Directed Light Fabrication of Iron-Based Materials

Directed light fabrication (DLF) is a process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, 3-dimensional metal components. From a computer generated solid model, deposition ``tool paths`` are constructed that command the laser movement to fabricate near net shape parts a layer at a time. Among potential candidate systems to study, iron-based alloys are particularly attractive for rapid prototyping. To evaluate the processing parameters in the DLF process, studies have been performed on the microstructural development in 1-dimensional and 2-dimensional Fe-based components. For example, continuous microstructural features are evident, implying a continuous liquid/solid interface during processing. In addition, solidification cooling rates have been determined based upon secondary dendrite arm spacings in Fe-25wt. % Ni and 316 stainless steel. Cooling rates vary from 10{sup 1}{minus}10{sup 5} K s{sup {minus}1}, and the solidification behavior has been simulated using macroscopic heat transfer analyses

Data Leakage in Notebooks: Static Detection and Better Processes

Data science pipelines to train and evaluate models with machine learning may contain bugs just like any other code. Leakage between training and test data can lead to overestimating the model's accuracy during offline evaluations, possibly leading to deployment of low-quality models in production. Such leakage can happen easily by mistake or by following poor practices, but may be tedious and challenging to detect manually. We develop a static analysis approach to detect common forms of data leakage in data science code. Our evaluation shows that our analysis accurately detects data leakage and that such leakage is pervasive among over 100,000 analyzed public notebooks. We discuss how our static analysis approach can help both practitioners and educators, and how leakage prevention can be designed into the development process

Winter Movements of Bowhead Whales (Balaena mysticetus) in the Bering Sea

Working with subsistence whale hunters, we tagged bowhead whales (Balaena mysticetus) with satellite-linked transmitters and documented their movements in the Bering Sea during two winters. We followed 11 whales through the winter of 2008 – 09 and 10 whales in 2009 – 10. The average date that bowhead whales entered the Bering Sea was 14 December in 2008 and 26 November in 2009. All but one tagged whale entered the Bering Sea west of Big Diomede Island. In the winter of 2008 – 09, whales were distributed in a line extending from the Bering Strait to Cape Navarin, whereas in 2009 – 10, the distribution shifted south of St. Lawrence Island, extending from Cape Navarin to St. Matthew Island. Bowhead whales were most likely to be found in areas with 90% – 100% sea-ice concentration and were generally located far from the ice edge and polynyas. The average date whales left the Bering Sea was 12 April in 2009 and 22 April in 2010. During the spring migration, all whales but one traveled north along the Alaska coast to summering grounds in the Canadian Beaufort. The remaining whale migrated a month later and traveled up the northern coast of Chukotka, where it was located when the tag stopped transmitting in August. It is unlikely that this whale migrated to the Beaufort Sea before returning south to winter within the Bering Sea, indicating the movements of bowhead whales are more complex than generally believed. Declining sea ice in the Bering Sea may result in the expansion of commercial fisheries and shipping; areas where such activities may overlap the winter range of bowhead whales include the Bering and Anadyr straits, the eastern edge of Anadyr Bay, and St. Matthew Island.Avec l’aide de pêcheurs de baleine de subsistance, nous avons marqué des baleines boréales (Balaena mysticetus) au moyen de transmetteurs en liaison avec un satellite et répertorié leurs mouvements au cours de deux hivers dans la mer de Béring. Nous avons suivi 11 baleines pendant l’hiver 2008-2009 et dix baleines en 2009-2010. En 2008, les baleines boréales sont entrées dans la mer de Béring le 14 décembre en moyenne, tandis qu’en 2009, elles sont arrivées le 26 novembre. À l’exception d’une baleine, toutes les baleines marquées ayant pénétré dans la mer de Béring sont passées par l’ouest de la grande île Diomède. À l’hiver 2008-2009, le parcours des baleines s’étendait en ligne depuis le détroit de Béring jusqu’au cap Navarin, tandis qu’en 2009-2010, le parcours s’est déplacé vers le sud de l’île Saint-Laurent, s’étendant ainsi du cap Navarin jusqu’à l’île Saint-Mathieu. Les baleines boréales étaient plus susceptibles de se retrouver dans les endroits dont la glace de mer a une concentration allant de 90 à 100 %. Généralement, elles se tiennent loin des lisières de glace et des polynies. En 2009, la date moyenne à laquelle les baleines ont quitté la mer de Beaufort était le 12 avril, tandis qu’en 2010, cette date était le 22 avril. Pendant la migration printanière, toutes les baleines, sauf une, se sont déplacées vers le nord le long de la côte de l’Alaska pour se rendre à leur aire d’estivage dans la partie canadienne de Beaufort. L’autre baleine a fait sa migration un mois plus tard et s’est déplacée le long de la côte nord de Tchoukotka, là où elle avait été repérée lorsque son marqueur a cessé ses transmissions en août. Il est improbable que cette baleine ait migré dans la mer de Beaufort avant de revenir vers le sud pour passer l’hiver dans la mer de Béring, ce qui indique que les mouvements des baleines boréales sont plus complexes qu’on ne le croyait antérieurement. La perte de glace de mer dans la mer de Béring pourrait se traduire par l’intensification des activités de pêche commerciale et d’expédition de marchandises. Les endroits où ces activités pourraient chevaucher le parcours d’hiver des baleines boréales comprennent les détroits de Béring et d’Anadyr, le côté est de la baie d’Anadyr et l’île Saint-Mathieu

