3,930 research outputs found
Protecting Society From Teenage Greed: A Proposal for Revising the Ages, Hours and Nature of Child Labor in America
The first section of this Article presents a picture of child labor throughout American history. It looks at child labor from the turn of the century to date. This section helps the reader understand the extent of changes in child labor over time. The second section presents a summary of federal and state child labor laws. This section shows that attempt to control employers who exploit children have changed only marginally. The third section of this Article explores social science data on the pros and cons of teenage employment.
This section focuses on the issue of teenage greed. First, the section explains what social scientists know and do not know about the consequences of teenage employment. Second, this section considers whether it is fair to label teenagers greedy. This section considers alternatives for reacting to child labor problems, such as educating parents, allowing teenagers to be free to choose their lifestyles, and seeking government protection for teenagers and society.
The Article concludes with a proposal for revising our child labor laws to react to the most prevalent kind of teenage employment today. Our proposal limits the number of hours most teenagers could work, but provides opportunities for more extensive employment in environments that are good for teens and society. It questions the uniquely American assumption that high school students should have serious commitments to the labor market. Our Article asserts that although the picture of the child laborer as a spoiled, self-centered teenager does not trigger the same emotions as the picture of the child laborer as a poor, overworked waif, the problem of teenage greed is much more pervasive today and needs a quick but thoughtful remedy
The effect of the COVID-19 pandemic on hip and knee arthroplasty patients in the United States: A multicenter update to the previous survey
Background: In March 2020, elective total hip and knee arthroplasty (THA and TKA) were suspended across the United States in response to the COVID-19 pandemic. We had previously published the results of a survey to the affected patients from 6 institutions. We now present the results of a larger distribution of this survey, through May and June 2020, to electively scheduled patients representing different regions of the United States.
Methods: Fifteen centers identified through the American Association of Hip and Knee Surgeons Research Committee participated in a survey study of THA and TKA patients. Patients scheduled for primary elective THA or TKA but canceled due to the COVID-19 elective surgery stoppage (3/2020-5/2020) were included in the study. Descriptive statistics along with subgroup analysis with Wilcoxon rank were performed.
Results: In total, surveys were distributed to 2135 patients and completed by 848 patients (40%) from 15 institutions. Most patients (728/848, 86%) had their surgery postponed or canceled by the surgeon or hospital. Unknown length of surgical delay remained the highest source of anxiety among survey participants. Male patients were more likely to be willing to proceed with surgery in spite of COVID-19. There were minimal regional differences in responses. Only 61 patients (7%) stated they will continue to delay surgery for fear of contracting COVID-19 while in the hospital.
Conclusion: Similar to the previous study, the most anxiety-provoking thought was the uncertainty, over if and when the canceled joint replacement surgery could be rescheduled. Patients suffering from the daily pain of hip and knee arthritis who have been scheduled for elective arthroplasty remain eager to have their operation as soon as elective surgery is allowed to resume
Calibrated Cylindrical Mach Probe In A Plasma Wind Tunnel
A simple cylindrical Mach probe is described along with an independent calibration procedure in a magnetized plasma wind tunnel. A particle orbit calculation corroborates our model. The probe operates in the weakly magnetized regime in which probe dimension and ion orbit are of the same scale. Analytical and simulation models are favorably compared with experimental calibration. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3559550
Concurrent sexual partnerships among individuals on HAART in South Africa: an opportunity for HIV prevention
Concurrent sexual partnerships, a common form of sexual partnering in much of southern Africa, play an important role in HIV transmission dynamics. This study examines the prevalence of concurrency and condom use among the general population and a sample of HAART patients in Cape Town, South Africa. The prevalence of reported concurrency was relatively high among a sample of HAART patients and in the general population (24% and 18% respectively) and reported consistent condom use was significantly higher among HAART patients compared to the general population (58% versus 20%);? perceived concurrency among the study populations' sexual partners was higher among HAART patients (35% versus 20%). Individuals on HAART report higher and more consistent use of condoms than the general population but the prevalence of concurrent relationships remains worryingly high. Greater programmatic attention should be given to promoting risk awareness of and behaviour change around concurrency both in the general population and amongst people living with HIV
Effects of Selected Wood Species and Moisture Content on PMDI Resin Application and Panel Properties
This study investigated the effect of selected species and moisture conditions on resin distribution and composite panel properties. Flakeboard composites were made from aspen, pine, or poplar flakes that were equilibrated to 4, 8, or 12% moisture content (MC). Resin droplet size (resin "footprint") was measured, as was the percentage of the flake surface that was covered by resin. Aspen flakes showed higher resin coverage and also larger resin droplet sizes. Conversely, pine and poplar flakes had smaller resin droplets and lower resin coverage per flake surface, suggesting greater pMDI penetration. Internal bond (IB) testing revealed optimal performance for aspen flakes at 12% precure MC, and poplar and pine flakes at 8% precure MC. Modulus of rupture and modulus of elasticity results correlated with IB results. Aspen panels bonded at 8 and 12% MC had minimal thickness swell
Effects of Isomer Ratio on Pmdi Resin Reactivity and Oriented Strandboard Properties
