2,208 research outputs found
Minimum time control of a nonlinear system
Time-optimal control problem studied for system representing second-order nonlinear differential equatio
Sterility as a ground for nullifying the marriage: Can Venter and Van Niekerk be reconciled?
From text: For a marriage to be valid, all the statutory and common law requirements must be satisfied. In a case where all the requirements of marriage are prima facie present, but one or more of the requirements is defective because of, relevant to this work, material misrepresentation, such marriage is regarded as voidable. With material misrepresentation, the question is whether a person in the position of the innocent party would not have entered into the marriage had s/he been aware of the true nature of things. Of course, not every aspect of misrepresentation can lead to material misrepresentation; the misrepresentation must relate to the material aspect of marriage, and those include serious diseases, impotence and others, but this paper deals only with sterility. Sterility has thus been defined as infertility, that is, “the ability to have sexual intercourse but unable to procreate children”
Fine-Structure FeII* Emission and Resonant MgII Emission in z = 1 Star-Forming Galaxies
We present a study of the prevalence, strength, and kinematics of ultraviolet
FeII and MgII emission lines in 212 star-forming galaxies at z = 1 selected
from the DEEP2 survey. We find FeII* emission in composite spectra assembled on
the basis of different galaxy properties, indicating that FeII* emission is
prevalent at z = 1. In these composites, FeII* emission is observed at roughly
the systemic velocity. At z = 1, we find that the strength of FeII* emission is
most strongly modulated by dust attenuation, and is additionally correlated
with redshift, star-formation rate, and [OII] equivalent width, such that
systems at higher redshifts with lower dust levels, lower star-formation rates,
and larger [OII] equivalent widths show stronger FeII* emission. We detect MgII
emission in at least 15% of the individual spectra and we find that objects
showing stronger MgII emission have higher specific star-formation rates,
smaller [OII] linewidths, larger [OII] equivalent widths, lower dust
attenuations, and lower stellar masses than the sample as a whole. MgII
emission strength exhibits the strongest correlation with specific
star-formation rate, although we find evidence that dust attenuation and
stellar mass also play roles in the regulation of MgII emission. Future
integral field unit observations of the spatial extent of FeII* and MgII
emission in galaxies with high specific star-formation rates, low dust
attenuations, and low stellar masses will be important for probing the
morphology of circumgalactic gas.Comment: 29 pages, 22 figures, 2 tables; accepted to Ap
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Matrix modification for enhancing the transport properties of the human cartilage endplate to improve disc nutrition.
Poor solute transport through the cartilage endplate (CEP) impairs disc nutrition and could be a key factor that limits the success of intradiscal biologic therapies. Here we demonstrate that treating the CEP with matrix metalloproteinase-8 (MMP-8) reduces the matrix constituents that impede solute uptake and thereby improves nutrient diffusion. Human CEP tissues harvested from four fresh cadaveric lumbar spines (age range: 38-66 years old) were treated with MMP-8. Treatment caused a dose-dependent reduction in sGAG, localized reductions to the amount of collagen, and alterations to collagen structure. These matrix modifications corresponded with 16-24% increases in the uptake of a small solute (376 Da). Interestingly, the effects of MMP-8 treatment depended on the extent of non-enzymatic glycation: treated CEPs with high concentrations of advanced glycation end products (AGEs) exhibited the lowest uptake compared to treated CEPs with low concentrations of AGEs. Moreover, AGE concentrations were donor-specific, and the donor tissues with the highest AGE concentrations appeared to have lower uptake than would be expected based on the initial amounts of collagen and sGAG. Finally, increasing solute uptake in the CEP improved cell viability inside diffusion chambers, which supports the nutritional relevance of enhancing the transport properties of the CEP. Taken together, our results provide new insights and in vitro proof-of-concept for a treatment approach that could improve disc nutrition for biologic therapy: specifically, matrix reduction by MMP-8 can enhance solute uptake and nutrient diffusion through the CEP, and AGE concentration appears to be an important, patient-specific factor that influences the efficacy of this approach
The Specific Globular Cluster Frequencies of Dwarf Elliptical Galaxies from the Hubble Space Telescope
The specific globular cluster frequencies (S_N) for 24 dwarf elliptical (dE)
galaxies in the Virgo and Fornax Clusters and the Leo Group imaged with the
Hubble Space Telescope are presented. Combining all available data, we find
that for nucleated dEs --- which are spatially distributed like giant
ellipticals in galaxy clusters --- S_N(dE,N)=6.5 +- 1.2 and S_N increases with
M_V, while for non-nucleated dEs --- which are distributed like late-type
galaxies --- S_N(dE,noN)=3.1 +- 0.5 and there is little or no trend with M_V.
