3,227 research outputs found
Realism, Truthmakers, and Language: A study in meta-ontology and the relationship between language and metaphysics
Metaphysics has had a long history of debate over its viability, and substantivity. This thesis explores issues connected to the realism question within the domain of metaphysics, ultimately aiming to defend a realist, substantive metaphysics by responding to so-called deflationary approaches, which have become prominent, and well supported within the recent metametaphysical and metaontological literature.
To this end, I begin by examining the changing nature of the realism question. I argue that characterising realism and anti-realism through theories of truth unduly places epistemology prior to ontology, and is unwarranted in assuming a non-neutrality between theories of truth and positions within the realism debate. I therefore propose a characterisation of realism and anti-realism understood through truthmaking. This produces a suitable working characterisation of realism that will be used within the remainder of this project.
In the second section, I trace the historical influences upon current deflationary approaches to metaphysics, most prominently those of Carnap, and Putnam. I argue that Quine’s supposed attack on Carnap’s anti-metaphysical thought fails, and show how current deflationary thought, most prominently exhibited by Hirsch, came to focus on linguistically derived concerns over the substantivity of metaphysics.
In the third section, I outline a number of issues for the deflationist, and defend the coherency and legitimacy of the unrestricted existential quantifier. Focusing on the linguistic aspect of deflationism, I argue that the conception of language that the deflationist relies upon lacks suitable empirical and theoretical support within linguistics and other related domains. Furthermore, I suggest that linguistic analysis in fact supports the claim that the quantifier carries no inherent restrictions. This restores our ability to suitably posit the unrestricted existential quantifier, as a quantifier wherein the domain is only restricted by metaphysically substantive restrictions. Through this, I argue that metaphysics is a substantive domain of discourse. Lastly, I sketch a positive account of how, under an empirically and theoretically justified conception of language, metaphysics can be coherently held to be a realist, substantive enterprise, contra claims that hold that the nature of language inherently prevents metaphysics being considered to be a substantive domain of discourse
Future vernaculars towards a process-based dwelling ecosystem in pacific atoll nations
Given the already-devastating effects of climate change in Pacific atoll nations, there is an urgency to establish frameworks that support systemic sustainability and resilience within these regions. The evolution of vernacular architecture and community processes needs to be investigated and analyzed. Fundamentally, there is little understanding of: (1) what resilience means, in the context of architecture, building cultures, and localized networks; (2) the intricacies of socioeconomic, cultural, and political fabrics within which projects are pursued; and (3) how to balance soft and rigid approaches to achieving high-performance building and community solutions, while still remaining low impact in the context of localized material loops and building cultures. This paper aims to address and expand upon these points, specifically within the context of the Republic of the Marshall Islands (RMI), in order to formulate a robust, flexible, and self-refining framework for the production of sustainable and resilient housing. It emphasizes sociocultural practices based around housing construction and design to develop culturally supportive housing, local capacity, and recenter localized knowledge systems in housing design. Housing adaptations for remote and urbanized atolls are explored through capacity building and knowledge exchange, collaborating with cultural stakeholders in the RMI. Field surveys of housing across four atolls provide analysis of current building practices, material use, and cultural appropriateness, while a new Dwelling Ecosystem prototype tests new integrations of local knowledge and materials, and scalability
Adjustable microchip ring trap for cold atoms and molecules
We describe the design and function of a circular magnetic waveguide produced
from wires on a microchip for atom interferometry using deBroglie waves. The
guide is a two-dimensional magnetic minimum for trapping weak-field seeking
states of atoms or molecules with a magnetic dipole moment. The design consists
of seven circular wires sharing a common radius. We describe the design, the
time-dependent currents of the wires and show that it is possible to form a
circular waveguide with adjustable height and gradient while minimizing
perturbation resulting from leads or wire crossings. This maximal area geometry
is suited for rotation sensing with atom interferometry via the Sagnac effect
using either cold atoms, molecules and Bose-condensed systems
Oral dosing for antenatal corticosteroids in the Rhesus macaque.
