Home-range size in juveniles of the temperate reef fish, the common triplefin (Forsterygion lapillum)

An organism’s home range dictates the spatial scale on which important processes occur (e.g. competition and predation) and directly affects the relationship between individual fitness and local habitat quality. Many reef fish species have very restricted home ranges after settlement and, here, we quantify home-range size in juveniles of a widespread and abundant reef fish in New Zealand, the common triplefin (Forsterygion lapillum). We conducted visual observations on 49 juveniles (mean size = 35-mm total length) within the Wellington harbour, New Zealand. Home ranges were extremely small, 0.053 m2 ± 0.029 (mean ± s.d.) and were unaffected by adult density, body size or substrate composition. A regression tree indicated that home-range size sharply decreased ~4.5 juveniles m–2 and a linear mixed model confirmed that home-range sizes in high-density areas (>4.5 juveniles m–2) were significantly smaller (34%) than those in low-density areas (after accounting for a significant effect of fish movement on our home-range estimates). Our results suggest that conspecific density may have negative and non-linear effects on home-range size, which could shape the spatial distribution of juveniles within a population, as well as influence individual fitness across local density gradients.

Signal Reliability Improvement Using Selection Combining Based Macro-Diversity for Off-Body Communications At 868 MHz

This paper investigates the potential improvement in signal reliability for outdoor short-range off-body communications channels at 868 MHz using the macro-diversity offered by multiple co-located base stations. In this study, ten identical hypothetical base stations were positioned equidistantly around the perimeter of a rectangle of length 6.67 m and width 3.3 m. A body worn node was placed on the central chest region of an adult male. Five scenarios, each considering different user trajectories, were then analyzed to test the efficacy of using macro-diversity when the desired link is subject to shadowing caused by the human body. A number of selection combining based macro-diversity configurations consisting of four and then ten base stations were considered. It was found that using a macro-diversity system consisting of four base stations (or equivalently signal branches), a maximum diversity gain of 22.5 dB could be obtained while implementing a 10-base station setup this figure could be improved to 25.2 dB.

Sub-Arctic populations of European lobster (Homarus gammarus) in Northern Norway.

The European lobster is distributed throughout the south and western regions of the Norwegian coast. A previous lobster allozyme investigation (1993) in the Tysfjord region, north of the Arctic Circle demonstrated that the lobster population from this region was genetically different from lobster samples collected in other parts of Norway. More detailed investigation including supplementary extensive sampling and additional allozyme, microsatellite and mtDNA analyses are reported here. This investigation supports the genetic distinctness of the Tysfjord population and shows that this is mainly due to a reduction (60�70%) in gene diversity (observed heterozygosities and number of alleles) compared with lobsters from more southern regions. In addition to the Tysfjord region, the comprehensive sampling also included lobsters found in the adjacent Nordfolda fjord system. Genetic analyses provided evidence for significant differences between the lobster populations of Tysfjord and Nordfolda, even though they are separated by a coastal distance of only 142 km. The two populations were also different with regards to several biological characteristics such as body size. The genetic difference between these two geographically close populations is likely to be due to the local hydrological conditions, preventing larval dispersal between the fjord systems. Assessment of lobster abundance in the north-west region suggests that the sub-arctic lobster populations are geographically isolated.

Correlates of reproductive success in a population of nine-banded armadillos: a preliminary report.

