The Spectra of Large Toeplitz Band Matrices with a Randomly Perturbed Entry

This report is concerned with the union $sp_{\Omega}^{(j,k)}T_{n}(a)$ of all possible spectra that may emerge when perturbing a large $n \times n$ Toeplitz band matrix $T_{n}(a)$ in the $(j,k)$ site by a number randomly chosen from some set $\Omega$. The main results give descriptive bounds and, in several interesting situations, even provide complete identifications of the limit of $sp_{\Omega}^{(j,k)}T_{n}(a)$ as $n \to \infty$. Also discussed are the cases of small and large sets $\Omega$ as well as the "discontinuity of the infinite volume case", which means that in general $sp_{\Omega}^{(j,k)}T_{n}(a)$ does not converge to something close to $sp_{\Omega}^{(j,k)}T_{n}(a)$ as $n \to \infty$, where $T(a)$ is the corresponding infinite Toeplitz matrix. Illustrations are provided for tridiagonal Toeplitz matrices, a notable special case. \ud \ud The second author was supported by UK Enginering and Physical Sciences Research Council Grant GR/M1241

Whipping up an Online Research Profile: How to Promote & Manage Your Research for Improved Science Communication

Creating and sustaining an online research profile can serve as an effective strategy for promoting and sharing one’s own work, finding and connecting with other researchers that have complementary research interests, and increasing the visibility and potential impact of one’s own research to the public overall. This workshop will introduce and discuss both new and traditional online research profile tools, such as ORCiD, Publons, Academia.edu, Twitter, etc., and will provide participants with a hands-on opportunity to work with these tools in small groups

On large Toeplitz band matrices with an uncertain block

This report investigates the possible spectra of large, finite dimensional Toeplitz band matrices with perturbations (impurities, uncertainties) in the upper-left m x m block. The main result shows that the asymptotic spectrum of such a matrix is not affected by these perturbations, provided they have sufficiently small norm. This follows from analysis of structured pseudospectra (structured spectral value sets). In contrast, for typical non-Hermitian Toeplitz matrices there exist certain rank-one perturbations of arbitrarily small norm that move an eigenvalue away from the asymptotic spectrum in the large-dimensional limit

Creators for the Earth: The Academic Library’s Role in Supporting Sustainability Creators and Practitioners Across All Disciplines

The image of a creator often brings to mind individuals that can take an abstract or unique idea and transform it into an impressive, tangible creation. Whether it’s an architect crafting a new building design, an artist painting on canvas, or an interior designer mapping out a new room layout, creators are generally seen as those who can formulate conceptual ideas that are then realized to showcase amazing ingenuity. In the world of higher education, this type of work is often first associated with disciplines like art, design, architecture, and engineering—fields where acts of “making,” “creating,” or “building” are integral to their purposes. However, this chapter invites readers to think beyond these more well-established creator fields to consider another field where creators are equally needed, supported, and produced: the field of sustainability and sustainable development

The Different Flavors of Research Impact: A Tasting of Traditional and Alternative Bibliometric Assessment Tools

This workshop introduces researchers to a variety of traditional and alternative bibliometric assessment tools. These metric tools are each defined and their potential uses, abuses, benefits, and drawbacks discussed. Researchers are then shown how to effectively utilize these metric tools to best fit their personal research needs and assess their research impact

Ewing Sarcoma Protein Ewsr1 Maintains Mitotic Integrity and Proneural Cell Survival in the Zebrafish Embryo

BACKGROUND:The Ewing sarcoma breakpoint region 1 gene (EWSR1), also known as EWS, is fused to a number of different partner genes as a result of chromosomal translocation in diverse sarcomas. Despite the involvement of EWSR1 in these diverse sarcomas, the in vivo function of wild type EWSR1 remains unclear. PRINCIPAL FINDINGS:We identified two zebrafish EWSR1 orthologues, ewsr1a and ewsr1b, and demonstrate that both genes are expressed maternally, and are expressed ubiquitously throughout zebrafish embryonic development. Morpholino induced knockdown of both zebrafish ewsr1 genes led to mitotic defects with multipolar or otherwise abnormal mitotic spindles starting from the bud stage (10 hour post-fertilization (hpf)). The abnormalities in mitotic spindles were followed by p53-mediated apoptosis in the developing central nervous system (CNS) leading to a reduction in the number of proneural cells, disorganization of neuronal networks, and embryonic lethality by 5 days post-fertilization. siRNA silencing of EWSR1 in Hela cells resulted in mitotic defects accompanied by apoptotic cell death, indicating that the role of EWSR1 is conserved between zebrafish and human. CONCLUSIONS:Ewsr1 maintains mitotic integrity and proneural cell survival in early zebrafish development

A qualitative investigation into knowledge, beliefs, and practices surrounding mastitis in sub-Saharan Africa: what implications for vertical transmission of HIV?

