bluuebunny/crossref_metadata_2025 huggingface dataset:
Band structure and the optical gain of GaInNAs/GaAs quantum wells modeled within 10-band and 8-band kp model
Authors: Gladysiewicz M. , Kudrawiec R. , Miloszewski J. M. , Weetman P. , Misiewicz J. , Wartak M. S.
Published: February 2013

The band structure and optical gain have been calculated for GaInNAs/GaAs quantum wells (QWs) with various nitrogen concentrations within the 10-band and 8-band kp models. Two approaches to calculate optical properties of GaInNAs/GaAs QWs have been compared and discussed in the context of available material parameters for dilute nitrides and the conduction band nonparabolicity due to the band anti-crossing (BAC) interaction between the N-related resonant level and the conduction band of a host material. It has been clearly shown that this nonparabolicity can be neglected in optical gain calculations since the dispersion of conduction band up to the Femi level is very close to parabolic for carrier concentrations typical for laser operation, i.e., 5 × 1018 cm−3. This means that the 8-band kp model when used to calculate the optical gain is very realistic and much easier to apply in QWs containing new dilute nitrides for which the BAC parameters are unknown. In such an approach, the energy gap and electron effective mass for N-containing materials are needed, instead of BAC parameters. These parameters are available experimentally much easier than BAC parameters.
Deformation of vortex patches by boundaries
Authors: Crosby A. , Johnson E. R. , Morrison P. J.
Published: February 2013

The deformation of two-dimensional vortex patches in the vicinity of fluid boundaries is investigated. The presence of a boundary causes an initially circular patch of uniform vorticity to deform. Sufficiently far away from the boundary, the deformed shape is well approximated by an ellipse. This leading order elliptical deformation is investigated via the elliptic moment model of Melander, Zabusky, and Styczek [J. Fluid Mech. 167, 95 (1986)10.1017/S0022112086002744]. When the boundary is straight, the centre of the elliptic patch remains at a constant distance from the boundary, and the motion is integrable. Furthermore, since the straining flow acting on the patch is constant in time, the problem is that of an elliptic vortex patch in constant strain, which was analysed by Kida [J. Phys. Soc. Jpn. 50, 3517 (1981)10.1143/JPSJ.50.3517]. For more complicated boundary shapes, such as a square corner, the motion is no longer integrable. Instead, there is an adiabatic invariant for the motion. This adiabatic invariant arises due to the separation in times scales between the relatively rapid time scale associated with the rotation of the patch and the slower time scale associated with the self-advection of the patch along the boundary. The interaction of a vortex patch with a circular island is also considered. Without a background flow, the conservation of angular impulse implies that the motion is again integrable. The addition of an irrotational flow past the island can drive the patch towards the boundary, leading to the possibility of large deformations and breakup.
Viscoelastic characterization of low-velocity impact of a solid ball on an agar gel
Authors: Ara K. , Katsuragi H.
Published: February 2013

A viscoelastic characterization method using low-velocity impact is experimentally studied. A steel ball is dropped from a certain height and impacts on an agar gel target with 1–4 m/s velocity. The motion of the impactor ball is captured by a high-speed camera. Instantaneous penetration depth, velocity, and acceleration of the impactor are computed from the high-speed video data. The obtained kinematic data are analyzed in terms of the equation of motion of the impactor. Specifically, we compute the impact viscosity and impact elasticity, assuming a simple impact drag force model. The impact drag force model consists of a linear viscous term, a linear elastic term, and a constant term. From the estimated impact viscosity, we confirm that the Reynolds number is relatively low (less than 10). This low Reynolds number is consistent with the simple linear viscous assumption. From the estimated impact elasticity, we can calculate the speed of sound and the strength of target agar gel. In order to examine the velocity dependence of the elasticity, we also perform very slow (less than 0.1 mm/s) penetration tests using the same agar gel samples. The comparison between impact elasticity and slow penetration elasticity reveals the weak velocity strengthening of agar gel.
Propagation and dispersion of whistler waves generated by fast reconnection onset
Authors: Singh Nagendra
Published: February 2013

