RF communication between surface and underwater robotic swarms

In order for underwater robots to communicate with land and air based robots on an equal basis, high speed communications is required. If the robots are not to be tethered then wireless communications is the only possibility. Sonar communications is too slow. Unfortunately radio waves are rapidly attenuated under water due to phenomena such as skin depth. These experiments attempt to extend the range of underwater radio communications.

Paleobiogeographical extinction patterns of Permian brachiopods in the Asian-western Pacific region

Spatial and temporal variations in biological diversity are critical in understanding the role of biogeographical regulation (if any) on mass extinctions. An analysis based on a latest database of the stratigraphic ranges of 89 Permian brachiopod families, 422 genera, and 2059 species within the Boreal, Paleoequatorial, and Gondwanan Realms in the Asian–western Pacific region suggests two discrete mass extinctions, each possibly with different causes. Using species/family rarefaction analysis, we constructed diversity curves for late Artinskian–Kungurian, Roadian–Wordian, Capitanian, and Wuchiapingian intervals for filtering out uneven sampling intensities. The end-Changhsingian (latest Permian) extinction eliminated 87–90% of genera and 94–96% of species of Brachiopoda. The timing of the end-Changhsingian extinction of brachiopods in the carbonate settings of South China and southern Tibet indicates that brachiopods suffered a rapid extinction within a short interval just below the Permian/Triassic boundary.

In comparison, the end-Guadalupian/late Guadalupian extinction is less profound and varies temporally in different realms. Brachiopods in the western Pacific sector of the Boreal Realm nearly disappeared by the end-Guadalupian but experienced a relatively long-term press extinction spanning the entire Guadalupian in the Gondwanan Realm. The end-Guadalupian brachiopod diversity fall is not well reflected at the timescale used here in the Paleoequatorial Realm because the life-depleted early Wuchiapingian was overlapped by a rapid radiation phase in the late Wuchiapingian. The Guadalupian fall appears to be related to the dramatic reduction of habitat area for the brachiopods, which itself is associated with the withdrawal of seawater from continental Pangea and the closure of the Sino-Mongolian seaway by the and-Guadalupian.

Determinants of local abundance in a major radiation of Australian passerines (Aves: Meliphagoidea)

Aim  To identify the factors that contribute to variation in abundance (population density), and to investigate whether habitat breadth and diet breadth predict macroecological patterns in a suborder of passerine birds (Meliphagoidea).
Location  Australia (including Tasmania).
Methods  Mean abundance data were collated from site surveys of bird abundance (the Australian Bird Count); range size and latitudinal position data from published distribution maps; and body mass and diet breadth information from published accounts. A diversity index of habitats used (habitat breadth) was calculated from the bird census data. We used bivariate correlation and multiple regression techniques, employing two phylogenetic comparative methods: phylogenetic generalized least squares and independent contrasts.

Results  Body mass and latitude were the only strong predictors of abundance, with larger-bodied and lower-latitude species existing at lower densities. Together, however, body mass and latitude explained only 11.1% of the variation in mean abundance. Range size and habitat breadth were positively correlated, as were diet breadth and body mass. However, neither range size, nor habitat breadth and diet breadth, explained patterns in abundance either directly or indirectly.
Main conclusions  Levels of abundance (population density) in meliphagoid birds are most closely linked to body mass and latitudinal position, but not range size. As with many other macroecological analyses, we find little evidence for aspects of niche breadth having an effect on patterns of abundance. We hypothesize that evolutionary age may also have a determining effect on why species tend to be rarer (less abundant) in the tropics.

Design and analysis of an antenna for wireless energy harvesting in head-mountable DBS device

This paper presents design and simulation of a circular meander dipole antenna at the industrial, scientific, and medical band of 915 MHz for energy scavenging in a passive head-mountable deep brain stimulation device. The interaction of the proposed antenna with a rat body is modeled and discussed. In the antenna, the radiating layer is meandered, and a FR-4 substrate is used to limit the radius and height of the antenna to 14 mm and 1.60 mm, respectively. The resonance frequency of the designed antenna is 915 MHz and the bandwidth of 15 MHz at a return loss of -10 dB in free space. To model the interaction of the antenna with a rat body, two aspects including functional and biological are considered. The functional aspect includes input impedance, resonance frequency, gain pattern, radiation efficiency of the antenna, and the biological aspect involves electric field distribution, and SAR value. A complete rat model is used in the finite difference time domain based EM simulation software XFdtd. The simulated results demonstrate that the specific absorption rate distributions occur within the skull in the rat model, and their values are higher than the standard regulated values for the antenna receiving power of 1W.

