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

Spectrum of gluten-related disorders: consensus on new nomenclature and classification

A decade ago celiac disease was considered extremely rare outside Europe and, therefore, was almost completely ignored by health care professionals. In only 10 years, key milestones have moved celiac disease from obscurity into the popular spotlight worldwide. Now we are observing another interesting phenomenon that is generating great confusion among health care professionals. The number of individuals embracing a gluten-free diet (GFD) appears much higher than the projected number of celiac disease patients, fueling a global market of gluten-free products approaching $2.5 billion (US) in global sales in 2010. This trend is supported by the notion that, along with celiac disease, other conditions related to the ingestion of gluten have emerged as health care concerns. This review will summarize our current knowledge about the three main forms of gluten reactions: allergic (wheat allergy), autoimmune (celiac disease, dermatitis herpetiformis and gluten ataxia) and possibly immune-mediated (gluten sensitivity), and also outline pathogenic, clinical and epidemiological differences and propose new nomenclature and classifications

Dynamic Phenotypic Clustering in Noisy Ecosystems

In natural ecosystems, hundreds of species typically share the same environment and are connected by a dense network of interactions such as predation or competition for resources. Much is known about how fixed ecological niches can determine species abundances in such systems, but far less attention has been paid to patterns of abundances in randomly varying environments. Here, we study this question in a simple model of competition between many species in a patchy ecosystem with randomly fluctuating environmental conditions. Paradoxically, we find that introducing noise can actually induce ordered patterns of abundance-fluctuations, leading to a distinct periodic variation in the correlations between species as a function of the phenotypic distance between them; here, difference in growth rate. This is further accompanied by the formation of discrete, dynamic clusters of abundant species along this otherwise continuous phenotypic axis. These ordered patterns depend on the collective behavior of many species; they disappear when only individual or pairs of species are considered in isolation. We show that they arise from a balance between the tendency of shared environmental noise to synchronize species abundances and the tendency for competition among species to make them fluctuate out of step. Our results demonstrate that in highly interconnected ecosystems, noise can act as an ordering force, dynamically generating ecological patterns even in environments lacking explicit niches

Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles

Release of membrane vesicles, a process conserved in both prokaryotes and eukaryotes, represents an evolutionary link, and suggests essential functions of a dynamic extracellular vesicular compartment (including exosomes, microparticles or microvesicles and apoptotic bodies). Compelling evidence supports the significance of this compartment in a broad range of physiological and pathological processes. However, classification of membrane vesicles, protocols of their isolation and detection, molecular details of vesicular release, clearance and biological functions are still under intense investigation. Here, we give a comprehensive overview of extracellular vesicles. After discussing the technical pitfalls and potential artifacts of the rapidly emerging field, we compare results from meta-analyses of published proteomic studies on membrane vesicles. We also summarize clinical implications of membrane vesicles. Lessons from this compartment challenge current paradigms concerning the mechanisms of intercellular communication and immune regulation. Furthermore, its clinical implementation may open new perspectives in translational medicine both in diagnostics and therapy

Bayes procedures for adaptive inference in nonparametric inverse problems

We study empirical and hierarchical Bayes approaches to the problem of estimating an infinite-dimensional parameter in mildly ill-posed inverse problems. We consider a class of prior distributions indexed by a hyperparameter that quantifies regularity. We prove that both methods we consider succeed in automatically selecting this parameter optimally, resulting in optimal convergence rates for truths with Sobolev or analytic smoothness , without using knowledge about this regularity. Both methods are illustrated by simulation examples

Empirical Bayes scaling of Gaussian priors in the white noise model

The performance of nonparametric estimators is heavily dependent on a bandwidth parameter. In nonparametric Bayesian methods this parameter can be specified as a hyperparameter of the nonparametric prior. The value of this hyperparameter may be made dependent on the data. The empirical Bayes method is to set its value by maximizing the marginal likelihood of the data in the Bayesian framework. In this paper we analyze a particular version of this method, common in practice, that the hyperparameter scales the prior variance. We characterize the behavior of the random hyperparameter, and show that a nonparametric Bayes method using it gives optimal recovery over a scale of regularity classes. This scale is limited, however, by the regularity of the unscaled prior. While a prior can be scaled up to make it appropriate for arbitrarily rough truths, scaling cannot increase the nominal smoothness by much. Surprisingy the standard empirical Bayes method is even more limited in this respect than an oracle, deterministic scaling method. The same can be said for the hierarchical Bayes method

PENELUSURAN INFORMASI BAHAN PUSTAKA MELALUI ONLINE PUBLIC ACCESS CATALOGUE (OPAC) DI AMIKOM RESOURCE CENTER

Penulisan Tugas Akhir ini bertujuan untuk mengetahui cara melakukan penelusuran informasi bahan pustaka melalui OPAC, untuk mengetahui kelebihan dan kekurangan OPAC sebagai sarana penelusuran informasi bahan pustaka, untuk mengetahui hambatan yang dihadapi dalam melakukan penelusuran informasi bahan pustaka melalui OPAC, untuk mengetahui solusi / upaya yang dilakukan untuk mengatasi kendala yang dihadapi dalam penelusuran informasi bahan pustaka melalui OPAC di Amikom Resource Center. Penelitian Tugas Akhir ini dilakukan di Amikom Resource Center, STMIK AMIKOM YOGYAKARTA dengan menggunakan empat metode pengumpulan data yakni metode observasi, metode wawancara, metode dokumentasi, serta metode studi pustaka. Tugas Akhir ini menitikberatkan pada penelusuran informasi bahan pustaka di Amikom Resource Center. Amikom Resource Center menggunakan OPAC berbasis Web dan memanfaatkan menu pencarian pada software Smart Library sebagai sarana penelusurannya. Kesimpulannya antara lain: 1) Langkahlangkah dalam melakukan penelusuran informasi melalui kedua OPAC hampir sama, langkah awal pemustaka dapat mengakses melalui situs website sedangkan untuk pustakawan dan staf dapat mengakses melalui menu pencarian pada software Smart Library, langkah selanjutnya pilih katagori yang telah tersedia, tentukan kata kunci dan lakukan pencarian. 2) Adapun kelebihan dan kekurangan dari kedua sarana penelusuran bahan pustaka tersebut, khususnya terletak pada akses, hak akses, tampilan OPAC, keakuratan hasil informasi yang dihasikan, detail informasi bahan pustaka dari hasil pencarian, download(unduh) detail informasi bahan pustaka. 3) Hambatan yang dihadapi dalam melakukan penelusuran informasi melalui OPAC di Amikom Resource Center, diantaranya : 1) Masalah jaringan, 2) Masalah ketepatan kata kunci / keyword, 3) Pemustaka yang kurang terampil, 4) Masalah kesesuaian data informasi yang dihasilkan, 5) Kelengkapan Informasi Bahan Pustaka / Bibiliografi. Supaya penelusuran informasi bahan pustaka di Amikom Resource Center menjadi lebih baik, maka perlu dilakukan beberapa hal, penyempurnaan teknik penelusuran, menyelenggarakan pendidikan pemakai atau program literasi, penyempurnaan sistem terkomputerisasi dan penambahan staf baru, serta melengkapi informasi bibliografi. Kata Kunci : Penelusuran informasi, Bahan Pustaka, Online Public Access Catalogue (OPAC