported by our immunohistochemical co-labeling data. Following induction of peripheral inflammation, a model of hyperalgesia, there was a switch in the current-voltage relationships of capsaicin-induced mEPSCs, from linear to inwardly rectifying, indicating an increased prevalence of calcium permeable (CP-) AMPARs. This effect was abolished in stg/stg mice. Our results establish that while Îł-2 is not typically associated with calcium-impermeable (CI-) AMPARs at C-fiber synapses, it is required for the translocation of CP-AMPARs to these synapses following peripheral inflammation.SIGNIFICANCE STATEMENTIn the brain, transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) critically determine the functional properties of AMPARs, but the contribution of these auxiliary subunits to AMPAR-mediated signaling in the spinal cord remains unclear. An increase in the excitability of neurons within the superficial dorsal horn (SDH) of the spinal cord is thought to underlie heighted pain sensitivity. One mechanism considered to contribute to such long-lived changes is the remodeling of the ionotropic AMPA-type glutamate receptors that underlie fast excitatory synaptic transmission in the SDH. Here we show that the TARP Îł-2 (stargazin) is present in SDH neurons and is necessary in a form of inflammatory pain-induced plasticity, which involves an increase in the prevalence of synaptic calcium-permeable AMPARs
Application of Common Sense Computing for the Development of a Novel Knowledge-Based Opinion Mining Engine
The ways people express their opinions and sentiments have radically changed in the past few years thanks to the advent of social networks, web communities, blogs, wikis and other online collaborative media. The distillation of knowledge from this huge amount of unstructured information can be a key factor for marketers who want to create an image or identity in the minds of their customers for their product, brand, or organisation. These online social data, however, remain hardly accessible to computers, as they are specifically meant for human consumption. The automatic analysis of online opinions, in fact, involves a deep understanding of natural language text by machines, from which we are still very far.
Hitherto, online information retrieval has been mainly based on algorithms relying on the textual representation of web-pages. Such algorithms are very good at retrieving texts, splitting them into parts, checking the spelling and counting their words. But when it comes to interpreting sentences and extracting meaningful information, their capabilities are known to be very limited. Existing approaches to opinion mining and sentiment analysis, in particular, can be grouped into three main categories: keyword spotting, in which text is classified into categories based on the presence of fairly unambiguous affect words; lexical affinity, which assigns arbitrary words a probabilistic affinity for a particular emotion; statistical methods, which calculate the valence of affective keywords and word co-occurrence frequencies on the base of a large training corpus. Early works aimed to classify entire documents as containing overall positive or negative polarity, or rating scores of reviews.
Such systems were mainly based on supervised approaches relying on manually labelled samples, such as movie or product reviews where the opinionistâs overall positive or negative attitude was explicitly indicated. However, opinions and sentiments do not occur only at document level, nor they are limited to a single valence or target. Contrary or complementary attitudes toward the same topic or multiple topics can be present across the span of a document. In more recent works, text analysis granularity has been taken down to segment and sentence level, e.g., by using presence of opinion-bearing lexical items (single words or n-grams) to detect subjective sentences, or by exploiting association rule mining for a feature-based analysis of product reviews. These approaches, however, are still far from being able to infer the cognitive and affective information associated with natural language as they mainly rely on knowledge bases that are still too limited to efficiently process text at sentence level.
In this thesis, common sense computing techniques are further developed and applied to bridge the semantic gap between word-level natural language data and the concept-level opinions conveyed by these. In particular, the ensemble application of graph mining and multi-dimensionality reduction techniques on two common sense knowledge bases was exploited to develop a novel intelligent engine for open-domain opinion mining and sentiment analysis. The proposed approach, termed sentic computing, performs a clause-level semantic analysis of text, which allows the inference of both the conceptual and emotional information associated with natural language opinions and, hence, a more efficient passage from (unstructured) textual information to (structured) machine-processable data.
