The aim of this thesis is to use a cross-match between WISE, 2MASS and SDSS to identify a large sample of M dwarfs. Through the careful characterisation and quality control of these M dwarfs I aim to identify rare systems (i.e. unresolved UCD companions, young M dwarfs, late M dwarfs and M dwarfs with common proper motion companions). Locating ultracool companions to M dwarfs is important for constraining low-mass formation models, the measurement of substellar dynamical masses and radii, and for testing ultracool evolutionary models. This is done by using an optimised method for identifying M dwarfs which may have unresolved ultracool companions. To do this I construct a catalogue of 440 694 M dwarf candidates, from WISE, 2MASS and SDSS, based on optical- and near-infrared colours and reduced proper motion. With strict reddening, photometric and quality constraints I isolate a sub-sample of 36 898 M dwarfs and search for possible mid-infrared M dwarf + ultracool dwarf candidates by comparing M dwarfs which have similar optical/near-infrared colours (chosen for their sensitivity to effective temperature and metallicity). I present 1 082 M dwarf + ultracool dwarf candidates for follow-up. Using simulated ultracool dwarf companions to M dwarfs, I estimate that the occurrence of unresolved ultracool companions amongst my M dwarf + ultracool dwarf candidates should be at least four times the average for my full M dwarf catalogue. I discuss yields of candidates based on my simulations. The possible contamination and bias from misidentified M dwarfs is then discussed, from chance alignments with other M dwarfs and UCDs, from chance alignments with giant stars, from chance alignments with galaxies, and from blended systems (via visual inspection). I then use optical spectra from LAMOST to spectral type a subset of my M dwarf + ultracool dwarf candidates. These candidates need confirming as true M dwarf + ultracool dwarf systems thus I present a new method I developed to use low resolution near-infrared spectra which relies on two colour similar objects (one an excess candidate, one not) having very similar spectra. A spectral difference of these two colour similar objects should leave the signature of a UCD in the residual of their differences, which I look for using the difference in two spectral bands designed to identify UCD spectral features. I then present the methods used to identify other rare systems from my full M dwarf catalogue. Young M dwarfs were identified by measuring equivalent widths of Hα from the LAMOST spectra, and by measuring rotation periods from Kepler 2 light curves. I identify late M dwarfs photometrically (using reduced proper motion and colour cuts) and spectroscopically (using the LAMOST spectra with spectral indices from the literature). Also I present common proper motion analysis aimed at finding Tycho-2 primaries for my M dwarfs and look for physically separated M dwarf + M dwarf pairs (internally within my full M dwarf catalogue).

Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates. Among terrestrial species, abundances of a short-lived, winter-spring breeder increased markedly by an estimated 2375285% across time, while two larger spring-summer breeders with higher thermal preferences declined by up to 64%. Abundances of two arboreal species that occupy shaded and thus sheltered microhabitats fluctuated but did not decline systematically. Abundances of all species increased with precipitation at short lag times (151.5 yrs) likely due to enhanced food availability, but often declined after periods of high precipitation at longer lag times (254 yrs) likely due to predation and other biotic pressures. Although rising maximum daily temperatures (Tmax) are expected to drive global declines of lizards, associations with Tmax were variable and weak for most species. Instead, abundances of all species declined with rising daily minimum temperatures, suggesting degradation of cool refugia imposed widespread metabolic or other costs. Our results suggest climate warming and drying are having major impacts on lizard communities by driving declines of species with traits that augment exposure to abiotic extremes and by modifying species interactions. The complexity of patterns we report indicate that evaluating and responding to the influence of climate change on biodiversity must consider a broad array of ecological processes.

