3,813 research outputs found
CW and pulsed electrically detected magnetic resonance spectroscopy at 263 GHz/12 T on operating amorphous silicon solar cells
Here we describe a new high frequency/high field continuous wave and pulsed
electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating
at 263 GHz and resonance fields between 0 and 12 T. Spin dependent transport in
illuminated hydrogenated amorphous silicon p-i-n solar cells at 5 K and 90 K
was studied by in operando 263 GHz CW and pEDMR alongside with complementary
X-band CW EDMR. Benefiting from the superior resolution at 263 GHz, we were
able to better resolve EDMR signals originating from spin dependent hopping and
recombination processes. 5 K EDMR spectra were found to be dominated by
conduction and valence band tale states involved in spin dependent hopping,
with additional contributions from triplet exciton states. 90 K EDMR spectra
could be assigned to spin pair recombination involving conduction band tail
states and dangling bonds as dominating spin dependent transport process, with
additional contributions from valence band tail and triplet exciton states.Comment: 8 pages, 4 figure
Social Preferences and the Efficiency of Bilateral Exchange
Under what conditions do social preferences, such as altruism or a concern for fair outcomes, generate efficient trade? I analyze theoretically a simple bilateral exchange game: Each player sequentially takes an action that reduces his own material payoff but increases the other player’s. Each player’s preferences may depend on both his/her own material payoff and the other player’s. I identify necessary conditions and sufficient conditions on the players’ preferences for the outcome of their interaction to be Pareto efficient. The results have implications for interpreting the rotten kid theorem, gift exchange in the laboratory, and gift exchange in the field
Cost-effectiveness of trastuzumab in the adjuvant treatment of early breast cancer: a model-based analysis of the HERA and FinHer trial
BACKGROUND: Routine adjuvant administration of trastuzumab (T) has been implemented in most centers, but its economic impact has not yet been well examined. METHODS: A Markov model was constructed based on clinical data of the Herceptin Adjuvant (HERA) and the Finland Herceptin (FinHer) trials. Costs from the perspective of a Swiss health care provider were calculated based on resource use. RESULTS: On the basis of HERA data, our model yielded an overall survival rate of 71.8% for the T group versus 62.8% for the control group [risk ratio (RR) = 0.87) after 10 years and 62.9% versus 52.7% (RR = 0.84) after 15 years. Cost-effectiveness resulted in 40505 Euros (EUR) per life years gained (LYG) after 10 years and 19673 EUR per LYG after 15 years. For the FinHer regimen, overall survival after 10 and 15 years resulted in 81.8% versus 66.1% (RR = 0.81) and 73.6% versus 57.0% (RR = 0.77). Costs of 8497 EUR per patient could be saved after 10 years and 9256 EUR after 15 years compared with the control group. CONCLUSION: In a long-term perspective, adjuvant T based on the HERA regimen can be considered cost-effective. The regimen used in the FinHer trial is even cost saving, but estimations are based on a single small tria
Intrauterine light delivery for photodynamic therapy of the human endometrium
Photodynamic therapy is currently being evaluated as a minimally invasive procedure for endometrial ablation not requiring anaesthesia. Light penetration depths at 630, 660 and 690 nm and the optimal configuration of intrauterine light-diffusing fibres were determined in 14 human uteri to assist in the design of a light intrauterine device. Post-menopausal ex-vivo uteri showed a significantly lower light penetration depth than pre-menopausal uteri. With a single central diffusing fibre inserted, the fluence rate measured in the uterine wall at the most remote point of the cavity decreased to 1.1 ± 0.4% of that measured at closest proximity, whereas it decreased to only 40.0 ± 9.0% with three fibres. Distension of the uterine cavity with 2 ml of an optically clear fluid increased the fluence rate at the fundus between the fibres at a depth of 2 mm by a factor of 4. We conclude that in normal-sized pre-menopausal uterine cavities, three diffusing fibres will deliver an optical dose above the photodynamic threshold level at a depth of 4 mm, even in the most remote areas, in <30 min without causing thermal damage. For distorted and elongated cavities, either slight distension of the cavity or the insertion of a fourth diffusing fibre is require
The resurrection of group selection as a theory of human cooperation
Two books edited by members of the MacArthur Norms and Preferences Network (an interdisciplinary group, mainly anthropologists and economists) are reviewed here. These books in large part reflect a renewed interest in group selection