The role of whistler mode during the onset of magnetic reconnection (MR) has been widely suggested, but the manifestations of its highly dispersive and anisotropic propagation properties in reconnection events remain largely unclear. Comparing results from a recently developed theoretical model for reconnection in terms of whistler's dispersive behavior with those reported from laboratory experiments on fast spontaneous magnetic reconnection, we demonstrate that the onset of fast reconnection in electron current layers (ECLs) emits whistler wave packets. The time scale of the explosively fast reconnection events are inversely related to the whistler mode frequencies at the lower end of the whistler frequency band. The wave packets in this frequency band have a characteristic angular dispersion, which marks the initial opening of the reconnection exhaust angle. The multidimensional propagation of the whistler for the reconnection with a strong guide magnetic field is investigated, showing that the measured propagation velocities of the reconnection electric field along the guide field in the Versatile Toroidal Facility at MIT quantitatively compare with the group velocities of the whistler wave packets. The whistler mode dispersive properties measured in laboratory experiments without a guide magnetic field in the magnetic reconnection experiments at Princeton also compare well with the theoretically predicted dispersion of the wave packets depending on the ECL width. Fast normalized reconnection rates extending to ∼0.35 at the MR onset in thin ECLs imply whistler wave propagation away from the onset location. We also present evidences for the whistler wave packets being emitted from reconnection diffusion region as seen in simulations and satellite observations.
Insulation degradation behavior of multilayer ceramic capacitors clarified by Kelvin probe force microscopy under ultra-high vacuum
Authors: Suzuki Keigo , Okamoto Takafumi , Kondo Hiroyuki , Tanaka Nobuhiko , Ando Akira
Published: February 2013

We investigated surface potential images on the cross section of degraded multilayer ceramic capacitors (MLCCs) by Kelvin probe force microscopy measured under a dc bias voltage in ultra-high vacuum. A highly accelerated lifetime test (HALT) was conducted to obtain degraded MLCCs. The high energy resolution of the present measurement allows us to observe the step-like voltage drops on dielectric layers of as-fired MLCCs. The step-like voltage drops disappear on the dielectric layers of degraded MLCCs, indicating that the resistance at grain boundaries declines with the progress of insulation degradation. Furthermore, the electric field concentrations near the electrodes are clearly observed under forward and backward bias. The discussion based on energy band diagrams suggests that the electric field concentrations near electrodes are attributable to energy barrier formed at the interface between electrode and dielectrics. In particular, the electric field concentration at cathode in HALT measured under backward bias is much higher than that at anode in HALT measured under forward bias. This implies that oxygen vacancies accumulated during HALT cause band bending near the cathode in HALT. We propose that the initial decline of resistance at grain boundaries and following electric-field concentrations at anode in HALT is essential to the insulation degradation on dielectric layers of MLCCs under dc bias voltage.
Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate
Authors: He Z.-H. , Thomas A. G. R. , Beaurepaire B. , Nees J. A. , Hou B. , Malka V. , Krushelnick K. , Faure J.
Published: February 2013

We show that electron bunches in the 50–100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.
Impact of reduced dimensionality on the magnetic and magnetocaloric response of La0.7Ca0.3MnO3
Authors: Lampen P. , Bingham N. S. , Phan M. H. , Kim H. , Osofsky M. , Piqué A. , Phan T. L. , Yu S. C. , Srikanth H.
Published: February 2013

Understanding the impact of reduced dimensionality on the magnetic and magnetocaloric responses of a material is vital in incorporating it as an active magnetic refrigerant in cooling devices. By contrasting the magnetic and magnetocaloric behaviors of bulk polycrystalline, sol-gel derived nanocrystalline, and pulsed laser deposited thin film forms of the La0.7Ca0.3MnO3 system, we show that reducing the dimensionality of a ferromagnetic material tends to broaden and shift the paramagnetic to ferromagnetic transition to lower temperatures, while decreasing the saturation magnetization and the magnitude of the magnetic entropy change. Relative to its bulk counterpart, a pronounced broadening of the magnetic entropy change peak in the thin film leads to enhanced refrigerant capacity—an important figure-of-merit for active magnetic refrigeration technology. With reduced dimensionality, universal curves based on re-scaled entropy change curves tend toward collapse, indicating a weakening of the first order nature of the transition in the nanocrystalline samples and a crossover to second order in the thin film.
Pressure-induced phase transformation of In2Se3
Authors: Rasmussen Anya M. , Teklemichael Samuel T. , Mafi Elham , Gu Yi , McCluskey Matthew D.
Published: February 2013

In2Se3 has potential as a phase-change material for memory applications. Understanding its phase diagram is important to achieve controlled switching between phases. Using x-ray diffraction and a diamond-anvil cell, the pressure-dependent structural properties of In2Se3 powder were studied at room temperature. α-In2Se3 transforms into the β phase at 0.7 GPa, an order of magnitude lower than phase-transition critical pressures in typical semiconductors. The β phase persists upon decompression to ambient pressure. Raman spectroscopy experiments confirm this result. The bulk moduli are reported and the c/a ratio for the β phase is shown to have a highly nonlinear dependence on pressure.
Low-threshold and quasi-single-mode random laser within a submicrometer-sized ZnO spherical particle film
Authors: Fujiwara Hideki , Niyuki Ryo , Ishikawa Yoshie , Koshizaki Naoto , Tsuji Takeshi , Sasaki Keiji
Published: February 2013

