A perturbative approach to non-linearities in the information carried by a two layer neural network

We evaluate the mutual information between the input and the output of a two layer network in the case of a noisy and non-linear analogue channel. In the case where the non-linearity is small with respect to the variability in the noise, we derive an exact expression for the contribution to the mutual information given by the non-linear term in first order of perturbation theory. Finally we show how the calculation can be simplified by means of a diagrammatic expansion. Our results suggest that the use of perturbation theories applied to neural systems might give an insight on the contribution of non-linearities to the information transmission and in general to the neuronal dynamics.Comment: Accepted as a preprint of ICTP, Triest

Evaporation Channel as a Tool to Study Fission Dynamics

The dynamics of the fission process is expected to affect the evaporation residue cross section because of the fission hindrance due to the nuclear viscosity. Systems of intermediate fissility constitute a suitable environment for testing such hypothesis, since they are characterized by evaporation residue cross sections comparable or larger than the fission ones. Observables related to emitted charged particle, due to their relatively high emission probability, can be used to put stringent constraints on models describing the excited nucleus decay and to recognize the effects of fission dynamics. In this work model simulations are compared with the experimental data collected via the ^{32}S + ^{100}Mo reaction at E_{lab}= 200 MeV. By comparing an extended set of evaporation channel observables the limits of the statistical model and the large improvement coming by using a dynamical model are evidenced. The importance of using a large angular covering apparatus to extract the observable is stressed. The opportunity to measure more sensitive observables by a new detection device in operation at LNL are also discussed.Comment: v1: 7 pages, 6 figure

Replica symmetric evaluation of the information transfer in a two-layer network in presence of continuous+discrete stimuli

In a previous report we have evaluated analytically the mutual information between the firing rates of N independent units and a set of multi-dimensional continuous+discrete stimuli, for a finite population size and in the limit of large noise. Here, we extend the analysis to the case of two interconnected populations, where input units activate output ones via gaussian weights and a threshold linear transfer function. We evaluate the information carried by a population of M output units, again about continuous+discrete correlates. The mutual information is evaluated solving saddle point equations under the assumption of replica symmetry, a method which, by taking into account only the term linear in N of the input information, is equivalent to assuming the noise to be large. Within this limitation, we analyze the dependence of the information on the ratio M/N, on the selectivity of the input units and on the level of the output noise. We show analytically, and confirm numerically, that in the limit of a linear transfer function and of a small ratio between output and input noise, the output information approaches asymptotically the information carried in input. Finally, we show that the information loss in output does not depend much on the structure of the stimulus, whether purely continuous, purely discrete or mixed, but only on the position of the threshold nonlinearity, and on the ratio between input and output noise.Comment: 19 pages, 4 figure

Thyroid nodules treated with percutaneous radiofrequency thermal ablation: a comparative study

Percutaneous radiofrequency thermal ablation (RTA) was reported as an effective tool for the management of thyroid nodules (TNs). The aim of this study was to investigate the effects of RTA and to establish whether they were treatment-related by comparison with a matched, untreated control group

Lupus vasculitis: An overview

Lupus vasculitis (LV) is one of the secondary vasculitides occurring in the setting of systemic lupus erythematosus (SLE) in approximately 50% of patients. It is most commonly associated with small vessels, but medium-sized vessels can also be affected, whereas large vessel involvement is very rare. LV may involve different organ systems and present in a wide variety of clinical manifestations according to the size and site of the vessels involved. LV usually portends a poor prognosis, and a prompt diagnosis is fundamental for a good outcome. The spectrum of involvement ranges from a relatively mild disease affecting small vessels or a single organ to a multiorgan system disease with life-threatening manifestations, such as mesenteric vasculitis, pulmonary hemorrhage, or mononeuritis multiplex. Treatment depends upon the organs involved and the severity of the vasculitis process. In this review, we provide an overview of the different forms of LV, describing their clinical impact and focusing on the available treatment strategies

Drug resistance in multiple myeloma: Soldiers and weapons in the bone marrow niche

Multiple myeloma (MM) is still an incurable disease, despite considerable improvements in treatment strategies, as resistance to most currently available agents is not uncommon. In this study, data on drug resistance in MM were analyzed and led to the following conclusions: resistance occurs via intrinsic and extrinsic mechanisms, including intraclonal heterogeneity, drug efflux pumps, alterations of drug targets, the inhibition of apoptosis, increased DNA repair and interactions with the bone marrow (BM) microenvironment, cell adhesion, and the release of soluble factors. Since MM involves the BM, interactions in the MM-BM microenvironment were examined as well, with a focus on the cross-talk between BM stromal cells (BMSCs), adipocytes, osteoclasts, osteoblasts, endothelial cells, and immune cells. Given the complex mechanisms that drive MM, next-generation treatment strategies that avoid drug resistance must target both the neoplastic clone and its non-malignant environment. Possible approaches based on recent evidence include: (i) proteasome and histone deacetylases inhibitors that not only target MM but also act on BMSCs and osteoclasts; (ii) novel peptide drug conjugates that target both the MM malignant clone and angiogenesis to unleash an effective anti-MM immune response. Finally, the role of cancer stem cells in MM is unknown but given their roles in the development of solid and hematological malignancies, cancer relapse, and drug resistance, their identification and description are of paramount importance for MM management

Levantamento fitossociológico de plantas daninhas na cultura do girassol.

