Turning big bang into big bounce: II. Quantum dynamics

We analyze the big bounce transition of the quantum FRW model in the setting of the nonstandard loop quantum cosmology (LQC). Elementary observables are used to quantize composite observables. The spectrum of the energy density operator is bounded and continuous. The spectrum of the volume operator is bounded from below and discrete. It has equally distant levels defining a quantum of the volume. The discreteness may imply a foamy structure of spacetime at semiclassical level which may be detected in astro-cosmo observations. The nonstandard LQC method has a free parameter that should be fixed in some way to specify the big bounce transition.Comment: 14 pages, no figures, version accepted for publication in Class. Quant. Gra

Low metabolic activity of biofilm formed by Enterococcus faecalis isolated from healthy humans and wild mallards (Anas platyrhynchos)

It is widely known that Enterococcus faecalis virulence is related to its biofilm formation. Although Enterococci are common commensal organisms of the gastrointestinal tract, the difference between commensal and pathogen strains remain unclear. In this study, we compare the biochemical profile of the biofilms formed by two groups of medical and two groups of commensal strains. The medical strains were isolated as pathogens from infections of urinary tract and other infections (wounds, pus and bedsores), and the commensal strains were taken from faeces of healthy volunteers and faeces of wild mallards (Anas platyrhynchos) living in an urban environment. The properties of biofilms formed by medical and commensal strains differed significantly. Commensal strains showed lower metabolic activity and glucose uptake and higher biofilm biomass than the medical ones. Consistent with glucose uptake experiments, we found that the glucose dehydrogenase gene was more expressed in medical strains. These results indicate that higher metabolic activity and lower protein concentration of E. faecalis cells within biofilms are formed during infections.This work was supported by the Medical University of Gdansk research grant (GUMed W-65) and was financed partly by University of Gdansk research grant (BW 1440-5-0099-7). We are grateful to Katarzyna Zolkos for her help in catching mallards and Magdalena Remisiewicz for correcting the English. Catarina Seabra helped in preparing assays

Protected area characteristics that help waterbirds respond to climate warming

Protected area networks help species respond to climate warming. However, the contribution of a site's environmental and conservation-relevant characteristics to these responses is not well understood. We investigated how composition of nonbreeding waterbird communities (97 species) in the European Union Natura 2000 (N2K) network (3018 sites) changed in response to increases in temperature over 25 years in 26 European countries. We measured community reshuffling based on abundance time series collected under the International Waterbird Census relative to N2K sites' conservation targets, funding, designation period, and management plan status. Waterbird community composition in sites explicitly designated to protect them and with management plans changed more quickly in response to climate warming than in other N2K sites. Temporal community changes were not affected by the designation period despite greater exposure to temperature increase inside late-designated N2K sites. Sites funded under the LIFE program had lower climate-driven community changes than sites that did not received LIFE funding. Our findings imply that efficient conservation policy that helps waterbird communities respond to climate warming is associated with sites specifically managed for waterbirds

Preen gland - do we know all about functions of its secretion?

Gruczoł kuprowy jest jedynym gruczołem skórnym, poza małżowinowymi u kuraków, występującym u większości ptaków. Położony jest po stronie grzbietowej ponad ostatnimi kręgami ogonowymi. Gruczoł produkuje tłustą wydzielinę, którą ptak rozprowadza po upierzeniu przy pomocy dzioba. Wydzielina gruczołu kuprowego jest złożoną mieszaniną związków organicznych, głównie wosków, których skład może różnić się w zależności od gatunku, sezonu, wieku i płci ptaków czy stosowanej diety. Funkcje wydzieliny gruczołu kuprowego wciąż są dyskutowane. Najczęściej wymienia się ochronę piór przed wilgocią i nadmiernym ścieraniem czy też ektopasożytami. Do niedawna uważano też, że jest ona źródłem witaminy D, jednak współczesne badania zupełnie tego nie potwierdziły. Wraz z rozwojem technik analizy składu chemicznego tej wydzieliny powstają nowe hipotezy na temat roli pełnionej przez gruczoł kuprowy.Preen gland (also known as uropygial or oil gland) is a major skin gland that occurs in most birds. It is located dorsally at the base of the tail and produces oily secretion which birds smear onto their feathers with the beak. The preen gland secretion is a complex mixture of diverse organic compounds, mainly waxes, which may vary among birds depending on the species, season, age and gender of bird, and diet. The functions of preen gland secretion are still under discussion. Most often they are said to provide plumage maintenance, protection of feathers against moisture, abrasion or ectoparasites; until recently the secretion was also regarded erroneously as the source of vitamin D. However, contemporary studies negate some of these functions and new ones are being suggested

Factors affecting apparent survival and resighting probability of wintering mallards Anas platyrhynchos: A case study from a small town in north-eastern Poland