An unique random laser exhibiting quasi-single-mode and low lasing threshold is developed by a homogenized submicrometer-sized zinc oxide particle film dispersed with intentionally introduced polymer particles as point defects. Such unique random lasing is dominantly initiated at the defect sites, although multi-mode peaks with a collapsed broad emission spectrum are observed at the defect-free sites as in the conventional random lasers. Thus our proposed simple structure can possibly provide the controllability of lasing properties even in random structures.
Polarization of the edge emission from Ag/InGaAsP Schottky plasmonic diode
Authors: Wang C. , Qu H. J. , Chen W. X. , Ran G. Z. , Yu H. Y. , Niu B. , Pan J. Q. , Wang W.
Published: February 2013

Electrical plasmonic sources with compact sizes are a fundamental component in plasmonics. Here, we report a simple plasmonic diode having an Ag/InGaAsP quantum well Schottky structure. The polarization ratio (TM:TE) of the edge-emission photoluminescence for the quantum wells is about 2:1 and increases to about 3:1 after covered by Ag. As contrast, the electroluminescence polarization ratio exceeds 10:1 at a low current, indicating a high plasmon generation efficiency but drops gradually as current increasing; simultaneously, the peak wavelength red shifts evidently, which are attributed to the recombination zone shift and quantum confinement Stark effect.
Transport of perpendicular spin in a semiconductor channel via a fully electrical method
Authors: Bae Joohyung , Kim Kyung-Ho , Han Jung-Min , Cheol Koo Hyun , Min Byoung-Chul , Kim Hyung-jun , Chang Joonyeon , Hee Han Suk , Ho Lim Sang
Published: February 2013

The transport of perpendicular spins in a GaAs channel is investigated via a fully electrical method. A Tb20Fe62Co18/Co40Fe40B20/MgO contact is used to inject perpendicular spin into the GaAs channel, where the Tb20Fe62Co18 layer produces perpendicular magnetization and the Co40Fe40B20 layer enhances the spin polarization of the injection current. By measuring the three-terminal Hanle effect with an in-plane field, we obtained a spin signal of 0.65 Ω (0.04 Ω) and a spin lifetime of 0.30 ns (0.17 ns) at 1.8 K (300 K). The observed spin signal with a MgO barrier is more than double of that without a MgO barrier.
High aspect ratio composite structures with 48.5% thermal neutron detection efficiency
Authors: Shao Q. , Voss L. F. , Conway A. M. , Nikolic R. J. , Dar M. A. , Cheung C. L.
Published: February 2013

The pillar structured thermal neutron detector is based on the combination of high aspect ratio silicon p-i-n pillars surrounded by the neutron converter material 10B. By etching high aspect ratio pillar structures into silicon, the result is a device that efficiently absorbs the thermal neutron flux by accommodating a large volume fraction of 10B within the silicon pillar array. Here, we report a thermal neutron detection efficiency of 48.5% using a 50 μm pillar array with an aspect ratio of 25:1.
Host–rabies virus protein–protein interactions as druggable antiviral targets
Authors: Lingappa Usha F. , Wu Xianfu , Macieik Amanda , Yu Shao Feng , Atuegbu Andy , Corpuz Michael , Francis Jean , Nichols Christine , Calayag Alfredo , Shi Hong , Ellison James A. , Harrell Emma K. T. , Asundi Vinod , Lingappa Jaisri R. , Prasad M. Dharma , Lipkin W. Ian , Dey Debendranath , Hurt Clarence R. , Lingappa Vishwanath R. , Hansen William J. , Rupprecht Charles E.
Published: February 2013

We present an unconventional approach to antiviral drug discovery, which is used to identify potent small molecules against rabies virus. First, we conceptualized viral capsid assembly as occurring via a host-catalyzed biochemical pathway, in contrast to the classical view of capsid formation by self-assembly. This suggested opportunities for antiviral intervention by targeting previously unappreciated catalytic host proteins, which were pursued. Second, we hypothesized these host proteins to be components of heterogeneous, labile, and dynamic multi-subunit assembly machines, not easily isolated by specific target protein-focused methods. This suggested the need to identify active compounds before knowing the precise protein target. A cell-free translation-based small molecule screen was established to recreate the hypothesized interactions involving newly synthesized capsid proteins as host assembly machine substrates. Hits from the screen were validated by efficacy against infectious rabies virus in mammalian cell culture. Used as affinity ligands, advanced analogs were shown to bind a set of proteins that effectively reconstituted drug sensitivity in the cell-free screen and included a small but discrete subfraction of cellular ATP-binding cassette family E1 (ABCE1), a host protein previously found essential for HIV capsid formation. Taken together, these studies advance an alternate view of capsid formation (as a host-catalyzed biochemical pathway), a different paradigm for drug discovery (whole pathway screening without knowledge of the target), and suggest the existence of labile assembly machines that can be rendered accessible as next-generation drug targets by the means described.
Anomalous superfluid density in quantum critical superconductors
Authors: Hashimoto Kenichiro , Mizukami Yuta , Katsumata Ryo , Shishido Hiroaki , Yamashita Minoru , Ikeda Hiroaki , Matsuda Yuji , Schlueter John A. , Fletcher Jonathan D. , Carrington Antony , Gnida Daniel , Kaczorowski Dariusz , Shibauchi Takasada
Published: February 2013