Nonequilibrium dynamics of strings in time-dependent plane wave backgrounds

We formulate and study the nonequilibrium dynamics of strings near the singularity of the time-dependent plane wave background in the framework of the Nonequilibrium Thermo Field Dynamics (NETFD). In particular, we construct the Hilbert space of the thermal string oscillators at nonequilibrium and generalize the NETFD to describe the coordinates of the center of mass of the thermal string. The equations of motion of the thermal fields and the Hamiltonian are derived. Due to the time-dependence of the oscillator frequencies, a counterterm is present in the Hamiltonian. This counterterm determines the correlation functions in a perturbative fashion. We compute the two point correlation function of the thermal string at zero order in the power expansion.Comment: 21 page

La geoquímica de la Formación Maimón (Cordillera Central, República Dominicana) revisada

Los materiales volcánicos de la Formación Maimón, metamorfizados en facies de esquistos verdes, son representativos del magmatismo más antiguo registrado en el arco-isla del Cretácico del Caribe. A partir de nuevos datos geoquímicos de roca total y mediante el uso de elementos traza inmóviles (elementos de alto potencial iónico - HFSE, tierras raras - REE), se reconoce el predominio de protolitos basálticos y una menor proporción de rocas de composición intermedia y ácida. Geoquímicamente, los protolitos basálticos han sido clasificados como boninitas, toleítas de arco de isla pobres en Ti y LREE, toleítas de arco de isla pobres en Ti normales y escasas toleítas de arco de isla normales. Las rocas ácidas presentan claras afinidades boniníticas y toleíticas y pertenecerían al tipo M (derivadas del manto). La geoquímica de las toleítas pobres en Ti y LREE permite su clasificación como FAB (Fore-Arc Basalts, i.e. basaltos de ante-arco), término recientemente acuñado para describir toleítas con rasgos de MORB (basaltos de dorsal centro-oceánica) identificados en el ante-arco de Izu-Bonin-Mariana. La presencia de FAB y su correlación estratigráfica con boninitas son indicativas de formación en un contexto de ante-arco durante los primeros estadios magmáticos en un régimen extensional ligado al inicio de la subducción y el nacimiento del arco-isla. La Fm. Maimón puede representar la sección superior (volcánica) de una ofiolita tipo "inicio de subducción"

