"Hard Times, Easy Money? Countercyclical Stabilization in an Uncertain Economy"

The tools of countercyclical monetary policy have been brought fully to bear on a potentially severe recession. This note argues, however, that such a policy is less effective in times such as these--that is, when uncertainty is especially high--and so is likely to be particularly ineffective in combating the current economic slowdown.

Investment behavior, observable expectations, and internal funds: a comment on Cummins et al. (AER, 2006)

Cummins et al. (2006) construct a new measure of fundamentals, and show that the positive cash flow effects typically found in investment-Q models disappear when traditional Q is replaced with their new measure. Their results are not robust to small changes in their specification or in the dataset used to estimate their model. The explanatory power of cash flow does not disappear when replacing traditional Q with their new measure of Q it is never there to begin with. Investment's lack of sensitivity to cash flow may be because their data is biased towards firms with positive cash flow (it is negative for only 242 observations of 11431). This bias and our results mute their argument that the positive cash-flow effects obtained in such models may reflect a failure to control properly for fundamentals rather than the presence of financial constraints.

Investment behavior, observable expectations, and internal funds: a comment on Cummins et al. (AER, 2006)

Cummins et al. (2006) construct a new measure of fundamentals, and show that the positive cash flow effects typically found in investment-Q models disappear when traditional Q is replaced with their new measure. Their results are not robust to small changes in their specification or in the dataset used to estimate their model. The explanatory power of cash flow does not disappear when replacing traditional Q with their new measure of Q; it is never there to begin with. Investment’s lack of sensitivity to cash flow may be because their data is biased towards firms with positive cash flow (it is negative for only 242 observations of 11431). This bias and our results mute their argument that the positive cash-flow effects obtained in such models may reflect a failure to control properly for fundamentals rather than the presence of financial constraints.Investment, Cash flow, Financial constraints.

Italian Corporate Governance, Investment, and Finance

Italian industrial structure and financial markets have several distinct features. Italian firms are relatively small, few trade publicly and no corporate bond market exists. The limited types of external funds available to Italian firms makes them prone to financing constraints. We examine a panel containing over 1100 Italian firms. We find that firm size does not appear correlated with the severity of financing constraints. We also find that small firms are frequently mature. Our results suggest that young firms face financing constraints, while mature firms may develop relationships with lenders that lower the costs of external funds. Small, young firms appear to face the tightest financing constraints. Many firms are affiliated with pyramidal business groups. We find that affiliation with pyramidal business groups appears to reduce the effect of financing constraints. Our results have important implications for government policy to promote small firm growth in Italy.

Decoding messages from the yield curve

Bank supervision ; Federal Reserve District, 5th

Inventory Investment, Internal-Finance Fluctuation, and the Business Cycle

macroeconomics, inventory investment, internal-finance fluctuation, business cycle

Estimación de edades arqueológicas usando la hidratación de obsidianas: dos fuentes de los andes meridionales

Obsidian is abundant in archaeological sites throughout Mendoza Province, Argentina but no obsidian hydration rates exist to date these assemblages. Direct dating of obsidian artifacts is particularly important in west-central Argentina because the surface record is extensive but well-defined time marker artifacts are lacking. The costs of non-optical hydration dating techniques currently preclude their regular use in the region, however. We present and evaluate 12 models for age estimation based on optical hydration rim measurements for the two most commonly used obsidian types in the region (Las Cargas and Laguna del Maule). Age estimation equations are derived for each source using observed hydration rim-radiocarbon date pairs, and parameterized by variables known to influence obsidian hydration in experimental settings. The equations advanced here are currently best at predicting the known ages of artifacts independently dated by radiocarbon, and can be cautiously used to estimate the ages of obsidian artifacts.Las obsidianas son abundantes en los sitios arqueológicos de la provincia de Mendoza (Argentina). Sin embargo, hasta el momento no existen estimaciones para las tasas de hidratación de estas rocas que puedan utilizarse para fechar esos conjuntos líticos. La realización de fechados directos sobre artefactos de obsidiana resulta particularmente importante para esta región, dado que existe un vasto registro arqueológico de superficie –compuesto principalmente por artefactos líticos– y solo se cuenta con tipos morfológicos cronológicamente sensibles para el Holoceno Tardío. Aquí se presentan y evalúan 12 modelos para estimar las edades de los artefactos de obsidiana basados en la medición óptica de los anillos de hidratación. Específicamente estos modelos fueron desarrollados para las dos obsidianas más comunes en los contextos arqueológicos de la región, procedentes de las fuentes de Las Cargas y Laguna del Maule. Las edades estimadas son derivadas para cada fuente a partir de pares de medición del espesor de la corteza de hidratación-fechado radiocarbono, y calibradas con variables cuya influencia sobre la hidratación ha sido establecida experimentalmente. Las ecuaciones que presentamos son actualmente las que mejor predicen las edades conocidas de artefactos que han sido fechados independientemente por radiocarbono y, por lo tanto, pueden utilizarse con cautela para estimar la antigüedad de los artefactos de obsidiana procedentes de la región.Fil: Garvey, Raven. University of Michigan; Estados UnidosFil: Carpenter, Tim. Archaeometrics; Estados UnidosFil: Gil, Adolfo Fabian. Universidad Nacional de Cuyo. Facultad de Filosofía y Letras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; ArgentinaFil: Neme, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; ArgentinaFil: Bettinger, Robert. University of California at Davis; Estados Unido

