Improved Algorithms for Decremental Single-Source Reachability on Directed Graphs

Recently we presented the first algorithm for maintaining the set of nodes reachable from a source node in a directed graph that is modified by edge deletions with $o(mn)$ total update time, where $m$ is the number of edges and $n$ is the number of nodes in the graph [Henzinger et al. STOC 2014]. The algorithm is a combination of several different algorithms, each for a different $m$ vs. $n$ trade-off. For the case of $m = \Theta(n^{1.5})$ the running time is $O(n^{2.47})$, just barely below $mn = \Theta(n^{2.5})$. In this paper we simplify the previous algorithm using new algorithmic ideas and achieve an improved running time of $\tilde O(\min(m^{7/6} n^{2/3}, m^{3/4} n^{5/4 + o(1)}, m^{2/3} n^{4/3+o(1)} + m^{3/7} n^{12/7+o(1)}))$. This gives, e.g., $O(n^{2.36})$ for the notorious case $m = \Theta(n^{1.5})$. We obtain the same upper bounds for the problem of maintaining the strongly connected components of a directed graph undergoing edge deletions. Our algorithms are correct with high probabililty against an oblivious adversary.Comment: This paper was presented at the International Colloquium on Automata, Languages and Programming (ICALP) 2015. A full version combining the findings of this paper and its predecessor [Henzinger et al. STOC 2014] is available at arXiv:1504.0795

Fast Dynamic Graph Algorithms for Parameterized Problems

Fully dynamic graph is a data structure that (1) supports edge insertions and deletions and (2) answers problem specific queries. The time complexity of (1) and (2) are referred to as the update time and the query time respectively. There are many researches on dynamic graphs whose update time and query time are $o(|G|)$, that is, sublinear in the graph size. However, almost all such researches are for problems in P. In this paper, we investigate dynamic graphs for NP-hard problems exploiting the notion of fixed parameter tractability (FPT). We give dynamic graphs for Vertex Cover and Cluster Vertex Deletion parameterized by the solution size $k$. These dynamic graphs achieve almost the best possible update time $O(\mathrm{poly}(k)\log n)$ and the query time $O(f(\mathrm{poly}(k),k))$, where $f(n,k)$ is the time complexity of any static graph algorithm for the problems. We obtain these results by dynamically maintaining an approximate solution which can be used to construct a small problem kernel. Exploiting the dynamic graph for Cluster Vertex Deletion, as a corollary, we obtain a quasilinear-time (polynomial) kernelization algorithm for Cluster Vertex Deletion. Until now, only quadratic time kernelization algorithms are known for this problem. We also give a dynamic graph for Chromatic Number parameterized by the solution size of Cluster Vertex Deletion, and a dynamic graph for bounded-degree Feedback Vertex Set parameterized by the solution size. Assuming the parameter is a constant, each dynamic graph can be updated in $O(\log n)$ time and can compute a solution in $O(1)$ time. These results are obtained by another approach.Comment: SWAT 2014 to appea

Geochemistry of fluids discharged over the seismic area of the Southern Apennines (Calabria region, Southern Italy): Implications for Fluid-Fault relationships

The first comprehensive geochemical data-set of the fluids circulating over a 14,000 km2-wide seismicprone area of the Southern Apennines, Calabria Region (Italy), is presented here. The geochemical investigations were carried out with the twofold aim of constraining the origin and interactions of the circulating fluids and to investigate possible relationships with local faults. Sixty samples of both thermal and cold waters were collected, from which the dissolved gases were extracted. The geochemical features of the water samples display different types and degrees of water–rock interactions, irrespective of the outlet temperature. The calculated equilibrium temperatures of the thermal waters (60–160 C) and the low heat flow of thewhole study area, are consistent with a heating process due to deep water circulation and rapid upflow through lithospheric structures. The composition of the dissolved gases reveals that crustal-originating gases (N2 and CO2-dominated) feed all the groundwaters. The 3He/4He ratios of the dissolved He, in the range of 0.03–0.22Rac for the thermal waters and 0.05–0.63Rac for the cold waters (Rac = He isotope ratio corrected for atmospheric contamination), are mainly the result of a two-component (radiogenic and atmospheric) mixing, although indications of mantle-derived He are found in some cold waters. As the study area had been hit by 18 of the most destructive earthquakes (magnitude ranging from 5.9 to 7.2) occurring over a 280-a time span (1626–1908) in the Southern Apennines, the reported results on the circulating fluids may represent the reference for a better inside knowledge of the fault-fluid relationships and for the development of long-term geochemical monitoring strategies for the area

Anomalous fluid emission of a deep borehole in a seismically active area of Northern Apennines (Italy)

