Progress Monitoring Using Direct Behavior Rating Single Item Scales in a Multiple-Baseline Design Study of the Daily Report Card Intervention

ERIC Educational Resources Information Center

Fabiano, Gregory A.; Pyle, Kellina; Kelty, Mary Bridget; Parham, Brittany R.

2017-01-01

Direct behavior rating (DBR) may be a viable assessment for documenting current areas of impaired functioning and progress monitoring students' response to a behavioral intervention. Challenging behaviors are often addressed in general education settings using interventions such as the daily report card (DRC). To best implement and monitor such…

Human DBR1 modulates the recycling of snRNPs to affect alternative RNA splicing and contributes to the suppression of cancer development.

PubMed

Han, B; Park, H K; Ching, T; Panneerselvam, J; Wang, H; Shen, Y; Zhang, J; Li, L; Che, R; Garmire, L; Fei, P

2017-09-21

The contribution of RNA processing to tumorigenesis is understudied. Here, we report that the human RNA debranching enzyme (hDBR1), when inappropriately regulated, induces oncogenesis by causing RNA processing defects, for example, splicing defects. We found that wild-type p53 and hypoxia-inducible factor 1 co-regulate hDBR1 expression, and insufficient hDBR1 leads to a higher rate of exon skipping. Transcriptomic sequencing confirmed the effect of hDBR1 on RNA splicing, and metabolite profiling supported the observation that neoplasm is triggered by a decrease in hDBR1 expression both in vitro and in vivo. Most importantly, when modulating the expression of hDBR1, which was found to be generally low in malignant human tissues, higher expression of hDBR1 only affected exon-skipping activity in malignant cells. Together, our findings demonstrate previously unrecognized regulation and functions of hDBR1, with immediate clinical implications regarding the regulation of hDBR1 as an effective strategy for combating human cancer.

Rate of duodenal-biliary reflux increases in patients with recurrent common bile duct stones: evidence from barium meal examination.

PubMed

Zhang, Rongchun; Luo, Hui; Pan, Yanglin; Zhao, Lina; Dong, Junqiang; Liu, Zhiguo; Wang, Xiangping; Tao, Qin; Lu, Guohua; Guo, Xuegang

2015-10-01

Stone recurrence is a common late adverse event after ERCP in patients with common bile duct stones (CBDS). Duodenal-biliary reflux (DBR) is considered a major cause of CBDS recurrence. However, specific evidence is still lacking. To investigate the DBR rate in patients with recurrent CBDS after ERCP. A prospective case-control study. A tertiary center. During follow-up, patients with a history of either recurrent CBDS (recurrence group) or nonrecurrent CBDS (control group) were invited to participate in the study. All patients had previously undergone successful CBDS removal by ERCP. Patients in the control group were matched with the recurrence group by age and gender in a 1:1 ratio. Patients with gallbladder stones, hepatolithiasis, remnant CBDS, CBD strictures, or stents were excluded. Standard barium meal examination, MRCP, and enhanced abdominal CT. DBR. Thirty-two patients with a history of recurrent CBDS and 32 matched control subjects were enrolled. Baseline characteristics and parameters regarding the first ERCP were comparable between the 2 groups. The DBR rate was significantly higher in the recurrent than in the control group (68.8% vs 15.6%, P < .001). Multivariate analysis indicated that DBR (OR, 9.59; 95% CI, 2.65-34.76) and acute distal CBD angulation (OR, 5.48; 95% CI, 1.52-19.78) were independent factors associated with CBDS recurrence. DBR rates in patients with no, single, or multiple recurrences were 15.6%, 60.9%, and 88.9%, respectively (P < .001). Intrahepatic bile duct reflux was more common in patients with multiple recurrences. Small sample size. DBR is correlated with CBDS recurrence in patients who had previously undergone ERCP. DBR and acute distal CBD angulation are 2 independent risk factors related to stone recurrence. ( NCT02329977.) Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Kinetics of the reactions of alkyl radicals with HBr and DBr

NASA Technical Reports Server (NTRS)

Nicovich, J. M.; Van Dijk, C. A.; Kreutter, K. D.; Wine, P. H.

1991-01-01

The kinetics of the reactions CH3 + HBr, CD3 + HBr, CH3 + DBr, C2H5 + HBr, C2H5 + DBr, t-C4H9 + HBr, and t-C4H9 + DBr is studied as a function of temperature (257-430 K) and pressure (10-300 Torr of N2). Time-resolved resonance fluorescence detection of Br atom appearance following laser flash photolysis of RI was used in the experiments. Results show that the rates of all reactions increased as the temperature decreased.

Metal dependence and branched RNA cocrystal structures of the RNA lariat debranching enzyme Dbr1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Nathaniel E.; Katolik, Adam; Roberts, Kenneth M.

Intron lariats are circular, branched RNAs (bRNAs) produced during pre-mRNA splicing. Their unusual chemical and topological properties arise from branch-point nucleotides harboring vicinal 2',5'- and 3',5'-phosphodiester linkages. The 2',5'-bonds must be hydrolyzed by the RNA debranching enzyme Dbr1 before spliced introns can be degraded or processed into small nucleolar RNA and microRNA derived from intronic RNA. Here, we measure the activity of Dbr1 from Entamoeba histolytica by using a synthetic, dark-quenched bRNA substrate that fluoresces upon hydrolysis. Purified enzyme contains nearly stoichiometric equivalents of Fe and Zn per polypeptide and demonstrates turnover rates of ~3 s -1. Similar rates aremore » observed when apo-Dbr1 is reconstituted with Fe(II)+Zn(II) under aerobic conditions. Under anaerobic conditions, a rate of ~4.0 s -1 is observed when apoenzyme is reconstituted with Fe(II). In contrast, apo-Dbr1 reconstituted with Mn(II) or Fe(II) under aerobic conditions is inactive. Diffraction data from crystals of purified enzyme using X-rays tuned to the Fe absorption edge show Fe partitions primarily to the β-pocket and Zn to the α-pocket. Structures of the catalytic mutant H91A in complex with 7-mer and 16-mer synthetic bRNAs reveal bona fide RNA branchpoints in the Dbr1 active site. A bridging hydroxide is in optimal position for nucleophilic attack of the scissile phosphate. The results clarify uncertainties regarding structure/function relationships in Dbr1 enzymes, and the fluorogenic probe permits high-throughput screening for inhibitors that may hold promise as treatments for retroviral infections and neurodegenerative disease.« less

Comparison of distributed Bragg reflector ridge waveguide diode lasers and monolithic master oscillator power amplifiers

NASA Astrophysics Data System (ADS)

Werner, Nils; Wegemund, Jan; Gerke, Sebastian; Feise, David; Bugge, Frank; Paschke, Katrin; Tränkle, Günther

2018-02-01

Diode lasers with ridge waveguide structures and wavelength stabilization by a distributed Bragg-reflector (DBR) are key components for many different applications. These lasers provide diffraction limited laser emission in a single spectral mode, while an arbitrary emission wavelength can be chosen as long as the semiconductor allows for amplification. Furthermore, the DBR grating can be fabricated during the lateral structuring of the device which makes them well suited for mass production. A variety of different concepts can be used for the actual realization of the laser. While standard DBR ridge waveguide lasers (DBR-RWL) with a DBR as reflection grating provide up to 1W optical output power, the DBR can be also used as transmission grating for improved efficiency. Furthermore, more complex structures like monolithic master oscillator power amplifiers (MOPA), which show less spectral mode hops than DBR-RWLs, have been fabricated. The wide range of possible applications have different requirements on the emission characteristic of the used lasers. While the lasers can fulfill the requirements on the emission spectrum and the optical output power, the effects due to optical feedback from optical elements of the setup may limit their practical use in the respective application. Thus, it is of high importance to analyze the emission behavior of the different laser designs at various operation conditions with and without optical feedback. Here, the detailed investigation of the emission characteristics of lasers at an exemplary emission wavelength of 1120 nm is be presented.

GaAs/GaAlAs distributed Bragg reflector laser with a focused ion beam, low dose dopant implanted grating

NASA Technical Reports Server (NTRS)

Wu, M. C.; Boenke, M. M.; Wang, S.; Clark, W. M., Jr.; Stevens, E. H.

1988-01-01

The performance of a GaAs/GaAlAs distributed Bragg reflector (DBR) laser using a focused ion beam implanted grating (FIB-DBR) is reported for the first time. Stripes of Si(2+) with a period of 2300 A and a dose about 10 to the 14th/sq cm are directly implanted into the passive large optical cavity layer to provide the distributed feedback. Surface-emitting light from the second-order grating is observed. Threshold current of 110 mA and single DBR mode operation from 20 to 40 C are obtained. The wavelength tuning rate with temperature is 0.8 A/C. The coupling coefficient is estimated to be 15/cm. The results show that FIB technology is practical for distributed feedback and DBR lasers and optoelectronic integrated circuits.

Efficacy of 3,5-dibromo-L-phenylalanine in rat models of stroke, seizures and sensorimotor gating deficit

PubMed Central

Cao, W; Shah, HP; Glushakov, AV; Mecca, AP; Shi, P; Sumners, C; Seubert, CN; Martynyuk, AE

2009-01-01

Background and purpose: Abnormal glutamatergic activity is implicated in neurologic and neuropsychiatric disorders. Selective glutamate receptor antagonists were highly effective in animal models of stroke and seizures but failed in further clinical development because of serious side effects, including an almost complete set of symptoms of schizophrenia. Therefore, the novel polyvalent glutamatergic agent 3,5-dibromo-L-phenylalanine (3,5-DBr-L-Phe) was studied in rat models of stroke, seizures and sensorimotor gating deficit. Experimental approach: 3,5-DBr-L-Phe was administered intraperitoneally as three boluses after intracerebral injection of endothelin-1 (ET-1) adjacent to the middle cerebral artery to cause brain injury (a model of stroke). 3,5-DBr-L-Phe was also given as a single bolus prior to pentylenetetrazole (PTZ) injection to induce seizures or prior to the administration of the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) to cause disruption of prepulse inhibition (PPI) of startle (sensorimotor gating deficit). Key results: Brain damage caused by ET-1 was reduced by 52%, which is comparable with the effects of MK-801 in this model as reported by others. 3,5-DBr-L-Phe significantly reduced seizures induced by PTZ without the significant effects on arterial blood pressure and heart rate normally caused by NMDA antagonists. 3,5-DBr-L-Phe prevented the disruption of PPI measured 3 days after the administration of ET-1. 3,5-DBr-L-Phe also eliminated sensorimotor gating deficit caused by MK-801. Conclusion and implications: The pharmacological profile of 3,5-DBr-L-Phe might be beneficial not only for developing a therapy for the neurological and cognitive symptoms of stroke and seizures but also for some neuropsychiatric disorders. PMID:20050189

Efficacy of 3,5-dibromo-L-phenylalanine in rat models of stroke, seizures and sensorimotor gating deficit.

PubMed

Cao, W; Shah, H P; Glushakov, A V; Mecca, A P; Shi, P; Sumners, C; Seubert, C N; Martynyuk, A E

2009-12-01

Abnormal glutamatergic activity is implicated in neurologic and neuropsychiatric disorders. Selective glutamate receptor antagonists were highly effective in animal models of stroke and seizures but failed in further clinical development because of serious side effects, including an almost complete set of symptoms of schizophrenia. Therefore, the novel polyvalent glutamatergic agent 3,5-dibromo-L-phenylalanine (3,5-DBr-L-Phe) was studied in rat models of stroke, seizures and sensorimotor gating deficit. 3,5-DBr-L-Phe was administered intraperitoneally as three boluses after intracerebral injection of endothelin-1 (ET-1) adjacent to the middle cerebral artery to cause brain injury (a model of stroke). 3,5-DBr-L-Phe was also given as a single bolus prior to pentylenetetrazole (PTZ) injection to induce seizures or prior to the administration of the N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine (MK-801) to cause disruption of prepulse inhibition (PPI) of startle (sensorimotor gating deficit). Brain damage caused by ET-1 was reduced by 52%, which is comparable with the effects of MK-801 in this model as reported by others. 3,5-DBr-L-Phe significantly reduced seizures induced by PTZ without the significant effects on arterial blood pressure and heart rate normally caused by NMDA antagonists. 3,5-DBr-L-Phe prevented the disruption of PPI measured 3 days after the administration of ET-1. 3,5-DBr-L-Phe also eliminated sensorimotor gating deficit caused by MK-801. The pharmacological profile of 3,5-DBr-L-Phe might be beneficial not only for developing a therapy for the neurological and cognitive symptoms of stroke and seizures but also for some neuropsychiatric disorders.

Building bridges between theory and practice in medical education using a design-based research approach: AMEE Guide No. 60.

PubMed

Dolmans, Diana H J M; Tigelaar, D

2012-01-01

Medical education research has grown enormously over the past 20 years, but it does not sufficiently make use of theories, according to influential leaders and researchers in this field. In this AMEE Guide, it is argued that design-based research (DBR) studies should be conducted much more in medical education design research because these studies both advance the testing and refinement of theories and advance educational practice. In this Guide, the essential characteristics of DBR as well as how DBR differs from other approach such as formative evaluation are explained. It is also explained what the pitfalls and challenges of DBR are. The main challenges deal with how to insure that DBR studies reveal findings that are of a broader relevance than the local situation and how to insure that DBR contributes toward theory testing and refinement. An example of a series of DBR studies on the design of a teaching portfolio in higher education that is aimed at stimulating a teacher's professional development is described, to illustrate how DBR studies actually work in practice. Finally, it is argued that DBR-studies could play an important role in the advancement of theory and practice in the two broad domains of designing or redesigning work-based learning environments and assessment programs.

Efficiency enhancement and angle-dependent color change in see-through organic photovoltaics using distributed Bragg reflectors

NASA Astrophysics Data System (ADS)

Dong, Wan Jae; Lo, Nhat-Truong; Jung, Gwan Ho; Ham, Juyoung; Lee, Jong-Lam

2016-03-01

A distributed Bragg reflector (DBR) is conducted as a bottom reflector in see-through organic photovoltaics (OPVs) with an active layer of poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester (P3HT:PCBM). The DBR consists of alternative layers of the high- and low-refractive index materials of Ta2O5 (n = 2.16) and SiO2 (n = 1.46). The DBR selectively reflects the light within a specific wavelength region (490 nm-630 nm) where the absorbance of P3HT:PCBM is maximum. The see-through OPVs fabricated on DBR exhibit efficiency enhancement by 31% compared to the device without DBR. Additionally, the angle-dependent transmittance of DBR is analysed using optical simulation and verified by experimental results. As the incident angle of light increases, peak of reflectance shifts to shorter wavelength and the bandwidth gets narrower. This unique angle-dependent optical properties of DBR allows the facile color change of see-through OPVs.

Wireless Data Transmission at Terahertz Carrier Waves Generated from a Hybrid InP-Polymer Dual Tunable DBR Laser Photonic Integrated Circuit.

PubMed

Carpintero, Guillermo; Hisatake, Shintaro; de Felipe, David; Guzman, Robinson; Nagatsuma, Tadao; Keil, Norbert

2018-02-14

We report for the first time the successful wavelength stabilization of two hybrid integrated InP/Polymer DBR lasers through optical injection. The two InP/Polymer DBR lasers are integrated into a photonic integrated circuit, providing an ideal source for millimeter and Terahertz wave generation by optical heterodyne technique. These lasers offer the widest tuning range of the carrier wave demonstrated to date up into the Terahertz range, about 20 nm (2.5 THz) on a single photonic integrated circuit. We demonstrate the application of this source to generate a carrier wave at 330 GHz to establish a wireless data transmission link at a data rate up to 18 Gbit/s. Using a coherent detection scheme we increase the sensitivity by more than 10 dB over direct detection.

Experimental support for the effects of a probiotic/digestive enzyme supplement on serum cholesterol concentrations and the intestinal microbiome.

PubMed

Ichim, Thomas E; Patel, Amit N; Shafer, Kim A

2016-06-22

Elevated levels of blood cholesterol are associated with cardiovascular disease, a leading cause of morbidity and mortality worldwide. Current therapies for addressing elevated blood cholesterol can be inadequate, ineffective or associated with side effects; therefore, the search for additional therapies is ongoing. This study evaluated Daily Body Restore (DBR), a proprietary blend of 9 probiotic organisms of the genera Lactobacillus and Bifidobacterium, and 10 digestive enzymes, for its effects on cholesterol metabolism using an in vitro system and a mouse model. We used a murine model of hypercholesterolemia induced by a high fat diet to evaluate the effects of DBR on blood cholesterol concentrations. Hypercholesterolemic mice were supplemented with DBR in their drinking water for 8 weeks and compared to control mice given low fat diets or unsupplemented high fat diets. To evaluate the effects of DBR on the activity of gut microbiota in vitro, the Shime(®) system consisting of sequential colon reactors was supplemented with DBR for analysis of short chain fatty acid production. Analysis of hypercholesterolemic mice after 4 and 8 weeks of DBR supplementation revealed significant decreases in blood concentrations of low-density lipoprotein (LDL) and increases in high-density lipoprotein (HDL) while triglyceride concentrations were unaltered. Specifically, after 4 weeks of DBR supplementation, there was a 47 % decrease in LDL and a 32 % increase in HDL in peripheral blood compared to unsupplemented, high fat diet-fed mice. After 8 weeks of DBR treatment, LDL concentrations were dramatically reduced by 78 % and HDL was increased by 52 % relative to control mice. Addition of DBR to the Shime(®) system led to significantly increased production of propionate in colon reactors, indicative of microbial production of short chain fatty acids known to inhibit cholesterol synthesis. DBR, a probiotic and digestive enzyme supplement, lowered harmful LDL and increased HDL levels in a mouse model and also exerted in vitro effects consistent with cholesterol-lowering activity. Given the magnitude of the effects of DBR, these findings are promising for clinical implementation of DBR for treating hypercholesterolemia.

Adsorption and desorption characteristics of gradient distributed Bragg reflector porous silicon layers.

PubMed

Um, Sungyong; Lee, Sung Gi; Woo, Hee-Gweon; Cho, Sungdong; Sohn, Honglae

2013-01-01

Adsorption and desorption characteristics of gradient distributed Bragg reflector (DBR) porous silicon (PSi) were investigated under the exposure of organic vapors. Gradient DBR PSi whose average pore size decreased as the lateral distance from the Pt electrode increased was generated by using an asymmetric etching configuration. The reflection resonances were measured as a function of lateral distance from a point closest to the plate Pt electrode to a position on the silicon surface. Two types of gradient DBR PSi (H- and HO-terminated gradient DBR PSi) were used in this study. The detection of volatile organic compounds (VOCs) using the gradient DBR PSi had been achieved. When the vapor of VOCs condensed in the nanopores, the gradient DBR PSi modified with hydrophobic and hydrophilic functionality exhibited different pore adsorption and desorption characteristics.

Fabrication of gradient optical filter containing anisotropic Bragg nanostructure.

PubMed

Cho, Bomin; Um, Sungyong; Woo, Hee-Gweon; Sohn, Honglae

2011-08-01

New gradient optical filters containing asymmetric Bragg structure were prepared from the distributed Bragg reflector (DBR) porous silicon (PSi). Anisotropic DBR PSi displaying a rainbow-colored reflection was generated by using an asymmetric etching configuration. Flexible anisotropic DBR PSi composite films were obtained by casting of polymer solution onto anisotropic DBR PSi thin films. The surface and cross-sectional images images of anisotropic DBR PSi composite films obtained with cold field emission scanning electron microscope indicated that the average pore size and the thickness of porous layer decreased as the lateral distance increased. As lateral distance increased, the reflection resonance shifted to shorter wavelength.

Design and Analysis of Enhanced Modulation Response in Integrated Coupled Cavities DBR Lasers Using Photon-Photon Resonance

DOE PAGES

Bardella, Paolo; Chow, Weng; Montrosset, Ivo

2016-01-08

In the last decades, various solutions have been proposed to increase the modulation bandwidth and consequently the transmission bit rate of integrated semiconductor lasers. In this manuscript we discuss a design procedure for a recently proposed laser structure realized with the integration of two DBR lasers. Design guidelines will be proposed and dynamic small and large signal simulations, calculated using a Finite Difference Traveling Wave numerical simulator, will be performed to confirm the design results and the effectiveness of the analyzed integrated configuration to achieve a direct modulation bandwidth up to 80 GHz

Modelling and Simulation of Single-Phase Series Active Compensator for Power Quality Improvement

NASA Astrophysics Data System (ADS)

Verma, Arun Kumar; Mathuria, Kirti; Singh, Bhim; Bhuvaneshwari, G.

2017-10-01

A single-phase active series compensator is proposed in this work to reduce harmonic currents at the ac mains and to regulate the dc link voltage of a diode bridge rectifier (DBR) that acts as the front end converter for a voltage source inverter feeding an ac motor. This ac motor drive is used in any of the domestic, commercial or industrial appliances. Under fluctuating ac mains voltages, the dc link voltage of the DBR depicts wide variations and hence the ac motor is used at reduced rating as compared to its name-plate rating. The active series compensator proposed here provides dual functions of improving the power quality at the ac mains and regulating the dc link voltage thus averting the need for derating of the ac motor.

Numerical simulation and experimental investigation of GaN-based flip-chip LEDs and top-emitting LEDs.

PubMed

Liu, Xingtong; Zhou, Shengjun; Gao, Yilin; Hu, Hongpo; Liu, Yingce; Gui, Chengqun; Liu, Sheng

2017-12-01

We demonstrate a GaN-based flip-chip LED (FC-LED) with a highly reflective indium-tin oxide (ITO)/distributed Bragg reflector (DBR) ohmic contact. A transparent ITO current spreading layer combined with Ta 2 O 5 /SiO 2 double DBR stacks is used as a reflective p-type ohmic contact in the FC-LED. We develop a strip-shaped SiO 2 current blocking layer, which is well aligned with a p-electrode, to prevent the current from crowding around the p-electrode. Our combined numerical simulation and experimental results revealed that the FC-LED with ITO/DBR has advantages of better current spreading and superior heat dissipation performance compared to top-emitting LEDs (TE-LEDs). As a result, the light output power (LOP) of the FC-LED with ITO/DBR was 7.6% higher than that of the TE-LED at 150 mA, and the light output saturation current was shifted from 130.9  A/cm 2 for the TE-LED to 273.8  A/cm 2 for the FC-LED with ITO/DBR. Owing to the high reflectance of the ITO/DBR ohmic contact, the LOP of the FC-LED with ITO/DBR was 13.0% higher than that of a conventional FC-LED with Ni/Ag at 150 mA. However, because of the better heat dissipation of the Ni/Ag ohmic contact, the conventional FC-LED with Ni/Ag exhibited higher light output saturation current compared to the FC-LED with ITO/DBR.

Using Design-Based Research in Gifted Education

ERIC Educational Resources Information Center

Jen, Enyi; Moon, Sidney; Samarapungavan, Ala

2015-01-01

Design-based research (DBR) is a new methodological framework that was developed in the context of the learning sciences; however, it has not been used very often in the field of gifted education. Compared with other methodologies, DBR is more process-oriented and context-sensitive. In this methodological brief, the authors introduce DBR and…

High-speed directly modulated widely tunable two-section InGaAlAs DBR lasers.

PubMed

Zhou, Daibing; Liang, Song; Zhao, Lingjuan; Zhu, Hongliang; Wang, Wei

2017-02-06

We report widely tunable two-section distributed Bragg reflector (DBR) lasers, which have InGaAlAs multiple quantum wells (MQWs) as the gain material. By butt-jointing InGaAsP, which has a photoluminescence wavelength of 1.4 μm as the material of the DBR section, a wavelength tuning range of 12 nm can be obtained by current injection into the DBR section. The direct modulation bandwidth of the lasers is greater than 10 GHz over the entire wavelength tuning range up to 40°C. Compared with InGaAsP DBR lasers having the same structure, the InGaAlAs lasers have smaller variations in both the threshold current and slope efficiency with the temperature because of the better electron confinement in the InGaAlAs MQWs. Moreover, the DBR-current-induced decreases in the modulation bandwidth and side mode suppression ratio (SMSR) of the optical spectra are notably smaller for the InGaAlAs lasers than for the InGaAsP lasers.

Crystal structure of the Entamoeba histolytica RNA lariat debranching enzyme EhDbr1 reveals a catalytic Zn 2+/Mn 2+ heterobinucleation

DOE PAGES

Ransey, Elizabeth; Paredes, Eduardo; Dey, Sourav K.; ...

2017-05-17

Here, the RNA lariat debranching enzyme, Dbr1, is a metallophosphoesterase that cleaves 2'-5' phosphodiester bonds within intronic lariats. Previous reports have indicated that Dbr1 enzymatic activity is supported by diverse metal ions including Ni 2+, Mn 2+, Mg 2+, Fe 2+, and Zn 2+. While in initial structures of the Entamoeba histolytica Dbr1 only one of the two catalytic metal-binding sites were observed to be occupied (with a Mn 2+ ion), recent structures determined a Zn 2+/Fe 2+ heterobinucleation. We solved a high-resolution X-ray crystal structure (1.8 Å) of the E. histolytica Dbr1 and determined a Zn 2+/Mn 2+ occupancy.more » ICP-AES corroborate this finding, and in vitro debranching assays with fluorescently labeled branched substrates confirm activity.« less

Crystal structure of the Entamoeba histolytica RNA lariat debranching enzyme EhDbr1 reveals a catalytic Zn 2+/Mn 2+ heterobinucleation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ransey, Elizabeth; Paredes, Eduardo; Dey, Sourav K.

Here, the RNA lariat debranching enzyme, Dbr1, is a metallophosphoesterase that cleaves 2'-5' phosphodiester bonds within intronic lariats. Previous reports have indicated that Dbr1 enzymatic activity is supported by diverse metal ions including Ni 2+, Mn 2+, Mg 2+, Fe 2+, and Zn 2+. While in initial structures of the Entamoeba histolytica Dbr1 only one of the two catalytic metal-binding sites were observed to be occupied (with a Mn 2+ ion), recent structures determined a Zn 2+/Fe 2+ heterobinucleation. We solved a high-resolution X-ray crystal structure (1.8 Å) of the E. histolytica Dbr1 and determined a Zn 2+/Mn 2+ occupancy.more » ICP-AES corroborate this finding, and in vitro debranching assays with fluorescently labeled branched substrates confirm activity.« less

Record-level quantum efficiency from a high polarization strained GaAs/GaAsP superlattice photocathode with distributed Bragg reflector

DOE PAGES

Liu, Wei; Chen, Yiqiao; Lu, Wentao; ...

2016-12-19

Photocathodes that provide high polarization and high quantum efficiency (QE) can significantly enhance the physics capabilities of electron accelerators. We report record-level QE from a high-polarization strained GaAs/GaAsP superlattice photocathode fabricated with a Distributed Bragg Reflector (DBR). The DBR photocathode technique enhances the absorption of incident laser light thereby enhancing QE, but as literature suggests, it is very challenging to optimize all of the parameters associated with the fabrication of complicated photocathode structures composed of many distinct layers. Past reports of DBR photocathodes describe high polarization but typically QE of only ~ 1%, which is comparable to QE of highmore » polarization photocathodes grown without a DBR structure. As a result, this work describes a new strained GaAs/GaAsP superlattice DBR photocathode exhibiting polarization of 84% and QE of 6.4%.« less

Record-level quantum efficiency from a high polarization strained GaAs/GaAsP superlattice photocathode with distributed Bragg reflector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wei; Chen, Yiqiao; Lu, Wentao

Photocathodes that provide high polarization and high quantum efficiency (QE) can significantly enhance the physics capabilities of electron accelerators. We report record-level QE from a high-polarization strained GaAs/GaAsP superlattice photocathode fabricated with a Distributed Bragg Reflector (DBR). The DBR photocathode technique enhances the absorption of incident laser light thereby enhancing QE, but as literature suggests, it is very challenging to optimize all of the parameters associated with the fabrication of complicated photocathode structures composed of many distinct layers. Past reports of DBR photocathodes describe high polarization but typically QE of only ~ 1%, which is comparable to QE of highmore » polarization photocathodes grown without a DBR structure. As a result, this work describes a new strained GaAs/GaAsP superlattice DBR photocathode exhibiting polarization of 84% and QE of 6.4%.« less

Numerical and experimental investigation of GaN-based flip-chip light-emitting diodes with highly reflective Ag/TiW and ITO/DBR Ohmic contacts.

PubMed

Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Liu, Yingce; Liu, Mengling; Liu, Zongyuan; Gui, Chengqun; Liu, Sheng

2017-10-30

We demonstrate two types of GaN-based flip-chip light-emitting diodes (FCLEDs) with highly reflective Ag/TiW and indium-tin oxide (ITO)/distributed Bragg reflector (DBR) p-type Ohmic contacts. We show that a direct Ohmic contact to p-GaN layer using pure Ag is obtained when annealed at 600°C in N 2 ambient. A TiW diffusion barrier layer covered onto Ag is used to suppress the agglomeration of Ag and thus maintain high reflectance of Ag during high temperature annealing process. We develop a strip-shaped SiO 2 current blocking layer beneath the ITO/DBR to alleviate current crowding occurring in FCLED with ITO/DBR. Owing to negligibly small spreading resistance of Ag, however, our combined numerical and experimental results show that the FCLED with Ag/TiW has a more favorable current spreading uniformity in comparison to the FCLED with ITO/DBR. As a result, the light output power of FCLED with Ag/TiW is 7.5% higher than that of FCLED with ITO/DBR at 350 mA. The maximum output power of the FCLED with Ag/TiW obtained at 305.6 A/cm 2 is 29.3% larger than that of the FCLED with ITO/DBR obtained at 278.9 A/cm 2 . The improvement appears to be due to the enhanced current spreading and higher optical reflectance provided by the Ag/TiW.

Reflectors and tuning elements for widely-tunable GaAs-based sampled grating DBR lasers

NASA Astrophysics Data System (ADS)

Brox, O.; Wenzel, H.; Della Case, P.; Tawfieq, M.; Sumpf, B.; Weyers, M.; Knigge, A.

2018-02-01

Widely-tunable lasers without moving parts are attractive light sources for sensors in industry and biomedicine. In contrast to InP based sampled grating (SG) distributed Bragg reflector (DBR) diode lasers which are commercially available, shorter wavelength GaAs SG-DBR lasers are still under development. One reason is the difficulty to integrate gratings with coupling coefficients that are high enough for functional grating bursts with lengths below 10 μm. Recently we have demonstrated > 20 nm wide quasi-continuous tuning with a GaAs based SG-DBR laser emitting around 975 nm. Wavelength selective reflectors are realized with SGs having different burst periods for the front and back mirrors. Thermal tuning elements (resistors) which are placed on top of the SG allow the control of the spectral positions of the SG reflector combs and hence to adjust the Vernier mode. In this work we characterize subsections of the developed SG-DBR laser to further improve its performance. We study the impact of two different vertical structures (with vertical far field FWHMs of 41° and 24°) and two grating orders on the coupling coefficient. Gratings with coupling coefficients above 350 cm-1 have been integrated into SG-DBR lasers. We also examine electronic tuning elements (a technique which is typically applied in InP based SG-DBR lasers and allows tuning within nanoseconds) and discuss the limitations in the GaAs material system

Wavelength stabilized DBR high power diode laser using EBL optical confining grating technology

NASA Astrophysics Data System (ADS)

Paoletti, R.; Codato, S.; Coriasso, C.; Gotta, P.; Meneghini, G.; Morello, G.; De Melchiorre, P.; Riva, E.; Rosso, M.; Stano, A.; Gattiglio, M.

2018-02-01

This paper reports a DBR High Power Diode Laser (DBR-HPDL) realization, emitting up to 10W in the 920 nm range. High spectral purity (90% power in about 0.5 nm), and wavelength stability versus injected current (about 5 times more than standard FP laser) candidates DBR-HPDL as a suitable device for wavelength stabilized pump source, and high brightness applications exploiting Wavelength Division Multiplexing. Key design aspect is a multiple-orders Electron Beam Lithography (EBL) optical confining grating, stabilizing on same wafer multiple wavelengths by a manufacturable and reliable technology. Present paper shows preliminary demonstration of wafer with 3 pitches, generating DBRHPDLs 2.5 nm spaced.

Smart particles for noble drug delivery system.