We used microsatellite DNA markers to identify the putative parents of 69 litters of nine-banded armadillos (Dasypus novemcinctus) over 4 years. Male and female parents did not differ in any measure of body size in comparisons with nonparents. However, males observed paired with a female were significantly larger than unpaired males, although paired females were the same size as unpaired females. Females categorized as possibly lactating were significantly larger than females that were either definitely lactating or definitely not lactating. There was no evidence of assortative mating: body-size measurements of mothers were not significantly correlated with those of fathers. Nine-banded armadillos give birth to litters of genetically identical quadruplets. Mothers (but not fathers) of female litters were significantly larger than mothers of male litters, and maternal (but not paternal) body size was positively correlated with the number of surviving young within years, but not cumulatively. There were no differences in dates of birth between male and female litters, nor were there any significant relationships between birth date and maternal body size. Body size of either parent was not correlated with the body sizes of their offspring. Cumulative and yearly reproductive success did not differ between reproductively successful males and females. Average reproductive success (which included apparently unsuccessful individuals) also did not differ between males and females. The majority of adults in the population apparently failed to produce any surviving offspring, and even those that did usually did so in only 1 of the 4 years. This low reproductive success is unexpected, given the rapid and successful range extension of this species throughout the southeastern United States in this century.

Grassland-herbivore interactions: How do grazers coexist?

We develop a new approach to modeling grazing systems that links foraging characteristics (intake and digestive constraints) with resource dynamics via the probability of encounter with different grass heights. Three complementary models are presented: the generation of a grass height structure through selective grazing; investigating the conditions for consumer coexistence; and, using a simplified resource structure, the consequences for consumer abundance. The main finding is that coexistence between grazers differing in body size is possible if a single-resource type becomes differentiated in its height structure. Large grazers can facilitate food availability for smaller species but with the latter being competitively dominant. The relative preference given to different resource partitions is important in determining the nature of population interactions. Large-body and small-body grazer populations can interact through competitive, parasitic, commensalist, or amensalist relationships, depending on the way they partition the resource as well as their relative populations and the dynamics of resource renewal. The models provide new concepts of multispecies carrying capacity (stock equilibrium) in grazed systems with implications for conservation and management. We conclude that consumer species are not substitutable; therefore, the use of rangeland management concepts such as "livestock units" may be inappropriate.

The energy costs of sexual dimorphism in mole-rats are morphological not behavioural.

Different reproductive strategies of males and females may lead to the evolution of differences in their energetic costs of reproduction, overall energetic requirements and physiological performances. Sexual dimorphism is often associated with costly behaviours (e.g. large males might have a competitive advantage in fighting, which is energetically expensive). However, few studies of mammals have directly compared the energy costs of reproductive activities between sexes. We compared the daily energy expenditure (DEE) and resting metabolic rate (RMR) of males and females of two species of mole-rat, Bathyergus janetta and Georychus capensis (the former is sexually dimorphic in body size and the latter is not) during a period of intense digging when males seek females. We hypothesized that large body size might be indicative of greater digging or fighting capabilities, and hence greater mass-independent DEE values in males of the sexually dimorphic species. In contrast to this prediction, although absolute values of DEE were greater in B. janetta males, mass-independent values were not. No differences were apparent between sexes in G. capensis. By comparison, although RMR values were greater in B. janetta than G. capensis, no differences were apparent between the sexes for either species. The energy cost of dimorphism is most likely to be the cost of maintenance of a large body size, and not the cost of behaviours performed when an individual is large.

Low-pressure synthesis and characterisation of hydroxyapatite derived from mineralise red algae

There is a great need to design functional bioactive substitute materials capable of surviving harsh and diverse conditions within the human body. Calcium-phosphate ceramics, in particular hydroxyapatite are well established substitute materials for orthopaedic and dental applications. The aim of this study was to develop a bioceramic from alga origins suitable for bone tissue application. This was achieved by a novel synthesis technique using ambient pressure at a low temperature of 100 degrees C in a highly alkaline environment. The algae was characterised using SEM, BET, XRD and Raman Spectroscopy to determine its physiochemical properties at each stage. The results confirmed the successful conversion of mineralised red alga to hydroxyapatite, by way of this low-pressure hydrothermal process. Furthermore, the synthesised hydroxyapatite maintained the unique micro-porous structure of the original algae, which is considered beneficial in bone repair applications. (C) 2007 Elsevier B.V. All rights reserved.