BACKGROUND: Mastitis constitutes an important risk factor in HIV vertical transmission. Very little, however, is known on how women in sub-Saharan Africa conceptualise health problems related to breastfeeding, such as mastitis, and how they act when sick. We aimed at filling this gap in knowledge, by documenting the indigenous nosography of mastitis, health seeking behaviour, and remedies for prophylaxis and treatment in rural sub-Saharan Africa. METHODS: The study was conducted in the Nouna Health District, rural Burkina Faso. We employed a combination of in-depth individual interviews and focus group discussions reaching both women and guérisseuers. All material was transcribed, translated, and analysed inductively, applying data and analyst triangulation. RESULTS: Respondents perceived breast problems related to lactation to be highly prevalent and described a sequence of symptoms which resembles the biomedical understanding of pathologies related to breastfeeding, ranging from breast engorgement (stasis) to inflammation (mastitis) and infection (breast abscess). The aetiology of disease, however, differed from biomedical notions as both women and guerisseurs distinguished between "natural" and "unnatural" causes of health problems related to breastfeeding. To prevent and treat such pathologies, women used a combination of traditional and biomedical therapies, depending on the perceived cause of illness. In general, however, a marked preference for traditional systems of care was observed. CONCLUSION: Health problems related to breastfeeding are perceived to be very common in rural Burkina Faso. Further epidemiological research to assess the actual prevalence of such pathologies is urgently needed to inform the design of adequate control measures, especially given the impact of mastitis on HIV vertical transmission. Our investigation into local illness concepts and health care seeking behaviour is useful to ensure that such measures be culturally sensitive. Further research into the efficacy of local customs and traditional healing methods and their effect on viral load in breast milk is also urgently needed

The Magnitude and Kinetics of the Mucosal HIV-Specific CD8+ T Lymphocyte Response and Virus RNA Load in Breast Milk

BACKGROUND: The risk of postnatal HIV transmission is associated with the magnitude of the milk virus load. While HIV-specific cellular immune responses control systemic virus load and are detectable in milk, the contribution of these responses to the control of virus load in milk is unknown. METHODS: We assessed the magnitude of the immunodominant GagRY11 and subdominant EnvKY9-specific CD8+ T lymphocyte response in blood and milk of 10 A*3002+, HIV-infected Malawian women throughout the period of lactation and correlated this response to milk virus RNA load and markers of breast inflammation. RESULTS: The magnitude and kinetics of the HIV-specific CD8+ T lymphocyte responses were discordant in blood and milk of the right and left breast, indicating independent regulation of these responses in each breast. However, there was no correlation between the magnitude of the HIV-specific CD8+ T lymphocyte response and the milk virus RNA load. Further, there was no correlation between the magnitude of this response and markers of breast inflammation. CONCLUSIONS: The magnitude of the HIV-specific CD8+ T lymphocyte response in milk does not appear to be solely determined by the milk virus RNA load and is likely only one of the factors contributing to maintenance of low virus load in milk

Deletion of Genes Implicated in Protecting the Integrity of Male Germ Cells Has Differential Effects on the Incidence of DNA Breaks and Germ Cell Loss

Infertility affects approximately 20% of couples in Europe and in 50% of cases the problem lies with the male partner. The impact of damaged DNA originating in the male germ line on infertility is poorly understood but may increase miscarriage. Mouse models allow us to investigate how deficiencies in DNA repair/damage response pathways impact on formation and function of male germ cells. We have investigated mice with deletions of ERCC1 (excision repair cross-complementing gene 1), MSH2 (MutS homolog 2, involved in mismatch repair pathway), and p53 (tumour suppressor gene implicated in elimination of germ cells with DNA damage).We demonstrate for the first time that depletion of ERCC1 or p53 from germ cells results in an increased incidence of unrepaired DNA breaks in pachytene spermatocytes and increased numbers of caspase-3 positive (apoptotic) germ cells. Sertoli cell-only tubules were detected in testes from mice lacking expression of ERCC1 or MSH2 but not p53. The number of sperm recovered from epididymes was significantly reduced in mice lacking testicular ERCC1 and 40% of sperm contained DNA breaks whereas the numbers of sperm were not different to controls in adult Msh2 -/- or p53 -/- mice nor did they have significantly compromised DNA.These data have demonstrated that deletion of Ercc1, Msh2 and p53 can have differential but overlapping affects on germ cell function and sperm production. These findings increase our understanding of the ways in which gene mutations can have an impact on male fertility