1,924 research outputs found
Snowmass 2001: Jet Energy Flow Project
Conventional cone jet algorithms arose from heuristic considerations of LO
hard scattering coupled to independent showering. These algorithms implicitly
assume that the final states of individual events can be mapped onto a unique
set of jets that are in turn associated with a unique set of underlying hard
scattering partons. Thus each final state hadron is assigned to a unique
underlying parton. The Jet Energy Flow (JEF) analysis described here does not
make such assumptions. The final states of individual events are instead
described in terms of flow distributions of hadronic energy. Quantities of
physical interest are constructed from the energy flow distribution summed over
all events. The resulting analysis is less sensitive to higher order
perturbative corrections and the impact of showering and hadronization than the
standard cone algorithms.Comment: REVTeX4, 13 pages, 6 figures; Contribution to the P5 Working Group on
QCD and Strong Interactions at Snowmass 200
Intra- and interspecific polymorphisms ofLeishmania donovani andL. tropica minicircle DNA
A pair of degenerate polymerase chain reaction (PCR) primers (LEI-1, TCG GAT CC[C,T] [G,C]TG GGT AGG GGC GT; LEI-2, ACG GAT CC[G,C] [G,C][A,C]C TAT [A,T]TT ACA CC) defining a 0.15-kb segment ofLeishmania minicircle DNA was constructed. These primers amplified not only inter- but also intraspecifically polymorphic sequences. Individual sequences revealed a higher intraspecific than interspecific divergence. It is concluded that individual sequences are of limited relevance for species determination. In contrast, when a data base of 19 different sequences was analyzed in a dendrographic plot, an accurate species differentiation was feasible
Subthalamic responses to motor cortex stimulation:Selective targeting of the subthalamic motor area
Introduction: Over the last decades, it has been shown consistently that deep brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates motor symptoms in Parkinson (PD) patients. However, in a substantial number of patients the beneficial effects of STN DBS are overshadowed by cognitive and/or limbic alterations. These side effects of STN DBS are thought to be caused by stimulation of the associative and limbic pathways that run through the STN. We hypothesize that an optimal effect of STN DBS on the motor symptoms without inducing cognitive and limbic side effects can be achieved by selective stimulation of the STN motor region by improved targeting. To achieve this goal, we made use of the cortico-subthalamic projection. We hypothesize that in PD patients motor cortex stimulation (MCS) evokes a specific response in the dorsolateral part of the STN, supposedly the STN motor area, that can be seen in both single unit activity and local field potentials (LFP). Material and Methods: Here we describe the results of one PD patient in which we performed MCS during the intra-operative STN microrecordings. In total, we measured single unit activity of eight neurons at various locations in the STN and LFP’s at the same locations. Data were analyzed using Matlab. All recordings were high pass filtered, the stimulus artifact was removed by time shifting, peristimulus time histograms were constructed from which significant excitatory and inhibitory responses were determined using the change point analysis. Results: The STN neurons had an average spontaneous firing rate of 64.6±36.3 Hz. Within the STN responses to MCS were seen, while outside the borders of the STN no responses were found. Responses differed between ventro-dorsal regions in the anterior-posterior and medio-lateral plane. In the anterior and lateral electrode at dorsal levels of the STN a significant early excitation (~10-50ms) and subsequent inhibition (50-110ms) were seen. The lateral electrode also showed a late excitation (~115-170ms). The responses we found were partially similar to reports in animal studies, but we did not observe the typical triphasic response. Conclusion: We found responses in the STN during MCS, which were significantly different in the dorsally recorded neurons in the lateral and anterior trajectory compared to the neurons recorded in other regions of the STN. In the near future MCS could be a novel tool to determine the motor area of the STN to optimize targeting for DBS in PD patients, thereby preventing cognitive and limbic side effect
Predicate Abstraction for Linked Data Structures
We present Alias Refinement Types (ART), a new approach to the verification
of correctness properties of linked data structures. While there are many
techniques for checking that a heap-manipulating program adheres to its
specification, they often require that the programmer annotate the behavior of
each procedure, for example, in the form of loop invariants and pre- and
post-conditions. Predicate abstraction would be an attractive abstract domain
for performing invariant inference, existing techniques are not able to reason
about the heap with enough precision to verify functional properties of data
structure manipulating programs. In this paper, we propose a technique that
lifts predicate abstraction to the heap by factoring the analysis of data
structures into two orthogonal components: (1) Alias Types, which reason about
the physical shape of heap structures, and (2) Refinement Types, which use
simple predicates from an SMT decidable theory to capture the logical or
semantic properties of the structures. We prove ART sound by translating types
into separation logic assertions, thus translating typing derivations in ART
into separation logic proofs. We evaluate ART by implementing a tool that
performs type inference for an imperative language, and empirically show, using
a suite of data-structure benchmarks, that ART requires only 21% of the
annotations needed by other state-of-the-art verification techniques
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