Design and analysis of an antenna for batteryless transcranial direct current stimulation devices

The purpose of this study is to design a low-cost planar Archimedean dipole antenna for batteryless transcranial direct current stimulation devices. The antenna parameters including resonance frequency, radiation efficiency, radiation pattern, and gain are simulated using finite difference time domain based electromagnetic simulation software XFdtd. The proposed antenna is simulated with low-cost FR4 PCB substrate of thickness of 1.6 mm. The antenna is designed with half wavelength of resonant frequency and fed with a matching line. The target frequency band is the industrial, scientific and medical (ISM) band of 915 MHz which is in the simulated band width of 31 MHz (903-934MHz). Moreover, since the bio-effect of specific absorption rate by radio frequency electromagnetic wave for power harvesting is an important concern, we try to find out the safety limit. Thus a quantitative analysis of distributions of electric field and power absorption in anatomical human head model by the far field radio frequency energy received by our designed antenna has been presented.

Insights into the evolution of a cryptic radiation of bats: dispersal and ecological radiation of Malagasy Miniopterus (Chiroptera: Miniopteridae)

The past decade has seen a proliferation of new species of Miniopterus bats (family Miniopteridae) recognized from Madagascar and the neighboring Comoros archipelago. The interspecific relationships of these taxa, their colonization history, and the evolution of this presumed adaptive radiation have not been sufficiently explored. Using the mitochondrial cytochrome-b gene, we present a phylogeny of the Malagasy members of this widespread Old World genus, based on 218 sequences, of which 82 are new and 136 derived from previous studies. Phylogenetic analyses recovered 18 clades, which divide into five primary lineages: (1) M. griveaudi; (2) M. mahafaliensis, M. sororculus and X3; (3) M. majori, M. gleni and M. griffithsi; (4) M. brachytragos; M. aelleniA, and M. aelleniB; and (5) M. manavi and M. petersoni recovered as sister species, which were in turn linked to a group comprising M. egeri and five genetically distinct populations referred to herein as P3, P4, P5, P6 and P7. Beast analysis indicated that the initial divergence within the Malagasy Miniopterus radiation took place 4.5 Myr; most species diverged between 4 and 2.5 Myr, and a secondary period was between 1.25 and 1 Myr. DNA K2P-distances between recognized taxa ranged from 12.9% to 2.5% and intraspecific variation was less than 1.8%. Of the 18 identified clades, Latin binomials are only associated with 11, which indicates much greater differentiation than currently recognized for Malagasy Miniopterus. These data are placed in a context of the dispersal history of this genus on the island and patterns of ecological diversity.

Patterns of care in adult medulloblastoma: results of an international online survey

The literature on medulloblastoma in adults is generally limited to case reports and retrospective series, and there is no accepted standard of care. The Cooperative Trials Group for Neuro-Oncology (COGNO) sought to determine the range and consistency of clinicians’ approaches to management as a basis for future trials. We aimed to identify current treatment strategies for adult medulloblastoma through an online survey launched at the 2012 Society of Neuro-Oncology meeting and by email invitation. Clinicians who had treated at least one adult patient with medulloblastoma, primitive neuroectodermal tumor (PNET), or pineoblastoma in the preceding year were asked about their most recent patient and invited to discuss their approach to a typical clinical scenario. Between November 2012 and January 2013, 45 clinicians (11 medical oncologists, 8 radiation oncologists, 5 pediatric oncologists, and 21 others) from Australia (24), United States (3), Europe (4) and other countries (14) completed the survey. Responding clinicians had treated 54 cases in the past 12 months. The most common histological type was medulloblastoma (64 %), then PNET (20 %). Most patients were male (68 %), and had high-risk disease (65 %). Complete surgical resection in 56 and 32 % had molecular testing. Radiotherapy was predominantly cranio-spinal (92 %) and given mostly post-resection (80 %). Combination chemotherapy was more common than single-agent chemotherapy. The choice of chemotherapy varied considerably. There is substantial variation in the treatment of adult medulloblastoma, most pronounced in the choice of chemotherapeutic agents, highlighting the need for further collaborative research to guide evidence-based treatment strategies.