title: Converting predation cues into conservation tools: The effect of light on mouse foraging behaviour

authors: Farnworth, Bridgette

abstract: Prey face a conflict between acquiring energy and avoiding predators and use both direct and indirect cues to assess predation risk. Illumination, an indirect cue, influences nocturnal rodent foraging behaviour. New Zealand holds no native rodent species but has introduced mice (Mus musculus) that severely impair native biodiversity. We used Giving-Up Densities (GUDs) and observations of foraging frequency and duration to assess if artificial light induces risk avoidance behaviour in mice and could limit their activity. We found both captive (wild strain) mice in outdoor pens and wild mice within a pest fenced sanctuary (Maungatautari, New Zealand) displayed avoidance behaviour in response to illumination. In captivity, total foraging effort was similar across lit and unlit pens but mice displayed a strong preference for removing seeds from dark control areas (mean: 15.33 SD: +/-11.64 per 3.5 hours) over illuminated areas (2.00 +/-3.44). Wild mice also removed fewer seeds from illuminated areas (0.42 +/-1.00 per 12 hours) compared to controls (6.67 +/-9.20). Captive mice spent less than 1.0% of available time at illuminated areas, versus 11.3% at controls; visited the lit areas less than control areas (12.00 +/- 9.77 versus 29.00 +/-21.58 visits respectively); and spent less time per visit at illuminated versus control areas (8.17 +/-7.83 versus 44.83 +/-87.52 seconds per visit respectively). Illumination could provide protection at ecologically sensitive sites, damaged exclusion fences awaiting repair, fence terminus zones of peninsula sanctuaries and shipping docks that service offshore islands. We promote the hypothesis that the tendency of mice to avoid illumination could be a useful conservation tool, and advance knowledge of risk assessment and foraging under perceived danger.

text: Converting predation cues into conservation tools: The effect of light on mouse foraging behaviour Prey face a conflict between acquiring energy and avoiding predators and use both direct and indirect cues to assess predation risk. Illumination, an indirect cue, influences nocturnal rodent foraging behaviour. New Zealand holds no native rodent species but has introduced mice (Mus musculus) that severely impair native biodiversity. We used Giving-Up Densities (GUDs) and observations of foraging frequency and duration to assess if artificial light induces risk avoidance behaviour in mice and could limit their activity. We found both captive (wild strain) mice in outdoor pens and wild mice within a pest fenced sanctuary (Maungatautari, New Zealand) displayed avoidance behaviour in response to illumination. In captivity, total foraging effort was similar across lit and unlit pens but mice displayed a strong preference for removing seeds from dark control areas (mean: 15.33 SD: +/-11.64 per 3.5 hours) over illuminated areas (2.00 +/-3.44). Wild mice also removed fewer seeds from illuminated areas (0.42 +/-1.00 per 12 hours) compared to controls (6.67 +/-9.20). Captive mice spent less than 1.0% of available time at illuminated areas, versus 11.3% at controls; visited the lit areas less than control areas (12.00 +/- 9.77 versus 29.00 +/-21.58 visits respectively); and spent less time per visit at illuminated versus control areas (8.17 +/-7.83 versus 44.83 +/-87.52 seconds per visit respectively). Illumination could provide protection at ecologically sensitive sites, damaged exclusion fences awaiting repair, fence terminus zones of peninsula sanctuaries and shipping docks that service offshore islands. We promote the hypothesis that the tendency of mice to avoid illumination could be a useful conservation tool, and advance knowledge of risk assessment and foraging under perceived danger.

year: 2016

title: Ultrasonic Air Leak Detection: An Investigation to Improve Accuracy of Leak Rate Estimation

authors: Wolstencroft, Hamish Roger

subjects: ultrasonic

abstract: A compressed air test rig was designed to develop new procedures and improve the reliability of results that are obtained when conducting a leak survey using an Ultrasonic leak detector such as the UE Systems Ultraprobe.

A test rig was designed that allowed the pressure of air in a compressed air system to be controlled by a regulator. This allowed experiments to be conducted that were able to recreate leak situations in a controlled environment. The pressure of the air through the test rig was measured both at the supply end and at the proximity of the leak site, while the volume flow rate was measured at the supply end of the rig.

A number of leak geometries were examined, with compressed air being passed through open ended tubing and also discs with different leak geometries, some round holes and some rectangular. Initial studies were also carried out on flange leaks and pinpricks and slits in lengths of tubing. These were omitted from the study at this stage to allow further experimentation to be conducted in both areas.

The experimentation was carried out using an Ultraprobe 9000 leak detector which was positioned at a set distance from the leak at a series of angles to the flow. The ultrasound level was measured at each point and compared with the pressure and volume flow rate of the air in the system.

The results showed that the ideal angle to ensure the maximum level of ultrasound is at 30 to the axis of the leak. While the optimum distance for ensuring a consistent level of ultrasound is 150mm from the leak.

