Transit Timing and Duration Variations for the Discovery and Characterization of Exoplanets

Transiting exoplanets in multi-planet systems have non-Keplerian orbits which can cause the times and durations of transits to vary. The theory and observations of transit timing variations (TTV) and transit duration variations (TDV) are reviewed. Since the last review, the Kepler spacecraft has detected several hundred perturbed planets. In a few cases, these data have been used to discover additional planets, similar to the historical discovery of Neptune in our own Solar System. However, the more impactful aspect of TTV and TDV studies has been characterization of planetary systems in which multiple planets transit. After addressing the equations of motion and parameter scalings, the main dynamical mechanisms for TTV and TDV are described, with citations to the observational literature for real examples. We describe parameter constraints, particularly the origin of the mass/eccentricity degeneracy and how it is overcome by the high-frequency component of the signal. On the observational side, derivation of timing precision and introduction to the timing diagram are given. Science results are reviewed, with an emphasis on mass measurements of transiting sub-Neptunes and super-Earths, from which bulk compositions may be inferred.Comment: Revised version. Invited review submitted to 'Handbook of Exoplanets,' Exoplanet Discovery Methods section, Springer Reference Works, Juan Antonio Belmonte and Hans Deeg, Eds. TeX and figures may be found at https://github.com/ericagol/TTV_revie

Phenotypic Variation and Bistable Switching in Bacteria

Microbial research generally focuses on clonal populations. However, bacterial cells with identical genotypes frequently display different phenotypes under identical conditions. This microbial cell individuality is receiving increasing attention in the literature because of its impact on cellular differentiation, survival under selective conditions, and the interaction of pathogens with their hosts. It is becoming clear that stochasticity in gene expression in conjunction with the architecture of the gene network that underlies the cellular processes can generate phenotypic variation. An important regulatory mechanism is the so-called positive feedback, in which a system reinforces its own response, for instance by stimulating the production of an activator. Bistability is an interesting and relevant phenomenon, in which two distinct subpopulations of cells showing discrete levels of gene expression coexist in a single culture. In this chapter, we address techniques and approaches used to establish phenotypic variation, and relate three well-characterized examples of bistability to the molecular mechanisms that govern these processes, with a focus on positive feedback.

Using Ontario's "Telehealth" health telephone helpline as an early-warning system: a study protocol

BACKGROUND: The science of syndromic surveillance is still very much in its infancy. While a number of syndromic surveillance systems are being evaluated in the US, very few have had success thus far in predicting an infectious disease event. Furthermore, to date, the majority of syndromic surveillance systems have been based primarily in emergency department settings, with varying levels of enhancement from other data sources. While research has been done on the value of telephone helplines on health care use and patient satisfaction, very few projects have looked at using a telephone helpline as a source of data for syndromic surveillance, and none have been attempted in Canada. The notable exception to this statement has been in the UK where research using the national NHS Direct system as a syndromic surveillance tool has been conducted. METHODS/DESIGN: The purpose of our proposed study is to evaluate the effectiveness of Ontario's telephone nursing helpline system as a real-time syndromic surveillance system, and how its implementation, if successful, would have an impact on outbreak event detection in Ontario. Using data collected retrospectively, all "reasons for call" and assigned algorithms will be linked to a syndrome category. Using different analytic methods, normal thresholds for the different syndromes will be ascertained. This will allow for the evaluation of the system's sensitivity, specificity and positive predictive value. The next step will include the prospective monitoring of syndromic activity, both temporally and spatially. DISCUSSION: As this is a study protocol, there are currently no results to report. However, this study has been granted ethical approval, and is now being implemented. It is our hope that this syndromic surveillance system will display high sensitivity and specificity in detecting true outbreaks within Ontario, before they are detected by conventional surveillance systems. Future results will be published in peer-reviewed journals so as to contribute to the growing body of evidence on syndromic surveillance, while also providing an non US-centric perspective

