Demographic Change and the Structure of Wages: A Demand-Theoretic Analysis for Brazil

With rapidly declining fertility and increased longevity the age structure of the labor force in developing countries has changed rapidly. Changing relative supply of workers by age group, and by educational attainment, can have profound effects on labor costs. Their impacts on earnings have been heavily studied in the United States but have received little attention in Asia and Latin America, where supply shocks are at least as large and have often proceeded less evenly across the economy. We use data on 502 local Brazilian labor markets from Censuses 1970-2000 to examine the extent of substitution among demographic groups as relative supply has changed. The results suggest that age-education groups are imperfect substitutes, so that larger age-education cohorts see depressed wage rates, particularly among more-educated groups. The extent of substitution has increased over time, so that the decreasing size of the least-skilled labor force today is barely raising its remaining members' wages.

Periostin increases migration and proliferation of human periodontal ligament fibroblasts challenged by tumor necrosis factor ‐α and Porphyromonas gingivalis lipopolysaccharides

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106894/1/jre12120.pd

Preliminary insight into the periostin leverage during periodontal tissue healing

BackgroundTissue repair and regeneration is assisted by the efficient coordination of cell and extracellular matrix interactions mediated by matricellular molecules such as periostin. Given its high expression around the teeth, the periodontal organ represents an ideal system to capture the protein dynamics during wound healing.MethodsAn observational prospective case–control study was designed to characterize periostin changes over time after periodontal surgery in tissue, oral fluids and serum by histological, protein and mRNA analyses.ResultsHistological analysis showed lower periostin with a diffuse local distribution pattern in disease patients. Levels of periostin in gingival crevicular fluid (GCF) increased over time for both groups, more noticeably in the periodontitis subjects. A transient and subtle change in circulating periostin levels was also noticed. The mRNA periostin levels contrasted with the protein levels and may indicate the underlying post‐transcriptional regulatory process during chronic inflammation. Levels of known periodontal disease biomarkers such as IL‐β, IL1‐α, TNF‐α, MIP‐1α and CRP served as tissue stability markers and complemented the clinical parameters recorded.ConclusionThe transient local increase in GCF periostin after eliminating the local etiology in periodontally affected sites suggests its importance in the maturation and stability of the connective tissue. The decreasing levels observed as the tissue healed highlight its spatial/temporal significance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113755/1/jcpe12432.pd

Anticooperativity in diffusion-controlled reactions with pairs of anisotropic domains: a model for the antigen-antibody encounter

The encounter between anisotropic agents in diffusion-controlled reactions is a topic of very general relevance in chemistry and biology. Here we introduce a simplified model of encounter of an isotropic molecule with a pair of partially reacting agents and apply it to the encounter reaction between an antibody and its antigen. We reduce the problem to the solution of dual series relations, which can be solved iteratively, yielding the exact solution for the encounter rate constant at any desired order of accuracy. We quantify the encounter effectiveness by means of a simple indicator and show that the two binding centers systematically behave in an anticooperative fashion. However, we demonstrate that a reduction of the binding active sites allows the composite molecule to recover binding effectiveness, in spite of the overall reduction of the rate constant. In addition, we provide a simple formula that enables one to calculate the anticooperativity as a function of the size of the binding site for any values of the separation between the two active lobes and of the antigen size. Finally, some biological implications of our results are discusse

Solar-Sail Navigation: Estimation of Force, Moments, and Optical Parameters

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77367/1/AIAA-24340-772.pd

Screening and Breeding for Bermudagrass Stem Maggot (BSM) Resistance Using U.S. Bermudagrass Germplasm

Bermudagrass (Cynodon sp.) is an important perennial forage grass grown in many parts of the world. Bermudagrass Stem Maggot (BSM) (Atherigona reversura Villeneuve) is an insect pest that reduces forage yield and nutritive value if it is not controlled. The pest, native to SE Asia, was first documented in North America in 2009 and is now considered invasive. A collection of over 300 forage bermudagrass accessions was evaluated in the field for susceptibility to BSM in 2014 and 2015. Tolerant lines and susceptible checks were then evaluated for yield loss due to BSM in a replicated field study by comparing insecticide-sprayed plots to unsprayed plots in Tifton, GA starting in 2016 continuing through the summer of 2019. For mid to late summer harvests during 2017, BSM reduced yield of Alicia and Russell by over 40% and Tifton 85 by up to 35%. However, tolerant accessions exhibited less than 10% yield loss and had dry matter yields comparable to Tifton 85. Nutritive value will also be assessed. These accessions will be further evaluated and used in plant breeding

