Evaluating drought response of Southern Cape Indigenous Forests,South Africa,using MODIS data

Indigenous forests in South Africa cover less than 0.5% of the total land area but are a valued resource under threat from fragmentation, fires, exploitation, and climate change. The largest indigenous forest complex is located along the southern coast of the Western Cape Province. This complex is made up of sub-forests distinguished by different structural and edaphoclimatic attributes. It has been hypothesized that these sub-forests exhibit different resistance to stressors, such as drought. A time series of MODIS 250 m enhanced vegetation index (EVI) data were used to characterize the foliage condition of the three distinctive sub-forests before, during, and after a severe drought in 2009. The goal was to determine how these sub-forests responded to this disturbance. EVI anomalies for the drought and post-drought periods were calculated using annual median EVI values, since removal of outliers based on quality control flags that accompany the MODIS products or noise-filtering techniques proved to be ineffective. Results of the study indicated that pre-drought foliage density EVI was not controlled by differences in water availability, but may have been due to other edaphoclimatic or structural attributes. Maximum foliage loss occurred one year after the driest year, indicating the cumulative effects of drought stress on forest production and retention of foliage. The hypothesized stress resistance capacity of the three sub-forests was found to correspond to their rate of post-drought recovery. There is a need to tie these satellite observations of forest drought response to ground observations of forest condition, growth, and specific site attributes.     

Do our methods lead to insomniacs' madness?: Daytime testing after laboratory and home-based polysomnographic studies

Complaints of daytime dysfunction are common among chronic insomniacs, but laboratory comparisons of insomniacs and age-matched and gender-matched normal controls have generally failed to document these complaints. However, a few studies, which allowed subjects to sleep in their homes on the nights before daytime testing, have shown some relative diurnal deficits among insomniacs. The current study compared the effects of nocturnal laboratory and home polysomnogram (PSG) studies on subsequent daytime test results among older insomniacs and normal sleepers. Insomniacs (n = 32) and normal sleepers (n = 32) were randomly assigned to first undergo three nights of nocturnal PSG monitoring either in the sleep laboratory (16 insomniacs, 16 normal sleepers) or in their homes (16 insomniacs, 16 normal sleepers). Following the third night of PSG monitoring, subjects spent 1 day in the sleep laboratory, where they completed a four-trial multiple sleep latency test along with four trials of a computer-administered performance test battery. Results showed that insomniacs, as a group, were slightly, albeit consistently, sleepier than were normal sleepers following nights of home sleep monitoring, but a reverse of this trend was found among subjects who underwent nocturnal laboratory PSG before daytime testing. Furthermore, normal sleepers showed faster reaction times on a signal detection task than did insomniacs within the subgroup who underwent home PSGs prior to such testing. However, within the subgroup that underwent nocturnal laboratory PSGs, insomniacs' signal detection reaction times were significantly faster than those shown by normal sleepers. Results provide some support for the speculation that the nocturnal PSG monitoring site, used as a precursor to daytime testing, may systematically affect daytime comparisons between insomniacs and matched controls. Moreover, these results suggest that the use of home-based nocturnal PSG monitoring prior to daytime testing may provide an enhanced understanding of insomniacs' diurnal complaints.     

Modelling mobile multimedia services

Future multimedia and Internet services will have more complex characteristics than the traditional service types. Accurate planning of mobile networks requires accurate prediction of traffic flows, which involves complex relationships between the services themselves, the mobility of users, and the business environment. This paper describes the work of the Mobile VCE services programme on new traffic models that take all three factors into account     

Cerebrovascular effects of analgosedation

The in vitro drug sensitivity of three dihydrofolate reductase inhibitors (pyrimethamine, cycloguanil, trimethoprim) was determined against 29 strains and isolates of Plasmodium falciparum by an isotopic semi-microtest. Trimethoprim is less active than pyrimethamine or cycloguanil and its activity is correlated with that of two other inhibitors, suggesting cross-resistance in vitro among the dihydrofolate reductase inhibitors.     

Identification and characterization of the PutP proline permease that contributes to in vivo survival of Staphylococcus aureus in animal models

Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscesses, endocarditis, and other infectious syndromes. A signature-tagged mutagenesis (STM) system was adapted for use in studying the genes required for in vivo survival of S. aureus. An STM library was ultimately created in S. aureus RN6390, with Tn917 being used to create the transposon mutations. Pools of S. aureus RN6390 mutants were screened in mouse abscess, bacteremia, and wound infection models for growth attenuation after in vivo passage. One of the mutants that was identified displayed marked attenuation following large-pool screening in all three animal models, which was confirmed in bacteremia and endocarditis models of infection with a smaller pool of mutants. Sequence analysis of the entire open reading frame showed a 99% identity to the high-affinity proline permease (putP) gene characterized in another strain of S. aureus. In wound and murine abscess infection models, the putP mutant was approximately 10-fold more attenuated than was wild-type strain RN6390. Another S. aureus strain transduced with the putP mutation also displayed an attenuated phenotype after passage in the wound model. A [3H]proline uptake assay showed that less proline was specifically transported into the putP mutant than into strain RN6390. The reduced viability of the bacteria possessing the mutation in the S. aureus high-affinity proline permease suggests that proline scavenging by the bacteria is important for in vivo growth and proliferation and that analogs of proline may serve as potential antistaphylococcal therapeutic agents.     

Modification of a receptor-binding surface of epidermal growth factor (EGF): analogs with enhanced receptor affinity at low pH or at neutrality

Six mutants of human epidermal growth factor (EGF), which carry singlepoint substitutions within a surface patch proposed to juxtapose the boundreceptor, were prepared and characterized for receptor affinity andmitogenicity. Receptor affinities relative to EGF are G12Q > H16D >Y13W > Q43A approximately = H16A approximately = EGF >> L15A.Notably, the reduced receptor affinity of mutant L15A indicates that Leu15probably contributes substantially to receptor binding whereas unalteredreceptor affinities observed for analogs H16A and Q43A indicate thatneither His16 nor Gln43 contributes significantly to this interaction. Onthe other hand, the observed enhanced receptor affinities of analogs G12Q,Y13W and H16D highlight surface loci where additional productivereceptor-binding contacts can be introduced. Interestingly, at acidic pHanalog H16A reveals substantially greater receptor affinity than that ofEGF, a property which may offer enhanced therapeutic utility in acidicenvironments in vivo.     

Renaturation of formyltetrahydrofolate synthetase from urea and guanidinium chloride solutions

Formyltetrahydrofolate synthetase from Clostridium cylindrosporum and Clostridium acidi-urici was denatured in 6 M urea and 4 M guanidinium chloride. Viscometric, fluorimetric and ultracentrifugal measurements were used to determine that the protein is completely unfolded under these conditions. The polypeptide chains refold upon dilution of the denaturant-protein solutions to give final concentrations of 0.5 M urea or 0.1 M guanidinium chloride. In the presence of NH4+, but not in its absence, the refolded proteins associate to produce the catalytically active tetramer. Refolding and reassociation were followed by measuring changes in protein fluorescence and by determination of sedimentation constants. Under most conditions 80% of the enzymic activity is recovered.