PubMed

Park, Cheolyoung; Kim, Jihoon; Jang, Seunghyun; Woo, Hee-Gweon; Ko, Young Chun; Sohn, Honglae

2010-05-01

Optically encoded smart particles were prepared for noble drug delivery materials. Distributed Bragg reflector (DBR) porous silicon (PSi) was generated by applying a computer-generated pseudo-square wave current waveform. This DBR PSi film was lifted off from the Si substrate and thermally oxidized to convert PSi to porous silicon dioxide (PSD). DBR PSD film was derivatized with 20(S)-Camptothecin (CPT) and fractured by ultrasono-method to give smart particles. DBR PSD smart particles exhibited a sharp photonic band gap in the optical reflectivity spectrum. Optical characteristic of PSD smart particles retained DBR photonic property in aqueous buffer solution. The release of CPT and change of reflection wavelength were measured by UV-vis and reflectance spectrometer, respectively. The intensity of differential peak from reflection resonances of the smart particles was increased with a drug release. The blue shift of reflection peak resulted in the decrease of refractive index of PSD smart particles during the drug release. The concentration of released drug exhibited an linear relationship with a release time.

Design-Based Research (DBR) in Educational Enquiry and Technological Studies: A Version for PhD Students Targeting the Integration of New Technologies and Literacies into Educational Contexts

ERIC Educational Resources Information Center

Abdallah, Mahmoud M. S.; Wegerif, Rupert B.

2014-01-01

This article discusses educational design-based research (DBR) as an emerging paradigm/methodology in educational enquiry that can be used as a mixed-method, problem-oriented research framework, and thus can act as an alternative to other traditional paradigms/methodologies prominent within the Egyptian context of educational enquiry. DBR is often…

Effects of Radiation on Proteasome Function in Prostate Cancer Cells

DTIC Science & Technology

2009-02-01

Figure 3. 10% SDS-PAGE of immunoprecipitated 26S proteasome from PC3 cells extracted with ATP!S instead of ATP. From the left: not irradiated...block the transcription (DBR). Cells were treated with DBR 10 minutes after being exposed to a dose of radiation of 10Gy. The extracts were made at...inhibition. Figure 5. PC3 cells treated with DBR, an inhibitor of polymerase II. Proteins were extracted at different time points and the

High performance organic distributed Bragg reflector lasers fabricated by dot matrix holography.

PubMed

Wan, Wenqiang; Huang, Wenbin; Pu, Donglin; Qiao, Wen; Ye, Yan; Wei, Guojun; Fang, Zongbao; Zhou, Xiaohong; Chen, Linsen

2015-12-14

We report distributed Bragg reflector (DBR) polymer lasers fabricated using dot matrix holography. Pairs of distributed Bragg reflector mirrors with variable mirror separations are fabricated and a novel energy transfer blend consisting of a blue-emitting conjugated polymer and a red-emitting one is spin-coated onto the patterned substrate to complete the device. Under optical pumping, the device emits sing-mode lasing around 622 nm with a bandwidth of 0.41 nm. The working threshold is as low as 13.5 μJ/cm² (~1.68 kW/cm²) and the measured slope efficiency reaches 5.2%. The distributed feedback (DFB) cavity and the DBR cavity resonate at the same lasing wavelength while the DFB laser shows a much higher threshold. We further show that flexible DBR lasers can be conveniently fabricated through the UV-imprinting technique by using the patterned silica substrate as the mold. Dot matrix holography represents a versatile approach to control the number, the size, the location and the orientation of DBR mirrors, thus providing great flexibility in designing DBR lasers.

DBR laser with nondynamic plasma grating formed by focused ion beam implanted dopants

NASA Technical Reports Server (NTRS)

Boenke, Myra M.; Wu, M. C.; Wang, Shyh; Clark, William M., Jr.; Stevens, Eugene H.

1989-01-01

A static plasma grating has been demonstrated experimentally (Wu et al., 1988) in a large-optical-cavity focused-ion-beam-distributed-Bragg-reflector (FIB-DBR) GaAlAs/GaAs laser diode. The grating is formed by implanting stripes of dopants with a focused ion beam. The dopants ionize to form periodic fluctuations in the carrier concentration which, through the Kramers-Kronig relations, form an index grating. A model of the grating strength for optimizaton of the laser design is developed and presented. The computed results show that the coupling coefficient k can be increased by more than an order of magnitude over the 15/cm experimentally. Therefore, FIB-DBR or FIB-distributed-feedback (DFB) lasers with performance comparable to that of conventional DBR (or DFB) lasers can be expected.

Experimental Investigation and Computer Modeling of Optical Switching in Distributed Bragg Reflector and Vertical Cavity Surface Emitting Laser Structures.

DTIC Science & Technology

1995-12-01

of a Molecular Beam Epitaxy (MBE) system prior to growing a Vertical Cavity Surface Emitting Laser ( VCSEL ). VCSEL bistability is discussed later in...addition, optical bistability 1 in the reflectivity of a DBR, as well as in the lasing power, wavelength, and beam divergence of a lasing VCSEL are...Spectral Reflectivity of AlGaAs/AlAs VCSEL Top DBR Mirror Cavity Bottom DBR Mirror Substrate Output Beam Resonance Pump Minimum Stop Band Figure 2. VCSEL

Improved immediate breast reconstruction as a result of oncoplastic multidisciplinary meeting.

PubMed

El Gammal, Mohsen M; Lim, Maria; Uppal, Rajan; Sainsbury, Richard

2017-01-01

The National Institute for Health and Clinical Excellence guidelines recommend that breast reconstruction should be available to all women undergoing mastectomy and discussed at the initial surgical consultation (2002, and updated 2009). The National Mastectomy and Breast Reconstruction Audit (2009) showed that 21% of mastectomy patients underwent immediate breast reconstruction (IBR) and 11% had delayed breast reconstruction (DBR). Breast reconstruction has been shown to have a positive effect on quality of life postmastectomy. This retrospective study investigated the impact of the introduction of a dedicated oncoplastic multidisciplinary meeting (OP MDM) on our unit's breast reconstruction rate. A retrospective analysis of 229 women who underwent mastectomy, of whom 81 (35%) underwent breast reconstruction between April 2014 and March 2016. Data were analyzed before and after introduction of OP MDM in April 2015. Data on patient age, type of surgery (mastectomy only, mastectomy and reconstruction), timing of reconstruction (IBR, DBR), and type of reconstruction (implant, autologous) were collected. Between April 2015 and March 2016, following establishment of OP multidisciplinary team in April 2015, of the 120 patients who had mastectomy, 50 (42%) underwent breast reconstruction with 78% (39/50) choosing IBR (56% implant reconstruction and 22% autologous). Compared to the period between April 2014 and March 2015 preceding the OP MDM, of 109 patients who underwent mastectomy, only 31 (28%) had breast reconstruction with 64% (20/31) choosing IBR (45% implant reconstruction and 19% autologous). The rate of DBR was lower, 22% (11/50), following OP MDM compared to 35% (11/31) before OP MDM. There has been an increased uptake of breast reconstruction surgery from 28% to 42%. The biggest impact was on those opting for the immediate type reconstruction option (78%). The OP MDM has significantly contributed to this increased rate of reconstruction.

Observation of Significant Quantum Efficiency Enhancement from a Polarized Photocathode with Distributed Bragg Reflector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shukui; Poelker, Matthew; Stutzman, Marcy L.

2015-09-01

Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we presentmore » recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.« less

A comparative study of thermal characteristics of GaN-based VCSELs with three different typical structures

NASA Astrophysics Data System (ADS)

Mei, Yang; Xu, Rong-Bin; Xu, Huan; Ying, Lei-Ying; Zheng, Zhi-Wei; Zhang, Bao-Ping; Li, Mo; Zhang, Jian

2018-01-01

Thermal characteristics of GaN-based vertical cavity surface emitting lasers (VCSELs) with three typical structures were investigated both theoretically and experimentally. The simulation results based on a steady state quasi three-dimensional cylindrical model show that the thermal resistance (R th) is affected by cavity length, mesa size, as well as the bottom distributed Bragg reflector (DBR) size, and the detail further depends on different structures. Among different devices, GaN VCSEL with a hybrid cavity formed by one nitride bottom DBR and another dielectric top DBR is featured with lower R th, which is meanwhile affected strongly by the materials of the epitaxial bottom DBR. The main issues affecting the thermal dissipation in VCSELs with double dielectric DBRs are the bottom dielectric DBR and the dielectric current-confinement layer. To validate the simulation results, GaN-based VCSEL bonded on a copper plate was fabricated. R th of this device was measured and the results agreed well with the simulation. This work provides a better understanding of the thermal characteristics of GaN-based VCSELs and is useful in optimizing the structure design and improving the device performance.

Magnetic field sensor based on the Ampere's force using dual-polarization DBR fiber laser

NASA Astrophysics Data System (ADS)

Yao, Shuang; Zhang, Yang; Guan, Baiou

2015-08-01

A novel magnetic field sensor using distributed Bragg reflector (DBR) fiber laser by Ampere's force effect is proposed and experimentally demonstrated. The key sensing element, that is the dual-polarization DBR fiber laser, is fixed on the middle part of two copper plates which carry the current. Ampere's force is applied onto the coppers due to an external magnetic field generated by a DC solenoid. Thus, the lateral force from the coppers is converted to a corresponding beat frequency signal shift produced by the DBR laser. The electric current sensing is also realized by the same configuration and same principle simultaneously in an intuitive manner. Good agreement between the theory calculation and the experimental results is obtained, which shows a good linearity. This sensor's sensitivity to the magnetic field and to the electric current finally reaches ~258.92 kHz/mT and ~1.08727 MHz/A, respectively.

A contact vibration measurement sensor based on a distributed Bragg reflector fiber laser

NASA Astrophysics Data System (ADS)

Jin, Jie; Fang, Gan; Lyu, Chengang; Zhang, Shuai

2017-12-01

A new contact method to measure vibrations with a frequency range of about 30-110 Hz by a distributed Bragg reflector (DBR) fiber laser sensor, based on a beat frequency modulation, has been proposed. In order to demonstrate the plausibility for a DBR fiber sensor to detect vibrations lower than 110 Hz without any complex structures, it is encapsulated in a rectangular slice composed of an epoxy resin glue, with a Young’s modulus of about 2.9 GPa. In experiments, the packaged DBR fiber sensor is placed on a vibration platform to sense the vibration, with a commercial magnet-electrical vibration velocity transducer as a reference. Experimental results indicate that the single DBR fiber laser is able to measure the low-frequency vibration with a few tens of Hertz and several microns of amplitude, offering potential for a low-frequency vibration measurement.

On the tunability of quality-factor for optical Tamm plasmon modes

NASA Astrophysics Data System (ADS)

Kumar, Samir; Das, Ritwick

2017-09-01

We present a comprehensive investigation to ascertain the impact of gold and silver films on modifying the quality-factor (Q-factor) of optical Tamm-plasmon (OTP) resonance in a metal-distributed Bragg reflector (M-DBR) geometry. Here, OTP mode is excited using direct incidence of white-light-source at normal incidence as well as oblique incidence on M-DBR geometry. The lifetime of OTP in gold and silver deposited films on DBR mirror was determined from OTP resonance linewidth. The lifetime and the Q-factor of OTP modes are found to depend on DBR bilayers, metal film thickness as well as on different plasmon active metals. This finding would facilitate tuning the Q-factor and consequently, the lifetime of OTP modes for various applications in all-optical switches and modulators. In addition, we discuss the spectral characteristics of OTP modes excited using normal and oblique incident of source.

Dispersed bubble reactor for enhanced gas-liquid-solids contact and mass transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

An apparatus to promote gas-liquid contact and facilitate enhanced mass transfer. The dispersed bubble reactor (DBR) operates in the dispersed bubble flow regime to selectively absorb gas phase constituents into the liquid phase. The dispersion is achieved by shearing the large inlet gas bubbles into fine bubbles with circulating liquid and additional pumped liquid solvent when necessary. The DBR is capable of handling precipitates that may form during absorption or fine catalysts that may be necessary to promote liquid phase reactions. The DBR can be configured with multistage counter current flow sections by inserting concentric cylindrical sections into the risermore » to facilitate annular flow. While the DBR can absorb CO.sub.2 in liquid solvents that may lead to precipitates at high loadings, it is equally capable of handling many different types of chemical processes involving solids (precipitates/catalysts) along with gas and liquid phases.« less

A new scale for the assessment of conjunctival bulbar redness.

PubMed

Macchi, Ilaria; Bunya, Vatinee Y; Massaro-Giordano, Mina; Stone, Richard A; Maguire, Maureen G; Zheng, Yuanjie; Chen, Min; Gee, James; Smith, Eli; Daniel, Ebenezer

2018-06-05

Current scales for assessment of bulbar conjunctival redness have limitations for evaluating digital images. We developed a scale suited for evaluating digital images and compared it to the Validated Bulbar Redness (VBR) scale. From a digital image database of 4889 color corrected bulbar conjunctival images, we identified 20 images with varied degrees of redness. These images, ten each of nasal and temporal views, constitute the Digital Bulbar Redness (DBR) scale. The chromaticity of these images was assessed with an established image processing algorithm. Using 100 unique, randomly selected images from the database, three trained, non-physician graders applied the DBR scale and printed VBR scale. Agreement was assessed with weighted Kappa statistics (K w ). The DBR scale scores provide linear increments of 10 from 10-100 when redness is measured objectively with an established image processing algorithm. Exact agreement of all graders was 38% and agreement with no more than a difference of ten units between graders was 91%. K w for agreement between any two graders ranged from 0.57 to 0.73 for the DBR scale and from 0.38 to 0.66 for the VBR scale. The DBR scale allowed direct comparison of digital to digital images, could be used in dim lighting, had both temporal and nasal conjunctival reference images, and permitted viewing reference and test images at the same magnification. The novel DBR scale, with its objective linear chromatic steps, demonstrated improved reproducibility, fewer visualization artifacts and improved ease of use over the VBR scale for assessing conjunctival redness. Copyright © 2018. Published by Elsevier Inc.

Integrated high-order surface diffraction gratings for diode lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zolotarev, V V; Leshko, A Yu; Pikhtin, N A

2015-12-31

High-order surface diffraction gratings acting as a distributed Bragg reflector (DBR) in mesa stripe semiconductor lasers (λ = 1030 nm) have been studied theoretically and experimentally. Higher order interfering radiation modes (IRMs), which propagate off the plane of the waveguide, have been shown to have a crucial effect on the reflection and transmission spectra of the DBR. The decrease in the reflectivity of the DBR in response to the increase in the diffraction efficiency of these modes may reach 80% and more. According to theoretical analysis results, the intensity of the higher order IRMs is determined by the geometry ofmore » the DBR groove profile. Experimental data demonstrate that the noncavity modes are responsible for parasitic light leakage losses in the laser cavity. It has been shown that, in the case of nonoptimal geometry of the grating groove profile, the overall external differential quantum efficiency of the parasitic laser emission may exceed 45%, which is more than half of the laser output power. The optimal geometry of the DBR groove profile is trapezoidal, with the smallest possible lower base. Experimental evidence has been presented that this geometry considerably reduces the power of the higher order IRMs and minimises the parasitic light leakage loss. (lasers)« less

InGaN Light-Emitting Diodes with an Embedded Nanoporous GaN Distributed Bragg Reflectors.

PubMed

Shiu, Guo-Yi; Chen, Kuei-Ting; Fan, Feng-Hsu; Huang, Kun-Pin; Hsu, Wei-Ju; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

2016-07-01

InGaN light emitting diodes (LED) structure with an embedded 1/4λ-stack nanoporous-GaN/undoped-GaN distributed Bragg reflectors (DBR) structure have been demonstrated. Si-heavily doped GaN epitaxial layers (n(+)-GaN) in the 12-period n(+)-GaN/u-GaN stack structure are transformed into low refractive index nanoporous GaN structure through the doping-selective electrochemical wet etching process. The central wavelength of the nanoporous DBR structure was located at 442.3 nm with a 57 nm linewidth and a 97.1% peak reflectivity. The effective cavity length (6.0λ), the effective penetration depth (278 nm) in the nanoporous DBR structure, and InGaN active layer matching to Fabry-Pérot mode order 12 were observed in the far-field photoluminescence radiative spectra. High electroluminescence emission intensity and line-width narrowing effect were measured in the DBR-LED compared with the non-treated LED structure. Non-linear emission intensity and line-width reducing effect, from 11.8 nm to 0.73 nm, were observed by increasing the laser excited power. Resonant cavity effect was observed in the InGaN LED with bottom nanoporous-DBR and top GaN/air interface.

InGaN Light-Emitting Diodes with an Embedded Nanoporous GaN Distributed Bragg Reflectors

PubMed Central

Shiu, Guo-Yi; Chen, Kuei-Ting; Fan, Feng-Hsu; Huang, Kun-Pin; Hsu, Wei-Ju; Dai, Jing-Jie; Lai, Chun-Feng; Lin, Chia-Feng

2016-01-01

InGaN light emitting diodes (LED) structure with an embedded 1/4λ-stack nanoporous-GaN/undoped-GaN distributed Bragg reflectors (DBR) structure have been demonstrated. Si-heavily doped GaN epitaxial layers (n+-GaN) in the 12-period n+-GaN/u-GaN stack structure are transformed into low refractive index nanoporous GaN structure through the doping-selective electrochemical wet etching process. The central wavelength of the nanoporous DBR structure was located at 442.3 nm with a 57 nm linewidth and a 97.1% peak reflectivity. The effective cavity length (6.0λ), the effective penetration depth (278 nm) in the nanoporous DBR structure, and InGaN active layer matching to Fabry-Pérot mode order 12 were observed in the far-field photoluminescence radiative spectra. High electroluminescence emission intensity and line-width narrowing effect were measured in the DBR-LED compared with the non-treated LED structure. Non-linear emission intensity and line-width reducing effect, from 11.8 nm to 0.73 nm, were observed by increasing the laser excited power. Resonant cavity effect was observed in the InGaN LED with bottom nanoporous-DBR and top GaN/air interface. PMID:27363290

The activity of the artemisinic aldehyde Δ11(13) reductase promoter is important for artemisinin yield in different chemotypes of Artemisia annua L.

PubMed

Yang, Ke; Monfared, Sajad Rashidi; Monafared, Rashidi Sajad; Wang, Hongzhen; Lundgren, Anneli; Brodelius, Peter E

2015-07-01

The artemisinic aldehyde double bond reductase (DBR2) plays an important role in the biosynthesis of the antimalarial artemisinin in Artemisia annua. Artemisinic aldehyde is reduced into dihydroartemisinic aldehyde by DBR2. Artemisinic aldehyde can also be oxidized by amorpha-4,11-diene 12-hydroxylase and/or aldehyde dehydrogenase 1 to artemisinic acid, a precursor of arteannuin B. In order to better understand the effects of DBR2 expression on the flow of artemisinic aldehyde into either artemisinin or arteannuin B, we determined the content of dihydroartemisinic aldehyde, artemisinin, artemisinic acid and arteannuin B content of A. annua varieties sorted into two chemotypes. The high artemisinin producers (HAPs), which includes the '2/39', 'Chongqing' and 'Anamed' varieties, produce more artemisinin than arteannuin B; the low artemisinin producers (LAPs), which include the 'Meise', 'Iran#8', 'Iran#14', 'Iran#24' and 'Iran#47' varieties, produce more arteannuin B than artemisinin. Quantitative PCR showed that the relative expression of DBR2 was significantly higher in the HAP varieties. We cloned and sequenced the promoter of the DBR2 gene from varieties of both the LAP and the HAP groups. There were deletions/insertions in the region just upstream of the ATG start codon in the LAP varities, which might be the reason for the different promoter activities of the HAP and LAP varieties. The relevance of promoter variation, DBR2 expression levels and artemisinin biosynthesis capabilities are discussed and a selection method for HAP varieties with a DNA marker is suggested. Furthermore, putative cis-acting regulatory elements differ between the HAP and LAP varieties.

Ultraviolet GaN photodetectors on Si via oxide buffer heterostructures with integrated short period oxide-based distributed Bragg reflectors and leakage suppressing metal-oxide-semiconductor contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szyszka, A., E-mail: szyszka@ihp-microelectronics.com, E-mail: adam.szyszka@pwr.wroc.pl; Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw; Lupina, L.

2014-08-28

Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y{sub 2}O{sub 3} films is detected under the applied thermal growth budget. Asmore » revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.« less

Coupling to Tamm-plasmon-polaritons: dependence on structural parameters

NASA Astrophysics Data System (ADS)

Kumari, Anupa; Kumar, Samir; Shukla, Mukesh Kumar; Kumar, Govind; Sona Maji, Partha; Vijaya, R.; Das, Ritwick

2018-06-01

Tamm plasmon-polaritons (TPPs), formed at the interface of a plasmon-active metal and a distributed Bragg reflector (DBR), are characterized by sharp resonances in the reflection spectrum. The features of these sharp TPP resonances are primarily dictated by the structural parameters as well as by the nature of materials of the constituent DBR and metal. In the present investigation, we experimentally and theoretically analyze the role played by the DBR parameters and the metal layer thickness in determining the efficiency of TPP-mode excitation using plane waves. The findings reveal that the minimum in the reflection spectrum depicting the TPP resonance is strongly influenced by the thickness of plasmon-active metal film as well as the number of DBR unit cells. In fact, there exists an optimum combination of the geometrical parameters for achieving a maximum coupling to TPP modes. A brief theoretical analysis elucidating the underlying mechanism behind such observations is also presented so as to optimally design TPP-based architectures for different applications.

High-power and brightness laser diode modules using new DBR chips

NASA Astrophysics Data System (ADS)

Yu, Hao; Riva, Martina; Rossi, Giammarco; Braglia, Andrea; Perrone, Guido

2018-02-01

The paper reports on the design, manufacturing and preliminary characterization of a new family of compact and high beam quality multi-emitter laser diode modules capable of delivering up to over 400W in a 135/0.15 fiber. The layout exploits a proprietary architecture and is based on innovative narrow linewidth high-power DBR chips, properly combined through spatial, polarization and wavelength multiplexing. The intrinsic wavelength-stabilization of these DBR chips allows the use of the developed modules not only for direct-diode material processing but also in pump sources for ytterbium-doped fiber lasers without the need of external stabilization devices.

Diffraction limited 1064nm monolithic DBR-master oscillator power amplifier with more than 7W output power

NASA Astrophysics Data System (ADS)

Zink, Christof; Maaβdorf, André; Fricke, Jörg; Ressel, Peter; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

2018-02-01

High brightness diode lasers with a spectrally narrowband emission, several watts of output power with an almost diffraction limited beam quality are requested light sources for several applications. In this work, a monolithic master oscillator power amplifier will be presented. The resonator of the master oscillator is formed by a high-reflection DBR grating on the rear side and an internal DBR mirror. Its power is amplified in a ridge waveguide followed by a tapered section. The monolithic MOPA provides over 7 W at 1064 nm with a narrow spectral emission width below 20 pm and an almost diffraction limited beam.

Temporary abdominal closure and delayed biliary reconstruction due to massive bleeding in patients undergoing liver transplantation: an old trick in a new indication

PubMed Central

Komorowski, Andrzej L.; Li, Wei‐Feng; Millan, Carlos A.; Huang, Tun‐Sung; Yong, Chee‐Chien; Lin, Tsan‐Shiun; Lin, Ting‐Lung; Jawan, Bruno; Chen, Chao‐Long

2016-01-01

Abstract Background Massive bleeding during liver transplantation (LT) is difficult to manage surgical event. Perihepatic packing (PP) and temporary abdominal closure (TAC) with delayed biliary reconstruction (DBR) can be applied in these circumstances. Method A prospective database of LT in a major transplant center was analyzed to identify patients with massive uncontrollable bleeding during LT that was resolved by PP, TAC, and DBR. Results From January 2009 to July 2013, 20 (3.6%) of 547 patients who underwent LT underwent DBR. Mean intraoperative blood loss was 20,500 ml at the first operation. The DBR was performed with a mean of 55.2 h (16–110) after LT. Biliary reconstruction included duct‐to‐duct (n = 9) and hepatico‐jejunostomy (n = 11). Complications occurred in eight patients and included portal vein thrombosis, cholangitis, severe bacteremia, pneumonia. There was one in‐hospital death. In the follow‐up of 18 to 33 months we have seen one patient died 9 months after transplantation. The remaining 18 patients are alive and well. Conclusions In case of massive uncontrollable bleeding and bowel edema during LT, the combined procedures of PP, TAC, and DBR offer an alternatively surgical option to solve the tough situation. PMID:26692574

A DBR Framework for Designing Mobile Virtual Reality Learning Environments

ERIC Educational Resources Information Center

Cochrane, Thomas Donald; Cook, Stuart; Aiello, Stephen; Christie, Duncan; Sinfield, David; Steagall, Marcus; Aguayo, Claudio

2017-01-01

This paper proposes a design based research (DBR) framework for designing mobile virtual reality learning environments. The application of the framework is illustrated by two design-based research projects that aim to develop more authentic educational experiences and learner-centred pedagogies in higher education. The projects highlight the first…

Interferometric nanoporous anodic alumina photonic coatings for optical sensing

NASA Astrophysics Data System (ADS)

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Wang, Changhai; Li, Junsheng; Losic, Dusan

2015-04-01

Herein, we present a systematic study on the development, optical optimization and sensing applicability of colored photonic coatings based on nanoporous anodic alumina films grown on aluminum substrates. These optical nanostructures, so-called distributed Bragg reflectors (NAA-DBRs), are fabricated by galvanostatic pulse anodization process, in which the current density is altered in a periodic manner in order to engineer the effective medium of the resulting photonic coatings. As-prepared NAA-DBR photonic coatings present brilliant interference colors on the surface of aluminum, which can be tuned at will within the UV-visible spectrum by means of the anodization profile. A broad library of NAA-DBR colors is produced by means of different anodization profiles. Then, the effective medium of these NAA-DBR photonic coatings is systematically assessed in terms of optical sensitivity, low limit of detection and linearity by reflectometric interference spectroscopy (RIfS) in order to optimize their nanoporous structure toward optical sensors with enhanced sensing performance. Finally, we demonstrate the applicability of these photonic nanostructures as optical platforms by selectively detecting gold(iii) ions in aqueous solutions. The obtained results reveal that optimized NAA-DBR photonic coatings can achieve an outstanding sensing performance for gold(iii) ions, with a sensitivity of 22.16 nm μM-1, a low limit of detection of 0.156 μM (i.e. 30.7 ppb) and excellent linearity within the working range (0.9983).Herein, we present a systematic study on the development, optical optimization and sensing applicability of colored photonic coatings based on nanoporous anodic alumina films grown on aluminum substrates. These optical nanostructures, so-called distributed Bragg reflectors (NAA-DBRs), are fabricated by galvanostatic pulse anodization process, in which the current density is altered in a periodic manner in order to engineer the effective medium of the resulting photonic coatings. As-prepared NAA-DBR photonic coatings present brilliant interference colors on the surface of aluminum, which can be tuned at will within the UV-visible spectrum by means of the anodization profile. A broad library of NAA-DBR colors is produced by means of different anodization profiles. Then, the effective medium of these NAA-DBR photonic coatings is systematically assessed in terms of optical sensitivity, low limit of detection and linearity by reflectometric interference spectroscopy (RIfS) in order to optimize their nanoporous structure toward optical sensors with enhanced sensing performance. Finally, we demonstrate the applicability of these photonic nanostructures as optical platforms by selectively detecting gold(iii) ions in aqueous solutions. The obtained results reveal that optimized NAA-DBR photonic coatings can achieve an outstanding sensing performance for gold(iii) ions, with a sensitivity of 22.16 nm μM-1, a low limit of detection of 0.156 μM (i.e. 30.7 ppb) and excellent linearity within the working range (0.9983). Electronic supplementary information (ESI) available: The Supporting Information file provides further information about real-time monitoring of ΔOTeff with changes in the refractive index of the medium filling the nanopores, demonstration of visual red shift in a NAA-DBR sample after infiltration with isopropanol and calculations of linearity (R2) for each NAA-DBR coating. See DOI: 10.1039/c5nr00369e

Mutual Injection Locking of Monolithically Integrated Coupled-Cavity DBR Lasers

DOE PAGES

Tauke-Pedretti, Anna; Vawter, G. Allen; Skogen, Erik J.; ...

2011-07-01

We present a photonic integrated circuit (PIC) composed of two strongly coupled distributed Bragg reflector (DBR) lasers. This PIC utilizes the dynamics of mutual injection locking to increase the relaxation resonance frequency from 3 GHz to beyond 30 GHz. Mutual injection-locking and external injection-locking operation are then compared.

Bridging Professional Teacher Knowledge for Science and Literary Integration via Design-Based Research

ERIC Educational Resources Information Center

Fazio, Xavier; Gallagher, Tiffany L.

2018-01-01

We offer insights for using design-based research (DBR) as a model for constructing professional development that supports curriculum and instructional knowledge regarding science and literacy integration. We spotlight experiences in the DBR process from data collected from a sample of four elementary teachers. Findings from interviews, focus…

A Proposed Theory Seeded Methodology for Design Based Research into Effective Use of MUVES in Vocational Education Contexts

ERIC Educational Resources Information Center

Cochrane, Todd; Davis, Niki; Morrow, Donna

2013-01-01

A methodology for design based research (DBR) into effective development and use of Multi-User Virtual Environments (MUVE) in vocational education is proposed. It blends software development with DBR with two theories selected to inform the methodology. Legitimate peripheral participation LPP (Lave & Wenger, 1991) provides a filter when…

Applying a Conceptual Design Framework to Study Teachers' Use of Educational Technology

ERIC Educational Resources Information Center

Holmberg, Jörgen

2017-01-01

Theoretical outcomes of design-based research (DBR) are often presented in the form of local theory design principles. This article suggests a complementary theoretical construction in DBR, in the form of a "design framework" at a higher abstract level, to study and inform educational design with ICT in different situated contexts.…

Using Design-Based Research in Informal Environments

ERIC Educational Resources Information Center

Reisman, Molly

2008-01-01

Design-Based Research (DBR) has been a tool of the learning sciences since the early 1990s, used as a way to improve and study learning environments. Using an iterative process of design with the goal of reining theories of learning, researchers and educators now use DBR seek to identify "how" to make a learning environment work. They then draw…

Systematic Review of Design-Based Research Progress: Is a Little Knowledge a Dangerous Thing?

ERIC Educational Resources Information Center

McKenney, Susan; Reeves, Thomas C.

2013-01-01

Sufficient attention and resources have been allocated to design-based research (DBR) to warrant review concerning if and how its potential has been realized. Because the DBR literature clearly indicates that this type of research strives toward both the development of an intervention to address a problem in practice and empirical investigation…

Integration of hybrid silicon lasers and electroabsorption modulators.

PubMed

Sysak, Matthew N; Anthes, Joel O; Bowers, John E; Raday, Omri; Jones, Richard

2008-08-18

We present an integration platform based on quantum well intermixing for multi-section hybrid silicon lasers and electroabsorption modulators. As a demonstration of the technology, we have fabricated discrete sampled grating DBR lasers and sampled grating DBR lasers integrated with InGaAsP/InP electroabsorption modulators. The integrated sampled grating DBR laser-modulators use the as-grown III-V bandgap for optical gain, a 50 nm blue shifted bandgap for the electrabosprtion modulators, and an 80 nm blue shifted bandgap for low loss mirrors. Laser continuous wave operation up to 45 ?C is achieved with output power >1.0 mW and threshold current of <50 mA. The modulator bandwidth is >2GHz with 5 dB DC extinction.

Fabrication and characterization of TiO2/SiO2 based Bragg reflectors for light trapping applications

NASA Astrophysics Data System (ADS)

Dubey, R. S.; Ganesan, V.

Distributed Bragg reflectors (DBRs) have received an intensive attention due to their increasing demand in optoelectronic and photonic devices. Such reflectors are capable to prohibit the light propagation within the specified wavelength range of interest. In this paper, we present the fabrication of TiO2/SiO2 stacks based Bragg reflectors by using a simple and in-expensive sol-gel spin coating technique. The prepared single-layer thin films of TiO2 and SiO2 onto glass substrates were characterized for their optical constants. By tuning the process parameters, one-seven DBR stacks of TiO2/SiO2 were prepared. The corresponding shift of the Bragg reflection peak was observed with the increased number of DBR stacks and as much as about 90% reflectance is observed from the 7DBR stacks. The experimentally measured reflectance was compared with the simulated one, which showed good in agreement. FESEM measurement has confirmed the formation of bright and dark strips of TiO2 and SiO2 films with their thicknesses 80 and 115 nm respectively. The simulation study was explored to a design of thin film silicon solar cell using 7DBR stacks. An enhancement in light absorption in the visible wavelength range is observed which coincides with the experimental result of the reflectance. The use of DBR at the bottom of the solar cell could felicitate the better light harvesting with the occurrence of Fabry-Perot resonances in the absorbing layer.

Mechanism of synergistic DNA damage induced by the hydroquinone metabolite of brominated phenolic environmental pollutants and Cu(II): Formation of DNA-Cu complex and site-specific production of hydroxyl radicals.

