1,183 research outputs found
Local dimension and finite time prediction in spatiotemporal chaotic systems
We show how a recently introduced statistics [Patil et al, Phys. Rev. Lett.
81 5878 (2001)] provides a direct relationship between dimension and
predictability in spatiotemporal chaotic systems. Regions of low dimension are
identified as having high predictability and vice-versa. This conclusion is
reached by using methods from dynamical systems theory and Bayesian modelling.
We emphasize in this work the consequences for short time forecasting and
examine the relevance for factor analysis. Although we concentrate on coupled
map lattices and coupled nonlinear oscillators for convenience, any other
spatially distributed system could be used instead, such as turbulent fluid
flows.Comment: 5 pagers, 7 EPS figure
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Large losses from little lies: Strategic gender misrepresentation and cooperation
This paper investigates the possibility that a small deceptive act of misrepresenting one's gender to others reduces cooperation in the Golden Balls game, a variant of a prisoner's dilemma game. Compared to treatments where either participants' true genders are revealed to each other in a pair or no information on gender is given, the treatment effects of randomly selecting people to be allowed to misrepresent their gender on defection are positive, sizeable, and statistically significant. Allowing people to misrepresent their gender reduces the average cooperation rate by approximately 10-12 percentage points. While one explanation for the significant treatment effects is that participants who chose to misrepresent their gender in the treatment where they were allowed to do so defect substantially more, the potential of being matched with someone who could be misrepresenting their gender also caused people to defect more than usual as well. On average, individuals who chose to misrepresent their gender are around 32 percentage points more likely to defect than those in the blind and true gender treatments. Further analysis reveals that a large part of the effect is driven by women who misrepresented in same-sex pairs and men who misrepresented in mixed-sex pairs. We conclude that even small short-term opportunities to misrepresent one's gender can potentially be extremely harmful to later human cooperation
Collapse of ringlike structures in 2DEGs under tilted magnetic fields
In the quantum Hall regime, the longitudinal resistivity plotted
as a density--magnetic-field () diagram displays ringlike structures
due to the crossings of two sets of spin split Landau levels from different
subbands [e.g., Zhang \textit{et al.}, Phys. Rev. Lett. \textbf{95}, 216801
(2005)]. For tilted magnetic fields, some of these ringlike structures "shrink"
as the tilt angle is increased and fully collapse at . Here we theoretically investigate the topology of these structures
via a non-interacting model for the 2DEG. We account for the inter Landau-level
coupling induced by the tilted magnetic field via perturbation theory. This
coupling results in anti-crossings of Landau levels with parallel spins. With
the new energy spectrum, we calculate the corresponding diagram of
the density of states (DOS) near the Fermi level. We argue that the DOS
displays the same topology as in the diagram. For the
ring with filling factor , we find that the anti-crossings make it
shrink for increasing tilt angles and collapse at a large enough angle. Using
effective parameters to fit the data, we find a collapsing
angle . Despite this factor-of-two discrepancy with
the experimental data, our model captures the essential mechanism underlying
the ring collapse.Comment: 3 pages, 2 figures; Proceedings of the PASPS V Conference Held in
August 2008 in Foz do Igua\c{c}u, Brazi
Nonlinear Dynamics of the Perceived Pitch of Complex Sounds
We apply results from nonlinear dynamics to an old problem in acoustical
physics: the mechanism of the perception of the pitch of sounds, especially the
sounds known as complex tones that are important for music and speech
intelligibility
Low Bias Negative Differential Resistance in Graphene Nanoribbon Superlattices
We theoretically investigate negative differential resistance (NDR) for
ballistic transport in semiconducting armchair graphene nanoribbon (aGNR)
superlattices (5 to 20 barriers) at low bias voltages V_SD < 500 mV. We combine
the graphene Dirac Hamiltonian with the Landauer-B\"uttiker formalism to
calculate the current I_SD through the system. We find three distinct transport
regimes in which NDR occurs: (i) a "classical" regime for wide layers, through
which the transport across band gaps is strongly suppressed, leading to
alternating regions of nearly unity and zero transmission probabilities as a
function of V_SD due to crossing of band gaps from different layers; (ii) a
quantum regime dominated by superlattice miniband conduction, with current
