The Effect of Degree Attainment on Arrests: Evidence from a Randomized Social Experiment

We examine the effect of educational attainment on criminal behavior using random assignment into Job Corps (JC) – the United States' largest education and vocational training program for disadvantaged youth – as a source of exogenous variability in educational attainment. We allow such random assignment to violate the exclusion restriction when used as an instrument by employing nonparametric bounds. The attainment of a degree is estimated to reduce arrest rates by at most 11.8 percentage points (about 32.6%). We also find suggestive evidence that the effects may be larger for males relative to females, and larger for black males relative to white males. Remarkably, our 95 percent confidence intervals on the causal effect of education on arrests are very similar to the corresponding confidence intervals on the same effect from studies exploiting changes in compulsory schooling laws as an instrumental variable in the estimation of the effect of education on arrest rates (e.g., Lochner and Moretti, 2004)

Methane activation and exchange by titanium-carbon multiple bonds

We demonstrate that a titanium-carbon multiple bond, specifically an alkylidyne ligand in the transient complex, (PNP)Ti≡C^(t)Bu (A) (PNP^− = N[2-P(CHMe_2)_(2)-4-methylphenyl]_2), can cleanly activate methane at room temperature with moderately elevated pressures to form (PNP)Ti=CHtBu(CH_3). Isotopic labeling and theoretical studies suggest that the alkylidene and methyl hydrogens exchange, either via tautomerization invoking a methylidene complex, (PNP)Ti=CH_(2)(CH_(2)^(t)Bu), or by forming the methane adduct (PNP)Ti≡C^(t)Bu(CH_4). The thermal, fluxional and chemical behavior of (PNP)Ti=CH^(t)Bu(CH_3) is also presented in this study

Monitoring Backbone Hydrogen-Bond Formation in β-Barrel Membrane Protein Folding

β-barrel membrane proteins are key components of the outer membrane of bacteria, mitochondria and chloroplasts. Their three-dimensional structure is defined by a network of backbone hydrogen bonds between adjacent β-strands. Here, we employ hydrogen-deuterium (H/D) exchange in combination with NMR spectroscopy and mass spectrometry to monitor backbone hydrogen bond formation during folding of the outer membrane protein X (OmpX) from E. coli in detergent micelles. Residue-specific kinetics of interstrand hydrogen-bond formation were found to be uniform in the entire β-barrel and synchronized to formation of the tertiary structure. OmpX folding thus propagates via a long-lived conformational ensemble state in which all backbone amide protons exchange with the solvent and engage in hydrogen bonds only transiently. Stable formation of the entire OmpX hydrogen bond network occurs downhill of the rate-limiting transition state and thus appears cooperative on the overall folding time scale

Probing the cosmic star formation using long Gamma-Ray Bursts: New constraints from the Spitzer Space Telescope

We report on IRAC-4.5mic, IRAC-8.0mic and MIPS-24mic deep observations of 16 Gamma-Ray Burst (GRBs) host galaxies performed with the Spitzer Space Telescope, and we investigate in the thermal infrared the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with these objects. Our sample is derived from GRBs that were identified with sub-arcsec localization between 1997 and 2001, and only a very small fraction (~20%) of the targeted sources is detected down to f_4.5mic ~3.5microJy and f_24mic ~85microJy (3sigma). This likely argues against a population dominated by massive and strongly-starbursting (i.e., SFR > ~100 Msol/yr) galaxies as it has been recently suggested from submillimeter/radio and optical studies of similarly-selected GRB hosts. Furthermore we find evidence that some GRBs do not occur in the most infrared-luminous regions -- hence the most actively star-forming environments -- of their host galaxies. Should the GRB hosts be representative of all star-forming galaxies at high redshift, models of infrared galaxy evolution indicate that > ~50% of GRB hosts should have f_24mic > ~100microJy. Unless the identification of GRBs prior to 2001 was prone to strong selection effects biasing our sample against dusty galaxies, we infer in this context that the GRBs identified with the current techniques can not be directly used as unbiased probes of the global and integrated star formation history of the Universe.Comment: ApJ in press, 23 pages, 8 figures (scheduled for the ApJ 10 May 2006, v642 2 issue). Full resolution available at http://perceval.as.arizona.edu/~elefloch/Publis/ms_grb_spitzer.pd

Privatización: ¿Suben o bajan los precios? Duopolio mixto con diferenciación vertical

In this paper, we use a duopoly model with vertical (quality) product differentiation to determine whether privatization of a public firm leads to higher or lower prices than those prevailing in a mixed duopoly. We show that privatization can move prices on either direction.

