Indirect effects of primary prey population dynamics on alternative prey

We develop a theory of generalist predation showing how alternative prey species are affected by changes in both mean abundance and variability (coefficient of variation) of their predator's primary prey. The theory is motivated by the indirect effects of cyclic rodent populations on ground-breeding birds, and developed through progressive analytic simplifications of an empirically-based model. It applies nonetheless to many other systems where primary prey have fast life-histories and can become locally superabundant, which facilitates impact on alternative prey species. In contrast to classic apparent competition theory based on symmetric interactions, our results suggest that predator effects on alternative prey should generally decrease with mean primary prey abundance, and increase with primary prey variability (low to high CV) - unless predators have strong aggregative responses, in which case these results can be reversed. Approximations of models including predator dynamics (general numerical response with possible delays) confirm these results but further suggest that negative temporal correlation between predator and primary prey is harmful to alternative prey. We find in general that predator numerical responses are crucial to predict the response of ecosystems to changes in key prey species exhibiting outbreaks, and extend the apparent competition/mutualism theory to asymmetric interactions

Angular Momentum Changes Due to Direct Impact Accretion in a Simplified Binary System

We model a circular mass-transferring binary system to calculate the exchange of angular momentum between stellar spins and the orbit due to direct impact of the mass transfer stream onto the surface of the accretor. We simulate mass transfer by calculating the ballistic motion of a point mass ejected from the $L_1$ point of the donor star, conserving the total linear and angular momentum of the system, and treating the stars as uniform density spheres with main sequence radii determined by their masses. We show that, contrary to previous assumptions in the literature, direct impact does not always act as a sink of orbital angular momentum and may in fact increase it by facilitating the transfer of angular momentum from the spin of the donor to the orbit. Here, we show an example of the exchange of angular momentum, as well as a measure of the orbital angular momentum changes for a variety of binary star systems with main sequence components.Comment: 2 pages, 2 figures, Conference Proceedings for the International Conference on Binaries, Mykonos, Greece. Updated Version of Fig. 1b, correcting a scaling error. Results remain unchanged, but the numerical scaling factors have been decrease

Stellar clusters in the inner Galaxy and their correlation with cold dust emission

Stars are born within dense clumps of giant molecular clouds, constituting young stellar agglomerates known as embedded clusters, which only evolve into bound open clusters under special conditions. We statistically study all embedded clusters (ECs) and open clusters (OCs) known so far in the inner Galaxy, investigating particularly their interaction with the surrounding molecular environment and the differences in their evolution. We first compiled a merged list of 3904 clusters from optical and infrared clusters catalogs in the literature, including 75 new (mostly embedded) clusters discovered by us in the GLIMPSE survey. From this list, 695 clusters are within the Galactic range |l| < 60 deg and |b| < 1.5 deg covered by the ATLASGAL survey, which was used to search for correlations with submm dust continuum emission tracing dense molecular gas. We defined an evolutionary sequence of five morphological types: deeply embedded cluster (EC1), partially embedded cluster (EC2), emerging open cluster (OC0), OC still associated with a submm clump in the vicinity (OC1), and OC without correlation with ATLASGAL emission (OC2). Together with this process, we performed a thorough literature survey of these 695 clusters, compiling a considerable number of physical and observational properties in a catalog that is publicly available. We found that an OC defined observationally as OC0, OC1, or OC2 and confirmed as a real cluster is equivalent to the physical concept of OC (a bound exposed cluster) for ages in excess of ~16 Myr. Some observed OCs younger than this limit can actually be unbound associations. We found that our OC and EC samples are roughly complete up to ~1 kpc and ~1.8 kpc from the Sun, respectively, beyond which the completeness decays exponentially. Using available age estimates for a few ECs, we derived an upper limit of 3 Myr for the duration of the embedded phase... (Abridged)Comment: 39 pages, 9 figures. Accepted for publication in A&A on Sept 16, 2013. The catalog will be available at the CDS after official publication of the articl

Analisis Yuridis Tentang Hukum Asuransi Dalam Transaksi Electronic Commerce Melalui Perspektif Kitab Undang-undang Hukum Dagang

Seiring dengan perkembangan teknologi dan informasi di dunia, berbagai hal baru muncul di dalam kehidupan kita sehari-hari. Salah satunya adalah konsep jual beli secara online melalui internet dengan menggunakan e-commerce . Dengan e-commerce konsep jual beli tradisonal yang mempertemukan pembeli dan penjual dalam satu ruangan berubah menjadi konsep jual beli jarak jauh atau telemarketing. Dengan adanya konsep ini, tentu saja baik penjual dan pembeli akan merasa di untungkan, karena transaksi jual beli yang terjadi dapat dilakukan 24 jam penuh dengan tidak dibatasi oleh wilayah tertentu. Akan tetapi selain memberikan keuntungan, tentu saja konsep jual beli jarak jauh melalui e-commerce juga dapat menimbulkan banyak resiko kerugian, salah satunya adalah serangan cyber crime yang dapat menyebabkan penyalahgunaan data para pihak dalam e-commerce sehingga mengalami kerugian. Penelitian dalam Artikel ilmiah ini dilakukan untuk dapat mengetahui dan menganalisis bagaimana Kitab Undang-Undang Hukum Dagang (KUHD) mengatur Asuransi yang berhubungan dengan transaksi elektronik melalui internet (e-commerce), mengetahui dan menganalisis pihak - pihak yang dapat dijadikan subyek dan obyek asuransi dalam transaksi elektronik melalui internet (ecommerce), serta menganalisis penyebab perlunya asuransi dalam transaksi electronic commerce diatur secara khusus di dalam peraturan Perundang-undangan di Indonesia. Metode penelitian yang di pakai dalam penulisan Artikel ilmiah ini adalah metode Penelitian hukum normatif yang bertujuan untuk menemukan landasan hukum yang jelas dalam meletakkan persoalan yang diangkat, dalam perspektif Kitab Undang-Undang Hukum Dagang, khususnya yang terkait dengan masalah penerapan asuransi dalam transaksi e-commerce. Berdasarkan pembahasan terhadap hasil penelitian terungkap bahwa dari pengertian dan batasan tentang asuransi di dalam KUHD, transaksi e-commerce merupakan obyek yang dapat di asuransikan, karena segala kegiatan didalam transaksi e-commerce, dapat menimbulkan kehilangan atau kerusakan bagi para pihak yang ada didalamnya. Pengaturan asuransi mengenai e-commerce di dalam KUHD sebenarnya perlu diatur secara rinci, sehingga pemerintah hendaknya melakukan revisi Undang-Undang Nomor 2 Tahun 1992 tentang Usaha Pengasuransian, sehingga dapat memberikan pengaturan jelas mengenai asuransi dalam transaksi bisnis e-commerce atau cyber insurance

