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Search Results: 1 - 10 of 3059 matches for " Piotr Kramarz "
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Antibiotic control of antibiotic resistance in hospitals: a simulation study
Michael Haber, Bruce R Levin, Piotr Kramarz
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-254
Abstract: We developed a simple model that describes the transmission of drug-sensitive and drug-resistant bacteria in a small hospital. Colonized patients may be treated with a standard drug, for which there is some resistance, and with a second-line drug, for which there is no resistance. We then ran deterministic and stochastic simulation programs, based on this model, to predict the effectiveness of various treatment strategies.The results of the analysis using our stochastic model support the predictions of the deterministic models; not only will the implementation of any of the above listed measures substantially reduce the incidences of hospital-acquired infections and the frequency of resistance, the effects of their implementation should be seen in months rather than the years or decades anticipated to control resistance in open communities. How effectively and how rapidly the application of second-line drugs will contribute to the decline in the frequency of resistance to the first-line drugs depends on how these drugs are administered. The earlier the switch to second-line drugs, the more effective this protocol will be. Switching to second-line drugs at random is more effective than switching after a defined period or only after there is direct evidence that the patient is colonized with bacteria resistant to the first antibiotic.The incidence of hospital-acquired bacterial infections and frequencies of antibiotic resistant bacteria can be markedly and rapidly reduced by different readily implemented procedures. The efficacy using second line drugs to achieve these ends depends on the protocol used for their administration.Over the past two decades, antibiotic resistance has become an increasingly grave health problem, serious enough for some to see this not-unanticipated product of evolution as foretelling of the end of the antibiotic era [1]. Because of resistance, bacterial infections that had been readily cleared by antibiotics are lasting longer and are more
Revision of Parastrapotherium (Mammalia, Astrapotheria) and other Deseadan astrapotheres of Patagonia
Kramarz,Alejandro G.; Bond,Mariano;
Ameghiniana , 2008,
Abstract: parastrapotherium ameghino, 1895 is one of the most characteristic faunal elements of the deseadan south american land mammal age (late oligocene) of patagonia, and seven species have been described for that age. the genus was traditionally differentiated from astrapotherium by its giant size and by having a higher number of upper and lower premolars. the revision of the dentition of parastrapotherium revealed that this genus has only one more lower premolar than astrapotherium. other differential features are: lower crowned cheek teeth, cingulum absent at base of labial fold in all upper cheek teeth, upper premolars with labial fold less prominent and with broader base, crown of lower incisors proportionally more robust and buccolingually broader, lower molars with bunoid "pillar", lingual cingulum absent at the base of metaconid, and lower cheek teeth with very superficial labial flexid. of the described deseadan species, p. holmbergi and p. martiale ameghino are herein interpreted as valid. the validity of p. ephebicum ameghino is uncertain. astrapotherium voghti mercerat is valid and herein provisionally transferred to parastrapotherium. liarthrus copei ameghino, previously considered as synonym of p. holmbergi, should be kept in a separate genus. the phylogenetic relationships of parastrapotherium are still uncertain, because it has some features suggesting uruguaytheriine affinities (lower molar cingulum absent at the base of metaconid and very superficial labial flexids), whereas the dental formula and the degree of hypsodonty suggest a very basal position among the oligocene - miocene astrapotheres. cladistic analysis is pending on further additional studies on the still poorly known astraponotus and other astrapotheriids.
Los Litopterna (Mammalia) de la Formación Pinturas, Mioceno Temprano-Medio de Patagonia
Kramarz,Alejandro G.; Bond,Mariano;
Ameghiniana , 2005,
Abstract: the litopterns from the pinturas formation (ameghino′s " astrapothericulan beds") are examined. four species referable to the proterotheriidae are recognized for the lower and middle sequences of this unit: picturotherium migueli gen. et sp. nov, lambdaconus lacerum (ameghino), tetramerorhinus prosistens (ameghino), and t. fleaglei soria. these species retain plesiomorphic dental features, as the labial folds of the paracone and metacone in the upper molars and the little development of the neoparaconid-neoparalophid in lower molars, characteristic of the deseadan and colhuehuapian proterotheriids (soria′s "oligocene group"). proterotheriids with more derived dental morphotypes, tetramerorhinus cingulatum ? (ameghino) and diadiaphorus ? caniadensis sp. nov., are recorded at those localities referred to the upper sequence. this stratigraphic distribution agree with that of the hystricognath rodents and palaeothentid marsupials, and reinforces the hypothesis that the lower and middle sequence of the pinturas formation bear a mammal assemblage different from and older than those derived from the typical santacrucian localities of the santa cruz formation. macraucheniids are only recorded in those levels interpreted as belonging to the upper sequence of the pinturas formation. the absence of macrauqueniids in the lower and middle sequences of the pinturas formation could be the consequence of peculiar and still not well determined palaeoenvironmental conditions during early pinturas times.