PubMed

Shao, Bo; Mao, Li; Qu, Na; Wang, Ya-Fen; Gao, Hui-Ying; Li, Feng; Qin, Li; Shao, Jie; Huang, Chun-Hua; Xu, Dan; Xie, Lin-Na; Shen, Chen; Zhou, Xiang; Zhu, Ben-Zhan

2017-03-01

2,6-Dibromohydroquinone (2,6-DBrHQ) has been identified as an reactive metabolite of many brominated phenolic environmental pollutants such as tetrabromobisphenol-A (TBBPA), bromoxynil and 2,4,6-tribromophenol, and was also found as one of disinfection byproducts in drinking water. In this study, we found that the combination of 2,6-DBrHQ and Cu(II) together could induce synergistic DNA damage as measured by double strand breakage in plasmid DNA and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation, while either of them alone has no effect. 2,6-DBrHQ/Cu(II)-induced DNA damage could be inhibited by the Cu(I)-specific chelating agent bathocuproine disulfonate and catalase, but not by superoxide dismutase, nor by the typical hydroxyl radical (•OH) scavengers such as DMSO and mannitol. Interestingly, we found that Cu(II)/Cu(I) could be combined with DNA to form DNA-Cu(II)/Cu(I) complex by complementary application of low temperature direct ESR, circular dichroism, cyclic voltammetry and oxygen consumption methods; and the highly reactive •OH were produced synergistically by DNA-bound-Cu(I) with H 2 O 2 produced by the redox reactions between 2,6-DBrHQ and Cu(II), which then immediately attack DNA in a site-specific manner as demonstrated by both fluorescent method and by ESR spin-trapping studies. Further DNA sequencing investigations provided more direct evidence that 2,6-DBrHQ/Cu(II) caused preferential cleavage at guanine, thymine and cytosine residues. Based on these data, we proposed that the synergistic DNA damage induced by 2,6-DBrHQ/Cu(II) might be due to the synergistic and site-specific production of •OH near the binding site of copper and DNA. Our findings may have broad biological and environmental implications for future research on the carcinogenic polyhalogenated phenolic compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Single-mode 140 nm swept light source realized by using SSG-DBR lasers

NASA Astrophysics Data System (ADS)

Fujiwara, N.; Yoshimura, R.; Kato, K.; Ishii, H.; Kano, F.; Kawaguchi, Y.; Kondo, Y.; Ohbayashi, K.; Oohashi, H.

2008-02-01

We demonstrate a single-mode and fast wavelength swept light source by using Superestrucuture grating distributed Bragg reflector (SSG-DBR) lasers for use in optical frequency-domain reflectometry optical coherence tomography. The SSG-DBR lasers provide single-mode operation resulting in high coherency. Response of the wavelength tuning is very fast; several nanoseconds, but there was an unintentional wavelength drift resulting from a thermal drift due to injecting tuning current. The dri1ft unfortunately requires long time to converge; more than a few milliseconds. For suppressing the wavelength drift, we introduced Thermal Drift Compensation mesa (TDC) parallel to the laser mesa with the spacing of 20 μm. By controlling TDC current to satisfy the total electric power injected into both the laser mesa and the TDC mesa, the thermal drift can be suppressed. In the present work, we fabricated 4 wavelength's kinds of SSG-DBR laser, which covers respective wavelength band; S-band (1496-1529 nm), C-band (1529-1564 nm), L --band (1564-1601 nm), and L +-band (1601-1639). We set the frequency channel of each laser with the spacing 6.25 GHz and 700 channels. The total frequency channel number is 2800 channels (700 ch × 4 lasers). We simultaneously operated the 4 lasers with a time interval of 500 ns/channel. A wavelength tuning range of more than 140 nm was achieved within 350 μs. The output power was controlled to be 10 mW for all channels. A single-mode, accurate, wide, and fast wavelength sweep was demonstrated with the SSG-DBR lasers having TDC mesa structure for the first time.

Electrical investigations of hybrid OLED microcavity structures with novel encapsulation methods

NASA Astrophysics Data System (ADS)

Meister, Stefan; Brückner, Robert; Fröb, Hartmut; Leo, Karl

2016-04-01

An electrical driven organic solid state laser is a very challenging goal which is so far well beyond reach. As a step towards realization, we monolithically implemented an Organic Light Emitting Diode (OLED) into a dielectric, high quality microcavity (MC) consisting of two Distributed Bragg Reectors (DBR). In order to account for an optimal optical operation, the OLED structure has to be adapted. Furthermore, we aim to excite the device not only electrically but optically as well. Different OLED structures with an emission layer consisting of Alq3:DCM (2 wt%) were investigated. The External Quantum Efficiencies (EQE) of this hybrid structures are in the range of 1-2 %, as expected for this material combination. Including metal layers into a MC is complicated and has a huge impact on the device performance. Using Transfer-Matrix-Algorithm (TMA) simulations, the best positions for the metal electrodes are determined. First, the electroluminescence (EL) of the adjusted OLED structure on top of a DBR is measured under nitrogen atmosphere. The modes showed quality factors of Q = 60. After the deposition of the top DBR, the EL is measured again and the quality factors increased up to Q = 600. Considering the two 25-nm-thick-silver contacts a Q-factor of 600 is very high. The realization of a suitable encapsulation method is important. Two approaches were successfully tested. The first method is based on the substitution of a DBR layer with a layer produced via Atomic Layer Deposition (ALD). The second method uses a 0.15-mm-thick cover glass glued on top of the DBR with a 0.23-μm-thick single-component glue layer. Due to the working encapsulation, it is possible to investigate the sample under ambient conditions.

High performance GaN-based LEDs on patterned sapphire substrate with patterned composite SiO2/Al2O3 passivation layers and TiO2/Al2O3 DBR backside reflector.

PubMed

Guo, Hao; Zhang, Xiong; Chen, Hongjun; Zhang, Peiyuan; Liu, Honggang; Chang, Hudong; Zhao, Wei; Liao, Qinghua; Cui, Yiping

2013-09-09

GaN-based light-emitting diodes (LEDs) on patterned sapphire substrate (PSS) with patterned composite SiO(2)/Al(2)O(3) passivation layers and TiO(2)/Al(2)O(3) distributed Bragg reflector (DBR) backside reflector have been proposed and fabricated. Highly passivated Al(2)O(3) layer deposited on indium tin oxide (ITO) layer with excellent uniformity and quality has been achieved with atomic layer deposition (ALD) technology. With a 60 mA current injection, an enhancement of 21.6%, 59.7%, and 63.4% in the light output power (LOP) at 460 nm wavelength was realized for the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers, the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers and Ag mirror + 3-pair TiO(2)/SiO(2) DBR backside reflector, and the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layer and Ag mirror + 3-pair ALD-grown TiO(2)/Al(2)O(3) DBR backside reflector as compared with the conventional LED only with a single SiO(2) passivation layer, respectively.

All-optical clock recovery for 100 Gb/s RZ-OOK signal after 25km transmission using a dual-mode beating DBR laser

NASA Astrophysics Data System (ADS)

Yu, Liqiang; Pan, Biwei; Lu, Dan; Zhao, Lingjuan

2014-11-01

All-optical clock recovery (AOCR) for 100 Gb/s RZ-OOK signal is demonstrated by using a dualmode beating DBR laser. Based on the injection-locking of the DBR (distributed Bragg reflector) laser, a 100-GHz optical clock is recovered. Timing jitter (<1 ps) derived from both phase noise and power fluctuation is measured by an optical sampling oscilloscope (OSO). Furthermore, clock recovery is also realized for the 100 Gb/s signal after 25 km transmission. After the 25-km SMF (5- dB loss) transmission, the signal-to-noise ratio (SNR) of the signal drops from 18 dB to 5.2 dB. The dependence of the timing jitter on the input power is investigated. The lowest timing jitter of 665 fs is realized when the input power is 3 dBm.

Suspended light-emitting diode featuring a bottom dielectric distributed Bragg reflector

NASA Astrophysics Data System (ADS)

Cai, Wei; Wang, Wei; Zhu, Bingcheng; Gao, Xumin; Zhu, Guixia; Yuan, Jialei; Wang, Yongjin

2018-01-01

Here, we propose, fabricate and characterize the light manipulation of a suspended-membrane InGaN/GaN multiple-quantum-well light-emitting diode (MQW-LED) with a dielectric distributed Bragg reflector (DBR) positioned at the bottom, implemented on a GaN-on-silicon platform. Silicon removal is conducted to obtain the suspended MQW-LED architecture, and back wafer thinning of the epitaxial film is performed to improve the device performance. A 6-pair SiO2/Ta2O5 DBR is deposited on the backside to manipulate the emitted light. The experimental results demonstrate that the bottom dielectric DBR exhibits high reflectivity and distinctly changes the light emission, which are consistent with the performed simulation results. This work represents a significant step towards the realization of inexpensive, electrically driven and simply fabricated GaN VCSELs for potential use in number of applications.

Theoretical modeling and experiments on a DBR waveguide laser fabricated by the femtosecond laser direct-write technique.

PubMed

Duan, Yuwen; McKay, Aaron; Jovanovic, Nemanja; Ams, Martin; Marshall, Graham D; Steel, M J; Withford, Michael J

2013-07-29

We present a model for a Yb-doped distributed Bragg reflector (DBR) waveguide laser fabricated in phosphate glass using the femtosecond laser direct-write technique. The model gives emphasis to transverse integrals to investigate the energy distribution in a homogenously doped glass, which is an important feature of femtosecond laser inscribed waveguide lasers (WGLs). The model was validated with experiments comparing a DBR WGL and a fiber laser, and then used to study the influence of distributed rare earth dopants on the performance of such lasers. Approximately 15% of the pump power was absorbed by the doped "cladding" in the femtosecond laser inscribed Yb doped WGL case with the length of 9.8 mm. Finally, we used the model to determine the parameters that optimize the laser output such as the waveguide length, output coupler reflectivity and refractive index contrast.

Geographic Variation Immediate and Delayed Breast Reconstruction Utilization in Ontario, Canada and Plastic Surgeon Availability: A Population-Based Observational Study.

PubMed

Platt, Jennica; Zhong, Toni; Moineddin, Rahim; Booth, Gillian L; Easson, Alexandra M; Fernandes, Kimberly; Gozdyra, Peter; Baxter, Nancy N

2015-08-01

Utilization of breast reconstruction (BR) is low in many jurisdictions. We studied the geographical and surgical workforce factors that contribute to access and use of BR using a small area analysis approach with a geographical unit of analysis. We linked administrative data from Ontario Canada to calculate the age-standardized rates for immediate BR (IBR) (same time as mastectomy) between 2002 and 2011, and delayed BR (DBR) (within 3 years of mastectomy) for each county. The influence of plastic surgeon access on variation in county rates of BR was examined using Poisson random effects models. 12,663 women underwent mastectomy in Ontario; 2,948 had BR within 3 years (23.3%). Over 50% of the counties had no access to any plastic surgeon. County IBR rates ranged from 0 to 21.5%; plastic surgeon access explained 46% of geographic variation (p<0.0001). IBR rates in counties with very low, low, and moderate access to plastic surgeons were significantly less than counties with high access (relative rate [RR] 0.48 [95% confidence interval (CI) 0.35-0.66], RR 0.61 [CI 0.43-0.87] and RR 0.70 [CI 0.52-0.96], respectively) after adjusting for age and county socioeconomic characteristics. For DBR, while there was less geographic variation, very low access counties demonstrated reduced rates (RR 0.60 [CI 0.47-0.76]). Geographic access to a plastic surgeon is a major determinant of BR. Targeted interventions for regions without high access to plastic surgeons may improve overall rates and reduce geographic disparities in care, particularly for IBR.

DBR and DFB Lasers in Neodymium- and Ytterbium-Doped Photothermorefractive Glasses

NASA Technical Reports Server (NTRS)

Ryasnyanskiy, Aleksandr; Vorobiev, N.; Smirnov, V.; Lumeau, J.; Glebov, A.; Mokhun, O..; Spiegelberg, Ch.; Krainak, Michael A.; Glebov, A.; Glebov, L.

2014-01-01

The first demonstration, to the best of our knowledge, of distributed Bragg reflector (DBR) and monolithic distributed feedback (DFB) lasers in photothermorefractive glass doped with rare-earth ions is reported. The lasers were produced by incorporation of the volume Bragg gratings into the laser gain elements. A monolithic single-frequency solid-state laser with a line width of 250 kHz and output power of 150 mW at 1066 nm is demonstrated.

A highly distributed Bragg stack with unique geometry provides effective camouflage for Loliginid squid eyes

PubMed Central

Holt, Amanda L.; Sweeney, Alison M.; Johnsen, Sönke; Morse, Daniel E.

2011-01-01

Cephalopods possess a sophisticated array of mechanisms to achieve camouflage in dynamic underwater environments. While active mechanisms such as chromatophore patterning and body posturing are well known, passive mechanisms such as manipulating light with highly evolved reflectors may also play an important role. To explore the contribution of passive mechanisms to cephalopod camouflage, we investigated the optical and biochemical properties of the silver layer covering the eye of the California fishery squid, Loligo opalescens. We discovered a novel nested-spindle geometry whose correlated structure effectively emulates a randomly distributed Bragg reflector (DBR), with a range of spatial frequencies resulting in broadband visible reflectance, making it a nearly ideal passive camouflage material for the depth at which these animals live. We used the transfer-matrix method of optical modelling to investigate specular reflection from the spindle structures, demonstrating that a DBR with widely distributed thickness variations of high refractive index elements is sufficient to yield broadband reflectance over visible wavelengths, and that unlike DBRs with one or a few spatial frequencies, this broadband reflectance occurs from a wide range of viewing angles. The spindle shape of the cells may facilitate self-assembly of a random DBR to achieve smooth spatial distributions in refractive indices. This design lends itself to technological imitation to achieve a DBR with wide range of smoothly varying layer thicknesses in a facile, inexpensive manner. PMID:21325315

Monolithic subwavelength high refractive-index-contrast grating VCSELs

NASA Astrophysics Data System (ADS)

Gebski, Marcin; Dems, Maciej; Lott, James A.; Czyszanowski, Tomasz

2016-03-01

In this paper we present optical design and simulation results of vertical-cavity surface-emitting lasers (VCSELs) that incorporate monolithic subwavelength high refractive-index-contrast grating (MHCG) mirrors - a new variety of HCG mirror that is composed of high index material surrounded only on one side by low index material. We show the impact of an MHCG mirror on the performance of 980 nm VCSELs designed for high bit rate and energy-efficient optical data communications. In our design, all or part of the all-semiconductor top coupling distributed Bragg reflector mirror is replaced by an undoped gallium-arsenide MHCG. We show how the optical field intensity distribution of the VCSEL's fundamental mode is controlled by the combination of the number of residual distributed Bragg reflector (DBR) mirror periods and the physical design of the topmost gallium-arsenide MHCG. Additionally, we numerically investigate the confinement factors of our VCSELs and show that this parameter for the MHCG DBR VCSELs may only be properly determined in two or three dimensions due to the periodic nature of the grating mirror.

Comparison for 1030nm DBR-tapered diode lasers with 10W central lobe output power and different grating layouts for wavelength stabilization and lateral spatial mode filtering

NASA Astrophysics Data System (ADS)

Müller, André; Zink, Christof; Fricke, Jörg; Bugge, Frank; Erbert, Götz; Sumpf, Bernd; Tränkle, Günther

2018-02-01

1030 nm DBR tapered diode lasers with different lateral layouts are presented. The layout comparison includes lasers with straight waveguide and grating, tapered waveguide and straight grating, and straight waveguide and tapered grating. The lasers provide narrowband emission and optical output powers up to 15 W. The highest diffraction-limited central lobe output power of 10.5 W is obtained for lasers with tapered gratings only. Small variations in central lobe output power with RW injection current density also indicate the robustness of that layout. For lasers with tapered waveguides, high RW injection current densities up to 150 A/mm2 have to be applied in order to obtain high central lobe output powers. Lasers with straight waveguide and grating operate best at low RW injection current densities, 50 A/mm2 applied in this study. Using the layout optimizations discussed in this study may help to increase the application potential of DBR tapered diode lasers.

Electroabsorption-modulated widely tunable DBR laser transmitter for WDM-PONs.

PubMed

Han, Liangshun; Liang, Song; Wang, Huitao; Qiao, Lijun; Xu, Junjie; Zhao, Lingjuan; Zhu, Hongliang; Wang, Baojun; Wang, Wei

2014-12-01

We present an InP based distributed Bragg reflector (DBR) laser transmitter which has a wide wavelength tuning range and a high chip output power for wavelength division multiplexing passive optical network (WDM-PON) applications. By butt-jointing InGaAsP with 1.45 µm emission wavelength as the material of the grating section, the laser wavelength can be tuned for over 13 nm by the DBR current. Accompanied by varying the chip temperature, the tuning range can be further enlarged to 16 nm. With the help of the integrated semiconductor optical amplifier (SOA), the largest chip output power is over 30 mW. The electroabsorption modulator (EAM) is integrated into the device by the selective-area growth (SAG) technique. The 3 dB small signal modulation bandwidth of the EAM is over 13 GHz. The device has both a simple tuning scheme and a simple fabrication procedure, making it suitable for low cost massive production which is desirable for WDM-PON uses.

Integrated photodiodes complement the VCSEL platform

NASA Astrophysics Data System (ADS)

Grabherr, Martin; Gerlach, Philipp; King, Roger; Jäger, Roland

2009-02-01

Many VCSEL based applications require optical feedback of the emitted light. E.g. light output monitor functions in transceivers are used to compensate for thermally induced power variation, power degradation, or even breakdown of pixels if logic for redundancy is available. In this case integrated photodiodes offer less complex assembly compared to widely used hybrid solutions, e.g. known in LC-TOSA assemblies. Especially for chip-on-board (COB) assembly and array configurations, integrated monitor diodes offer a simple and compact power monitoring possibility. For 850 nm VCSELs the integrated photodiodes can be placed between substrate and bottom-DBR, on top of the top-DBR, or inbetween the layer sequence of one DBR. Integrated intra-cavity photodiodes offer superior characteristics in terms of reduced sensitivity for spontaneously emitted light [1] and thus are very well suited for power monitoring or even endof- life (EOL) detection. We present an advanced device design for an intra-cavity photodiode and according performance data in comparison with competing approaches.

Fabrication of high reflectivity nanoporous distributed Bragg reflectors by controlled electrochemical etching of GaN

NASA Astrophysics Data System (ADS)

Lee, Seung-Min; Kang, Jin-Ho; Lee, June Key; Ryu, Sang-Wan

2016-09-01

The nanoporous medium is a valuable feature of optical devices because of its variable optical refractive index with porosity. One important application is in a GaN-based vertical cavity surface emitting laser having a distributed Bragg reflector (DBR) composed of alternating nanoporous and bulk GaNs. However, optimization of the fabrication process for high reflectivity DBRs having wellcontrolled high reflection bands has not been studied yet. We used electrochemical etching to study the fabrication process of a nanoporous GaN DBR and analyzed the relationship between the morphology and optical reflectivity. Several electrolytes were examined for the formation of the optimized nanoporous structure. A highly reflective DBRs having reflectivity of ~100% were obtained over a wide wavelength range of 450-750 nm. Porosification of semiconductors into nanoporous layers could provide a high reflectivity DBR due to controlled index-contrast, which would be advantages for the construction of a high-Q optical cavity.

Laser source for dimensional metrology: investigation of an iodine stabilized system based on narrow linewidth 633 nm DBR diode

NASA Astrophysics Data System (ADS)

Rerucha, Simon; Yacoot, Andrew; Pham, Tuan M.; Cizek, Martin; Hucl, Vaclav; Lazar, Josef; Cip, Ondrej

2017-04-01

We demonstrated that an iodine stabilized distributed Bragg reflector (DBR) diode based laser system lasing at a wavelength in close proximity to λ =633 nm could be used as an alternative laser source to the helium-neon lasers in both scientific and industrial metrology. This yields additional advantages besides the optical frequency stability and coherence: inherent traceability, wider optical frequency tuning range, higher output power and high frequency modulation capability. We experimentally investigated the characteristics of the laser source in two major steps: first using a wavelength meter referenced to a frequency comb controlled with a hydrogen maser and then on an interferometric optical bench testbed where we compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology, especially in conjunction with novel interferometric detection methods exploiting high frequency modulation or multiaxis measurement systems.

Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

2017-03-01

Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

Optical Characterizations of VCSEL for Emission at 850 nm with Al Oxide Confinement Layers

NASA Astrophysics Data System (ADS)

Mokhtari, Merwan; Pagnod-Rossiaux, Philippe; Laruelle, Francois; Landesman, Jean-Pierre; Moreac, Alain; Levallois, Christophe; Cassidy, Daniel T.

2018-03-01

In-plane micro-photoluminescence (μ-PL) and micro-reflectivity measurements have been performed at room temperature by optical excitation perpendicular to the surface of two different structures: a complete vertical surface-emitting laser (VCSEL) structure and a VCSEL without the upper p-type distributed Bragg reflector (P-DBR). The two structures were both laterally oxidized and measurements were made on the top of oxidized and unoxidized regions. We show that, since the photoluminescence (PL) spectra consist of the cumulative effect of InGaAs/AlGaAs multi-quantum wells (MQWs) luminescence and interferences in the DBR, the presence or not of the P-DBR and oxide layers can significantly modify the spectrum. μ-PL mapping performed on full VCSEL structures clearly shows oxidized and unoxidized regions that are not resolved with visible light optical microscopy. Finally, preliminary measurements of the degree of polarization (DOP) of the PL have been made on a complete VCSEL structure before and after an oxidation process. We obtain an image of DOP measured by polarization-resolved μ-PL. These measurements allow us to evaluate the main components of strain.

Nanoporous distributed Bragg reflectors on free-standing nonpolar m-plane GaN

NASA Astrophysics Data System (ADS)

Mishkat-Ul-Masabih, Saadat; Luk, Ting Shan; Rishinaramangalam, Ashwin; Monavarian, Morteza; Nami, Mohsen; Feezell, Daniel

2018-01-01

We report the fabrication of m-plane nanoporous distributed Bragg reflectors (DBRs) on free-standing GaN substrates. The DBRs consist of 15 pairs of alternating undoped and highly doped n-type ([Si] = ˜3.7 × 1019 cm-3) GaN. Electrochemical (EC) etching was performed to convert the highly doped regions into a porous material, consequently reducing the effective refractive index of the layers. We demonstrate a DBR with peak reflectance greater than 98% at 450 nm with a stopband width of ˜72 nm. The polarization ratio of an incident polarized light source remains identical after reflection from the DBR, verifying that there is no drop in the polarization ratio due to the interfaces between the porous layers. We also quantify the porosity under various EC bias conditions for layers with different doping concentrations. The bias voltage controls the average pore diameter, while the pore density is primarily determined by the doping concentration. The results show that nanoporous DBRs on nonpolar free-standing GaN are promising candidates for high-reflectance, lattice-matched DBR mirrors for GaN-based resonant cavity devices.

Study of phase-locked diode laser array and DFB/DBR surface emitting laser diode

NASA Astrophysics Data System (ADS)

Hsin, Wei

New types of phased-array and surface-emitting lasers are designed. The importance and approaches (or structures) of different phased array and surface emitting laser diodes are reviewed. The following are described: (1) a large optical cavity channel substrate planar laser array with layer thickness chirping; (2) a vertical cavity surface emitter with distributed feedback (DFB) optical cavity and a transverse junction buried heterostructure; (3) a microcavity distributed Bragg reflector (DBR) surface emitter; and (4) two surface emitting laser structures which utilized lateral current injection schemes to overcome the problems occurring in the vertical injection scheme.

Co-extruded mechanically tunable multilayer elastomer laser

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Mao, Guilin; Andrews, James; Singer, Kenneth; Baer, Eric; Hiltner, Anne; Song, Hyunmin; Shakya, Bijayandra

2011-04-01

We have fabricated and studied mechanically tunable elastomer dye lasers constructed in large area sheets by a single-step layer-multiplying co-extrusion process. The laser films consist of a central dye-doped (Rhodamine-6G) elastomer layer between two 128-layer distributed Bragg reflector (DBR) films comprised of alternating elastomer layers with different refractive indices. The central gain layer is formed by folding the coextruded DBR film to enclose a dye-doped skin layer. By mechanically stretching the elastomer laser film from 0% to 19%, a tunable miniature laser source was obtained with ˜50 nm continuous tunability from red to green.

MBE growth of vertical-cavity surface-emitting laser structure without real-time monitoring

NASA Astrophysics Data System (ADS)

Wu, C. Z.; Tsou, Y.; Tsai, C. M.

1999-05-01

Evaluation of producing a vertical-cavity surface-emitting laser (VCSEL) epitaxial structure by molecular beam epitaxy (MBE) without resorting to any real-time monitoring technique is reported. Continuous grading of Al xGa 1- xAs between x=0.12 to x=0.92 was simply achieved by changing the Al and Ga cell temperatures in no more than three steps per DBR period. Highly uniform DBR and VCSEL structures were demonstrated with a multi-wafer MBE system. Run-to-run standard deviation of reflectance spectrum center wavelength was 0.5% and 1.4% for VCSEL etalon wavelength.

1030-nm diode-laser-based light source delivering pulses with nanojoule energies and picosecond duration adjustable by mode locking or pulse gating operation

NASA Astrophysics Data System (ADS)

Klehr, A.; Liero, A.; Wenzel, H.; Bugge, F.; Brox, O.; Fricke, J.; Ressel, P.; Knigge, A.; Heinrich, W.; Tränkle, G.

2017-02-01

A new compact 1030 nm picosecond light source which can be switched between pulse gating and mode locking operation is presented. It consists of a multi-section distributed Bragg reflector (DBR) laser, an ultrafast multisection optical gate and a flared power amplifier (PA), mounted together with high frequency electronics and optical elements on a 5×4 cm micro bench. The master oscillator (MO) is a 10 mm long ridge wave-guide (RW) laser consisting of 200 μm long saturable absorber, 1500 μm long gain, 8000 μm long cavity, 200 μm long DBR and 100 μm long monitor sections. The 2 mm long optical gate consisting of several RW sections is monolithically integrated with the 4 mm long gain-guided tapered amplifier on a single chip. The light source can be switched between pulse gating and passive mode locking operation. For pulse gating all sections of the MO (except of the DBR and monitor sections) are forward biased and driven by a constant current. By injecting electrical pulses into one section of the optical gate the CW beam emitted by the MO is converted into a train of optical pulses with adjustable widths between 250 ps and 1000 ps. Peak powers of 20 W and spectral linewidths in the MHz range are achieved. Shorter pulses with widths between 4 ps and 15 ps and peak powers up to 50 W but larger spectral widths of about 300 pm are generated by mode locking where the saturable absorber section of the MO is reversed biased. The repetition rate of 4.2 GHz of the pulse train emitted by the MO can be reduced to values between 1 kHz and 100 MHz by utilizing the optical gate as pulse picker. The pulse-to-pulse distance can be controlled by an external trigger source.

Tuning of successively scanned two monolithic Vernier-tuned lasers and selective data sampling in optical comb swept source optical coherence tomography

PubMed Central

Choi, Dong-hak; Yoshimura, Reiko; Ohbayashi, Kohji

2013-01-01

Monolithic Vernier tuned super-structure grating distributed Bragg reflector (SSG-DBR) lasers are expected to become one of the most promising sources for swept source optical coherence tomography (SS-OCT) with a long coherence length, reduced sensitivity roll-off, and potential capability for a very fast A-scan rate. However, previous implementations of the lasers suffer from four main problems: 1) frequencies deviate from the targeted values when scanned, 2) large amounts of noise appear associated with abrupt changes in injection currents, 3) optically aliased noise appears due to a long coherence length, and 4) the narrow wavelength coverage of a single chip limits resolution. We have developed a method of dynamical frequency tuning, a method of selective data sampling to eliminate current switching noise, an interferometer to reduce aliased noise, and an excess-noise-free connection of two serially scanned lasers to enhance resolution to solve these problems. An optical frequency comb SS-OCT system was achieved with a sensitivity of 124 dB and a dynamic range of 55-72 dB that depended on the depth at an A-scan rate of 3.1 kHz with a resolution of 15 μm by discretely scanning two SSG-DBR lasers, i.e., L-band (1.560-1.599 μm) and UL-band (1.598-1.640 μm). A few OCT images with excellent image penetration depth were obtained. PMID:24409394

Trends in breast reconstruction: Implications for the National Health Insurance Service.

PubMed

Hong, Ki Yong; Son, Yoosung; Chang, Hak; Jin, Ung Sik

2018-05-01

Breast reconstruction has become more common as mastectomy has become more frequent. In Korea, the National Health Insurance Service (NHIS) began covering breast reconstruction in April 2015. This study aimed to investigate trends in mastectomy and breast reconstruction over the past 10 years and to evaluate the impact of NHIS coverage on breast reconstruction. Nationwide data regarding mastectomy and breast reconstruction were collected from the Korean Breast Cancer Society registry database. Multiple variables were analyzed in the records of patients who underwent breast reconstruction from January 2005 to March 2017 at a single institution. At Seoul National University Hospital, the total number of reconstruction cases increased 13-fold from 2005 to 2016. The proportion of immediate breast reconstruction (IBR) cases out of all cases of total mastectomy increased from 4% in 2005 to 52.0% in 2016. The proportion of delayed breast reconstruction (DBR) cases out of all cases of breast reconstruction and the overall number of DBR cases increased from 8.8% (20 cases) in 2012 to 18.3% (76 cases) in 2016. After NHIS coverage was initiated, the proportions of IBR and DBR showed statistically significant increases (P<0.05). Among the IBR cases, the percentage of prosthesis-based reconstructions increased significantly (P<0.05), but this trend was not found with DBR. Total mastectomy became significantly more common after the expansion of NHIS coverage (P<0.05). Over the last decade, there has been an increase in mastectomy and breast reconstruction, and the pace of increase accelerated after the expansion of NHIS coverage. It is expected that breast reconstruction will be a routine option for patients with breast cancer under the NHIS.

High-quality quantum-dot-based full-color display technology by pulsed spray method

NASA Astrophysics Data System (ADS)

Chen, Kuo-Ju; Chen, Hsin-Chu; Tsai, Kai-An; Lin, Chien-Chung; Tsai, Hsin-Han; Chien, Shih-Hsuan; Cheng, Bo-Siao; Hsu, Yung-Jung; Shih, Min-Hsiung; Kuo, Hao-Chung

2013-03-01

We fabricated the colloidal quantum-dot light-emitting diodes (QDLEDs) with the HfO2/SiO2-distributed Bragg reflector (DBR) structure using a pulsed spray coating method. Moreover, pixelated RGB arrays, 2-in. wafer-scale white light emission, and an integrated small footprint white light device were demonstrated. The experimental results showed that the intensity of red, blue, and green (RGB) emissions exhibited considerable enhancement because of the high reflectivity in the UV region by the DBR structure, which subsequently increased the use in the UV optical pumping of RGB QDs. In this experiment, a pulsed spray coating method was crucial in providing uniform RGB layers, and the polydimethylsiloxane (PDMS) film was used as the interface layer between each RGB color to avoid crosscontamination and self-assembly of QDs. Furthermore, the chromaticity coordinates of QDLEDs with the DBR structure remained constant under various pumping powers in the large area sample, whereas a larger shift toward high color temperatures was observed in the integrated device. The resulting color gamut of the proposed QDLEDs covered an area 1.2 times larger than that of the NTSC standard, which is favorable for the next generation of high-quality display technology.

100-mW high-power three-section tunable distributed Bragg reflector laser diodes with a real refractive-index-guided self-aligned structure

NASA Astrophysics Data System (ADS)

Takayama, Toru; Mochida, Atsunori; Orita, Kenji; Tamura, Satoshi; Ohnishi, Toshikazu; Yuri, Masaaki; Shimizu, Hirokazu

2002-05-01

High-power (>100mW) 820 nm-band distributed Bragg reflector (DBR) laser diodes (LDs) with stable fundamental transverse mode operation and continuous wavelength tuning characteristics have been developed. To obtain high-power LDs with a stable fundamental transverse mode in 820 nm wavelength range, an AlGaAs narrow stripe (2.0 micrometers ) real refractive-index-guided self-aligned (RISA) structure is utilized. In the RISA structure, the index step between inside and outside the stripe region ((Delta) n) can be precisely controlled in the order of 10-3). To maintain a stable fundamental transverse mode up to an output power over 100 mW, (Delta) n is designed to be 4x10-3. Higher-order transverse modes are effectively suppressed by a narrow stripe geometry. Further, to achieve continuous wavelength tuning capability, the three-section LD structure, which consists of the active (700micrometers ), phase control (300micrometers ), and DBR(500micrometers ) sections, is incorporated. Our DBR LDs show a maximum output power over 200mW with a stable fundamental transverse mode, and wavelength tuning characteristics ((Delta) (lambda) ~2nm) under 100 mW CW operation.