Phylogeny of Diving Beetles Reveals a Coevolutionary Arms Race between the Sexes

BACKGROUND: Darwin illustrated his sexual selection theory with male and female morphology of diving beetles, but maintained a cooperative view of their interaction. Present theory suggests that instead sexual conflict should be a widespread evolutionary force driving both intersexual coevolutionary arms races and speciation. METHODOLOGY/PRINCIPAL FINDINGS: We combined Bayesian phylogenetics, complete taxon sampling and a multi-gene approach to test the arms race scenario on a robust diving beetle phylogeny. As predicted, suction cups in males and modified dorsal surfaces in females showed a pronounced coevolutionary pattern. The female dorsal modifications impair the attachment ability of male suction cups, but each antagonistic novelty in females corresponds to counter-differentiation of suction cups in males. CONCLUSIONS: A recently diverged sibling species pair in Japan is possibly one consequence of this arms race and we suggest that future studies on hypoxia might reveal the key to the extraordinary selection for female counter-adaptations in diving beetles

Profiling cytotoxic microRNAs in pediatric and adult glioblastoma cells by high-content screening, identification, and validation of miR-1300

MicroRNAs play an important role in the regulation of mRNA translation and have therapeutic potential in cancer and other diseases. To profile the landscape of microRNAs with significant cytotoxicity in the context of glioblastoma (GBM), we performed a high-throughput screen in adult and pediatric GBM cells using a synthetic oligonucleotide library representing all known human microRNAs. Bioinformatics analysis was used to refine this list and the top seven microRNAs were validated in a larger panel of GBM cells using state-of-the-art in vitro assays. The cytotoxic effect of our most relevant candidate was assessed in a preclinical model. Our screen identified ~100 significantly cytotoxic microRNAs with 70% concordance between cell lines. MicroRNA-1300 (miR-1300) was the most potent and robust candidate. We observed a striking binucleated phenotype in miR-1300 transfected cells due to cytokinesis failure followed by apoptosis. This was also observed in two stem-like patient-derived cultures. We identified the physiological role of miR-1300 as a regulator of endomitosis in megakaryocyte differentiation where blockade of cytokinesis is an essential step. In GBM cells, where miR-1300 is normally not expressed, the oncogene Epithelial Cell Transforming 2 (ECT2) was validated as a direct key target. ECT2 siRNA phenocopied the effects of miR-1300, and ECT2 overexpression led to rescue of miR-1300 induced binucleation. We showed that ectopic expression of miR-1300 led to decreased tumor growth in an orthotopic GBM model. Our screen provides a resource for the neuro-oncology community and identified miR-1300 as a novel regulator of endomitosis with translatable potential for therapeutic application

Newborn Sequencing in Genomic Medicine and Public Health

The rapid development of genomic sequencing technologies has decreased the cost of genetic analysis to the extent that it seems plausible that genome-scale sequencing could have widespread availability in pediatric care. Genomic sequencing provides a powerful diagnostic modality for patients who manifest symptoms of monogenic disease and an opportunity to detect health conditions before their development. However, many technical, clinical, ethical, and societal challenges should be addressed before such technology is widely deployed in pediatric practice. This article provides an overview of the Newborn Sequencing in Genomic Medicine and Public Health Consortium, which is investigating the application of genome-scale sequencing in newborns for both diagnosis and screening

The Role of Task and Process Conflict in Strategizing

The implementation of strategic initiatives is central to organizational success because it involves not just the execution of strategy, but also the formulation of strategy content. Yet, strategy implementation is complex, partially because it is critically affected by human dynamics. These dynamics are an integral but poorly understood aspect of how organizations negotiate multiple goals. Conflict is one dynamic that has received little attention in the context of strategy implementation. The authors address this gap by studying task and process conflict as a firm implements a strategy in real time. The study demonstrates that process conflict directs attention to problems with how to implement a strategy, while task conflict directs attention to problems with the content of the strategy. Critically, however, managers can only harness generative effects of conflict if they correctly diagnose process and task conflict, and respond to both forms of conflict. This requires an understanding of the entwined nature of task and process conflict, and highlights the necessity of aligning responses to these forms of conflict. Thus, this study offers conflict as one explanatory mechanism of how actors execute strategy and clarify strategy content