Towards Rogue Wave Characterization in False Bay, South Africa

Rogue waves are extreme oceanic waves which exceed twice the significant wave height of the wave record. In False Bay, South Africa, a shallow sea mount called rocky bank was suggested by Shipley (1964) to be the cause for increased wave energy along the eastern periphery of False Bay, where it is not uncommon for coastal users, particularly rock fishermen, to be washed off of the rocky coastline. The shallow bathymetry associated with rocky bank refracts the incoming open ocean swell and is thought to focus the wave energy toward sections of this coastline. This investigation aims to understand which offshore wave conditions could be conducive to rogue wave development along the eastern periphery of False Bay, South Africa. To do so, the phase-averaging spectral wave numerical model SWAN was used to investigate various wave conditions which are known to enter False Bay. The focusing effect which rocky bank supposedly has on the incoming wave energy was investigated by deepening and shallowing rocky bank's depth. This study showed that rocky bank does cause a varying degree of wave focusing which appears to be most dependent on the wave period, with higher wave periods leading to greater extents of refraction. According to this study, the average conditions which impact the south-western coastline of South Africa are conducive to wave focusing by rocky bank and despite the rarity of rogue wave events, coastal users are still affected by them. Calm seas have the ability to mislead users that make use of these dangerous rocky coasts, when the event of a rogue wave in small seas can still be sufficient to wash a person into the sea. A study by de Vos & Rautenbach (2019) suggested that users are at a higher risk, for a variety of coastal activities, during (seemingly) good conditions due to the increased human exposure. Since this study only simulated monochromatic wave conditions, one would expect the results to be significantly different if multiple swell systems were simulated concurrently, as this introduces the possibility of the dispersive focusing mechanism for swells that travel at different speeds and thus increasing the likelihood of a rogue wave. The knowledge acquired from this study is a great step towards understanding the wave climate of False Bay. This information can be used to implement possible warning systems which would hopefully be respected by the community and ultimately lessen the lives lost to extreme waves along False Bay's 'Death coast'

A faster tree-decomposition based algorithm for counting linear extensions

We consider the problem of counting the linear extensions of an n-element poset whose cover graph has treewidth at most t. We show that the problem can be solved in time Õ(nt+3), where Õ suppresses logarithmic factors. Our algorithm is based on fast multiplication of multivariate polynomials, and so differs radically from a previous Õ(nt+4)-time inclusion–exclusion algorithm. We also investigate the algorithm from a practical point of view. We observe that the running time is not well characterized by the parameters n and t alone, fixing of which leaves large variance in running times due to uncontrolled features of the selected optimal-width tree decomposition. For selecting an efficient tree decomposition we adopt the method of empirical hardness models, and show that it typically enables picking a tree decomposition that is significantly more efficient than a random optimal-width tree decomposition. © Kustaa Kangas, Mikko Koivisto, and Sami Salonen; licensed under Creative Commons License CC-BY.Peer reviewe

Tell Your Story Well: How Embedded Librarians Demonstrate and Communicate Their Value

SLA Embedded Librarians Caucus Conference panel session from the Special Libraries Association 2018 Annual Conference, selected for the SLA "Best Of" Webinar series of the seven most highly-rated sessions from this SLA 2018 conference. Embedded librarians have unique opportunities and challenges in demonstrating and communicating their value. Metrics and communications have to be tailored to each situation, and can depend on the type of organization, the organization’s mission and strategy, and the personalities involved. In this panel session, experienced managers and librarians shared perspectives, principles, and examples for making sure others in your organization (especially the higher ups) understand the value librarians are adding in their embedded role. Moderator: Nadine Anderson. Panelists: *Jennifer Martin, Associate Librarian, Arizona Health Sciences Library *Ethel M. Salonen, Principal, Ollin AssociatesSLA Embedded Librarians Caucus Conference panel session from the Special Libraries Association 2018 Annual Conference, selected for the SLA "Best Of" Webinar series of the seven most highly-rated sessions from this SLA 2018 conference.https://deepblue.lib.umich.edu/bitstream/2027.42/150201/1/Tell Your Story Well - How Embedded Librarians Demonstrate and Communicate Their Value.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150201/2/2018-10-02 14.03 How Embedded Librarians Demonstrate and Communicate Their Value.mp4Description of Tell Your Story Well - How Embedded Librarians Demonstrate and Communicate Their Value.pdf : Presentation SlidesDescription of 2018-10-02 14.03 How Embedded Librarians Demonstrate and Communicate Their Value.mp4 : Webinar Recordin

