Beyond "The Average American Family": U.S. Cohort Parity Distributions and Fertility Concentration

In recent years IIASA's Population Program has made considerable strides in the analysis of heterogeneity in population dynamics. One area of particular application of this perspective has been in the analysis of fertility. Heterogeneity in fertility behavior gives rise to concentration, or dispersion, in the reproductive experiences of women of childbearing age, which in turn has numerous consequences and implications, as spelled out in this paper. King and Lutz focus on twentieth century U.S. women, and pay particular attention to the contrasts between the "baby boom" and "baby bust" cohorts. The authors' approach reveals some new insights into the intercohort comparisons

Passage and freshwater habitat requirements of anadromous lampreys: Considerations for conservation and control

Understanding the relationship between a species and its habitats is important for both conservation of imperiled species and control of invasive species. For migratory species, we hypothesize that maintaining connectivity between segregated habitats is more important than improving the quality of each habitat. In the case of anadromous lampreys of conservation concern, we posit that restoring passage routes between spawning, rearing and feeding habitats will result in higher larval abundance upstream from barriers than efforts to improve quality of these freshwater habitats. To explore this hypothesis, we reviewed conservation actions for native anadromous lampreys in freshwater and found that: i) improving passage between habitats results in immediate and quantifiable increases in larval abundance, ii) anadromous lampreys are capable of existing in suboptimal habitats, and iii) small reservoirs of production drive rapid expansion when anadromous lampreys are released from passage constraints. Hence, maintaining habitat connectivity is clearly crucial for conservation of anadromous lampreys. There are fewer examples of improvements to freshwater habitat that increased larval lamprey abundance, perhaps because lampreys are rarely the focus of these efforts. However, habitat limitations such as stream de-watering, chemical pollution, and scour occur and will likely be exacerbated by climate change. Documenting habitat actions that reverse these problems may provide evidence for the merits of lamprey-specific habitat improvement. Our observations are relevant to sea lamprey control in the Great Lakes because barriers and chemical treatment are key instruments of population regulation, and can be strategically deployed to limit production

Superhydrophobic structures on 316L stainless steel surfaces machined by nanosecond pulsed laser

In this paper nanosecond laser machining process was developed to improve the hydrophobicity of AISI 316L stainless steel surface. A geometrical model of laser machined Gaussian micro hole, together with constrain conditions, was established for the first time to predict surface contact angle and optimize structure geometries for maximizing its hydrophobicity. The effects of processing laser power and pitch of microstructures on the topography of the machined surface were investigated through laser machining experiment. Subsequently, the water droplet contact angle was measured to evaluate the hydrophobicity of different specimens. Results show that under the laser power of 10 W and 14 W, with the increase of the pitch of microstructures, the contact angle increases until it reaches its peak value then drops gradually. Under the large pitch of microstructure, the contact angle will increase with the increase of the processing laser power. Under the same pitch of microstructure, the contact angle will increase with the increase of ten-point height of surface topography, Sz which is a better parameter than Sa (arithmetical mean height) to characterise hydrophobicity of surface with Gaussian holes. This study shows that large Sz is an essential condition to form the stable and robust Cassie–Baxter state, i.e. a condition to achieve superhydrophobicity. The comparison between the predicted and measured contact angles in experiments shows that the proposed model can accurately predict contact angle and optimize the geometries of the microstructure to achieve maximum hydrophobicity

A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4

We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by the data, also leads to a natural description of the observed pattern of quark masses and mixings.Comment: 19 page

The latitudes, attitudes, and platitudes of watershed phosphorus management in North America

Phosphorus (P) plays a crucial role in agriculture as a primary fertilizer nutrient—and as a cause of the eutrophication of surface waters. Despite decades of efforts to keep P on agricultural fields and reduce losses to waterways, frequent algal blooms persist, triggering not only ecological disruption but also economic, social, and political consequences. We investigate historical and persistent factors affecting agricultural P mitigation in a transect of major watersheds across North America: Lake Winnipeg, Lake Erie, the Chesapeake Bay, and Lake Okeechobee/Everglades. These water bodies span 26 degrees of latitude, from the cold climate of central Canada to the subtropics of the southeastern United States. These water bodies and their associated watersheds have tracked trajectories of P mitigation that manifest remarkable similarities, and all have faced challenges in the application of science to agricultural management that continue to this day. An evolution of knowledge and experience in watershed P mitigation calls into question uniform solutions as well as efforts to transfer strategies from other arenas. As a result, there is a need to admit to shortcomings of past approaches, plotting a future for watershed P mitigation that accepts the sometimes two-sided nature of Hennig Brandt’s “Devil’s Element.

Evaluation of Irradiated Mandibles Using Emission Tomography, Bone Scans, and Radiography

This study compared radiographs, bone scans, and computed emission tomograms with histologic findings in irradiated mandibles of adult Rhesus monkeys. Although osteocytes were lost in the path of the beam, many vessels were partially or totally occluded, the periosteum degenerated, the marrow became fibrotic, and cancellous bone proliferated abundantly, no changes were noted with radiography, conventional bone scanning, or computed emission tomograms. These clinical methods of examination may misrepresent the true condition of irradiated bone because of inadequate sensitivity or balance among factors that control radioactive tracer uptake in bone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68112/2/10.1177_00220345800590120201.pd

APC/C-mediated multiple monoubiquitylation provides an alternative degradation signal for cyclin B1

The anaphase-promoting complex or cyclosome (APC/C) initiates mitotic exit by ubiquitylating cell-cycle regulators such as cyclin B1 and securin. Lys 48-linked ubiquitin chains represent the canonical signal targeting proteins for degradation by the proteasome, but they are not required for the degradation of cyclin B1. Lys 11-linked ubiquitin chains have been implicated in degradation of APC/C substrates, but the Lys 11-chain-forming E2 UBE2S is not essential for mitotic exit, raising questions about the nature of the ubiquitin signal that targets APC/C substrates for degradation. Here we demonstrate that multiple monoubiquitylation of cyclin B1, catalysed by UBCH10 or UBC4/5, is sufficient to target cyclin B1 for destruction by the proteasome. When the number of ubiquitylatable lysines in cyclin B1 is restricted, Lys 11-linked ubiquitin polymers elaborated by UBE2S become increasingly important. We therefore explain how a substrate that contains multiple ubiquitin acceptor sites confers flexibility in the requirement for particular E2 enzymes in modulating the rate of ubiquitin-dependent proteolysis

Parity-violating Electron Deuteron Scattering and the Proton's Neutral Weak Axial Vector Form Factor

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2= 0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51 +/- 0.57(stat) +/- 0.58(sys)ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let