When a second-order magnetic phase transition is tuned to zero temperature by a nonthermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these “quantum critical” superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature
T

c

often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong critical fluctuations on the superconducting condensate below
T

c

is less well established. Here we report measurements of the magnetic penetration depth in heavy-fermion, iron-pnictide, and organic superconductors located close to antiferromagnetic quantum critical points, showing that the superfluid density in these nodal superconductors universally exhibits, unlike the expected
T
-linear dependence, an anomalous 3/2 power-law temperature dependence over a wide temperature range. We propose that this noninteger power law can be explained if a strong renormalization of effective Fermi velocity due to quantum fluctuations occurs only for momenta
k
close to the nodes in the superconducting energy gap Δ(
k
). We suggest that such “nodal criticality” may have an impact on low-energy properties of quantum critical superconductors.
The Foregrounding of Homelessness in Iran by a Progressive Media
Authors: Fateh Abolfazl
Published: February 2013

The case of “homelessness in Iran” presents empirical evidence to demonstrate “how a small media organization affects and changes social discourse.” The study investigates how the Iranian Students News Agency (ISNA) embodied the view of a news agency as having a role not only in the coverage of events, but also as an active agent of social change through discursive interventions. The process by which ISNA reconstructed homelessness and its empirical consequences is compatible with the five accepted stages labeled by Blumer. Homelessness represents the different ways in which ISNA has intervened in the social discourse in Iran: foregrounding a social issue, thematizing a discourse and problematizing social issues in order to open up a new kind of discourse.
Russo-Iranian Political Relations in the First Decade of the Twenty-First Century
Authors: Dunaeva Elena
Published: February 2013

In the 1990s, Russia and Iran successfully laid the foundations for interaction and expanded their spheres of cooperation. At the beginning of the twenty-first century, their relations developed unevenly. These fluctuations depended on the combination of global and regional factors, as well as on the internal circumstances in each country. Russia's participation in international sanctions has aroused discontent in Iran. Despite this, the political establishments of both countries continue to demonstrate an interest in developing bilateral relations and to reaffirm their shared geopolitical interests. This paper analyzes foreign policy documents and the latest research by Russian and Iranian scholars. It strives to shed light on the question: “To what extent and in what areas do the interests of Russia and Iran coincide, and what is the foundation for their potential future development?”
National, supranational, international: New Belgrade and the symbolic construction of a socialist capital
Authors: Kulić Vladimir
Published: February 2013

The construction of New Belgrade as the new capital of socialist Yugoslavia was the most symbolic modernizing act initiated by the country's communist government. Yet, its precise meanings were suspended between the complicated and permanently transitory concepts of socialist Yugoslavia's federalism and its international aspirations. Focusing on three characteristic “snapshots” of the city's physical development, this paper analyzes how New Belgrade and its most important buildings represented the shifting concepts of socialist Yugoslavia as a multiethnic community and its even more changeable place in the world. The first snapshot deals with the years immediately following World War II, during which New Belgrade was conceived as the seat of a centralized Stalinist state in close alliance with the USSR. The second deals with the effects of Yugoslavia's break from the Soviet bloc in 1948, especially its rapprochement with the West and the start of the decentralization of the federal state. Finally, the third explores the late socialist period: the dwindling of New Belgrade's role as the political heart of the federation, and at the same time its emergence as a locus of Yugoslavia's ambition to play a leading role in international relations, especially through its activity in the Non-Aligned Movement.
The cerebellum in Parkinson’s disease
Authors: Wu Tao , Hallett Mark
Published: February 2013