Higher order statistics for the κ–μ distribution

Closed-form expressions for the level crossing rate and average fade duration of a kappa–mu distributed fading signal envelope are presented. The proposed equations are validated by reduction to known Rice, Rayleigh and Nakagami-m special cases. They are also compared with measured data obtained from field trials analysing human body to body radio channels and shown to provide good agreement.

Numerical analysis of bodyworn UHF antenna systems

Bodyworn antennas are found in a wide range of medical, military and personal communication applications, yet reliable communication from the surface of the human body still presents a range of engineering challenges. At UHF and microwave frequencies, bodyworn antennas can suffer from reduced efficiency due to electromagnetic absorption in tissue, radiation pattern fragmentation and variations in feed-point impedance. The significance and nature of these effects are system specific and depend on the operating frequency, propagation environment and physical constraints on the antenna itself. This paper describes how numerical electromagnetic modelling techniques such as FDTD (finite-difference time-domain) can be used in the design of bodyworn antennas. Examples are presented for 418 MHz, 916 .5 MHz and 2 . 45 GHz, in the context of both biomedical signalling and wireless personal-area networking applications such as the Bluetooth(TM)* wireless technology.

The natural plasma testosterone profile of male blue tits during the breeding season and its relation to song output

In male birds, the gonadal hormone testosterone (T) is known to influence territorial and mating behaviour. Plasma levels of T show seasonal fluctuations which vary in relation to mating system and social instability. First, we determined the natural T profile of male blue tits Parus caeruleus during the breeding season. We found that plasma levels of T increased at the onset of nest building. Thus, the increase in circulating T was not associated with territory establishment, nor with the fertile period of the males' mates. In most individuals, T levels dropped to values close to zero during the period of chick feeding. Second, we investigated the relationship between plasma levels of T and male age, size, and singing behaviour. During the mating period, T levels did not differ between 1 yr old and older males and did not correlate with body size or condition. However, song output during the dawn chorus tended to be positively correlated with T levels. Therefore, if high T levels are costly, song output might be an honest indicator of male quality in blue tits. Finally, we show that plasma levels of T are significantly higher during the night than during the day. This pattern has also been observed in captive non-passerine birds, but its functional significance remains unknown.

Miniaturization of electromagnetic band gap structures for mobile applications

It is well known that interference of the human body affects the performance of the antennas in mobile phone handsets. In this contribution, we investigate the use of miniaturized metallodielectric electromagnetic band gap (MEBG) structures embedded in the case of a mobile handset as a means of decoupling the antenna from the user's hand. The closely coupled MEBG concept is employed to achieve miniaturization of the order of 15:1. Full wave dispersion relations for planar closely coupled MEBG arrays are presented and are validated experimentally. The performance of a prototype handset with an embedded conformal MEBG is assessed experimentally and is compared to a similar prototype without the MEBG. Reduction in the detuning of the antenna because of the human hand by virtue of the MEBG is demonstrated. Moreover, the efficiency of the handset when loaded with a human hand model is shown to improve when the MEBG is in place. The improvements are attributed to the decoupling of the antenna from the user's hand, which is achieved by means of suppressing the fields in the locality of the hand.

Microporation Techniques for Enhanced Delivery of Therapeutic Agents

Perhaps the greatest barrier to development of the field of transmembrane drug delivery is that only a limited number of drugs are amenable to administration by this route. The highly lipophilic nature and barrier function of the uppermost layer of the skin, the stratum corneum, for example, restricts the permeation of hydrophilic, high molecular weight and charged compounds into the systemic circulation. Other membranes in the human body can also present significant barriers to drug permeation. In order to successfully deliver hydrophilic drugs, and macromolecular agents of interest, including peptides, DNA and small interfering RNA, many research groups and pharmaceutical companies Worldwide are focusing on the use of microporation methods and devices. Whilst there are a variety of microporation techniques, including the use of laser, thermal ablation, electroporation, radiofrequency, ultrasound, high pressure jets, and microneedle technology, they share the common goal of enhancing the permeability of a biological membrane through the creation of transient aqueous transport pathways of micron dimensions across that membrane. Once created, these micropores are orders of magnitude larger than molecular dimensions and, therefore, should readily permit the transport of hydrophilic macromolecules. Additionally, microporation devices also enable minimally-invasive sampling and monitoring of biological fluids. This review deals with the innovations relating to microporation-based methods and devices for drug delivery and minimally invasive monitoring, as disclosed in recent patent literature. © 2010 Bentham Science Publishers Ltd.

