Ingestive behaviour and physiology of the medicinal leech

Ingestion lasts 25 min in Hirudo medicinalis and is characterized by pharyngeal peristalsis which fills the crop. This peristalsis has an initial rate of 2.4 Hz which decays smoothly to 1.2 Hz at termination of ingestion. During ingestion, the leech body wall undergoes peristalsis which appears to aid in filling the crop diverticula. Body peristalsis begins at a rate of 10 min^(-1) and decreases linearly to 2 min^(-1) at termination. The body also undergoes dorsoventral flexions when blood flow is occluded. Blood meal size increases slightly with leech size: 8.4 g for 1-g leeches and 9.7 g for 2-g leeches. However, relative meal size decreases markedly with increasing animal size; from 8.15 times body mass for 1-g to 4.80 times for 2-g leeches. When intact leeches were exposed to micromolar concentrations of serotonin, there was an increase in the rate of pharyngeal peristalsis and the size of the blood meals. Leeches excrete the plasma from their ingested blood meals. Excretion is activated during ingestion, which increases feeding efficiency by increasing the proportion of blood cells in the ingestate. Excretion continues for 4–6 days following ingestion, removing all the remaining plasma from the ingestate. Leech ingestion comprises stereotyped muscular movements, secretion of saliva and excretion of plasma. A strikingly similar feeding physiology is seen in the blood-sucking insect Rhodnius, and we suggest that efficient sanguivory may require the convergent evolution of similar ingestive mechanisms

Rectenna system design

The function of the rectenna in the solar power satellite system is described and the basic design choices based on the desired microwave field concentration and ground clearance requirements are given. One important area of concern, from the EMI point of view, harmonic reradiation and scattering from the rectenna is also designed. An optimization of a rectenna system design to minimize costs was performed. The rectenna cost breakdown for a 56 w installation is given as an example

Understanding temporal rhythms and travel behaviour at destinations: Potential ways to achieve more sustainable travel

This paper analyses the roles played by time in destination-based travel behaviour. It contrasts clock time's linear view of time with fragmented time, instantaneous time, fluid time and flow, time out and the multiple temporalities of tourism experiences. It explores temporal issues in a destination travel context, using qualitative techniques. Data were captured using diary photography, diary-interview method with tourists at a rural destination; their spatial and temporal patterns were captured using a purpose built smartphone app. The analysis revealed three temporal themes influencing travel behaviour: time fluidity; daily and place-related rhythms; and control of time. Three key messages emerge for future sustainable tourist destination-based travel systems. Given the strong desire for temporal fluidity, transport systems should evolve beyond clock-time regimes. Second, temporal forces favour personal modes of transport (car, walk, cycle), especially in rural areas where public transport cannot offer flexibility. Third, the car is personalised and perceived to optimise travel fluidity and speed, but is currently unsustainable. Imaginative initiatives, using new mobile media technology can offer new positive and proactive car travel, utilising spare public and private vehicle capacity. Research is needed to implement mechanisms for individualised space-time scheduling and collective vehicle use strategies. © 2013 Copyright Taylor and Francis Group, LLC

Applications of a Venus thermospheric circulation model

A variety of Pioneer Venus observations suggest a global scale, day-to-night Venus thermospheric circulation. Model studies of the dynamics and energetics of the Venus thermosphere are presented in order to address new driving, mixing and cooling mechanisms for an improved model simulation. The adopted approach was to reexamine the circulation by first using a previous two dimensional code to quantify those physical processes which can be inferred from the Pioneer Venus observations. Specifically, the model was used to perform sensitivity studies to determine the degree to which eddy cooling, eddy or wave drag, eddy diffusion and 15 micrometer radiational cooling are necessary to bring the model temperature and composition fields into agreement with observations. Three EUV heating cases were isolated for study. Global temperature and composition fields in good agreement with Pioneer data were obtained. Large scale horizontal winds 220 m/s were found to be consistent with the observed cold nightside temperatures and dayside bulges of O, CO and CO2. Observed dayside temperatures were obtained by using a 7 to 19% EUV heating efficiency profile. The enhanced 15 micrometer cooling needed for thermal balance is obtained using the best rate coefficient available for atomic O collisional excitation of CO2(0,1,0). Eddy conduction was not found to be a viable cooling mechanism due to the weakened global circulation. The strong 15 micrometer damping and low EUV efficiency imply a very weak dependence of the general circulation to solar cycle variability. The NCAR terrestrial thermospheric general circulation model was adapted for Venus inputs using the above two dimensional model parameters, to give a three dimensional benchmark for future Venus modelling work

Observations of free–free and anomalous microwave emission from LDN 1622 with the 100 m Green Bank Telescope