Parkinson’s disease is a chronic progressive neurodegenerative disorder characterized by resting tremor, slowness of movements, rigidity, gait disturbance and postural instability. Most investigations on Parkinson’s disease focused on the basal ganglia, whereas the cerebellum has often been overlooked. However, increasing evidence suggests that the cerebellum may have certain roles in the pathophysiology of Parkinson’s disease. Anatomical studies identified reciprocal connections between the basal ganglia and cerebellum. There are Parkinson’s disease–related pathological changes in the cerebellum. Functional or morphological modulations in the cerebellum were detected related to akinesia/rigidity, tremor, gait disturbance, dyskinesia and some non-motor symptoms. It is likely that the major roles of the cerebellum in Parkinson’s disease include pathological and compensatory effects. Pathological changes in the cerebellum might be induced by dopaminergic degeneration, abnormal drives from the basal ganglia and dopaminergic treatment, and may account for some clinical symptoms in Parkinson’s disease. The compensatory effect may help maintain better motor and non-motor functions. The cerebellum is also a potential target for some parkinsonian symptoms. Our knowledge about the roles of the cerebellum in Parkinson’s disease remains limited, and further attention to the cerebellum is warranted.
Probing the nature of compact ultrasteep spectrum radio sources with the e-EVN and e-MERLIN
Authors: Argo M. K. , Paragi Z. , Röttgering H. , Klöckner H.-R. , Miley G. , Mahmud M.
Published: February 2013

We present first results from electronic Multi-Element Remotely Linked Interferometer Network and electronic European VLBI Network observations of a small sample of ultrasteep spectrum radio sources, defined as those sources with a spectral index α < −1.4 between 74 and 325 MHz, which are unresolved on arcsecond scales. Such sources are currently poorly understood and a number of theories as to their origin have been proposed in the literature. The new observations described here have resulted in the first detection of two of these sources at milliarcsecond scales and show that a significant fraction of ultrasteep spectrum sources may have compact structures which can only be studied at the high resolution available with very long baseline interferometry (VLBI).
Procedural And Substantive Practical Rationality
Authors: Hooker Brad , Streumer Bart
Published: February 2013

This article explains the distinction between procedural and substantive practical rationality. According to proceduralism, an agent is open to rational criticism for lacking a desire only if she fails to have a desire that she can rationally reach from her beliefs and other desires, whereas according to substantivism, an agent is open to such criticism not only if her desires fail procedurally, but also if they fail substantively—where, for example, an agent who lacks the desire to take curative medicine might be substantively irrational in virtue of this lack, and yet be procedurally rational because she cannot rationally reach this desire from her beliefs and other desires. This article discusses the proceduralist views of Hume, Brandt, and Williams, before turning to substantivist arguments. It concludes by noting the advantages of following Scanlon in being a proceduralist about practical rationality but a substantivist about practical reasons.
Introduction: Latin America—The Limitations and Meaning of A Historical Category
Authors: Moya Jose C.
Published: February 2013

The introductory article addresses the following issue: the limitations and meaning of Latin America as a historical category. It does so in consecutive sections that explore other categories that could be more meaningful than the categories of Latin and North in the conceptual organization of space within the Americas; the commonalities that distinguish the Americas from the rest of the world; the commonalities that distinguish Latin America from both the rest of the Americas and the rest of the colonized world; and the reasons why a region that is in the Western Hemisphere in many more ways than geographically became excluded from “the West”.
A Case for Positive Psychology
Authors: Lopez Shane J. , Gallagher Matthew W.
Published: February 2013

Pickup a magazine or a scholarly psychology journal and, chances are, you will read about the good work of a positive psychologist. Through the use of sound methods, positive psychologists answer hard questions about the best in people. This book serves as repository of answers to those tough questions. In this chapter, we argue that the work of positive psychology scholars is good for psychology, as a discipline, and for society. We also discuss what needs to be done to shore up the science and practice of positive psychology.
Stopping the “Madness”: Positive Psychology and Deconstructing the Illness Ideology and the DSM
Authors: Maddux James E.
Published: February 2013

This chapter describes the traditional view of clinical psychology as a discipline and profession that is steeped in an “illness ideology.” This illness ideology has roots in clinical psychology's early connections with psychiatry and medicine and limits clinical psychology to the study of what is worst and weakest about people rather than what is best and bravest about people. The historical, cultural, and professional causes of this ideology are discussed, with an emphasis on the social construction and deconstruction of the Diagnostic and Statistical Manual of Mental Disorders as the manifestation of the illness ideology that has the greatest detrimental influence on clinical psychology. The chapter also proposes that the illness ideology be replaced with a positive psychology ideology that emphasizes well-being, satisfaction, happiness, interpersonal skills, perseverance, talent, wisdom, personal responsibility, and what makes life worth living.
Toward a Science of Mental Health
Authors: Keyes Corey L. M.
Published: February 2013

