Cryptic female choice favours sperm from major histocompatibility complex-dissimilar males

Cryptic female choice may enable polyandrous females to avoid inbreeding or bias offspring variability at key loci after mating. However, the role of these genetic benefits in cryptic female choice remains poorly understood. Female red junglefowl, Gallus gallus, bias sperm use in favour of unrelated males. Here, we experimentally investigate whether this bias is driven by relatedness per se, or by similarity at the major histocompatibility complex (MHC), genes central to vertebrate acquired immunity, where polymorphism is critical to an individual's ability to combat pathogens. Through experimentally controlled natural matings, we confirm that selection against related males' sperm occurs within the female reproductive tract but demonstrate that this is more accurately predicted by MHC similarity: controlling for relatedness per se, more sperm reached the eggs when partners were MHC-dissimilar. Importantly, this effect appeared largely owing to similarity at a single MHC locus (class I minor). Further, the effect of MHC similarity was lost following artificial insemination, suggesting that male phenotypic cues might be required for females to select sperm differentially. These results indicate that postmating mechanisms that reduce inbreeding may do so as a consequence of more specific strategies of cryptic female choice promoting MHC diversity in offspring

Gravitational Collapse and Fragmentation in Molecular Clouds with Adaptive Mesh Refinement

We describe a powerful methodology for numerical solution of 3-D self-gravitational hydrodynamics problems with extremely high resolution. Our method utilizes the technique of local adaptive mesh refinement (AMR), employing multiple grids at multiple levels of resolution. These grids are automatically and dynamically added and removed as necessary to maintain adequate resolution. This technology allows for the solution of problems in a manner that is both more efficient and more versatile than other fixed and variable resolution methods. The application of AMR to simulate the collapse and fragmentation of a molecular cloud, a key step in star formation, is discussed. Such simulations involve many orders of magnitude of variation in length scale as fragments form. In this paper we briefly describe the methodology and present an illustrative application for nonisothermal cloud collapse. We describe the numerical Jeans condition, a criterion for stability of self-gravitational hydrodynamics problems. We show the first well-resolved nonisothermal evolutionary sequence beginning with a perturbed dense molecular cloud core that leads to the formation of a binary system consisting of protostellar cores surrounded by distinct protostellar disks. The scale of the disks, of order 100 AU, is consistent with observations of gaseous disks surrounding single T-Tauri stars and debris disks surrounding systems such as $\beta$ Pictoris.Comment: 10 pages, 6 figures (color postscript). To appear in the proceedings of Numerical Astrophysics 1998, Tokyo, March 10-13, 199

Economic Impact of Cruise Tourism in Atlantic Canada: Is Cruise Passenger Spending exaggerated?