New Methodology for Estimating the Burden of Infectious Diseases in Europe
Mirjam Kretzschmar ,Marie-Josée J. Mangen,Paulo Pinheiro,Beate Jahn,Eric M. Fèvre,Silvia Longhi,Taavi Lai,Arie H. Havelaar,Claudia Stein,Alessandro Cassini,Piotr Kramarz,for the BCoDE consortium
PLOS Medicine , 2012, DOI: 10.1371/journal.pmed.1001205
Abstract:
Estimates of Pandemic Influenza Vaccine Effectiveness in Europe, 2009–2010: Results of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) Multicentre Case-Control Study
Marta Valenciano ,Esther Kissling,Jean-Marie Cohen,Beatrix Oroszi,Anne-Sophie Barret,Caterina Rizzo,Baltazar Nunes,Daniela Pitigoi,Amparro Larrauri Cámara,Anne Mosnier,Judith K. Horvath,Joan O'Donnell,Antonino Bella,Raquel Guiomar,Emilia Lupulescu,Camelia Savulescu,Bruno C. Ciancio,Piotr Kramarz,Alain Moren
PLOS Medicine , 2011, DOI: 10.1371/journal.pmed.1000388
Abstract: Background A multicentre case-control study based on sentinel practitioner surveillance networks from seven European countries was undertaken to estimate the effectiveness of 2009–2010 pandemic and seasonal influenza vaccines against medically attended influenza-like illness (ILI) laboratory-confirmed as pandemic influenza A (H1N1) (pH1N1). Methods and Findings Sentinel practitioners swabbed ILI patients using systematic sampling. We included in the study patients meeting the European ILI case definition with onset of symptoms >14 days after the start of national pandemic vaccination campaigns. We compared pH1N1 cases to influenza laboratory-negative controls. A valid vaccination corresponded to >14 days between receiving a dose of vaccine and symptom onset. We estimated pooled vaccine effectiveness (VE) as 1 minus the odds ratio with the study site as a fixed effect. Using logistic regression, we adjusted VE for potential confounding factors (age group, sex, month of onset, chronic diseases and related hospitalizations, smoking history, seasonal influenza vaccinations, practitioner visits in previous year). We conducted a complete case analysis excluding individuals with missing values and a multiple multivariate imputation to estimate missing values. The multivariate imputation (n = 2902) adjusted pandemic VE (PIVE) estimates were 71.9% (95% confidence interval [CI] 45.6–85.5) overall; 78.4% (95% CI 54.4–89.8) in patients <65 years; and 72.9% (95% CI 39.8–87.8) in individuals without chronic disease. The complete case (n = 1,502) adjusted PIVE were 66.0% (95% CI 23.9–84.8), 71.3% (95% CI 29.1–88.4), and 70.2% (95% CI 19.4–89.0), respectively. The adjusted PIVE was 66.0% (95% CI ?69.9 to 93.2) if vaccinated 8–14 days before ILI onset. The adjusted 2009–2010 seasonal influenza VE was 9.9% (95% CI ?65.2 to 50.9). Conclusions Our results suggest good protection of the pandemic monovalent vaccine against medically attended pH1N1 and no effect of the 2009–2010 seasonal influenza vaccine. However, the late availability of the pandemic vaccine and subsequent limited coverage with this vaccine hampered our ability to study vaccine benefits during the outbreak period. Future studies should include estimation of the effectiveness of the new trivalent vaccine in the upcoming 2010–2011 season, when vaccination will occur before the influenza season starts. Please see later in the article for the Editors' Summary
The Pathogen- and Incidence-Based DALY Approach: An Appropriated Methodology for Estimating the Burden of Infectious Diseases
Marie-Josée J. Mangen, Dietrich Plass, Arie H. Havelaar, Cheryl L. Gibbons, Alessandro Cassini, Nikolai Mühlberger, Alies van Lier, Juanita A. Haagsma, R. John Brooke, Taavi Lai, Chiara de Waure, Piotr Kramarz, Mirjam E. E. Kretzschmar, on behalf of the BCoDE consortium
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079740
