Transient changes during microwave ablation simulation : a comparative shape analysis

Microwave ablation therapy is a hyperthermic treatment for killing cancerous tumours whereby microwave energy is dispersed into a target tissue region. Modelling can provide a prediction for the outcome of ablation, this paper explores changes in size and shape of temperature and Specific absorption rate fields throughout the course of simulated treatment with different probe concepts. Here, an axisymmetric geometry of a probe embedded within a tissue material is created, solving coupled electromagnetic and bioheat equations using the finite element method, utilizing hp discretisation with the NGSolve library. Results show dynamic changes across all metrics, with different responses from different probe concepts. The sleeve probe yielded the most circular specific absorption rate pattern with circularity of 0.81 initially but suffered the largest reduction throughout ablation. Similarly, reflection coefficients differ drastically from their initial values, with the sleeve probe again experiencing the largest change, suggesting that it is the most sensitive the changes in the tissue dielectric properties in these select probe designs. These collective characteristic observations highlight the need to consider dielectric property changes and probe specific responses during the design cycle.

     

Microelectrode Recording of Tissue Neural Oscillations for a Bionic Olfactory Biosensor

In olfactory research,neural oscillations exhibit excellent temporal regularity,which are functional and necessary at the physiological and cognitive levels.In this paper,we employed a bionic tissue biosensor which treats intact epithelium as sensing element to record the olfactory oscillations extracellularly.After being stimulated by odorant of butanedione,the olfactory receptor neurons generated different kinds of oscillations,which can be described as pulse firing oscillation,transient firing oscillation,superposed firing oscillation,and sustained firing oscillation,according to their temporal appearances respectively.With a time-frequency analysis of sonogram,the oscillations also demonstrated different frequency properties,such as δ,θ,α,β and γ oscillations.The results suggest that the bionic biosensor cooperated with sonogram analysis can well improve the investigation of olfactory oscillations,and provide a novel model for artificial olfaction sensor design.     

Nutrient use by tropical ant communities varies among three extensive elevational gradients: A cross-continental comparison

Aim

Many studies demonstrate that climate limits invertebrates along tropical elevational gradients, but we have only a rudimentary understanding of the role of nutrient limitation and climatic seasonality. Here we examined the relationships between ant community structure, nutrient use and season along three undisturbed elevational gradients, each from a different continent.

Location

Ecuador (South America), Papua New Guinea (PNG: Oceania), Tanzania (Africa).

Time period

2011–2014.

Major taxa studied

Ants.

Methods

Along each of the three gradients, we placed six distinct nutrient types (amino acid, sucrose, sucrose + amino acid, lipid, NaCl, H₂O). In total, we distributed 2370 baits at 38 sites from 203 m to 3972 m. We used generalized linear models to test for the effects of elevation and season on ant species richness and activity and relative nutrient use. We also tested if changes in ant trophic guilds corresponded to changes in the use of particular nutrients.

Results

Both species richness and activity decreased with elevation along each gradient. However, there were significant interaction effects among elevation, region and season, as ant activity in the dry season was higher in Ecuador and Tanzania but lower in PNG. Relative nutrient use varied among regions: ant preference for some nutrients changed with increasing elevation in Ecuador (decrease in lipid use) and Tanzania (decrease in amino acid and H₂O use), while season affected nutrient use in PNG. There were common trends in trophic guilds along the three elevational gradients (e.g. proportional increase of predators), but these did not explain most of the nutrient use patterns.

Main conclusion

While the structure of ant communities changed similarly with elevation, both the seasonal and elevational effects on nutrient use by ants differed between continents. We argue that regional differences in climate and nutrient availability rather than ant functional composition shape nutrient use by ants.     

Isolation and Culture of Dental Epithelial Stem Cells from the Adult Mouse Incisor

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest^1-4, and the mouse incisor provides a model for these processes. This remarkable organ grows continuously throughout the animal''s life and generates all the necessary cell types from active pools of adult stem cells housed in the labial (toward the lip) and lingual (toward the tongue) cervical loop (CL) regions. Only the dental stem cells from the labial CL give rise to ameloblasts that generate enamel, the outer covering of teeth, on the labial surface. This asymmetric enamel formation allows abrasion at the incisor tip, and progenitors and stem cells in the proximal incisor ensure that the dental tissues are constantly replenished. The ability to isolate and grow these progenitor or stem cells in vitro allows their expansion and opens doors to numerous experiments not achievable in vivo, such as high throughput testing of potential stem cell regulatory factors. Here, we describe and demonstrate a reliable and consistent method to culture cells from the labial CL of the mouse incisor.     

Female genital morphology in the secondarily haplogyne spider genus Glenognatha Simon, 1887 (Araneae,Tetragnathidae), with comments on its phylogenetic significance

Female genital morphology of secondarily haplogyne spiders has been poorly studied, hampering the analysis of its possible phylogenetic significance. We conduct a comparative morphological study of 12 species of the secondarily haplogyne spider genus Glenognatha Simon, 1887 using scanning electron microscopy. Representatives of the closely related genera Pachygnatha Sundevall, 1823 and Dyschiriognatha Simon, 1893 were also examined. The female genitalia of Glenognatha, Dyschiriognatha, and Pachygnatha species examined are composed of a spiracle‐shape gonopore, a membranous chamber, a pair of copulatory ducts (CD) leading to spermathecae and a large uterus externus (UE). The most significant variation among Glenognatha species, previously unregistered within Araneoidea, is related with the absence or presence of CD and spermathecae. In addition, several characters as the form and distribution of long stem gland ductules and compartmentalization of the UE may be important for phylogenetic inference at species and generic level. Our results corroborate the close relationship between Dyshiriognatha and Glenognatha. A table with potentially informative female genitalic characters for phylogenetic inference within Glenognatha is provided. Understanding the general structure of the female genitalia in secondarily haplogyne taxa is a crucial step in order to propose characters for phylogenetic inference and to understand its possible functional significance. J. Morphol. 275:1027–1040, 2014. © 2014 Wiley Periodicals, Inc.     

Pear polygalacturonases

The polygalacturonase activity in extracts of ripe D'Anjou pears is due to two enzymes, which can be resolved by chromatography on Sephadex G-100. One