This chapter summarizes the research on the dual-continua model of mental health and mental illness. Studies supported this model and therefore the view that the presence of mental health is more than the absence of mental illness. Mental health is conceived of as a constellation of dimensions of subjective well-being, specifically hedonic and eudaemonic measures of subjective well-being. Specifically, the mental health continuum ranges from languishing, moderate, to flourishing mental health. These classifications are important for distinguishing and predicting level of functioning for individuals with and without a current mental disorder. Among individuals free of a mental disorder, flourishing individuals report the fewest missed days of work, the fewest half-day or greater work cutbacks, the healthiest psychosocial functioning, high resilience, and high intimacy), the lowest risk of cardiovascular disease, the lowest number of chronic physical diseases at all ages, the fewest health limitations of activities of daily living, and lower health-care utilization. Even among adults with a mental disorder during the past 12 months, those who are flourishing functioned better than those with moderate mental health, who in turn functioned better than those who were languishing. The findings strongly support the adoption of a more positive paradigm to treatment, prevention, and promotion of population mental health.
Positive Affectivity: The Disposition to Experience Positive Emotional States
Authors: Watson David , Naragon Kristin
Published: February 2013

Positive affectivity is a trait that reflects stable individual differences in positive emotional experience; high levels of the trait are marked by frequent feelings of cheerfulness, enthusiasm, and energy. Positive affectivity is relatively independent from negative affectivity, as these traits developed in response to different evolutionary pressures. Similar to personality traits, trait affect is structured hierarchically. Although there is not a clear consensus regarding the lower-order components of positive affectivity, we emphasize a model that includes components of Joviality, Self-Assurance, and Attentiveness. Different measures of positive affectivity are reviewed, as well as relations to overlapping constructs such as extraversion, happiness, and subjective well-being.

In terms of its biological bases, positive affectivity is moderately heritable and is linked to left prefrontal brain activation, likely mediated by the dopaminergic system. There are few demographic or environmental factors that are systematically related to levels of positive affectivity; for instance, the trait does not differ according to age or gender. However, frequency of social activity and identification as religious/spiritual are both positively correlated with positive affectivity.

Positive affect is relevant to a number of important domains. For example, low levels of positive affectivity are characteristic of numerous psychological disorders (particularly depression). Current marital and job satisfaction can be predicted based on previous measurement of positive affectivity. Positive affectivity is also related to better physical health, such as increased resistance to infectious illnesses. Finally, although mean levels of positive affectivity do not appear to differ greatly across cultures, there is evidence that culture may influence cross-situational stability and perceptions of trait affect. We conclude by showing that although temperament is an important factor in determining levels of positive affectivity, individuals are still free to take action to increase their happiness in lasting ways.
Problem-Solving Appraisal and Psychological Adjustment
Authors: Heppner P. Paul , Lee Dong-Gwi , Tian Lu
Published: February 2013

How people typically respond to life's problems is of critical importance, particularly how they appraise their problem-solving skills and whether they generally approach or avoid the many problems of life. A critical strength or resource for coping with life's demands is a person's appraisal of his or her problem-solving skills and style. This chapter focuses on how problem-solving appraisal has been empirically demonstrated to be an important asset in living and an important component of positive psychology. Specifically, it begins with a brief history of applied problem-solving appraisal, followed by how it is measured. The Problem Solving Inventory (PSI) has been one of the most widely used self-report inventories in applied problem solving; the PSI has a strong empirical base, and it is strongly linked to a wide range of indices of psychological adjustment, physical health, a wide array of coping activities, and vocational adjustment. The chapter also provides a brief overview of problem-solving training interventions, and finally future research directions and conclusions. Because problem-solving appraisal is learned, this implies that it is amenable to change; this provides hope for millions of people to bring positive change to their lives through the integration of problem solving and positive psychology.
Empathy and Altruism
Authors: Batson C. Daniel , Ahmad Nadia , Lishner David A.
Published: February 2013

Do we humans ever, in any degree, care about others for their sakes and not simply for our own? Psychology has long assumed that everything humans do, no matter how nice and noble, is motivated by self-interest. However, research over the past three decades suggests that this assumption is wrong. This research has focused on the empathy—altruism hypothesis, which claims that empathic concern—an other-oriented emotional response elicited by and congruent with the perceived welfare of a person in need—produces altruistic motivation—motivation with the ultimate goal of increasing another's welfare. Results of the over 30 experiments designed to test this hypothesis against various egoistic alternatives have proved remarkably supportive, leading to the tentative conclusion that feeling empathic concern for a person in need does indeed evoke altruistic motivation to see that need relieved. Sources of altruistic motivation other than empathy also have been proposed, but as yet, there is not compelling research evidence to support these proposals. Two additional forms of prosocial motivation have also been proposed: collectivism and principlism. Collectivism—motivation with the ultimate goal of benefiting some group or collective as a whole—has been claimed to result from group identity. Principlism—motivation with the ultimate goal of upholding some moral principle—has long been advocated by religious teachers and moral philosophers. Whether either is a separate form of motivation, independent of and irreducible to egoism, is not yet clear. Research done to test for the existence of empathy-induced altruism may serve as a useful model for future research testing for the existence of collectivism and principlism. Theoretical and practical implications of the empathy-altruism hypothesis are briefly considered.
The Motive for Distinctiveness: A Universal, but Flexible Human Need
Authors: Vignoles Vivian L.
Published: February 2013

