The Red Queen visits Minkowski Space

When Alice went `Through the Looking Glass' [1], she found herself in a situation where she had to run as fast as she could in order to stay still. In accordance with the dictum that truth is stranger than fiction, we will see that it is possible to find a situation in special relativity where running towards one's target is actually counter-productive. Although the situation is easily analysed algebraically, the qualitative properties of the analysis are greatly illuminated by the use of space-time diagrams

The construction and evaluation of an instrument to determine the sports knowledge of boys from grades nine through twelve,

Thesis (M.A.)--Boston Universit

Use of multiple singular value decompositions to analyze complex intracellular calcium ion signals

We compare calcium ion signaling ($\mathrm {Ca}^{2+}$) between two exposures; the data are present as movies, or, more prosaically, time series of images. This paper describes novel uses of singular value decompositions (SVD) and weighted versions of them (WSVD) to extract the signals from such movies, in a way that is semi-automatic and tuned closely to the actual data and their many complexities. These complexities include the following. First, the images themselves are of no interest: all interest focuses on the behavior of individual cells across time, and thus, the cells need to be segmented in an automated manner. Second, the cells themselves have 100$+$ pixels, so that they form 100$+$ curves measured over time, so that data compression is required to extract the features of these curves. Third, some of the pixels in some of the cells are subject to image saturation due to bit depth limits, and this saturation needs to be accounted for if one is to normalize the images in a reasonably unbiased manner. Finally, the $\mathrm {Ca}^{2+}$ signals have oscillations or waves that vary with time and these signals need to be extracted. Thus, our aim is to show how to use multiple weighted and standard singular value decompositions to detect, extract and clarify the $\mathrm {Ca}^{2+}$ signals. Our signal extraction methods then lead to simple although finely focused statistical methods to compare $\mathrm {Ca}^{2+}$ signals across experimental conditions.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS253 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Preservation Pending: The Future of E-book Access in the Digital Age

For a very long time human knowledge has been recorded on print media and passed down, or preserved, for future generations. Since the latter half of the Twentieth Century however this human knowledge has been increasingly recorded in digital media. Whether we will be as successful as our predecessors at preserving human knowledge will depend on the steps we take now to identify and address the risks and threats when knowledge is stored in digital form. This report will focus specifically on e-books as a subset of all digital media. In some respects we are lucky in that the conversation surrounding the risks and threats to journal literature as it passed from print to digital has been going on for more than two decades, and some promising models and ideas have emerged. On the other hand e-books present problems that differ from those on the journal side and which will need to be addressed from scratch, as it were, with no prior models on which to build. Nor will this report provide ready answers. Rather, by bringing the conversation here we are throwing down the gauntlet and challenging all members of the information ecosystem to think seriously about the issues and to take the steps necessary to work toward a solution that is of mutual benefit to us all

Avian taxonomic and functional diversity in early stage of longleaf pine (Pinus palustris) stands restored at agricultural lands: Variations in scale dependency

In agricultural landscapes, the Longleaf Pine Initiative (LLPI) and the Bobwhite Quail Initiative (BQI) aim to restore longleaf pine forests and early successional habitats, respectively. The early stage of longleaf pine stands and grass and forb vegetation produced by a combination of both restoration programs (LLPI-BQI) may form habitat conditions favorable to early successional bird species and other birds, increasing avian diversity. We investigated how the LLPI and BQI programs affected taxonomic and functional diversity of birds and abundance of early successional birds (grassland and scrub/shrub species), and what environmental characteristics were associated with the diversity and abundance of birds. Our study was performed at 41 fields in Georgia, USA, during 2001-2002 by considering environmental characteristics at two spatial scales: local-scale vegetation features and restoration program type (LLPI or LLPI-BQI) and landscape-scale vegetation features and landscape heterogeneity. Functional evenness, species richness, and abundance of grassland and scrub/shrub species did not show a clear association with local- or landscape-scale variables. Shannon-Wiener diversity was slightly influenced by restoration program type (local-scale variable) with higher value at LLPI-BQI stands than at LLPI stands despite no significant differences in local vegetation features between those stands. Functional divergence was strongly positively associated with landscape-scale variables. That is, niche differentiation increased with increasing shrub coverage within a landscape, reducing competition between abundant bird species and others. Our results suggest that although a combination of BQI and LLPI program may have a positive effect on avian taxonomic diversity, it is important to consider shrub vegetation cover within a landscape to improve functional diversity

Avian taxonomic and functional diversity in early stage of longleaf pine (Pinus palustris) stands restored at agricultural lands: Variations in scale dependency