Identifying Interaction Sites in "Recalcitrant" Proteins: Predicted Protein and Rna Binding Sites in Rev Proteins of Hiv-1 and Eiav Agree with Experimental Data

Protein-protein and protein nucleic acid interactions are vitally important for a wide range of biological processes, including regulation of gene expression, protein synthesis, and replication and assembly of many viruses. We have developed machine learning approaches for predicting which amino acids of a protein participate in its interactions with other proteins and/or nucleic acids, using only the protein sequence as input. In this paper, we describe an application of classifiers trained on datasets of well-characterized protein-protein and protein-RNA complexes for which experimental structures are available. We apply these classifiers to the problem of predicting protein and RNA binding sites in the sequence of a clinically important protein for which the structure is not known: the regulatory protein Rev, essential for the replication of HIV-1 and other lentiviruses. We compare our predictions with published biochemical, genetic and partial structural information for HIV-1 and EIAV Rev and with our own published experimental mapping of RNA binding sites in EIAV Rev. The predicted and experimentally determined binding sites are in very good agreement. The ability to predict reliably the residues of a protein that directly contribute to specific binding events - without the requirement for structural information regarding either the protein or complexes in which it participates - can potentially generate new disease intervention strategies.Comment: Pacific Symposium on Biocomputing, Hawaii, In press, Accepted, 200

The Chlamydia trachomatis Type III Secretion Chaperone Slc1 Engages Multiple Early Effectors, Including TepP, a Tyrosine-phosphorylated Protein Required for the Recruitment of CrkI-II to Nascent Inclusions and Innate Immune Signaling

Chlamydia trachomatis, the causative agent of trachoma and sexually transmitted infections, employs a type III secretion (T3S) system to deliver effector proteins into host epithelial cells to establish a replicative vacuole. Aside from the phosphoprotein TARP, a Chlamydia effector that promotes actin re-arrangements, very few factors mediating bacterial entry and early inclusion establishment have been characterized. Like many T3S effectors, TARP requires a chaperone (Slc1) for efficient translocation into host cells. In this study, we defined proteins that associate with Slc1 in invasive C. trachomatis elementary bodies (EB) by immunoprecipitation coupled with mass spectrometry. We identified Ct875, a new Slc1 client protein and T3S effector, which we renamed TepP (Translocated early phosphoprotein). We provide evidence that T3S effectors form large molecular weight complexes with Scl1 in vitro and that Slc1 enhances their T3S-dependent secretion in a heterologous Yersinia T3S system. We demonstrate that TepP is translocated early during bacterial entry into epithelial cells and is phosphorylated at tyrosine residues by host kinases. However, TepP phosphorylation occurs later than TARP, which together with the finding that Slc1 preferentially engages TARP in EBs leads us to postulate that these effectors are translocated into the host cell at different stages during C.trachomatis invasion. TepP co-immunoprecipitated with the scaffolding proteins CrkI-II during infection and Crk was recruited to EBs at entry sites where it remained associated with nascent inclusions. Importantly, C. trachomatis mutants lacking TepP failed to recruit CrkI-II to inclusions, providing genetic confirmation of a direct role for this effector in the recruitment of a host factor. Finally, endocervical epithelial cells infected with a tepP mutant showed altered expression of a subset of genes associated with innate immune responses. We propose a model wherein TepP acts downstream of TARP to recruit scaffolding proteins at entry sites to initiate and amplify signaling cascades important for the regulation of innate immune responses to Chlamydia.Fil: Chen, Yi-Shan. University of Duke; Estados UnidosFil: Bastidas, Robert J.. University of Duke; Estados UnidosFil: Saka, Hector Alex. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. University of Duke; Estados UnidosFil: Carpenter, Victoria K.. Duke University Medical Center; . University of Duke; Estados UnidosFil: Richards, Kristian L.. Miami University; Estados UnidosFil: Plano, Gregory V.. Miami University; Estados UnidosFil: Valdivia, Raphael H.. University of Duke; Estados Unido