Marine alien species of South Africa - status and impacts Robinson, T.B; Griffiths, C.L. (Cape Town Univ., Rondebosch (South Africa). Zoology Dept.); McQuaid, C.D ...
African journal of marine science,
2005, Letnik:
27, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The current status of marine alien species along the South African coast is reviewed and the ecological and economic impacts of these invasions are discussed. In all, 10 confirmed extant alien and 22 ...cryptogenic species are recorded from the region. All 10 alien species support well-established populations and the majority of these remain restricted in distribution to sheltered bays, estuaries and harbours. Only one species, the Mediterranean mussel Mytilus galloprovincialis, has spread extensively along the coast and caused significant ecological impacts. These include the competitive displacement of indigenous species and a dramatic increase in intertidal mussel biomass. These changes have also increased available habitat for many infaunal species and resulted in enhanced food supply for intertidal predators. Considerable economic benefits have also resulted from this invasion because M. galloprovincialis forms the basis of the South African mussel culture industry.
Status construction theory argues that interaction between people with unequal structural advantages is crucial in the development and spread of status value beliefs about people's distinguishing ...attributes. A central claim is that goal-oriented encounters between those who differ in material resources as well as in an easily observed nominal attribute create status beliefs about that attribute which favor the "richer" actors' attribute category. We conduct an experimental test using dyadic, same-sex encounters between participants who differ in pay level and a "mere difference" attribute; the claim is supported for males and females. Status beliefs are distinguished from own-group favoritism by their acceptance by those they disadvantage. A second experiment and other evidence suggest that the interactional hierarchy associated with pay and the distinguishing attribute in such doubly dissimilar encounters pressures low-pay subjects to accept beliefs that disadvantage them. This acceptance is key to the power of interaction to transform structural advantages into status beliefs.
Diabet. Med. 29, 609–613 (2012)
Aims This study investigated dynamic cerebral autoregulation in Type 2 diabetes, where dynamic cerebral autoregulation may be impaired as a consequence of ...microvascular changes and/or autonomic neuropathy.
Methods Eleven healthy control subjects and 11 age‐ and sex‐matched patients with Type 2 diabetes controlled with lifestyle modifications or oral anti‐diabetes treatment were recruited. Dynamic cerebral autoregulation was calculated by the autoregressive moving average autoregulatory index from a continuous blood pressure and R‐R interval (time between each ventricular systole) recording. End‐tidal carbon dioxide was also monitored and changes in response to breath holding and hyperventilation as a metabolic stimulus were measured.
Results No significant differences were seen in cerebral blood flow velocity at baseline, or in response to breath holding between people with diabetes and control subjects, although the cerebral blood flow velocity response associated with hyperventilation was significantly reduced in the diabetes group. No significant differences in dynamic cerebral autoregulation were seen at baseline or in response to respiratory manoeuvres between the groups.
Conclusions Dynamic cerebral autoregulation is not impaired in patients with Type 2 diabetes, although a small difference could not be excluded as the study was only powered to detect an autoregulatory index difference > 2 units. Further study in a larger population with a spectrum of disease severity may reveal clinically important differences.
The African pygmy mice (genus Mus, subgenus Nannomys) are recognized for their highly conserved morphology but extensive chromosomal diversity, particularly involving sex-autosome translocations, one ...of the rarest chromosomal rearrangements among mammals. It has been shown that in the absence of unambiguous diagnostic morphological traits, sex-autosome translocations offer accurate taxonomic markers. For example, in Mus minutoides, irrespective of the diploid number (which ranges from 2n = 18 to 34), all specimens possess the sex-autosome translocations (X.1) and (Y.1) that are unique to this species. In this study, we describe a new cytotype that challenges this view. Males are characterized by the translocation (Y.1) only, while females carry no sex-autosome translocation, the X chromosome being acrocentric. Hence, although sex-autosome translocations (X.1) and (Y.1) are still diagnostic when one or both are present, their absence does not rule out M. minutoides. This cytotype has a large distribution, with specimens found in Tanzania and in the eastern part of South Africa. The nonpervasive distribution of Rb(X.1) provides an opportunity to investigate different evolutionary scenarios of sex-autosome translocations using a phylogenetic framework and the distribution of telomeric repeats. The results tend to support a scenario involving a reversal event, i.e., fusion then fission of Rb(X.1), and highlighted the existence of a new X₁X₁X₂X₂/X₁X₂Y sex chromosome system, confirming the remarkable diversity of neo-sex chromosomes and sex determination systems in the African pygmy mice.