Abstract: In 2009, the European Centre for Disease Prevention and Control initiated the ‘Burden of Communicable Diseases in Europe (BCoDE)’ project to generate evidence-based and comparable burden-of-disease estimates of infectious diseases in Europe. The burden-of-disease metric used was the Disability-Adjusted Life Year (DALY), composed of years of life lost due to premature death (YLL) and due to disability (YLD). To better represent infectious diseases, a pathogen-based approach was used linking incident cases to sequelae through outcome trees. Health outcomes were included if an evidence-based causal relationship between infection and outcome was established. Life expectancy and disability weights were taken from the Global Burden of Disease Study and alternative studies. Disease progression parameters were based on literature. Country-specific incidence was based on surveillance data corrected for underestimation. Non-typhoidal Salmonella spp. and Campylobacter spp. were used for illustration. Using the incidence- and pathogen-based DALY approach the total burden for Salmonella spp. and Campylobacter spp. was estimated at 730 DALYs and at 1,780 DALYs per year in the Netherlands (average of 2005–2007). Sequelae accounted for 56% and 82% of the total burden of Salmonella spp. and Campylobacter spp., respectively. The incidence- and pathogen-based DALY methodology allows in the case of infectious diseases a more comprehensive calculation of the disease burden as subsequent sequelae are fully taken into account. Not considering subsequent sequelae would strongly underestimate the burden of infectious diseases. Estimates can be used to support prioritisation and comparison of infectious diseases and other health conditions, both within a country and between countries.
Time Dilation as Field  [PDF]
Piotr Ogonowski
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.32027
Abstract: It is proved, there is no aether and time-space is the only medium for electromagnetic wave. However, considering time-space as the medium we may expect, there should exist field equations, describing electromagnetic wave as disturbance in time-space structure propagating in the time-space. I derive such field equations and show that gravitational field as well as electromagnetic field may be considered through one phenomena-time dilation.
Estratigrafía, mamíferos fósiles y edad de las secuencias volcanosedimentarias eoceno-miocenas de la sierra de Huantraico-sierra Negra y cerro Villegas (provincia del Neuquén, Argentina)
Garrido,Alberto; Kramarz,Alejandro; Forasiepi,Analía; Bond,Mariano;
Andean geology , 2012, DOI: 10.5027/andgeoV39n3-a07
Abstract: we present here the recent advances in understanding the stratigraphy and age of the cenozoic volcanic and sedimentary sequences exposed on the area of sierra huantraico-sierra negra and cerro villegas (pehuenches department, neuquén province). stratigraphic analyses and recovered fossil remains allow us to recognize and differentiate six litostratigraphic units: a. the 'rodados lustrosos' (late eocene-early? oligocene), composed of coarse-grained texturally mature conglomerates (up to 18 m thick), deposited on a strong paleorelief of eroded pre-eocene sedimentary rocks (inca diastrophic phase); b. the rincón escondido formation (nom. nov.) (early oligocene-lower late oligocene), composed of sandy fluvial deposits linked to a strong pyroclastic source (31 m), occupies and fills the same paleorelief on which the 'rodados lustrosos' lies; c. the sierra negra formation (nom. nov.) (aquitanian-burdigalian, early miocene) overlies a younger paleorelief that erodes into deposits as old as early cretaceous (pehuenche diastrophic phase); this unit can be subdivided into the filo morado member (up to 250 m of olivine-alkaline basalts, pyroclastic rocks, and volcanogenic deposits) and the puesto tillerías member (nom. nov.) (up to 600 m of basalts and andesitic rocks with interbedded tuffs and tuffites); d. the pichi tril formation (late burdigalian-langhian) is composed of andesitic intrusive bodies linked to deformation that occurred by the end of the early miocene (quechua diastrophic phase); e. the desfiladero negro formation (early tortonian) forms a set of basic dikes that cross the rest of the succession - an intrusion related to earliest late miocene deformation; f. the la tiza formation (late? tortonian-early messinian, late miocene), composed of up to 85 m of coarse-grained oligomictic conglomerates with low textural maturity, originated from the erosion of volcanic bodies and basaltic flows of the sierra negra formation. this entire succession was again deformed at