ECONOMIC IMPACT OF CRUISE TOURISM IN ATLANTIC CANADA IS CRUISE PASSENGER SPENDING EXAGGERATED? Introduction Cruise tourism is of increasing importance in Atlantic Canada. Average annual growth during the 1990-2015 period in Halifax was 9.24% (Transport Canada, 2016). Total cruise ship visitors to Halifax has grown tenfold over the last two decades, from approximately 24,000 in 1990 to 238,217 in 2015 (Transport Canada, 2016). The number of cruise ship visitors to Newfoundland & Labrador increased from 10,000 in 2000 to 50,000 in 2015. The growth of cruise tourism in the last decades is accompanied by the expected growth of benefits for the hosting ports. On the surface, it is reasonable to expect the cruise tourism to generate economic benefits emanating from spending by various parties (passengers, cruise lines, tour providers, etc.). However, there is growing evidence that studies supported or done by the cruise industry (e.g., Business Research & Economic Advisors (BREA)/Cruise Lines International Association (CLIA)) which serve as the foundation for assessing the economic benefits of cruise tourism, may be exaggerated. Literature While the cruise industry reported economic impacts are significant, there are deficiencies in such self-reported/commissioned statistics by cruise associations such as BREA and CLIA (Larsen et. Al., 2013; Falkenhaug, 2012; Scarfe, 2011; Klein 2011; Brida and Zappata, 2011). Economic impact estimates reported by the cruise lines suffer from a variety of theoretical and empirical problems. Benefits, computed in the form of tourism spending by passengers, are commonly calculated by taking the average expenditure times the number of passengers. Ports are quick to claim that each cruise passenger spends more than $100 during a port call and then simply deduces that a cruise with 4000 passengers and 2000 crew generates revenue of$6 million (Brida and Zapata, 2010). However, as Stavanger (2012) demonstrates, 20-40% of the passengers do not leave the ship during a stop-over. Using average expenditure values from other studies (ports) is arbitrary, since expenses and their effects will differ depending upon: 1) Type of port function (turn around/port of call), which will impact length of stay, 2) Market segment in terms of ship type, passenger type and nationality, all of which can vary depending upon the time of year, and 3) Attractions/products/services offered in a specific area ( Klein 2011 and Torbianelli 2012). To the extent a data collection strategy of surveying cruise ship passengers and crew fails to account for these factors, the results will be biased and the economic impact results inaccurate. Method This study draws on data collected during the 2016 cruise season in the four major ports in Atlantic Canada (i.e., Halifax, Nova Scotia; Saint John, New Brunswick; Charlottetown, Prince Edward Island; and St. John’s, Newfoundland). Data was subsequently gathered in 2017, however for purposes here we draw mainly on the data for the Port of Halifax in 2016. The Halifax data includes cruise ship passengers visiting the port of Halifax between April 30th and October 28th. A total of 2,205 surveys were collected from 100 (75%) of the 133 cruise ships that visited the port. Passengers were randomly surveyed at the port area beginning 2 hours after the ship’s arrival and continuing until 1 hour before the ship’s departure. The 23 cruise lines visiting the port were divided for purposes of analysis into four groups; the Halifax Port Authority concurred with the categories. The largest number of passengers (42.5%) are brought by mass market cruises. Close behind are passengers on Premium cruise lines (41%), the remainder is split almost evenly between Luxury cruise lines and European cruise lines. This study attempts to understand the disparity between passenger spending figures produced by cruise industry supported studies, [specifically a 2017 study (2016 data) completed by Business Research & Economic Advisors (BREA)) versus studies undertaken by other, often independent, researchers (specifically our study) for the same geographic (Atlantic Canada)) area. Average spending per person is compared between this study which uses a probability sampling method versus the BREA study issued in April 2017 that did not. A critical element in producing unbiased sample statistics is the degree to which the sample of respondents in the passenger spending survey correspond to the actual universe (all ship arrivals in the year) of cruise ship and cruise passenger visits. The risk of biased results is reduced if the collected sample is representative of the population. In the BREA study, Luxury and European cruise visitors constitute 16.8% of passengers landing in early Season, yet no respondents were drawn from this group. A further bias is introduced by Mass Market visitors making up 42.7% of the cruise passengers in early season yet they are 64.4% of the early season respondents to the BREA survey. In contrast, the data collected in this study is closely aligned with the proportions of cruise vessel visits. Because all cruise ships visiting in the early season were surveyed, the sample we drew was from the universe of cruise ships visiting Halifax and more closely aligns with actual cruise visitor numbers and proportions than those based on the ships sampled in the BREA study. Findings/Results From an economic perspective, the significance of having a biased sample across market segment is made relevant by the fact that passenger spending differed by market segment. Spending was significantly greater for Mass Market cruise visitors ($70.44) than visitors on Premium lines ($60.02), Luxury lines ($57.84) and European lines ($52.79). The effect of oversampling the cruise market category, where spending is highest, is to artificially increase the overall per passenger spending. The BREA’s sampling frame over-represents Mass Market cruise visitors by 50%. At the same time, this market segment spends per passenger 10% more than the population average; more than 15% greater than the Premium lines. There is a cumulative impact of these two conditions, which is likely to bias the derived average spending figure, which is then used as the basis for computing economic impact. The average spending per passenger in this study was $63.57; in the BREA study it was 31.5$83.84. The significance of this difference in per passenger spending can be illustrated for Halifax (Atlantic Canada’s largest port for cruise visits) which had 220,351 passenger visits in 2016. Using the BREA figure for average spending, total spending would be $18.4 million, using our estimate, total spending would be$14.0 million. The importance of potential factors that may influence the cruise passenger spending in a port are also investigated. More specifically, regression analysis was conducted to investigate the influence of potential explanatory variables on the cruise passenger spending in Halifax using our data from the 2016 cruise season. The dependent variable of the analysis is the per capita passenger spending in Halifax. Of particular interest is that passenger spending is dependent on demographic characteristics, cruise industry segment, precipitation/temperature and port order placement in cruise itinerary. Conclusion The research outlines the importance of using accepted methods of probability sampling. Results otherwise may be inaccurate and mislead per passenger spending. As shown, the sample of ships included in BREA’s study of passenger spending in Halifax overstated by 31.5% the amount spent. Our data suggests this is caused by oversampling mass market cruise passengers, who comparatively spend significantly more than all other cruise passengers visiting Halifax. The inflated number is then used in determining economic impact, which consequently is an overstatement. Finally, the regression analysis shows that passenger spending is influenced by socio-economic/demographic/weather/itinerary related variables. A cleared understanding of the variables driving visitors spending could allow ports to adopt strategies that can maximize the local economic benefits. The provision of benchmark data enables assessment of current and future policies related to cruise tourism. An economic perspective is important to the development and management of tourism resources and can play a key role in driving tourism initiatives that balance economic/social/cultural benefits and costs. References BREA. (2017). The Economic Contribution of the International Cruise Industry in Canada A Survey-based Analysis of the Impacts of Passenger, Crew and Cruise Line Spending (Accessed July 10, 2017) Brida, J.G., and Zapata, S. (2011). Cruise Tourism: Economic, Socio-cultural and Environmental impacts. International Journal of Leisure and Tourism Marketing, 1(3), 205-226. Falkenhaug, J. (2012). Where would we have been without cruise ships.? Retrieved from: https://web.retriever-info.com/services/archive.html?method=displayDocument&documentd=0200212120120827799347&serviceId=2 Klein, R.A. (2011). Responsible Cruise Tourism: Issues of Cruise Tourism and Sustainability. Journal of Hospitality and Tourism Management, 18, 107–116. Larsen, S., Wolff, K. Marnburg, E. and Ogaard, T. (2013). Tourism Management Perspectives. 6, 142-148. Scarfe, B.L. (2011). Victoria as a Port-of-Call: The Costs and Benefits of Cruise Ship Visits. A report prepared for the James Bay Neighbourhood Association. Stavanger, Aftenblad (2012). Butikkene kan takke cruiseturistene for 3 millioner kroner. Retrived from http://www.aftenbladet.no/nyheter/lokalt/stavanger/Butikkene-kantakke-cruiseturistene-for-3-millioner-kroner-2942999.html Torbianelli, V. (2012). The local economic impact of cruises: From figures to the active policies of the European harbor cities. Scientific Journal of Maritime Research, 1, 139-150. Transport Canada Press Release, October 26, 2016).