Study Design
Biomechanical cadaveric study.
Objective
Clinical studies indicate that using less-rigid fixation techniques in place of the standard all-pedicle screw construct when correcting for ...scoliosis may reduce the incidence of proximal junctional kyphosis and improve patient outcomes. The purpose of this study is to investigate whether there is a biomechanical advantage to using supralaminar hooks in place of pedicle screws at the upper-instrumented vertebrae in a multilevel thoracic construct.
Methods
T7–T12 spines were biomechanically tested: (1) intact; (2) following a two-level pedicles screw fusion from T9 to T11; and after proximal extension of the fusion to T8–T9 with (3) bilateral supra-laminar hooks, (4) a unilateral hook + unilateral screw hybrid, or (5) bilateral pedicle screws. Specimens were nondestructively loaded while three-dimensional kinematics and intradiscal pressure at the supra-adjacent level were recorded.
Results
Supra-adjacent hypermobility was reduced when bilateral hooks were used in place of pedicle screws at the upper-instrumented level, with statistically significant differences in lateral bending and torsion (p < 0.05 and p < 0.001, respectively). Disk pressures in the supra-adjacent segment were not statistically different among top-off techniques.
Conclusions
The use of supralaminar hooks at the top of a multilevel posterior fusion construct reduces the stress at the proximal uninstrumented motion segment. Although further data is needed to provide a definitive link to the clinical occurrence of PJK, this in vitro study demonstrates the potential benefit of “easing” the transition between the stiff instrumented spine and the flexible native spine and is the first to demonstrate these results with laminar hooks.
A new volatile organic compounds (VOCs) sensing concept called humidity‐initiated gas (HIG) sensors is described and demonstrated. HIG sensors employ the impedance of water assembled at sensor ...interfaces when exposed to humidity to sense VOCs at low concentrations. Here, two HIG sensor variants are studied—Type I and Type II. Type I sensors benefit from simplicity, but are less attractive in terms of key performance metrics, including response time and detection limits. Type II sensors are more complex, but are more attractive in terms of key performance metrics. Notably, it is observed that the best‐in‐class Type II HIG sensors achieve <2 min response times and <10 ppb detection limit for geranyl acetone, a VOC linked to the asymptomatic form of Huanglongbing (HLB) citrus disease. Both Type I and Type II sensors are assembled from off‐the‐shelf materials and demonstrate remarkable stability at high humidity. HIG sensors are proposed as an attractive alternative to existing VOCs sensors for remote field detection tasks, including VOCs detection to diagnose HLB citrus disease.
A new volatile organic compounds (VOCs) sensing concept called humidity‐initiated gas (HIG) sensors is demonstrated. HIG sensors detect VOCs using the impedance of water vapor assembled at sensor interfaces. Two HIG sensor variants are described—Type I and Type II—that have different sensing characteristics. HIG sensors represent a potential alternative to existing VOCs sensors for remote field detection applications.
