Performance evaluation of the New Connecticut Leading Employment Index using lead profiles and BVAR models

The leading and coincident employment indexes for the state of Connecticut developed following the recession of the early 1990s fell short of expectations. This paper performs two tasks. First, it describes the process of revising the Connecticut Coincident and Leading Employment Indexes. Second, it analyzes the statistical properties and performance of the new indexes by comparing the lead profiles of the new and old indexes as well as their out‐of‐sample forecasting performance, using the Bayesian Vector Autoregressive (BVAR) method. The new coincident index shows improved performance in dating employment cycle chronologies. The lead profile test demonstrates that superiority in a rigorous, non‐parametric statistic fashion. The mixed evidence on the BVAR forecasting experiments illustrates that leading indexes properly predict cycle turning points and do not necessarily provide accurate forecasts except at turning points, a view that our results support. Copyright © 2006 John Wiley & Sons, Ltd.     

Snapshots of cooperative atomic motions in the optical suppression of charge density waves

Macroscopic quantum phenomena such as high-temperature superconductivity, colossal magnetoresistance, ferrimagnetism and ferromagnetism arise from a delicate balance of different interactions among electrons, phonons and spins on the nanoscale. The study of the interplay among these various degrees of freedom in strongly coupled electron-lattice systems is thus crucial to their understanding and for optimizing their properties. Charge-density-wave (CDW) materials, with their inherent modulation of the electron density and associated periodic lattice distortion, represent ideal model systems for the study of such highly cooperative phenomena. With femtosecond time-resolved techniques, it is possible to observe these interactions directly by abruptly perturbing the electronic distribution while keeping track of energy relaxation pathways and coupling strengths among the different subsystems. Numerous time-resolved experiments have been performed on CDWs, probing the dynamics of the electronic subsystem. However, the dynamics of the periodic lattice distortion have been only indirectly inferred. Here we provide direct atomic-level information on the structural dynamics by using femtosecond electron diffraction to study the quasi two-dimensional CDW system 1T-TaS(2). Effectively, we have directly observed the atomic motions that result from the optically induced change in the electronic spatial distribution. The periodic lattice distortion, which has an amplitude of ～0.1??, is suppressed by about 20% on a timescale (～250 femtoseconds) comparable to half the period of the corresponding collective mode. These highly cooperative, electronically driven atomic motions are accompanied by a rapid electron-phonon energy transfer (～350 femtoseconds) and are followed by fast recovery of the CDW (～4 picoseconds). The degree of cooperativity in the observed structural dynamics is remarkable and illustrates the importance of obtaining atomic-level perspectives of the processes directing the physics of strongly correlated systems.     

4-Dedimethylamino-4-epiamino-5a,6-anhydrotetracycline

Zusammenfassung Die Isolierung sowie die chemischen, biologischen und physikalischen Eigenschaften von 4-Dedimethylamino-4-epiamino-5a,6-anhydrotetracyclin werden beschrieben. Die Beziehungen zu anderen Anhydrotetracyclinen werden diskutiert.     

Complementarity between sperm surface beta-1,4-galactosyltransferase and egg-coat ZP3 mediates sperm-egg binding.

Despite its importance, the molecular basis of mammalian gamete recognition has remained unclear. The enzyme beta-1,4-galactosyltransferase (Gal-transferase) has been viewed traditionally as a biosynthetic component of the Golgi complex, but is also found on the surface of many cells where it can bind its specific glycoside substrate on adjacent cell surfaces or in the extracellular matrix. In mouse it has been suggested that Gal-transferase on the sperm head mediates fertilization by binding oligosaccharide residues in the egg coat, or zona pellucida, and that the ability of the zona pellucida to bind sperm is conferred by oligosaccharides of the ZP3 glycoprotein. However, it has not been confirmed that Gal-transferase and ZP3 are in fact complementary gamete receptors whose interaction mediates sperm-egg binding. Here we show that mouse sperm Gal-transferase specifically recognizes those oligosaccharides on ZP3 that have sperm-binding activity, but does not interact with other zona pellucida glycoproteins. In contrast, all zona pellucida glycoproteins are recognized by non-sperm Gal-transferase, demonstrating a more stringent substrate specificity for the sperm enzyme. This interaction is required for sperm-egg binding because blocking or removing the binding site for Gal-transferase on ZP3 inhibits its ability to bind sperm. After the release of the sperm acrosome, the transferase relocalizes to a new membrane domain where it can no longer bind to ZP3, which is consistent with the inability of acrosome-reacted sperm to bind ZP3 or to initiate binding to the zona pellucida. Following fertilization, ZP3 is modified by egg cortical granule secretions so that it loses sperm receptor activity, which can be accounted for by a selective loss of its binding site for sperm Gal-transferase. These results show that sperm surface beta-1,4-galactosyltransferase and the egg-coat glycoprotein ZP3 are complementary adhesion molecules that mediate primary gamete binding in the mouse.