Survival of adults is a key demographic parameter affecting avian population dynamics. In urban areas, e.g., city parks, birds stay in winter in large numbers where they have access to a multitude of food sources due to human activities, which is one of the key factors that attract birds into the cities. Our study estimates apparent survival of mallard ducks Anas platyrhynchos between non-breeding seasons in a small town in the coldest region in north-eastern Poland between 2005 and 2017. We found lower survival estimates for females (juveniles: 0.54; adults: 0.59) than males (juveniles: 0.76; adults: 0.72) and probabilities of resighting individuals in the next non-breeding season were higher if the bird was resighted in the study area during the prior breeding period. Thus, we conclude that sedentary mallards from the local urban population have relatively high survival, which may be explained by lower pressure from raptors, lack of hunting and higher winter temperatures in the urban site. Additionally, winter temperature was negatively related to resighting probability in the next non-breeding season. Resighting probability was time-dependent with a bimodal pattern with maximal estimates of 0.48 in 2007/2008 and 0.98 in 2013/2014, 0.98 in 2014/2015, 1.00 in 2015/2016. These results are most likely related to volunteers’ activity that increased due to organized official competition with special awards during those seasons. Considering the fact that the type of ring (metal or plastic coloured) significantly influenced the probabilities of resighting of individuals, it is recommended that apparent survival studies on birds be conducted using colour rings. Moreover, we encourage to collect more capture-mark-recapture data to enable accurate estimations of duck survival, which not the least is a prerequisite for successful management and conservation efforts

Investigations of sexual dimorphism in live Kittlitz’s Plover Charadrius pecuarius from inland South Africa

Charadrius plovers generally show little sexual or seasonal dimorphism in size and coloration, but most published measurements come from museum specimens. We aimed to determine sexual size dimorphism in live Kittlitz’s Plovers Charadrius pecuarius, based on measurements of 96 males and 112 females ringed at Barberspan Bird Sanctuary (North West province, South Africa) between February 2008 and October 2009 and sexed by DNA analysis. The females were significantly heavier than the males in September–October, but their mass decreased significantly from September to the end of March (b = -0.10, t = 3.82, P = 0.0002), likely because of egg laying. Body mass has limited utility for sexing, because heavy birds with high fat scores of both sexes, possibly itinerants, occurred in all months. Tarsus-and-toe length differed between sexes (P = 0.066). Wing length of birds with old primaries decreased in September–October (ANCOVA, F1,153 = 8.84, P = 0.003), but did not differ between the sexes (ANCOVA, F1,153 = 0.23, P = 0.626). Wing length for birds with fresh feathers, total head length, bill length, tarsus length and height of the white forehead patch did not differ between sexes. We attribute this lack of any clear sexual dimorphism to the species’ monogamous mating system and shared parental care, and to its simple terrestrial displays, which would likely result in weak intersexual selection.OSTRICH 2011, 82(2): 135–13

Data from: Leukocyte profiles are associated with longevity and survival, but not migratory effort: a comparative analysis of shorebirds

1. Assessment of leukocyte profiles has become an increasingly popular tool in the fields of ecology and ecophysiology. The ratio of heterophils to lymphocytes (H/L ratio) is of special utility, as it reflects physiological adaptation of an organism to cope either with an infection through injury (via heterophils) or a communicable disease (via lymphocytes). Thus, elevated H/L ratios may constitute an adaptation to risky environments (i.e. associated with high risk of injury). While intra-population variation in avian H/L ratio has been extensively studied, we are aware of no studies that linked this trait to life-history components at the inter-specific level. 2. We measured H/L ratio in over 400 shorebirds from 19 species during their autumn migration through Central Europe. Phylogenetically informed comparative methods were used to test whether H/L ratio was related to: i) annual survival and lifespan; ii) migratory effort, as measured with total migration distance and migratory energy reserves; and iii) confounding variables such as body size or breeding latitude. 3. A relatively strong phylogenetic signal and spatial phylogenetic autocorrelation indicated that most diversification in shorebird H/L ratios occurred relatively early in radiation of this group. 4. Comparative analysis gave strong support for the negative associations of H/L ratio with residual lifespan and annual survival. In contrast, we found no support for the effect of migratory behaviour on H/L ratios, suggesting that leukocyte profiles in shorebirds may not constitute an important physiological adaptation for long-distance migration. 5. Our study provided the first comparative evidence for a link between H/L ratios and important life-history traits in birds. Strong negative associations with annual survival and residual lifespan indicate that leukocyte profiles may form an adaptive basis for life-history strategies in birds

The Effect of Floods on Nest Survival Probability of Common Sandpiper <i>Actitis hypoleucos</i> Breeding in the Riverbed of a Large Lowland European River

The natural valleys of large rivers provide suitable nesting and foraging sites for many bird species. In this study, we assess the effects of water fluctuations during the breeding season on Common Sandpipers’ nest survival on a semi-natural section of the Vistula River, and evaluate which tactics this species can adopt to minimise the effects on a long-term scale. Birds can avoid losses due to flooding by adjusting the timing of nesting to avoid the occurrence of extreme water conditions, and/or by choosing a safe nesting location. We found that nest location is a direct response to periodic high water, and the threat of flooding seems to be one of the important determinants of Common Sandpiper nest placement. The choice of nest location is not random, as 70% of pairs nested above a height that provides an 80% chance of avoiding flooding of the nest. For the lowest-lying nests found in this study, nesting success was reduced up to 92% because of inundation. Birds choose more elevated places, even during the second half of the season when the threat of flooding is lower. Their preference for nesting above a certain height does not change over the breeding season, which corresponds to the very small impact of the date of first egg laying on breeding success. Those who breed earlier in the season have a slightly higher risk of being flooded, but nesting in more elevated places reduces this risk much more than shifting the time of breeding