Genetic Improvement of Bermudagrass for Hay Producers

Bermudagrass (Cynodon spp.) is considered the most valuable warm-season perennial grass for hay producers in the Southeastern United States. Bermudagrass genotypes have overall good forage quality, high yields, and store well. However, there are challenges to producing good hay for the market. First, early green-up in the spring is needed to allow for four to five productive clippings during the summer. When first establishing production fields, quick emergence and cover are important for reducing weeds. Forage bermudagrass is somewhat tolerant to drought, however, low rainfall substantially reduces yields. If rainfall is too abundant, it is difficult to have timely curing in the field for baling. This is especially true for the higher quality thick-stemmed cultivars such as Tifton 85. More recently, the bermudagrass stem maggot (BSM, Atherigona reversura) has caused yield reductions and reduced net income for hay producers. Plant breeding has attempted to address all these issues. This talk will highlight some areas of research that has been done over the past few decades to improve bermudagrass for hay production

Moving Warm-Season Forage Bermudagrass (\u3ci\u3eCynodon\u3c/i\u3e sp.) into Temperate Regions of North America

Warm-season (C4) perennial grasses are grown over millions of hectares in the Southeastern United States. These grasses produce optimal growth at 30 to 38°C diurnal temperature. Bermudagrass (Cynodon sp.) has been adopted as the preferred forage for many livestock and hay producers. Compared to other native and introduced warm-season perennial grass species, improved bermudagrass varieties produce high biomass with enhanced digestibility for ruminant grazing or feed. Until the 1930’s pastures in the region consisted of unimproved ‘common’ bermudagrass (Cynodon dactylon (L.) Pers.) that had been introduced earlier. However, in the early 20th century, new germplasm, including stargrass (C nlemfuënsis Vanderyst) was collected, primarily from Africa. This germplasm provided a source for major improvements in yield and digestibility. Unfortunately, stargrass is not cold tolerant, limiting it to regions between 30°N and 30°S. Intercrossing of C. nlemfuënsis with C. dactylon has produced highly successful cultivars, such as Tifton 85, which can survive at northern latitudes of at least 35°. However, there has been a desire to extend adaptation further north into the warm-season/cool-season grass transition zone. This would require a combination of breeding to improve cold tolerance in clonally-propagated varieties and development of seeded varieties that could be re-seeded following extremely cold winters. Earlier work at Oklahoma State University indicated that some cultivars had significantly different tolerance to freeze. Screening the Tifton, GA, USA core collection of 175 accessions in a northern, high-altitude location, has identified germplasm with promising cold tolerance. A breeding line (Tifton 79-16) had significantly higher yields at the northern Georgia location than the cold tolerant cultivar (Tifton 44). A number of plant introductions had higher yields as well

A comparative study of top-down and bottom-up carbon nanodots and their interaction with mercury ions

We report a study of carbon dots produced via bottom-up and top-down routes, carried out through a multi-technique approach based on steady-state fluorescence and absorption, time-resolved fluorescence spectroscopy, Raman spectroscopy, infrared spectroscopy, and atomic force microscopy. Our study focuses on a side-to-side comparison of the fundamental structural and optical properties of the two families of fluorescent nanoparticles, and on their interaction pathways with mercury ions, which we use as a probe of surface emissive chromophores. Comparison between the two families of carbon dots, and between carbon dots subjected to different functionalization procedures, readily identifies a few key structural and optical properties apparently common to all types of carbon dots, but also highlights some critical differences in the optical response and in the microscopic mechanism responsible of the fluorescence. The results also provide suggestions on the most likely interaction sites of mercury ions at the surface of carbon dots and reveal details on mercury-induced fluorescence quenching that can be practically exploited to optimize sensing applications of carbon dots

Solvent-induced micelle formation in a hydrophobic interaction model

We investigate the aggregation of amphiphilic molecules by adapting the two-state Muller-Lee-Graziano model for water, in which a solvent-induced hydrophobic interaction is included implicitly. We study the formation of various types of micelle as a function of the distribution of hydrophobic regions at the molecular surface. Successive substitution of non-polar surfaces by polar ones demonstrates the influence of hydrophobicity on the upper and lower critical solution temperatures. Aggregates of lipid molecules, described by a refinement of the model in which a hydrophobic tail of variable length interacts with different numbers of water molecules, are stabilized as the length of the tail increases. We demonstrate that the essential features of micelle formation are primarily solvent-induced, and are explained within a model which focuses only on the alteration of water structure in the vicinity of the hydrophobic surface regions of amphiphiles in solution.Comment: 11 pages, 10 figures; some rearrangement of introduction and discussion sections, streamlining of formalism and general compression; to appear in Phys. Rev.