Energy Balance During a Self-Sufficient, Multistage Ultramarathon

Endurance athletes are recommended to maintain energy balance and ensure adequate energy availability (EA) so that endurance performance is not compromised. Purpose: Describe and evaluate the energy balance of an athlete competing in a self-sufficient, multistage ultramarathon (MSU). Methods: A male endurance athlete (age 35 years; height 183.0 cm; body mass 78.4 kg; VO2max 66 ml/kg/min) volunteered to take part in this observational case study prior to competing in the Marathon des Sables (MdS) 2016. The subject self-reported energy intake (EI) by reviewing his dietary plan following each stage. Basal metabolic rate (BMR) was estimated prior to the MdS based on fat-free mass. Distance and moving speed were recorded using a GPS device throughout the race. Exercise energy expenditure (EEE) was calculated using the GPS device algorithm. Total energy expenditure (TEE) was calculated by adding the athlete’s BMR to the recorded EEE. Energy balance was calculated by subtracting EI from TEE. Results: Mean daily EI was 2946 ± 358 kcal and daily EEE was 3006 ± 1030 kcal. This resulted in a total energy deficit of 9609 kcal with a daily energy deficit of 1922 ± 952 kcal/day. The athlete did not report any subjective feelings of hunger at any point during the event. Conclusions: The athlete did not consume enough calories to meet estimated energy requirements, resulting in a negative energy balance and low EA throughout the event. Relying on subjective perception of hunger to modulate energy intake is an ineffective strategy during a MSU

An investigation of some techniques for the localisation of ionizing radiation

The research carried out was on the development and study of position sensitive proportional counters and was initiated by Dr. R.W.P, Drever. The first chapter of this thesis is a discussion of the type of experimental problems which require the spatial distribution of ionizing radiation to be investigated and of the different methods of obtaining position information. The possible advantages of a proportional counter system for the localisation of charged particles and love energy x-rays are pointed out. In the following chapter, the main factors which limit the position resolution of any electrical detector are outlined, with particular emphasis on the effect of the thermal diffusion of the charge carriers in semiconductor counters, proportional counters and spark chambers. The material for these two chapters was taken mainly from the literature, although the application of diffusion theory to the calculation of the position resolution in the different detectors was the work of the author. Chapter III includes a general description of the method of charge division on a resistive electrode for obtaining position information from a counter; and the limitations to position linearity and resolution which result from the use of this method (as reported in the literature) are discussed. The electronic system required for a position sensitive proportional counter is described and the design and development by the author of a high precision ratio circuit for this work is outlined. The next chapter is an account of the experimental measurements of resolution and linearity performed by the author on proportional counters which were sensitive to position in one dimension. The position resolutions for single electrons, alpha particles and x-rays were measured, and the experimental resolution for single electrons is compared with the limitations from gas diffusion theory in Chapter V. The data for this comparison was partly drain from the literature; but one of the methods used for calculating the electron diffusion in a gas mixture was devised by the author. The interpretation of the performance of these detectors, in Chapter V, is also that of the writer. Chapter VI deals with the building and operation of a two dimensional position sensitive proportional counter which uses a new method of obtaining the counter signal - from electrodes placed between the anode and the cathode. This method was proposed by Dr. Drever. The counter frame used for this work had been designed initially by him, but a number of important modifications to it were made by the author. The development of the counter and the investigation of its performance were the entire responsibility of the author. The appendix to this thesis is an account of an attempt to observe proportional counter or Oeiger counter operation in a cylindrical detector filled with liquid hexane. This work was initiated and carried out by the writer

Field tests of a portable MEMS gravimeter

Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5.58 × 10−6 ms−2 . It is then demonstrated that a change in gravitational acceleration of 4.5 × 10−5 ms−2 can be measured as the device is moved between the top and the bottom of a 20.7 m lift shaft with a signal-to-noise ratio (SNR) of 14.25. Finally, the device is demonstrated to be stable in a more harsh environment: a 4.5 × 10−4 ms−2 gravity variation is measured between the top and bottom of a 275-m hill with an SNR of 15.88. These initial field-tests are an important step towards a chip-sized gravity senso

Measurements of the Young’s modulus of hydroxide catalysis bonds, and the effect on thermal noise in ground-based gravitational wave detectors

