Searching for the scale of homogeneity

We introduce a statistical quantity, known as the $K$ function, related to the integral of the two--point correlation function. It gives us straightforward information about the scale where clustering dominates and the scale at which homogeneity is reached. We evaluate the correlation dimension, $D_2$, as the local slope of the log--log plot of the $K$ function. We apply this statistic to several stochastic point fields, to three numerical simulations describing the distribution of clusters and finally to real galaxy redshift surveys. Four different galaxy catalogues have been analysed using this technique: the Center for Astrophysics I, the Perseus--Pisces redshift surveys (these two lying in our local neighbourhood), the Stromlo--APM and the 1.2 Jy {\it IRAS} redshift surveys (these two encompassing a larger volume). In all cases, this cumulant quantity shows the fingerprint of the transition to homogeneity. The reliability of the estimates is clearly demonstrated by the results from controllable point sets, such as the segment Cox processes. In the cluster distribution models, as well as in the real galaxy catalogues, we never see long plateaus when plotting $D_2$ as a function of the scale, leaving no hope for unbounded fractal distributions.Comment: 9 pages, 11 figures, MNRAS, in press; minor revision and added reference

Etiological and molecular diagnostic of Carrion’s disease in patients from Cajamarca - Perú

[EN] Poster presented in the poster session in the 15th ICID Abstracts. June 13th-16th 2012, Bangkok, Thailand. Session: Emerging Infectious Diseases. Date: Friday, June 15, 2012. Room: Poster & Exhibition Area.Background: Bartonellagenus is a group of facultative intracellular pathogens that posses able to survive and proliferate inside of erythrocytes. Classified within this genus,Bartonella bacilliformisis of special relevance. This microorganism is the etiological agent of the so called Carrion’s Disease (Human bartonellosis). Additionally the presence of sub-clinical cases (asymptomatyc carriers) is of special interest, because acts as a reservoir of this illness. Carrión’s Disease is an endemic illnes in Perú, affecting in a special manner the north interandean valleys. However, the current in use diagnostic techniques (Giemsa Stain) possess low sensitivity and specificity, and due to the fact thatB. bacilliformispossess a low growth (weeks), bacterial cultures lacks of clinical utility. Thus suspictious cases frequently are not confirmed, and the real relevance of this illness remains underestimated. This work is addressed to the direct identification from blood samples ofBartonella baciliformisusing a conventional PCR. All patients were from the Cajamarca area being enrolled by the Epidemiological Surveillance program of DIRESA. Methods: The samples were processed at arriving to the laboratory, by molecular and microbiological techniques. Thus samples were cultured in Blood Columbia Agar (10%), in anaerobic conditions at 28 ◦C for a period of 2 months. Positive cultures were both Giemsa stained and identified by the amplification of a fragment the 16S rRNA gene. Genetic material was directly extracted from blood samples using the Kit High Pure (Roche diagnostic), and a fragment of 438 bp of the 16S rRNA gene was amplified withBartonellagenus specific primers. All positive PCR were sequenced (Macrogen-Korea). Results: A total of 134 blood samples were processed, from this 12 (8.9%) grown in blood agar, while in 18 (13.4%), including the aforementioned 12, the 16 s rRNA gene was amplified. In all cases the sequence analysis showed the presence ofB. bacilliformis Conclusion: Although microbiological culture is the gold standard in the identification ofBartonellaspp., this technique possess strong limitations due to the low growth of these microorganisms. However, the PCR is a rapid technique, possessing a high sensibility and specificity that may be used as routine diagnostic tool for the identification of Carrion’s Disease.Revisión por pare