In 2010, the Cornell-USDA apple rootstock breeding program at Geneva, NY released 4 new apple root stocks (Geneva® 210, Geneva® 214, Geneva® 890 and Geneva® 969). G.210 is a semi-dwarfing rootstock ...with vigor similar to M.7, with high productivity similar to M.9 and resistance to fire blight, Phytophthora root rot, and woolly apple aphid. It has also shown tolerance to apple replant disease in field trials in New York and Washington. It is not free standing and requires a trellis for supporting the trees, which can lean under wet soils conditions. G.214 a fully dwarfing rootstock with vigor similar to M.9 with very high productivity and resistance to fire blight, Phytophthora root rot, and woolly apple aphid. It is easy to propagate in stoolbeds has shown tolerance to apple replant disease in field trials in New York and Washington. It is not free standing and requires a trellis. G.890 is a semi-dwarf rootstock with vigor similar to MM.111. It has high productivity (similar to M.26) and resistance to fire blight, Phytophthora root rot, and woolly apple aphid. It is easy to propagate in stoolbeds and is free standing in the orchard. G.969 is a semi-dwarfing rootstock with vigor similar to M.26 with very high productivity and resistance to fire blight, Phytophthora root rot, and woolly apple aphid. It is easy to propagate in stoolbeds. It is free standing in the orchard.
We report a novel and easily accessible method to chemically reduce graphene fluoride （GF） sheets with nanoscopic precision using high electrostatic fields generated between an atomic force ...microscope （AFM） tip and the GF substrate. Reduction of fluorine by the electric field produces graphene nanoribbons （GNR） with a width of 105-1,800 nm with sheet resistivity drastically decreased from 〉1 TΩ.sq.^-1 （GF） down to 46 kΩ.sq.^-1 （GNR）. Fluorine reduction also changes the topography, friction, and work function of the GF. Kelvin probe force microscopy measurements indicate that the work function of GF is 180-280 meV greater than that of graphene. The reduction process was optimized by varying the AFM probe velocity between 1.2 μm.s^-1 and 12 μm.s^-1 and the bias voltage applied to the sample between -8 and -12 V. The electrostatic field required to remove fluorine from carbon is -1.6 V.nm-1. Reduction of the fluorine may be due to the softening of the C-F bond in this intense field or to the accumulation and hydrolysis of adventitious water into a meniscus.
Older adults have reduced fluid intake and impaired body fluid and electrolyte regulation. Older female adults exhibit exaggerated exercise blood pressure (BP) responses, which is associated with an ...increased risk of adverse cardiovascular events. However, it is unclear if dysregulated body fluid homeostasis contributes to altered exercise BP responses in older female adults. We tested the hypothesis that short‐term water deprivation (WD) increases exercise BP responses in older female adults. Fifteen female adults (eight young 25 ± 6 years and seven older 65 ± 6 years) completed two experimental conditions in random crossover fashion; a euhydration control condition and a stepwise reduction in water intake over three days concluding with a 16‐hr WD period. During both trials, beat‐to‐beat BP (photoplethysmography) and heart rate (electrocardiogram) were continuously assessed during rest, handgrip exercise (30% MVC), and post‐exercise ischemia (metaboreflex isolation). At screening, older compared to young female adults had greater systolic and diastolic BP (p ≤ .02). Accelerometer‐assessed habitual physical activity was not different between groups (p = .65). Following WD, 24‐hr urine flow rate decreased, whereas thirst, urine specific gravity, and plasma osmolality increased (condition: p < .05 for all), but these WD‐induced changes were not different between age groups (interaction: p ≥ .31 for all). Resting systolic and diastolic BP values were higher in older compared to young adults (p < .01 for both), but were not different between experimental conditions (p ≥ .20). In contrast to our hypothesis, WD was associated with attenuated systolic BP responses during handgrip exercise (post hoc: p < .01) and post‐exercise ischemia (post hoc: p = .03) in older, but not young, female adults. These data suggest that reduced water intake‐induced challenges to body fluid homeostasis do not contribute to exaggerated exercise BP responses in post‐menopausal female adults.
The current data suggest that healthy female aging is associated with a maintained ability to preserve body water balance during short‐term reductions in water intake. These data also indicate that reduced water intake is not associated with augmented cardiovascular responses during exercise pressor reflex activation in older female adults.
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