In agricultural landscapes, the Longleaf Pine Initiative (LLPI) and the Bobwhite Quail Initiative (BQI) aim to restore longleaf pine forests and early successional habitats, respectively. The early stage of longleaf pine stands and grass and forb vegetation produced by a combination of both restoration programs (LLPI-BQI) may form habitat conditions favorable to early successional bird species and other birds, increasing avian diversity. We investigated how the LLPI and BQI programs affected taxonomic and functional diversity of birds and abundance of early successional birds (grassland and scrub/shrub species), and what environmental characteristics were associated with the diversity and abundance of birds. Our study was performed at 41 fields in Georgia, USA, during 2001-2002 by considering environmental characteristics at two spatial scales: local-scale vegetation features and restoration program type (LLPI or LLPI-BQI) and landscape-scale vegetation features and landscape heterogeneity. Functional evenness, species richness, and abundance of grassland and scrub/shrub species did not show a clear association with local- or landscape-scale variables. Shannon-Wiener diversity was slightly influenced by restoration program type (local-scale variable) with higher value at LLPI-BQI stands than at LLPI stands despite no significant differences in local vegetation features between those stands. Functional divergence was strongly positively associated with landscape-scale variables. That is, niche differentiation increased with increasing shrub coverage within a landscape, reducing competition between abundant bird species and others. Our results suggest that although a combination of BQI and LLPI program may have a positive effect on avian taxonomic diversity, it is important to consider shrub vegetation cover within a landscape to improve functional diversity

Effect of silver content on the structure and antibacterial activity of silver-doped phosphate-based glasses

Staphylococcus aureus can cause a range of diseases, such as osteomyelitis, as well as colonize implanted medical devices. In most instances the organism forms biofilms that not only are resistant to the body's defense mechanisms but also display decreased susceptibilities to antibiotics. In the present study, we have examined the effect of increasing silver contents in phosphate-based glasses to prevent the formation of S. aureus biofilms. Silver was found to be an effective bactericidal agent against S. aureus biofilms, and the rate of silver ion release (0.42 to 1.22 µg·mm–2·h–1) from phosphate-based glass was found to account for the variation in its bactericidal effect. Analysis of biofilms by confocal microscopy indicated that they consisted of an upper layer of viable bacteria together with a layer (20 µm) of nonviable cells on the glass surface. Our results showed that regardless of the silver contents in these glasses (10, 15, or 20 mol%) the silver exists in its +1 oxidation state, which is known to be a highly effective bactericidal agent compared to that of silver in other oxidation states (+2 or +3). Analysis of the glasses by 31P nuclear magnetic resonance imaging and high-energy X-ray diffraction showed that it is the structural rearrangement of the phosphate network that is responsible for the variation in silver ion release and the associated bactericidal effectiveness. Thus, an understanding of the glass structure is important in interpreting the in vitro data and also has important clinical implications for the potential use of the phosphate-based glasses in orthopedic applications to deliver silver ions to combat S. aureus biofilm infections

Activated lymphocyte recruitment into the tumor microenvironment following preoperative sipuleucel-T for localized prostate cancer.

BackgroundSipuleucel-T is a US Food and Drug Administration-approved immunotherapy for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Its mechanism of action is not fully understood. This prospective trial evaluated the direct immune effects of systemically administered sipuleucel-T on prostatic cancer tissue in the preoperative setting.MethodsPatients with untreated localized prostate cancer were treated on an open-label Phase II study of sipuleucel-T prior to planned radical prostatectomy (RP). Immune infiltrates in RP specimens (posttreatment) and in paired pretreatment biopsies were evaluated by immunohistochemistry (IHC). Correlations between circulating immune response and IHC were assessed using Spearman rank order.ResultsOf the 42 enrolled patients, 37 were evaluable. Adverse events were primarily transient, mild-to-moderate and infusion related. Patients developed T cell proliferation and interferon-γ responses detectable in the blood following treatment. Furthermore, a greater-than-three-fold increase in infiltrating CD3(+), CD4(+) FOXP3(-), and CD8(+) T cells was observed in the RP tissues compared with the pretreatment biopsy (binomial proportions: all P < .001). This level of T cell infiltration was observed at the tumor interface, and was not seen in a control group consisting of 12 concurrent patients who did not receive any neoadjuvant treatment prior to RP. The majority of infiltrating T cells were PD-1(+) and Ki-67(+), consistent with activated T cells. Importantly, the magnitude of the circulating immune response did not directly correlate with T cell infiltration within the prostate based upon Spearman's rank order correlation.ConclusionsThis study is the first to demonstrate a local immune effect from the administration of sipuleucel-T. Neoadjuvant sipuleucel-T elicits both a systemic antigen-specific T cell response and the recruitment of activated effector T cells into the prostate tumor microenvironment

The Effects of Fatigue on Driver Performance for Single and Team Long-Haul Truck Drivers

Driver fatigue is an important safety issue for long-haul truck drivers. To provide an efficient means of obtaining sleep, long-haul truck drivers often use tractors equipped with sleeper berth units. Depending on the type of cargo and distances traveled, long-haul truck drivers either drive in teams or alone as single drivers. Team drivers, therefore, typically sleep in a moving truck whereas single drivers sleep in a stationary truck. It has been hypothesized that sleeping in a moving truck could adversely affect the sleep quality and, therefore, the alertness level of team drivers. A naturalistic data collection system was developed and installed in two Class 8 heavy trucks. This trigger-based system consisted of vehicle sensors and cameras that allowed the experimenters to obtain the driving performance and driver alertness data for analysis of fatigue. Fatigue was measured using both objective and subjective measures that were recorded before and after sleep and while driving. Fatigue and driving performance were compared for single versus team drivers to determine which driver type acquired the greatest sleep deficit during a trip. Results suggest that single drivers were more frequently involved in critical incidents while exhibiting extreme drowsiness than were team drivers by a factor of 4 to 1. These results will be discussed in relation to the general safety of single versus team trucking operations