202 research outputs found
A POLÍTICA COMO MOVIMENTO INDUTOR DO TRABALHO COLETIVO NAS ESCOLAS: O PROCESSO SINGULAR DE IMPLEMENTAÇÃO DA LEI FEDERAL 11.738/2008 NO MUNICÍPIO DE CURITIBA
O pressuposto subjacente à construção deste trabalho acentua a capacidade do ente federado municipal em responder de modo singular às demandas inscritas na agenda nacional a partir das lacunas que circunscrevem o campo das políticas públicas e potencializam as disputas pelos distintos significados que assumem a produção das soluções para o problema posto na agenda. Nesse ínterim, intenta-se explicitar o modo peculiar de resposta dada pela Secretaria Municipal da Educação de Curitiba à demanda nacional de ampliação do tempo destinado à hora-atividade - prevista na Lei Federal 11.738/2008 (Lei do Piso). Aspecto indelével na análise deste trabalho diz respeito ao princípio da simultaneidade existente entre os distintos lócus de produção e significação das políticas. Destarte, a despeito dos movimentos contrários, dos obstáculos e das contradições próprias da movimentação política, o município de Curitiba elaborou um novo projeto de organização escolar, o qual potencializou pedagogicamente os preceitos legais da Lei Federal do Piso Nacional no que tange à hora-atividade, ressignificando a Permanência e induzindo o trabalho coletivo no interior das escolas. Este movimento político de reinterpretação e ressignificação da demanda local frente a uma determinada política nacional, foi analisado e sistematizado neste trabalho a partir dos pressupostos teóricos da Abordagem Sequencial. Palavras-chave: Política. Poder. Hora-atividade. Hora permanência. Trabalho coletivo. Lei do Piso Salarial Nacional.
Irreversible Adsorption from Dilute Polymer Solutions
We study irreversible polymer adsorption from dilute solutions theoretically.
Universal features of the resultant non-equilibrium layers are predicted. Two
cases are considered, distinguished by the value of the local monomer-surface
sticking rate Q: chemisorption (very small Q) and physisorption (large Q).
Early stages of layer formation entail single chain adsorption. While single
chain physisorption times tau_ads are typically microsecs, for chemisorbing
chains of N units we find experimentally accessible times tau_ads = Q^{-1}
N^{3/5}, ranging from secs to hrs. We establish 3 chemisorption universality
classes, determined by a critical contact exponent: zipping, accelerated
zipping and homogeneous collapse. For dilute solutions, the mechanism is
accelerated zipping: zipping propagates outwards from the first attachment,
accelerated by occasional formation of large loops which nucleate further
zipping. This leads to a transient distribution omega(s) \sim s^{-7/5} of loop
lengths s up to a size s_max \approx (Q t)^{5/3} after time t. By tau_ads the
entire chain is adsorbed. The outcome of the single chain adsorption episode is
a monolayer of fully collapsed chains. Having only a few vacant sites to adsorb
onto, late arriving chains form a diffuse outer layer. In a simple picture we
find for both chemisorption and physisorption a final loop distribution
Omega(s) \sim s^{-11/5} and density profile c(z) \sim z^{-4/3} whose forms are
the same as for equilibrium layers. In contrast to equilibrium layers, however,
the statistical properties of a given chain depend on its adsorption time; the
outer layer contains many classes of chain, each characterized by different
fraction of adsorbed monomers f. Consistent with strong physisorption
experiments, we find the f values follow a distribution P(f) \sim f^{-4/5}.Comment: 18 pages, submitted to Eur. Phys. J. E, expanded discussion sectio
Single-balloon enteroscopy: results from an initial experience at a U.S. tertiary-care center
Single Balloon Enteroscopy (SBE) is a novel deep enteroscopy modality for diagnosis and treatment of disorders of the small bowel
The role of Networking Capabilities During the Covid-19 Crisis: Lessons Learned From SMEs in an Emerging Market
This paper aims to analyze how small and medium enterprises (SMEs) used their networking capabilities (NC) to initiate, develop, and terminate business relationships to reduce the negative impacts of the Covid-19 crisis. This study followed a qualitative approach and investigated six SMEs purposely selected based on the study’s requirement. Data were obtained through internet searches and 13 interviews with firm owners and top managers from the SMEs. Our findings show six lessons regarding the role of NC’s during the Covid-19 crisis. The lessons address topics such as starting collaborative partnerships, open communication between companies, among others. These lessons are useful for minimizing economic crisis impacts and managing inter-organizational relations during crisis periods
