Search for α\alpha decay of 151^{151}Eu to the first excited level of 147^{147}Pm using underground γ\gamma-ray spectrometry

The alpha decay of $^{151}$Eu to the first excited level of $^{147}$Pm ($J^\pi = 5/2^+$, $E_{exc}=91.1$ keV) was searched for at the HADES underground laboratory ($\approx 500$ m w.e.). A sample of high purity europium oxide with mass of 303 g and a natural isotopic composition has been measured over 2232.8 h with a high energy resolution ultra-low background n-type semi-planar HPGe detector (40 cm$^3$) with sub-micron deadlayer. The new improved half-life limit has been set as $T_{1/2} \geq 3.7\times 10^{18}$ yr at 68% C.L. Possibilities to improve the sensitivity of the experiment, which is already near the theoretical predictions, are discussed. New half-life limit for $\alpha$ decay of $^{153}$Eu is also set as $T_{1/2} \geq 5.5\times 10^{17}$ yr.Comment: 11 pages, 5 figures, 2 tables, 18 reference

Students’ Models of Magnetic Interactions: A Comparative Analysis of Accurate and Inaccurate Models over a Ten-Year Interval

This research investigates the Models of eighth-grade students in Turkey pertaining to magnets and magnetic interactions, while also examining the consistency of these models within themselves. Additionally, a comparative assessment is conducted by comparing the current data with data collected from eighth-grade students a decade earlier. The study comprises 59 students in the first phase and 45 students in the second phase, all of whom briefly received formal instruction on magnetism during fourth grade. The focus of the analysis centers on identifying the students’ Models and evaluating their coherence across diverse contexts in both phases. Surprisingly, despite the passage of ten years, the mental model patterns exhibited by the students in both studies remain remarkably similar. Three primary categories emerged from the students’ Models of magnets, including attraction and repulsion, magnetic poles, and the composition and functionality of magnets. However, noticeable distinctions between the two studies are evident. In the earlier study, the students’ responses to survey questions displayed a greater variety and detail in comparison to the responses from the later study. Moreover, the second study revealed fewer instances of inconsistent Models concerning the magnetic interaction between magnets and nails, but more instances of inaccurate Models compared to the first study. The findings of this investigation offer valuable insights to educators, guiding them in designing effective lessons and activities aimed at helping students overcome their inaccurate and inconsistent Models

On the performance of West's bubble test: A simulation approach

Cataloged from PDF version of article.In this research we examine the ability of West’s bubble test [1] in detecting speculative bubbles using Brock’s (1982) [2] intertemporal general equilibrium model of asset pricing as the basis for a simulation study. In this setting, (1) the economy, by construction is effi- cient and produces the maximally possible amount of welfare for society, and (2) asset prices reflect the utility-maximizing behavior of consumers and the profit-maximizing behavior of firms. We find that the West’s bubble test flag as ‘‘bubbles” in the simulated data yet the data is produced from an economy in which markets are efficient in welfare production

Genetic characterization and relatedness among autochthonous grapevine cultivars from Northeast Turkey by Simple Sequence Repeats (SSR)

25 autochthonous grapevine cultivars from Northeast Anatolia in Turkey together with two well-known standard cultivars, Cabernet Sauvignon and Merlot were fi ngerprinted using six pairs of SSR primers to assess their genetic diversity and relatedness. All six SSR primers produced successful amplifi cations and revealed DNA polymorphisms that were subsequently used to assess genetic relatedness of the cultivars. A total of 52 alleles were detected with a mean value of 8.67 alleles per locus indicating allele richness. The average expected heterozygosity (He) and observed heterozygosity (Ho) were 0.759 and 0.809, respectively. Considering the number of alleles generated, the highest number was observed in VVS2 loci (14 alleles/locus), while the lowest in VrZAG83 loci (5 alleles/locus). The Unweighted Pair-Group Method with Arithmetic mean (UPGMA) dendrogram constructed based on the SSR data yielded two main clusters. First cluster included only cv. Kibris and the second cluster included rest of the cultivars including Cabernet Sauvignon and Merlot. The results showed that SSR markers have proved to be an effi cient tool for fi ngerprinting grapevine cultivars and conducting genetic diversity studies in grapevine

A Survey About Nothing: Monitoring a Million Supergiants for Failed Supernovae

Extragalactic transient searches have historically been limited to looking for the appearance of new sources such as supernovae. It is now possible to carry out a new kind of survey that will do the opposite, that is, search for the disappearance of massive stars. This will entail the systematic observation of galaxies within a distance of 10 Mpc in order to watch ~10^6 supergiants. Reaching this critical number ensures that something will occur yearly, since these massive stars must end their lives with a core collapse within ~10^6 years. Using deep imaging and image subtraction it is possible to determine the fates of these stars whether they end with a bang (supernova) or a whimper (fall out of sight). Such a survey would place completely new limits on the total rate of all core collapses, which is critical for determining the validity of supernova models. It would also determine the properties of supernova progenitors, better characterize poorly understood optical transients, such as eta Carina-like mass ejections, find and characterize large numbers of Cepheids, luminous blue variables and eclipsing binaries, and allow the discovery of any new phenomena that inhabit this relatively unexplored parameter space.Comment: final version, 7 pages, 5 figures, ApJ in pres

Economic analysis of organic greenhouse lettuce production in Turkey.

Health issues and environmental concerns have drawn the attention to organic agriculture aiming to protect the natural balance and to produce without damaging the environment. This study aims determining economic feasibility of organic greenhouse lettuce (Lactuca sativa L.) in an on farm trial, to foster organic greenhouse vegetable production in the preservation area of Tahtali Dam, projected as the sole water resource of Izmir,Turkey’s third largest. A 384 m2 greenhouse, constructed of galvanized metal tubing anchored and covered with a polyethylene was analyzed to identify typical operation procedures,and to determine unitary construction and operation cost. Organic lettuces were produced during autumn season of 2001-2002, testing different organic fertilizer applications, including two rates of farmyard and poultry manure (30 and 50 t ha-1) with and without two organic fertilizers based on either bacteria or algae. Economical analysis was performed according to different organic fertilizer applications. Cost, yield, and price data were analyzed to determine the profitability of a typical operation. Net return obtained from organic lettuce growing ranged between us $0.376 and us$ 0.901 m-2, as a result of different fertilizer applications