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Search Results: 1 - 10 of 153 matches for " Kristan Aronson "
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Stress and breast cancer: from epidemiology to molecular biology
Lilia Antonova, Kristan Aronson, Christopher R Mueller
Breast Cancer Research , 2011, DOI: 10.1186/bcr2836
Abstract: Studies have estimated that approximately 50% of breast cancer incidence can be attributed to known genetic, physiologic, or behavioral risk factors [1], with genetic risk factors accounting for 5 to 10% of breast cancer cases [2]. Established physiological and behavioral risk factors for breast cancer include having a first-degree relative with breast cancer, early menarche, late menopause, nulliparity or bearing of first child at a later age, overweight after menopause, certain types of benign breast diseases, alcohol consumption, and long-term use of menopausal estrogen replacement therapy [3]. In addition to these well-characterized contributors, other factors, whose effects have been more difficult to evaluate, are suspected of conferring increased breast cancer risk. These factors include smoking, certain aspects of nutrition (meat and fat consumption), physical activity, and psychological stress [4,5].The possible contribution of psychological stress to breast cancer development has been extensively studied. Literature on the topic is not only abundant, spanning several decades, but is scattered between the fields of epidemiology, physiology, and molecular biology. Whereas the largest amount of literature focuses on using epidemiologic methods to look for a connection between exposure to stress and subsequent breast cancer diagnosis, this portion of the literature is also the most difficult to assess. Studies in this area differ greatly in their findings, probably due to differences in factors such as study design, the effects of confounding, type of stress exposure, and timing of stress exposure or stress exposure measurement. On the other hand, animal literature on the topic is simpler to interpret, for the most part pointing to a connection between physiological stress signaling and breast cancer development. This literature is limited, however, by a lack of variability in stress exposure parameters and the differences in breast physiology and development
Estrogen and progesterone receptor levels in nonneoplastic breast epithelium of breast cancer cases versus benign breast biopsy controls
Christy G Woolcott, Sandip K SenGupta, Wedad M Hanna, Kristan J Aronson
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-130
Abstract: Between 1995 and 1997 at two sites (Women's College Hospital in Toronto and Kingston General Hospital), 667 women who were scheduled for diagnostic excisional breast biopsies completed a questionnaire providing personal information and agreed to allow analysis of routinely resected tissue. Histological slides with nonneoplastic epithelium were available for 101 cancer cases and 200 biopsy controls in Toronto and for 105 cancer cases and 119 controls in Kingston. Nonneoplastic epithelium was examined with immunohistochemical assays to determine the percent of epithelial cells staining for ER and PR. Unconditional logistic regression was used to calculate odds ratios (OR) stratified by study site.The ER content of nonneoplastic tissue was higher in cases than biopsy controls in unadjusted analyses; after adjustment for age, however, a weak association remained in only one of the study sites. After adjustment for age, the PR content of nonneoplastic tissue was slightly lower in breast cancer cases than controls in one study site. Furthermore, this inverse association was confined to women with PR negative breast cancer in comparison to the controls. No interaction between ER and PR content of nonneoplastic tissue was observed in relation to the odds of having breast cancer.The results of this study are consistent with only a slight indication of increased ER levels in nonneoplastic tissue in breast cancer cases relative to controls. This study contributes to the understanding of breast cancer by examining both ER and PR in nonneoplastic tissue. Limitations remain, however, such as the necessity of using as controls women with benign breast changes, difficulties in selecting the appropriate tissue for analysis, and tissue sampling concurrent to diagnosis.Breast cancer risk factors such as early age at menarche, late age at menopause, postmenopausal hormone therapy, and high body mass index are thought to affect breast carcinogenesis by increasing the exposure of the bre
Folate intake, alcohol consumption, and the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism: influence on prostate cancer risk and interactions
Lindsay C. Kobayashi,Qun Miao,Thomas E. Massey,Kristan J. Aronson
Frontiers in Oncology , 2012, DOI: 10.3389/fonc.2012.00100
Abstract: Purpose: Folate is essential to DNA methylation and synthesis and may have a complex dualistic role in prostate cancer. Alcohol use may increase risk and epigenetic factors may interact with lifestyle exposures. We aimed to characterize the independent and joint effects of folate intake, alcohol consumption, and the MTHFR C677T gene polymorphism on prostate cancer risk, while accounting for intakes of vitamins B2, B6, B12, methionine, total energy, and confounders. Methods: A case-control study was conducted at Kingston General Hospital of 80 incident primary prostate cancer cases and 334 urology clinic controls, all with normal age-specific PSA levels (to exclude latent prostate cancers). Participants completed a questionnaire on folate and alcohol intakes and potential confounders prior to knowledge of diagnosis, eliminating recall bias, and blood was drawn for MTHFR genotyping. Joint effects of exposures were assessed using unconditional logistic regression and significance of multiplicative and additive interactions using general linear models. Results: Folate, vitamins B2, B6, B12, methionine, and the CT and TT genotypes were not associated with prostate cancer risk. The highest tertile of lifetime alcohol consumption was associated with increased risk (OR = 2.08; 95% CI: 1.12–3.86). Consumption of >5 alcoholic drinks per week was associated with increased prostate cancer risk among men with low folate intake (OR = 2.38; 95% CI: 1.01–5.57), and higher risk among those with the CC MTHFR genotype (OR = 4.43; 95% CI: 1.15–17.05). Increased risk was also apparent for average weekly alcohol consumption when accounting for the multiplicative interaction between folate intake and MTHFR C677T genotype (OR = 3.22; 95% CI: 1.36–7.59). Conclusion: Alcohol consumption is associated with increased prostate cancer risk, and this association is stronger among men with low folate intake, with the CC MTHFR genotype, and when accounting for the joint effect of folate intake and MTHFR C677T genotype.