LDN 1622 has previously been identified as a possible strong source of dust-correlated anomalous microwave emission (AME). Previous observations were limited by resolution meaning that the radio emission could not be compared with current generation high-resolution infrared data from Herschel, Spitzer or Wide-field Infrared Sky Explorer. This paper presents arcminute resolution mapping observations of LDN 1622 at 4.85 and 13.7 GHz using the 100 m Robert C. Byrd Green Bank Telescope. The 4.85 GHz map reveals a corona of free–free emission enclosing LDN 1622 that traces the photodissociation region of the cloud. The brightest peaks of the 4.85 GHz map are found to be within ≈10 per cent agreement with the expected free–free predicted by Southern H-Alpha Sky Survey Atlas H α data of LDN 1622. At 13.7 GHz, the AME flux density was found to be 7.0 ± 1.4 mJy and evidence is presented for a rising spectrum between 13.7 and 31 GHz. The spinning dust model of AME is found to naturally account for the flux seen at 13.7 GHz. Correlations between the diffuse 13.7 GHz emission and the diffuse mid-infrared emission are used to further demonstrate that the emission originating from LDN 1622 at 13.7 GHz is described by the spinning dust model

Synchrotron emission from molecular clouds

Observations of the properties of dense molecular clouds are critical in understanding the process of star-formation. One of the most important, but least understood, is the role of the magnetic fields. We discuss the possibility of using high-resolution, high-sensitivity radio observations to measure the in-situ synchrotron radiation from these molecular clouds. If the cosmic-ray (CR) particles penetrate clouds as expected, then we can measure the B-field strength directly using radio data. So far, this signature has never been detected from the collapsing clouds themselves and would be a unique probe of the magnetic field. Dense cores are typically ∼ 0.05 pc in size, corresponding to ∼arcsec at ∼kpc distances, and flux density estimates are ∼ mJy at 1 GHz. They should be detectable, for example with the Square Kilometre Array

Sixth Sense Transport : Challenges in Supporting Flexible Time Travel

In this paper, we consider the challenges associated with providing a mobile computing system that helps users enjoy a more flexible relationship between time and travel. Current travel plans, especially in Western cultures, are dominated by a strict notion of time. The need to conform to schedules leads to increased pressures for travellers and inefficiencies when these schedules cannot be met. We are interested in exploring the extent to which mobile computing can be used to help travellers relax these schedules and adopt a more opportunistic approach to travel – potentially helping to reduce the environmental, financial and societal costs of modern travel

Deep Halpha imagery of the Eridanus shells

A deep \ha image of interlocking filamentary arcs of nebulosity has been obtained with a wide-field ($\approx$ 30\degree diameter) narrow-band filter camera combined with a CCD as a detector. The resultant mosaic of images, extending to a galactic latitude of 65$^{o}$, has been corrected for field distortions and had galactic coordinates superimposed on it to permit accurate correlations with the most recent H{\sc i} (21 cm), X-ray (0.75 kev) and FIR (IRAS 100 $\mu$m) maps. Furthermore, an upper limit of 0.13 arcsec/yr to the expansion proper motion of the primary 25\degree long nebulous arc has been obtained by comparing a recent \ha image obtained with the San Pedro Martir telescope of its filamentary edge with that on a POSS E plate obtained in 1951. It is concluded that these filamentary arcs are the superimposed images of separate shells (driven by supernova explosions and/or stellar winds) rather than the edges of a single `superbubble' stretching from Barnard's Arc (and the Orion Nebula) to these high galactic latitudes. The proper motion measurement argues against the primary \ha emitting arc being associated with the giant radio loop (Loop 2) except in extraordinary circumstances.Comment: 9 pages, 5 figures, accepted for MNRAS publicatio

Synchrotron radiation from molecular clouds

Observations of the properties of dense molecular clouds are critical in understanding the process of star-formation. One of the most important, but least understood, is the role of the magnetic fields. We discuss the possibility of using high-resolution, high-sensitivity radio observations to measure the in-situ synchrotron radiation from these molecular clouds. If the cosmic-ray particles penetrate clouds as expected, then we can measure the B-field strength directly using radio data. So far, this signature has never been detected from the collapsing clouds themselves and would be a unique probe of the magnetic field. Dense cores are typically ~0.05 pc in size, corresponding to ~arcsec at ~kpc distances, and flux density estimates are ~mJy at 1 GHz. They should be detectable, for example with the Square Kilometre Array.Comment: Proceedings of Conference "Cosmic Rays and their InterStellar Medium Environment", (CRISM-2014), June 24-27, 2014, Montpellier, France. PoS(CRISM2014)03