15,493 research outputs found
Latitudinal trends in human primary activities: characterizing the winter day as a synchronizer
This work analyzes time use surveys from 19 countries (17 European and 2
American) in the middle latitude range from 38{\deg} to 61{\deg} latitude
accounting for 45% of world population in that range. Time marks for primary
activities (sleeping, working and eating) are systematically contrasted against
light/dark conditions related to latitude.
The analysis reveals that winter sunrise is a synchronizer for labor start
time below 54{\deg} where they occur within the winter civil twilight region.
Winter sunset is a source of synchronization for labor end times.
Winter terminator also punctuate meal times in Europe with dinner times
occurring 3h after winter sunset time within a strip of 1h, which is 40%
narrower than variability of dinner local times.
The sleep-wake cycle of laborers in a weekday is shown to be related to
winter sunrise whereas standard population's cycle appears to be irrespective
of latitude.
The significance of the winter terminator depends on two competing factors
average daily labor time (some 7h30m) and winter daytime ---the shortest
photoperiod---. Winter terminator gains significance when shortest photoperiod
roughly matches to daily labor time plus a reasonable lunch break. That is
within a latitude range from 38{\deg} to 54{\deg}.
The significance of winter terminator as a source of synchronization is also
related to contemporary year round time schedules: the shortest photoperiod
represents the worst case scenario the society faces.
Average daily sleep times show little trend with the shortest photoperiod
slope 5min/h for a Pearson coefficient . Average labor time may have
a weak coupling with the shortest photoperiod: slope 29min/h for .Comment: Changes: Descriptive statistics and bivariate correlations added.
Introduction, Results and Discussion largely modified. RevTeX4-1 27 pages, 6
figures, 13 tables. Data from Time Use Surveys, Hetus and Eurosta
Solving Hard Computational Problems Efficiently: Asymptotic Parametric Complexity 3-Coloring Algorithm
Many practical problems in almost all scientific and technological
disciplines have been classified as computationally hard (NP-hard or even
NP-complete). In life sciences, combinatorial optimization problems frequently
arise in molecular biology, e.g., genome sequencing; global alignment of
multiple genomes; identifying siblings or discovery of dysregulated pathways.In
almost all of these problems, there is the need for proving a hypothesis about
certain property of an object that can be present only when it adopts some
particular admissible structure (an NP-certificate) or be absent (no admissible
structure), however, none of the standard approaches can discard the hypothesis
when no solution can be found, since none can provide a proof that there is no
admissible structure. This article presents an algorithm that introduces a
novel type of solution method to "efficiently" solve the graph 3-coloring
problem; an NP-complete problem. The proposed method provides certificates
(proofs) in both cases: present or absent, so it is possible to accept or
reject the hypothesis on the basis of a rigorous proof. It provides exact
solutions and is polynomial-time (i.e., efficient) however parametric. The only
requirement is sufficient computational power, which is controlled by the
parameter . Nevertheless, here it is proved that the
probability of requiring a value of to obtain a solution for a
random graph decreases exponentially: , making
tractable almost all problem instances. Thorough experimental analyses were
performed. The algorithm was tested on random graphs, planar graphs and
4-regular planar graphs. The obtained experimental results are in accordance
with the theoretical expected results.Comment: Working pape
Effective Beta-Functions for Effective Field Theory
We consider the problem of determining the beta-functions for any reduced
effective field theory. Even though not all the Green's functions of a reduced
effective field theory are renormalizable, unlike the full effective field
theory, certain effective beta- functions for the reduced set of couplings may
be calculated without having to introduce vertices in the Feynman rules for
redundant operators. These effective beta-functions suffice to apply the
renormalization group equation to any transition amplitude (i.e., S- matrix
element), thereby rendering reduced effective field theories no more cumbersome
than traditionally renormalizable field theories. These effective
beta-functions may equally be regarded as the running of couplings for a
particular redefinition of the fields.Comment: 13 pages, LaTeX (requires JHEP class). Version 3: additional
references and a slight expansion of Sections 3 and 5. No substantive change
The pattern of growth and poverty reduction in China
China has seen a huge reduction in the incidence of extreme poverty since the economic reforms that started in the late 1970s. Yet, the growth process has been highly uneven across sectors and regions. The paper tests whether the pattern of China´s growth mattered to poverty reduction using a new provincial panel data set constructed for this purpose. The econometric tests support the view that the primary sector (mainly agriculture) has been the main driving force in poverty reduction over the period since 1980. It was the sectoral unevenness in the growth process, rather than its geographic unevenness, that handicapped poverty reduction. Yes, China has had great success in reducing poverty through economic growth, but this happened despite the unevenness in its sectoral pattern of growth. The idea of a trade-off between these sectors in terms of overall progress against poverty in China turns out to be a moot point, given how little evidence there is of any poverty impact of non-primary sector growth, controlling for primary-sector growth. While the non-primary sectors were key drivers of aggregate growth, it was the primary sector that did the heavy lifting against poverty.Rural Poverty Reduction,Achieving Shared Growth,Regional Economic Development,Subnational Economic Development
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