The performance of Group Diffie-Hellman paradigms: a software framework and analysis

A mobile computing environment typically involves groups of small, low-power devices interconnected through a mobile and dynamic network. Attempts to secure communication over these “ad-hoc” networks must be scalable to conserve the minimal resources of mobile devices as network sizes grow. In this project, the scalability of differing Group Diffie-Hellman security key generation implementations is examined. In theory, the implementation utilizing a data structure with the lowest theoretical run-time complexity for building the Diffie-Hellman group should prove the most scalable experimentally. A common modular framework was implemented to support generic Group Diffie-Hellman key agreement implementations abstracted from the underlying data structure and traversal mechanism. For comparison, linear, tree-based, and hypercubic Group Diffie-Hellman topologies were implemented and tested. Studies were conducted upon the results to compare the experimental scalability of each implementation to the other implementations as well as the theoretic predictions. The results indicate that the benefits of implementations with low theoretic-complexity are rarely experienced in smaller networks (less than 100 nodes,) and conversely implementations with high theoretic-complexities become unsuitable in larger networks (more than 100 nodes.) These experimental results match the theoretical predictions based on the mathematical properties of each implementation. Since mobile ad-hoc networks are typically small, less efficient, less complex implementations of Group Diffie-Hellman key agreement will suit most needs, however larger networks will require more efficient implementations

Mortality of Deer Mice, Peromyscus maniculatus, in Wire Mesh Live-Traps: A Cautionary Note

Live-capture of animals occasionally results in the death of some individuals. Here, we report upon an unusual occurrence of trap-related mortality observed in Deer Mice (Peromyscus maniculatus) captured in wire mesh live-traps during field sampling in southeastern Yukon. Eight of 85 marked individuals (9.4%) were found with their snouts caught in the wire mesh of our live-traps; four of these individuals were found dead. We suggest a modification to Ugglan live-traps that would likely decrease such incidents

The effect of short high intensity intermitent training on pain tolerance and self-paced cycling performance

Introduction Pain tolerance has been identified as a potential factor attributable to an athlete’s success. Previous studies have reported that high intensity intermittent training (HIIT) can increase pain tolerance and exercise capacity. However, it is unclear if short HIIT programs are effective at increasing pain tolerance and self-paced exercise performance. Consequently, we investigated the effect of a short HIIT intervention on pain tolerance and 5 km time trial (TT) cycling performance. Methods Participants (n=18) were randomly assigned and completed either three (Ex-1; n=9) or six HIIT sessions (Ex-2; n=9). HIIT involved participants cycling at RPE=15 (6x5mins interspersed by 1mins recovery). Participant’s pain catastrophizing (PCS), anxiety (PASS-20), ischemic pain tolerance test and 5 km TT performance responses were assessed at baseline and three or six HIIT sessions Results No changes in power output, heart rate or RPE were observed across subsequent HIIT sessions. Pain tolerance and threshold remained unchanged after HIIT. Participant’s PASS responses remained unchanged after HIIT but PCS responses did decrease following HIIT (p=0.002, d=0.56) with no difference between groups. 5 km TT performance remained unchanged although HR decreased after HIIT with no difference between groups (p=0.031, d=0.27). Conclusion Self-paced HIIT was ineffective at increase pain tolerance and cycling time trial performance. This is likely due to the current protocols inefficiency to get participants to exercise to their tolerance and not eliciting the necessary metabolic demands to promote aerobic physiological adaptations respectively. Therefore, future research should consider this and design self-paced HIIT protocols that do not compromise training intensity. Furthermore, research focusing on other psychological measures (e.g. self-efficacy and pain management strategies) should also be considered when assessing the effect of any exercise training on pain tolerance to better understand why any changes in pain tolerance occur

Early use of mineralocorticoid receptor antagonists in ST-elevation myocardial infarction: is it ever too early?

No abstract available

Lineaaristen geokemiallisten trendien mallinnus Magmakammiosimulaattorilla: esimerkkitutkimus Jindabyne-graniiteista, Lachlan Fold Belt, Australia

Understanding the origins of major and trace element variations and the isotopic character of granite samples in terms of sources and magmatic processes is, arguably, the core of granite petrology. It is central to attempts to place these rocks in the context of broader geologic processes and continent evolution. For the granites of the Lachlan and New England Fold Belts (LFB and NEFB) of Australia there has been great debate between competing petrogenetic models. The open-system view is that the isotopic variability and within-suite compositional trends can be accounted for by magma mixing, assimilation and fractional crystallisation (FC). In contrast, the restite unmixing model views the isotope compositions of diverse granites as a feature inherited from individual protoliths that underwent partial melting to produce magmas entraining varying proportions of residual material in a felsic melt. Reconciling all aspects of the geochemical data in a mixing model is contingent on a plausible fractionation regime to produce the observed consistently linear (or near-linear) trends on Harker diagrams; however, published FC models lack phase equilibria constraints on the liquidus assemblage and do not account for the likely changes in trace element partitioning across the modelled compositional range. The Magma Chamber Simulator (MCS) can be used to model fractional crystallisation alone (FC) or with assimilation (AFC), constraining phase equilibria and accounting for the thermal budget. Here, this tool was used to conduct a case study of the I-type Jindabyne Suite of granites from the LFB, testing whether thermodynamically feasible geochemical trends matching the observed linear variations can arise through FC (with or without assimilation of supracrustal material). The results of 112 MCS models show: (1) that major element liquid lines of descent (LLDs) may be sensibly linear over limited compositional ranges, (2) that the involvement of assimilation extends the range in which trends are relatively simple and near-linear, and (3) that, despite these observations, neither FC nor AFC are able to correctly reproduce the geochemical evolution of the I-type Jindabyne Suite granitoids as an LLD (contrary to existing models)—instead, these processes persistently produce curved and kinked trends. The output of these simulations were further refined to explore models in which: (1) crystal-bearing magmas evolve via FC or AFC (with chemical isolation assumed to be achieved through crystal zoning) and undergo varying degrees of melt-crystal segregation at different stages to produce the sample compositions, and (2) in situ crystallisation occurs via FC within the crystallisation zone, driving the evolution of a liquid resident magma, which the samples represent. These models are able to reproduce the Jindabyne Suite trends reasonably well. The modelling implies that FC, or some variant thereof, is a viable explanation for the linear trends in Jindabyne; however, tendency for grossly non-linear LLDs highlights that it should not be assumed that FC can generally explain linear trends in granites without careful modelling such as shown here.Peer reviewe

Long-distance Movement of a Dispersing Deer Mouse, Peromyscus maniculatus, in the Boreal Forest

We report an apparent long-distance, non-homing movement of 3044 ± 60 m made by a dispersing subadult male Deer Mouse, Peromyscus maniculatus, in southeastern Yukon. Our observation is nearly twice the maximum distance previously recorded for non-homing Deer Mice, and apparently the longest dispersal movement recorded for this species