Adenosine, inflammation and asthma - a review

Adenosine is a ubiquitous molecule present in every cell of the human body. It has a wide range of physiological functions mediated predominantly through specific cell surface adenosine receptors. Adenosine has both pro- and anti-inflammatory effects and acts on inflammatory and resident immune cells and antioxidant enzymes. The elevation of adenosine in the bronchoalveolar lavage (BAL) fluid of asthmatics combined with its bronchoconstrictor effect on the airways in asthmatics has led to increased research into the contribution of adenosine in the pathophysiology of inflammation and asthma. This review looks at the airway response to adenosine and at the interaction of adenosine with mast cells and basophils.

Invader-invader interactions in relation to environmental heterogeneity leads to zonation of two invasive amphipods, Dikerogammarus villosus (Sowinsky) and Gammarus tigrinus Sexton: amphipod pilot species project (AMPIS) report 6

As biological invasions continue, interactions occur not only between invaders and natives, but increasingly new invaders come into contact with previous invaders. Whilst this can lead to species replacements, co-existence may occur, but we lack knowledge of processes driving such patterns. Since environmental heterogeneity can determine species richness and co-existence, the present study examines habitat use and its mediation of the predatory interaction between invasive aquatic amphipods, the Ponto-Caspian Dikerogammarus villosus and the N. American Gammarus tigrinus. In the Dutch Lake IJsselmeer, we found broad segregation of D. villosus and G. tigrinus by habitat type, the former predominating in the boulder zone and the latter in the soft sediment. However, the two species co-exist in the boulder zone, both on the short and longer terms. We used an experimental simulation of habitat heterogeneity and show that both species utilize crevices, different sized holes in a plastic grid, non-randomly. These amphipods appear to optimise the use of holes with respect to their 'C-shape' body size. When placed together, D. villosus adults preyed on G. tigrinus adults and juveniles, while G. tigrinus adults preyed on D. villosus juveniles. Juveniles were also predators and both species were cannibalistic. However, the impact on G. tigrinus of the superior intraguild predator, D. villosus, was significantly reduced where experimental grids were present as compared to absent. This mitigation of intraguild predation between the two species in complex habitats may explain the co-existence of these two invasive species.

Signal residuals and hermit crab displays: flaunt it if you have it!

In animal contests selection should favour information gathering regarding the likely costs and benefits of continued conflict, and displays may provide a means for contestants to gain information about the fighting ability or aggressive intent of competitors. However, there is debate over the reliability of such displays and low levels of deception may occur within otherwise honest signalling systems. Hermit crabs use displays involving the chelipeds during agonistic encounters. We examined how variation in chelae size in relation to body size, a determinant of fighting ability, affects their use in displays and the process and outcome of contests over gastropod shells. In accordance with deceptive use of an otherwise honest signal, we found that contestants with large chelipeds for their body size spent more time performing the cheliped presentation display. Moreover, cheliped residuals and displays influenced the escalation level of encounters. There was a positive association between cheliped displays and the occurrence of 'grappling', but a negative association between displays and the occurrence of shell fights, suggesting that displays may signal aggressive intent and a reluctance to back off or accept the more passive defender role in a fight. Furthermore, the smaller of the two contestants in shell fights had larger cheliped residuals compared to those smaller contestants not involved in shell fights, which is consistent with disrupted opponent assessment. This study adds to mounting evidence that when acting as a signaller, individuals for whom the display exaggerates competitive ability attempt to manipulate opponents, using the display more often. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.