The S_N values for dE galaxies are thus on average significantly higher than
those for late-type galaxies, which have S_N < 1. This suggests that dE
galaxies are more akin to giant Es than to late-type galaxies. If there are
dormant or stripped irregulars hiding among the dE population, they are likely
to be among the non-nucleated dEs. Furthermore, the similarities in the
properties of the globular clusters and in the spatial distributions of dE,Ns
and giant Es suggest that neither galaxy mass or galaxy metallicity is
responsible for high values of S_N. Instead, most metal-poor GCs may have
formed in dwarf-sized fragments that merged into larger galaxies.Comment: 12 pages (uses aaspp4.sty), 2 figures, 1 table, to appear in the
Astrophysical Journa
The Star-Forming Dwarf Galaxy Populations of two z ~ 0.4 Clusters: MS1512.4+3647 and Abell 851
We present the results of a deep narrow-band [OII] 3727 \AA emission-line
search for faint ( 27), star-forming galaxies in the field of the
MS1512.4+3647 cluster. We find no evidence for an over-density of emission-line
sources relative to the field at 0.4 (Hogg et al. 1998), and therefore
conclude that the MS1512.4+3647 sample is dominated by field [OII]
emission-line galaxies which lie along the 180 Mpc line of sight
immediately in front and behind the cluster. This is surprising, given that the
previously surveyed cluster Abell 851 has 3-4 times the field
emission-line galaxy density (Martin et al. 2000). We find that the
MS1512.4+3647 sample is deficient in galaxies with intermediate colors (1.0 2.0) and implied star-formation exponential decay timescales
100 Myr - 1 Gyr that dominate the Abell 851 emission-line galaxy population.
Instead, the majority of [OII] emission-line galaxies surrounding the
MS1512.4+3647 cluster are blue () and forming stars in bursts
with 100 Myr. In both samples, galaxies with the shortest
star-formation timescales are preferentially among the faintest star-forming
objects. Their i luminosities are consistent with young stellar populations
\sim 10^8 - 10^9 \Msun, although an additional factor of ten in stellar mass
could be hiding in underlying old stellar populations. We discuss the
implications for the star-formation histories of dwarf galaxies in the field
and rich clusters.Comment: 26 pages, including 5 tables and 13 figures; accepted for publication
in the Astrophysical Journa
Rationeel onkruidbeheer op verhardingen
Verslag van een workshop over duurzaam onkruidbeheer op verhardingen. Belangrijkste thema's waren afspoeling van herbiciden en kosten-effectief onkruidbehee
Inventory of observed unexpected environmental effects of genetically modified crops
In general, it can be concluded that very few clearly unexpected effects were observed during the large scale post-release growing of herbicide-tolerant crops and Bt crops. Of course, one has to keep in mind Applied Plant Research (Praktijkonderzoek Plant & Omgeving ) 14 that there will always be an element of subjectivity in assessing effects as “unexpected”. Furthermore, it is also possible that certain effects are becoming visible only after a longer period than 10 – 15 years, but no indications for such effects were found in the literature. Besides the reports about the Farm Scale Evaluations no other reports were found with information about effects of GM crops on biodiversity in ecosysystems surrounding the production fields. Unexpected effects caused directly by the genetic modification were not found. Only in herbicide-tolerant crops, we concluded to some indirect unexpected effects: the reduced uptake of micro-nutrients and some positive and negative effects on susceptibility to diseases. These effects were specific to herbicide use with glyphosate-tolerant crops. Based on this, it was not possible to draw general conclusions for developing protocols for post-release monitoring of environmental effect
Decision Processes about Condom Use among Shelter-Homeless LGBT Youth in Manhattan
Health behavior interventions based on Theory of Planned Behavior address participants' personally-held beliefs, perceived social norms, and control over the behavior. New data are always needed to “member check” participants' decision processes and inform interventions. This qualitative study investigates decision processes around condom use among 81 homeless LGBT youth ages 18–26. Findings indicated considerable endorsement of the conventional policy of always using condoms, promulgated in HIV prevention education targeting this population. Although some participants reported risk behavior in contexts of sex work, survival sex, casual encounters, open relationships, and substance use, most were aware of these risks and consistently safe in those situations. Condoms use boundaries became vulnerable in states of emotional need and negative mood. The only effect participants acknowledged of homelessness on condom use was indirect, through negative mood states. The most prevalent context of condom non-use was with long-term primary partners, a potential area of vulnerability because, of 13 participants for HIV or HCV, nine mentioned how they had been infected, and all nine believed they had acquired it from a primary partner. Findings imply programs should emphasize HIV risk potential within long-term romantic partnerships and mental health services to remediate negative mood states
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