O levantamento fitossociológico da comunidade de plantas daninhas na cultura do girassol foi realizado em duas épocas distintas: no desenvolvimento inicial da cultura (entre 20 e 40 dias após a semeadura) e na pré-colheita do girassol. As espécies de plantas daninhas foram identificadas e quantificadas pelo método do quadrado inventário (1,0 x 1,0 m), com amostragem de 12 m2 por área. Os levantamentos foram realizados em 54 propriedades de seis municípios da região do cerrado e em 38 propriedades de oito municípios da região dos pampas, que são as duas principais regiões produtoras brasileiras. Foram registrados a frequência, a frequência relativa, a densidade, a densidade relativa, a abundância, a abundância relativa, o índice de importância relativa e o índice de similaridade. No total, foram identificadas 60 espécies de plantas daninhas, sendo 17 presentes em ambas as regiões. Asteraceae e Poaceae foram as duas principais famílias, entre as 16 encontradas. As principais espécies presentes no cerrado foram Euphorbia heterophylla, Chamaesyce hirta, Ageratum conyzoides, Commelina benghalensis, Zea mays e Bidens sp. As principais espécies presentes no Rio Grande do Sul foram Bidens sp., Raphanus raphanistrum, Lolium multiflorum, Gnaphalium spicatum, Sonchus oleraceus, Euphorbia heterophylla, Sida rhombifolia, Digitaria sp. e Ipomea sp. A densidade das plantas daninhas foi maior na fase de pré-colheita do que no desenvolvimento inicial da cultura, em ambas as regiões, sendo de 30,84 plantas m-2 e 23,58 plantas m-2, respectivamente, para o cerrado, e de 23,19 plantas m-2 e 21,41 plantas m-2, para o Rio Grande do Sul. O índice de similaridade dentro das regiões foi de 0,91 para os levantamentos do cerrado e de 0,79 para os do Rio Grande do Sul. Entretanto, entre as regiões, os índices ficaram abaixo de 0,5, mostrando similaridade mediana entre a flora daninha do cerrado e a do Rio Grande do Sul, na cultura do girassol, nas duas épocas estudadas.Palavras-chave: competição, fitossociologia, Helianthus annuus, infestação. A phytosociological survey of the weed communities present in sunflower crop was carried out during two distinct crop stages: early development and pre-harvest. Weed species were identified and quantified according to the inventory square method (1.0 x 1.0 m), using 12 m2 of sampling per area surveyed. At each stage, the survey was carried out on 54 farms of six counties of the cerrado (savanna region, Central Brazil) and 38 farms of eight counties of the Pampas (region in the State of Rio Grande do Sul, the Southernmost state in Brazil), which are the two main Brazilian sunflower production regions. Frequency, relative frequency, density, relative density, abundance, relative abundance, relative importance index, and similarity index were computed. A total of 60 weed species were identified, 17 of which were present in both regions. Asteraceae and Poaceae were the two main families among the 16 found. The main species present in the cerrado were Euphorbia heterophylla, Chamaesyce hirta, Ageratum conyzoides, Commelina benghalensis, Zea mays and Bidens sp. The most abundant species present in the State of Rio Grande do Sul were Bidens sp., Raphanus raphanistrum, Lolium multiflorum, Gnaphalium spicatum, Sonchus oleraceus, Euphorbia heterophylla, Sida rhombifolia, Digitaria sp. and Ipomea sp. Weed density was higher at pre-harvest than at the early stage of the crop, in both regions: 30.84 plants m-2 and 23.58 plants m-2, respectively, for the cerrado region and 23.19 plants m-2 FORMATAR and 21.41 plants m-2, respectively, for the Pampas region. The similarity index within each region was 0.91 for the cerrado and 0.79 for the Pampas. Nevertheless, the region indices remained below 0.5, showing median similarity between the weed flora affecting sunflower crop at the ?cerrado? and that at the ?Pampas? during the two growth stages studied

As plantas daninhas e a semeadura direta.

Comportamento das plantas daninhas; Métodos de controle; Tecnologia da aplicação; Novas abordagens.bitstream/CNPSO/18514/1/circtec33.pd

Original article: Immuno-chemotherapy of advanced colorectal cancer with alpha-2a interferon and 5-Fluorouracil immunopharmacological studies

Summary: Twelve patients with metastatic colorectal cancer received alternating cycles of low immunomodulat-ing doses of alpha-IFN + 5-Fluorouracil (5-FU) or 5-FU alone. Hematological, biochemical and physical evaluation showed that both treatment cycles were well tolerated. However, transient fever and moderate flu-like symptoms were observed following alpha-IFN administration. Treatment with 5-FU alone produced long-lasting inhibition of CD8+ T lymphocytes, but did not depress NK activity (NKA). Combined treatment with alpha-IFN produced a short-term increase of NKA and antagonized the effect of 5-FU on CD8+ cells on day 5 of the cycle. Parallel studies on in vitro models showed antiproliferative effects of 5-FU on PHA-stimulated MNC and confirmed the preferential inhibition of CD8+ cells. Pretreatment with alpha-IFN did not reverse the effect of 5-FU on CD8+ lymphocytes, but partially protected MNC from the toxic effects of the drug. This was presumably due to the cytostatic effects induced by alpha-IFN on MNC before exposure to the cycle-specific antineoplastic agent. This investigation suggests that alpha-IFN could play a positive role in immuno-chemotherapy of colorectal cancer through multiple mechanisms not entirely related to direct antitumor effects of the agent. © 1991 Kluwer Academic Publishers