Productivy Growth and Tenure: A Test of on-the-Job Training Theories of Wage and Productivy Growth

[Excerpt] Studies have found consistently that there is a strong positive correlation between a worker\u27s tenure with a firm and that individual\u27s wage rate. Becker\u27s (1975) on-the-job training (OJT) model is the most widely accepted explanation for this association. The OJT model posits that new employees receive training early in their tenure, which raises their productivity both in and outside the firm. Competition forces the employer to pay employees who have completed this training at least as much as they are worth outside the firm less transfer costs. Jobs that offer such training are more attractive than jobs that do not, so competition forces down the entry wage of jobs that provide training below the entry wage of jobs that offer no training. During the training period, the supervisors and other workers are spending time away from other activities, helping the new employee learn the job. The new employee may also spend time in learning activities instead of production activities. In order to offer training, the employer must be compensated for the resulting sacrifice in current output. When the training provides general skills, the only way such compensation can be provided is by a further lowering of the entry wage. Thus, there are two forces that cause wage rates of new employees to rise: the increase of the employee\u27s productivity and the decline of training expenses. When training is entirely specific, and therefore does not raise the worker\u27s productivity in other firms, the forces causing a rising wage profile are weaker. They do not disappear, however, for a rising wage profile reduces the quit rate of trained workers, and thus protects the firm\u27s investment in training

Navigating the Middle Grades and Preparing Students for High School Graduation

This brief presents preliminary findings from an exploratory study of New York City students' transitions into, through, and out of the middle grades. Our analysis reveals that students' attendance and achievement in their early schooling (fourth grade) predict whether students are likely to graduate from high school many years later. Further, we find that many students begin the middle grades on-track to graduate high school but fall off this trajectory before the end of eighth grade. These findings suggest that teachers and administrators should pay close attention to students whose attendance and math achievement fall during the middle grades, as these students are particularly at risk for not graduating from high school on time

Inclusion of non-spherical components of the Pauli blocking operator in (p,p') reactions

We present the first calculations of proton elastic and inelastic scattering in which the Pauli blocking operator contains the leading non-spherical components as well as the usual spherical (angle-averaged) part. We develop a formalism for including the contributions to the effective nucleon-nucleon interaction from the resulting new G-matrix elements that extend the usual two-nucleon spin structure and may not conserve angular momentum. We explore the consequences of parity conservation, time reversal invariance, and nucleon-nucleon antisymmetrization for the new effective interaction. Changes to the calculated cross section and spin observables are small in the energy range from 100 to 200 MeV.Comment: 24 pages, 4 figures, to be published in Physical Review

Extended Bose-Hubbard model with incompressible states at fractional numbers

The Bose-Hubbard model is extended to include nearest and far neighbor interactions and is related to the fractional quantum Hall effect (FQHE). Both models may be studied in optical lattices with quantum gases. The ground state is calculated for the extended Bose-Hubbard model with strong repulsive interactions (weak hopping). Incompressible Mott insulator states are found at rational filling fractions compatible with the principal and secondary FQHE filling fractions of the lowest Landau levels observed experimentally. It is discussed to which extent these states at fractional filling survive or undergoes a Mott insulator transition to a superfluid as hopping terms are included.Comment: Revised version, to appear in PR

Exploring the use of nature as an adjunct to psychological interventions for depression in young populations

Depression in adolescence is a global priority and it is critical to identify effective and accessible interventions. This systematic review aimed to synthesise experimental research on nature-based interventions (NBIs), to determine effects on depressive symptoms in young people. The secondary research question sought to understand characteristics of effective NBIs. A comprehensive systematic search was conducted across major and grey literature databases and papers were screened according to specified criteria. Participants’ ages were required to be between 10 and 24 years and studies needed to use an experimental design, including a control group. Experimental conditions were defined by psychotherapeutic interventions with nature exposure and outcomes measured either clinical symptomatology or subjective states of depression. Ten papers were identified, quality assessed and summarised in a narrative synthesis. Thirteen significant effects were reported in nine studies, highlighting the potential for NBIs as effective interventions for depressive symptoms in young people. However, due to methodological biases, such as lack of randomisation or control over group differences and frequent use of passive control groups, there remains considerable uncertainty over the effectiveness of NBIs. Characteristics of effective NBIs are tentatively discussed, however, further work is needed to clarify which aspects specifically contribute to the beneficial effects observed. Future research should seek to address the limitations of small samples, selection biases and test NBIs against more comparable and evidence-based interventions. It is hoped future studies will consider the inclusion of clinical populations, to explore the utility of NBIs as a treatment option for adolescent depression