suppression arising from the misalignment of miniband states with increasing
V_SD; and (iii) a Wannier-Stark ladder regime with current peaks occurring at
the crossings of Wannier-Stark rungs from distinct ladders. We observe NDR at
voltage biases as low as 10 mV with a high current density, making the aGNR
superlattices attractive for device applications.Comment: 6 pages, 4 figure
The September 2004 stench off the southern Malabar coast - A consequence of holococcolithophore bloom
During the third week of September 2004, particularly on 16th and 17th, an unusual and strong stench was reported from the coast at Kollam and Vizhinjam in Kerala (India). Local dailies reported that over 200 children, mostly below 15 years, complained of nausea, chest pain and short periods of breathlessness because of the stench. Many were hospitalized, but were discharged within a couple of hours. A press report stated that the stench was due to dead fish scattered on the beaches and in the water. The report linked the fish death to oxygen depletion and choking of fish gills. Both were reported to be possibly due to proliferation and eventual putrefaction of a fish-toxic alga Cochlodinium polykreikoides. Information was put up on the web that the bloom was caused by Karenia brevis, a toxic dinoflagellate. It was reported that the stench could be felt up to 5 km inland from the coast. On 20 September 2004, the Government of Kerala requested the National Institute of Oceanography (NIO), Goa to determine the cause of the phenomenon. In response, a team from NIO collected near-shore samples of water on 23 and 26 September off Vizhinjam, Shanghumugham and Kollam. During 3-7 October 2004, RV Sagar Sukti, a coastal research vessel of NIO, was used to collect samples in the waters offshore of Vizhinjam, Veli, Kollam in the depth zones of 20-50 m. The water samples collected on 23 and 26 September from the near-shore spots were analysed for various chemical (dissolved oxygen, hydrogen sulphide, nutrients, and salinity) and biological (microbiological, phytoplankton counting and identification) variables. Data from sea-level records at Cochin Port were also examined to learn about the possible evolution of physical conditions before and after the episode described above. In this preliminary report inferences based on analysis of the data is presented
Has the Price of Motherhood Declined Over Time? A Cross-Cohort Comparison of the Motherhood Wage Penalty
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73089/1/j.1741-3737.2003.00597.x.pd
White paper on guidelines concerning enteric nervous system stem cell therapy for enteric neuropathies.
Over the last 20 years, there has been increasing focus on the development of novel stem cell based therapies for the treatment of disorders and diseases affecting the enteric nervous system (ENS) of the gastrointestinal tract (so-called enteric neuropathies). Here, the idea is that ENS progenitor/stem cells could be transplanted into the gut wall to replace the damaged or absent neurons and glia of the ENS. This White Paper sets out experts' views on the commonly used methods and approaches to identify, isolate, purify, expand and optimize ENS stem cells, transplant them into the bowel, and assess transplant success, including restoration of gut function. We also highlight obstacles that must be overcome in order to progress from successful preclinical studies in animal models to ENS stem cell therapies in the clinic
The Liberal Playground: Susan Isaacs, Psychoanalysis and Progressive Education in the Interwar Era
The Cambridge Malting House, an experimental school, serves here as a case study for investigating the tensions within 1920s liberal elites between their desire to abandon some Victorian and Edwardian sets of values in favour of more democratic ones, and at the same time their insistence on preserving themselves as an integral part of the English upper class. Susan Isaacs, the manager of the Malting House, provided the parents â some of whom were the most famous scientists and intellectuals of their age â with an opportunity to fulfil their âfantasyâ of bringing up children in total freedom. In retrospect, however, she deeply criticized those from their milieu for not fully understanding the real socio-cultural implications of their ideological decision to make independence and freedom the core values in their childrenâs education. Thus, 1920s progressive education is a paradigmatic case study of the cultural and ideological inner contradictions within liberal thought in the interwar era. The article also shows how psychoanalysis â which attracted many progressive educators â played a crucial role in providing liberals of all sorts with a new language to articulate their political visions, but, at the same time, explored the limits of the liberal discourse as a whole
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