Energy and momentum relaxation dynamics of hot holes in modulation doped GaInNAs/GaAs quantum wells

We present the studies of energy and momentum relaxation dynamics of nonequilibrium holes in GaxIn1−xNyAs1−y/GaAs quantum well modulation doped with Be. Experimental results show that the real-space transfer (RST) of hot holes occurs via thermionic emission from the high-mobility GaInNAs quantum wells into the low-mobility GaAs barriers at a threshold electric field of F ∼ 6 kV/cm at T = 13 K. At this field the hole drift velocity saturates at vd ∼ 1×107 cm/s. A slight increase in the field above the threshold leads to the impact ionization of acceptors in the barriers by the nonequilibrium holes. We observe and model theoretically a negative differential mobility effect induced by RST that occurs at an electric field of F ∼ 7 kV/cm. The observed current surge at electric fields above 7 kV/cm is attributed to the hole multiplication induced by shallow impurity breakdown in the GaAs barrier and impact ionization in the high-field domain regime associated with the packet of RST of holes in the well

Superconductivity in heavily compensated Mg-doped InN

We report superconductivity in Mg-doped InN grown by molecular beam epitaxy. Superconductivity phase transition temperature occurs Tc = 3.97 K as determined by magnetoresistance and Hall resistance measurements. The two-dimensional (2D) carrier density of the measured sample is n2D = 9×1014 cm−2 corresponding to a three-dimensional (3D) electron density of n3D = 1.8×1019 cm−3 which is within the range of values between Mott transition and the superconductivity to metal transition. We propose a plausible mechanism to explain the existence of the superconductivity in terms of a uniform distribution of superconducting InN nanoparticles or nanosized indium dots forming microscopic Josephson junctions in the heavily compensated insulating bulk InN matrix

How financial markets process money information: A re-examination of evidence using band spectrum regression

Cataloged from PDF version of article.This article re-examines the response of financial markets to money supply announcements. It is argued that the previous research in the area may be suffering from an estimation bias. The potential for estimation bias stems from the questionable practice of assuming the same regression model for all frequency bands. A decomposition of the data into low-frequency and high-frequency components raises the possibility that both expected liquidity and expected inflation effects are in operation simultaneously though they affect different expectation horizons. The results also show that the distinct weight of these separate effects depends essentially on the credibility of the Fed in adhering to announced monetary targets and the state of inflationary fears

Carrier trapping and escape times in p-i-n GaInNAs MQW structures

We used a semi-classical model to describe carrier capture into and thermionic escape from GaInNAs/GaAs multiple quantum wells (MQWs) situated within the intrinsic region of a GaAs p-i-n junction. The results are used to explain photocurrent oscillations with applied bias observed in these structures, in terms of charge accumulation and resonance tunnelling

GaInNAs-based Hellish-vertical cavity semiconductor optical amplifier for 1.3 μm operation

Hot electron light emission and lasing in semiconductor heterostructure (Hellish) devices are surface emitters the operation of which is based on the longitudinal injection of electrons and holes in the active region. These devices can be designed to be used as vertical cavity surface emitting laser or, as in this study, as a vertical cavity semiconductor optical amplifier (VCSOA). This study investigates the prospects for a Hellish VCSOA based on GaInNAs/GaAs material for operation in the 1.3-μm wavelength range. Hellish VCSOAs have increased functionality, and use undoped distributed Bragg reflectors; and this coupled with direct injection into the active region is expected to yield improvements in the gain and bandwidth. The design of the Hellish VCSOA is based on the transfer matrix method and the optical field distribution within the structure, where the determination of the position of quantum wells is crucial. A full assessment of Hellish VCSOAs has been performed in a device with eleven layers of Ga0.35In0.65N0.02As0.08/GaAs quantum wells (QWs) in the active region. It was characterised through I-V, L-V and by spectral photoluminescence, electroluminescence and electro-photoluminescence as a function of temperature and applied bias. Cavity resonance and gain peak curves have been calculated at different temperatures. Good agreement between experimental and theoretical results has been obtained

Abspaltung ortho-ständiger Substituenten aus ionisierten Phenyl-2-propanonen nach Elektronenstoßaktivierung