Basolateral Junction Proteins Regulate Competition for the Follicle Stem Cell Niche in the Drosophila Ovary

Epithelial stem cells are routinely lost or damaged during adult life and must therefore be replaced to maintain homeostasis. Recent studies indicate that stem cell replacement occurs through neutral competition in many types of epithelial tissues, but little is known about the factors that determine competitive outcome. The epithelial follicle stem cells (FSCs) in the Drosophila ovary are regularly lost and replaced during normal homeostasis, and we show that FSC replacement conforms to a model of neutral competition. In addition, we found that FSCs mutant for the basolateral junction genes, lethal giant larvae (lgl) or discs large (dlg), undergo a biased competition for niche occupancy characterized by increased invasion of neighboring FSCs and reduced loss. Interestingly, FSCs mutant for a third basolateral junction gene, scribble (scrib), do not exhibit biased competition, suggesting that Lgl and Dlg regulate niche competition through a Scrib-independent process. Lastly, we found that FSCs have a unique cell polarity characterized by broadly distributed adherens junctions and the lack of a mature apical domain. Collectively, these observations indicate that Lgl and Dlg promote the differentiation of FSC progeny to a state in which they are less prone to invade the neighboring niche. In addition, we demonstrate that the neutral drift model can be adapted to quantify non-neutral behavior of mutant clones

Volatile abundances and oxygen isotopes in basaltic to dacitic lavas on mid-ocean ridges: The role of assimilation at spreading centers

Most geochemical variability in MOR basalts is consistent with low- to moderate-pressure fractional crystallization of various mantle-derived parental melts. However, our geochemical data from MOR high-silica glasses, including new volatile and oxygen isotope data, suggest that assimilation of altered crustal material plays a significant role in the petrogenesis of dacites and may be important in the formation of basaltic lavas at MOR in general. MOR high-silica andesites and dacites from diverse areas show remarkably similar major element trends, incompatible trace element enrichments, and isotopic signatures suggesting similar processes control their chemistry. In particular, very high Cl and elevated H2O concentrations and relatively light oxygen isotope ratios (~5.8‰ vs. expected values of ~6.8‰) in fresh dacite glasses can be explained by contamination of magmas from a component of ocean crust altered by hydrothermal fluids. Crystallization of silicate phases and Fe-oxides causes an increase in δ18O in residual magma, but assimilation of material initially altered at high temperatures results in lower δ18O values. The observed geochemical signatures can be explained by extreme fractional crystallization of a MOR basalt parent combined with partial melting and assimilation (AFC) of amphibole-bearing altered oceanic crust. The MOR dacitic lavas do not appear to be simply the extrusive equivalent of oceanic plagiogranites. The combination of partial melting and assimilation produces a distinct geochemical signature that includes higher incompatible trace element abundances and distinct trace element ratios relative to those observed in plagiogranites. © 2011 Elsevier B.V