The length of any air lines branching from the main distribution network is shown to be an important factor when quantifying the volumetric flow rate of air from an open ended tube or tubing with a significant orifice in it. The pressure drop in a 1m length of tubing was shown to be approximately 50%, and if you consider that often the flow rate being used has been obtained using the outside diameter of the tubing rather than the inside diameter this can become a considerable over estimation of leak rate.

The geometry of a regular shaped orifice, such as a round, or rectangular hole was shown to have little to no effect on the flow rate through it for a constant area. However a coefficient of discharge to account for imperfections in the flow was developed for round and rectangular geometries, these were 0.74 for a round hole and 0.79 for a rectangular hole. These correction factors in tandem with the length effect factor for tubing and the improvements to the measurement procedure, allow a higher degree of accuracy to be obtained when conducting a leak survey.

text: Ultrasonic Air Leak Detection: An Investigation to Improve Accuracy of Leak Rate Estimation A compressed air test rig was designed to develop new procedures and improve the reliability of results that are obtained when conducting a leak survey using an Ultrasonic leak detector such as the UE Systems Ultraprobe.

A test rig was designed that allowed the pressure of air in a compressed air system to be controlled by a regulator. This allowed experiments to be conducted that were able to recreate leak situations in a controlled environment. The pressure of the air through the test rig was measured both at the supply end and at the proximity of the leak site, while the volume flow rate was measured at the supply end of the rig.

A number of leak geometries were examined, with compressed air being passed through open ended tubing and also discs with different leak geometries, some round holes and some rectangular. Initial studies were also carried out on flange leaks and pinpricks and slits in lengths of tubing. These were omitted from the study at this stage to allow further experimentation to be conducted in both areas.

The experimentation was carried out using an Ultraprobe 9000 leak detector which was positioned at a set distance from the leak at a series of angles to the flow. The ultrasound level was measured at each point and compared with the pressure and volume flow rate of the air in the system.

The results showed that the ideal angle to ensure the maximum level of ultrasound is at 30 to the axis of the leak. While the optimum distance for ensuring a consistent level of ultrasound is 150mm from the leak.

The length of any air lines branching from the main distribution network is shown to be an important factor when quantifying the volumetric flow rate of air from an open ended tube or tubing with a significant orifice in it. The pressure drop in a 1m length of tubing was shown to be approximately 50%, and if you consider that often the flow rate being used has been obtained using the outside diameter of the tubing rather than the inside diameter this can become a considerable over estimation of leak rate.

The geometry of a regular shaped orifice, such as a round, or rectangular hole was shown to have little to no effect on the flow rate through it for a constant area. However a coefficient of discharge to account for imperfections in the flow was developed for round and rectangular geometries, these were 0.74 for a round hole and 0.79 for a rectangular hole. These correction factors in tandem with the length effect factor for tubing and the improvements to the measurement procedure, allow a higher degree of accuracy to be obtained when conducting a leak survey.

year: 2008

title: The discovery of gold at Te Aroha and its consequences: January to October 1880

authors: Hart, Philip

abstract: By mid-1880, when there were expectations that gold would be found at Te Aroha, at last Ngati Rahiri permitted prospecting. A government-subsidized prospecting party under Hone Werahiko set out in early August and announced an apparently valuable find one month later. As the discovery was on Ngati Rahiri land, a goldfield could not be declared open immediately, but despite this increasing numbers of prospectors arrived. Newspapers were cautious, not wanting to encourage a rush based on nothing but rumours, some of them extravagant, notably one of finding ore that would produce 200oz to the ton. 
Despite being doubtful about the prospects, officials prepared to proclaim a new goldfield. In late October, good specimens were shown in Thames, encouraging more to leave both there and the Waikato to explore. After the warden inspected the ground where Werahiko had found gold, which was off limits to everyone except the original prospectors, he arranged to have the only test made before the field was opened. Although this gave an uncertain indication of whether the ore was payable, and little real work was being done outside the prospectors’ claim, regulations were devised permitting the proclamation of the new field.

text: The discovery of gold at Te Aroha and its consequences: January to October 1880 By mid-1880, when there were expectations that gold would be found at Te Aroha, at last Ngati Rahiri permitted prospecting. A government-subsidized prospecting party under Hone Werahiko set out in early August and announced an apparently valuable find one month later. As the discovery was on Ngati Rahiri land, a goldfield could not be declared open immediately, but despite this increasing numbers of prospectors arrived. Newspapers were cautious, not wanting to encourage a rush based on nothing but rumours, some of them extravagant, notably one of finding ore that would produce 200oz to the ton. 
Despite being doubtful about the prospects, officials prepared to proclaim a new goldfield. In late October, good specimens were shown in Thames, encouraging more to leave both there and the Waikato to explore. After the warden inspected the ground where Werahiko had found gold, which was off limits to everyone except the original prospectors, he arranged to have the only test made before the field was opened. Although this gave an uncertain indication of whether the ore was payable, and little real work was being done outside the prospectors’ claim, regulations were devised permitting the proclamation of the new field.

year: 2016