Namaqualand is a semi-desert area situated in the winter rainfall region of South Africa hosting the world’s richest succulent flora, and is one of only two arid areas to classify as a global hotspot of biodiversity. The Goegap Nature Reserve, east of Springbok, lies in the Upland Succulent Karoo. After all the livestock were removed and the reserve fenced in 1969, a long-term monitoring project was initiated to record possible vegetation changes under the reduced grazing pressure. The first monitoring was done in 1974 when two line transects, of 1 km each, were surveyed. These surveys have been repeated annually covering a period of more than 30 years. When the reserve was enlarged in 1990, five additional line transects were set out in highly degraded areas. The main aim of this study was therefore to determine whether any changes in the vegetation in terms of species composition, species richness and life form richness in the monitored line transects could be detected. Rainfall as possible force driving these changes was also examined. It was found that changes did indeed take place in the vegetation. The species composition revealed notable changes over the entire monitored period, specifically in the two longest established line transects, whereas in the case of the species richness changes were also detected, but to a lesser extent and not notable in terms of an overall increase or decrease in the number of species. These changes are referred to as fluctuations. Rainfall can be regarded as a definite environmental driving force, with the time, intensity and duration of importance, specifically to the annual species composition. Overall, the veld condition improved and continuous monitoring of the line transects on a regular basis should take place to improve our understanding of the complex dynamics of this ecosystem. Because the changes in species composition are reflected in changes in grazing capacity the results are of direct importance to the management of the wildlife on the reserve. / Dissertation (MSc)--University of Pretoria, 2010. / Plant Science / unrestricted

A SECOND UNIVERSE is a memoir-in-essays that traces the author’s coming of age and her pursuit of self-discovery, belonging, and healing in all its forms. The book opens in the past, diving into the lives of the author’s parents before she was born and shedding light on the many obstacles they overcame to bring her earth-side. Set against the backdrop of the Southern Utah deserts and the clarity the author finds in the natural world, these essays wind through the author’s different childhood homes, down the lonely and desolate road of a sister’s addiction, and into the darkness that comes as she braces for her father’s impending blindness. Similar to Brenda Miller’s LISTENING AGAINST THE STONE, this collection explores the inherent desire for human connection and spiritual insight that we search for in the places we live, the people we love, and the nature that surrounds us.

The problems of lack of potable water, food and electrical power in and around the desert environment are analysed and their solutions based on the utilisation of indigenous renewable energy resources are evaluated in the current research. Self-contained, decentralised solar energy powered processes are devised in the research results as means to attain the objectives of supplying electrical power, potable water and food to the communities living in the deserts in environmentally sustainable manner. Needs analysis of desert community, a questionnaire survey, desert energy model utilisation scenarios, solar potential assessment and environmental emissions reduction strategy are used as means of analysis in the current research. A potential assessment of a desert site Islamkot, at Thar is carried out to demonstrate the capability of available solar potential to meet the energy needs of underground pumping, desalination of aquifer water potable water, cultivation of wheat, rice and pulses and domestic power consumption. The needs analysis estimates the amounts of electrical power needs of potable water desalination, agricultural commodities cultivation and electrical power needs per person per day, which can be scale up for any number of communities living in and around the deserts. The results reveals that indigenous solar potential capability can be used to produce the required amounts of electrical power to meet the water, wheat, rice, pulses, electrical power, drinking, non-drinking and cultivation water needs of the desert communities in environmentally sustainable manner. The research results are practicable and can be implemented to meet the energy needs of isolated communities living in and around the deserts in the long run. However, sustainable efforts would be required to encourage stakeholders to initiate a process of small, medium and large scale solar power utilization in and around the deserts.

Scarabaeus (Pachysoma) consists of 13 flightless dung beetle species endemic to the arid west coast of southern Africa. Scarabaeus (Pachysoma) are unique in their feeding and foraging habits, in that they randomly search for dry dung/detritus which, when found, is dragged forwards, and buried in a pre-constructed holding chamber, as opposed to the convention of rolling it backwards. This action is repeated to provision the chamber after which the nest is expanded to below the moisture line to allow the stored food to re-hydrate. Poor vagility, taxonomic contention - seen in Scarabaeus taxonomy - and conservation concern, made Scarabaeus (Pachysoma) an ideal group of beetles to study both the phylogenetics and potential influences that anthropogenic and environmental changes have had on structuring the species and populations thereof. Both molecular and morphological data were used as individual datasets and combined in a total evidence approach. Biogeographic inferences were made based on recent detailed Namib biogeography and the ages of the species were estimated using the molecular clock method. A phylogeographic study was done on three of the species of Scarabaeus (Pachysoma) – S. (P.) hippocrates, S. (P.) gariepinus and S. (P.) denticollis - that had previously shown south-north morphological clinal variation. Lastly, an attempt was made to isolate microsatellite loci for Scarabaeus, in the hope of characterising genetic diversity within and between populations of the same species. Scarabaeus (Pachysoma) was found to be monophyletic within Scarabaeus and was therefore classified as a derived subgenus thereof. Morphologically Scarabaeus (Pachysoma) was shown to have 13 species while at a molecular level strong resolution for 11 of the 13 was obtained. S. (P.) hippocrates and S. (P.) glentoni formed a species complex the hippocrates/glentoni complex. The combined phylogenetic tree showed good overall support for all 13 species. Both the morphological and molecular data partition phylogenies show congruence with the combined phylogeny, lending support for combining datasets. Scarabaeus (Pachysoma) appears to have arisen 2.9 million years ago. The formation of advective fog is a consistent water source for Desert dwelling organisms and appears to be associated with Scarabaeus (Pachysoma) radiation into inhospitable areas. Analysis of gene flow revealed large amounts of south-north movement, lending support for movement of psammophilous taxa with their substratum, the barchan dune. Population demographics of the three species, S. (P.) hippocrates, S. (P.) gariepinus and S. (P.) denticollis, chosen for this study differed greatly except in areas of geographic similarity. Major rivers appear to have acted as gene barriers, allowing for distinct genetic entities to be identified within the three species. Phylogeographic partitioning was supported by an AMOVA analysis. All three species were shown to have undergone historical population expansion dating back to the Pleistocene era. Nested Clade Analysis indicated that allopatric speciation; isolation by distance and continuous range expansion could be the factors having affected overall population structure. Recent events show that human induced factors, environmental barriers and reduced vagility have influenced the species population structure. Four potentially polymorphic loci were isolated for Scarabaeus using the FIASCO protocol. Identification of at least one additional locus is needed in order to obtain statistical significance for future studies directed at uncovering recent population dynamics. / Thesis (PhD (Entomology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

Föreliggande arbete tar sin utgångspunkt i en observation av hur United States Marine Corps (USMC) använde pansarvärnsrobotförband förvånansvärt aggressivt under Gulfkriget 1991. Med syftet att studera denna taktik och att därigenom skapa en ökad förståelse för pansarvärnsrobotförbandens taktiska möjligheter/begränsningar skapas en problemformulering som undersöker vilken relevans USMC:s taktik med pansarvärnsrobotförband i Operation DESERT STORM har för svenska armén idag? För att kunna besvara denna övergripande fråga bryts den ned till tre forskningsfrågor som beskriver vilken taktik som karaktäriserade USMC:s pansarvärnsrobotförband, därefter förklarar motiven för denna taktik och slutligen värderar vilka lärdomar som svenska armén kan dra från detta 2012. Resultatet visar att marinkårens taktik i huvudsak har låg relevans på grund av de unika förutsättningar avseende terräng, siktförhållanden och teknikasymmetri som förelåg i Persiska viken 1991. Terrängen var nästan helt platt vilket gav god effekt för pansarvärnsrobotarnas övertag i skjutavstånd gentemot irakiska stridsvagnar. Oljerök och dimma gjorde att deras termiska sikten kunde verka där inga irakiska motsvarigheter fanns. Konceptet Combined Anti Armor Team bedöms värt att beakta för armén inom ramen för kombinerade vapen och slutförande av Insatsorganisation 2014.

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