A low-threshold high-index-contrast grating (HCG)-based organic VCSEL

NASA Astrophysics Data System (ADS)

Shayesteh, Mohammad Reza; Darvish, Ghafar; Ahmadi, Vahid

2015-12-01

We propose a low-threshold high-index-contrast grating (HCG)-based organic vertical-cavity surface-emitting laser (OVCSEL). The device has the feasibility to apply both electrical and optical excitation. The microcavity of the laser is a hybrid photonic crystal (HPC) in which the top distributed Bragg reflector (DBR) is replaced by a sub-wavelength high-contrast-grating layer, and provides a high-quality factor. The simulated quality factor of the microcavity is shown to be as high as 282,000. We also investigate the threshold behavior and the dynamics of the OVCSEL optically pumped with sub-picosecond pulses. Results from numerical simulation show that lasing threshold is 75 nJ/cm2.

Giant enhancement of second harmonic generation in nonlinear photonic crystals with distributed Bragg reflector mirrors.

PubMed

Ren, Ming-Liang; Li, Zhi-Yuan

2009-08-17

We theoretically investigate second harmonic generation (SHG) in one-dimensional multilayer nonlinear photonic crystal (NPC) structures with distributed Bragg reflector (DBR) as mirrors. The NPC structures have periodic modulation on both the linear and second-order susceptibility. Three major physical mechanisms, quasi-phase matching (QPM) effect, slow light effect at photonic band gap edges, and cavity effect induced by DBR mirrors can be harnessed to enhance SHG. Selection of appropriate structural parameters can facilitate coexistence of these mechanisms to act collectively and constructively to create very high SHG conversion efficiency with an enhancement by up to seven orders of magnitude compared with the ordinary NPC where only QPM works. (c) 2009 Optical Society of America

Vertical-Cavity Surface-Emitting Lasers: Design, Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Geels, Randall Scott

The theory, design, fabrication, and testing of vertical-cavity surface-emitting lasers (VCSELs) is explored in depth. The design of the distributed Bragg reflector (DBR) mirrors is thoroughly treated and both analytic and numerical approaches for computing the reflectivity are covered. The electrical properties of the DBR mirrors are also considered and graded interfaces are found to be critical in reducing the series voltage drop in the mirrors. Thickness variations due to growth rate uncertainties are considered and the permissible thickness inaccuracies are discussed. Layer thickness variations of several percent can be tolerated without large changes in the threshold current. The growth of VCSELs by molecular beam epitaxy (MBE) is described in detail as is the device processing technology for broad area as well as small area devices. Results from numerous devices are reported. Broad area in-plane lasers were used to characterize the material and determine the internal parameters. Broad area VCSELs were fabricated to determine the characteristics of the VCSEL cavity. Small area VCSELs were fabricated and extensively tested. Measured and derived parameters from small area devices include: threshold current (~0.7 mA), peak output power (>3 mW), maximum operation temperature (>110^ circC), output power at 100^ circC (~0.4 mW), and linewidth (85 MHz). The near field, far field, and polarization characteristics were also measured.

[Cartography and geographical spread of the adventitious species of brome (Bromus spp.) among cereals in the Sais area of Morocco].

PubMed

Hamal, A; Benbella, M; Rzozi, S B; Bouhache, M; Msatef, Y

2001-01-01

Bromus spp is causing serious problems in wheat in the Sais area. However, the damage of this weed varies from one region to another according to the agro-climatic conditions and crop systems. The characterization of the infestation level in each situation is a prerequisite to develop a control strategy adapted to each environment. This study was undertaken in order to determine the infestation level and geographical spread of the weedy brome (Bromus spp) on wheat in Sais following crop systems and pedo-climatic conditions. The results obtained during two consecutive years (1998-99 and 1999-2000) revealed that ripgut brome (Bromus rigidus Roth.) was the most dominant species in wheat fields in the surveyed regions, followed by B. rubens L., B. sterilis L., B. madritensis L. and B. mollus L. Among, 18 regions and 100 infested wheat fields, 16.67% of fields were slightly infested (Plant density of Bromus (Dbr < 90 plants/m2, 61.11% were moderately infested (90 < Dbr < 290 plants/m2) and 22.22% were highly infested (Dbr > 400 plants/m2). The maximum relative frequency was obtained with Bromus rigidus (47.15%) and the coverage was 40.43%. But, for B.rubens, B. madritensis and B. sterilis, the relative frequencies were respectively 31.42; 26 and 15% and their coverages were respectively 28.9, 20.4 and 12.5%.

Light-Output Enhancement of GaN-Based Light-Emitting Diodes with Three-Dimensional Backside Reflectors Patterned by Microscale Cone Array

PubMed Central

Hu, Jinyong; Wang, Hong

2014-01-01

Three-dimensional (3D) backside reflector, compared with flat reflectors, can improve the probability of finding the escape cone for reflecting lights and thus enhance the light-extraction efficiency (LEE) for GaN-based light-emitting diode (LED) chips. A triangle-lattice of microscale SiO2 cone array followed by a 16-pair Ti3O5/SiO2 distributed Bragg reflector (16-DBR) was proposed to be attached on the backside of sapphire substrate, and the light-output enhancement was demonstrated by numerical simulation and experiments. The LED chips with flat reflectors or 3D reflectors were simulated using Monte Carlo ray tracing method. It is shown that the LEE increases as the reflectivity of backside reflector increases, and the light-output can be significantly improved by 3D reflectors compared to flat counterparts. It can also be observed that the LEE decreases as the refractive index of the cone material increases. The 3D 16-DBR patterned by microscale SiO2 cone array benefits large enhancement of LEE. This microscale pattern was prepared by standard photolithography and wet-etching technique. Measurement results show that the 3D 16-DBR can provide 12.1% enhancement of wall-plug efficiency, which is consistent with the simulated value of 11.73% for the enhancement of LEE. PMID:25133262

An evolution-based DNA-binding residue predictor using a dynamic query-driven learning scheme.

PubMed

Chai, H; Zhang, J; Yang, G; Ma, Z

2016-11-15

DNA-binding proteins play a pivotal role in various biological activities. Identification of DNA-binding residues (DBRs) is of great importance for understanding the mechanism of gene regulations and chromatin remodeling. Most traditional computational methods usually construct their predictors on static non-redundant datasets. They excluded many homologous DNA-binding proteins so as to guarantee the generalization capability of their models. However, those ignored samples may potentially provide useful clues when studying protein-DNA interactions, which have not obtained enough attention. In view of this, we propose a novel method, namely DQPred-DBR, to fill the gap of DBR predictions. First, a large-scale extensible sample pool was compiled. Second, evolution-based features in the form of a relative position specific score matrix and covariant evolutionary conservation descriptors were used to encode the feature space. Third, a dynamic query-driven learning scheme was designed to make more use of proteins with known structure and functions. In comparison with a traditional static model, the introduction of dynamic models could obviously improve the prediction performance. Experimental results from the benchmark and independent datasets proved that our DQPred-DBR had promising generalization capability. It was capable of producing decent predictions and outperforms many state-of-the-art methods. For the convenience of academic use, our proposed method was also implemented as a web server at .

Monolithic narrow-linewidth InGaAsP semiconductor laser for coherent optical communications

NASA Technical Reports Server (NTRS)

Palfrey, S. L.; Enstrom, R. E.; Longeway, P. A.

1989-01-01

A design for a monolithic narrow-linewidth InGaAsP diode laser has been developed using a multiple-quantum-well (MQW) extended-passive-cavity distributed-Bragg-reflector (DBR) laser design. Theoretical results indicate that this structure has the potential for a linewidth of 100 kHz or less. To realize this device, a number of the fabrication techniques required to integrate low-loss passive waveguides with active regions have been developed using a DBR laser structure. In addition, the MOCVD growth of InGaAs MQW laser structures has been developed, and threshold current densities as low as 1.6 kA/sq cm have been obtained from broad-stripe InGaAs/InGaAsP separate-confinement-heterostructure MQW lasers.

Telecom wavelength single quantum dots with very small excitonic fine-structure splitting

NASA Astrophysics Data System (ADS)

Kors, Andrei; Reithmaier, Johann Peter; Benyoucef, Mohamed

2018-04-01

We report on molecular beam epitaxy growth of symmetric InAs/InP quantum dots (QDs) emitting at a telecom C-band (1.55 μm) with an ultra-small excitonic fine-structure splitting of ˜2 μeV. The QDs are grown on a distributed Bragg reflector (DBR) and systematically characterized by micro-photoluminescence (μ-PL) measurements. One order of magnitude of QD PL intensity enhancement is observed in comparison to the samples without DBR. A combination of power-dependent and polarization-resolved measurements reveals background-free exciton, biexciton, and dark exciton emission with a resolution-limited linewidth below 35 μeV and a biexciton binding energy of ˜1 meV. The results are confirmed by statistical measurements of about 20 QDs.

Distributed Bragg reflector tapered diode lasers emitting more than 10 W at 1154 nm

NASA Astrophysics Data System (ADS)

Feise, D.; Bugge, F.; Matalla, M.; Thies, A.; Ressel, P.; Blume, G.; Hofmann, J.; Paschke, K.

2018-02-01

Distributed Bragg reflector tapered diode lasers (DBR-TPL) emitting at 1154 nm are ideal light sources to be implemented into medical devices and hand-held tools for treatment in dermatology and ophthalmology at 577 nm due to their high spectral radiance enabling second harmonic generation from near infrared to yellow. In this work, we present DBR-TPLs which are able to emit more than 10 W in continuous-wave operation with a narrow spectral emission at 1154 nm and a very good beam quality providing excellent spectral radiance. The investigated DBRTPLs are based on three different epitaxial structures with varying vertical far field angles of 35°, 26°, and 17°. To optimize the coupling efficiency into non-linear crystals we studied DBR-TPL with a vertical far field angle of approx. 17° based on an asymmetrical super large optical cavity epitaxial structure. At a pump current of 18 A these devices are able to emit more than 9 W at 25°C and nearly 11 W at 10°C. The spectral emission is very narrow (ΔλFWHM = 18 pm) and single mode over the entire current range. While the beam quality factor M2 according to the 1/e2-level remains 1.1, the M2 according to second order moments deteriorates when the laser is pumped with higher currents. Therefore, the power content in the central lobe increases somewhat less rapidly than the total power.

Using diagrams versus text for spaced restudy: Effects on learning in 10th grade biology classes.

PubMed

Bergey, Bradley W; Cromley, Jennifer G; Kirchgessner, Mandy L; Newcombe, Nora S

2015-03-01

Spaced restudy has been typically tested with written learning materials, but restudy with visual representations in actual classrooms is under-researched. We compared the effects of two spaced restudy interventions: A Diagram-Based Restudy (DBR) warm-up condition and a business-as-usual Text-Based Restudy (TBR) warm-up condition. One hundred and twenty-eight consented high school students in 15 classes. Students completed daily warm-ups over a 4-week period. Students were randomly assigned to conditions within classrooms. Warm-ups were independently completed at the start of class meetings and consisted of questions about content covered 1-10 days prior to each warm-up. Students received feedback on their answers each week. A series of ANOVAs and ANCOVAs was conducted. Results showed equal and significant growth from pre- to post-test for both conditions (d = .31-.67) on three outcomes: Biology knowledge, biology diagram comprehension (near transfer), and geology diagram comprehension (far transfer). ANCOVA results suggested that the magnitude of this increase was linked to the number of questions attempted during the intervention. For the DBR condition only, there were interactions with content knowledge on diagram comprehension gain scores and interactions with spatial scores on biology knowledge gain scores. Students with lower biology knowledge and lower Paper Folding Test scores were disadvantaged in the DBR condition, whereas the TBR condition was equitable across all levels of knowledge and spatial ability. © 2014 The British Psychological Society.

GaN-based flip-chip LEDs with highly reflective ITO/DBR p-type and via hole-based n-type contacts for enhanced current spreading and light extraction

NASA Astrophysics Data System (ADS)

Zhou, Shengjun; Zheng, Chenju; Lv, Jiajiang; Gao, Yilin; Wang, Ruiqing; Liu, Sheng

2017-07-01

We demonstrate GaN-based double-layer electrode flip-chip light-emitting diodes (DLE-FCLED) with highly reflective indium-tin oxide (ITO)/distributed bragg reflector (DBR) p-type contact and via hole-based n-type contacts. Transparent thin ITO in combination with TiO2/SiO2 DBR is used for reflective p-type ohmic contact, resulting in a significant reduction in absorption of light by opaque metal electrodes. The finely distributed via hole-based n-type contacts are formed on the n-GaN layer by etching via holes through p-GaN and multiple quantum well (MQW) active layer, leading to reduced lateral current spreading length, and hence alleviated current crowding effect. The forward voltage of the DLE-FCLED is 0.31 V lower than that of the top-emitting LED at 90 mA. The light output power of DLE-FCLED is 15.7% and 80.8% higher than that of top-emitting LED at 90 mA and 300 mA, respectively. Compared to top- emitting LED, the external quantum efficiency (EQE) of DLE-FCLED is enhanced by 15.4% and 132% at 90 mA and 300 mA, respectively. The maximum light output power of the DLE-FCLED obtained at 195.6 A/cm2 is 1.33 times larger than that of the top-emitting LED obtained at 93 A/cm2.

Light trapping in thin film solar cells using textured photonic crystal

DOEpatents

Yi, Yasha [Somerville, MA; Kimerling, Lionel C [Concord, MA; Duan, Xiaoman [Amesbury, MA; Zeng, Lirong [Cambridge, MA

2009-01-27

A solar cell includes a photoactive region that receives light. A photonic crystal is coupled to the photoactive region, wherein the photonic crystal comprises a distributed Bragg reflector (DBR) for trapping the light.

16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

PubMed

Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

2011-01-17

Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future.

Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures

DOE PAGES

Horie, Yu; Arbabi, Amir; Arbabi, Ehsan; ...

2016-05-19

Here, we propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-Perot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250nm around λ = 1550nm (Δλ/λ = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwichedmore » metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling.« less

Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses.

PubMed

Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

2011-06-20

For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.

High-Quality Crystal Growth and Characteristics of AlGaN-Based Solar-Blind Distributed Bragg Reflectors with a Tri-layer Period Structure

PubMed Central

Chang, Jianjun; Chen, Dunjun; Yang, Lianhong; Liu, Yanli; Dong, Kexiu; Lu, Hai; Zhang, Rong; Zheng, Youdou

2016-01-01

To realize AlGaN-based solar-blind ultraviolet distributed Bragg reflectors (DBRs), a novel tri-layer AlGaN/AlInN/AlInGaN periodical structure that differs from the traditional periodically alternating layers of high- and low-refractive-index materials was proposed and grown on an Al0.5Ga0.5N template via metal-organic chemical vapour deposition. Because of the intentional design of the AlInGaN strain transition layer, a state-of-the-art DBR structure with atomic-level-flatness interfaces was achieved using an AlGaN template. The fabricated DBR exhibits a peak reflectivity of 86% at the centre wavelength of 274 nm and a stopband with a full-width at half-maximum of 16 nm. PMID:27381651

DOW-PR DOlphin and Whale Pods Routing Protocol for Underwater Wireless Sensor Networks (UWSNs).

PubMed

Wadud, Zahid; Ullah, Khadem; Hussain, Sajjad; Yang, Xiaodong; Qazi, Abdul Baseer

2018-05-12

Underwater Wireless Sensor Networks (UWSNs) have intrinsic challenges that include long propagation delays, high mobility of sensor nodes due to water currents, Doppler spread, delay variance, multipath, attenuation and geometric spreading. The existing Weighting Depth and Forwarding Area Division Depth Based Routing (WDFAD-DBR) protocol considers the weighting depth of the two hops in order to select the next Potential Forwarding Node (PFN). To improve the performance of WDFAD-DBR, we propose DOlphin and Whale Pod Routing protocol (DOW-PR). In this scheme, we divide the transmission range into a number of transmission power levels and at the same time select the next PFNs from forwarding and suppressed zones. In contrast to WDFAD-DBR, our scheme not only considers the packet upward advancement, but also takes into account the number of suppressed nodes and number of PFNs at the first and second hops. Consequently, reasonable energy reduction is observed while receiving and transmitting packets. Moreover, our scheme also considers the hops count of the PFNs from the sink. In the absence of PFNs, the proposed scheme will select the node from the suppressed region for broadcasting and thus ensures minimum loss of data. Besides this, we also propose another routing scheme (whale pod) in which multiple sinks are placed at water surface, but one sink is embedded inside the water and is physically connected with the surface sink through high bandwidth connection. Simulation results show that the proposed scheme has high Packet Delivery Ratio (PDR), low energy tax, reduced Accumulated Propagation Distance (APD) and increased the network lifetime.

DOW-PR DOlphin and Whale Pods Routing Protocol for Underwater Wireless Sensor Networks (UWSNs)

PubMed Central

Wadud, Zahid; Ullah, Khadem; Hussain, Sajjad; Yang, Xiaodong; Qazi, Abdul Baseer

2018-01-01

Underwater Wireless Sensor Networks (UWSNs) have intrinsic challenges that include long propagation delays, high mobility of sensor nodes due to water currents, Doppler spread, delay variance, multipath, attenuation and geometric spreading. The existing Weighting Depth and Forwarding Area Division Depth Based Routing (WDFAD-DBR) protocol considers the weighting depth of the two hops in order to select the next Potential Forwarding Node (PFN). To improve the performance of WDFAD-DBR, we propose DOlphin and Whale Pod Routing protocol (DOW-PR). In this scheme, we divide the transmission range into a number of transmission power levels and at the same time select the next PFNs from forwarding and suppressed zones. In contrast to WDFAD-DBR, our scheme not only considers the packet upward advancement, but also takes into account the number of suppressed nodes and number of PFNs at the first and second hops. Consequently, reasonable energy reduction is observed while receiving and transmitting packets. Moreover, our scheme also considers the hops count of the PFNs from the sink. In the absence of PFNs, the proposed scheme will select the node from the suppressed region for broadcasting and thus ensures minimum loss of data. Besides this, we also propose another routing scheme (whale pod) in which multiple sinks are placed at water surface, but one sink is embedded inside the water and is physically connected with the surface sink through high bandwidth connection. Simulation results show that the proposed scheme has high Packet Delivery Ratio (PDR), low energy tax, reduced Accumulated Propagation Distance (APD) and increased the network lifetime. PMID:29757208

Dowel bar retrofit performance in Wisconsin.

DOT National Transportation Integrated Search

2010-05-01

In 1999, WisDOT constructed test sections on I-39 to evaluate the dowel bar retrofit (DBR) rehabilitation technique for faulted concrete pavement slabs. Two years later, mortar deterioration and debonding were noted in the dowel slots. In response to...

Dowel Bar Retrofit Mix Design and Specification : Technical Report

DOT National Transportation Integrated Search

2012-01-01

Current INDOT specifications for repair materials to be used in dowel bar retrofit (DBR) applications (Sections 507.08 and 901.07 of INDOTs Book of Specifications) are based, in large part, on the requirements of ASTM C 928 and the manufacturer-pr...

Integrated Duo Wavelength VCSEL Using an Electrically Pumped GaInAs/AlGaAs 980 nm Cavity at the Bottom and an Optically Pumped GaInAs/AlGaInAs 1550 nm Cavity on the Top

PubMed Central

Islam, Samiha Ishrat; Islam, Arnob; Islam, Saiful

2014-01-01

In this work, an integrated single chip dual cavity VCSEL has been designed which comprises an electrically pumped 980 nm bottom VCSEL section fabricated using GaInAs/AlGaAs MQW active region and a 1550 nm top VCSEL section constructed using GaInAs/AlGaInAs MQW active region but optically pumped using half of the produced 980 nm light entering into it from the electrically pumped bottom cavity. In this design, the active region of the intracavity structure 980 nm VCSEL consists of 3 quantum wells (QWs) using Ga0.847In0.153As, 2 barriers using Al0.03Ga0.97As, and 2 separate confinement heterostructures (SCH) using the same material as the barrier. The active region of the top emitting 1550 nm VCSEL consists of 3 QWs using Ga0.47In0.52As, 2 barriers using Al0.3Ga0.17In0.53As, and 2 SCHs using the same material as the barrier. The top DBR and the bottom DBR mirror systems of the 1550 nm VCSEL section plus the top and bottom DBR mirror systems of the 980 nm VCSEL section have been formed using GaAs/Al0.8Ga0.2As. Computations show that the VCSEL is capable of producing 8.5 mW of power at 980 nm from the bottom side and 2 mW of power at the 1550 nm from top side. PMID:27379335

Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

NASA Astrophysics Data System (ADS)

Bernhardi, E. H.; de Ridder, R. M.; Wörhoff, K.; Pollnau, M.

2013-03-01

We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a -3-dB width of 9 kHz and a long-term frequency stability of +/- 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 μm and 20 μm, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

Miniaturized imaging spectrometer based on Fabry-Perot MOEMS filters and HgCdTe infrared focal plane arrays

NASA Astrophysics Data System (ADS)

Velicu, S.; Buurma, C.; Bergeson, J. D.; Kim, Tae Sung; Kubby, J.; Gupta, N.

2014-05-01

Imaging spectrometry can be utilized in the midwave infrared (MWIR) and long wave infrared (LWIR) bands to detect, identify and map complex chemical agents based on their rotational and vibrational emission spectra. Hyperspectral datasets are typically obtained using grating or Fourier transform spectrometers to separate the incoming light into spectral bands. At present, these spectrometers are large, cumbersome, slow and expensive, and their resolution is limited by bulky mechanical components such as mirrors and gratings. As such, low-cost, miniaturized imaging spectrometers are of great interest. Microfabrication of micro-electro-mechanicalsystems (MEMS)-based components opens the door for producing low-cost, reliable optical systems. We present here our work on developing a miniaturized IR imaging spectrometer by coupling a mercury cadmium telluride (HgCdTe)-based infrared focal plane array (FPA) with a MEMS-based Fabry-Perot filter (FPF). The two membranes are fabricated from silicon-oninsulator (SOI) wafers using bulk micromachining technology. The fixed membrane is a standard silicon membrane, fabricated using back etching processes. The movable membrane is implemented as an X-beam structure to improve mechanical stability. The geometries of the distributed Bragg reflector (DBR)-based tunable FPFs are modeled to achieve the desired spectral resolution and wavelength range. Additionally, acceptable fabrication tolerances are determined by modeling the spectral performance of the FPFs as a function of DBR surface roughness and membrane curvature. These fabrication non-idealities are then mitigated by developing an optimized DBR process flow yielding high-performance FPF cavities. Zinc Sulfide (ZnS) and Germanium (Ge) are chosen as the low and the high index materials, respectively, and are deposited using an electron beam process. Simulations are presented showing the impact of these changes and non-idealities in both a device and systems level.

Electrically conductive ZnO/GaN distributed Bragg reflectors grown by hybrid plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Hjort, Filip; Hashemi, Ehsan; Adolph, David; Ive, Tommy; Haglund, Àsa

2017-02-01

III-nitride-based vertical-cavity surface-emitting lasers have so far used intracavity contacting schemes since electrically conductive distributed Bragg reflectors (DBRs) have been difficult to achieve. A promising material combination for conductive DBRs is ZnO/GaN due to the small conduction band offset and ease of n-type doping. In addition, this combination offers a small lattice mismatch and high refractive index contrast, which could yield a mirror with a broad stopband and a high peak reflectivity using less than 20 DBR-pairs. A crack-free ZnO/GaN DBR was grown by hybrid plasma-assisted molecular beam epitaxy. The ZnO layers were approximately 20 nm thick and had an electron concentration of 1×1019 cm-3, while the GaN layers were 80-110 nm thick with an electron concentration of 1.8×1018 cm-3. In order to measure the resistance, mesa structures were formed by dry etching through the top 3 DBR-pairs and depositing non-annealed Al contacts on the GaN-layers at the top and next to the mesas. The measured specific series resistance was dominated by the lateral and contact contributions and gave an upper limit of 10-3Ωcm2 for the vertical resistance. Simulations show that the ZnO electron concentration and the cancellation of piezoelectric and spontaneous polarization in strained ZnO have a large impact on the vertical resistance and that it could be orders of magnitudes lower than what was measured. This is the first report on electrically conductive ZnO/GaN DBRs and the upper limit of the resistance reported here is close to the lowest values reported for III-nitride-based DBRs.

Temperature-insensitive vertical-cavity surface-emitting lasers and method for fabrication thereof

DOEpatents

Chow, W.W.; Choquette, K.D.; Gourley, P.L.

1998-01-27

A temperature-insensitive vertical-cavity surface-emitting laser (VCSEL) and method for fabrication thereof are disclosed. The temperature-insensitive VCSEL comprises a quantum-well active region within a resonant cavity, the active region having a gain spectrum with a high-order subband (n {>=} 2) contribution thereto for broadening and flattening the gain spectrum, thereby substantially reducing any variation in operating characteristics of the VCSEL over a temperature range of interest. The method for forming the temperature-insensitive VCSEL comprises the steps of providing a substrate and forming a plurality of layers thereon for providing first and second distributed Bragg reflector (DBR) mirror stacks with an active region sandwiched therebetween, the active region including at least one quantum-well layer providing a gain spectrum having a high-order subband (n {>=} 2) gain contribution, and the DBR mirror stacks having predetermined layer compositions and thicknesses for providing a cavity resonance within a predetermined wavelength range substantially overlapping the gain spectrum. 12 figs.

Temperature-insensitive vertical-cavity surface-emitting lasers and method for fabrication thereof

DOEpatents

Chow, Weng W.; Choquette, Kent D.; Gourley, Paul L.

1998-01-01

A temperature-insensitive vertical-cavity surface-emitting laser (VCSEL) and method for fabrication thereof. The temperature-insensitive VCSEL comprises a quantum-well active region within a resonant cavity, the active region having a gain spectrum with a high-order subband (n.gtoreq.2) contribution thereto for broadening and flattening the gain spectrum, thereby substantially reducing any variation in operating characteristics of the VCSEL over a temperature range of interest. The method for forming the temperature-insensitive VCSEL comprises the steps of providing a substrate and forming a plurality of layers thereon for providing first and second distributed Bragg reflector (DBR) mirror stacks with an active region sandwiched therebetween, the active region including at least one quantum-well layer providing a gain spectrum having a high-order subband (n.gtoreq.2) gain contribution, and the DBR mirror stacks having predetermined layer compositions and thicknesses for providing a cavity resonance within a predetermined wavelength range substantially overlapping the gain spectrum.

Spectroscopic investigations on the orientation of 1,4-dibromonaphthalene on silver nanoparticles.

PubMed

Geetha, K; Umadevi, M; Sathe, G V; Erenler, R

2013-12-01

Silver nanoparticles (Ag NPs) have been prepared by solution combustion method with glycine as fuel. Silver nanoparticles were characterized by X-Ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and UV-visible spectroscopy. The prepared silver nanoparticles exhibit cubic crystalline structure with grain size of 59 nm. HRTEM image shows that the silver nanoparticles have strain and four-fold symmetry formed by twinning in the crystal structure. The optical adsorption spectrum shows that the surface plasmon resonance peak of silver is observed at 380 nm. The orientation of 1,4-dibromonaphthlaene (1,4-DBrN) on silver nanoparticles has been inferred from nRs and SERS spectral features. The absence of a C-H stretching vibrations, the observed high intense C-H out-of-plane bending modes and high intense C-Br stretching vibration suggest that the 1,4-DBrN molecule may be adsorbed in a 'stand-on' orientation to the surface. Copyright © 2013 Elsevier B.V. All rights reserved.

A Study of a Social Annotation Modeling Learning System

ERIC Educational Resources Information Center

Samuel, Roy David; Kim, Chanmin; Johnson, Tristan E.

2011-01-01

The transition from classroom instruction to e-learning raises pedagogical challenges for university instructors. A controlled integration of e-learning tools into classroom instruction may offer learners tangible benefits and improved effectiveness. This design-based research (DBR) study engaged students in e-learning activities integrated into…

Design Based Research Methodology for Teaching with Technology in English

ERIC Educational Resources Information Center

Jetnikoff, Anita

2015-01-01

Design based research (DBR) is an appropriate method for small scale educational research projects involving collaboration between teachers, students and researchers. It is particularly useful in collaborative projects where an intervention is implemented and evaluated in a grounded context. The intervention can be technological, or a new program…

Migrant Adult Learners and Digital Literacy: Using DBR to Support Teaching and Learning

ERIC Educational Resources Information Center

Vanek, Jenifer B.

2017-01-01

This research explores the difficulties faced by many migrant, refugee, and immigrant adults confronted with technological ubiquity in economically developed countries. Preparing migrant adult learners for the digital world by building digital literacy skills can help to maintain home language proficiency, support English language learning, and…

Effects of climate change on plant population growth rate and community composition change.

PubMed

Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

2015-01-01

The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

THE DEUTERIUM ISOTOPE RATE EFFECT IN FREE RADICAL REACTIONS OF t-CARBON DEUTERATED DDT AND ITS ANALOGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dachauer, A.C.

1962-01-01

DDT and several of its analogs were synthesized with deuterium in the t- carbon position so that any chemical reaction involving this site in the molecule would then be subject to the deuterium isotope rate effect. Lithium aluminum deuteride, used as the source of the deuterium, was employed to reduce trichloromethyl p-chlorophenyl ketone, trichloromethyl p-bromophenyl ketone, and trichloromethyl p-methoxyphenyl ketone to the corresponding alcohols. The alcohols were then condensed with chlorobenzene, bromobenzene, and anisole respectively to form 1,1,1-trichloro2,2-bis(p-chloro-phenyl)ethane-2-d (d-DDT), 1,1,1-trichloro-2,2-bis (p-bromophenyl)ethane-2-d (d-DBrDT), and 1,1, 1-trichloro- 2,2-bis (p-methoxyphenyl)ethane (d-methoxychlor). The deuterated and non- deuterated insecticides were identical in physical appearance andmore » melting points. Infrared spectra showed sigrificant differences; in particular, each deuterated compound had a distinctive band at ca 10.5 mu , missing in the spectra of the non-deuterated insecticides. NMR analysis confirmed the tertiary position of the deuterium and gave proof of high isotopic purity, each insecticide being 98% deuterated in the desired site. The isotope rate effect was first studied in the reaction of DDT, methoxychlor, and their deuterated analogs with alcoholic sodium- hydroxide. The base catalyzed dehydrohalogenation showed an isotope rate effect, k/sub H//k/sub D/, of the order of 5.4 for DDT and 8 for methoxychlor. The results were considered to be of a magnitude sufficient for the isotope rate effect to be manifested in the in vivo studies. The insecticides and their deuterated analogs were tested for toxicity on houseflies. The results showed that d-DDT and d-DBrDT were more toxic than their non-deuterated counterparts by a factor of ca 1.5 while d-methoxychlor showed a toxicity equal to methoxychlor. The results are explained on the basis of the detoxication process in the insects. In vitro studies showed that DDT-dehydrochlorinase, an enzyme capable of detoxifying DDT, manifested the isotope rate effect. It appeared, therefore, that in the detoxication process, the deuterated insecticide reacted more slowly, and though the initial dose given to the insect was less than that of the non- deuterated insecticide, the amount reaching the susceptible site in the insect was the same. The data support the view that at least one mode of resistance to DDT is chemical in nature and that the tertiary carbon-hydrogen group is involved. The data also indicated that susceptible houseflies contain some mechanlsm that can detoxify DDT and that this detoxication is chemical and subject to the isotope rate effect. (P.C.H.)« less

Monolithic all-fiber repetition-rate tunable gain-switched single-frequency Yb-doped fiber laser.

PubMed

Hou, Yubin; Zhang, Qian; Qi, Shuxian; Feng, Xian; Wang, Pu

2016-12-12

We report a monolithic gain-switched single-frequency Yb-doped fiber laser with widely tunable repetition rate. The single-frequency laser operation is realized by using an Yb-doped distributed Bragg reflection (DBR) fiber cavity, which is pumped by a commercial-available laser diode (LD) at 974 nm. The LD is electronically modulated by the driving current and the diode output contains both continuous wave (CW) and pulsed components. The CW component is set just below the threshold of the single-frequency fiber laser for reducing the requirement of the pump pulse energy. Above the threshold, the gain-switched oscillation is trigged by the pulsed component of the diode. Single-frequency pulsed laser output is achieved at 1.063 μm with a pulse duration of ~150 ns and a linewidth of 14 MHz. The repetition rate of the laser output can be tuned between 10 kHz and 400 kHz by tuning the electronic trigger signal. This kind of lasers shows potential for the applications in the area of coherent LIDAR etc.