Carrion's Disease: More Than a Sand Fly-Vectored Illness

Carrion’s disease is a biphasic illness (S1 Fig) caused by an infection of Bartonella bacilliformis, a bacterium that is transmitted through bites of certain phlebotomine sand flies in the Andean valleys of Peru and in some areas of Ecuador and southern Colombia [1,2]. The acute phase, called Oroya fever, is a serious, life-threating illness that mainly affects immunologically naïve populations, such as children. It is also of special concern in pregnant women, because high mortality rates have been described as well as miscarriages, preterm births, and fetal deaths [3]. In this acute phase, the absence or delay of antibiotic treatment may lead to fatal outcomes. In fact, it is considered that, in the pre-antibiotic era, the lethality of this illness ranked between 40% and 88% [1,2]. In the chronic phase, classically considered to occur in previously exposed inhabitants, B. bacilliformis induce endothelial cell proliferation, producing skin lesions called Peruvian warts. In this phase, the lethality is very low [1]. Additionally, the presence of asymptomatic carriers is frequent, although the real numbers remain uncertain because of the difficulty in detecting these subjects

Carrion's disease: an eradicable illness?

Carrion's disease is a neglected tropical disease caused by Bartonella bacilliformis, a vector-borne pathogen restricted to the Andean valleys of Peru, Ecuador and Colombia. Carrion's disease is a biphasic illness; in the acute phase the case-fatality rate can be as high as 88 %, related to high parasitemia, arriving to almost all erythrocytes, and secondary bacterial infections close related with the development of transient immunosuppression in the earlier illness phases. In addition, there are an undefined number of asymptomatic carriers that are reservoirs of the etiological agent of Carrion's disease in endemic areas, they make take into account due to they are the perpetuators of this disease. The actual scenario of Carrion's disease, in which the illness is arriving to new areas, due to the expansion of the vector's distribution, suggests that now may be a crucial time to design a strategy focusing on its elimination

Diarrheagenic Escherichia coli

Conventionally, in Escherichia coli, phylogenetic groups A and B1 are associated with commensal strains while B2 and D are associated with extraintestinal strains. The aim of this study was to evaluate diarrheagenic (DEC) and commensal E. coli phylogeny and its association with antibiotic resistance and clinical characteristics of the diarrheal episode. Phylogenetic groups and antibiotic resistance of 369 E. coli strains (commensal strains and DEC from children with or without diarrhea) isolated from Peruvian children <1 year of age were determined by a Clermont triplex PCR and Kirby-Bauer method, respectively. The distribution of the 369 E. coli strains among the 4 phylogenetic groups was A (40%), D (31%), B1 (21%), and B2 (8%). DEC-control strains were more associated with group A while DEC-diarrhea strains were more associated with group D (P<0.05). There was a tendency (P=0.06) for higher proportion of persistent diarrhea (≥14 days) among severe groups (B2 and D) in comparison with nonsevere groups (A and B1). Strains belonging to group D presented significantly higher percentages of multidrug resistance than the rest of the groups (P>0.01). In summary, DEC-diarrhea strains were more associated with group D than strains from healthy controls

Synthesis and characterization of Pd(II), Pt(II), Cu(I), Ag(I) and Cu(II) complexes with N,O-hybrid pyrazole ligand

The coordination behavior of N,O-hybrid pyrazole-based metal-organic frameworks are described. 2- (3,5-Pyridyl-1H-pyrazol-1-yl)ethanol (L) and its Pd(II), Pt(II), Cu(I), Ag(I) and Cu(II) complexes with different anions have been synthesized and characterized by elemental analysis, conductivity, mass spectrometry, IR, 1H, 13C{1H} and 195Pt{1H} NMR spectroscopies. Complex 1 was also characterized by single crystal X-ray diffraction. For complex 7 has also been possible to perform the UV-Vis and magnetic susceptibility measurements. All complexes are monomers, except the complexes obtained by reaction of the ligand (L) with M(MeCO2)2 (M = Pd(II), Pt(II)) or CuBr2, which are dimers

Preparation, spectroscopic and structural study of copper(II) complexes derived from bulky pyridine ligands

