2,400 research outputs found
System and process development for selection of high stress tolerance personnel
Process development of system for digital computer processing of psychophysiological data to obtain high stress tolerance personne
Vienna Circle and Logical Analysis of Relativity Theory
In this paper we present some of our school's results in the area of building
up relativity theory (RT) as a hierarchy of theories in the sense of logic. We
use plain first-order logic (FOL) as in the foundation of mathematics (FOM) and
we build on experience gained in FOM.
The main aims of our school are the following: We want to base the theory on
simple, unambiguous axioms with clear meanings. It should be absolutely
understandable for any reader what the axioms say and the reader can decide
about each axiom whether he likes it. The theory should be built up from these
axioms in a straightforward, logical manner. We want to provide an analysis of
the logical structure of the theory. We investigate which axioms are needed for
which predictions of RT. We want to make RT more transparent logically, easier
to understand, easier to change, modular, and easier to teach. We want to
obtain deeper understanding of RT.
Our work can be considered as a case-study showing that the Vienna Circle's
(VC) approach to doing science is workable and fruitful when performed with
using the insights and tools of mathematical logic acquired since its formation
years at the very time of the VC activity. We think that logical positivism was
based on the insight and anticipation of what mathematical logic is capable
when elaborated to some depth. Logical positivism, in great part represented by
VC, influenced and took part in the birth of modern mathematical logic. The
members of VC were brave forerunners and pioneers.Comment: 25 pages, 1 firgure
Comparing theories: the dynamics of changing vocabulary. A case-study in relativity theory
There are several first-order logic (FOL) axiomatizations of special
relativity theory in the literature, all looking essentially different but
claiming to axiomatize the same physical theory. In this paper, we elaborate a
comparison, in the framework of mathematical logic, between these FOL theories
for special relativity. For this comparison, we use a version of mathematical
definability theory in which new entities can also be defined besides new
relations over already available entities. In particular, we build an
interpretation of the reference-frame oriented theory SpecRel into the
observationally oriented Signalling theory of James Ax. This interpretation
provides SpecRel with an operational/experimental semantics. Then we make
precise, "quantitative" comparisons between these two theories via using the
notion of definitional equivalence. This is an application of logic to the
philosophy of science and physics in the spirit of Johan van Benthem's work.Comment: 27 pages, 8 figures. To appear in Springer Book series Trends in
Logi
Expansive actions on uniform spaces and surjunctive maps
We present a uniform version of a result of M. Gromov on the surjunctivity of
maps commuting with expansive group actions and discuss several applications.
We prove in particular that for any group and any field \K, the
space of -marked groups such that the group algebra \K[G] is
stably finite is compact.Comment: 21 page
Twin Paradox and the logical foundation of relativity theory
We study the foundation of space-time theory in the framework of first-order
logic (FOL). Since the foundation of mathematics has been successfully carried
through (via set theory) in FOL, it is not entirely impossible to do the same
for space-time theory (or relativity). First we recall a simple and streamlined
FOL-axiomatization SpecRel of special relativity from the literature. SpecRel
is complete with respect to questions about inertial motion. Then we ask
ourselves whether we can prove usual relativistic properties of accelerated
motion (e.g., clocks in acceleration) in SpecRel. As it turns out, this is
practically equivalent to asking whether SpecRel is strong enough to "handle"
(or treat) accelerated observers. We show that there is a mathematical
principle called induction (IND) coming from real analysis which needs to be
added to SpecRel in order to handle situations involving relativistic
acceleration. We present an extended version AccRel of SpecRel which is strong
enough to handle accelerated motion, in particular, accelerated observers.
Among others, we show that the Twin Paradox becomes provable in AccRel, but it
is not provable without IND.Comment: 24 pages, 6 figure
Scheduled Emergency Trauma Operation : The Green Line Orthopedic Trauma Surgery Process Of Care
Background and Aims: Traditionally, patients requiring an orthopedic emergency operation were admitted to an inpatient ward to await surgery. This often led to congestion of wards and operation rooms while, for less urgent traumas, the time spent waiting for the operation often became unacceptably long. The purpose of this study was to evaluate the flow of patients coded green in a traffic light-based coding process aimed at decreasing the burden on wards and enabling a scheduled emergency operation in Central Finland Hospital. Materials and Methods: Operation urgency was divided into three categories: green (>48 h), yellow (8-48 h), and red (Peer reviewe
A Geometrical Characterization of the Twin Paradox and its Variants
The aim of this paper is to provide a logic-based conceptual analysis of the
twin paradox (TwP) theorem within a first-order logic framework. A geometrical
characterization of TwP and its variants is given. It is shown that TwP is not
logically equivalent to the assumption of the slowing down of moving clocks,
and the lack of TwP is not logically equivalent to the Newtonian assumption of
absolute time. The logical connection between TwP and a symmetry axiom of
special relativity is also studied.Comment: 22 pages, 3 figure
A transient helix in the disordered region of dynein light intermediate chain links the motor to structurally diverse adaptors for cargo transport
All animal cells use the motor cytoplasmic dynein 1 (dynein) to transport diverse cargo toward microtubule minus ends and to organize and position microtubule arrays such as the mitotic spindle. Cargo-specific adaptors engage with dynein to recruit and activate the motor, but the molecular mechanisms remain incompletely understood. Here, we use structural and dynamic nuclear magnetic resonance (NMR) analysis to demonstrate that the C-terminal region of human dynein light intermediate chain 1 (LIC1) is intrinsically disordered and contains two short conserved segments with helical propensity. NMR titration experiments reveal that the first helical segment (helix 1) constitutes the main interaction site for the adaptors Spindly (SPDL1), bicaudal D homolog 2 (BICD2), and Hook homolog 3 (HOOK3). In vitro binding assays show that helix 1, but not helix 2, is essential in both LIC1 and LIC2 for binding to SPDL1, BICD2, HOOK3, RAB-interacting lysosomal protein (RILP), RAB11 family-interacting protein 3 (RAB11FIP3), ninein (NIN), and trafficking kinesin-bind-ing protein 1 (TRAK1). Helix 1 is sufficient to bind RILP, whereas other adaptors require additional segments preceding helix 1 for efficient binding. Point mutations in the C-terminal helix 1 of Caenorhabditis elegans LIC, introduced by genome editing, severely affect development, locomotion, and life span of the animal and disrupt the distribution and transport kinetics of membrane cargo in axons of mechanosensory neurons, identical to what is observed when the entire LIC C-terminal region is deleted. Deletion of the C-terminal helix 2 delays dynein-dependent spindle positioning in the one-cell embryo but overall does not significantly perturb dynein function. We conclude that helix 1 in the intrinsically disordered region of LIC provides a conserved link between dynein and structurally diverse cargo adaptor families that is critical for dynein function in vivo.This work was financed by the Fundo Europeu de Desenvolvimento Regional (FEDER) through the Norte Portugal Regional Operational Programme (NORTE 2020), Portugal 2020 (RG); by the Fundação para a CiĂȘncia e a Tecnologia (FCT)/MinistĂ©rio da CiĂȘncia, Tecnologia e Ensino Superior in the framework of the project NORTE-01-0145-FEDER-030507 (RG); by FCT fellowships IF/01015/2013/CP1157/CT0006 (RG) and SFRH/ BPD/101898/2014 (DJB); by the European Research Council under the European Unionâs Seventh Framework Programme, ERC grant agreement no. ERC-2013-StG-338410-DYNEINOME (RG), and by a start-up package of the University of Colorado (BV). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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