Teachers' Pedagogical Reasoning and Reframing of Practice in Digital Contexts

ERIC Educational Resources Information Center

Holmberg, Jörgen; Fransson, Göran; Fors, Uno

2018-01-01

Purpose: The purpose of this paper is to advance the understanding of teachers' reframing of practice in digital contexts by analysing teachers' pedagogical reasoning processes as they explore ways of using information and communication technologies (ICT) to create added pedagogical value. Design/methodology/approach: A design-based research (DBR)…

Enculturating Seamless Language Learning through Artifact Creation and Social Interaction Process

ERIC Educational Resources Information Center

Wong, Lung-Hsiang; Chai, Ching Sing; Aw, Guat Poh; King, Ronnel B.

2015-01-01

This paper reports a design-based research (DBR) cycle of MyCLOUD (My Chinese ubiquitOUs learning Days). MyCLOUD is a seamless language learning model that addresses identified limitations of conventional Chinese language teaching, such as the decontextualized and unauthentic learning processes that usually hinder reflection and deep learning.…

5.5nm wavelength-tunable high-power MOPA diode laser system at 971 nm

NASA Astrophysics Data System (ADS)

Tawfieq, Mahmoud; Müller, André; Fricke, Jörg; Della Casa, Pietro; Ressel, Peter; Ginolas, Arnim; Feise, David; Sumpf, Bernd; Tränkle, Günther

2018-02-01

In this work, a widely tunable hybrid master oscillator power amplifier (MOPA) diode laser with 6.2 W of output power at 971.8 nm will be presented. The MO is a DBR laser, with a micro heater embedded on top of the DBR grating for wavelength tunability. The emitted light of the MO is collimated and coupled into a tapered amplifier using micro cylindrical lenses, all constructed on a compact 25 mm × 25 mm conduction cooled laser package. The MOPA system emits light with a measured spectral width smaller than 17 pm, limited by the spectrometer, and with a beam propagation factor of M2 1/e2 = 1.3 in the slow axis. The emission is thus nearly diffraction limited with 79% of the total power within the central lobe (4.9 W diffraction limited). The electrically controlled micro-heater provides up to 5.5 nm of wavelength tunability, up to a wavelength of 977.3 nm, while maintaining an output power variation of only +/- 0.16 % for the entire tuning range.

1.5  μm polarization-maintaining dual-wavelength single-frequency distributed Bragg reflection fiber laser with 28  GHz stable frequency difference.

PubMed

Hou, Yubin; Zhang, Qian; Qi, Shuxian; Feng, Xian; Wang, Pu

2018-03-15

We demonstrate a polarization-maintaining (PM) dual-wavelength (DW) single-frequency Er-doped distributed Bragg reflection (DBR) fiber laser with 28 GHz stable frequency difference. A homemade PM low-reflectivity superimposed fiber Bragg grating (SFBG) is employed as the output port of the DBR fiber laser. The SFBG has two reflection wavelengths located in the same grating region. The reflectivity of both DWs is around 85%. The achieved linear polarization extinction ratio is more than 20 dB. The DWs of the laser output are located at 1552.2 nm and 1552.43 nm, respectively. The optical signal-to-noise ratio (SNR) is above 60 dB. For each wavelength, only one longitudinal mode exists. The beat frequency of the two longitudinal modes is measured to be 28.4474 GHz, with the SNR of more than 65 dB and the linewidth less than 300 Hz. During a 60-min-long measurement, the standard deviation of the frequency fluctuation is 58.592 kHz.

Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong

2015-05-04

In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measuredmore » from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.« less

Broadband and wide-angle distributed Bragg reflectors based on amorphous germanium films by glancing angle deposition.

PubMed

Leem, Jung Woo; Yu, Jae Su

2012-08-27

We fabricated the distributed Bragg reflectors (DBRs) with amorphous germanium (a-Ge) films consisted of the same materials at a center wavelength (λc) of 1.33 μm by the glancing angle deposition. Their optical reflectance properties were investigated in the infrared wavelength region of 1-1.9 μm at incident light angles (θ inc) of 8-70°, together with the theoretical analysis using a rigorous coupled-wave analysis simulation. The two alternating a-Ge films at the incident vapor flux angles of 0 and 75° were formed as the high and low refractive index materials, respectively. The a-Ge DBR with only 5 periods exhibited a normalized stop bandwidth (∆λ/λ c) of ~24.1%, maintaining high reflectance (R) values of > 99%. Even at a high θ inc of 70°, the ∆λ/λ c was ~21.9%, maintaining R values of > 85%. The a-Ge DBR with good uniformity was obtained over the area of a 2 inch Si wafer. The calculated reflectance results showed a similar tendency to the measured data.

Group-III nitride VCSEL structures grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Ng, HockMin; Moustakas, Theodore D.

2000-07-01

III-nitride VCSEL structures designed for electron-beam pumping have been grown by molecular beam epitaxy (MBE). The structures consist of a sapphire substrate on which an AlN/GaN distributed Bragg reflector (DBR) with peak reflectance >99% at 402 nm is deposited. The active region consists of a 2-(lambda) cavity with 25 In0.1Ga0.9N/GaN multiquantum wells (MQWs) whose emission coincides with the high reflectance region of the DBR. The thicknesses of the InGaN wells and the GaN barriers are 35 angstrom and 75 angstrom respectively. The top reflector consists of a silver metallic mirror which prevents charging effects during electron-beam pumping. The structure was pumped from the top- side with a cw electron-beam using a modified cathodoluminescence (CL) system mounted on a scanning electron microscope chamber. Light output was collected from the polished sapphire substrate side. Measurements performed at 100 K showed intense emission at 407 nm with narrowing of the linewidth with increasing beam current. A narrow emission linewidth of 0.7 nm was observed indicating the onset of stimulated emission.

/III-V semiconductor broadband distributed Bragg reflectors for long-wavelength VCSEL and SESAM devices

NASA Astrophysics Data System (ADS)

Koeninger, Anna; Boehm, Gerhard; Meyer, Ralf; Amann, Markus-Christian

2014-12-01

Semiconductor devices such as vertical-cavity surface-emitting lasers (VCSELs) or semiconductor-saturable absorber mirrors (SESAMs) require high-reflection mirrors. Moreover, in VCSELs, it is beneficial to have a crystalline mirror, which is as thin as possible in order to ensure a high thermal conductivity for efficient heat-sinking of the laser. On the other hand, the wavelength tuning range of a SESAM is limited by the reflection bandwidth of its distributed Bragg reflector (DBR). Thus, broadband mirrors are preferable here. This paper reports a three-pair DBR grown by molecular beam epitaxy (MBE) using BaCaF2 and GaAs on a GaAs (100) substrate. Due to the high ratio in refractive indices of GaAs and the group-IIa-fluorides, high-reflectivity mirrors and wide bandwidths can be obtained with low total thicknesses. We also investigated growth and stability of the material BaCaF2, as well as its thermal conductivity both as single layer and Bragg reflector. Observed peeling of the layers could be avoided by implementing a fluorine treatment previous to the BaCaF2 growth.

Rethinking the distinction between black and brown carbon

NASA Astrophysics Data System (ADS)

Adler, G. A.; Franchin, A.; Lamb, K. D.; Manfred, K.; Middlebrook, A. M.; Schwarz, J. P.; Wagner, N.; Washenfelder, R. A.; Womack, C.; Murphy, D. M.

2017-12-01

Aerosol radiative properties contribute large uncertainty to modeling of the earth's radiative budget. Black carbon (BC) aerosols originate from combustion processes and substantially contribute to warming and uncertainty - ongoing efforts are focused on reducing their anthropogenic emissions even as their emissions from biomass burning sources, such as wildfire, may increase in the future. Quantifying the radiative effect of BC is challenging, in part due to its association with other light absorbing materials including Brown carbon organic aerosol (BrC) that absorbs primarily blue and ultraviolet light while BC absorbs broadly across the visible. Conventionally BrC is thought of a low volatility spherical particles, distinguishing it from BC, which has a distinctive agglomerate morphology and is refractory at high temperatures. However, the separation of BC and BrC is often operationally defined and dependent on the measurement method. Using measurements of aerosol morphology, mass, absorption, and refractory BC mass content we were able to identify a light absorbing contribution from biomass burning aerosol that does not correspond to either BC or BrC as conventionally defined. Our measurements were collected from realistic biomass burning fires at the Missoula Fire Sciences Laboratory as part of the NOAA FIREX project (2016) and from extensive natural wildfire sampled aloft during NASA SEAC4RS field study (2013). We coin the term Dark Brown Carbon (DBrC) to describe this material, which absorbs broadly across the visible and survives thermal denuding at 250°C but does not incandesce in laser induced incandesce (LII) measurements. DBrC may be an intermediate burning stage product between polycyclic aromatic hydrocarbons (PAHs) and the mature soot. DBrC deserves further study to quantify its abundance and aging in ambient biomass burning plumes, and its relationship to tar balls. Our findings show that more than half of the light absorption in biomass burning smoke could be potentially contributed to DBC, which may provide an explanation for some of the persistent inconsistencies in measurements of BC from biomass burning by different methods.

An iterative model for the steady state current distribution in oxide-confined vertical-cavity surface-emitting lasers (VCSELs)

NASA Astrophysics Data System (ADS)

Chuang, Hsueh-Hua

The purpose of this dissertation is to develop an iterative model for the analysis of the current distribution in vertical-cavity surface-emitting lasers (VCSELs) using a circuit network modeling approach. This iterative model divides the VCSEL structure into numerous annular elements and uses a circuit network consisting of resistors and diodes. The measured sheet resistance of the p-distributed Bragg reflector (DBR), the measured sheet resistance of the layers under the oxide layer, and two empirical adjustable parameters are used as inputs to the iterative model to determine the resistance of each resistor. The two empirical values are related to the anisotropy of the resistivity of the p-DBR structure. The spontaneous current, stimulated current, and surface recombination current are accounted for by the diodes. The lateral carrier transport in the quantum well region is analyzed using drift and diffusion currents. The optical gain is calculated as a function of wavelength and carrier density from fundamental principles. The predicted threshold current densities for these VCSELs match the experimentally measured current densities over the wavelength range of 0.83 mum to 0.86 mum with an error of less than 5%. This model includes the effects of the resistance of the p-DBR mirrors, the oxide current-confining layer and spatial hole burning. Our model shows that higher sheet resistance under the oxide layer reduces the threshold current, but also reduces the current range over which single transverse mode operation occurs. The spatial hole burning profile depends on the lateral drift and diffusion of carriers in the quantum wells but is dominated by the voltage drop across the p-DBR region. To my knowledge, for the first time, the drift current and the diffusion current are treated separately. Previous work uses an ambipolar approach, which underestimates the total charge transferred in the quantum well region, especially under the oxide region. However, the total result of the drift current and the diffusion current is less significant than the Ohmic current, especially in the cavity region. This simple iterative model is applied to commercially available oxide-confined VCSELs. The simulation results show excellent agreement with experimentally measured voltage-current curves (within 3.7% for a 10 mum and within 4% for a 5 mum diameter VCSEL) and light-current curves (within 2% for a 10 mum and within 9% for a 5 mum diameter VCSEL) curves and provides insight into the detailed distributions of current and voltage within a VCSEL. This difference between the theoretically calculated results and the measured results is less than the variation shown in the data sheets for production VCSELs.

Using Context-Aware Ubiquitous Learning to Support Students' Understanding of Geometry

ERIC Educational Resources Information Center

Crompton, Helen

2015-01-01

In this study, context-aware ubiquitous learning was used to support 4th grade students as they learn angle concepts. Context-aware ubiquitous learning was provided to students primarily through the use of iPads to access real-world connections and a Dynamic Geometry Environment. Gravemeijer and van Eerde's (2009), design-based research (DBR)…

A Seamless Learning Design for Mobile Assisted Language Learning: An Iranian Context

ERIC Educational Resources Information Center

Foomani, Elham Mohammadi; Hedayati, Mohsen

2016-01-01

Recent developments in information communication technology (ICT) have resulted in a paradigm shift in e-Learning and there is a growing interest in developing design-based research (DBR) focusing on learners and their involvement in knowledge sharing in a contextualized mode. The present study reports a mobile-assisted language learning (MALL)…

Developing a Framework for Social Technologies in Learning via Design-Based Research

ERIC Educational Resources Information Center

Parmaxi, Antigoni; Zaphiris, Panayiotis

2015-01-01

This paper reports on the use of design-based research (DBR) for the development of a framework that grounds the use of social technologies in learning. The paper focuses on three studies which step on the learning theory of constructionism. Constructionism assumes that knowledge is better gained when students find this knowledge for themselves…

A Design Based Research Framework for Implementing a Transnational Mobile and Blended Learning Solution

ERIC Educational Resources Information Center

Palalas, Agnieszka; Berezin, Nicole; Gunawardena, Charlotte; Kramer, Gretchen

2015-01-01

The article proposes a modified Design-Based Research (DBR) framework which accommodates the various socio-cultural factors that emerged in the longitudinal PA-HELP research study at Central University College (CUC) in Ghana, Africa. A transnational team of stakeholders from Ghana, Canada, and the USA collaborated on the development,…

Using Diagrams versus Text for Spaced Restudy: Effects on Learning in 10th Grade Biology Classes

ERIC Educational Resources Information Center

Bergey, Bradley W.; Cromley, Jennifer G.; Kirchgessner, Mandy L.; Newcombe, Nora S.

2015-01-01

Background and Aim: Spaced restudy has been typically tested with written learning materials, but restudy with visual representations in actual classrooms is under-researched. We compared the effects of two spaced restudy interventions: A Diagram-Based Restudy (DBR) warm-up condition and a business-as-usual Text-Based Restudy (TBR) warm-up…

Revision and Validation of a Culturally-Adapted Online Instructional Module Using Edmundson's CAP Model: A DBR Study

ERIC Educational Resources Information Center

Tapanes, Marie A.

2011-01-01

In the present study, the Cultural Adaptation Process Model was applied to an online module to include adaptations responsive to the online students' culturally-influenced learning styles and preferences. The purpose was to provide the online learners with a variety of course material presentations, where the e-learners had the opportunity to…

Development of a Design-Based Learning Curriculum through Design-Based Research for a Technology-Enabled Science Classroom

ERIC Educational Resources Information Center

Kim, Paul; Suh, Esther; Song, Donggil

2015-01-01

This exploratory study provides a deeper look into the aspects of students' experience from design-based learning (DBL) activities for fifth grade students. Using design-based research (DBR), this study was conducted on a series of science learning activities leveraging mobile phones with relevant applications and sensors. We observed 3 different…

Design Refinement Tools for a Teacher Education Curriculum: The Example of a Service Learning Course

ERIC Educational Resources Information Center

Petersen, Nadine; Henning, Elizabeth

2010-01-01

This article addresses the issue of the theory-practice divide in pre-service teacher education from the viewpoint of design-based research (DBR). Using the example of a course in service learning (SL), the authors discuss their reflection on a curriculum that failed to help the students convert declarative knowledge to procedures of pedagogy, or…

Development and Validation of a Web-Based Module to Teach Metacognitive Learning Strategies to Students in Higher Education

ERIC Educational Resources Information Center

Singh, Oma B.

2009-01-01

This study used a design based-research (DBR) methodology to examine how an Instructional Systematic Design (ISD) process such as ADDIE (Analysis, Design, Development, Implementation, Evaluation) can be employed to develop a web-based module to teach metacognitive learning strategies to students in higher education. The goal of the study was…

Open Source Software and Design-Based Research Symbiosis in Developing 3D Virtual Learning Environments: Examples from the iSocial Project

ERIC Educational Resources Information Center

Schmidt, Matthew; Galyen, Krista; Laffey, James; Babiuch, Ryan; Schmidt, Carla

2014-01-01

Design-based research (DBR) and open source software are both acknowledged as potentially productive ways for advancing learning technologies. These approaches have practical benefits for the design and development process and for building and leveraging community to augment and sustain design and development. This report presents a case study of…

Generation of spectrally stable continuous-wave emission and ns pulses with a peak power of 4 W using a distributed Bragg reflector laser and a ridge-waveguide power amplifier.

PubMed

Klehr, A; Wenzel, H; Fricke, J; Bugge, F; Erbert, G

2014-10-06

We have developed a diode-laser based master oscillator power amplifier (MOPA) light source which emits high-power spectrally stabilized and nearly-diffraction limited optical pulses in the nanoseconds range as required by many applications. The MOPA consists of a distributed Bragg reflector (DBR) laser as master oscillator driven by a constant current and a ridge waveguide power amplifier (PA) which can be driven by a constant current (DC) or by rectangular current pulses with a width of 5 ns at a repetition frequency of 200 kHz. Under pulsed operation the amplifier acts as an optical gate, converting the CW input beam emitted by the DBR laser into a train of short amplified optical pulses. With this experimental MOPA arrangement no relaxation oscillations occur. A continuous wave power of 1 W under DC injection and a pulse power of 4 W under pulsed operation are reached. For both operational modes the optical spectrum of the emission of the amplifier exhibits a peak at a constant wavelength of 973.5 nm with a spectral width < 10 pm.

Frequency stability of a dual wavelength quantum cascade laser.

PubMed

Sergachev, Ilia; Maulini, Richard; Gresch, Tobias; Blaser, Stéphane; Bismuto, Alfredo; Müller, Antoine; Bidaux, Yves; Südmeyer, Thomas; Schilt, Stéphane

2017-05-15

We characterized the dual wavelength operation of a distributed Bragg reflector (DBR) quantum cascade laser (QCL) operating at 4.5 μm using two independent optical frequency discriminators. The QCL emits up to 150 mW fairly evenly distributed between two adjacent Fabry-Perot modes separated by ≈11.6 GHz. We show a strong correlation between the instantaneous optical frequencies of the two lasing modes, characterized by a Pearson correlation coefficient of 0.96. As a result, we stabilized one laser mode of the QCL to a N 2 O transition using a side-of-fringe locking technique, reducing its linewidth by a factor 6.2, from 406 kHz in free-running operation down to 65 kHz (at 1-ms observation time), and observed a simultaneous reduction of the frequency fluctuations of the second mode by a similar amount, resulting in a linewidth narrowing by a factor 5.4, from 380 kHz to 70 kHz. This proof-of-principle demonstration was performed with a standard DBR QCL that was not deliberately designed for dual-mode operation. These promising results open the door to the fabrication of more flexible dual-mode QCLs with the use of specifically designed gratings in the future.

Efficient green lasers for high-resolution scanning micro-projector displays

NASA Astrophysics Data System (ADS)

Bhatia, Vikram; Bauco, Anthony S.; Oubei, Hassan M.; Loeber, David A. S.

2010-02-01

Laser-based projectors are gaining increased acceptance in mobile device market due to their low power consumption, superior image quality and small size. The basic configuration of such micro-projectors is a miniature mirror that creates an image by raster scanning the collinear red, blue and green laser beams that are individually modulated on a pixel-bypixel basis. The image resolution of these displays can be limited by the modulation bandwidth of the laser sources, and the modulation speed of the green laser has been one of the key limitations in the development of these displays. We will discuss how this limitation is fundamental to the architecture of many laser designs and then present a green laser configuration which overcomes these difficulties. In this green laser architecture infra-red light from a distributed Bragg-reflector (DBR) laser diode undergoes conversion to green light in a waveguided second harmonic generator (SHG) crystal. The direct doubling in a single pass through the SHG crystal allows the device to operate at the large modulation bandwidth of the DBR laser. We demonstrate that the resultant product has a small footprint (<0.7 cc envelope volume), high efficiency (>9% electrical-to-optical conversion) and large modulation bandwidth (>100 MHz).

Development and exemplification of a model for Teacher Assessment in Primary Science

NASA Astrophysics Data System (ADS)

Davies, D. J.; Earle, S.; McMahon, K.; Howe, A.; Collier, C.

2017-09-01

The Teacher Assessment in Primary Science project is funded by the Primary Science Teaching Trust and based at Bath Spa University. The study aims to develop a whole-school model of valid, reliable and manageable teacher assessment to inform practice and make a positive impact on primary-aged children's learning in science. The model is based on a data-flow 'pyramid' (analogous to the flow of energy through an ecosystem), whereby the rich formative assessment evidence gathered in the classroom is summarised for monitoring, reporting and evaluation purposes [Nuffield Foundation. (2012). Developing policy, principles and practice in primary school science assessment. London: Nuffield Foundation]. Using a design-based research (DBR) methodology, the authors worked in collaboration with teachers from project schools and other expert groups to refine, elaborate, validate and operationalise the data-flow 'pyramid' model, resulting in the development of a whole-school self-evaluation tool. In this paper, we argue that a DBR approach to theory-building and school improvement drawing upon teacher expertise has led to the identification, adaptation and successful scaling up of a promising approach to school self-evaluation in relation to assessment in science.

Electrically-pumped 850-nm micromirror VECSELs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith

Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission ismore » employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.« less

Electrically pumped 850-nm micromirror VECSELs

NASA Astrophysics Data System (ADS)

Keeler, Gordon A.; Serkland, Darwin K.; Geib, Kent M.; Peake, Gregory M.; Mar, Alan

2005-03-01

Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

All-semiconductor high-speed akinetic swept-source for OCT

NASA Astrophysics Data System (ADS)

Minneman, Michael P.; Ensher, Jason; Crawford, Michael; Derickson, Dennis

2011-12-01

A novel swept-wavelength laser for optical coherence tomography (OCT) using a monolithic semiconductor device with no moving parts is presented. The laser is a Vernier-Tuned Distributed Bragg Reflector (VT-DBR) structure exhibiting a single longitudinal mode. All-electronic wavelength tuning is achieved at a 200 kHz sweep repetition rate, 20 mW output power, over 100 nm sweep width and coherence length longer than 40 mm. OCT point-spread functions with 45- 55 dB dynamic range are demonstrated; lasers at 1550 nm, and now 1310 nm, have been developed. Because the laser's long-term tuning stability allows for electronic sample trigger generation at equal k-space intervals (electronic k-clock), the laser does not need an external optical k-clock for measurement interferometer sampling. The non-resonant, allelectronic tuning allows for continuously adjustable sweep repetition rates from mHz to 100s of kHz. Repetition rate duty cycles are continuously adjustable from single-trigger sweeps to over 99% duty cycle. The source includes a monolithically integrated power leveling feature allowing flat or Gaussian power vs. wavelength profiles. Laser fabrication is based on reliable semiconductor wafer-scale processes, leading to low and rapidly decreasing cost of manufacture.

Designs that Fly: What the History of Aeronautics Tells Us about the Future of Design-Based Research in Education

ERIC Educational Resources Information Center

O'Neill, D. Kevin

2012-01-01

For almost two decades, there has been growing interest in what design-based research (DBR) can contribute to both educational practice and theory. Since its introduction into the literature, this orientation to educational research has repeatedly been likened to aeronautical engineering as a way to clarify its nature and argue its potential. This…

The Motivating Power of Social Obligation: An Investigation into the Pedagogical Affordances of Mobile Learning Integrated with Facebook

ERIC Educational Resources Information Center

Sazalli, Nurhasmiza; Wegerif, Rupert; Kleine-Staarman, Judith

2014-01-01

We report on the provisional findings of an ongoing research project investigating the pedagogical affordances of mobile learning in combination with Web 2.0 tools for the learning of English for English as a Second Language (ESL) learners. Using Design Based Research (DBR) as an approach to conduct this study, this paper will first present the…

Coherent perfect rotation theory: connections with, and consequences beyond, the anti-laser

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Andrews, James; Zhou, Chuanhong; Baker, Michael

2014-05-01

Coherent Perfect Rotation (CPR) phenomena are a reversible generalization of the anti-laser. By evaluating CPR in a broad variety of common optical systems, including optical cavities and DFB and DBR structures, we illustrate its unique threshold and resonance features. This study builds intuition critical to assessing the utility of CPR in optical devices, and we detail it in a concrete application.

Laser Setup for Volume Diffractive Optical Elements Recording in Photo-Thermo-Refractive Glass

DTIC Science & Technology

2016-04-14

Total Number: PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number: Sub Contractors (DD882) Names of...3 1b 2 3 a b Fig. 14. Schematic of a DBR (a) and DFB (b) lasers in Yb doped PTR glass. 1a and 1b – dichroic beam splitters with HR at 1066 nm and HT

DETECTION OF K-RAS AND P53 MUTATIONS IN SPUTUM SAMPLES OF LUNG CANCER PATIENTS USING LASER CAPTURE MICRODISSECTION MICROSCOPE AND MUTATION ANALYSIS

EPA Science Inventory

Detection of K-ras and p53 Mutations in Sputum Samples of Lung Cancer Patients Using Laser Capture Microdissection Microscope and Mutation Analysis

Phouthone Keohavong a,*, Wei-Min Gao a, Kui-Cheng Zheng a, Hussam Mady b, Qing Lan c, Mona Melhem b, and Judy Mumford d.
<...

InGaAsN/GaAs Heterostructures for Long-Wavelength Light-Emitting Devices

DTIC Science & Technology

2000-06-23

vertical cavity surface emitting lasers ( VCSELs ) on GaAs is expected to be possible by... molecular beam epitaxy using an RF plasma-source. Broad area and ridge waveguide laser structures based on such QWs exhibit performance that can...work with GaAs/AlAs DBR-mirrors is expected to lead to novel vertical cavity lasers for optical fiber communication systems. Acknowledgement

Visible Vertical Cavity Surface Emitting Lasers

DTIC Science & Technology

1993-01-01

circular output beams are easily coupled into optical fibers, or focused or collimated with microlenslets. The VCSELs can be tested individually at the wafer...semiconductor visible VCSEL . Also shown is the DBR reflectance and reflectivity phase , as seen from the optical cavity, and the electric field intensity ...76 xv Figure page 2.32 Calculated electric field intensity for the example IR and visible VCSELs shown in Fig. 2.31 ........................... 79

Designing and Scaling Highly Effective Interventions That Produce BIG Improvement: "Counter-Intuitive Lessons from the Higher Order Thinking Skills (HOTS) Project." Conference Paper

ERIC Educational Resources Information Center

Pogrow, Stanley

2015-01-01

There is little discussion in the Design-Based Research (DBR) literature on how to design an intervention that has the potential to be highly effective. The act of designing is usually viewed as engineering something from theory or research on best practices. This paper challenges that universal belief and presents successful design as an…

Flipped Instruction in English Language Teacher Education: A Design-­Based Study in a Complex, Open-­Ended Learning Environment

ERIC Educational Resources Information Center

Egbert, Joy; Herman, David; Lee, HyunGyung

2015-01-01

Reports of flipped classrooms across areas in the field of ESL are rare, and those that address the complexities of ESL teacher education, particularly the methods course in which procedural knowledge is privileged over declarative knowledge, are even rarer. This paper uses a design-­-based research (DBR) approach to explore the flip of an ESL…

Cancellation of birefringence in DBR laser through principal axis offset by a rotation of 90°

NASA Astrophysics Data System (ADS)

Zaini, M. K. A.; Lai, M. H.; Islam, M. R.; Lim, K. S.; Ahmad, H.

2018-04-01

The cancellation of birefringence in the distributed Bragg reflector based on 90° rotation offset method is demonstrated. It is found that the birefringence, which causes the peak bifurcation has been eliminated and a single peak is produced at each resonance in the output spectrum. This modification is an economic solution for eliminating the birefringence of the optical fibre devices.

Wavelet-based analysis of transient electromagnetic wave propagation in photonic crystals.

PubMed

Shifman, Yair; Leviatan, Yehuda

2004-03-01

Photonic crystals and optical bandgap structures, which facilitate high-precision control of electromagnetic-field propagation, are gaining ever-increasing attention in both scientific and commercial applications. One common photonic device is the distributed Bragg reflector (DBR), which exhibits high reflectivity at certain frequencies. Analysis of the transient interaction of an electromagnetic pulse with such a device can be formulated in terms of the time-domain volume integral equation and, in turn, solved numerically with the method of moments. Owing to the frequency-dependent reflectivity of such devices, the extent of field penetration into deep layers of the device will be different depending on the frequency content of the impinging pulse. We show how this phenomenon can be exploited to reduce the number of basis functions needed for the solution. To this end, we use spatiotemporal wavelet basis functions, which possess the multiresolution property in both spatial and temporal domains. To select the dominant functions in the solution, we use an iterative impedance matrix compression (IMC) procedure, which gradually constructs and solves a compressed version of the matrix equation until the desired degree of accuracy has been achieved. Results show that when the electromagnetic pulse is reflected, the transient IMC omits basis functions defined over the last layers of the DBR, as anticipated.

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

PubMed Central

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-01-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications. PMID:26245759

Double high refractive-index contrast grating VCSEL

NASA Astrophysics Data System (ADS)

Gebski, Marcin; Dems, Maciej; Wasiak, Michał; Sarzała, Robert P.; Lott, J. A.; Czyszanowski, Tomasz

2015-03-01

Distributed Bragg reflectors (DBRs) are typically used as the highly reflecting mirrors of vertical-cavity surface-emitting lasers (VCSELs). In order to provide optical field confinement, oxide apertures are often incorporated in the process of the selective wet oxidation of high aluminum-content DBR layers. This technology has some potential drawbacks such as difficulty in controlling the uniformity of the oxide aperture diameters across a large-diameter (≥ 6 inch) production wafers, high DBR series resistance especially for small diameters below about 5 μm despite elaborate grading and doping schemes, free carrier absorption at longer emission wavelengths in the p-doped DBRs, reduced reliability for oxide apertures placed close to the quantum wells, and low thermal conductivity for transporting heat away from the active region. A prospective alternative mirror is a high refractive index contrast grating (HCG) monolithically integrated with the VCSEL cavity. Two HCG mirrors potentially offer a very compact and simplified VCSEL design although the problems of resistance, heat dissipation, and reliability are not completely solved. We present an analysis of a double HCG 980 nm GaAs-based ultra-thin VCSEL. We analyze the optical confinement of such a structure with a total optical thickness is ~1.0λ including the optical cavity and the two opposing and parallel HCG mirrors.

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

NASA Astrophysics Data System (ADS)

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-08-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications.

Picosecond pulsed micro-module emitting near 560 nm using a frequency doubled gain-switched DBR ridge waveguide semiconductor laser

NASA Astrophysics Data System (ADS)

Kaltenbach, André; Hofmann, Julian; Seidel, Dirk; Lauritsen, Kristian; Bugge, Frank; Fricke, Jörg; Paschke, Katrin; Erdmann, Rainer; Tränkle, Günther

2017-02-01

A miniaturized picosecond pulsed semiconductor laser source in the spectral range around 560nm is realized by integrating a frequency doubled distributed Bragg reflector ridge waveguide laser (DBR-RWL) into a micromodule. Such compact laser sources are suitable for mobile application, e.g. in microscopes. The picosecond optical pulses are generated by gain-switching which allows for arbitrary pulse repetition frequencies. For frequency conversion a periodically poled magnesium doped lithium niobate ridge waveguide crystal (PPLN) is used to provide high conversion efficiency with single-pass second harmonic generation (SHG). The coupling of the pulsed radiation into the PPLN crystal is realized by a GRIN-lens. Such types of lenses collect the divergent laser radiation and focus it into the crystal waveguide providing high coupling efficiency at a minimum of space compared to the usage of fast axis collimator(FAC)/slow axis collimator (SAC) lens combinations. The frequency doubled output pulses show a pulse width of about 60 ps FWHM and a spectral width around 0.06nm FWHM at a central wavelength of 557nm at 15Å. The pulse peak power could be determined to be more than 300mW at a repetition frequency of 40 MHz.

Deformation near the Casa Diablo geothermal well field and related processes Long Valley caldera, Eastern California, 1993-2000

USGS Publications Warehouse

Howle, J.F.; Langbein, J.O.; Farrar, C.D.; Wilkinson, S.K.