Three different binuclear tetracarboxylato-bridged copper(II) complexes supported by bulky pyridines ligands [Cu(m-MeCO2)2(dPy)]2 (dPy = 3-phenylpyridine (1), 2-benzylpyridine (2) and 4-acetylpyridine (3)) have been synthesised. These compounds were obtained from reaction of [Cu(MeCO2)2(H2O)]2 with pyridine-derived ligands in methanol at room temperature. All compounds were fully characterized by analytical and spectroscopic methods. The molecular structures were determined by X-ray diffraction analysis. All compounds consist of binuclear units where both Cu(II) atoms are linked by four syn-syn carboxylates bridges, showing a paddle-wheel unit, and exhibit interesting intermolecular interactions in the outer coordination sphere

Cocrystals Based on 4,4'-bipyridine: Influence of Crystal Packing on Melting Point

The reactions of piperonylic acid (HPip) and cinnamic acid (HCinn) with 4,4'-bipyridine (4,4'-bipy) have been assayed using the same synthetic methodology, yielding two binary cocrystals with different acid:4,4'-bipy molar ratios, (HPip)(4,4'-bipy) (1) and (HCinn)2(4,4'-bipy) (2). The melting point (m.p.) of these cocrystals have been measured and a remarkable difference (DT 78 C) between them was observed. Moreover, the two cocrystals have been characterized by powder X-ray diffraction (PXRD), elemental analysis (EA), FTIR-ATR, 1H NMR spectroscopies, and single-crystal X-ray diffraction. The study of their structural packings via Hirshfeld surface analysis and energy frameworks revealed the important contribution of the pi..pi and C-H...pi interactions to the formation of different structural packing motifs, this being the main reason for the difference of m.p. between them. Moreover, it has been observed that 1 and 2 presented the same packing motifs as the crystal structure of their corresponding carboxylic acids, but 1 and 2 showed lower m.p. than those of the carboxylic acids, which could be related to the lower strength of the acid-pyridine heterosynthons respect to the acid-acid homosynthons in the crystal structures

Multi-Locus Sequence Typing of Bartonella bacilliformis DNA Performed Directly from Blood of Patients with Oroya's Fever During a Peruvian Outbreak.

Background Bartonella bacilliformis is the etiological agent of Carrion’s disease, a neglected tropical poverty-linked illness. This infection is endemic of Andean regions and it is estimated that approximately 1.7 million of South Americans are at risk. This bacterium is a fastidious slow growing microorganism, which is difficult and cumbersome to isolate from clinical sources, thereby hindering the availability of phylogenetic relationship of clinical samples. The aim of this study was to perform Multi Locus Sequence Typing of B. bacilliformis directly in blood from patients diagnosed with Oroya fever during an outbreak in Northern Peru. Methodology/Principal Findings DNA extracted among blood samples from patients diagnosed with Oroya’s fever were analyzed with MLST, with the amplification of 7 genetic loci (ftsZ, flaA, ribC, rnpB, rpoB, bvrR and groEL) and a phylogenetic analysis of the different Sequence Types (ST) was performed. A total of 4 different ST were identified. The most frequently found was ST1 present in 66% of samples. Additionally, two samples presented a new allelic profile, belonging to new STs (ST 9 and ST 10), which were closely related to ST1. Conclusions/Significance The present data demonstrate that B. bacilliformis MLST studies may be possible directly from blood samples, being a promising approach for epidemiological studies. During the outbreak the STs of B. bacilliformis were found to be heterogeneous, albeit closely related, probably reflecting the evolution from a common ancestor colonizing the area. Additional studies including new samples and areas are needed, in order to obtain better knowledge of phylogenetic scenario B. bacilliformisThis work has been supported by the Spanish Network for the Research in Infectious Diseases [REIPI RD12/0015],by Generalitat de Catalunya, Departament d’Universitats, Recerca i Societat de la Informació [2014 SGR 26] and by by a grant of the Instituto de Salud Carlos III - Spain (PI11/ 00983) which included FEDER funds (JR). MJP has a postdoctoral fellowship from CONCYTEC/ FONDECYT (grant number: CG05-2013- FONDECYT). JR has a fellowship from the programRevisión por pare