Bottom production in Photon and Pomeron -- induced interactions at the LHC

In this paper we present a detailed comparison of the bottom production in gluon -- gluon, photon -- gluon, photon -- photon, pomeron -- gluon, pomeron -- pomeron and pomeron -- photon interactions at the LHC. The transverse momentum, pseudo -- rapidity and $\xi$ dependencies of the cross sections are calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which allows to obtain realistic predictions for the bottom production with one or two leading intact protons. Moreover, predictions for the the kinematical range probed by the LHCb Collaboration are also presented. Our results indicate that the analysis of the single diffractive events is feasible using the Run I LHCb data.Comment: 8 pages, 3 figures, 1 table. Version published in Physical Review

A system of mobile agents to model social networks

We propose a model of mobile agents to construct social networks, based on a system of moving particles by keeping track of the collisions during their permanence in the system. We reproduce not only the degree distribution, clustering coefficient and shortest path length of a large data base of empirical friendship networks recently collected, but also some features related with their community structure. The model is completely characterized by the collision rate and above a critical collision rate we find the emergence of a giant cluster in the universality class of two-dimensional percolation. Moreover, we propose possible schemes to reproduce other networks of particular social contacts, namely sexual contacts.Comment: Phys. Rev. Lett. (in press

The Potential of Higher Plants as a Source of New Drugs

The plant kingdom is still an untapped reservoir of new molecules with therapeutic potential. A selection of bioactive plant constituents recently discovered are presented with focus on new drugs or lead compounds in an advanced state of development. Obtaining pure new biologically active substances from plants remains a complex task. Biological and chemical screenings are complementary approaches for the rapid detection and isolation of new interesting plant constituents. Biological screening followed by activity-guided fractionation has been successfully used in our laboratories for the discovery of new antifungal metabolites and inhibitors of enzymes involved in the aetiology of prostate hyperplasia. High-performance liquid chromatography (HPLC) coupled to UV spectroscopy (LC/UV), mass spectrometry (LC/MS), and magnetic resonance (LC/NMR) proved to be highly efficient for the chemical screening of crude plant extracts. These hyphenated techniques were extensively used for the investigation of polyphenols with monoamine-oxidase inhibitory (IMAO) properties in Gentianaceae species

HIV transmission during paediatric health care in sub- Saharan Africa – risks and evidence

Health care systems in sub-Saharan Africa are challenged not only to improve care for the increasing number of HIV-infected children, but also to prevent transmission of HIV to other children and health care workers through contaminated medical procedures and needlestick accidents. HIV-infected children aged to 1 year typically have high viral loads, making them dangerous reservoirs for iatrogenic transmission. Most vertically infected children experience HIV-related symptoms early, though many survive beyond 5 years. This leads to high HIV prevalence among inpatient and outpatient children. In nine African studies, HIV prevalence in inpatient children ranged from 8.2% to 63%, roughly 1 - 3 times the prevalence in antenatal women. Investigations of large iatrogenic outbreaks in Russia, Romania, and Libya demonstrate efficient HIV transmission through paediatric health care. Unexplained HIV infections in African children are not rare – studies published through 2003 have recorded more than 300 HIV-infected children with HIV-negative mothers. In addition, several studies have reported much higher HIV prevalence in children 5 - 14 years old than could be expected from mother-to-child transmission alone. Research is required to determine the extent of iatrogenic HIV infection among African children as well as to identify high-risk procedures and settings. Such research can motivate and direct prevention efforts. S Afr Med J 2004; 94: 109-116

Pheophorbide a identified in an Eupatorium perfoliatum extract is a novel lymphatic vascular activator

The lymphatic vascular system is crucial for maintaining tissue fluid homeostasis and immune surveillance. Promoting lymphatic function represents a new strategy to treat several diseases including lymphedema, chronic inflammation and impaired wound healing. By screening a plant extract library, a petroleum ether extract from the aerial parts of Eupatorium perfoliatum (E. perfoliatum) was found to possess lymphangiogenic properties. With the aid of HPLC activity profiling the active compound was identified as pheophorbide a. Both plant extract and pheophorbide a induced the sprouting and tube formation of human primary lymphatic endothelial cells (LECs). The proliferation of the LECs was increased upon treatment with pheophorbide a but not the E. perfoliatum extract. Treatment with the MEK1/2 inhibitor U0126 reduced the LEC sprouting activity, indicating a potential mechanism of action. These studies suggest that pheophorbide a could represent novel natural therapeutic agent to treat human lymphatic vascular insufficiencies

Discovery of a missing disease spreader

This study presents a method to discover an outbreak of an infectious disease in a region for which data are missing, but which is at work as a disease spreader. Node discovery for the spread of an infectious disease is defined as discriminating between the nodes which are neighboring to a missing disease spreader node, and the rest, given a dataset on the number of cases. The spread is described by stochastic differential equations. A perturbation theory quantifies the impact of the missing spreader on the moments of the number of cases. Statistical discriminators examine the mid-body or tail-ends of the probability density function, and search for the disturbance from the missing spreader. They are tested with computationally synthesized datasets, and applied to the SARS outbreak and flu pandemic.Comment: in pres