Five unconventional fuels: geology and environment

Unconventional fuels may present a viable partial replacement for conventional fossil fuel reservoirs (such as sandstone and limestone) in rocks onshore and offshore. These alternative fuels are obtained from distinct sources and employ extraction technologies which are very different to those used to extract conventional hydrocarbons. Oil sands (also known as tar sands or bituminous sands) are loose sand or partially consolidated sandstone containing viscous bitumen. Resources occur in Canada, Kazakhstan and Russia and estimated worldwide deposits represent 2500 billion barrels of oil in place. Oil sands have only recently been considered to be part of the world's oil reserves, as higher oil prices and new technology enable profitable extraction and processing. Converting oil sands to liquid fuels requires energy for steam injection and refining. Methane from coal includes gas recovered from active (coal mine methane or CMM) and abandoned mines (abandoned mine methane or AMM), as well as methane recovered from undisturbed or ‘virgin’ coal seams (usually known as coal bed methane or CBM). Gas from these sources is already produced on a modest scale and exploration is ongoing for further prospects. Gas can also be derived from coal by combustion of underground coal seams in situ to produce synthetic gas (‘syngas’). This process is usually known as 'underground coal gasification' (UCG). This technology is also in its infancy both in terms of engineering the subsurface process and in the understanding of subsurface and surface environmental impacts. Methane hydrates (methane gas trapped in ‘cages’ of water molecules, resembling ice) have been recovered from, or are postulated for, virtually all marine shallow sediment continental margins around the world and a few areas onshore. Volumes of about 2 x 1014m3 methane in‐place have been estimated for this potential resource. To quantify reserve potential and to identify suitable methods of methane extraction, a full understanding of how hydrates are held within sediments is required. A less well known unconventional fuel is subsurface hydrogen. Small flows of hydrogen naturally occur in some mines and in deep oceans associated with abiogenic and biogenic methane, nitrogen and helium. The main geological environment that is promising for exploration is the tectonic remnants of ancient ocean floor known as ophiolites. The main accessible onshore areas are where ophiolites are found tectonically emplaced within fold belts. Though unconventional fuels represent an enormous resource overall, some of the technology is immature and many of the environmental impacts of their exploitation are unknown. Apart from subsurface hydrogen, all are hydrocarbons and thus are constrained in their use in countries which may limit carbon emissions either now or in the future

Bisaccate pollen from the Early Permian OSPZ3a Sub-Biozone of the Lower Gharif Member, Oman

The OSPZ3a Sub-Biozone, associated with the lowest part of the Lower Gharif Member, is part of biozonal scheme that was intended to unify the palynological schemes across Arabia. This paper describes and illustrates the main bisaccate pollen taxa from the OSPZ3a Sub-Biozone of the Well A cored well, Oman, between 2842.69 and 2852.82 m, where they are unusually well preserved. Pteruchipollenites indarraensis which is the most common bisaccate pollen taxon, reaching 40 to 50% of assemblages, is here placed in synonymy with Alisporites tenuicorpus Balme, 1970, the latter being its junior synonym. Striatopodocarpites cancellatus consistently first occurs in the OSPZ3a Sub-Biozone, and well-preserved specimens are present in Well A, but Arabian specimens appear to have a wider range of morphology, mainly in the arrangement of taeniae, than the type material. The relationship of the genus Striatopodocarpites to Verticipollenites Bharadwaj, 1962, Lahirites Bharadwaj, 1962 and Hindipollenites Bharadwaj, 1962 is also examined with the result that Striatopodocarpites is asserted as the senior synonym. The taeniate bisaccate pollen Hamiapollenites fusiformis Marques-Toigo, 1974 is unusually common in the Well A assemblages and its morphology is found to be distinct from the similar multi-taeniate bisaccate taxon Striatoabieites multistriatus (Balme and Hennelly) Hart, 1964, with which it is sometimes placed in synonymy

Permian palynostratigraphy: a global overview

Permian palynostratigraphic schemes are used primarily to correlate coal- and hydrocarbon-bearing rocks within basins and between basins, sometimes at high levels of biostratigraphic resolution. Up to now, their main shortcoming has been the lack of correlation with schemes outside the basins, coalfields and hydrocarbon fields that they serve, and chiefly a lack of correlation with the international Permian scale. This is partly because of phytogeographical provinciality from the Guadalupian onwards, making correlation between regional palynostratigraphic schemes difficult. However, local high-resolution palynostratigraphic schemes for regions are now being linked either by assemblage-level quantitative taxonomic comparison or by the use of single well-characterized palynological taxa that occur across Permian phytogeographical provinces. Such taxa include: Scutasporites spp., Vittatina spp., Weylandites spp., Lueckisporites virkkiae, Otynisporites eotriassicus and Converrucosisporites confluens. These palynological correlations are being facilitated and supplemented with radiometric, magnetostratigraphic, independent faunal and strontium isotopic dating