Existential and evolutionary reasoning converge to suggest that humans in all historical and cultural settings will have an enduring and universal need to distinguish themselves from others and their ingroups from outgroups. European and North American studies suggest that people use a variety of positive and negative strategies to maintain their distinctiveness and that these strategies tend to be intensified when distinctiveness is threatened or undermined. Yet, there also appear to be significant individual and cultural differences in distinctiveness seeking, as evidenced by “need for uniqueness” measures; an important question is to what extent these measures capture true variation in the strength of the underlying need for distinctiveness, as opposed to variation in the perceived value of particular forms of distinctiveness or in the particular ways in which feelings of distinctiveness can be achieved. Research suggests that distinctiveness seeking is not reducible to the effects of other identity motives, such as self-esteem concerns; however, the relationship between motives for distinctiveness and belonging is an important avenue for further research. Given that distinctiveness seeking appears to be a fundamental human need, positive psychologists should focus on trying to channel the effects of this motive into more productive routes (e.g., creativity) rather than harmful ones (e.g., discrimination against outgroups). To the extent that benign and beneficial forms of distinctiveness seeking are available, valued, and encouraged in society, more harmful responses potentially may be reduced.
A Role for Neuropsychology in Understanding the Facilitating Influence of Positive Affect on Social Behavior and Cognitive Processes
Authors: Isen Alice M.
Published: February 2013

This chapter summarizes findings showing that mild positive affect facilitates thinking, problem solving, and social interaction through increased cognitive flexibility and explores a possible role for neuropsychology in understanding these effects. Several lines of research show that mild happy feelings, induced in everyday ways that people often encounter in the course of their daily lives, promote effective thinking and problem solving by enabling flexible thinking that allows the person to respond to the situation in its complex context. Studies have demonstrated that positive affect engenders motives such as kindness, helpfulness, and generosity, but also positive-affect maintenance and fairness to oneself as well as to others. Recent work is showing that one reason this occurs is because positive affect facilitates cognitive flexibility characterized by openness to useful information (even if it is negative in tone), reduced “defensiveness,” and the ability to see multiple sides of the situation and switch attention among them. This ability to hold multiple ideas or facets of a situation in mind, in turn, fosters a better ability to solve complex problems, both interpersonal and nonsocial. Another result of this kind of openness to information and cognitive flexibility that is fostered by positive affect is increased enjoyment of variety in safe situations and improved ability to deal with a large, complex decision task or set of material or options. Another, however, is reduced risk taking in dangerous situations, as people—although more optimistic about winning—are also more aware of the negative utility or consequences of a loss. Most recently, research is focusing on positive affect's beneficial effect on self-control of several types, including its facilitation of flexible attention deployment that enables both broadened attention and focus on a target task. This ability is reflected in superior incidental learning and divided attention, without impaired performance on the target task. This chapter summarizes some of these findings and explores a possible role for neuropsychology in understanding these effects, arguing not for the superiority of one level of analysis (behavioral, cognitive, neuropsychological) over others, but for their integration and a search for the ways in which each can contribute to the others.
Positive Workplaces
Authors: Luthans Fred , Youssef Carolyn M.
Published: February 2013

Over the years, both management practitioners and academics have generally assumed that positive workplaces lead to desired outcomes. Unlike psychology, considerable attention has also been devoted to the study of positive topics such as job satisfaction and organizational commitment. However, to place a scientifically based focus on the role that positivity may play in the development and performance of human resources, and largely stimulated by the positive psychology initiative, positive organizational behavior (POB) and psychological capital (PsyCap) have recently been introduced into the management literature. This chapter first provides an overview of both the historical and contemporary positive approaches to the workplace. Then, more specific attention is given to the meaning and domain of POB and PsyCap. Our definition of POB includes positive psychological capacities or resources that can be validly measured, developed, and have performance impact. The constructs that have been determined so far to best meet these criteria are efficacy, hope, optimism, and resiliency. When combined, they have been demonstrated to form the core construct of what we term psychological capital (PsyCap). A measure of PsyCap is being validated and this chapter references the increasing number of studies indicating that PsyCap can be developed and have performance impact. The chapter concludes with important future research directions that can help better understand and build positive workplaces to meet current and looming challenges.
Meditation and Positive Psychology
Authors: Shapiro Shauna L.
Published: February 2013