Spatially valid proprioceptive cues improve the detection of a visual stimulus

Vision and proprioception are the main sensory modalities that convey hand location and direction of movement. Fusion of these sensory signals into a single robust percept is now well documented. However, it is not known whether these modalities also interact in the spatial allocation of attention, which has been demonstrated for other modality pairings. The aim of this study was to test whether proprioceptive signals can spatially cue a visual target to improve its detection. Participants were instructed to use a planar manipulandum in a forward reaching action and determine during this movement whether a near-threshold visual target appeared at either of two lateral positions. The target presentation was followed by a masking stimulus, which made its possible location unambiguous, but not its presence. Proprioceptive cues were given by applying a brief lateral force to the participant’s arm, either in the same direction (validly cued) or in the opposite direction (invalidly cued) to the on-screen location of the mask. The d′ detection rate of the target increased when the direction of proprioceptive stimulus was compatible with the location of the visual target compared to when it was incompatible. These results suggest that proprioception influences the allocation of attention in visual spac

Double quantum dot with integrated charge sensor based on Ge/Si heterostructure nanowires

Coupled electron spins in semiconductor double quantum dots hold promise as the basis for solid-state qubits. To date, most experiments have used III-V materials, in which coherence is limited by hyperfine interactions. Ge/Si heterostructure nanowires seem ideally suited to overcome this limitation: the predominance of spin-zero nuclei suppresses the hyperfine interaction and chemical synthesis creates a clean and defect-free system with highly controllable properties. Here we present a top gate-defined double quantum dot based on Ge/Si heterostructure nanowires with fully tunable coupling between the dots and to the leads. We also demonstrate a novel approach to charge sensing in a one-dimensional nanostructure by capacitively coupling the double dot to a single dot on an adjacent nanowire. The double quantum dot and integrated charge sensor serve as an essential building block required to form a solid-state spin qubit free of nuclear spin.Comment: Related work at http://marcuslab.harvard.edu and http://cmliris.harvard.ed

In-street wind direction variability in the vicinity of a busy intersection in central London

We present results from fast-response wind measurements within and above a busy intersection between two street canyons (Marylebone Road and Gloucester Place) in Westminster, London taken as part of the DAPPLE (Dispersion of Air Pollution and Penetration into the Local Environment; www.dapple.org.uk) 2007 field campaign. The data reported here were collected using ultrasonic anemometers on the roof-top of a building adjacent to the intersection and at two heights on a pair of lamp-posts on opposite sides of the intersection. Site characteristics, data analysis and the variation of intersection flow with the above-roof wind direction (θref) are discussed. Evidence of both flow channelling and recirculation was identified within the canyon, only a few metres from the intersection for along-street and across-street roof-top winds respectively. Results also indicate that for oblique rooftop flows, the intersection flow is a complex combination of bifurcated channelled flows, recirculation and corner vortices. Asymmetries in local building geometry around the intersection and small changes in the background wind direction (changes in 15-min mean θref of 5–10 degrees) were also observed to have profound influences on the behaviour of intersection flow patterns. Consequently, short time-scale variability in the background flow direction can lead to highly scattered in-street mean flow angles masking the true multi-modal features of the flow and thus further complicating modelling challenges

Variables associated with odds of finishing and finish time in a 161-km ultramarathon

We sought to determine the degree to which age, sex, calendar year, previous event experience and ambient race day temperature were associated with finishing a 100-mile (161-km) trail running race and with finish time in that race. We computed separate generalized linear mixed-effects regression models for (1) odds of finishing and (2) finish times of finishers. Every starter from 1986 to 2007 was used in computing the models for odds of finishing (8,282 starts by 3,956 individuals) and every finisher in the same period was included in the models for finish time (5,276 finishes). Factors associated with improved odds of finishing included being a first-time starter and advancing calendar year. Factors associated with reduced odds of finishing included advancing age above 38 years and warmer weather. Beyond 38 years of age, women had worse odds of finishing than men. Warmer weather had a similar effect on finish rates for men and women. Finish times were slower with advancing age, slower for women than men, and less affected by warm weather for women than for men. Calendar year was not associated with finish time after adjustment for other variables