Facultative Symbiont Infections Affect Aphid Reproduction
Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproduction alternate within the annual life cycle. Many species, including the pea aphid, also show variation in their reproductive mode at the population level, with some lineages reproducing by cyclical parthenogenesis and others by permanent parthenogenesis. While the role of facultative symbionts has been well studied during the parthenogenetic phase of their aphid hosts, very little is known on their possible influence during the sexual phase. Here we investigated whether facultative symbionts modulate the capacity to produce sexual forms in various genetic backgrounds of the pea aphid with controlled symbiont composition and also in different aphid genotypes from natural populations with previously characterized infection status and reproductive mode. We found that most facultative symbionts exhibited detrimental effects on their hosts fitness under sex-inducing conditions in comparison with the reference lines. We also showed that the loss of sexual phase in permanently parthenogenetic lineages of A. pisum was not explained by facultative symbionts. Finally, we demonstrated that Spiroplasma infection annihilated the production of males in the host progeny by inducing a male-killing phenotype, an unexpected result for organisms such as aphids that reproduce primarily through clonal reproduction
Incidence, management, and outcomes of cardiovascular insufficiency in critically ill term and late preterm newborn infants
OBJECTIVE:
The objective of this study was to characterize the incidence, management, and short-term outcomes of cardiovascular insufficiency (CVI) in mechanically ventilated newborns, evaluating four separate prespecified definitions.
STUDY DESIGN:
Multicenter, prospective cohort study of infants ≥34 weeks gestational age (GA) and on mechanical ventilation during the first 72 hours. CVI was prospectively defined as either (1) mean arterial pressure (MAP) < GA; (2) MAP < GA + signs of inadequate perfusion; (3) any therapy for CVI; or (4) inotropic therapy. Short-term outcomes included death, days on ventilation, oxygen, and to full feedings and discharge.
RESULTS:
Of 647 who met inclusion criteria, 419 (65%) met ≥1 definition of CVI. Of these, 98% received fluid boluses, 36% inotropes, and 17% corticosteroids. Of treated infants, 46% did not have CVI as defined by a MAP < GA ± signs of inadequate perfusion. Inotropic therapy was associated with increased mortality (11.1 vs. 1.3%; p < 0.05).
CONCLUSION:
More than half of the infants met at least one definition of CVI. However, almost half of the treated infants met none of the definitions. Inotropic therapy was associated with increased mortality. These findings can help guide the design of future studies of CVI in newborn
Establishing Alpha Oph as a Prototype Rotator: Improved Astrometric Orbit
The nearby star Alpha Oph (Ras Alhague) is a rapidly rotating A5IV star
spinning at ~89% of its breakup velocity. This system has been imaged
extensively by interferometric techniques, giving a precise geometric model of
the star's oblateness and the resulting temperature variation on the stellar
surface. Fortuitously, Alpha Oph has a previously known stellar companion, and
characterization of the orbit provides an independent, dynamically-based check
of both the host star and the companion mass. Such measurements are crucial to
constrain models of such rapidly rotating stars. In this study, we combine
eight years of Adaptive Optics imaging data from the Palomar, AEOS, and CFHT
telescopes to derive an improved, astrometric characterization of the companion
orbit. We also use photometry from these observations to derive a model-based
estimate of the companion mass. A fit was performed on the photocenter motion
of this system to extract a component mass ratio. We find masses of
2.40^{0.23}_{0.37} solar masses and 0.85^{0.06}_{0.04} solar masses for Alpha
Oph A and Alpha Oph B, respectively. Previous orbital studies of this system
found a mass too high for this system, inconsistent with stellar evolutionary
calculations. Our measurements of the host star mass are more consistent with
these evolutionary calculations, but with slightly higher uncertainties. In
