2,141 research outputs found
Improved shape-signature and matching methods for model-based robotic vision
Researchers describe new techniques for curve matching and model-based object recognition, which are based on the notion of shape-signature. The signature which researchers use is an approximation of pointwise curvature. Described here is curve matching algorithm which generalizes a previous algorithm which was developed using this signature, allowing improvement and generalization of a previous model-based object recognition scheme. The results and the experiments described relate to 2-D images. However, natural extensions to the 3-D case exist and are being developed
The impact of satellite temperature soundings on the forecasts of a small national meteorological service
The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts
Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE
We report an initial study of temperature and emission measure distributions
along four steady loops observed with the Transition Region and Coronal
Explorer (TRACE) at the limb of the Sun. The temperature diagnostic is the
filter ratio of the extreme-ultraviolet 171-angstrom and 195-angstrom
passbands. The emission measure diagnostic is the count rate in the
171-angstrom passband. We find essentially no temperature variation along the
loops. We compare the observed loop structure with theoretical isothermal and
nonisothermal static loop structure.Comment: 10 pages, 3 postscript figures (LaTeX, uses aaspp4.sty). Accepted by
ApJ Letter
Student conceptions about energy transformations: progression from general chemistry to biochemistry
Students commencing studies in biochemistry must transfer and build on concepts they learned in chemistry and biology classes. It is well established, however, that students have difficulties in transferring critical concepts from general chemistry courses; one key concept is âenergy.â Most previous work on studentsâ conception of energy has focused on their understanding of energy in the context of physics (including the idea of âworkâ) and/or their understanding of energy in classical physical and inorganic chemistry contexts (particularly Gibbs Free Energy changes, the second law of thermodynamics, and equilibrium under standard conditions within a closed system). For biochemistry, students must go beyond those basic thermodynamics concepts of work, standard energy changes, and closed systems, and instead they must consider what energy flow, use, and transformation mean in living, open, and dynamic systems. In this study we explored studentsâ concepts about free energy and flow in biological chemical reactions and metabolic pathways by surveys and in-depth interviews. We worked with students in general chemistry classes and biochemistry courses in both an Australian and a US tertiary institution. We address three primary questions (i) What are the most common alternative conceptions held by students when they explain energy-related phenomena in biochemistry?, (ii) What information do students transfer from introductory chemistry and biology when they are asked to consider energy in a biological reaction or reaction pathway?, and (iii) How do students at varying levels of competence articulate their understandings of energy in pathways and biological reactions? The answers to these questions are used to build a preliminary learning progression for understanding âenergyâ in biochemistry. We also propose crucial elements of content knowledge that instructors could apply to help students better grasp this threshold concept in biochemistry
Corporate Restructuring and the Budget Deficit Debate
This paper examines the assumptions underlying the view that large federal budget deficits crowd out private investment and create a twin trade deficit. These assumptions are contrasted with those of an alternative theory which emphasizes the importance of the institutional structures of the financial system in the context of the credit market. In particular, the paper argues that corporations were not crowded out of credit markets; indeed, they borrowed heavily to finance corporate restructuring (mergers, takeovers, leveraged buyouts, equity repurchases, etc.). This restructuring was encouraged by tax considerations, and the resulting loss of revenue contributed to the budget deficit.Deficit
A RECONCEPTUALIZATION OF SOCIAL STRUCTURE OF ACCUMULATION THEORY
This article puts forward a reconceptualization of the theory of a social structure
of accumulation (SSA). The thirty years of neoliberalism presenta problem for SSA
theory. According to current SSA theory, an SSA is an institutional configuration
that for a long period of time promotes rapid capital accumulation and economic growth.
Although neoliberalism is clearly a new and long-lasting institutional structure that
replaced the postwar SSA, growth in the neoliberal economy has been relatively sluggish.