Complex pattern of interaction between in utero hypoxia-ischemia and intra-amniotic inflammation disrupts brain development and motor function

Background: Infants born preterm commonly suffer from a combination of hypoxia-ischemia (HI) and infectious perinatal inflammatory insults that lead to cerebral palsy, cognitive delay, behavioral issues and epilepsy. Using a novel rat model of combined late gestation HI and lipopolysaccharide (LPS)-induced inflammation, we tested our hypothesis that inflammation from HI and LPS differentially affects gliosis, white matter development and motor impairment during the first postnatal month. Methods: Pregnant rats underwent laparotomy on embryonic day 18 and transient systemic HI (TSHI) and/or intra-amniotic LPS injection. Shams received laparotomy and anesthesia only. Pups were born at term. Immunohistochemistry with stereological estimates was performed to assess regional glial loads, and western blots were performed for protein expression. Erythropoietin ligand and receptor levels were quantified using quantitative PCR. Digigait analysis detected gait deficits. Statistical analysis was performed with one-way analysis of variance and post-hoc Bonferonni correction. Results: Microglial and astroglial immunolabeling are elevated in TSHI + LPS fimbria at postnatal day 2 compared to sham (both P < 0.03). At postnatal day 15, myelin basic protein expression is reduced by 31% in TSHI + LPS pups compared to shams (P < 0.05). By postnatal day 28, white matter injury shifts from the acute injury pattern to a chronic injury pattern in TSHI pups only. Both myelin basic protein expression (P < 0.01) and the phosphoneurofilament/neurofilament ratio, a marker of axonal dysfunction, are reduced in postnatal day 28 TSHI pups (P < 0.001). Erythropoietin ligand to receptor ratios differ between brains exposed to TSHI and LPS. Gait analyses reveal that all groups (TSHI, LPS and TSHI + LPS) are ataxic with deficits in stride, paw placement, gait consistency and coordination (all P < 0.001). Conclusions: Prenatal TSHI and TSHI + LPS lead to different patterns of injury with respect to myelination, axon integrity and gait deficits. Dual injury leads to acute alterations in glial response and cellular inflammation, while TSHI alone causes more prominent chronic white matter and axonal injury. Both injuries cause significant gait deficits. Further study will contribute to stratification of injury mechanisms in preterm infants, and guide the use of promising therapeutic interventions

Determinação de cronograma de manutenção preventiva utilizando algoritmo genético

Este artigo propõe um método para otimização do cronograma de manutenção preventiva com vistas à minimização dos custos associados. Dados de falhas são coletados e modelados através de distribuições de probabilidades paramétricas. Na sequência, geram-se índices de melhoria associados aos incrementos de confiabilidade decorrentes das manutenções, valendo-se do conhecimento de especialistas de processo, conforme Tsai et al. (2001). Tais índices são integrados a formulações quantificadoras do custo incorrido pelos procedimentos de manutenção. A formulação é otimizada através de Algoritmo Genético (AG), determinando o melhor tipo de manutenção (por exemplo, manutenção total ou parcial) a ser realizada em intervalos pré-definidos. Ao ser aplicado em uma máquina de transformação de bobinas de aço plano em tubos, o método gerou um cronograma coerente de manutenções com base na avaliação de especialistas de processo, além de reduzir em 20% os custos comparados à programação empírica de manutenção. Os resultados ainda comprovam a eficiência de AGs na resolução de problemas de manutenção por conta de sua rápida convergência e fácil implementação

A shared neural ensemble links distinct contextual memories encoded close in time.

