Looking for Light Pseudoscalar Bosons in the Binary Pulsar System J0737-3039

We present numerical calculations of the photon-light-pseudoscalar-boson conversion in the recently discovered binary pulsar system J0737-3039. Light pseudoscalar bosons (LPBs) oscillate into photons in the presence of strong magnetic fields. In the context of this binary pulsar system, this phenomenon attenuates the light beam emitted by one of the pulsars, when the light ray goes through the magnetosphere of the companion pulsar. We show that such an effect is observable in the gamma-ray band since the binary pulsar is seen almost edge-on, depending on the value of the LPB mass and on the strenght of its two-photon coupling. Our results are surprising in that they show a very sharp and significant (up to 50%) transition probability in the gamma-ray ($>$ tens of MeV) domain. The observations can be performed by the upcoming NASA GLAST mission.Comment: to appear in Phys. Rev. Let

Intensity Thresholds and the Statistics of the Temporal Occurrence of Solar Flares

Introducing thresholds to analyze time series of emission from the Sun enables a new and simple definition of solar flare events, and their interoccurrence times. Rescaling time by the rate of events, the waiting and quiet time distributions both conform to scaling functions that are independent of the intensity threshold over a wide range. The scaling functions are well described by a two parameter function, with parameters that depend on the phase of the solar cycle. For flares identified according to the current, standard definition, similar behavior is found.Comment: 5 pages, 4 figures, revtex

Packet Classification via Improved Space Decomposition Techniques

P ack et Classification is a common task in moder n Inter net r outers. The goal is to classify pack ets into "classes" or "flo ws" according to some ruleset that looks at multiple fields of each pack et. Differ entiated actions can then be applied to the traffic depending on the r esult of the classification. Ev en though rulesets can be expr essed in a r elati v ely compact way by using high le v el languages, the r esulting decision tr ees can partition the sear ch space (the set of possible attrib ute v alues) in a potentially v ery lar ge ( and mor e) number of r egions. This calls f or methods that scale to such lar ge pr oblem sizes, though the only scalable pr oposal in the literatur e so far is the one based on a F at In v erted Segment T r ee [1 ]. In this paper we pr opose a new geometric technique called G-filter f or pack et classification on dimensions. G-filter is based on an impr o v ed space decomposition technique. In addition to a theor etical analysis sho wing that classification in G-filter has time complexity and slightly super -linear space in the number of rules, we pr o vide thor ough experiments sho wing that the constants in v olv ed ar e extr emely small on a wide range of pr oblem sizes, and that G-filter impr o v e the best r esults in the literatur e f or lar ge pr oblem sizes, and is competiti v e f or small sizes as well

Packet Classification via Improved Space Decomposition Techniques

Packet Classification is a common task in modern Internet routers. In a nutshell, the goal is to classify packets into ``classes\u27\u27 or ``flows\u27\u27 according to some ruleset that looks at multiple fields of each packet. Differentiated actions can then be applied to the traffic depending on the result of the classification. One way to approach the task is to model it as a point location problem in a multidimensional space, partitioned into a large number of regions, (up to $10^6$ or more, generated by the number of possible paths in the decision tree resulting from the specification of the ruleset). Many solutions proposed in the literature not to scale well with the size of the problem, with the exception of one based on a Fat Inverted Segment Tree. In this paper we propose a new geometric filtering technique, called {em g-filter}, which is competitive with the best result in the literature, and is based on an improved space decomposition technique. A theoretical worst case asymptotic analysis shows that classification in {em g-filter} has $O(1)$ time complexity, and space complexity close to linear in the number of rules. Additionally, thorough experiments show that the constants involved are extremely small on a wide range of problem sizes, and improve the best results in the literature. Finally, the g-filter method is not limited to 2-dimensional rules, but can handle any number of attributes with only a moderate increased overhead per additional dimension

