6,470 research outputs found
The Deep Seabed Hard Mineral Resources Act: Legality and Necessity the U.S. Perspective
In June of 1980, the President of the United States signed into law the Deep Seabed Hard Mineral Resources Act, a piece of national legislation that will most definitely have international repercussions. The developing nations of the world are strongly opposed to unilateralism on the part of any nation, contending the minerals of the deep seabed belong to all nations and, therefore, the benefit from the exploitation of those minerals should likewise be shared by all nations. Why then, against such firm opposition from the less developed countries of the world, did the United States opt for unilateralism instead of waiting for an international agreement to regulate the resources of the deep seabed? This paper proposes to examine whether unilateral exploitation by the United States of the deep seabed beyond the limits of its national jurisdiction is authorized by existing international law, and secondly, is such legislation actually necessary? Are the vital interests of the United Stntes served by such legislation or will the international reaction be detrimental to U.S.interests abroad
Mercury advisories: Information, education, and fish consumption
This paper examines responses to a national FDA advisory that urged at-risk individuals to limit store-bought fish consumption due to the dangers of methyl-mercury. We investigate consumer response using both parametric and nonparametric methods. Some targeted consumers significantly reduced canned fish purchases as a result of the advisory, suggesting that information-based policies can achieve the issuing agencyâs goals. Education and newspaper readership were important determinants of response, suggesting that information acquisition and assimilation are key factors for risk avoidance. While some groups reduced consumption as a result of the advisory, we do not find a response among the relatively large group of at-risk households which met neither the education nor readership criteria. The advisory also had unintended spillover effects; some consumers not considered at-risk reduced consumption in response to the advisory.mercury; health information; health advisory; environmental health; fish consumption; childrenâs health; environmental risk; pollution;
What is the association between sickness absence, mortality and morbidity?
This paper examines the area-level relationships in England and Wales between sickness absence (âincapacity benefitâ), mortality and morbidity. It uses a random sample of incapacity benefit claims, and population counts of mortality and Census morbidity for local government districts. Although there is little correspondence between sickness absence claims by specific cause and mortality, all cause sickness absence has a strong relationship with all cause mortality (male r 0.74, p=0.00; female r 0.64, p=0.00) and it also has a very strong relationship with the Census measures of morbidity: LLTI (male r 0.98, p=0.00; female r 0.97, p=0.00) and ânot good healthâ (male r 0.99, p=0.00; female r 0.96, p=0.00). Incapacity benefit claims by all causes has the potential to provide an ongoing measure of area-level health in England and Wales
Designing Effective Questions for Classroom Response System Teaching
Classroom response systems (CRSs) can be potent tools for teaching physics.
Their efficacy, however, depends strongly on the quality of the questions used.
Creating effective questions is difficult, and differs from creating exam and
homework problems. Every CRS question should have an explicit pedagogic purpose
consisting of a content goal, a process goal, and a metacognitive goal.
Questions can be engineered to fulfil their purpose through four complementary
mechanisms: directing students' attention, stimulating specific cognitive
processes, communicating information to instructor and students via
CRS-tabulated answer counts, and facilitating the articulation and
confrontation of ideas. We identify several tactics that help in the design of
potent questions, and present four "makeovers" showing how these tactics can be
used to convert traditional physics questions into more powerful CRS questions.Comment: 11 pages, including 6 figures and 2 tables. Submitted (and mostly
approved) to the American Journal of Physics. Based on invited talk BL05 at
the 2005 Winter Meeting of the American Association of Physics Teachers
(Albuquerque, NM
Deficiency of RgpG causes major defects in cell division and biofilm formation, and deficiency of LytR-CpsAPsr family proteins leads to accumulation of cell wall antigens in culture medium by Streptococcus mutans
ABSTRACT
Streptococcus mutans
is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen.
S. mutans
strains deficient in
rgpG
, encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The
rgpG
deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the
rgpG
mutant existed primarily in chains of swollen, âsquarishâ dividing cells. Deficiency of
rgpG
also causes significant reduction in biofilm formation (
P
< 0.01). Double and triple mutants with deficiency in
brpA
and/or
psr
, genes coding for the LytR-CpsA-Psr family proteins BrpA and Psr, which were previously shown to play important roles in cell envelope biogenesis, were constructed using the
rgpG
mutant. There were no major differences in growth rates between the wild-type strain and the
rgpG brpA
and
rgpG psr
double mutants, but the growth rate of the
rgpG brpA psr
triple mutant was reduced drastically (
P
< 0.001). Under transmission electron microscopy, both double mutants resembled the
rgpG
mutant, while the triple mutant existed as giant cells with multiple asymmetric septa. When analyzed by immunoblotting, the
rgpG
mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the
brpA
and
psr
single mutants. These results suggest that RgpG in
S. mutans
plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope.