2003-01-01

Regional first-order leveling lines, which extend from Lee Vining, CA, to Tom's Place, CA, have been surveyed periodically since 1957 by the U.S. Geological Survey (USGS), the National Geodetic Survey (NGS), and Caltrans. Two of the regional survey lines, or leveling networks, intersect at the Casa Diablo geothermal well field. These leveling networks, referenced to a distant bench mark (C916) near Lee Vining, provide time-series vertical control data of land-surface deformation that began around 1980. These data are also useful for delineating localized subsidence at Casa Diablo related to reservoir pressure and temperature changes owing to geothermal development that began in 1985. A comparison of differences in bench-mark elevations for five time periods between 1983 and 1997 shows the development and expansion of a subsidence bowl at Casa Diablo. The subsidence coincides spatially with the geothermal well field and temporally with the increased production rates and the deepening of injection wells in 1991, which resulted in an increase in the rate of pressure decline. The subsidence, superimposed on a broad area of uplift, totaled about 310 mm by 1997. The USGS established orthogonal tilt arrays in 1983 to better monitor deformation across the caldera. One tilt array (DBR) was established near what would later become the Casa Diablo geothermal well field. This array responded to magmatic intrusions prior to geothermal development, tilting away from the well field. With the start of geothermal fluid extraction in 1985, tilt at the DBR array reversed direction and began tilting into the well field. In 1991, geothermal power production was increased by a factor of four, and reservoir pressures began a period of steep decline. These changes caused a temporary three-fold increase in the tilt rate. The tilt rate became stable in 1993 and was about 40% lower than that measured in 1991-1992, but still greater than the rates measured during 1985-1990. Data from the local leveling networks spanning the well field and the bounding graben were analyzed for several 2-year periods (1993-1995, 1995-1997, and 1997-1999). Annual rates of change across the normal faults bounding the graben have steadily decreased for each 2-year period between 1993 and 1999, reflecting the slowing decline in geothermal reservoir pressure. Horizontal control data from a two-color electronic distance meter (EDM) defined the lateral extent of subsidence at Casa Diablo. The EDM and leveling data elucidate the localized effect of the shallow source of subsidence and the broader effect of the deeper magmatic inflation source. Data from bench marks common to both the vertical and the horizontal control networks were used to assess the effect of subsidence on the EDM base station (CASA). Modeling of geodetic data collected during periods of little or no magmatic inflation indicated that the CASA two-color EDM station is being drawn toward the well field at a rate of 3-5 mm/yr. ?? 2003 Elsevier B.V. All rights reserved.

Deuterium Substitution used as a Tool for Investigating Mechanisms of Gas-Phase Free-Radical Reactions

NASA Technical Reports Server (NTRS)

Wine, P. H.; Hynes, A. J.; Nicovich, J. M.

1997-01-01

Results are presented and discussed for a number of gas phase free radical reactions where H/D isotope effects provide valuable mechanistic insights. The cases considered are (1) the reactions of OH, NO3, and Cl with atmospheric reduced sulfur compounds, (2) the reactions of OH and OD with CH3CN and CD3CN, and (3) the reactions of alkyl radicals with HBr and DBr.

Optomechanical Coatings for High-Power Mirrors and Adaptive Optics

DTIC Science & Technology

2009-03-24

micromirror under illumination is to increase the reflectance of the mirror. A multi-layer dielectric mirror becomes a necessity at moderate to high energies...structure. This technique was successfully demonstrated on a micromirror array fabricated by Sandia National Laboratory. Fig. 2-(1) shows the curvature of...a micromirror roughly 500 1-1m in diameter under varying laser illumination, with and without a 3-pair DBR mirror designed and fabricated by our

Latest Progress in High Power VECSELs

DTIC Science & Technology

2013-01-01

are more efficient, and can be tailored to an application. In this manuscript we lay out some advantages to VECSELs as compared to many in-plane...semiconductor lasers. We review common fabrication and packaging techniques in Section 2. In Section 3, we discuss both small- signal and large-signal... out LR coating MQW DBR VECSEL chip Heat Spreader output coupler HR flat mirror BF at Brewster’s angle HR flat mirror HR curved mirror signal beam out

Fiber-based laser MOPA transmitter packaging for space environment

NASA Astrophysics Data System (ADS)

Stephen, Mark; Yu, Anthony; Chen, Jeffrey; Numata, Kenji; Wu, Stewart; Gonzales, Brayler; Han, Lawrence; Fahey, Molly; Plants, Michael; Rodriguez, Michael; Allan, Graham; Abshire, James; Nicholson, Jeffrey; Hariharan, Anand; Mamakos, William; Bean, Brian

2018-02-01

NASA's Goddard Space Flight Center has been developing lidar to remotely measure CO2 and CH4 in the Earth's atmosphere. The ultimate goal is to make space-based satellite measurements with global coverage. We are working on maturing the technology readiness of a fiber-based, 1.57-micron wavelength laser transmitter designed for use in atmospheric CO2 remote-sensing. To this end, we are building a ruggedized prototype to demonstrate the required power and performance and survive the required environment. We are building a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture. The laser is a wavelength-locked, single frequency, externally modulated DBR operating at 1.57-micron followed by erbium-doped fiber amplifiers. The last amplifier stage is a polarization-maintaining, very-large-mode-area fiber with 1000 μm2 effective area pumped by a Raman fiber laser. The optical output is single-frequency, one microsecond pulses with >450 μJ pulse energy, 7.5 KHz repetition rate, single spatial mode, and < 20 dB polarization extinction.

Improvements to III-nitride light-emitting diodes through characterization and material growth

NASA Astrophysics Data System (ADS)

Getty, Amorette Rose Klug

A variety of experiments were conducted to improve or aid the improvement of the efficiency of III-nitride light-emitting diodes (LEDs), which are a critical area of research for multiple applications, including high-efficiency solid state lighting. To enhance the light extraction in ultraviolet LEDs grown on SiC substrates, a distributed Bragg reflector (DBR) optimized for operation in the range from 250 to 280 nm has been developed using MBE growth techniques. The best devices had a peak reflectivity of 80% with 19.5 periods, which is acceptable for the intended application. DBR surfaces were sufficiently smooth for subsequent epitaxy of the LED device. During the course of this work, pros and cons of AlGaN growth techniques, including analog versus digital alloying, were examined. This work highlighted a need for more accurate values of the refractive index of high-Al-content AlxGa1-xNin the UV wavelength range. We present refractive index results for a wide variety of materials pertinent to the fabrication of optical III-nitride devices. Characterization was done using Variable-Angle Spectroscopic Ellipsometry. The three binary nitrides, and all three ternaries, have been characterized to a greater or lesser extent depending on material compositions available. Semi-transparent p-contact materials and other thin metals for reflecting contacts have been examined to allow optimization of deposition conditions and to allow highly accurate modeling of the behavior of light within these devices. Standard substrate materials have also been characterized for completeness and as an indicator of the accuracy of our modeling technique. We have demonstrated a new technique for estimating the internal quantum efficiency (IQE) of nitride light-emitting diodes. This method is advantageous over the standard low-temperature photoluminescence-based method of estimating IQE, as the new method is conducted under the same conditions as normal device operation. We have developed processing techniques and have characterized patternable absorbing materials which eliminate scattered light within the device, allowing an accurate simulation of the device extraction efficiency. This efficiency, with measurements of the input current and optical output power, allow a straightforward calculation of the IQE. Two sets of devices were measured, one of material grown in-house, with a rough p-GaN surface, and one of commercial LED material, with smooth interfaces and very high internal quantum efficiency.

Simulation of Optical Resonators for Vertical-Cavity Surface-Emitting Lasers (vcsel)

NASA Astrophysics Data System (ADS)

Mansour, Mohy S.; Hassen, Mahmoud F. M.; El-Nozahey, Adel M.; Hafez, Alaa S.; Metry, Samer F.

2010-04-01

Simulation and modeling of the reflectivity and transmissivity of the multilayer DBR of VCSEL, as well as inside the active region quantum well are analyzed using the characteristic matrix method. The electric field intensity distributions inside such vertical-cavity structure are calculated. A software program under MATLAB environment is constructed for the simulation. This study was performed for two specific Bragg wavelengths 980 nm and 370 nm for achieving a resonant periodic gain (RPG)

Joint Services Electronics Program. Basic Research in Electronics (JSEP)

DTIC Science & Technology

1992-08-01

DBRs). Our DBR work allows us to develop improved vertical cavity surface-emitting lasers ( VCSELs ) and also to examine details of optical phenomena... in short-cavity lasers. We have used MBE regrowth techniques to provide current tunnelling into the device active region of the VCSEL . We use an AlAs... optical detector structures. We have already developed significant capability in the low temperature (2506C - 3000C) growth of undoped GaAs and AIo.3Gao

High-frequency ultrasound for monitoring changes in liver tissue during preservation

NASA Astrophysics Data System (ADS)

Vlad, Roxana M.; Czarnota, Gregory J.; Giles, Anoja; Sherar, Michael D.; Hunt, John W.; Kolios, Michael C.

2005-01-01

Currently the only method to assess liver preservation injury is based on liver appearance and donor medical history. Previous work has shown that high-frequency ultrasound could detect ischemic cell death due to changes in cell morphology. In this study, we use high-frequency ultrasound integrated backscatter to assess liver damage in experimental models of liver ischemia. Ultimately, our goal is to predict organ suitability for transplantation using high-frequency imaging and spectral analysis techniques. To examine the effects of liver ischemia at different temperatures, livers from Wistar rats were surgically excised, immersed in phosphate buffer saline and stored at 4 and 20 °C for 24 h. To mimic organ preservation, livers were excised, flushed with University of Wisconsin (UW) solution and stored at 4 °C for 24 h. Preservation injury was simulated by either not flushing livers with UW solution or, before scanning, allowing livers to reach room temperature. Ultrasound images and corresponding radiofrequency data were collected over the ischemic period. No significant increase in integrated backscatter (~2.5 dBr) was measured for the livers prepared using standard preservation conditions. For all other ischemia models, the integrated backscatter increased by 4-9 dBr demonstrating kinetics dependent on storage conditions. The results provide a possible framework for using high-frequency imaging to non-invasively assess liver preservation injury.

OPS laser EPI design for different wavelengths

NASA Astrophysics Data System (ADS)

Moloney, J. V.; Hader, J.; Li, H.; Kaneda, Y.; Wang, T. S.; Yarborough, M.; Koch, S. W.; Stolz, W.; Kunert, B.; Bueckers, C.; Chaterjee, S.; Hardesty, G.

2009-02-01

Design of optimized semiconductor optically-pumped semiconductor lasers (OPSLs) depends on many ingredients starting from the quantum wells, barrier and cladding layers all the way through to the resonant-periodic gain (RPG) and high reflectivity Bragg mirror (DBR) making up the OPSL active mirror. Accurate growth of the individual layers making up the RPG region is critical if performance degradation due to cavity misalignment is to be avoided. Optimization of the RPG+DBR structure requires knowledge of the heat generation and heating sinking of the active mirror. Nonlinear Control Strategies SimuLaseTM software, based on rigorous many-body calculations of the semiconductor optical response, allows for quantum well and barrier optimization by correlating low intensity photoluminescence spectra computed for the design, with direct experimentally measured wafer-level edge and surface PL spectra. Consequently, an OPSL device optimization procedure ideally requires a direct iterative interaction between designer and grower. In this article, we discuss the application of the many-body microscopic approach to OPSL devices lasing at 850nm, 1040nm and 2μm. The latter device involves and application of the many-body approach to mid-IR OPSLs based on antimonide materials. Finally we will present results on based on structural modifications of the epitaxial structure and/or novel material combinations that offer the potential to extend OPSL technology to new wavelength ranges.

AaEIN3 Mediates the Downregulation of Artemisinin Biosynthesis by Ethylene Signaling Through Promoting Leaf Senescence in Artemisia annua.

PubMed

Tang, Yueli; Li, Ling; Yan, Tingxiang; Fu, Xueqing; Shi, Pu; Shen, Qian; Sun, Xiaofen; Tang, Kexuan

2018-01-01

Artemisinin is an important drug for malaria treatment, which is exclusively produced in Artemisia annua . It's important to dissect the regulatory mechanism of artemisinin biosynthesis by diverse plant hormones and transcription factors. Our study shows ethylene, a plant hormone which accelerates flower and leaf senescence and fruit ripening, suppressed the expression of genes encoding three key enzymes ADS, DBR2, CYP71AV1, and a positive regulator AaORA involved in artemisinin biosynthesis. Then we isolated the gene encoding ETHYLENE-INSENSITIVE3 (EIN3), a key transcription factor in ethylene signaling pathway, by screening the transcriptome and genome database from Artemisia annua , named AaEIN3 . Overexpressing AaEIN3 suppressed artemisinin biosynthesis, while repressing its expression with RNAi enhanced artemisinin biosynthesis in Artemisia annua , indicating AaEIN3 negatively regulates artemisinin biosynthesis. Further study showed the downregulation of artemisinin biosynthesis by ethylene required the mediation of AaEIN3. AaEIN3 could accelerate leaf senescence, and leaf senescence attenuated the expression of ADS, DBR2, CYP71AV1 , and AaORA that are involved in artemisinin biosynthesis. Collectively, our study demonstrated a negative correlation between ethylene signaling and artemisinin biosynthesis, which is ascribed to AaEIN3-induced senescence process of leaves. Our work provided novel knowledge on the regulatory network of plant hormones for artemisinin metabolic pathway.

Engagement of Components of DNA-Break Repair Complex and NFκB in Hsp70A1A Transcription Upregulation by Heat Shock.

PubMed

Hazra, Joyita; Mukherjee, Pooja; Ali, Asif; Poddar, Soumita; Pal, Mahadeb

2017-01-01

An involvement of components of DNA-break repair (DBR) complex including DNA-dependent protein kinase (DNA-PK) and poly-ADP-ribose polymerase 1 (PARP-1) in transcription regulation in response to distinct cellular signalling has been revealed by different laboratories. Here, we explored the involvement of DNA-PK and PARP-1 in the heat shock induced transcription of Hsp70A1A. We find that inhibition of both the catalytic subunit of DNA-PK (DNA-PKc), and Ku70, a regulatory subunit of DNA-PK holo-enzyme compromises transcription of Hsp70A1A under heat shock treatment. In immunoprecipitation based experiments we find that Ku70 or DNA-PK holoenzyme associates with NFκB. This NFκB associated complex also carries PARP-1. Downregulation of both NFκB and PARP-1 compromises Hsp70A1A transcription induced by heat shock treatment. Alteration of three bases by site directed mutagenesis within the consensus κB sequence motif identified on the promoter affected inducibility of Hsp70A1A transcription by heat shock treatment. These results suggest that NFκB engaged with the κB motif on the promoter cooperates in Hsp70A1A activation under heat shock in human cells as part of a DBR complex including DNA-PK and PARP-1.

Venus surface optical imaging from a balloon or a probe during descent : Monte Carlo simulation and the proposal of the experiment on TV-camera in transparency windows of a 1.02 and 0.85 microns

NASA Astrophysics Data System (ADS)

Ekonomov, A.

2011-10-01

The problem of imaging of the planet surfaces is a priority for space exploration, since the surface is crucial to study the origin mechanisms . However, if for other planets in the solar system conducted hundreds of experiments in this direction, for Venus there are only a few . This is due to an optically dense cloud cover in the upper atmosphere of Venus. Until now, the global picture is obtained only in radio wavelengths. First spacecraft to the board which was carried out large-scale location of Venus was on the Pioneer Venus Orbiter (1978), which carried out radar mapping of the surface. AMS Venus 15/16 (1978) have got on board the DBR with a resolution of 1-2 km, and Magellan (1989) had a DBR with a resolution of 100 m. During 1975-1982 Soviet leanders, being on a surface, have taken a number of panoramas with the high resolution of the order of shares of meter. Thus, there is a gap between the resolution of 100 m and shares of meter and it should be filled. Such experiment could be imaging from undercloud layer in a transparency window of 1 microns. Idea is not new, but technical study was not conducted.

Venus surface optical imaging from a balloon or a probe during descent : Monte Carlo simulation and the proposal of the experiment on TV-camera in transparency windows of a 1.02 and 0.85 microns.

NASA Astrophysics Data System (ADS)

Ekonomov, A.

2011-10-01

The problem of imaging of the planet surfaces is a priority for space exploration, since the surface is crucial to study the origin mechanisms . However, if for other planets in the solar system conducted hundreds of experiments in this direction, for Venus there are only a few . This is due to an optically dense cloud cover in the upper atmosphere of Venus. Until now, the global picture is obtained only in radio wavelengths. First spacecraft to the board which was carried out large-scale location of Venus was on the Pioneer Venus Orbiter (1978), which carried out radar mapping of the surface. AMS Venus 15/16 (1978) have got on board the DBR with a resolution of 1-2 km, and Magellan (1989) had a DBR with a resolution of 100 m. During 1975-1982 Soviet leanders, being on a surface, have taken a number of panoramas with the high resolution of the order of shares of meter. Thus, there is a gap between the resolution of 100 m and shares of meter and it should be filled. Such experiment could be imaging from undercloud layer in a transparency window of 1 microns. Idea is not new, but technical study was not conducted.

AaEIN3 Mediates the Downregulation of Artemisinin Biosynthesis by Ethylene Signaling Through Promoting Leaf Senescence in Artemisia annua

PubMed Central

Tang, Yueli; Li, Ling; Yan, Tingxiang; Fu, Xueqing; Shi, Pu; Shen, Qian; Sun, Xiaofen; Tang, Kexuan

2018-01-01

Artemisinin is an important drug for malaria treatment, which is exclusively produced in Artemisia annua. It’s important to dissect the regulatory mechanism of artemisinin biosynthesis by diverse plant hormones and transcription factors. Our study shows ethylene, a plant hormone which accelerates flower and leaf senescence and fruit ripening, suppressed the expression of genes encoding three key enzymes ADS, DBR2, CYP71AV1, and a positive regulator AaORA involved in artemisinin biosynthesis. Then we isolated the gene encoding ETHYLENE-INSENSITIVE3 (EIN3), a key transcription factor in ethylene signaling pathway, by screening the transcriptome and genome database from Artemisia annua, named AaEIN3. Overexpressing AaEIN3 suppressed artemisinin biosynthesis, while repressing its expression with RNAi enhanced artemisinin biosynthesis in Artemisia annua, indicating AaEIN3 negatively regulates artemisinin biosynthesis. Further study showed the downregulation of artemisinin biosynthesis by ethylene required the mediation of AaEIN3. AaEIN3 could accelerate leaf senescence, and leaf senescence attenuated the expression of ADS, DBR2, CYP71AV1, and AaORA that are involved in artemisinin biosynthesis. Collectively, our study demonstrated a negative correlation between ethylene signaling and artemisinin biosynthesis, which is ascribed to AaEIN3-induced senescence process of leaves. Our work provided novel knowledge on the regulatory network of plant hormones for artemisinin metabolic pathway. PMID:29675029

Low threshold distributed Bragg reflector surface emitting laser diode with semiconductor air-bridge-supported top mirror

NASA Astrophysics Data System (ADS)

Hsin, W.; Du, G.; Gamelin, J. K.; Malloy, K. J.; Wang, S.

1990-03-01

A surface emitting laser diode (SELD) with two distributed Bragg reflectors (DBR) and semiconductor multilayer air-bridge-supported top mirror is fabricated. A low threshold current of 1.5 mA is achieved under room temperature CW operation. The spectrum shows a strong peak at 891 nm with a FWHM of 10 A. With light emission from the top Bragg reflector instead of from the back side of the substrate, laser arrays are easily formed with this novel structure.

Fabrication and characterization of the Si-photonics-integrated vertical resonant-cavity light-emitting diode

NASA Astrophysics Data System (ADS)

Kong, Duanhua; Kim, Taek; Kim, Sihan; Hong, Hyungi; Shcherbatko, Igor; Park, Youngsoo; Shin, Dongjae; Ha, Kyoung-Ho; Jeong, Gitae

2014-03-01

We designed and fabricated a 1.3-um hybrid vertical Resonant-Cavity Light-Emitting Diode for optical interconnect by using direct III-V wafer bonding on silicon on insulator (SOI). The device included InP based front distributed Bragg reflector (DBR), InGaAlAs based active layer, and SOI-based high-contrast-grating (HCG) as a back reflector. 42-uW continuous wave optical power was achieved at 20mA at room temperature.

Lateral electrochemical etching of III-nitride materials for microfabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jung

Conductivity-selective lateral etching of III-nitride materials is described. Methods and structures for making vertical cavity surface emitting lasers with distributed Bragg reflectors via electrochemical etching are described. Layer-selective, lateral electrochemical etching of multi-layer stacks is employed to form semiconductor/air DBR structures adjacent active multiple quantum well regions of the lasers. The electrochemical etching techniques are suitable for high-volume production of lasers and other III-nitride devices, such as lasers, HEMT transistors, power transistors, MEMs structures, and LEDs.

Crystal packing analysis of 1-(3,4-dimethoxyphenyl)-3-(4-bromophenyl)prop-2-en-1-one exhibiting a putative halogen bond Csbnd Br⋯O

NASA Astrophysics Data System (ADS)

Madan Kumar, Shankar; Fares Hezam, Al-Ostoot; Manjunath, B. C.; Shamprasad, Varija Raghu; Eissa Mohammed, Yasser Hussein; Mahesh, N.; Zabiulla; Shaukath, A. K.; Lokanath, N. K.; Byrappa, K.

2018-03-01

The title compound, 1-(3,4-dimethoxyphenyl)-3-(4-bromophenyl) prop-2-en-1-one (1DBr) was synthesized and characterized based on spectroscopic analysis (MS, FT-IR, Elemental analysis, UV-visible, 1H NMR and 13C NMR) and finally the three-dimensional structure is confirmed using single crystal X-ray diffraction studies. The molecule is almost planar and the C--H⋯O intramolecular hydrogen bond closes the ring S(5). In the crystal structure, the molecules are connected through intermolecular hydrogen bond C--H⋯O (R22(14) ring motif) and intermolecular interactions (C--H⋯π and C--O⋯π). Hirshfeld surfaces computational method was employed to quantify the inter-contacts (2D Fingerprint plots) and calculate enrichment ratio (E). The highest value of E is calculated for the contact Br⋯O (1.65) followed by C⋯C (1.02) and have high propensity for forming contacts in the crystal. This provides the basis for the existence of putative halogen bond of the type C-Br⋯O. In addition, the Energy-framework analysis was used to analyze and visualize the 3D-topology of the crystal packing. The dispersion energy framework is dominated over the electrostatic energy-frameworks. The thermogravimetric analysis (TGA) provided the thermal degradation of the 1DBr to be from 230 to 320 °C.

Assessment of tumor response to radiation and vascular targeting therapy in mice using quantitative ultrasound spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

El Kaffas, Ahmed; Sadeghi-Naini, Ali; Falou, Omar

Purpose: It is now recognized that the tumor vasculature is in part responsible for regulating tumor responses to radiation therapy. However, the extent to which radiation-based vascular damage contributes to tumor cell death remains unknown. In this work, quantitative ultrasound spectroscopy (QUS) methods were used to investigate the acute responses of tumors to radiation-based vascular treatments. Methods: Tumor xenografts (MDA-MB-231) were treated with single radiation doses of 2 or 8 Gy alone, or in combination with pharmacological agents that modulate vascular radiosensitivity. The midband fit, the slope, and the 0-MHz intercept QUS parameters were obtained from a linear-regression fit tomore » the averaged power spectrum of frequency-dependent ultrasound backscatter and were used to quantify acute tumor responses following treatment administration. Power spectrums were extracted from raw volumetric radio-frequency ultrasound data obtained before and 24 h following treatment administration. These parameters have previously been correlated to tumor cell death. Staining using in situ end labeling, carbonic anhydrase 9 and cluster of differentiation 31 of tumor sections were used to assess cell death, oxygenation, and vasculature distributions, respectively. Results: Results indicate a significant midband fit QUS parameter increases of 3.2 ± 0.3 dBr and 5.4 ± 0.5 dBr for tumors treated with 2 and 8 Gy radiation combined with the antiangiogenic agent Sunitinib, respectively. In contrast, tumors treated with radiation alone demonstrated a significant midband fit increase of 4.4 ± 0.3 dBr at 8 Gy only. Preadministration of basic fibroblast growth factor, an endothelial radioprotector, acted to minimize tumor response following single large doses of radiation. Immunohistochemical analysis was in general agreement with QUS findings; an R{sup 2} of 0.9 was observed when quantified cell death was correlated with changes in midband fit. Conclusions: Results from QUS analysis presented in this study confirm that acute tumor response is linked to a vascular effect following high doses of radiation therapy. Overall, this is in agreement with previous reports suggesting that acute tumor radiation response is regulated by a vascular-driven response. Data also suggest that Sunitinib may enhance tumor radiosensitivity through a vascular remodeling process, and that QUS may be sensitive to changes in tissue properties associated with vascular remodeling. Finally, the work also demonstrates the ability of QUS methods to monitor response to radiation-based vascular strategies.« less

Studies of Beam Expansion and Distributed Bragg Reflector Lasers for Fiber Optics and Optical Signal Processing.

DTIC Science & Technology

1981-03-03

described theory and experiments on the DBR laser and on the use of the Distributed Bragg Deflector ( DBD ) to act as a grating bean expander. The DBD is a...and telescope. 9 .\\pplications requiring more power can use the DBD as a power combiner for several laser stripes, as shown in Fig. 3. In design...Bragg deflector ( DBD ). This device consists of a corrugated waveguide, whose grating is slanted at an angle 6 with respect to the incident beam. The

Demonstration of a widely tunable digital supermode distributed Bragg reflector laser as a versatile source for near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Ciaffoni, L.; Hancock, G.; Hurst, P. L.; Kingston, M.; Langley, C. E.; Peverall, R.; Ritchie, G. A. D.; Whittaker, K. E.

2013-02-01

In this paper we report the characterization of a novel, widely tunable, diode laser source operating over the full telecom L-band (1563-1613 nm), namely the digital supermode distributed Bragg reflector (DS-DBR) laser, and its application to multi-wavelength gas sensing via absorption strategies. The spectroscopic performance of the laser has been assessed by investigating the ro-vibrational spectrum of CO2, and wavelength modulation spectroscopy was accomplished for proof-of-principle sensitive measurements in discrete spectral regions.

Reflective electroabsorption modular for compact base station radio-over-fiber systems

NASA Astrophysics Data System (ADS)

Wu, Yang; Chang, Wei-Xi; Yu, Paul K. L.

2003-07-01

A Radio-over-Fiber system with simplified Base Station (BS) is proposed in which a single chip DBR Reflective Electro-absorption Modulator (REAM) serves both as an optical transceiver and as a mixer at the BS. It enables full duplex optical transmission for base band and RF band services simultaneously due to good isolation between uplink and downlink at the same chip. Grating structure is incorporated into the EA modulator for the sake of system design. It also improves yield and efficiency of high-speed devices.

Fabrication and characterization of multi-stopband Fabry-Pérot filter array for nanospectrometers in the VIS range using SCIL nanoimprint technology

NASA Astrophysics Data System (ADS)

Shen, Yannan; Istock, André; Zaman, Anik; Woidt, Carsten; Hillmer, Hartmut

2018-05-01

Miniaturization of optical spectrometers can be achieved by Fabry-Pérot (FP) filter arrays. Each FP filter consists of two parallel highly reflecting mirrors and a resonance cavity in between. Originating from different individual cavity heights, each filter transmits a narrow spectral band (transmission line) with different wavelengths. Considering the fabrication efficiency, plasma enhanced chemical vapor deposition (PECVD) technology is applied to implement the high-optical-quality distributed Bragg reflectors (DBRs), while substrate conformal imprint lithography (one type of nanoimprint technology) is utilized to achieve the multiple cavities in just a single step. The FP filter array fabricated by nanoimprint combined with corresponding detector array builds a so-called "nanospectrometer". However, the silicon nitride and silicon dioxide stacks deposited by PECVD result in a limited stopband width of DBR (i.e., < 100 nm), which then limits the sensing range of filter arrays. However, an extension of the spectral range of filter arrays is desired and the topic of this investigation. In this work, multiple DBRs with different central wavelengths (λ c) are structured, deposited, and combined on a single substrate to enlarge the entire stopband. Cavity arrays are successfully aligned and imprinted over such terrace like surface in a single step. With this method, small chip size of filter arrays can be preserved, and the fabrication procedure of multiple resonance cavities is kept efficient as well. The detecting range of filter arrays is increased from roughly 50 nm with single DBR to 163 nm with three different DBRs.

Optical Control of Intersubband Absorption in a Multiple Quantum Well-Embedded Semiconductor Microcravity

NASA Technical Reports Server (NTRS)

Liu, Ansheng; Ning, Cun-Zheng

2000-01-01

Optical intersubband response of a multiple quantum well (MQW)-embedded microcavity driven by a coherent pump field is studied theoretically. The n-type doped MQW structure with three subbands in the conduction band is sandwiched between a semi-infinite medium and a distributed Bragg reflector (DBR). A strong pump field couples the two upper subbands and a weak field probes the two lower subbands. To describe the optical response of the MQW-embedded microcavity, we adopt a semi-classical nonlocal response theory. Taking into account the pump-probe interaction, we derive the probe-induced current density associated with intersubband transitions from the single-particle density-matrix formalism. By incorporating the current density into the Maxwell equation, we solve the probe local field exactly by means of Green's function technique and the transfer-matrix method. We obtain an exact expression for the probe absorption coefficient of the microcavity. For a GaAs/Al(sub x)Ga(sub 1-x)As MQW structure sandwiched between a GaAs/AlAs DBR and vacuum, we performed numerical calculations of the probe absorption spectra for different parameters such as pump intensity, pump detuning, and cavity length. We find that the probe spectrum is strongly dependent on these parameters. In particular, we find that the combination of the cavity effect and the Autler-Townes effect results in a triplet in the optical spectrum of the MQW system. The optical absorption peak value and its location can be feasibly controlled by varying the pump intensity and detuning.

Sub-wavelength grating structure on the planar waveguide (Conference Presentation)

NASA Astrophysics Data System (ADS)

Qing-Song, Zhu; Sheng-Hui, Chen

2016-10-01

Making progress in recent years, with the technology of the grating, the grating period can be reduced to shrink the size of the light coupler on a waveguide. The working wavelength of the light coupler can be in the range from the near-infrared to visible. In this study , we used E-gun evaporation system with ion-beam-assisted deposition system to fabricate bottom cladding (SiO2), guiding layer (Ta2O5) and Distributed Bragg Reflector(DBR) of the waveguide on the silicon substrate. Electron-beam lithography is used to make sub-wavelength gratings and reflector grating on the planar waveguide which is a coupling device on the guiding layer. The best fabrication parameters were analyzed to deposit the film. The exposure and development times also influenced to fabricate the grating quality. The purpose is to reduce the device size and enhance coupling efficiency which maintain normal incidence of the light . We designed and developed the device using the Finite-Difference Time-Domain (FDTD) method. The grating period, depth, fill factor, film thickness, Distributed Bragg Reflector(DBR) numbers and reflector grating period have been discussed to enhance coupling efficiency and maintained normal incidence of the light. According to the simulation results, when the wavelength is 1300 nm, the coupling grating period is 720 nm and the Ta2O5 film is 460 nm with 360 nm of reflector grating period and 2 layers of Distributed Bragg Reflector, which had the optimum coupling efficiency and normal incidence angle. In the measurement, We successfully measured the TE wave coupling efficiency of the photoresist grating coupling device.

Aligning Theory and Design: The Development of an Online Learning Intervention to Teach Evidence-based Practice for Maximal Reach.

PubMed

Delagran, Louise; Vihstadt, Corrie; Evans, Roni

2015-09-01

Online educational interventions to teach evidence-based practice (EBP) are a promising mechanism for overcoming some of the barriers to incorporating research into practice. However, attention must be paid to aligning strategies with adult learning theories to achieve optimal outcomes. We describe the development of a series of short self-study modules, each covering a small set of learning objectives. Our approach, informed by design-based research (DBR), involved 6 phases: analysis, design, design evaluation, redesign, development/implementation, and evaluation. Participants were faculty and students in 3 health programs at a complementary and integrative educational institution. We chose a reusable learning object approach that allowed us to apply 4 main learning theories: events of instruction, cognitive load, dual processing, and ARCS (attention, relevance, confidence, satisfaction). A formative design evaluation suggested that the identified theories and instructional approaches were likely to facilitate learning and motivation. Summative evaluation was based on a student survey (N=116) that addressed how these theories supported learning. Results suggest that, overall, the selected theories helped students learn. The DBR approach allowed us to evaluate the specific intervention and theories for general applicability. This process also helped us define and document the intervention at a level of detail that covers almost all the proposed Guideline for Reporting Evidence-based practice Educational intervention and Teaching (GREET) items. This thorough description will facilitate the interpretation of future research and implementation of the intervention. Our approach can also serve as a model for others considering online EBP intervention development.

Chirp-aided power fading mitigation for upstream 100 km full-range long reach PON with DBR DML

NASA Astrophysics Data System (ADS)

Zhang, Kuo; He, Hao; Xin, Haiyun; Hu, Weisheng; Liang, Song; Lu, Dan; Zhao, Lingjuan

2018-01-01

The DML is a promising option for cost-sensitive ONUs in optical access networks, but suffers from severe power fading due to dispersion and chirp. In this work, we investigate to mitigate the power fading by optimizing the chirp. Theoretical analysis indicates, a see-saw effect, influenced by the bias, exists between the adiabatic notch-induced fading (A-fading) and the transient notch-induced fading (T-fading). High bias can mitigate T-fading, but causes large A-fading. Low bias can avoid A-fading, but cannot completely mitigate T-fading. For each transmission distance, balance should be achieved to favor transmission. The ∼20 km short distance requires high bias to obtain large adiabatic chirp to counteract the T-fading, while the ∼100 km long distance requires relatively low bias to avoid the A-fading. With this power fading mitigation technique, we conduct upstream transmission experiment of LR-PON. Experiments show that, although signal contamination is inevitable, clear ;1; and ;0; are obtained with this power fading mitigation scheme for any 0 ∼100 km distance with 10 Gb/s OOK signal and DBR DML. The optical power budget penalty induced by 0 ∼100 km fiber is limited within only 2.2 dB, with optimum bias for each distance. More than 10 and 15 dB improvement is achieved when BER is 10-3 and 10-6. A method is also proposed to automatically obtain optimum bias from the ranging procedure of PON protocol.