Linked Data approach for selection process automation in Systematic Reviews

Background: a systematic review identifies, evaluates and synthesizes the available literature on a given topic using scientific and repeatable methodologies. The significant workload required and the subjectivity bias could affect results. Aim: semi-automate the selection process to reduce the amount of manual work needed and the consequent subjectivity bias. Method: extend and enrich the selection of primary studies using the existing technologies in the field of Linked Data and text mining. We define formally the selection process and we also develop a prototype that implements it. Finally, we conduct a case study that simulates the selection process of a systematic literature published in literature. Results: the process presented in this paper could reduce the work load of 20% with respect to the work load needed in the fully manually selection, with a recall of 100%. Conclusions: the extraction of knowledge from scientific studies through Linked Data and text mining techniques could be used in the selection phase of the systematic review process to reduce the work load and subjectivity bia

Black hole and brane production in TeV gravity: A review

In models with large extra dimensions particle collisions with center-of-mass energy larger than the fundamental gravitational scale can generate non-perturbative gravitational objects such as black holes and branes. The formation and the subsequent decay of these super-Planckian objects would be detectable in particle colliders and high energy cosmic ray detectors, and have interesting implications in cosmology and astrophysics. In this paper we present a review of black hole and brane production in TeV-scale gravity.Comment: 40 pages, 14 figures, submitted to the Int. Jou. Mod. Phys.

Parkinson's disease: autoimmunity and neuroinflammation

Parkinson's disease is a neurodegenerative disease that causes the death of dopaminergic neurons in the substantia nigra. The resulting dopamine deficiency in the basal ganglia leads to a movement disorder that is characterized by classical parkinsonian motor symptoms. Parkinson's disease is recognized as the most common neurodegenerative disorder after Alzheimer's disease. PD ethiopathogenesis remains to be elucidated and has been connected to genetic, environmental and immunologic conditions. The past decade has provided evidence for a significant role of the immune system in PD pathogenesis, either through inflammation or an autoimmune response. Several autoantibodies directed at antigens associated with PD pathogenesis have been identified in PD patients. This immune activation may be the cause of, rather than a response to, the observed neuronal loss. Parkinsonian motor symptoms include bradykinesia, muscular rigidity and resting tremor. The non-motor features include olfactory dysfunction, cognitive impairment, psychiatric symptoms and autonomic dysfunction. Microscopically, the specific degeneration of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies, which are brain deposits containing a substantial amount of α-synuclein, have been recognized. The progression of Parkinson's disease is characterized by a worsening of motor features; however, as the disease progresses, there is an emergence of complications related to long-term symptomatic treatment. The available therapies for Parkinson's disease only treat the symptoms of the disease. A major goal of Parkinson's disease research is the development of disease-modifying drugs that slow or stop the neurodegenerative process. Drugs that enhance the intracerebral dopamine concentrations or stimulate dopamine receptors remain the mainstay treatment for motor symptoms. Immunomodulatory therapeutic strategies aiming to attenuate PD neurodegeneration have become an attractive option and warrant further investigation

Molecular-Level Switching of Polymer/Nanocrystal Non-Covalent Interactions and Application in Hybrid Solar Cells

Hy brid composites obtained upon blending conjugated polymers and colloidal inorganic semiconductor nanocrystals are regarded as attractive photo-active materials for optoelectronic applications. Here we demonstrate that tailoring nanocrystal surface chemistry permits to exert control on non-covalent bonding and electronic interactions between organic and inorganic components. The pendant moieties of organic ligands at the nanocrystal surface do not merely confer colloidal stability while hindering charge separation and transport, but drastically impact morphology of hybrid composites during formation from blend solutions. The relevance of our approach to photovoltaic applications is demonstrated for composites based on poly(3-hexylthiophene) and Pbs nanocrystals, considered as inadequate before the submission of this manuscript, which enable the fabrication of hybrid solar cells displaying a power conversion efficiency that reaches 3 %. Upon (quasi)steady-state and time-resolved analisys of the photo-induced processes in the nanocomposites and their organic and inorganic components, we ascertained that electron transfer occurs at the hybrid interface yielding long-lived separated charge carriers, whereas interfacial hole transfer appears slow. Here we provide a reliable alternative aiming at gaining control over macroscopic optoelectronic properties of polymer/nanocrystal composites by acting at the molecular-level via ligands' pendant moieties, thus opening new possibilities towards efficient solution-processed hybrid solar cells