Die Molekülionen der Phenyl-2-propanone 2a-4a verlieren positionsspezifisch o-ständige Cl -, Br - bzw. I -Atome unter Bildung von (M-Hal')+- Ionen (m/z 133) hoher Intensität (70/12 eV; 1. und 2. FFR) und identischer Struktur (MIKE-CAD-Spektren). Die Fragmentionen bei m/z 133 aus o- Chlorphenyl-2-propanon (2a) und 2,2-Dimethyl-2,3-dihydro[fc]furan (11) sind von ähnlicher, aber nicht identischer Struktur. Die stoßaktivierten (2. FFR) (M-Br*)+-Ionen aus o-Bromphenyl-2-propanon (3a) und 1-Brom-lphenyl- 2-propanon (12) liefern praktisch deckungsgleiche Spektren. Die Hauptreaktion der (M-Hal')+-Ionen aus 2a-4a ist die Abspaltung von CO, das ausschließlich das C-Atom der Carbonylgruppe enthält (13C-Markierung). Der mechanistische Verlauf der Reaktionsfolge wird diskutiert (Abb. 5 und 8). In the gas phase, the phenyl-2-propanone molecules 2a-4a lose upon electron impact chloro-, bromo-, and iodo-radicals specifically at the orthoposition of the phenyl group giving rise to strong (M-Hal')+-ions (70/12 eV; 1st and 2nd FFR) of identical structure as confirmed by their MIKECAD- spectra. The daughter ions at m/z 133 from o-chlorophenyl-2-propanone (2a) and 2,2-dimethyl-2,3-dihydro[b]furane (11) are structurally similar but not identical (similarity index 99.8). The collisionally activated (2nd FFR) (M-Br')+-ions from o-bromophenyl-2-propanone (3a) and 1- bromo-1-phenyl-2-propanone (12) produce virtually congruent spectra. The most important subsequent fragmentation of the (M-Hal')+-ions from 2a-4a is the loss of CO which incorporates the C-atom of the carbonyl group exclusively (13C labelling). Mechanistic aspects of the fragmentation sequences are discussed (Figs. 5 and 8)

Death rates from malaria epidemics, Burundi and Ethiopia.

Death rates exceeded emergency thresholds at 4 sites during epidemics of Plasmodium falciparum malaria in Burundi (2000-2001) and in Ethiopia (2003-2004). Deaths likely from malaria ranged from 1,000 to 8,900, depending on site, and accounted for 52% to 78% of total deaths. Earlier detection of malaria and better case management are needed

THE RELATIONSHIP BETWEEN TRUST, TURNOVER INTENTIONS AND EMOTIONS: AN APPLICATION

Managerial leaders and directors are required to succeed the method of “sense” and “emotion” very well, to achieve organizational aims (Lee, 2002). Organizations need to manage all the emotions and feelings and concepts that affect persons health and performance (Gross, 1999). Business life dealing with this issue has increased in seriousness because, the effect of emotions in decision making cleared with academic studies. There is a need to find the path to the correct leadership of emotions. Emotions in the organization help to identify thoughts about the presence and desire to work (Jackson, 2006). The main purpose of this study, which should be considered a descriptive survey in the general sense, is to investigate the relationship between emotional expressions, trust and turnover intentions. Two different surveys were used in order to measure and assess the emotions expressions, trust and turnover intentions. The survey conducted on 200 employees of the public sector institution. Data, obtained from questionnaires analyzed through the SPSS statistical packaged software. We found that especially trust factors (Trust in management, co-worker trust and trust to manager) had a significant effect on “satisfaction” factor of turnover intentions. In addition, we found that “Co-worker trust” had a negative and significant effect on “Seek for job” factor of turnover intentions

High Efficacy of Two Artemisinin-Based Combinations (Artesunate + Amodiaquine and Artemether + Lumefantrine) in Caala, Central Angola.

In April 2004, 137 children 6-59 months of age with uncomplicated Plasmodium falciparum (Pf) malaria (Caala, Central Angola) were randomized to receive either artemether-lumefantrine (Coartem) or artesunate + amodiaquine (ASAQ). After 28 days of follow-up, there were 2/61 (3.2%) recurrent parasitemias in the Coartem group and 4/64 (6.2%) in the ASAQ group (P = 0.72), all classified as re-infections after PCR genotyping (cure rate = 100% [95%CI: 94-100] in both groups). Only one patient (ASAQ group) had gametocytes on day 28 versus five (Coartem) and three (ASAQ) at baseline. Compared with baseline, anemia was significantly improved after 28 days of follow-up in both groups (Coartem: from 54.1% to 13.4%; ASAQ: from 53.1% to 15.9%). Our findings are in favor of a high efficacy of both combinations in Caala. Now that Coartem has been chosen as the new first-line anti-malarial, the challenge is to insure that this drug is available and adequately used