Aligning Theory and Design: The Development of an Online Learning Intervention to Teach Evidence-based Practice for Maximal Reach

PubMed Central

Vihstadt, Corrie; Evans, Roni

2015-01-01

Background: Online educational interventions to teach evidence-based practice (EBP) are a promising mechanism for overcoming some of the barriers to incorporating research into practice. However, attention must be paid to aligning strategies with adult learning theories to achieve optimal outcomes. Methods: We describe the development of a series of short self-study modules, each covering a small set of learning objectives. Our approach, informed by design-based research (DBR), involved 6 phases: analysis, design, design evaluation, redesign, development/implementation, and evaluation. Participants were faculty and students in 3 health programs at a complementary and integrative educational institution. Results: We chose a reusable learning object approach that allowed us to apply 4 main learning theories: events of instruction, cognitive load, dual processing, and ARCS (attention, relevance, confidence, satisfaction). A formative design evaluation suggested that the identified theories and instructional approaches were likely to facilitate learning and motivation. Summative evaluation was based on a student survey (N=116) that addressed how these theories supported learning. Results suggest that, overall, the selected theories helped students learn. Conclusion: The DBR approach allowed us to evaluate the specific intervention and theories for general applicability. This process also helped us define and document the intervention at a level of detail that covers almost all the proposed Guideline for Reporting Evidence-based practice Educational intervention and Teaching (GREET) items. This thorough description will facilitate the interpretation of future research and implementation of the intervention. Our approach can also serve as a model for others considering online EBP intervention development. PMID:26421233

High-power, surface-emitting quantum cascade laser operating in a symmetric grating mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyle, C.; Sigler, C.; Kirch, J. D.

2016-03-21

Grating-coupled surface-emitting (GCSE) lasers generally operate with a double-lobed far-field beam pattern along the cavity-length direction, which is a result of lasing being favored in the antisymmetric grating mode. We experimentally demonstrate a GCSE quantum-cascade laser design allowing high-power, nearly single-lobed surface emission parallel to the longitudinal cavity. A 2nd-order Au-semiconductor distributed-feedback (DFB)/distributed-Bragg-reflector (DBR) grating is used for feedback and out-coupling. The DFB and DBR grating regions are 2.55 mm- and 1.28 mm-long, respectively, for a total grating length of 5.1 mm. The lasers are designed to operate in a symmetric (longitudinal) grating mode by causing resonant coupling of the guided optical modemore » to the antisymmetric surface-plasmon modes of the 2nd-order metal/semiconductor grating. Then, the antisymmetric modes are strongly absorbed by the metal in the grating, causing the symmetric mode to be favored to lase, which, in turn, produces a single-lobed beam over a range of grating duty-cycle values of 36%–41%. Simulations indicate that the symmetric mode is always favored to lase, independent of the random phase of reflections from the device's cleaved ends. Peak pulsed output powers of ∼0.4 W were measured with nearly single-lobe beam-pattern (in the longitudinal direction), single-spatial-mode operation near 4.75 μm wavelength. Far-field measurements confirm a diffraction-limited beam pattern, in agreement with simulations, for a source-to-detector separation of 2 m.« less

Realization of back-side heterogeneous hybrid III-V/Si DBR lasers for silicon photonics

NASA Astrophysics Data System (ADS)

Durel, Jocelyn; Ferrotti, Thomas; Chantre, Alain; Cremer, Sébastien; Harduin, Julie; Bernabé, Stéphane; Kopp, Christophe; Boeuf, Frédéric; Ben Bakir, Badhise; Broquin, Jean-Emmanuel

2016-02-01

In this paper, the simulation, design and fabrication of a back-side coupling (BSC) concept for silicon photonics, which targets heterogeneous hybrid III-V/Si laser integration is presented. Though various demonstrations of a complete SOI integration of passive and active photonic devices have been made, they all feature multi-level planar metal interconnects, and a lack of integrated light sources. This is mainly due to the conflict between the need of planar surfaces for III-V/Si bonding and multiple levels of metallization. The proposed BSC solution to this topographical problem consists in fabricating lasers on the back-side of the Si waveguides using a new process sequence. The devices are based on a hybrid structure composed of an InGaAsP MQW active area and a Si-based DBR cavity. The emitted light wavelength is accordable within a range of 20 nm around 1.31μm thanks to thermal heaters and the laser output is fiber coupled through a Grating Coupler (GC). From a manufacturing point of view, the BSC approach provides not only the advantages of allowing the use of a thin-BOX SOI instead of a thick one; but it also shifts the laser processing steps and their materials unfriendly to CMOS process to the far back-end areas of fabrication lines. Moreover, aside from solving technological integration issues, the BSC concept offers several new design opportunities for active and passive devices (heat sink, Bragg gratings, grating couplers enhanced with integrated metallic mirrors, tapers…). These building boxes are explored here theoretically and experimentally.

Defect-related degradation of III-V/Silicon 1.55 μm DBR laser diodes

NASA Astrophysics Data System (ADS)

Buffolo, Matteo; Meneghini, Matteo; De Santi, Carlo; Trivellin, Nicola; Davenport, Michael L.; Bowers, John E.; Meneghesso, Gaudenzio; Zanoni, Enrico

2018-02-01

This paper reports on an extensive investigation on the degradation mechanisms that may limit the long term reliability of heterogeneous III-V/Silicon DBR laser diodes for integrated telecommunication applications in the 1.55 μm window. The devices under test, aged for up to 500 hours under different bias conditions, showed a gradual variation of both optical (L-I) and electrical (I-V, C-V) characteristics. In particular, the laser diodes exhibited an increase in the threshold current, a decrease of the turn-on voltage and an increase in the apparent charge density within the space-charge region, which was extrapolated from C-V measurements. For longer stress times, these two latter processes were found to be well correlated with the worsening of the optical parameters, which suggests that degradation occurred due to an increase in the density of defects within the active region, with consequent decrease in the non-radiative (SRH) lifetime. This conclusion is also supported by the fact that during stress the apparent charge profiles indicated a re-distribution of charge within the junction. A preliminary investigation on the physical origin of the defects responsible for degradation was carried out by DLTS measurements, which revealed the presence of five different deep levels, with a main trap located around 0.43 eV above the valence band energy. This trap was found to be compatible with an interface defect located between the In0.53AlxGa0.47-xAs SCH region and the InP layer.

Passive cavity surface-emitting lasers: option of temperature-insensitive lasing wavelength for uncooled dense wavelength division multiplexing systems

NASA Astrophysics Data System (ADS)

Shchukin, V. A.; Ledentsov, N. N.; Slight, T.; Meredith, W.; Gordeev, N. Y.; Nadtochy, A. M.; Payusov, A. S.; Maximov, M. V.; Blokhin, S. A.; Blokhin, A. A.; Zadiranov, Yu. M.; Maleev, N. A.; Ustinov, V. M.; Choquette, K. D.

2016-03-01

A concept of passive cavity surface-emitting laser is proposed aimed to control the temperature shift of the lasing wavelength. The device contains an all-semiconductor bottom distributed Bragg reflector (DBR), in which the active medium is placed, a dielectric resonant cavity and a dielectric top DBR, wherein at least one of the dielectric materials has a negative temperature coefficient of the refractive index, dn/dT < 0. This is shown to be the case for commonly used dielectric systems SiO2/TiO2 and SiO2/Ta2O5. Two SiO2/TiO2 resonant structures having a cavity either of SiO2 or TiO2 were deposited on a substrate, their optical power reflectance spectra were measured at various temperatures, and refractive index temperature coefficients were extracted, dn/dT = 0.0021 K-1 for SiO2 and dn/dT = -0.0092 K-1 for TiO2. Using such dielectric materials allows designing passive cavity surface-emitting lasers having on purpose either positive, or zero, or negative temperature shift of the lasing wavelength dλ/dT. A design for temperature-insensitive lasing wavelength (dλ/dT = 0) is proposed. Employing devices with temperature-insensitive lasing wavelength in wavelength division multiplexing systems may allow significant reducing of the spectral separation between transmission channels and an increase in number of channels for a defined spectral interval enabling low cost energy efficient uncooled devices.

Genetic Screens in Yeast to Identify BRCA1 Modifiers

DTIC Science & Technology

2005-12-01

wall chitin COX13 YGL191W subunit of cytochrome c oxidase DBP5 YOR046C,RAT8 ATP-dependent RNA helicase DBP6 YNR038W ribosome biogenesis DBR1 YKL149C...DML1 YMR211W inv in mtDNA inheritance DPB11 YJL090C reqd for loading DNA polymerase,checkpt DUN1 YDL101C checkpt for DNA damage DIN7 structural ...for assembly of cytochrome c oxidase PFA4 YOL003C palmitoyltransferase activity PHD1 YKL043W enhances pseudohyphal growth,reg FLO11exp PPA2

Understanding temperature tuning of the all polymer co-extruded laser

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Andrews, Jim; Aviles, Michael; Dawson, Nathan; Petrus, Joshua; Mazzocco, Anthony; Singer, Ken; Baer, Eric; Song, Hyunmin

2012-10-01

We investigate the effects of elevated temperatures on a few types of all-polymer multilayer films that were fabricated using a co-extrusion melt-process technique. We report on the anisotropic thermal expansion of the multilayer films, which affects the photonic crystal structure via constituent wise induced anisotropic strains and a change in the relative refractive indices. In addition to the characterization of these films in the temperature range of approximately 20-95 degrees C, we show the application to non-contact temperature sensing and wavelength tuning of all polymer Distributed FeedBack (DFB) lasers and Distributed Bragg Reflector (DBR) lasers.

Resonant cavity light-emitting diodes based on dielectric passive cavity structures

NASA Astrophysics Data System (ADS)

Ledentsov, N.; Shchukin, V. A.; Kropp, J.-R.; Zschiedrich, L.; Schmidt, F.; Ledentsov, N. N.

2017-02-01

A novel design for high brightness planar technology light-emitting diodes (LEDs) and LED on-wafer arrays on absorbing substrates is proposed. The design integrates features of passive dielectric cavity deposited on top of an oxide- semiconductor distributed Bragg reflector (DBR), the p-n junction with a light emitting region is introduced into the top semiconductor λ/4 DBR period. A multilayer dielectric structure containing a cavity layer and dielectric DBRs is further processed by etching into a micrometer-scale pattern. An oxide-confined aperture is further amended for current and light confinement. We study the impact of the placement of the active region into the maximum or minimum of the optical field intensity and study an impact of the active region positioning on light extraction efficiency. We also study an etching profile composed of symmetric rings in the etched passive cavity over the light emitting area. The bottom semiconductor is an AlGaAs-AlAs multilayer DBR selectively oxidized with the conversion of the AlAs layers into AlOx to increase the stopband width preventing the light from entering the semiconductor substrate. The approach allows to achieve very high light extraction efficiency in a narrow vertical angle keeping the reasonable thermal and current conductivity properties. As an example, a micro-LED structure has been modeled with AlGaAs-AlAs or AlGaAs-AlOx DBRs and an active region based on InGaAlP quantum well(s) emitting in the orange spectral range at 610 nm. A passive dielectric SiO2 cavity is confined by dielectric Ta2O5/SiO2 and AlGaAs-AlOx DBRs. Cylindrically-symmetric structures with multiple ring patterns are modeled. It is demonstrated that the extraction coefficient of light to the air can be increased from 1.3% up to above 90% in a narrow vertical angle (full width at half maximum (FWHM) below 20°). For very small oxide-confined apertures 100nm the narrowing of the FWHM for light extraction can be reduced down to 5°. Consequently high efficiency high brightness arrays of micro-LEDs becomes possible. For single emitters the approach is particularly interesting for oscillator strength engineering allowing high speed data transmission and for single photonics applying single quantum dot (QD) emitters and allowing >90% coupling of the emission into single mode fiber. We also note that for longer wavelength ( 1300nm) QDs the thickness of the layers and surface patterns significantly increase allowing greatly reduced processing tolerances and applying further simplifications due to the possibility of using high contrast GaAs-AlOx DBRs.

Influence of an Interfacial Effect on the Laser Performance of a Rhodamine 6G/Cellulose Acetate Waveguide on a Vinylidene Fluoride Copolymer Layer.

PubMed

Tsutsumi, Naoto; Hirano, Yoshinori; Kinashi, Kenji; Sakai, Wataru

2018-06-12

The fluorescent properties of dyes and fluorophores in condensed matter significantly affect the laser performance of organic dye lasers and fluorescent polymer lasers. Concentration quenching of fluorescence is commonly observed in condensed matter. Several approaches have been presented to suppress such quenching, such as the use of a dendrimer and the use of effective energy transfer in a guest-host system. The enhanced fluorescence of rhodamine 6G (R6G) dye on a vinylidene fluoride polymer is an alternative method for enhancing laser performance because of the roughness of the P(VDF-TrFE) surface and the interaction between polar β-crystals of P(VDF-TrFE) and R6G dye. In this paper, a significant improvement in slope efficiency (SE) is demonstrated without a significant depression in the lasing threshold for distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers fabricated using an R6G-dispersed cellulose acetate (CA) matrix spin-coated onto a copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) thin film. SEs of 3.4 and 1.3% were measured for DBR and DFB laser devices with CA/R6G on a P(VDF-TrFE) thin film, respectively, whereas an SE of less than 1.0% was measured for both corresponding laser devices without a P(VDF-TrFE) thin film. From the aspect of simple fabrication procedures, repeatability in device fabrication and performance, stability of the device, time for device fabrication, the present approach is the most preferable way for industrial applications, requiring only the additional step of spin-coating of a P(VDF-TrFE) thin film.

Design for high-power, single-lobe, grating-surface-emitting quantum cascade lasers enabled by plasmon-enhanced absorption of antisymmetric modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sigler, C.; Kirch, J. D.; Mawst, L. J.

2014-03-31

Resonant coupling of the transverse-magnetic polarized (guided) optical mode of a quantum-cascade laser (QCL) to the antisymmetric surface-plasmon modes of 2nd-order distributed-feedback (DFB) metal/semiconductor gratings results in strong antisymmetric-mode absorption. In turn, lasing in the symmetric mode, that is, surface emission in a single-lobe far-field beam pattern, is strongly favored over controllable ranges in grating duty cycle and tooth height. By using core-region characteristics of a published 4.6 μm-emitting QCL, grating-coupled surface-emitting (SE) QCLs are analyzed and optimized for highly efficient single-lobe operation. For infinite-length devices, it is found that when the antisymmetric mode is resonantly absorbed, the symmetric mode hasmore » negligible absorption loss (∼0.1 cm{sup −1}) while still being efficiently outcoupled, through the substrate, by the DFB grating. For finite-length devices, 2nd-order distributed Bragg reflector (DBR) gratings are used on both sides of the DFB grating to prevent uncontrolled reflections from cleaved facets. Equations for the threshold-current density and the differential quantum efficiency of SE DFB/DBR QCLs are derived. For 7 mm-long, 8.0 μm-wide, 4.6 μm-emitting devices, with an Ag/InP grating of ∼39% duty cycle, and ∼0.22 μm tooth height, threshold currents as low as 0.45 A are projected. Based on experimentally obtained internal efficiency values from high-performance QCLs, slope efficiencies as high as 3.4 W/A are projected; thus, offering a solution for watt-range, single-lobe CW operation from SE, mid-infrared QCLs.« less

Wavelength stabilized high pulse power laser diodes for automotive LiDAR

NASA Astrophysics Data System (ADS)

Knigge, A.; Klehr, A.; Wenzel, H.; Zeghuzi, A.; Fricke, J.; Maaßdorf, A.; Liero, A.; Tränkle, G.

2018-03-01

Diode lasers generating optical pulses with high peak power and lengths in the nanosecond range are key components of systems for free-space communication, metrology, material processing, spectroscopy, and light detection and ranging (LiDAR) as needed for object detection and autonomous driving. Automotive LiDAR systems demand additionally a good beam quality and low wavelength shift with temperature due to the wide operating temperature span. We present here internally wavelength stabilized lasers emitting ns optical pulses from an emission aperture between 30 μm and 100 μm with peak powers of tens of Watts at wavelengths around 905 nm. The vertical structure based on AlGaAs (confinement and cladding layers) and InGaAs (active quantum well) is especially optimized for pulsed operation with respect to the implementation of a surface Bragg grating with a high reflectivity. The fabricated 6 mm long distributed Bragg reflector (DBR) broad area (BA) lasers are electrically driven by an in-house developed high-speed unit generating 3 to 10 ns long nearly rectangular shaped current pulses with amplitudes of up to 250 A. Such lasers emit optical pulses with a peak power of more than 30 W at 95 A pulse current up to a temperature of 85°C with a wavelength shift as low as 65 pm/K and a lateral beam propagation factor less than 10. The influence of the lateral aperture width and the pulse length on the beam quality will be shown. A monolithic integration of 3 DBR BA lasers on a single chip whose emission can be combined into a single beam raises the output power to more than 100 W.

Frequency locking of compact laser-diode modules at 633 nm

NASA Astrophysics Data System (ADS)

Nölleke, Christian; Leisching, Patrick; Blume, Gunnar; Jedrzejczyk, Daniel; Pohl, Johannes; Feise, David; Sahm, Alexander; Paschke, Katrin

2018-02-01

This work reports on a compact diode-laser module emitting at 633 nm. The emission frequency can be tuned with temperature and current, while optical feedback of an internal DBR grating ensures single-mode operation. The laser diode is integrated into a micro-fabricated package, which includes optics for beam shaping, a miniaturized optical isolator, and a vapor cell as frequency reference. The achieved absolute frequency stability is below 10-8 , while the output power can be more than 10 mW. This compact absolute frequency-stabilized laser system can replace gas lasers and may be integrated in future quantum technology devices.

[Oncologic, functional, and aesthetics results; evaluation of the quality of life after latissimus dorsi flap breast reconstruction. About a retrospective series of 450 patients].

PubMed

Dejode, M; Bordes, V; Jaffré, I; Classe, J-M; Dravet, F

2011-06-01

Retrospective assesssment from 1998 to 2005 from women who have a breast reconstruction by autologus latissimus flap or by latissimus flap and silicone breast implant for differed breast reconstruction (DBR) or mastectomy and immediate breast reconstruction (MIBR). Analysis of oncologic results on 450 patients. Analysis of aesthetic, functional results and of quality of life by an anonymous questionnaire in the non progressive patients (407): 263 appraisable answers (13 DBR, 127 MIBR). Middle age: 49.8 years. Forty-three patients (9.5%) had a relapse of their disease, 33 patients died (7.2%). The relapse of the disease was done in the form of metastasis alone: 29 (67.4%), metastasis and local recurrence: three (7%), local recurrence only: four (9.3%), not specified: seven (16.3%). The average time between the breast reconstruction and the relapse was 18.25±15.4 months. The overall assessment is of 7.68/10. There is no statistical difference between immediate reconstruction and delayed reconstruction. A total of 11.2% patients considered it to be bad (<5/10). The symmetry between the two breasts in time is of 6.6/10 and 19.9% patients considered it to be bad (<5/10). The scar ransom, considered to be most important, is mostly in the back (4.1/10) then on the controlateral breast and then the breast reconstruction. This ransom is not easily acceptable in 15 to 20% of the patients. The discomfort and the pain prevail above all in the back (3.56 and 2.59/10). Weaker symptoms in the event of immediate reconstruction than delayed reconstruction. We noted that 77.2% had kinesitherapy after surgery and 18.9% continues to have kinesitherapy, long time after surgery, mainly for massages of the back. The handicap is considered to be overall low 2.5/10 but 10% of the patients keep a feeling of important handicap (>7.5/10). Seventy-one of the patients are serene. The discomfort to wear a bathing suit or to look at bare-chested is low (2.59 and 2.44/10). However 8.9% are in a very discomfort to see themselves bare-chested and 17.6% to show themselves to their spouse, with an impact on their emotional and sexual life in 36.4% of the cases. There is no significant difference between MIBR and DBR but on the other hand according to the judgement of the woman of her aesthetic result. A total of 95.7% do not regret having made this breast reconstruction. This study makes it possible to concentrate on the group of non satisfied patient for better determining the causes and the improvements of the surgical techniques to bring but also the overall surgical management of the patient even if most of the patients were mainly satisfied with their breast reconstruction. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Development of Fiber-Based Laser Systems for LISA

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2010-01-01

We present efforts on fiber-based laser systems for the LISA mission at the NASA Goddard Space Flight Center. A fiber-based system has the advantage of higher robustness against external disturbances and easier implementation of redundancies. For a master oscillator, we are developing a ring fiber laser and evaluating two commercial products, a DBR linear fiber laser and a planar-waveguide external cavity diode laser. They all have comparable performance to a traditional NPRO at LISA band. We are also performing reliability tests of a 2-W Yb fiber amplifier and radiation tests of fiber laser/amplifier components. We describe our progress to date and discuss the path to a working LISA laser system design.

Compact diode laser module at 1116 nm with an integrated optical isolation and a PM-SMF output

NASA Astrophysics Data System (ADS)

Jedrzejczyk, Daniel; Hofmann, Julian; Werner, Nils; Sahm, Alexander; Paschke, Katrin

2017-02-01

In this work, a fiber-coupled diode laser module emitting around 1116 nm with an output power P < 60 mW is realized. As a laser light source a distributed Bragg reflector (DBR) ridge waveguide diode laser is applied. The module comprises temperature stabilizing components, a micro-lens system as well as an optical micro-isolator. At the output, a polarization-maintaining single-mode fiber (PM-SMF) with a core diameter of 5.5 μm and a standard FC/APC connector are utilized. The generated diffraction limited beam is characterized by a narrow linewidth ( δν < 10 MHz) and a high polarization extinction ratio (PER > 25 dB).

DBR, Sub-wavelength grating, and Photonic crystal slab Fabry-Perot cavity design using phase analysis by FDTD.

PubMed

Kim, Jae Hwan Eric; Chrostowski, Lukas; Bisaillon, Eric; Plant, David V

2007-08-06

We demonstrate a Finite-Difference Time-Domain (FDTD) phase methodology to estimate resonant wavelengths in Fabry-Perot (FP) cavity structures. We validate the phase method in a conventional Vertical-Cavity Surface-Emitting Laser (VCSEL) structure using a transfer-matrix method, and compare results with a FDTD reflectance method. We extend this approach to a Sub-Wavelength Grating (SWG) and a Photonic Crystal (Phc) slab, either of which may replace one of the Distributed Bragg Reflectors (DBRs) in the VCSEL, and predict resonant conditions with varying lithographic parameters. Finally, we compare the resonant tunabilities of three different VCSEL structures, taking quality factors into account.

Life-cycle assessment of transportation biofuels from hydrothermal liquefaction of forest residues in British Columbia.

PubMed

Nie, Yuhao; Bi, Xiaotao

2018-01-01

Biofuels from hydrothermal liquefaction (HTL) of abundantly available forest residues in British Columbia (BC) can potentially make great contributions to reduce the greenhouse gas (GHG) emissions from the transportation sector. A life-cycle assessment was conducted to quantify the GHG emissions of a hypothetic 100 million liters per year HTL biofuel system in the Coast Region of BC. Three scenarios were defined and investigated, namely, supply of bulky forest residues for conversion in a central integrated refinery (Fr-CIR), HTL of forest residues to bio-oil in distributed biorefineries and subsequent upgrading in a central oil refinery (Bo-DBR), and densification of forest residues in distributed pellet plants and conversion in a central integrated refinery (Wp-CIR). The life-cycle GHG emissions of HTL biofuels is 20.5, 17.0, and 19.5 g CO 2 -eq/MJ for Fr-CIR, Bo-DBR, and Wp-CIR scenarios, respectively, corresponding to 78-82% reduction compared with petroleum fuels. The conversion stage dominates the total GHG emissions, making up more than 50%. The process emitting most GHGs over the life cycle of HTL biofuels is HTL buffer production. Transportation emission, accounting for 25% of Fr-CIR, can be lowered by 83% if forest residues are converted to bio-oil before transportation. When the credit from biochar applied for soil amendment is considered, a further reduction of 6.8 g CO 2 -eq/MJ can be achieved. Converting forest residues to bio-oil and wood pellets before transportation can significantly lower the transportation emission and contribute to a considerable reduction of the life-cycle GHG emissions. Process performance parameters (e.g., HTL energy requirement and biofuel yield) and the location specific parameter (e.g., electricity mix) have significant influence on the GHG emissions of HTL biofuels. Besides, the recycling of the HTL buffer needs to be investigated to further improve the environmental performance of HTL biofuels.

Protocol for the BRECAR study: a prospective cohort follow-up on the impact of breast reconstruction timing on health-related quality of life in women with breast cancer

PubMed Central

Herrera de la Muela, Maria; García López, Enrique; Frías Aldeguer, Laura; Gómez-Campelo, Paloma

2017-01-01

Introduction The completion of postmastectomy breast reconstruction (BR) in women with breast cancer can last from months to years, and to our knowledge, there is a lack of studies that analyse how the different types and times of reconstruction impact on the patient’s quality of life and psychosocial adjustment. The primary aim of the BREast Cancer Reconstruction (BRECAR Study) is twofold. First, to describe health-related quality of life (HRQoL), overall satisfaction with surgery and psychological impact (body image, self-esteem, depression and anxiety) on women who will have undergone a mastectomy with planned BR, considering the varied timing of BR procedures (immediate BR (iBR), delayed BR (dBR) and two-stage BR (2sBR)). To measure the impact on surgical outcomes, we will obtain data prior to and after surgery (6–9 and at 18 months of follow-up). Second, to analyse sociodemographic, clinical and psychosocial factors associated with HRQoL, satisfaction with surgery and psychological impact. Methods and analysis A prospective, observational, clinical cohort study of women diagnosed with breast cancer who have an indication for mastectomy treated at La Paz University Hospital (Madrid, Spain). Patients will be classified into one of three groups under conditions of routine clinical practice, based on the type of BR planned: the iBR group, the dBR group and the 2sBR group. Under typical clinical practice conditions, we will perform three visits: baseline visit (presurgery), V1 (6–9 months after diagnosis) and V2 (18 months after diagnosis). A sample size of 210 patients is estimated. Ethics and dissemination The study protocol and informed consent form have been reviewed and approved by the Institutional Review Board of La Paz Hospital (no. PI-2036). Dissemination of results will be via journal articles and conference presentations. PMID:29259059

Low-frequency quantitative ultrasound imaging of cell death in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadeghi-Naini, Ali; Falou, Omar; Czarnota, Gregory J.

Purpose: Currently, no clinical imaging modality is used routinely to assess tumor response to cancer therapies within hours to days of the delivery of treatment. Here, the authors demonstrate the efficacy of ultrasound at a clinically relevant frequency to quantitatively detect changes in tumors in response to cancer therapies using preclinical mouse models.Methods: Conventional low-frequency and corresponding high-frequency ultrasound (ranging from 4 to 28 MHz) were used along with quantitative spectroscopic and signal envelope statistical analyses on data obtained from xenograft tumors treated with chemotherapy, x-ray radiation, as well as a novel vascular targeting microbubble therapy.Results: Ultrasound-based spectroscopic biomarkers indicatedmore » significant changes in cell-death associated parameters in responsive tumors. Specifically changes in the midband fit, spectral slope, and 0-MHz intercept biomarkers were investigated for different types of treatment and demonstrated cell-death related changes. The midband fit and 0-MHz intercept biomarker derived from low-frequency data demonstrated increases ranging approximately from 0 to 6 dBr and 0 to 8 dBr, respectively, depending on treatments administrated. These data paralleled results observed for high-frequency ultrasound data. Statistical analysis of ultrasound signal envelope was performed as an alternative method to obtain histogram-based biomarkers and provided confirmatory results. Histological analysis of tumor specimens indicated up to 61% cell death present in the tumors depending on treatments administered, consistent with quantitative ultrasound findings indicating cell death. Ultrasound-based spectroscopic biomarkers demonstrated a good correlation with histological morphological findings indicative of cell death (r{sup 2}= 0.71, 0.82; p < 0.001).Conclusions: In summary, the results provide preclinical evidence, for the first time, that quantitative ultrasound used at a clinically relevant frequency, in addition to high-frequency ultrasound, can detect tissue changes associated with cell death in vivo in response to cancer treatments.« less

Utilizing the National Research Council's (NRC) Conceptual Framework for the Next Generation Science Standards (NGSS): A Self-Study in My Science, Engineering, and Mathematics Classroom

NASA Astrophysics Data System (ADS)

Corvo, Arthur Francis

Given the reality that active and competitive participation in the 21 st century requires American students to deepen their scientific and mathematical knowledge base, the National Research Council (NRC) proposed a new conceptual framework for K--12 science education. The framework consists of an integration of what the NRC report refers to as the three dimensions: scientific and engineering practices, crosscutting concepts, and core ideas in four disciplinary areas (physical, life and earth/spaces sciences, and engineering/technology). The Next Generation Science Standards (NGSS ), which are derived from this new framework, were released in April 2013 and have implications on teacher learning and development in Science, Technology, Engineering, and Mathematics (STEM). Given the NGSS's recent introduction, there is little research on how teachers can prepare for its release. To meet this research need, I implemented a self-study aimed at examining my teaching practices and classroom outcomes through the lens of the NRC's conceptual framework and the NGSS. The self-study employed design-based research (DBR) methods to investigate what happened in my secondary classroom when I designed, enacted, and reflected on units of study for my science, engineering, and mathematics classes. I utilized various best practices including Learning for Use (LfU) and Understanding by Design (UbD) models for instructional design, talk moves as a tool for promoting discourse, and modeling instruction for these designed units of study. The DBR strategy was chosen to promote reflective cycles, which are consistent with and in support of the self-study framework. A multiple case, mixed-methods approach was used for data collection and analysis. The findings in the study are reported by study phase in terms of unit planning, unit enactment, and unit reflection. The findings have implications for science teaching, teacher professional development, and teacher education.

Generation of spectrally-stable continuous-wave emission and ns pulses at 800 nm and 975 nm with a peak power of 4 W using a distributed Bragg reflector laser and a ridge-waveguide power amplifier

NASA Astrophysics Data System (ADS)

Klehr, A.; Wenzel, H.; Fricke, J.; Bugge, F.; Liero, A.; Hoffmann, Th.; Erbert, G.; Tränkle, G.

2015-03-01

Semiconductor based sources which emit high-power spectrally stable nearly diffraction-limited optical pulses in the nanosecond range are ideally suited for a lot of applications, such as free-space communications, metrology, material processing, seed lasers for fiber or solid state lasers, spectroscopy, LIDAR and frequency doubling. Detailed experimental investigations of 975 nm and 800 nm diode lasers based on master oscillator power amplifier (MOPA) light sources are presented. The MOPA systems consist of distributed Bragg reflector lasers (DBR) as master oscillators driven by a constant current and ridge waveguide power amplifiers which can be driven DC and by current pulses. In pulse regime the amplifiers modulated with rectangular current pulses of about 5 ns width and a repetition frequency of 200 kHz act as optical gates, converting the continuous wave (CW) input beam emitted by the DBR lasers into a train of short optical pulses which are amplified. With these experimental MOPA arrangements no relaxation oscillations in the pulse power occur. With a seed power of about 5 mW at a wavelength of 973 nm output powers behind the amplifier of about 1 W under DC injection and 4 W under pulsed operation, corresponding to amplification factors of 200 (amplifier gain 23 dB) and 800 (gain 29 dB) respectively, are reached. At 800 nm a CW power of 1 W is obtained for a seed power of 40 mW. The optical spectra of the emission of the amplifiers exhibit a single peak at a constant wavelength with a line width < 10 pm in the whole investigated current ranges. The ratios between laser and ASE levels were > 50 dB. The output beams are nearly diffraction limited with beam propagation ratios M2lat ~ 1.1 and M2ver ~ 1.2 up to 4 W pulse power.

NMR studies of double proton transfer in hydrogen bonded cyclic N,N'-diarylformamidine dimers: conformational control, kinetic HH/HD/DD isotope effects and tunneling.