Enhanced dielectrophoresis of nanocolloids by dimer formation

We investigate the dielectrophoretic motion of charge-neutral, polarizable nanocolloids through molecular dynamics simulations. Comparison to analytical results derived for continuum systems shows that the discrete charge distributions on the nanocolloids have a significant impact on their coupling to the external field. Aggregation of nanocolloids leads to enhanced dielectrophoretic transport, provided that increase in the dipole moment upon aggregation can overcome the related increase in friction. The dimer orientation and the exact structure of the nanocolloid charge distribution are shown to be important in the enhanced transport

A Frequency Tuning Method for a Planar Inverted-F Antenna

A novel method is presented for electrically tuning the frequency of a planar inverted-F antenna (PIFA). A tuning circuit, comprising an RF switch and discrete passive components, has been completely integrated into the antenna element, which is thus free of dc wires. The proposed tuning method has been demonstrated with a dual-band PIFA capable of operating in four frequency bands. The antenna covers the GSM850, GSM900, GSM1800, PCS1900 and UNITS frequency ranges with over 40% total efficiency. The impact of the tuning circuit on the antenna's efficiency and radiation pattern have been experimentally studied through comparison with the performance of a reference antenna not incorporating the tuning circuit. The proposed frequency tuning concept can be extended to more complex PIFA structures as well as other types of antennas to give enhanced electrical performance.</p

CT imaging of dogs with perineal hernia reveals large prostates with morphological and spatial abnormalities

The etiology of canine perinea) hernia (PH) remains unclear, although as a disease of older male dogs, it is likely to be hormonal. The role of the prostate in the formation of PH has been questioned; however, prospective and systematic evaluation of prostates in these dogs is absent in the literature. In this prospective case-control study, CT imaging was used to assess prostatic changes in dogs with PH (n = 46) and compare these findings with those of intact age-matched male dogs (n = 23). Using the OsiriX (R) DICOM viewer, we measured prostatic volume and correlated it with the size of the dog by using the length of the sixth lumbar vertebra. In addition, we recorded spatial and morphological changes of the prostate, such as heterogenicity, intra- and paraprostatic cysts, and mineralizations, as well as prostatic location and rotation. We found that dogs with PH had larger prostates (P < .001) that more often contained cysts (P < .001) and had larger cyst diameters (P = .013) than age-matched controls. Prostates of PH dogs also contained paraprostatic cysts (17.4%) and focal mineralizations (32.6%), which were absent in the control group. Abnormal rotation and location of the prostate were common in dogs with PH. In conclusion, these findings support the use of CT as an adjunct diagnostic imaging modality for the evaluation of the prostate in dogs with PH. Further studies are needed to evaluate nonprostatic CT findings in the pelvic cavity of PH dogs.Peer reviewe

Socio-Demographic Factors, Gambling Behaviour, and the Level of Gambling Expenditure : A Population-Based Study

The aim of this study was to examine the relationship between socio-demographic factors, gambling behaviour, and the level of gambling expenditure. The data were drawn from the population-based Gambling Harms Survey 2016 and 2017 conducted in Finland. The data were linked to register-based variables. Past-year gamblers were included (Wave 1; n=5 805, both Waves; n=2 165). The study showed that of the 4.2% of gamblers that produced 50.0% of the total GE in 2016, 33.1% of the GE was produced by those with a gambling problem and 43.3% by those with at-risk gambling pattern. Compared to gamblers in the lowest GE group, those in the highest GE group were more likely to be men, aged 25 or older, with upper secondary education, have a high income, be on dis- ability pension or sickness allowance, be frequent gamblers, gambling at least six game types, and showing at-risk and problem gambling patterns. Cumulative weekly GE by income tertiles remained fairly stable between the years. The results suggest that GE is highly concentrated. Among the small group of high-intensity consumers, the majority of the revenue comes from at-risk and problem gambling. Participants in the low GE group differ from those in the intermediate and high GE groups in terms of socio-demographics and gambling behaviour.The aim of this study was to examine the relationship between socio-demographic factors, gambling behaviour, and the level of gambling expenditure. The data were drawn from the population-based Gambling Harms Survey 2016 and 2017 conducted in Finland. The data were linked to register-based variables. Past-year gamblers were included (Wave 1; n=5 805, both Waves; n=2 165). The study showed that of the 4.2% of gamblers that produced 50.0% of the total GE in 2016, 33.1% of the GE was produced by those with a gambling problem and 43.3% by those with at-risk gambling pattern. Compared to gamblers in the lowest GE group, those in the highest GE group were more likely to be men, aged 25 or older, with upper secondary education, have a high income, be on dis- ability pension or sickness allowance, be frequent gamblers, gambling at least six game types, and showing at-risk and problem gambling patterns. Cumulative weekly GE by income tertiles remained fairly stable between the years. The results suggest that GE is highly concentrated. Among the small group of high-intensity consumers, the majority of the revenue comes from at-risk and problem gambling. Participants in the low GE group differ from those in the intermediate and high GE groups in terms of socio-demographics and gambling behaviour.Peer reviewe