that has occurred among these researchers: they promote the theory that human cooperative behavior evolved via selective processes which favored biological and/or cultural group-level adaptations as opposed to individual-level adaptations. In support of this theory, an impressive collection of cross-cultural data are presented which suggest that participants in experimental economic games often do not behave as self-interested income maximizers; this lack of self-interest is regarded as evidence of group selection. In this review, problems with these data and with the theory are discussed. On the data side, it is argued that even if a behavior seems individually-maladaptive in a game context, there is no reason to believe that it would have been that way in ancestral contexts, since the environments of experimental games do not at all resemble those in which ancestral humans would have interacted cooperatively. And on the theory side, it is argued that it is premature to invoke group selection in order to explain human cooperation, because more parsimonious individual-level theories have not yet been exhausted. In summary, these books represent ambitious interdisciplinary contributions on an important topic, and they include unique and useful data; however, they do not make a convincing case that the evolution of human cooperation required group selection
If cooperation is likely punish mildly: Insights from economic experiments based on the snowdrift game
Punishment may deter antisocial behavior. Yet to punish is costly, and the
costs often do not offset the gains that are due to elevated levels of
cooperation. However, the effectiveness of punishment depends not only on how
costly it is, but also on the circumstances defining the social dilemma. Using
the snowdrift game as the basis, we have conducted a series of economic
experiments to determine whether severe punishment is more effective than mild
punishment. We have observed that severe punishment is not necessarily more
effective, even if the cost of punishment is identical in both cases. The
benefits of severe punishment become evident only under extremely adverse
conditions, when to cooperate is highly improbable in the absence of sanctions.
If cooperation is likely, mild punishment is not less effective and leads to
higher average payoffs, and is thus the much preferred alternative. Presented
results suggest that the positive effects of punishment stem not only from
imposed fines, but may also have a psychological background. Small fines can do
wonders in motivating us to chose cooperation over defection, but without the
paralyzing effect that may be brought about by large fines. The later should be
utilized only when absolutely necessary.Comment: 15 pages, 6 figures; accepted for publication in PLoS ON
Spatial prisoner's dilemma game with volunteering in Newman-Watts small-world networks
A modified spatial prisoner's dilemma game with voluntary participation in
Newman-Watts small-world networks is studied. Some reasonable ingredients are
introduced to the game evolutionary dynamics: each agent in the network is a
pure strategist and can only take one of three strategies (\emph {cooperator},
\emph {defector}, and \emph {loner}); its strategical transformation is
associated with both the number of strategical states and the magnitude of
average profits, which are adopted and acquired by its coplayers in the
previous round of play; a stochastic strategy mutation is applied when it gets
into the trouble of \emph {local commons} that the agent and its neighbors are
in the same state and get the same average payoffs. In the case of very low
temptation to defect, it is found that agents are willing to participate in the
game in typical small-world region and intensive collective oscillations arise
in more random region.Comment: 4 pages, 5 figure
Magnetized Iron Atmospheres for Neutron Stars
Using a Hartree-Fock formalism, we estimate energy levels and photon cross
sections for atomic iron in magnetic fields B ~ 10^13 G. Computing ionization
equilibrium and normal mode opacities with these data, we construct LTE neutron
star model atmospheres at 5.5 < Log(T_eff) < 6.5 and compute emergent spectra.
We examine the dependence of the emergent spectra on T_eff and B. We also show
the spectral variation with the angle between the magnetic field and the
atmosphere normal and describe the significant limb darkening in the X-ray
band. These results are compared with recent detailed computations of neutron
star H model atmospheres in high fields and with low field Fe and H model
atmospheres constructed from detailed opacities. The large spectral differences
for different surface compositions may be discernible with present X-ray data;
we also note improvements needed to allow comparison of Fe models with high
quality spectra.Comment: 18 pages with 5 eps figures, accepted for publication in ApJ Replaced
due to clerical error only: one more author, no new conten
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