Constitutional Law - Separation of Church and State - Bible Reading in the Public Schools

The plaintiff, as a citizen, taxpayer, and parent of school children, sought an injunction to restrain the defendant school board from allowing school teachers to read the Bible aloud to students as required by a Tennessee statute. The plaintiff contended that this practice was offensive to him and in violation of the Tennessee and United States Constitutions. The trial court sustained defendant\u27s demurrer. On appeal, held, affirmed. The statute violates neither constitution because it is not an interference with students\u27 or parents\u27 religious beliefs. Carden v. Bland, (Tenn. 1956) 288 S. W. (2d) 718

The ideology of media. Measuring the political leaning of Spanish news media through Twitter users’ interactions

The news media have a strong influence on people’s perception of reality. But despite claims to objectivity, media organizations are, in general, politically biased (Patterson & Donsbach, 1996; Gaebler, 2017). The link between news media outlets and political organizations has been a critical question in political science and communication studies. To assess the closeness between the news media and particular political organizations, scholars have used different methods such as content analysis, undertaking surveys or adopting a political economy view. With the advent of social networks, new sources of data are now available to measure the relationship between media organizations and parties. Assuming that users coherently retweet political and news information (Wong, Tan, Sen & Chiang, 2016), and drawing on the retweet overlap network (RON) method (Guerrero-Solé, 2017), this research uses people’s perceived ideology of Spanish political parties (CIS, 2020) to propose a measure of the ideology of news media in Spain. Results show that scores align with the result of previous research on the ideology of the news media (Ceia, 2020). We also find that media outlets are, in general, politically polarized with two groups or clusters of news media being close to the left-wing parties UP and PSOE, and the other to the right-wing and far-right parties Cs, PP, and Vox. This research also underlines the media’s ideological stability over time.Los medios de comunicación tienen una fuerte influencia sobre la percepción de la realidad que tiene la gente. A pesar de su pretensión de objetividad, los medios tienen, en general, un sesgo político (Patterson & Donsbach, 1996; Gaebler, 2017). La relación entre los medios y las organizaciones políticas ha sido una cuestión crucial en los estudios de ciencias políticas y comunicación. Para evaluar la proximidad entre los medios de comunicación y organizaciones políticas concretas, los investigadores han empleado distintos métodos como el análisis de contenido, las encuestas o la adopción de una visión político-económica. Con la llegada de las redes sociales, aparecen nuevas fuentes de datos disponibles para medir la relación entre los medios de comunicación y los partidos políticos. Asumiendo que los usuarios retuitean coherentemente información política y mediática (Wong, Tan, Sen & Chiang, 2016), y haciendo uso del método RON (Retweet Overlap Network) (Guerrero-Solé, 2017), este estudio utiliza la ideología percibida por la población de los partidos políticos españoles (CIS, 2020) para proponer una medida de la ideología de los medios de comunicación en España. Los resultados muestran que las puntuaciones obtenidas siguen la línea de estudios realizados previamente sobre la ideología de los medios (Ceia, 2020). También se ha descubierto que los medios, en general, están polarizados políticamente, con dos grupos de medios más próximos a los partidos de izquierda UP y PSOE, y los otros a los partidos de derecha y ultraderecha Cs, PP y Vox. Esta investigación también remarca la estabilidad ideológica de los medios a lo largo del tiempo

Dynamical Interactions of Planetary Systems in Dense Stellar Environments

We study dynamical interactions of star--planet binaries with other single stars. We derive analytical cross sections for all possible outcomes, and confirm them with numerical scattering experiments. We find that a wide mass ratio in the binary introduces a region in parameter space that is inaccessible to comparable-mass systems, in which the nature of the dynamical interaction is fundamentally different from what has traditionally been considered in the literature on binary scattering. We study the properties of the planetary systems that result from the scattering interactions for all regions of parameter space, paying particular attention to the location of the "hard--soft" boundary. The structure of the parameter space turns out to be significantly richer than a simple statement of the location of the "hard--soft" boundary would imply. We consider the implications of our findings, calculating characteristic lifetimes for planetary systems in dense stellar environments, and applying the results to previous analytical studies, as well as past and future observations. Recognizing that the system PSR B1620-26 in the globular cluster M4 lies in the "new" region of parameter space, we perform a detailed analysis quantifying the likelihood of different scenarios in forming the system we see today.Comment: Accepted for publication in ApJ. Minor changes to reflect accepted version. 14 pages, 14 figure