This article offers a revised concept of an SSA, which makes it possible to explain
neoliberalism as an SSA. It argues that every SSA promotes profit-making but does
not necessarily bring accumulation that is rapid by some historical standard. It introduces
the concept of liberal and regulated SSAs and examines the features of both types
of SSA. It considers the implications of this revised SSA theory for understanding
the current capitalist economic crisis.
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Romidepsin for the treatment of relapsed/refractory peripheral T cell lymphoma: prolonged stable disease provides clinical benefits for patients in the pivotal trial.
BACKGROUND: Achievement of durable responses in patients with relapsed/refractory peripheral T cell lymphoma (PTCL) is challenging with current therapies, and there are few data regarding the potential benefits of continuing treatment in patients with the best response of stable disease (SD). Histone deacetylase inhibitors are a novel class of drugs with activity in T cell malignancies. Romidepsin was approved by the US Food and Drug Administration for the treatment of relapsed/refractory PTCL based on a pivotal trial demonstrating an objective response rate of 25 % (33/130), including 15 % with confirmed/unconfirmed complete response and a median duration of response of 28 months. Our objective was to further study the clinical benefits of romidepsin in patients that had the best response of SD.
METHODS: Patients with PTCL relapsed/refractory to â„1 prior therapy were treated with the approved dose of 14 mg/m(2) romidepsin on days 1, 8, and 15 of six 28-day cycles; patients with SD or response after cycle 6 were allowed to continue on study until progression. By protocol amendment, patients treated for â„12 cycles could receive maintenance dosing twice per cycle; after cycle 24, dosing could be further reduced to once per cycle in those who had received maintenance dosing for â„6 months.
RESULTS: Of the 32 patients (25 %) with the best response of SD, 22 had SD for â„90 days (SD90; cycle 4 response assessment). The longest SD was \u3e3 years in a patient who received maintenance dosing of 14 mg/m(2) on days 1 and 15 beginning in cycle 13. Patients with the best response of SD90 or partial response achieved similar overall and progression-free survival. Prolonged dosing of romidepsin was well tolerated.
CONCLUSIONS: We concluded that patients who achieve SD may consider continuing treatment because the clinical benefits of romidepsin may extend beyond objective responses.
TRIAL REGISTRATION: NCT00426764
Mucosal Melanomas of the Head and Neck: The Role of Postoperative Radiation Therapy
Objectives. Mucosal melanomas are rarer than their cutaneous counterparts and are associated with a poorer prognosis. We report the clinical outcomes of patients with mucosal melanomas of the head and neck region generally treated with definitive surgery followed by postoperative radiation therapy (RT). Methods. We reviewed the records of 17 patients treated at the University of Miami in 1990â2007. Patients generally received conventionally fractionated RT regimens to the postoperative bed. Elective nodal RT was not routinely delivered. Eight patients received adjuvant chemotherapy or immunotherapy. Results. Median followup was 35.2 months (range 5â225). As the first site of failure: 3 patients recurred locally, 2 regionally and 2 distantly. All 3 patients who recurred locally had not received RT. Of the 5 locoregional recurrences, 4 were salvaged successfully with multimodality therapy with no evidence of disease at last followup. Overall survival was 64.7% at 2 years and 51.5% at 5 years. Conclusions. Patients with mucosal melanoma of the head and neck are best treated with surgery to achieve negative margins, followed by postoperative RT to optimize local control. Elective nodal irradiation may not be indicated in all cases, as regional failures were not predominant. Distant metastases were fewer when compared to historical data, potentially due to advancements in adjuvant therapies as well as aggressive multi-modality salvage at time of failure
Holomorphic Anomalies in Topological Field Theories
We study the stringy genus one partition function of SCFT's. It is
shown how to compute this using an anomaly in decoupling of BRST trivial states
from the partition function. A particular limit of this partition function
yields the partition function of topological theory coupled to topological
gravity. As an application we compute the number of holomorphic elliptic curves
over certain Calabi-Yau manifolds including the quintic threefold. This may be
viewed as the first application of mirror symmetry at the string quantum level.Comment: 32 pages. Appendix by S.Kat
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