The Aetiology of thyrotoxicosis

Very little of fundamental significance is known about the aetiology of thyrotoxicosis. Heredity may play some part but its importance is in no way clearly defined. The incidence of thyrotoxicosis is world wide, but there is some concentration of toxic goitres in areas where simple goitres are endemic. There is, as far as I know, no satisfactory explanation why it is about 7 times commoner in women than in men, but almost all agree that stress, either physical or mental, tends to precipitate hyperthyroidism, and this is particularly true of emotion. It is natural, therefore, that workers should turn to possible relationships between the thyroid, the central nervous system and the other endocrine glands when considering the aetiology of the thyrotoxic state

Habitat associations of the Coastal Giant Salamander (Dicamptodon Tenebrosus) at its northern range limit

Knowledge of species-environment associations is critical for the management of threatened amphibian populations facing habitat fragmentation and a restricted range. The Coastal Giant Salamander (Dicamptodon tenebrosus) is subject to habitat degradation from logging and human development and is classified as Threatened at its northern range limit in British Columbia, Canada. We examined habitat associations for D. tenebrosus in relation to relative abundance and presence/absence for 32 streams sampled across the approximately 100 km range of the species in British Columbia. Of 12 environmental variables we measured at 100-m stream reaches and the adjacent riparian zone, D. tenebrosus relative abundance was positively associated with stream elevation, forest age, and the percentage of boulders within streams. A higher stream gradient was the best predictor of D. tenebrosus presence within a stream reach, with present sites having a 91% higher gradient than absent sites. When excluding sites with low relative abundance, D. tenebrosus presence was also predicted by greater forest age surrounding streams and higher site elevation. Our study highlights that conservation planning for stream-associated amphibians with patchy distributions may be improved by an understanding of species-specific habitat associations at the stream-reach scale

Fine sediment on leaves : shredder removal of sediment does not enhance fungal colonisation

Inorganic fine sediments are easily carried into streams and rivers from disturbed land. These sediments can affect the stream biota, including detritivorous invertebrates (shredders) and impair ecosystem functions, such as leaf litter decomposition. We hypothesized that fine sediment (kaolin) deposited on leaves would reduce or suppress fungal development, reducing decomposition rates of leaves. Moreover, we predicted that shredders would act as ecosystem engineers by perturbing sediment deposition, reducing its impact on decomposition and fungi. We used a fully crossed experimental design of sediment addition (control, 400 mg L-1) and shredders (none, Gammarus, Potamophylax) in laboratory aquaria. Leaf mass loss, sus- pended solids, microbial respiration, fungal biomass and spore production were measured. Sediment addition had no significant effects on the leaf mass remaining nor on shredders’ consumption rates. However, sediment slightly reduced fungal assemblage richness and the sporulation rate of three fungal species. The presence of shredders sub- stantially increased the resuspension of fine sediments ([300%),resultinginhighersuspendedloads.However,the action of shredders did not have a significant effect on fungal biomass nor on leaf mass loss. Even if shredders did not enhance fungal colonisation, they affected the settle- ment of fine sediment, serving as allogenic engineers. Our study suggests that concentrations of fine sediment of 400 mg L-1 with short exposure times (192 h) can have some effect on leaf decomposition

Priming of leaf litter decomposition by algae seems of minor importance in natural streams during autumn

Allochthonous detritus of terrestrial origin is one of the main energy sources in forested headwater streams, but its poor nutritional quality makes it difficult to use by heterotrophs. It has been suggested that algae growing on this detritus can enhance its nutritional quality and promote decomposition. So far, most evidence of this "priming effect" is derived from laboratory or mesocosm experiments, and its importance under natural conditions is unclear. We measured accrual of algae, phosphorus uptake capacity, and decomposition of poplar leaves in autumn in open-and closed-canopy reaches in 3 forest and 3 agricultural streams. Chlorophyll a abundance did not change significantly with stream type or with canopy cover, although in some agricultural streams it was higher in open than in closed canopy reaches. Canopy cover did not affect either phosphate uptake capacity or microbial decomposition. On the other hand, although there was no effect of canopy cover on invertebrate fragmentation rate, a significant interaction between canopy cover and stream suggests priming occurs at least in some streams. Overall, the results point to a weak or no priming effect of algae on litter decomposition in natural streams during autumnThe research was funded by the Natural Sciences and Engineering Research Council (Canada) and by the Department of Education, Basque Government, grant number IT951-16. The latter department also funded a research stage by Arturo Elosegi in the University of British Columbia (grant number MV-2017-1-0034)

Life History Phenology and Sediment Size Association of the Dragonfly Cordulegaster dorsalis (Odonata: Cordulegastridae) in an Ephemeral Habitat in Southwestern British Columbia

The life cycle of the dragonfly Cordulegaster dorsalis was studied over one year by systematic sampling of larvae in three intermittent headwater streams in southwestern British Columbia. We determined that larvae normally take three years to reach maturity, emerging throughout July and August. There is limited evidence suggesting a split cohort development, with early emergence after two years. Additionally, we tested whether larval instars were distributed randomly or if they occupied different sediment microhabitats. Smaller animals tend to be associated with smaller grained organic sediments, although there was high variation between the streams

Teaching Psychological Principles to Cybersecurity Students

This paper will discuss our observations gained from teaching psychological principles and methods to undergraduate and postgraduate cybersecurity students. We will draw on and extend our previous work encouraging the teaching of psychology in computing and cybersecurity education. We pay special attention to the consideration of characteristics of cybersecurity students in terms of teaching psychology in a way that will be accessible and engaging. We then discuss the development and use of an online training tool which draws on psychology to help educators and companies to raise awareness of cybersecurity risks in students and employees. Finally, we offer some practical suggestions to incorporate psychology into the cybersecurity curriculum

Characterization of an electron conduit between bacteria and the extracellular environment

A number of species of Gram-negative bacteria can use insoluble minerals of Fe(III) and Mn(IV) as extracellular respiratory electron acceptors. In some species of Shewanella, deca-heme electron transfer proteins lie at the extracellular face of the outer membrane (OM), where they can interact with insoluble substrates. To reduce extracellular substrates, these redox proteins must be charged by the inner membrane/periplasmic electron transfer system. Here, we present a spectro-potentiometric characterization of a trans-OM icosa-heme complex, MtrCAB, and demonstrate its capacity to move electrons across a lipid bilayer after incorporation into proteoliposomes. We also show that a stable MtrAB subcomplex can assemble in the absence of MtrC; an MtrBC subcomplex is not assembled in the absence of MtrA; and MtrA is only associated to the membrane in cells when MtrB is present. We propose a model for the modular organization of the MtrCAB complex in which MtrC is an extracellular element that mediates electron transfer to extracellular substrates and MtrB is a trans-OM spanning ß-barrel protein that serves as a sheath, within which MtrA and MtrC exchange electrons. We have identified the MtrAB module in a range of bacterial phyla, suggesting that it is widely used in electron exchange with the extracellular environment