The Miano borehole, 1047 m deep, is located close to the river Parma in the Northern Apennines, Italy. A measuring station has been installed to observe the discharge of fluids continuously since November 2004. The upwelling fluid of this artesian well is a mixture of thermal water and CH4 as main components. In non-seismogenic areas, a relatively constant fluid emission would be expected, perhaps overlaid with long term variations from that kind of deep reservoir over time. However, the continuous record of the fluid emission, in particular the water discharge, the gas flow rate and the water temperature, show periods of stable values interrupted by anomalous periods of fluctuations in the recorded parameters. The anomalous variations of these parameters are of low amplitude in comparison to the total values but significant in their long-term trend. Meteorological effects due to rain and barometric pressure were not detected in recorded data probably due to reservoir depth and relatively high reservoir overpressure. Influences due to the ambient temperature after the discharge were evaluated by statistical analysis. Our results suggest that recorded changes in fluid emission parameters can be interpreted as a mixing process of different fluid components at depth by variations in pore pressure as a result of seismogenic stress variation. Local seismicity was analyzed in comparison to the fluid physico-chemical data. The analysis supports the idea that an influence on fluid transport conditions due to geodynamic processes exists. Water temperature data show frequent anomalies probably connected with possible precursory phenomena of local seismic events

A comparative analysis of old and recent Ag coins by XRF methodology

The investigation of silver coins dated since the first century B.C. up to recent times, coming from different countries in the world, has successfully generated a growing interest among numismatic researchers. The classification of these coins into originals, copies and imitations - according to their provenance and to their Ag content - has been performed by using the X-ray fluorescence (XRF) analysis. The archaeological challenge is to explain the large diversification of these coins, to determine the differences in composition, weight and physical aspects. A non-destructive physical method was employed to study the properties of silver coins (as in this case) allowing a detailed characterization of the analyzed samples. The XRF analysis was applied to the bulk, through an X-ray tube, and to the surface patina, through an electron beam

An overview of the geochemical characteristics of oceanic carbonatites: New insights from Fuerteventura carbonatites (Canary islands)

The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This paper provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis. We present new data on trace elements in minerals and whole-rock, together with the first noble gases isotopic study (He, Ne, Ar) in apatite, calcite, and clinopyroxene from Fuerteventura carbonatites (Canary Islands). Trace elements show a similar trend as Cape Verde carbonatites, almost tracing the same patterns on multi-element and REE abundance diagrams.3He/4He isotopic ratios of Fuerteventura carbonatites reflect a shallow (sub-continental lithospheric mantle, SCLM) He signature in their petrogenesis, and they clearly differ from Cape Verde carbonatites, i.e., fluids from a deep and low degassed mantle with a primitive plume-derived He signature are involved in their petrogenesis

Anomalous fluid emission of a deep borehole in a seismically active area of Northern Apennines (Italy)

The Miano borehole of 1047 m depth is located close to the river Parma in the Northern Apennines, Italy. A measuring station is installed to observe the discharge of fluids continuously since November 2004. The upwelling fluid of this artesian well is a mixture of thermal water and methane as main components. In non-seismogenic areas, we would expect a relative constant fluid emission perhaps overlaid with long term variations from that kind of deep reservoirs during the time. However, the continuously record of the fluid emission, in particular the water discharge, the gas flow rate and the water temperature, show periods of stable values interrupted by anomalous periods of fluctuations in the recorded parameters. The anomalous variations of these parameters are of low amplitude in comparison to the total values but significant in their long-term trend. Meteorological influences of rain and barometric pressure were not detected in recorded data probably due to reservoir depth and relatively high reservoir overpressure. Influences due to the ambient temperature after the discharge were evaluated by statistical analysis. We consider that recorded changes in fluid emission parameters can be interpreted as a mixing process of different fluid components in depth by variations in pore pressure as result of seismogenic stress variation. Local seismicity was analyzed in comparison to fluid’s physico-chemical data. The analysis supports the idea of an influence to fluid transport conditions due to geodynamic processes exist. Water temperature data show frequent anomalies probably connected with possible precursory phenomena of local seismic events

Desempenho produtivo de ovinos deslanados da raça Santa Inês no Estado do Piauí.

Desempenho reprodutivo; Peso das matrizes; Peso das crias.bitstream/item/35788/1/Bol19.pd

Misincorporation Proteomics Technologies: A Review.

Proteinopathies are diseases caused by factors that affect proteoform conformation. As such, a prevalent hypothesis is that the misincorporation of noncanonical amino acids into a proteoform results in detrimental structures. However, this hypothesis is missing proteomic evidence, specifically the detection of a noncanonical amino acid in a peptide sequence. This review aims to outline the current state of technology that can be used to investigate mistranslations and misincorporations whilst framing the pursuit as Misincorporation Proteomics (MiP). The current availability of technologies explored herein is mass spectrometry, sample enrichment/preparation, data analysis techniques, and the hyphenation of approaches. While many of these technologies show potential, our review reveals a need for further development and refinement of approaches is still required