addition to the dynamically-derived masses, we use IJHK photometry to derive a
model-based mass for Alpha Oph B, of 0.77 +/- 0.05 solar masses marginally
consistent with the dynamical masses derived from our orbit. Our model fits
predict a periastron passage on 2012 April 19, with the two components having a
~50 milliarcsec separation from March to May 2012. A modest amount of
interferometric and radial velocity data during this period could provide a
mass determination of this star at the few percent level.Comment: Accepted to ApJ, 6 pages, 4 figure
Rapid buildup of sympatric species diversity in Alpine whitefish
Adaptive radiations in postglacial fish offer excellent settings to study the evolutionary
mechanisms involved in the rapid buildup of sympatric species diversity from a single lineage. Here, we address this by exploring the genetic and ecological structure of the largest Alpine whitefish radiation known, that of Lakes Brienz and Thun, using microsatellite data of more than 2000 whitefish caught during extensive species-targeted
and habitat-randomized fishing campaigns. We find six strongly genetically and
ecologically differentiated species, four of which occur in both lakes, and one of which
was previously unknown. These four exhibit clines of genetic differentiation that are
paralleled in clines of eco-morphological and reproductive niche differentiation, consistent
with models of sympatric ecological speciation along environmental gradients.
In Lake Thun, we find two additional species, a profundal specialist and a species introduced in the 1930s from another Alpine whitefish radiation. Strong genetic differentiation between this introduced species and all native species of Lake Thun suggests that reproductive isolation can evolve among allopatric whitefish species within
15,000 years and persist in secondary sympatry. Consistent with speciation theory,
we find stronger correlations between genetic and ecological differentiation for sympatrically than for allopatrically evolved species
Rhodolith Beds Are Major CaCO3 Bio-Factories in the Tropical South West Atlantic
Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (<150 m depth) subjected to episodic disturbance. Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N - 27°S). To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50′ - 19°45′S) off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km2. Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO3 production was estimated from in situ growth assays at 1.07 kg m−2 yr−1, with a total production rate of 0.025 Gt yr−1, comparable to those of the world's largest biogenic CaCO3 deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades
Age-dependent effects of low-dose nicotine treatment on cocaine-induced behavioral plasticity in rats
Epidemiological evidence of early adolescent tobacco use, prior to that of marijuana and other illicit drugs, has led to the hypothesis that nicotine is a “gateway” drug that sensitizes reward pathways to the addictive effects of other psychostimulants.
To test this hypothesis, we have compared the effect of a brief, low-dose nicotine pretreatment of adolescent and adult rats on subsequent locomotor response to acute and chronic cocaine.
Adolescents, aged postnatal day (P) 28, and adults, aged P86, were given four daily injections of saline or nicotine (0.06 mg/kg, i.v.). At P32 and P90, rats were given acute injections of cocaine (0, 0.4 or 1.0 mg/kg, i.v.) and monitored for locomotor activity in either a habituated or novel test environment. To examine cocaine sensitization, rats were treated for 3 days with saline or cocaine (0.4 mg/kg, i.v.), and, after 1 day of withdrawal, were given a challenge dose of cocaine (0.4 mg/kg, i.v.).
Nicotine pretreatment did not affect acute, drug-induced locomotor activity at either age. However, age differences in cocaine response were observed, with adolescent animals showing enhanced locomotor activity in the novel environment. Adolescent controls did not exhibit cocaine-induced locomotor sensitization, whereas adults did. Nicotine pretreatment during adolescence promoted the development and expression of a sensitized response to repeated cocaine exposure similar to that observed in saline-pretreated adult controls.
These findings show that brief pretreatment with nicotine, in a low dose comparable to that inhaled in 2–4 cigarettes, enhances cocaine-induced behavioral plasticity in adolescent rats
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