Treatment of diaphyseal non-unions of the ulna and radius

Non-unions of the forearm often cause severe dysfunction of the forearm as they affect the interosseus membrane, elbow and wrist. Treatment of these non-unions can be challenging due to poor bone stock, broken hardware, scarring and stiffness due to long-term immobilisation. We retrospectively reviewed a large cohort of forearm non-unions treated by using a uniform surgical approach during a period of 33 years (1975-2008) in a single trauma centre. All non-unions were managed following the AO-principles of compression plate fixation and autologous bone grafting if needed. The study cohort consisted of 47 patients with 51 non-unions of the radius and/or ulna. The initial injury was a fracture of the diaphyseal radius and ulna in 22 patients, an isolated fracture of the diaphyseal ulna in 13, an isolated fracture of the diaphyseal radius in 5, a Monteggia fracture in 5, and a Galeazzi fracture-dislocation of the forearm in 2 patients. Index surgery for non-union consisted of open reduction and plate fixation in combination with a graft in 30 cases (59%), open reduction and plate fixation alone in 14 cases (27%), and only a graft in 7 cases (14%). The functional result was assessed in accordance to the system used by Anderson and colleagues. Average follow-up time was 75 months (range 12-315 months). All non-unions healed within a median of 7 months. According to the system of Anderson and colleagues, 29 patients (62%) had an excellent result, 8 (17%) had a satisfactory result, and 10 (21%) had an unsatisfactory result. Complications were seen in six patients (13%). Our results show that treatment of diaphyseal forearm non-unions using classic techniques of compression plating osteosynthesis and autologous bone grafting if needed will lead to a high union rate (100% in our series). Despite clinical and radiographic bone healing, however, a substantial subset of patients will have a less than optimal functional outcom

Combination of RGD Compound and Low-Dose Paclitaxel Induces Apoptosis in Human Glioblastoma Cells

) peptide, to human glioblastoma U87MG cells with combination of low dose Paclitaxel (PTX) pre-treatment to augment therapeutic activity for RGD peptide-induced apoptosis. peptide induced U87MG programmed cell death. The increased expression of PTX-induced integrin-αvβ3 was correlated with the enhanced apoptosis in U87MG cells.This study provides a novel concept of targeting integrin-αvβ3 with RGD peptides in combination with low-dose PTX pre-treatment to improve efficiency in human glioblastoma treatment

Effects of circadian disruption on physiology and pathology: from bench to clinic (and back)

Nested within the hypothalamus, the suprachiasmatic nuclei (SCN) represent a central biological clock that regulates daily and circadian (i.e., close to 24 h) rhythms in mammals. Besides the SCN, a number of peripheral oscillators throughout the body control local rhythms and are usually kept in pace by the central clock. In order to represent an adaptive value, circadian rhythms must be entrained by environmental signals or zeitgebers, the main one being the daily light?dark (LD) cycle. The SCN adopt a stable phase relationship with the LD cycle that, when challenged, results in abrupt or chronic changes in overt rhythms and, in turn, in physiological, behavioral, and metabolic variables. Changes in entrainment, both acute and chronic, may have severe consequences in human performance and pathological outcome. Indeed, animal models of desynchronization have become a useful tool to understand such changes and to evaluate potential treatments in human subjects. Here we review a number of alterations in circadian entrainment, including jet lag, social jet lag (i.e., desynchronization between body rhythms and normal time schedules), shift work, and exposure to nocturnal light, both in human subjects and in laboratory animals. Finally, we focus on the health consequences related to circadian/entrainment disorders and propose a number of approaches for the management of circadian desynchronization.Fil: Chiesa, Juan José. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Duhart, José Manuel. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casiraghi, Leandro Pablo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paladino, Natalia. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bussi, Ivana Leda. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Golombek, Diego Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Radiocarbon re-dating of contact-era Iroquoian history in northeastern North America

A time frame for late Iroquoian prehistory is firmly established on the basis of the presence/absence of European trade goods and other archeological indicators. However, independent dating evidence is lacking. We use 86 radiocarbon measurements to test and (re)define existing chronological understanding. Warminster, often associated with Cahiagué visited by S. de Champlain in 1615–1616 CE, yields a compatible radiocarbon-based age. However, a well-known late prehistoric site sequence in southern Ontario, Draper-Spang-Mantle, usually dated ~1450–1550, yields much later radiocarbon-based dates of ~1530–1615. The revised time frame dramatically rewrites 16th-century contact-era history in this region. Key processes of violent conflict, community coalescence, and the introduction of European goods all happened much later and more rapidly than previously assumed. Our results suggest the need to reconsider current understandings of contact-era dynamics across northeastern North America