Antenatal corticosteroids (ACS) are standard of care for women at risk of preterm delivery, although choice of drug, dose or route have not been systematically evaluated. Further, ACS are infrequently used in low resource environments where most of the mortality from prematurity occurs. We report proof of principle experiments to test betamethasone-phosphate (Beta-P) or dexamethasone-phosphate (Dex-P) given orally in comparison to the clinical treatment with the intramuscular combination drug beta-phosphate plus beta-acetate in a Rhesus Macaque model. First, we performed pharmacokinetic studies in non-pregnant monkeys to compare blood levels of the steroids using oral dosing with Beta-P, Dex-P and an effective maternal intramuscular dose of the beta-acetate component of the clinical treatment. We then evaluated maternal and fetal blood steroid levels with limited fetal sampling under ultrasound guidance in pregnant macaques. We found that oral Beta is more slowly cleared from plasma than oral Dex. The blood levels of both drugs were lower in maternal plasma of pregnant than in non-pregnant macaques. Using the pharmacokinetic data, we treated groups of 6-8 pregnant monkeys with oral Beta-P, oral Dex-P, or the maternal intramuscular clinical treatment and saline controls and measured pressure-volume curves to assess corticosteroid effects on lung maturation at 5d. Oral Beta-P improved the pressure-volume curves similarly to the clinical treatment. Oral Dex-P gave more variable and nonsignificant responses. We then compared gene expression in the fetal lung, liver and hippocampus between oral Beta-P and the clinical treatment by RNA-sequencing. The transcriptomes were largely similar with small gene expression differences in the lung and liver, and no differences in the hippocampus between the groups. As proof of principle, ACS therapy can be effective using inexpensive and widely available oral drugs. Clinical dosing strategies must carefully consider the pharmacokinetics of oral Beta-P or Dex-P to minimize fetal exposure while achieving the desired treatment responses
Atom chips on direct bonded copper substrates
We present the use of direct bonded copper (DBC) for the straightforward
fabrication of high power atom chips. Atom chips using DBC have several
benefits: excellent copper/substrate adhesion, high purity, thick (> 100
microns) copper layers, high substrate thermal conductivity, high aspect ratio
wires, the potential for rapid (< 8 hr) fabrication, and three dimensional atom
chip structures. Two mask options for DBC atom chip fabrication are presented,
as well as two methods for etching wire patterns into the copper layer. The
wire aspect ratio that optimizes the magnetic field gradient as a function of
power dissipation is determined to be 0.84:1 (height:width). The optimal wire
thickness as a function of magnetic trapping height is also determined. A test
chip, able to support 100 A of current for 2 s without failing, is used to
determine the thermal impedance of the DBC. An assembly using two DBC atom
chips to provide magnetic confinement is also shown.Comment: 8 pages, 5 figure
An HI absorption distance to the black hole candidate X-ray binary MAXI J1535-571
With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored
the black hole candidate X-ray binary MAXI J1535--571 over seven epochs from 21
September to 2 October 2017. Using ASKAP observations, we studied the HI
absorption spectrum from gas clouds along the line-of-sight and thereby
constrained the distance to the source. The maximum negative radial velocities
measured from the HI absorption spectra for MAXI J1535--571 and an
extragalactic source in the same field of view are km s and
km s, respectively. This rules out the far kinematic distance
( kpc), giving a most likely distance of
kpc, with a strong upper limit of the tangent point at kpc.
At our preferred distance, the peak unabsorbed luminosity of MAXI J1535--571
was per cent of the Eddington luminosity, and shows that the soft-to-hard
spectral state transition occurred at the very low luminosity of 1.2 -- 3.4
10 times the Eddington luminosity. Finally, this study
highlights the capabilities of new wide-field radio telescopes to probe
Galactic transient outbursts, by allowing us to observe both a target source
and a background comparison source in a single telescope pointing.Comment: Revised after favorable referee report from MNRAS Letter
Collisional decoherence in trapped atom interferometers that use non-degenerate sources
The coherence time, and thus sensitivity, of trapped atom interferometers
that use non-degenerate gasses are limited by the collisions between the atoms.
An analytic model that describes the effects of collisions between atoms in an
interferometer is developed. It is then applied to an interferometer using a
harmonically trapped non-degenerate atomic gas that is manipulated with a
single set of standing wave laser pulses. The model is used to find the optimal
operating conditions of the interferometer and direct Monte-Carlo simulation of
the interferometer is used to verify the analytic model.Comment: (23 pages, 5 figures
Operational Assessment of Apollo Lunar Surface Extravehicular Activity
Quantifying the operational variability of extravehicular activity (EVA) execution is critical to help design and build future support systems to enable astronauts to monitor and manage operations in deep-space, where ground support operators will no longer be able to react instantly and manage execution deviations due to the significant communication latency. This study quantifies the operational variability exhibited during Apollo 14-17 lunar surface EVA operations to better understand the challenges and natural tendencies of timeline execution and life support system performance involved in surface operations. Each EVA (11 in total) is individually summarized as well as aggregated to provide descriptive trends exhibited throughout the Apollo missions. This work extends previous EVA task analyses by calculating deviations between planned and as-performed timelines as well as examining metabolic rate and consumables usage throughout the execution of each EVA. The intent of this work is to convey the natural variability of EVA operations and to provide operational context for coping with the variability inherent to EVA execution as a means to support future concepts of operations
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