Effect of Sleep on the Attentiveness of Elemetary School Students

Sleep is known to be important in the development of children and their cognitive functioning. This study worked to establish correlation between amount of sleep and attentiveness in school-aged children. This study surveyed the parents of 10 third graders on their child’s sleep habits. The children were read a story in class and asked to answer questions based on details in the story. The data obtained from this quiz and the parent’s survey responses were then compared to see if there was a relation. The results of this study were inconclusive. When genders were separated, it was found that males slept the most but females got more answers correct on the quiz. However, when the data was organized based on the recommended sleep amount for this age, it was found that children who met the recommendation answered more questions correctly compared to those who did not

Red Lionfish (Pterois volitans) Invade San Salvador, Bahamas: No Early Effects on Coral and Fish Communities

The red lionfish, Pterois volitans, was first reported at San Salvador, Bahamas in January 2006; by 2009 they were common in waters 2 to 40 m deep around the island. Among the 5,078 fish observed on shallow patch reefs in 2007, only two were P. volitans; they were much more prevalent in deeper water along San Salvador’s platform wall. Captured P. volitans ranged in size from 19-32 cm, all longer than maturity length. Pallid goby (Coryphopterus eidolon), blackcap basslet (Gramma melacara) and red night shrimp (Rynchocienetes rigens) were the most commonly identified stomach contents. Our study in 2007 also collected data on coral and fish communities at three, near-shore patch reef complexes (Rice Bay, Rocky Point, Lindsay Reef, and compared the results to a similar study done in 2001, before P. volitans was discovered at San Salvador. Scleractinian and, therefore, total coral species richness decreased significantly from 2001 to 2007; however, coral percentage cover increased significantly by approximately 50% during the same period, probably due to a more precise estimation procedure rather than a real increase. Even after adjustment for CPUE (2.25 more effort in 2007 than in 2001), significantly more fish were observed in 2007 than in 2001. Continued monitoring of lionfish numbers and potentially associated changes in patch reef ecology is recommended

Identifying galaxy candidates in WSRT HI imaging of ultra-compact high velocity clouds

Ultra-compact high velocity clouds (UCHVCs) were identified in the ALFALFA HI survey as potential gas-bearing dark matter halos. Here we present higher resolution neutral hydrogen (HI) observations of twelve UCHVCS with the Westerbork Synthesis Radio Telescope (WSRT). The UCHVCs were selected based on a combination of size, isolation, large recessional velocity and high column density as the best candidate dark matter halos. The WSRT data were tapered to image the UCHVCs at 210" (comparable to Arecibo) and 105" angular resolution. In a comparison of the single-dish to interferometer data, we find that the line flux recovered in the WSRT observations is comparable to that from the single-dish ALFALFA data. In addition, any structure seen in the ALFALFA data is reproduced in the WSRT maps at the same angular resolution. At 210'" resolution all the sources are generally compact with a smooth HI morphology, as expected from their identification as UCHVCs. At the higher angular resolution, a majority of the sources break into small clumps contained in a diffuse envelope. These UCHVCs also have no ordered velocity motion and are most likely Galactic halo clouds. We identify two UCHVCs, AGC 198606 and AGC 249525, as excellent galaxy candidates based on maintaining a smooth HI morphology at higher angular resolution and showing ordered velocity motion consistent with rotation. A third source, AGC 249565, lies between these two populations in properties and is a possible galaxy candidate. If interpreted as gas-bearing dark matter halos, the three candidate galaxies have rotation velocities of 8-15 km/s, HI masses of 0.6-50 x 10^5 Msun, HI radii of 0.3-2 kpc, and dynamical masses of 2-20 x 10^7 Msun for a range of plausible distances. These are the UCHVCs with the highest column density values in the ALFALFA HI data and we suggest this is the best way to identify further candidates.Comment: Accepted for publication in A&A. 26 pages, 19 figures, 5 table

Modeling of intrinsic electron and hole trapping in crystalline and amorphous ZnO

Recent advances in ultrafast liquid quenching and deposition of thin films on cold substrates make growing amorphous (a)‐ZnO films increasingly feasible. The electronic structure and electron and hole trapping properties of amorphous ZnO are predicted using density functional theory (DFT) simulations with a hybrid density functional (h‐DFT). An ensemble of fifty 324‐atom structures is employed to obtain the distribution of structural and electronic properties of a‐ZnO. The results demonstrate that electrons do not localize in a‐ZnO, but holes form deep localized states with average trapping energy of about 0.9 eV. It is also shown that dispersion at the conduction band minimum (CBM) is not affected upon amorphization, suggesting that high electron mobility should be retained. An average value of a‐ZnO band gap of 3.36 eV is calculated with no states splitting into the band gap, which accounts for no substantial detrimental effect on the optical transparency upon amorphization. These findings may have important implications for future applications of a‐ZnO as a transparent conductor and photocatalyst

The complex network of global cargo ship movements

Transportation networks play a crucial role in human mobility, the exchange of goods, and the spread of invasive species. With 90% of world trade carried by sea, the global network of merchant ships provides one of the most important modes of transportation. Here we use information about the itineraries of 16,363 cargo ships during the year 2007 to construct a network of links between ports. We show that the network has several features which set it apart from other transportation networks. In particular, most ships can be classified in three categories: bulk dry carriers, container ships and oil tankers. These three categories do not only differ in the ships' physical characteristics, but also in their mobility patterns and networks. Container ships follow regularly repeating paths whereas bulk dry carriers and oil tankers move less predictably between ports. The network of all ship movements possesses a heavy-tailed distribution for the connectivity of ports and for the loads transported on the links with systematic differences between ship types. The data analyzed in this paper improve current assumptions based on gravity models of ship movements, an important step towards understanding patterns of global trade and bioinvasion.Comment: 7 figures Accepted for publication by Journal of the Royal Society Interface (2010) For supplementary information, see http://www.icbm.de/~blasius/publications.htm

Glass Polymorphism in TIP4P/2005 Water: A Description Based on the Potential Energy Landscape Formalism

The potential energy landscape (PEL) formalism is a statistical mechanical approach to describe supercooled liquids and glasses. Here we use the PEL formalism to study the pressure-induced transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA) using computer simulations of the TIP4P/2005 molecular model of water. We find that the properties of the PEL sampled by the system during the LDA-HDA transformation exhibit anomalous behavior. In particular, at conditions where the change in density during the LDA-HDA transformation is approximately discontinuous, reminiscent of a first-order phase transition, we find that (i) the inherent structure (IS) energy, $e_\text{IS}(V)$, is a concave function of the volume, and (ii) the IS pressure, $P_\text{IS}(V)$, exhibits a van der Waals-like loop. In addition, the curvature of the PEL at the IS is anomalous, a non-monotonic function of $V$. In agreement with previous studies, our work suggests that conditions (i) and (ii) are necessary (but not sufficient) signatures of the PEL for the LDA-HDA transformation to be reminiscent of a first-order phase transition. We also find that one can identify two different regions of the PEL, one associated to LDA and another to HDA. Our computer simulations are performed using a wide range of compression/decompression and cooling rates. In particular, our slowest cooling rate (0.01 K/ns) is within the experimental rates employed in hyperquenching experiments to produce LDA. Interestingly, the LDA-HDA transformation pressure that we obtain at $T=80$ K and at different rates extrapolates remarkably well to the corresponding experimental pressure.Comment: Manuscript and Supplementary Materia