The engine was tested on three different resources, namely a Twitter hashtag repository, a LiveJournal database and a PatientOpinion dataset, and its performance compared both with results obtained using standard sentiment analysis techniques and using different state-of-the-art knowledge bases such as Princetonâs WordNet, MITâs ConceptNet and Microsoftâs Probase. Differently from most currently available opinion mining services, the developed engine does not base its analysis on a limited set of affect words and their co-occurrence frequencies, but rather on common sense concepts and the cognitive and affective valence conveyed by these. This allows the engine to be domain-independent and, hence, to be embedded in any opinion mining system for the development of intelligent applications in multiple fields such as Social Web, HCI and e-health. Looking ahead, the combined novel use of different knowledge bases and of common sense reasoning techniques for opinion mining proposed in this work, will, eventually, pave the way for development of more bio-inspired approaches to the design of natural language processing systems capable of handling knowledge, retrieving it when necessary, making analogies and learning from experience
Auxiliary Subunit GSG1L Acts to Suppress Calcium-Permeable AMPA Receptor Function
UNLABELLED: AMPA-type glutamate receptors are ligand-gated cation channels responsible for a majority of the fast excitatory synaptic transmission in the brain. Their behavior and calcium permeability depends critically on their subunit composition and the identity of associated auxiliary proteins. Calcium-permeable AMPA receptors (CP-AMPARs) contribute to various forms of synaptic plasticity, and their dysfunction underlies a number of serious neurological conditions. For CP-AMPARs, the prototypical transmembrane AMPAR regulatory protein stargazin, which acts as an auxiliary subunit, enhances receptor function by increasing single-channel conductance, slowing channel gating, increasing calcium permeability, and relieving the voltage-dependent block by endogenous intracellular polyamines. We find that, in contrast, GSG1L, a transmembrane auxiliary protein identified recently as being part of the AMPAR proteome, acts to reduce the weighted mean single-channel conductance and calcium permeability of recombinant CP-AMPARs, while increasing polyamine-dependent rectification. To examine the effects of GSG1L on native AMPARs, we manipulated its expression in cerebellar and hippocampal neurons. Transfection of GSG1L into mouse cultured cerebellar stellate cells that lack this protein increased the inward rectification of mEPSCs. Conversely, shRNA-mediated knockdown of endogenous GSG1L in rat cultured hippocampal pyramidal neurons led to an increase in mEPSC amplitude and in the underlying weighted mean single-channel conductance, revealing that GSG1L acts to suppress current flow through native CP-AMPARs. Thus, our data suggest that GSG1L extends the functional repertoire of AMPAR auxiliary subunits, which can act not only to enhance but also diminish current flow through their associated AMPARs. SIGNIFICANCE STATEMENT: Calcium-permeable AMPA receptors (CP-AMPARs) are an important group of receptors for the neurotransmitter glutamate. These receptors contribute to various forms of synaptic plasticity, and alterations in their expression or regulation are also seen in a number of serious neurological conditions, including stroke, motor neuron disease, and cocaine addiction. Several groups of auxiliary transmembrane proteins have been described that enhance the function and cell-surface expression of AMPARs. We now report that the recently identified auxiliary protein GSG1L decreases weighted mean channel conductance and calcium permeability of CP-AMPARs while increasing polyamine-dependent rectification by diminishing outward current. Our experiments reveal that GSG1L is an auxiliary subunit that can markedly suppress CP-AMPAR function, in both recombinant systems and central neurons
Mutually Destructive Bidding: The FCC Auction Design Problem
Dissatisfaction with previous assignment mechanisms and the desire to raise revenue induced Congress to grant the FCC authority to auction radio licenses. The debate over an appropriate auction design was wide ranging with many imaginative proposals. Many of the arguments and their scientific support are unfortunately not publicly available. Here, we present our side of this debate for the record.
Synergies across license valuations complicate the auction design process. Theory suggests that a âsimpleâ (i.e., non-combinatorial) auction will have difficulty in assigning licenses efficiently in such an environment. This difficulty increases with increases in âfitting complexity.â In some environments, bidding may become âmutually destructive.â Experiments indicate that a combinatorial auction is superior to a simple auction in terms of economic efficiency and revenue generation in bidding environments with a low amount of fitting complexity. Concerns that a combinatorial auction will cause a âthresholdâ problem are not borne out when bidders for small packages can communicate
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