Recent studies suggest that a shared neural ensemble may link distinct memories encoded close in time. According to the memory allocation hypothesis, learning triggers a temporary increase in neuronal excitability that biases the representation of a subsequent memory to the neuronal ensemble encoding the first memory, such that recall of one memory increases the likelihood of recalling the other memory. Here we show in mice that the overlap between the hippocampal CA1 ensembles activated by two distinct contexts acquired within a day is higher than when they are separated by a week. Several findings indicate that this overlap of neuronal ensembles links two contextual memories. First, fear paired with one context is transferred to a neutral context when the two contexts are acquired within a day but not across a week. Second, the first memory strengthens the second memory within a day but not across a week. Older mice, known to have lower CA1 excitability, do not show the overlap between ensembles, the transfer of fear between contexts, or the strengthening of the second memory. Finally, in aged mice, increasing cellular excitability and activating a common ensemble of CA1 neurons during two distinct context exposures rescued the deficit in linking memories. Taken together, these findings demonstrate that contextual memories encoded close in time are linked by directing storage into overlapping ensembles. Alteration of these processes by ageing could affect the temporal structure of memories, thus impairing efficient recall of related information

An evaluation of peri-implant marginal bone loss according to implant type, surgical technique and prosthetic rehabilitation: a retrospective multicentre and cross-sectional cohort study

To evaluate implant loss (IL) and marginal bone loss (MBL); follow-up period of up to 10 years after prosthetic loading. Retrospective multi-centre cross-sectional cohort study. Double analysis: (1) all the implants (n = 456) were analysed; (2) to allow for possible cluster error, one implant per patient (n = 143) was selected randomly. Statistical analysis: Spearman's correlation coefficient; Kruskal-Wallis (post-hoc U-Mann-Whitney); Chi-square (post-hoc Haberman). (1) Analysing all the implants (456): IL was observed in patients with past periodontitis (6 vs. 2.2%, p < 0.05), short implants (12 vs. 2.8%, p < 0.001) and when using regenerative surgery (11.3 vs. 2.9%, p < 0.001); greater MBL was observed among smokers (0.39 ± 0.52 vs. 0.2 ± 0.29, p < 0.01), maxillary implants (0.28 ± 0.37 vs. 0.1 ± 0.17, p < 0.0001), anterior region implants (0.32 ± 0.36 vs. 0.21 ± 0.33, p < 0.001), external connection implants (0.2 ± 0.29 vs. 0.63 ± 0.59, p < 0.0001), and 2-3 years after loading (p < 0.0001). (2) analysing the cluster (143): IL was observed in smokers (18.8 vs. 3.5%, p < 0.05), splinted fixed crowns (12.9%, p < 0.01), short implants (22.2 vs. 4.0%, p < 0.01) and when using regenerative surgery (19.2 vs. 3.4%, p < 0.01); greater MBL was observed in maxillary implants (0.25 ± 0.35 vs. 0.11 ± 0.18, p < 0.05), in the anterior region (p < 0.05), in the first 3 years (p < 0.01), in external connection implants (0.72 ± 0.71 vs. 0.19 ± 0.26, p < 0.01) and in short implants (0.38 ± 0.31 vs. 0.2 ± 0.32, p < 0.05). There is greater risk in smokers, patients with past periodontal disease, external connection implants, the use of short implants and when regenerative techniques are used. To prevent MBL and IL, implantologists should be very meticulous in indicating implants in patients affected by these host factors

ζ1 + ζ2 Reticuli binary system: a puzzling chromospheric activity pattern

We perform, for the first time, a detailed long-term activity study of the binary system ζ Ret. We use all available HARPS spectra obtained between the years 2003 and 2016. We build a time series of the Mount Wilson S index for both stars, then we analyse these series by using Lomb-Scargle periodograms. The components ζ1 Ret and ζ2 Ret that belong to this binary system are physically very similar to each other and also similar to our Sun, which makes it a remarkable system. We detect in the solar-analogue star ζ2 Ret a long-term activity cycle with a period of ?10 yr, similar to the solar one (?11 yr). It is worthwhile to mention that this object satisfies previous criteria for a flat star and for a cycling star simultaneously. Another interesting feature of this binary system is a high ?0.220 dex difference between the average log (R^´ }_HK) activity levels of both stars. Our study clearly shows that ζ1 Ret is significantly more active than ζ2 Ret. In addition, ζ1 Ret shows an erratic variability in its stellar activity. In this work, we explore different scenarios trying to explain this rare behaviour in a pair of coeval stars, which could help to explain the difference in this and other binary systems. From these results, we also warn that for the development of activity-age calibrations (which commonly use binary systems and/or stellar clusters as calibrators) the whole history of activity available for the stars involved should be taken into account.Fil: Flores, M. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Saffe, Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Buccino, Andrea Paola. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Jaque Arancibia, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: González, J F. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Nuñez, N E. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Jofré, E. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentin