Effects of landscape gradients on wetland vegetation communities: information for large-scale restoration

Projects of the scope of the restoration of the Florida Everglades require substantial information regarding ecological mechanisms, and these are often poorly understood. We provide critical base knowledge for Everglades restoration by characterizing the existing vegetation communities of an Everglades remnant, describing how present and historic hydrology affect wetland vegetation community composition, and documenting change from communities described in previous studies. Vegetation biomass samples were collected along transects across Water Conservation Area 3A South (3AS)

Vibrotactile pattern recognition on the torso : effects of concurrent activities

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 25).Vibrotactile displays have been created to aid vision or hearing through the sense of touch. These displays communicate with the user to provide information. The focus of this thesis was to determine how concurrent activity affects vibrotactile signal recognition. An overall accuracy recognition rate of 90% or greater was desired from each of the signals in the each of the tasks. The first experiment asked subjects to wear the tactile display and walk while responding to signals. The results indicated that most of the subjects were able to recognize the patterns. The overall mean correct response rate was 92% and then when the subjects were asked to jog, they correctly identified the patterns 91% of the time. After determining the success rates from the first experiment, a second set of subjects were asked to concentrate on an internet game while responding to signals. The data from this experiment had an overall mean correct response rate of 93%. The results from this experiment further indicate that subjects can still receive communications while participating in other activities. The results also lead to specific conclusions about the patterns used and their ability to be identified with concurrent activity where some patterns are more easily received than others. By understanding how these patterns are recognized by humans, we can better develop patterns to communicate through tactile devices.by Christa M. Margossian.S.B

Physiological Mechanisms of Desiccation Resistance in Fruit-Parasitic Rhagoletis Flies

Understanding drought adaptation in fruit-parasitic Rhagoletis flies is essential for evaluating the potential for eastward spread of the invasive apple maggot fly, R. pomonella, from coastal Washington into arid central Washington, which poses a threat to the largest crop of U.S. apples. A closely related native species, R. zephyria, provides an opportunity to study existing drought adaptation in the region as it is locally adapted to drought conditions in central Washington. Here, I aim to elucidate physiological mechanisms underlying desiccation resistance in R. pomonella and R. zephyria, as well as determine if the trait is plastic or canalized in R. zephyria. Pupal diapause could be an advantageous state under drought stress because metabolisms are suppressed, limiting active water loss. To test diapause regulation as a mechanism contributing to desiccation resistance, I observed the proportions of diapausers (vs. direct developers) under high (drought) and low (non-drought) vapor pressure deficits in three host races of invasive R. pomonella and two populations of native R. zephyria to determine if 1) there was past selection on diapause regulation that led to higher proportions of diapausers in drought resistant populations and 2) drought stress affected diapause regulation. R. zephyria lacked direct development completely so diapause regulation cannot account for greater desiccation resistance in populations from arid vs. humid regions in Washington. The proportions of diapausers in R. pomonella were greatest among black hawthorn infesting flies (high desiccation resistance) and similar between apple infesting flies (low desiccation resistance) and ornamental hawthorn infesting flies (intermediate desiccation resistance), and not affected by drought treatment, suggesting diapause regulation is not the primary mechanism contributing to desiccation resistance in the invasive species. Next, I conducted a differential gene expression experiment to explore additional mechanisms and to categorize canalized versus plastic transcriptional responses to drought stress. Gene expression in newly egressed R. zephyria larvae was largely canalized in drought resistant and susceptible populations, though drought resistant larvae responded more to low humidity conditions (relative to humid conditions) than drought susceptible larvae, suggesting that local drought adaptation in R. zephyria is impacted by a genotype x environment interaction. Annotation of differentially expressed genes suggest differences in cuticular hydrocarbon profiles could underlie variable desiccation resistance and highlighted potential differences in development speeds between populations. In conclusion, desiccation resistance in R. zephyria and R. pomonella is likely multi-faceted and the primary mechanism that accounts for variation in desiccation resistance among populations is yet to be identified. Furthermore, desiccation resistance appears to be adaptive to local climates in R. zephyria and potentially constrained by host related fitness tradeoffs in R. pomonella

Employment equity in Canada and South Africa: a comparative review

The South African Government has sought to redress the historical legacy of workplace discrimination by introducing the Employment Equity Act (1998), which was largely modeled on the Canadian Employment Equity Act. Although there is very little comparative information between South Africa and Canada, we fill this gap by reviewing the literature in both countries, highlighting common features of the legislation, discussing the effectiveness of legislation in both countries as well as the progress made by the designated groups covered by the legislation. This paper provides a background on the rationale for employment equity and associated human resource management policies in both Canada and South Africa. The analysis is largely based on institutional theories of organizations. Our evaluation provides overall conclusions for policy makers and organizational leaders, taking into consideration socio-historical, political, and demographic differences between the jurisdictions. Issues include top management commitment, organizational culture, Black economic empowerment, and diversity policies and practice

On inferring extinction laws in z~6 quasars as signatures of supernova dust

Unusual extinction curves of high-redshift QSOs have been taken as evidence that dust is primarily produced by supernovae at high redshift. In particular, the 3000 A Todini-Ferrara-Maiolino kink in the extinction curve of the z = 6.20 SDSS J1048+4637 has been attributed to supernova dust. Here we discuss the challenges in inferring robust extinction curves of high-redshift QSOs and critically assess previous claims of detection of supernova dust. In particular, we address the sensitivity to the choice of intrinsic QSO spectrum, the need for a long wavelength baseline, and the drawbacks in fitting theoretical extinction curves. In a sample of 21 QSOs at z ~ 6 we detect significant ultraviolet extinction using existing broad-band optical, near-infrared, and Spitzer photometry. The median extinction curve is consistent with a Small Magellanic Cloud curve with A_1450 ~ 0.7 mag and does not exhibit any conspicuous (restframe) 2175 A or 3000 A features. For two QSOs, SDSS J1044-0125 at z = 5.78 and SDSS J1030+0524 at z = 6.31, we further present X-shooter spectra covering the wavelength range 0.9-2.5 um. The resulting non-parametric extinction curves do not exhibit the 3000 A kink. Finally, in a re-analysis of literature spectra of SDSS J1048+4637, we do not find evidence for a conspicuous kink. We conclude that the existing evidence for a 3000 A feature is weak and that the overall dust properties at high and low redshift show no significant differences. This, however, does not preclude supernovae from dominating the dust budget at high redshift.Comment: 13 pages, 13 figures, ApJ, in pres

Wiretapping the Internet: The Expansion of the Communications Assistance to Law Enforcement Act to Extend Government Surveillance

Criminal use of the Internet to circumvent traditional government phone wiretaps has inspired the Obama Administration to create a proposal to expand the Communications Assistance to Law Enforcement Act ( CALEA ). CALEA was passed in 1994 to regulate telephone and broadband companies to ensure compliance with standards to enable government wiretapping. The proposed amendment of CALEA would allow the government to require all communications service providers to meet technical standards necessary to comply with a wiretap order. The expansion of CALEA would likely widen its scope to social networking sites, instant messaging, gaming consoles that allow conversation among multiple players, and to word processing software that allows communication through Internet access. The unique architecture of the Internet lends it to particular vulnerabilities with the consequence that an expansion of CALEA to all Internet communications could create problems regarding the innovative nature of the Internet, national security, free speech, and privacy. This Note will examine the competing interests related to expanding CALEA and will weigh the potential benefits and consequences of CALEA. The Note concludes that substantially more information is needed to justify a change of the law

Wiretapping the Internet: The Expansion of the Communications Assistance to Law Enforcement Act to Extend Government Surveillance

Criminal use of the Internet to circumvent traditional government phone wiretaps has inspired the Obama Administration to create a proposal to expand the Communications Assistance to Law Enforcement Act ( CALEA ). CALEA was passed in 1994 to regulate telephone and broadband companies to ensure compliance with standards to enable government wiretapping. The proposed amendment of CALEA would allow the government to require all communications service providers to meet technical standards necessary to comply with a wiretap order. The expansion of CALEA would likely widen its scope to social networking sites, instant messaging, gaming consoles that allow conversation among multiple players, and to word processing software that allows communication through Internet access. The unique architecture of the Internet lends it to particular vulnerabilities with the consequence that an expansion of CALEA to all Internet communications could create problems regarding the innovative nature of the Internet, national security, free speech, and privacy. This Note will examine the competing interests related to expanding CALEA and will weigh the potential benefits and consequences of CALEA. The Note concludes that substantially more information is needed to justify a change of the law

The Social and Material Lives of the Agricultural Elite: The18th-Century Tyngs of Dunstable, Massachusetts

The Tyngs were a wealthy family in Dunstable (now Tyngsborough), Massachusetts in the late- 17th and 18th centuries. They were descended from a Boston merchant, and maintained many commercial connections. Some members of the family became rural storekeepers in Dunstable. Historical research and archaeological data from Eleazer Tyng\u27s house site show the different ways in which the Tyngs related themselves to the urban coastal elite, and participated in the culture of gentility and refinement. Through architecture, social connections, and material goods such as tea wares, they lived as rural elites with connections to the coast. Rather than directly mimicking the life of Boston elites, the Tyngs adapted gentility to their rural life and agrarian base