The effect of varying 2,4'-MDI to 4,4'-MDI isomer ratio in diphenylmethane diisocyanate (pMDI) adhesives was investigated. In addition to probing resin cure kinetics, oriented strandboard panels were produced to investigate the effect of isomer ratio on panel properties. With one exception, differential scanning calorimetry results showed a trend of increasing activation energy with increasing 4,4'-MDI content—the opposite of what was predicted. Results of internal bond testing indicate that increasing 4,4'-MDI content gave higher internal bond strength, but no correlation was evident between resin and panel density, MOR, MOE, or 24-h thickness swell. It is important to note that isomer ratio was not the only variable within the resin series; oligomer content and hence viscosity increased as 4,4'-MDI content increased, which complicated the analysis
Structural Classification of Metal Complexes with Three-Coordinate Centres
Attempts to describe the geometry about three-coordinate silver(I) complexes have proven difficult because interatomic angles generally vary wildly and there is no adequate or readily available classification system found in the literature. A search of the Cambridge Structural Database shows that complexes formed between any metal centre and three non-metal donors (18001 examples) usually adopt geometries that are quite different than ideal ‘textbook’ extremes of either trigonal planar (∼4% with α = β = γ = 120 ± 2°), T-shaped (∼0.05% with α = 180 ± 2°, β = γ = 90 ± 2°), or trigonal pyramidal (∼0.3% with α = β = γ = 110 ± 2°). Moreover, there are multiple variations of “Y-type” and “other” shapes that require elaboration. Thus, to assist in future structural descriptions, we developed a classification system that spans all known and yet-to-be-discovered three-coordinate geometries. A spreadsheet has also been constructed that utilizes the “shape-space” approach to extract the structural description from a user input of three angles about a tri-coordinate centre and the number of atoms in a plane. The structures of two silver(I) complexes of new N-donor ligands p-NH2C6H4C6H4CH(pz = pyrazol-1-yl)2, L1, and 2-ferrocenyl-4,5-di(2-pyridyl)imidazole, L2, illustrate the utility of this classification system
Expression of Ifnlr1 on intestinal epithelial cells is critical to the antiviral effects of IFN-lambda against norovirus and reovirus
Lambda interferon (IFN-λ) has potent antiviral effects against multiple enteric viral pathogens, including norovirus and rotavirus, in both preventing and curing infection. Because the intestine includes a diverse array of cell types, however, the cell(s) upon which IFN-λ acts to exert its antiviral effects is unclear. Here, we sought to identify IFN-λ-responsive cells by generation of mice with lineage-specific deletion of the receptor for IFN-λ, Ifnlr1. We found that expression of IFNLR1 on intestinal epithelial cells (IECs) in the small intestine and colon is required for enteric IFN-λ antiviral activity. IEC Ifnlr1 expression also determines the efficacy of IFN-λ in resolving persistent murine norovirus (MNoV) infection and regulates fecal shedding and viral titers in tissue. Thus, the expression of Ifnlr1 by IECs is necessary for the response to both endogenous and exogenous IFN-λ. We further demonstrate that IEC Ifnlr1 expression is required for the sterilizing innate immune effects of IFN-λ by extending these findings in Rag1-deficient mice. Finally, we assessed whether our findings pertained to multiple viral pathogens by infecting mice specifically lacking IEC Ifnlr1 expression with reovirus. These mice phenocopied Ifnlr1-null animals, exhibiting increased intestinal tissue titers and enhanced reovirus fecal shedding. Thus, IECs are the critical cell type responding to IFN-λ to control multiple enteric viruses. This is the first genetic evidence that supports an essential role for IECs in IFN-λ-mediated control of enteric viral infection, and these findings provide insight into the mechanism of IFN-λ-mediated antiviral activity. IMPORTANCE Human noroviruses (HNoVs) are the leading cause of epidemic gastroenteritis worldwide. Type III interferons (IFN-λ) control enteric viral infections in the gut and have been shown to cure mouse norovirus, a small-animal model for HNoVs. Using a genetic approach with conditional knockout mice, we identified IECs as the dominant IFN-λ-responsive cells in control of enteric virus infection in vivo. Upon murine norovirus or reovirus infection, Ifnlr1 depletion in IECs largely recapitulated the phenotype seen in Ifnlr1(−/−) mice of higher intestinal tissue viral titers and increased viral shedding in the stool. Moreover, IFN-λ-mediated sterilizing immunity against murine norovirus requires the capacity of IECs to respond to IFN-λ. These findings clarify the mechanism of action of this cytokine and emphasize the therapeutic potential of IFN-λ for treating mucosal viral infections
Host adapted serotypes of <i>Salmonella enterica</i>
Salmonella constitutes a genus of zoonotic bacteria of worldwide economic and health importance. The current view of salmonella taxonomy assigns the members of this genus to two species: S. enterica and S. bongori. S. enterica itself is divided into six subspecies, enterica, salamae, arizonae, diarizonae, indica, and houtenae, also known as subspecies I, II, IIIa, IIIb, IV, and VI, respectively. Members of Salmonella enterica subspecies enterica are mainly associated with warm-blooded vertebrates and are usually transmitted by ingestion of food or water contaminated by infected faeces. The pathogenicity of most of the distinct serotypes remains undefined, and even within the most common serotypes, many questions remain to be answered regarding the interactions between the organism and the infected host.
Salmonellosis manifests itself in three major forms: enteritis, septicaemia, and abortion, each of which may be present singly or in combination, depending on both the serotype and the host involved. Although currently over 2300 serovars of Salmonella are recognized, only about 50 serotypes are isolated in any significant numbers as human or animal pathogens and they all belong to subspecies enterica. Of these, most cause acute gastroenteritis characterized by a short incubation period and a severe systemic disease in man or animals, characterized by septicaemia, fever and/or abortion, and such serotypes are often associated with one or few host species.
It is the intention of this review to present a summary of current knowledge of these host-adapted serotypes of S. enterica. The taxonomic relationships between the serotypes will be discussed together with a comparison of the pathology and pathogenesis of the disease that they cause in their natural host(s). Since much of our knowledge on salmonellosis is based on the results of work on Typhimurium, this serotype will often be used as the baseline in discussion. It is hoped that an appreciation of the differences that exist in the way these serotypes interact with the host will lead to a greater understanding of the complex host–parasite relationship that characterizes salmonella infections
- …