With the outstanding results from the detection and observation of gravitational waves from coalescing black holes and neutron star inspirals, it is essential that pathways to further improve the sensitivities of the LIGO and VIRGO detectors are explored. There are a number of factors that potentially limit the sensitivities of the detectors. One such factor is thermal noise, a component of which results from the mechanical loss in the bond material between the silica fibre suspensions and the test mass mirrors. To calculate its magnitude, the Young’s modulus of the bond material has to be known with reasonable accuracy. In this paper we present a new combination of ultrasonic technology and Bayesian analysis to measure the Young’s modulus of hydroxide catalysis bonds between fused silica substrates. Using this novel technique, we measure the bond Young’s modulus to be 18.5 ± 2.0 2.3     GPa . We show that by applying this value to thermal noise models of bonded test masses with suitable attachment geometries, a reduction in suspension thermal noise consistent with an overall design sensitivity improvement allows a factor of 5 increase in event rate to be achieved

Construction of rugged, ultrastable optical assemblies with optical component alignment at the few microradian level

A method for constructing quasimonolithic, precision-aligned optical assemblies is presented. Hydroxide-catalysis bonding is used, adapted to allow optimization of component fine alignment prior to the bond setting. We demonstrate the technique by bonding a fused silica mirror substrate to a fused silica baseplate. In-plane component placement at the submicrometer level is achieved, resulting in angular control of a reflected laser beam at the sub-10-μrad level. Within the context of the LISA Pathfinder mission, the technique has been demonstrated as suitable for use in space-flight applications. It is expected that there will also be applications in a wide range of areas where accuracy, stability, and strength of optical assemblies are important

Competitive titration in living sea urchin embryos of regulatory factors required for expression of the CyIIIa actin gene

Previous studies have located some twenty distinct sites within the 2.3 kb 5' regulatory domain of the sea urchin CyIIIa cytoskeletal actin gene, where there occur in vitro high-specificity interactions with nuclear DNA-binding proteins of the embryo. This gene is activated in late cleavage, exclusively in cells of the aboral ectoderm cell lineages. In this study, we investigate the functional importance in vivo of these sites of DNA-protein interaction. Sea urchin eggs were coinjected with a fusion gene construct in which the bacterial chloramphenicol acetyltransferase (CAT) reporter gene is under the control of the entire CyIIIa regulatory domain, together with molar excesses of one of ten nonoverlapping competitor subfragments of this domain, each of which contains one or a few specific site(s) of interaction. The exogenous excess binding sites competitively titrate the available regulatory factors away from the respective sites associated with the CyIIIa.CAT reporter gene. This provides a method for detecting in vivo sites within the regulatory domain that are required for normal levels of expression, without disturbing the structure of the regulatory domain. We thus identify five nonoverlapping regions of the regulatory DNA that apparently function as binding sites for positively acting transcriptional regulatory factors. Competition with a subfragment bearing an octamer site results in embryonic lethality. We find that three other sites display no quantitative competitive interference with CyIIIa.CAT expression, though as shown in the accompanying paper, two of these sites are required for control of spatial expression. We conclude that the complex CyIIIa regulatory domain must assess the state of many distinct and individually necessary interactions in order to properly regulate CyIIIa transcriptional activity in development

Effect of stress and temperature on the optical properties of silicon nitride membranes at 1550 nm

Future gravitational-wave detectors operated at cryogenic temperatures are expected to be limited by thermal noise of the highly reflective mirror coatings. Silicon nitride is an interesting material for such coatings as it shows very low mechanical loss, a property related to low thermal noise, which is known to further decrease under stress. Low optical absorption is also required to maintain the low mirror temperature. Here, we investigate the effect of stress on the optical properties at 1,550 nm of silicon nitride membranes attached to a silicon frame. Our approach includes the measurement of the thermal expansion coefficient and the thermal conductivity of the membranes. The membrane and frame temperatures are varied, and translated into a change in stress using finite element modeling. The resulting product of the optical absorption and thermo-optic coefficient (dn/dT) is measured using photothermal common-path interferometry

Microelectromechanical system gravimeters as a new tool for gravity imaging

A microelectromechanical system (MEMS) gravimeter has been manufactured with a sensitivity of 40 ppb in an integration time of 1 s. This sensor has been used to measure the Earth tides: the elastic deformation of the globe due to tidal forces. No such measurement has been demonstrated before now with a MEMS gravimeter. Since this measurement, the gravimeter has been miniaturized and tested in the field. Measurements of the free-air and Bouguer effects have been demonstrated by monitoring the change in gravitational acceleration measured while going up and down a lift shaft of 20.7 m, and up and down a local hill of 275 m. These tests demonstrate that the device has the potential to be a useful field-portable instrument. The development of an even smaller device is underway, with a total package size similar to that of a smartphone