Superconductivity of lanthanum revisited: enhanced critical temperature in the clean limit

The thickness dependence of the superconducting energy gap $\Delta_{\rm{La}}$ of double hexagonally close packed (dhcp) lanthanum islands grown on W(110) is studied by scanning tunneling spectroscopy, from the bulk to the thin film limit. Superconductivity is suppressed by the boundary conditions for the superconducting wavefunction at the surface and W/La interface, leading to a linear decrease of the critical temperature $T_c$ as a function of the inverse film thickness. For thick, bulk-like films, $\Delta_{\rm{La}}$ and $T_c$ are 40% larger as compared to literature values of dhcp La measured by other techniques. This finding is reconciled by examining the effects of surface contamination as probed by modifications of the surface state, suggesting that the large $T_c$ originates in the superior purity of the samples investigated here.Comment: 14 pages, 7 figure

Purple Loosestrife: History, Management, and Biological Control in Iowa

Purple loosestrife (Lythrum salicaria) is an invasive plant species infesting wetlands in North America. Biodiversity and wetland habitat quality are reduced following purple loosestrife establishment. Several management tactics, including cultural, mechanical, and chemical controls, have had limited success in reducing the spread of purple loosestrife. Beginning in the 1990s, a biological control program has introduced several species of natural enemies from Europe that feed on purple loosestrife. Since 1994, Iowa State University has reared and released two species of beetles that feed on purple loosestrife, Galerucella calmariensis and G. pusilla. Biological control is one component of an integrated purple loosestrife management and education program that is needed to reduce the spread and densities of purple loosestrife

Semantic Sentiment Analysis of Twitter Data

Internet and the proliferation of smart mobile devices have changed the way information is created, shared, and spreads, e.g., microblogs such as Twitter, weblogs such as LiveJournal, social networks such as Facebook, and instant messengers such as Skype and WhatsApp are now commonly used to share thoughts and opinions about anything in the surrounding world. This has resulted in the proliferation of social media content, thus creating new opportunities to study public opinion at a scale that was never possible before. Naturally, this abundance of data has quickly attracted business and research interest from various fields including marketing, political science, and social studies, among many others, which are interested in questions like these: Do people like the new Apple Watch? Do Americans support ObamaCare? How do Scottish feel about the Brexit? Answering these questions requires studying the sentiment of opinions people express in social media, which has given rise to the fast growth of the field of sentiment analysis in social media, with Twitter being especially popular for research due to its scale, representativeness, variety of topics discussed, as well as ease of public access to its messages. Here we present an overview of work on sentiment analysis on Twitter.Comment: Microblog sentiment analysis; Twitter opinion mining; In the Encyclopedia on Social Network Analysis and Mining (ESNAM), Second edition. 201

Reply to \u27Do oceanic zooplankton aggregate at, or near, the deep chlorophyll maximum?\u27

We appreciate the time and attention given our paper by Longhurst and Herman and the opportunity to reply to their critique. Unfortunately, we believe their difficulties with the presentation of our data are more subjective than substantive. In fact, we believe a careful reading of our text will show that our conclusions are suitably conservative...

Study of the ground state properties of LiHoxY1−xF4LiHo_xY_{1-x}F_4 using μ\muSR

$LiHo_xY_{1-x}F_4$ is an insulating system where the magnetic Ho$^{3+}$ ions have an Ising character, and interact mainly through magnetic dipolar fields. We used the muon spin relaxation technique to study the nature of the ground state for samples with x=0.25, 0.12, 0.08, 0.045 and 0.018. In contrast with some previous works, we have not found any signature of canonical spin glass behavior down to $\approx$15mK. Instead, below $\approx$300mK we observed dynamic magnetism characterized by a single correlation time with a temperature independent fluctuation rate. We observed that this low temperature fluctuation rate increases with x up to 0.08, above which it levels off. The 300mK energy scale corresponds to the Ho3+ hyperfine interaction strength, suggesting that the hyperfine interaction may be intimately involved with the spin dynamics in this system

Evaluating the impact of flexible alcohol trading hours on violence: an interrupted time series analysis.

BACKGROUND: On November 24(th) 2005, the Government of England and Wales removed regulatory restrictions on the times at which licensed premises could sell alcohol. This study tests availability theory by treating the implementation of Licensing Act (2003) as a natural experiment in alcohol policy. METHODS: An interrupted time series design was employed to estimate the Act's immediate and delayed impact on violence in the City of Manchester (Population 464,200). We collected police recorded rates of violence, robbery, and total crime between the 1st of February 2004 and the 31st of December 2007. Events were aggregated by week, yielding a total of 204 observations (95 pre-, and 109 post-intervention). Secondary analysis examined changes in daily patterns of violence. Pre- and post-intervention events were separated into four three-hour segments 18∶00-20∶59, 21∶00-23.59, 00∶00-02∶59, 03∶00-05∶59. RESULTS: Analysis found no evidence that the Licensing Act (2003) affected the overall volume of violence. However, analyses of night-time violence found a gradual and permanent shift of weekend violence into later parts of the night. The results estimated an initial increase of 27.5% between 03∶00 to 06∶00 (ω = 0.2433, 95% CI = 0.06, 0.42), which increased to 36% by the end of the study period (δ = -0.897, 95% CI = -1.02, -0.77). CONCLUSIONS: This study found no evidence that a national policy increasing the physical availability of alcohol affected the overall volume of violence. There was, however, evidence suggesting that the policy may be associated with changes to patterns of violence in the early morning (3 a.m. to 6 a.m.)