Mental health, once defined in terms of absence of illness, has gradually become understood in a more holistic way, which also includes the positive qualities that help people flourish. This evolving definition of mental health has led to an exploration of other traditions and practices, including meditation, which for thousands of years have been devoted to developing an expanded vision of human potential. One result was the introduction of the practice of meditation into Western scientific study. However, the principal original intentions of meditation, to uncover the positive and to catalyze our internal potential for healing and development, have been largely ignored by the scientific community. Yet, a small number of researchers and theorists have explored and continue to explore the positive effects of meditation. The chapter focuses on this pioneering work.
Benefit-Finding and Growth
Authors: Lechner Suzanne C. , Tennen Howard , Affleck Glenn
Published: February 2013

Following adverse life events, many people report positive outcomes, sometimes referred to as benefit finding and growth (or BFG). Some people experience a new appreciation of their own strength and resilience or an increased self-reliance. Others describe strengthened relationships and increased closeness with others, greater compassion or altruism, a heightened sense of the fragility of life, or changes in life philosophies and spirituality. This chapter addresses several unresolved issues in the study of BFG, including whether an individual's ability to find benefits in a stressful or traumatic life event is an important contributor to subsequent quality of life and adjustment; how BFG perceptions develop and are maintained over time; shortcomings of current indicators purporting to measure benefits in the context of adversity; future directions for research in this area; and clinical applications of research in BFG. In this chapter, we take a new look at the BFG literature, revisit concerns identified in the first edition of this Handbook, and raise new concerns regarding how BFG is currently assessed and translated into new treatments. We caution against the rush to create interventions to enhance BFG in light of the potential detrimental effects on victimized individuals created by our societal emphasis on the power of positive thinking.
The Future of Positive Psychology: Pursuing Three Big Goals
Authors: Lopez Shane J.
Published: February 2013

Good positive psychological science is being disseminated to the general public. In turn, consumers are asking for solid, real-world applications of the science to make daily life better for individuals, families, and communities at large. Now, scientists, practitioners, and the consumers of our scholarly products potentially can collaborate to drive systemic changes in schools, families, and workplaces. In this chapter, I set three aspirational goals for positive psychology applications that could marshal the talent and resources of change agents throughout society.
Memory and Learning in Intellectual Disabilities
Authors: Vicari Stefano
Published: February 2013

This chapter reviews the neuropsychological literature and recent experimental studies on long-term memory and learning development in intellectual disabilities (ID), particularly in genetic syndromes. The main goal is to report specific profiles of memory capacities (with some components more preserved and others more impaired) in people with ID of different etiologies but similar severity. Consistently with a neuropsychological approach, distinct memory profiles in ID and, more specifically, in genetic syndromes can be traced to the characteristics of their brain development and architecture. Therefore, the possible correlation between memory profiles and brain development will also be presented and discussed.
Massive Modularity
Authors: Samuels Richard
Published: February 2013

The objective of the article is to discuss the evolution, hypothesis, and some the more prominent arguments for massive modularity (MM). MM is the hypothesis that the human mind is largely or entirely composed from a great many modules. Modules are functionally characterizable cognitive mechanisms that tend to possess several features, which include domain-specificity, informationally encapsulation, innateness, inaccessibility, shallow outputs, and mandatory operation. The final thesis that comprises MM mentions that modules are found not merely at the periphery of the mind but also in the central regions responsible for such higher cognitive capacities as reasoning and decision-making. The central cognition depends on a great many functional modules that are not themselves composable into larger more inclusive systems. One of the families of arguments for MM focuses on a range of problems that are familiar from the history of cognitive science such as problems that concern the computational tractability of cognitive processes. The arguments may vary considerably in detail but they share a common format. First, they proceed from the assumption that cognitive processes are classical computational ones. Second, given the assumption that cognitive processes are computational ones, intractability arguments seek to undermine non-modular accounts of cognition by establishing the intractability thesis.
Computationalism
Authors: Piccinini Gualtiero
Published: February 2013

The introduction of the concept of computation in cognitive science is discussed in this article. Computationalism is usually introduced as an empirical hypothesis that can be disconfirmed. Processing information is surely an important aspect of cognition so if computation is information processing, then cognition involves computation. Computationalism becomes more significant when it has explanatory power. The most relevant and explanatory notion of computation is that associated with digital computers. Turing analyzed computation in terms of what are now called Turing machines that are the kind of simple processor operating on an unbounded tape. Turing stated that any function that can be computed by an algorithm could be computed by a Turing machine. McCulloch and Pitts's account of cognition contains three important aspects that include an analogy between neural processes and digital computations, the use of mathematically defined neural networks as models, and an appeal to neurophysiological evidence to support their neural network models. Computationalism involves three accounts of computation such as causal, semantic, and mechanistic. There are mappings between any physical system and at least some computational descriptions under the causal account. The semantic account may be formulated as a restricted causal account.