IMPORTANCE
Streptococcus mutans
, a major etiological agent of human dental caries, produces rhamnose-glucose polysaccharide (RGP) as the major cell wall antigen. This study provides direct evidence that deficiency of RgpG, the first enzyme of the RGP biosynthesis pathway, caused major defects in cell division and morphology and reduced biofilm formation by
S. mutans
, indicative of a significant role of RGP in cell division and biofilm formation in
S. mutans
. These results are novel not only in
S. mutans
, but also other streptococci that produce RGP. This study also shows that the LytR-CpsA-Psr family proteins BrpA and Psr in
S. mutans
are involved in attachment of RGP and probably other cell wall glycopolymers to the peptidoglycan. In addition, the results also suggest that BrpA and Psr may play a direct role in cell division and biofilm formation in
S. mutans
. This study reveals new potential targets to develop anticaries therapeutics.
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Evidence on the determinants and economic consequences of delegated monitoring
We investigate delegated monitoring by examining the determinants and effects of including cross-acceleration provisions in public debt contracts. We find that cross-acceleration provision use depends on borrowers' going concern relative to liquidation values, debt repayment structures, credit quality, and financial reporting quality. This suggests that the use of cross-acceleration provisions increases when the costs of cascading defaults are lower, the conflicts between creditor classes are higher, and the benefits of delegating monitoring to banks are higher. We also find a lower interest rate on public debt contracts with cross-acceleration provisions, but the rate reduction depends on borrowers' financial reporting quality
Spitzer Phase Curves of KELT-1b and the Signatures of Nightside Clouds in Thermal Phase Observations
We observed two full orbital phase curves of the transiting brown dwarf
KELT-1b, at 3.6um and 4.5um, using the Spitzer Space Telescope. Combined with
previous eclipse data from Beatty et al. (2014), we strongly detect KELT-1b's
phase variation as a single sinusoid in both bands, with amplitudes of
ppm at 3.6um and ppm at 4.5um, and confirm the secondary
eclipse depths measured by Beatty et al. (2014). We also measure noticeable
Eastward hotspot offsets of degrees at 3.6um and
degrees at 4.5um. Both the day-night temperature contrasts and the hotspot
offsets we measure are in line with the trends seen in hot Jupiters (e.g.,
Crossfield 2015), though we disagree with the recent suggestion of an offset
trend by Zhang et al. (2018). Using an ensemble analysis of Spitzer phase
curves, we argue that nightside clouds are playing a noticeable role in
modulating the thermal emission from these objects, based on: 1) the lack of a
clear trend in phase offsets with equilibrium temperature, 2) the sharp
day-night transitions required to have non-negative intensity maps, which also
resolves the inversion issues raised by Keating & Cowan (2017), 3) the fact
that all the nightsides of these objects appear to be at roughly the same
temperature of 1000K, while the dayside temperatures increase linearly with
equilibrium temperature, and 4) the trajectories of these objects on a Spitzer
color-magnitude diagram, which suggest colors only explainable via nightside
clouds.Comment: AJ in press. Updated to reflect the accepted versio
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CIO/CTO Job Roles: An Emerging Organizational Model
The position of Chief Information Systems Officer (CIO) has become a daunting job due to the myriad of business and technical responsibilities assigned to the organization\u27s top information systems (IS) executive. CIOs are being asked to successfully ensure the firm\u27s IS investments are continually aligned with its strategic business objectives, while also planning and maintaining an IT infrastructure that will meet the firm\u27s current and future information processing needs. Many CIOs are finding it extremely difficult to balance the two key roles of technician and businessperson successfully. Many business experts that have analyzed this problem have concluded that the tasks and responsibilities assigned to a typical CIO may be too overwhelming for a single person. This paper advances a formal organizational structure in which the typical responsibilities of the CIO position are re-allocated to two IS executives - the CIO and the Chief Technology Officer (CTO). This paper also describes which responsibilities should be retained by the CIO and which responsibilities should be delegated to the CTO. Finally, a discussion of the challenges and benefits associated with the implementation of CIO/CTO organizational leadership structure is presented
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