Pre-school reading badge called "Iridescent Little Fish" and its impact on reading habits later in life
Slavka Kristan
Knji?nica : Revija za Podro?je Bibliotekarstva in Informacijske Znanosti , 1997,
Abstract: The project called Footsteps to the Book is being carried out at the youth department of the Library Miran Jarc in Novo mesto; in it, preschool children from the municipalities Novo mesto, entjernej and kocjan participate. The child wins the reading badge - Iridescent Little Fish with a pin - by telling four stories (or poems)in the library that havebeen told or read to him by his parents. Family appreciation can be won by both parents and children. The project has been started with the intention of lessening the impact of media upon children, and of strengthening the spiritual bondage among parents and children through reading. The purpose of the above mentioned activity is to develop and enrich child's language and thinking and help h im form positive self esteem. Through family reading, we tried to attract to the library not only small children but also their parents and to get them accustomed to the regular use of library materials. The opinions of parents,librarians, teachers and educators are very encouraging and the cooperation of children is better each year.
Semi-Holographic Quantum Criticality
Kristan Jensen
Physics , 2011, DOI: 10.1103/PhysRevLett.107.231601
Abstract: We identify the near-critical effective theory (EFT) for a wide class of low-temperature phase transitions found via holography. The EFT is of the semi-holographic type and describes both holographic Berezinskii-Kosterlitz-Thouless (BKT) and second-order transitions with non-trivial scaling. It is a simple generalization of the Ginzburg-Landau-Wilson paradigm to systems with an emergent (or hidden) conformal sector. Having identified the near-critical EFT, we explore its basic phenomenology by computing critical exponents and low-frequency correlators.
Lower bounds to the spectral gap of Davies generators
Kristan Temme
Physics , 2013, DOI: 10.1063/1.4850896
Abstract: We construct lower bounds to the spectral gap of a family of Lindblad generators known as Davies maps. These maps describe the thermalization of quantum systems weakly coupled to a heat bath. The steady state of these systems is given by the Gibbs distribution with respect to the system Hamiltonian. The bounds can be evaluated explicitly, when the eigenbasis and the spectrum of the Hamiltonian is known. A crucial assumption is that the spectrum of the Hamiltonian is non-degenerate. Furthermore, we provide a counterexample to the conjecture, that the convergence rate is always determined by the gap of the associated Pauli master equation. We conclude, that the full dynamics of the Lindblad generator has to be considered. Finally, we present several physical example systems for which the bound to the spectral gap is evaluated.
Thermalization time bounds for Pauli stabilizer Hamiltonians
Kristan Temme
Physics , 2014,
Abstract: We prove a general lower bound to the spectral gap of the Davies generator for Pauli stabilizer Hamiltonians. These Hamiltonians, defined on the Hilbert space of $N$-qubits, serve as one of the most frequently considered candidates for a self-correcting quantum memory. A spectral gap bound on the Davies generator establishes an upper limit on the life time of such a quantum memory and can be used to estimate the time until the system relaxes to thermal equilibrium when brought into contact with a thermal heat bath. The bound can be shown to behave as $\lambda \geq {\cal O}(N^{-1}\exp(-2\beta \, \overline{\epsilon}))$, where $\overline{\epsilon}$ is a generalization of the well known energy barrier for logical operators. Particularly in the low temperature regime we expect this bound to provide the correct asymptotic scaling of the gap with the system size up to a factor of $N^{-1}$.
More Holographic Berezinskii-Kosterlitz-Thouless Transitions
Kristan Jensen
Physics , 2010, DOI: 10.1103/PhysRevD.82.046005
Abstract: We find two systems via holography that exhibit quantum Berezinskii-Kosterlitz-Thouless (BKT) phase transitions. The first is the ABJM theory with flavor and the second is a flavored (1,1) little string theory. In each case the transition occurs at nonzero density and magnetic field. The BKT transition in the little string theory is the first example of a quantum BKT transition in (3+1) dimensions. As in the "original" holographic BKT transition in the D3/D5 system, the exponential scaling is destroyed at any nonzero temperature and the transition becomes second order. Along the way we construct holographic renormalization for probe branes in the ABJM theory and propose a scheme for the little string theory. Finally, we obtain the embeddings and (half of) the meson spectrum in the ABJM theory with massive flavor.
Chiral anomalies and AdS/CMT in two dimensions
Kristan Jensen
Physics , 2010, DOI: 10.1007/JHEP01(2011)109
Abstract: I clarify some recent confusion regarding the holographic description of finite-density systems in two dimensions. Notably, the chiral anomaly for symmetry currents in 2d conformal field theories (CFT) completely determines their correlators. The important exception is a CFT with a gauge theory to which we may couple an external current, as in the probe D3/D3 system or the putative dual to the charged BTZ black hole. These systems are analyzed with an eye for potential condensed matter applications.
On the coupling of Galilean-invariant field theories to curved spacetime
Kristan Jensen
Physics , 2014,
Abstract: We consider the problem of coupling Galilean-invariant quantum field theories to a fixed spacetime. We propose that to do so, one couples to Newton-Cartan geometry and in addition imposes a one-form shift symmetry. This additional symmetry imposes invariance under Galilean boosts, and its Ward identity equates particle number and momentum currents. We show that Newton-Cartan geometry subject to the shift symmetry arises in null reductions of Lorentzian manifolds, and so our proposal is realized for theories which are holographically dual to quantum gravity on Schr\"odinger spacetimes. We use this null reduction to efficiently form tensorial invariants under the boost and particle number symmetries. We also explore the coupling of Schr\"odinger-invariant field theories to spacetime, which we argue necessitates the Newton-Cartan analogue of Weyl invariance.
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