Estratigrafía y vertebrados (Aves y Mammalia) de la Formación Cerro Bandera, Mioceno Temprano de la Provincia del Neuquén, Argentina Stratigraphy and vertebrates (Aves and Mammalia) from the Cerro Bandera Formation, Early Miocene of Neuquén Province, Argentina
Alejandro Kramarz,Alberto Garrido,Analía Forasiepi,Mariano Bond
Revista geológica de Chile , 2005,
Abstract: La Formación Cerro Bandera comprende una serie de peque os afloramientos aislados, que conforman los relictos de un antiguo relleno aluvial desarrollado sobre peque os valles locales. Se compone de una sucesión de depósitos piroclásticos reelaborados con intercalaciones de piroclastitas primarias y escasos niveles de areniscas. Estos depósitos fueron originalmente reconocidos en el extremo nordeste de la Barda Negra, sur de Cerro Bandera y noroeste de Sierra del Portezuelo; nuevos afloramientos son reconocidos aquí en la vertiente noroeste del cerro Bayo Mesa, Provincia del Neuquén, Argentina. Los restos fósiles exhumados corresponden a aves (Falconidae) y mamíferos (17 familias), entre los que se destacan Cramauchenia normalis Ameghino, Proadinotherium cf. P. muensteri Ameghino, Eosteiromys sp. y Caviocricetus lucasi Vucetich y Verzi, junto con una especie de Protypotherium con dentadura más primitiva que las conocidas para la Edad Santacrucense. Esta asociación confirma una Edad Mamífero Colhuehuapense (Mioceno Temprano) para esta unidad. La fauna exhibe marcadas diferencias con la registrada en la sección inferior de la Formación Chichinales, Provincia de Río Negro. El grado de diferenciación faunística entre estas dos unidades posiblemente sincrónicas podría obedecer a diferencias en los factores paleoambientales locales The Cerro Bandera Formation comprises a series of isolated outcrops that represent the relicts of an old alluvial filling developed on small local valleys. It is composed of a succession of reworked pyroclastic deposits alternating with primary pyroclastic and scant sandstone levels. These deposits were originally recognized at the northeast of Barda Negra, south of Cerro Bandera and northwest of Sierra del Portezuelo; new exposures are herein recognised to the northwestern slope of Cerro Bayo Mesa, Neuquén Province, Argentina. The recovered fossil remains correspond to birds (Falconidae) and 17 families of mammals, among which are remarkable Cramauchenia normalis Ameghino, Proadinotherium cf. P. muensteri Ameghino, Eosteiromys sp. and Caviocricetus lucasi (Vucetich y Verzi), plus a species of Protypotherium with more primitive dentition than those known of the Santacrucian Age. This association confirms a Colhuehuapian SALMA (Early Miocene) for this unit. This fauna is markedly different from that recorded from the lower section of the Chichinales Formation, Río Negro Province. The degree of faunistic differentiation between these probably synchronous units could be a result of local palaeoenvironmental differences
How to do empirical economics
Francis Kramarz,Joshua D. Angrist,David M. Blau,Armin Falk
Investigaciones Económicas , 2006,
Abstract: Este artículo presenta una discusión entre economistas de primera línea acerca de cómo realizar investigación empírica en economía. Los participantes presentan los motivos que les llevan a elegir un proyecto, la construcción de bases de datos, los métodos que emplean, el papel de la teoría y su visión sobre los principales enfoques empíricos alternativos. El artículo finaliza con una discusión sobre un conjunto de artículos que representan modelos a seguir en la investigación aplicada.
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