PubMed

Lopez, Juan Miguel; Männle, Ferdinand; Wawer, Iwona; Buntkowsky, Gerd; Limbach, Hans-Heinrich

2007-08-28

Using dynamic NMR spectroscopy, the kinetics of the degenerate double proton transfer in cyclic dimers of polycrystalline (15)N,(15)N'-di-(4-bromophenyl)-formamidine (DBrFA) have been studied including the kinetic HH/HD/DD isotope effects in a wide temperature range. This transfer is controlled by intermolecular interactions, which in turn are controlled by the molecular conformation and hence the molecular structure. At low temperatures, rate constants were determined by line shape analysis of (15)N NMR spectra obtained using cross-polarization (CP) and magic angle spinning (MAS). At higher temperatures, in the microsecond time scale, rate constants and kinetic isotope effects were obtained by a combination of longitudinal (15)N and (2)H relaxation measurements. (15)N CPMAS line shape analysis was also employed to study the non-degenerate double proton transfer of polycrystalline (15)N,(15)N'-diphenyl-formamidine (DPFA). The kinetic results are in excellent agreement with the kinetics of DPFA and (15)N,(15)N'-di-(4-fluorophenyl)-formamidine (DFFA) studied previously for solutions in tetrahydrofuran. Two large HH/HD and HD/DD isotope effects are observed in the whole temperature range which indicates a concerted double proton transfer mechanism in the domain of the reaction energy surface. The Arrhenius curves are non-linear indicating a tunneling mechanism. Arrhenius curve simulations were performed using the Bell-Limbach tunneling model. The role of the phenyl group conformation and hydrogen bond compression on the barrier of the proton transfer is discussed.

Distributed feedback laser diode integrated with distributed Bragg reflector for continuous-wave terahertz generation.

PubMed

Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Ko, Hyunsung; Park, Jeong-Woo; Lee, Donghun; Jeon, Min Yong; Park, Kyung Hyun

2012-07-30

A widely tunable dual mode laser diode with a single cavity structure is demonstrated. This novel device consists of a distributed feedback (DFB) laser diode and distributed Bragg reflector (DBR). Micro-heaters are integrated on the top of each section for continuous and independent wavelength tuning of each mode. By using a single gain medium in the DFB section, an effective common optical cavity and common modes are realized. The laser diode shows a wide tunability of the optical beat frequency, from 0.48 THz to over 2.36 THz. Continuous wave THz radiation is also successfully generated with low-temperature grown InGaAs photomixers from 0.48 GHz to 1.5 THz.

Application of a broadly tunable SG-DBR QCL for multi-species trace gas spectroscopy.

PubMed

Diba, Abdou S; Xie, Feng; Gross, Barry; Hughes, Lawrence C; Zah, Chung-en; Moshary, Fred

2015-10-19

Feasibility of using a mid-Infrared tunable sampled-grating distributed Bragg reflectors quantum cascade laser for high resolution multicomponent trace gas spectroscopy is demonstrated. By controlling the driving currents to the front and back sections of the laser, we were able to tune a pulsed 4.55 µm laser over a frequency range a of 30 cm(-1) with high resolution, accuracy and repeatability. The laser was applied to absorption spectroscopy of ambient and reduced pressure (150 Torr) air in a 205 meters multi-pass Herriott cell, and by using standard LSQ fitting to a spectral database of these trace gases (HITRAN), the concentrations of nitrous oxide, carbon monoxide, and water vapor were retrieved.

Distributed bragg reflector using AIGaN/GaN

DOEpatents

Waldrip, Karen E.; Lee, Stephen R.; Han, Jung

2004-08-10

A supported distributed Bragg reflector or superlattice structure formed from a substrate, a nucleation layer deposited on the substrate, and an interlayer deposited on the nucleation layer, followed by deposition of (Al,Ga,B)N layers or multiple pairs of (Al,Ga,B)N/(Al,Ga,B)N layers, where the interlayer is a material selected from AlN, Al.sub.x Ga.sub.1-x N, and AlBN with a thickness of approximately 20 to 1000 angstroms. The interlayer functions to reduce or eliminate the initial tensile growth stress, thereby reducing cracking in the structure. Multiple interlayers utilized in an AlGaN/GaN DBR structure can eliminate cracking and produce a structure with a reflectivity value greater than 0.99.

JSEP fellowship

NASA Astrophysics Data System (ADS)

Goodman, Alvin M.; Powers, Edward J.

1993-06-01

In this dissertation, the precision of molecular-beam epitaxy (MBE) is taken advantage of in order to grow semiconductor reflectors, microcavities, and quantum wells for studies of vertical-cavity surface-emitting lasers (VCSEL's) and the coupling between reflectors and the spatially localized dipoles of semiconductor quantum wells. The design of the structures and the choice of epitaxial growth parameters used for the structures are discussed in detail. Experimental techniques and results are discussed which relate to studies that advance the optoelectronics technology and our understanding of fundamental physics. MBE is used to grow epitaxial structures in which a QW is precisely placed either in close proximity to a DBR, or near the surface of the epitaxial layer, so that a highly reflective mirror can be placed in close proximity to the QW.

Prosthetic breast reconstruction: indications and update

PubMed Central

Quinn, Tam T.; Miller, George S.; Rostek, Marie; Cabalag, Miguel S.; Rozen, Warren M.

2016-01-01

Background Despite 82% of patients reporting psychosocial improvement following breast reconstruction, only 33% patients choose to undergo surgery. Implant reconstruction outnumbers autologous reconstruction in many centres. Methods A systematic review of the literature was undertaken. Inclusion required: (I) Meta-analyses or review articles; (II) adult patients aged 18 years or over undergoing alloplastic breast reconstruction; (III) studies including outcome measures; (IV) case series with more than 10 patients; (V) English language; and (VI) publication after 1st January, 2000. Results After full text review, analysis and data extraction was conducted for a total of 63 articles. Definitive reconstruction with an implant can be immediate or delayed. Older patients have similar or even lower complication rates to younger patients. Complications include capsular contracture, hematoma and infection. Obesity, smoking, large breasts, diabetes and higher grade tumors are associated with increased risk of wound problems and reconstructive failure. Silicone implant patients have higher capsular contracture rates but have higher physical and psychosocial function. There were no associations made between silicone implants and cancer or systemic disease. There were no differences in outcomes or complications between round and shaped implants. Textured implants have a lower risk of capsular contracture than smooth implants. Smooth implants are more likely to be displaced as well as having higher rates of infection. Immediate breast reconstruction (IBR) gives the best aesthetic outcome if radiotherapy is not required but has a higher rate of capsular contracture and implant failure. Delayed-immediate reconstruction patients can achieve similar aesthetic results to IBR whilst preserving the breast skin if radiotherapy is required. Delayed breast reconstruction (DBR) patients have fewer complications than IBR patients. Conclusions Implant reconstruction is a safe and popular mode of post-mastectomy reconstruction. Evidence exists for the settings in which complications are more likely, and we can now more reliably predict outcomes of reconstruction on an individual basis and assess patient suitability. PMID:27047785

Light trapping in thin film solar cells using photonic engineering device concepts

NASA Astrophysics Data System (ADS)

Mutitu, James Gichuhi

In this era of uncertainty concerning future energy solutions, strong reservations have arisen over the continued use and pursuit of fossil fuels and other conventional sources of energy. Moreover, there is currently a strong and global push for the implementation of stringent measures, in order to reduce the amount of green house gases emitted by every nation. As a consequence, there has emerged a sudden and frantic rush for new renewable energy solutions. In this world of renewable energy technologies is where we find photovoltaic (PV) technology today. However, as is, there are still many issues that need to be addressed before solar energy technologies become economically viable and available to all people, in every part of the world. This renewed interest in the development of solar electricity, has led to the advancement of new avenues that address the issues of cost and efficiency associated with PV. To this end, one of the prominent approaches being explored is thin film solar cell (TFSC) technology, which offers prospects of lower material costs and enables larger units of manufacture than conventional wafer based technology. However, TFSC technologies suffer from one major problem; they have lower efficiencies than conventional wafer based solar cell technologies. This lesser efficiency is based on a number of reasons, one of which is that with less material, there is less volume for the absorption of incident photons. This shortcoming leads to the need for optical light trapping; which is concerned with admitting the maximum amount of light into the solar cell and keeping the light within the structure for as long as possible. In this thesis, I present the fundamental scientific ideas, practice and methodology behind the application of photonic engineering device concepts to increase the light trapping capacity of thin film solar cells. In the introductory chapters, I develop the basic ideas behind light trapping in a sequential manner, where the effects of the inclusion of various structures on the front and back surfaces of solar cells are examined. This framework is then adapted as a basis for the development of more advanced topics, such as the inclusion of micro and nano scale surface textures, diffraction gratings and photonic bandgap structures. Analyses of the effects of these light trapping structures is undertaken using performance metrics, such as the short circuit current characteristics and a band-edge enhancement factor, which all serve to quantitatively demonstrate the effects of the optical enhancements. I begin this thesis with an investigation of one dimensional photonic crystals, which are used as selective light filters between vertically stacked tandem multi-junction solar cells. These ideas are then further developed for single junction stand alone thin film solar cells, where the optical enhancement is shown to be very significant. A further investigation on the application of engineered photonic crystal materials as angular selective light filters is then presented; these filters are shown to overcome the physical limitations of light trapping that are imposed by the optical properties of materials; specifically limitations associated with total internal reflection. In the next part of this thesis, I present a fundamental redesign approach to multiple period distributed Bragg reflectors (DBR's) and their applications to solar cell light trapping. As it turns out, multiple period DBR's, which are required for high back surface reflectance - which is especially necessary in thin film solar cells - present formidable challenges in terms of cost and complexity when considered for high volume manufacturing. To this end, I show that when a single period DBR is combined with a phase matching and metallic layer, the combined structure can achieve high back surface reflectance that is comparable to that of a DBR structure with many more layers. This new structure reduces the back reflector complexity and is hence, amenable to large scale fabrication processes. In the latter sections of this thesis, I present a host of fabrication techniques that are used to realize micro and nano scale light trapping features. These techniques range from standard silicon wet etching processes, to customized and elaborate deep ultra-violet lithography, which is combined with inductively coupled plasma etching and used in order to realize sub-micron diffraction gratings. These textures are then applied to substrates on which thin film amorphous silicon solar cell structures are deposited, subsequent analyses on the effectiveness of these texturing processes is performed. Finally, this thesis concludes with the presentation of a blueprint for future explorations and applications of the developed light trapping techniques, to other thin film solar cell materials and technologies.

Anisotropic multi-spot DBR porous silicon chip for the detection of human immunoglobin G.

PubMed

Cho, Bomin; Um, Sungyong; Sohn, Honglae

2014-07-01

Asymmetric porous silicon multilayer (APSM)-based optical biosensor was developed to specify human Immunoglobin G (Ig G). APSM chip was generated by an electrochemical etching of silicon wafer using an asymmetric electrode configuration in aqueous ethanolic HF solution and constituted with nine arrayed porous silicon multilayer. APSM prepared from anisotropic etching conditions displayed a sharp reflection resonance in the reflectivity spectrum. Each spot displayed single reflection resonance at different wavelengths as a function of the lateral distance from the Pt counter electrode. The sensor system was consisted of the 3 x 3 spot array of APSM modified with protein A. The system was probed with an aqueous human Ig G. Molecular binding and specificity was monitored as a shift in wavelength of reflection resonance.

Enhanced photoresponse of monolayer molybdenum disulfide (MoS2) based on microcavity structure

NASA Astrophysics Data System (ADS)

Lu, Yanan; Yang, Guofeng; Wang, Fuxue; Lu, Naiyan

2018-05-01

There is an increasing interest in using monolayer molybdenum disulfide (MoS2) for optoelectronic devices because of its inherent direct band gap characteristics. However, the weak absorption of monolayer MoS2 restricts its applications, novel concepts need to be developed to address the weakness. In this work, monolayer MoS2 monolithically integrates with plane microcavity structure, which is formed by the top and bottom chirped distributed Bragg reflector (DBR), is demonstrated to improve the absorption of MoS2. The optical absorption is 17-fold enhanced, reaching values over 70% at work wavelength. Moreover, the monolayer MoS2-based photodetector device with microcavity presents a significantly increased photoresponse, demonstrating its promising prospects in MoS2-based optoelectronic devices.

Fabrication of novel structures to enhance the performance of microwave, millimeter wave and optical radiators

NASA Astrophysics Data System (ADS)

Gbele, Kokou

This dissertation has three parts which are distinctive from the perspective of their frequency regime of operation and from the nature of their contributions to the science and engineering communities. The first part describes work that was conducted on a vertical-external-cavity surface emitting-laser (VECSEL) in the optical frequency regime. We designed, fabricated, and tested a hybrid distributed Bragg reflector (DBR) mirror for a VECSEL sub-cavity operating at the laser emission wavelength of 1057 nm. The DBR mirror was terminated with a highly reflecting gold surface and integrated with an engineered pattern of titanium. This hybrid mirror achieved a reduction in half of the number of DBR layer pairs in comparison to a previously reported, successful VECSEL chip. Moreover, the output power of our VECSEL chip was measured to be beyond 4.0Wwith an optical-to-optical efficiency of 19.4%. Excellent power output stability was demonstrated; a steady 1.0 W output at 15.0 W pump power was measured for over an hour. The second part reports on an ultrafast in situ pump-probing of the nonequlibrium dynamics of the gain medium of a VECSEL under mode-locked conditions. We proposed and successfully tested a novel approach to measure the response of the inverted carriers in the active region of a VECSEL device while it was operating under passively mode-locked conditions. We employed the dual-frequency-comb spectroscopy (DFCS) technique using an asynchronous optical sampling (ASOPS) method based on modified time-domain spectroscopy (TDS) to measure the nonequilibrium dynamics of the gain medium of a phase-locked VECSEL that we designed and fabricated to operate at the 1030 nm emission wavelength. Our spectroscopic studies used a probe pulse of 100 fs and an in situ pump pulse of 13 ps. We probed the gain medium of the VECSEL and recorded a depletion time of 13 ps, a fast recovery period of 17 ps, and 110 ps for the slow recovery time. Our scans thus demonstrated a 140 ps full depletion-recovery cycle in the nonequilibrium state. The third part discusses work in the microwave and millimeter wave frequency regimes. A new method to fabricate Luneburg lenses was proposed and demonstrated. This type of lens is well known; it is versatile and has been used for many applications, including high power radars, satellite communications, and remote sensing systems. Because the fabrication of such a lens requires intricate and time consuming processes, we demonstrated the design, fabrication and testing of a Luneburg lens prototype using a 3-D printing rapid prototyping technique both at the X and Ka-V frequency bands. The measured results were in very good agreement with their simulated values. The fabricated X-band lens had a 12 cm diameter and produced a beam having a maximum gain of 20 dB and a beam directivity (half-power beam width (HPBW)) ranging from 12° to 19°). The corresponding Ka-V band lens had a 7 cm diameter; it produced a beam with a HPBW about the same as the X-band lens, but with a maximum gain of more than 20 dB.

Modal Analysis of β -Ga2O3:Cr Widely Tunable Luminescent Optical Microcavities

NASA Astrophysics Data System (ADS)

Alonso-Orts, M.; Nogales, E.; San Juan, J. M.; Nó, M. L.; Piqueras, J.; Méndez, B.

2018-06-01

Optical microcavities are key elements in many photonic devices, and those based on distributed Bragg reflectors (DBRs) enhance dramatically the end reflectivity, allowing for higher quality factors and finesse values. Besides, they allow for wide wavelength tunability, needed for nano- and microscale light sources to be used as photonic building blocks in the micro- and nanoscale. Understanding the complete behavior of light within the cavity is essential to obtaining an optimized design of properties and optical tunability. In this work, focused ion-beam fabrication of high refractive-index contrast DBR-based optical cavities within Ga2O3:Cr microwires grown and doped by the vapor-solid mechanism is reported. Room-temperature microphotoluminescence spectra show strong modulations from about 650 nm up to beyond 800 nm due to the microcavity resonance modes. Selectivity of the peak wavelength is achieved for two different cavities, demonstrating the tunability of this kind of optical system. Analysis of the confined modes is carried out by an analytical approximation and by finite-difference-time-domain simulations. A good agreement is obtained between the reflectivity values of the DBRs calculated from the experimental resonance spectra, and those obtained by finite-difference-time-domain simulations. Experimental reflectivities up to 70% are observed in the studied wavelength range and cavities, and simulations demonstrate that reflectivities up to about 90% could be reached. Therefore, Ga2O3:Cr high-reflectivity optical microcavities are shown as good candidates for single-material-based, widely tunable light emitters for micro- and nanodevices.

Protocol for the BRECAR study: a prospective cohort follow-up on the impact of breast reconstruction timing on health-related quality of life in women with breast cancer.

PubMed

Herrera de la Muela, Maria; García López, Enrique; Frías Aldeguer, Laura; Gómez-Campelo, Paloma

2017-12-19

The completion of postmastectomy breast reconstruction (BR) in women with breast cancer can last from months to years, and to our knowledge, there is a lack of studies that analyse how the different types and times of reconstruction impact on the patient's quality of life and psychosocial adjustment.The primary aim of the BREast Cancer Reconstruction (BRECAR Study) is twofold. First, to describe health-related quality of life (HRQoL), overall satisfaction with surgery and psychological impact (body image, self-esteem, depression and anxiety) on women who will have undergone a mastectomy with planned BR, considering the varied timing of BR procedures (immediate BR (iBR), delayed BR (dBR) and two-stage BR (2sBR)). To measure the impact on surgical outcomes, we will obtain data prior to and after surgery (6-9 and at 18 months of follow-up). Second, to analyse sociodemographic, clinical and psychosocial factors associated with HRQoL, satisfaction with surgery and psychological impact. A prospective, observational, clinical cohort study of women diagnosed with breast cancer who have an indication for mastectomy treated at La Paz University Hospital (Madrid, Spain).Patients will be classified into one of three groups under conditions of routine clinical practice, based on the type of BR planned: the iBR group, the dBR group and the 2sBR group.Under typical clinical practice conditions, we will perform three visits: baseline visit (presurgery), V1 (6-9 months after diagnosis) and V2 (18 months after diagnosis). A sample size of 210 patients is estimated. The study protocol and informed consent form have been reviewed and approved by the Institutional Review Board of La Paz Hospital (no. PI-2036). Dissemination of results will be via journal articles and conference presentations. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Temperature dependence of the properties of DBR mirrors used in surface normal optoelectronic devices

NASA Technical Reports Server (NTRS)

Dudley, J. J.; Crawford, D. L.; Bowers, J. E.

1992-01-01

The variation in the center wavelength of distributed Bragg reflectors used in optoelectronic devices, such as surface emitting lasers and Fabry-Perot modulators, is measured as the temperature of the mirrors changes over the range 25 C to 105 C. An analytic expression for the shift in center wavelength with temperature is presented. The mirrors measured are made of InP/InGaAsP, GaAs/AlAs, and Si/SiN(x). The linear shifts in center wavelength are 0.110 +/- 0.003 nm/C, 0.087 +/- 0.003 nm/C, and 0.067 +/- 0.007 nm/C for the InP/InGaAsP, GaAs/AlAs, and Si/SiN mirrors, respectively. Based on these data, the change in penetration depth with temperature is calculated.

Research on a novel composite structure Er³⁺-doped DBR fiber laser with a π-phase shifted FBG.

PubMed

Zhao, Yanjie; Chang, Jun; Wang, Qingpu; Ni, Jiasheng; Song, Zhiqiang; Qi, Haifeng; Wang, Chang; Wang, Pengpeng; Gao, Liang; Sun, Zhihui; Lv, Guangping; Liu, Tongyu; Peng, Gangding

2013-09-23

A simple composite cavity structure Er³⁺-doped fiber laser was proposed and demonstrated experimentally. The resonant cavity consists of a pair of uniform fiber Bragg gratings (FBGs) and a π-phase shifted FBG. By introducing the π-phase shifted FBG into the cavity as the selective wavelength component, it can increase the effective length of the laser cavity and suppress the multi-longitudinal modes simultaneously. The narrow linewidth of 900 Hz and low RIN of -95 dB/Hz were obtained. And the lasing wavelength was rather stable with the pump power changing. The SMRS was more than 67 dB. The results show that the proposed fiber laser has a good performance and considerable potential application for fiber sensor and optical communication.

Athermal operation of multi-section slotted tunable lasers.

PubMed

Wallace, M J; O'Reilly Meehan, R; Enright, R; Bello, F; McCloskey, D; Barabadi, B; Wang, E N; Donegan, J F

2017-06-26

Two distinct athermal bias current procedures based on thermal tuning are demonstrated for a low-cost, monotlithic, three section slotted single mode laser, achieving mode-hop free wavelength stability of ± 0.04 nm / 5 GHz over a temperature range of 8-47 °C. This is the first time that athermal performance has been demonstrated for a three-section slotted laser with simple fabrication, and is well within the 50 GHz grid spacing specified for DWDM systems. This performance is similar to experiments on more complex DS-DBR lasers, indicating that strong athermal performance can be achieved using our lower-cost three section devices. An analytical model and thermoreflectance measurements provide further insight into the operation of multi-section lasers and lay the foundation for an accurate predictive tool for optimising such devices for athermal operation.

Oxide-apertured VCSEL with short period superlattice

NASA Astrophysics Data System (ADS)

Li, Lin; Zhong, Jingchang; Zhang, Yongming; Su, Wei; Zhao, Yingjie; Yan, Changling; Hao, Yongqin; Jiang, Xiaoguang

2004-12-01

Novel distributed Bragg reflectors (DBRs) with 4.5 pairs of GaAs/AlAs short period superlattice (SPS) used in oxide-apertured vertical-cavity surface-emitting lasers (VCSELs) were designed. The structure of a 22-period Al_(0.9)Ga_(0.1)As (69.5 nm)/4.5-pair [GaAs (10 nm)-AlAs (1.9 nm)] DBR was grown on an n+ GaAs substrate (100) 2 deg. off toward <111>A by molecular beam epitaxy. The emitting wavelength was 850 nm with low threshold current of about 2 mA, corresponding to the threshold current density of 2 kA/cm2. The maximum output power was more than 1 mW. The VCSEL device temperature was increased by heating ambient temperature from 20 to 100 (Celsius degree) and the threshold current increased slowly with the increase of temperature.

Improved wavelength coded optical time domain reflectometry based on the optical switch.

PubMed

Zhu, Ninghua; Tong, Youwan; Chen, Wei; Wang, Sunlong; Sun, Wenhui; Liu, Jianguo

2014-06-16

This paper presents an improved wavelength coded time-domain reflectometry based on the 2 × 1 optical switch. In this scheme, in order to improve the signal-noise-ratio (SNR) of the beat signal, the improved system used an optical switch to obtain wavelength-stable, low-noise and narrow optical pulses for probe and reference. Experiments were set up to demonstrate a spatial resolution of 2.5m within a range of 70km and obtain the beat signal with line width narrower than 15 MHz within a range of 50 km in fiber break detection. A system for wavelength-division-multiplexing passive optical network (WDM-PON) monitoring was also constructed to detect the fiber break of different channels by tuning the current applied on the gating section of the distributed Bragg reflector (DBR) laser.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brummer, Gordie, E-mail: gbrummer@bu.edu; Photonics Center, Boston University, Boston, Massachusetts 02215; Nothern, Denis

Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum ofmore » 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.« less

Temporal Response of Dilute Nitride Multi-Quantum-Well Vertical Cavity Enhanced Photodetector

NASA Astrophysics Data System (ADS)

Nordin, M. S.; Sarcan, F.; Gunes, M.; Boland-Thoms, A.; Erol, A.; Vickers, A. J.

2018-01-01

The temporal response characteristics of a GaInNAs-based vertical resonant cavity enhanced photodetector device are presented for operation at λ ≈ 1.3 μm. The absorption layers of the device are composed of nine 7-nm-thick Ga0.65In0.35N0.02As0.98 quantum wells and are sandwiched between top and bottom AlGaAs/GaAs distributed Bragg reflectors (DBRs). The temperature dependence of the transient photoconductivity (TPC) under different light intensities and bias voltages is reported. Photoluminescence measurements were also performed on structures with and without the top DBR to determine their optical response under continuous illumination. The response time was measured using excitation from a 1047-nm pulsed neodymium-doped yttrium lithium fluoride laser with pulse width of 500 ps and repetition rate of 1 kHz. The rise time of the TPC was 2.27 ns at T = 50 K, decreasing to 1.79 ns at T = 300 K. The TPC decay time was 25.44 ns at T = 50 K, decreasing to 16.58 ns at T = 300 K. With detectivity of 2.28 × 10^{10} {cm}√ {Hz} / {W} and noise-equivalent power of 2.45 × 10^{ - 11} {W/}√ {Hz} , the proposed device is faster and more sensitive with better signal-to-noise ratio compared with other GaInNAs-based resonant cavity enhanced photodetectors (RCEPDs) for operation at 1.3 μm.

Long-wavelength (1.3-1.5 micron) quantum dot lasers based on GaAs

NASA Astrophysics Data System (ADS)

Kovsh, Alexey R.; Ledentsov, Nikolai N.; Mikhrin, Sergei S.; Zhukov, Alexey E.; Livshits, Daniil A.; Maleev, Nikolay A.; Maximov, Mikhail V.; Ustinov, Victor M.; Gubenko, Alexey E.; Gadjiev, Igor M.; Portnoi, Efim L.; Wang, Jyh Shyang; Chi, Jim Y.; Ouyang, Donald N.; Bimberg, Dieter; Lott, James A.

2004-06-01

The molecular beam epitaxy of self-assembled quantum dots (QDs) has reached a level such that the principal advantages of QD lasers can now be fully realized. We overview the most important recent results achieved to date including excellent device performance of 1.3 μm broad area and ridge waveguide lasers (Jth<150A/cm2, Ith=1.4 mA, differential efficiency above 70%, CW 300 mW single lateral mode operation), suppression of non-linearity of QD lasers, which results to improved beam quality, reduced wavelength chirp and sensitivity to optical feedback. Effect of suppression of side wall recombination in QD lasers is also described. These effects give a possibility to further improve and simplify processing and fabrication of laser modules targeting their cost reduction. Recent realization of 2 mW single mode CW operation of QD VCSEL with all-semiconductor DBR is also presented. Long-wavelength QD lasers are promising candidate for mode-locking lasers for optical computer application. Very recently 1.7-ps-wide pulses at repetition rate of 20 GHz were obtained on mode-locked QD lasers with clear indication of possible shortening of pulse width upon processing optimization. First step of unification of laser technology for telecom range with QD-lasers grown on GaAs has been done. Lasing at 1.5 μm is achieved with threshold current density of 0.8 kA/cm2 and pulsed output power 7W.

Visible-wavelength semiconductor lasers and arrays

DOEpatents

Schneider, R.P. Jr.; Crawford, M.H.

1996-09-17

The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1{lambda}) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%. 5 figs.

Visible-wavelength semiconductor lasers and arrays

DOEpatents

Schneider, Jr., Richard P.; Crawford, Mary H.

1996-01-01

A visible semiconductor laser. The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1.lambda.) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%.

Efficient generation of 1.9  W yellow light by cascaded frequency doubling of a distributed Bragg reflector tapered diode.

PubMed

Hansen, A K; Christensen, M; Noordegraaf, D; Heist, P; Papastathopoulos, E; Loyo-Maldonado, V; Jensen, O B; Skovgaard, P M W

2016-11-10

Watt-level yellow emitting lasers are interesting for medical applications, due to their high hemoglobin absorption, and for efficient detection of certain fluorophores. In this paper, we demonstrate a compact and robust diode-based laser system in the yellow spectral range. The system generates 1.9 W of single-frequency light at 562.4 nm by cascaded single-pass frequency doubling of the 1124.8 nm emission from a distributed Bragg reflector (DBR) tapered laser diode. The absence of a free-space cavity makes the system stable over a base-plate temperature range of 30 K. At the same time, the use of a laser diode enables the modulation of the pump wavelength by controlling the drive current. This is utilized to achieve a power modulation depth above 90% for the second harmonic light, with a rise time below 40  μs.

Integration of GaAs-based VCSEL array on SiN platform with HCG reflectors for WDM applications

NASA Astrophysics Data System (ADS)

Kumari, Sulakshna; Gustavsson, Johan S.; Wang, Ruijun; Haglund, Emanuel P.; Westbergh, Petter; Sanchez, Dorian; Haglund, Erik; Haglund, Åsa; Bengtsson, Jörgen; Le Thomas, Nicolas; Roelkens, Gunther; Larsson, Anders; Baets, Roel

2015-02-01

We present a GaAs-based VCSEL structure, BCB bonded to a Si3N4 waveguide circuit, where one DBR is substituted by a free-standing Si3N4 high-contrast-grating (HCG) reflector realized in the Si3N4 waveguide layer. This design enables solutions for on-chip spectroscopic sensing, and the dense integration of 850-nm WDM data communication transmitters where individual channel wavelengths are set by varying the HCG parameters. RCWA shows that a 300nm-thick Si3N4 HCG with 800nm period and 40% duty cycle reflects strongly (<99%) over a 75nm wavelength range around 850nm. A design with a standing-optical-field minimum at the III-V/airgap interface maximizes the HCG's influence on the VCSEL wavelength, allowing for a 15-nm-wide wavelength setting range with low threshold gain (<1000 cm-1).

First-Principle Study of the Optical Properties of Dilute-P GaN1-xPx Alloys.

PubMed

Borovac, Damir; Tan, Chee-Keong; Tansu, Nelson

2018-04-16

An investigation on the optical properties of dilute-P GaN 1-x P x alloys by First-Principle Density Functional Theory (DFT) methods is presented, for phosphorus (P) content varying from 0% up to 12.5%. Findings on the imaginary and real part of the dielectric function are analyzed and the results are compared with previously reported theoretical works on GaN. The complex refractive index, normal-incidence reflectivity and birefringence are presented and a difference in the refractive index in the visible regime between GaN and GaNP alloys of ~0.3 can be engineered by adding minute amounts of phosphorus, indicating strong potential for refractive index tunability. The optical properties of the GaN 1-x P x alloys indicate their strong potential for implementation in various III-nitride-based photonic waveguide applications and Distributed Bragg Reflectors (DBR).

Precise Control of Vertical-Cavity Surface-Emitting Laser Structural Growth Using Molecular Beam Epitaxy In Situ Reflectance Monitor

NASA Astrophysics Data System (ADS)

Mizutani, Mitsuhiro; Teramae, Fumiharu; Takeuchi, Kazutaka; Murase, Tatsunori; Naritsuka, Shigeya; Maruyama, Takahiro

2006-04-01

A vertical-cavity surface-emitting laser (VCSEL) was fabricated using a in situ reflectance monitor by molecular beam epitaxy (MBE). Both the center wavelength of the stop band of the distributed Bragg reflector (DBR) and the resonant wavelength of the optical cavity were successfully controlled using the monitor. However, these wavelengths shifted with decreasing substrate temperature after the growth, which could be reasonably explained by the temperature dependence of refractive index. Therefore, it is necessary to set a target wavelength at a growth temperature, considering the change. The desirable laser performance of the VCSEL fabricated from the wafer indicates marked increases in the controllability and reproducibility of growth with the aid of the in situ reflectance monitor. Since it can directly measure the optical properties of the grown layers, the reflectance monitor greatly helps in the fabrication of a structure with the designed optical performance.

1.55-μm InGaAs/InGaAlAs MQW vertical-cavity surface-emitting lasers with InGaAlAs/InP distributed Bragg reflectors

NASA Astrophysics Data System (ADS)

Xia, Jinan; Hoan O, Beom; Gol Lee, Seung; Hang Lee, El

2005-03-01

High-performance InGaAs/InGaAlAs multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) with InGaAlAs/InP distributed Bragg reflectors are proposed for operation at the wavelength of 1.55 μm. The lasers have good heat diffusion characteristic, large index contrast in DBRs, and weak temperature sensitivity. They could be fabricated either by metal-organic chemical vapor deposition (MOCVD) or by molecular beam epitaxy (MBE) growth. The laser light-current characteristics indicate that a suitable reflectivity of the DBR on the light output side in a laser makes its output power increase greatly and its lasing threshold current reduce significantly, and that a small VCSEL could output the power around its maximum for the output mirror at the reflectivity varying in a broader range than a large VCSEL does.

Porous silicon based micro-opto-electro-mechanical-systems (MOEMS) components for free space optical interconnects

NASA Astrophysics Data System (ADS)

Song, Da

2008-02-01

One of the major challenges confronting the current integrated circuits (IC) industry is the metal "interconnect bottleneck". To overcome this obstacle, free space optical interconnects (FSOIs) can be used to address the demand for high speed data transmission, multi-functionality and multi-dimensional integration for the next generation IC. One of the crucial elements in FSOIs system is to develop a high performance and flexible optical network to transform the incoming optical signal into a distributed set of optical signals whose direction, alignment and power can be independently controlled. Among all the optical materials for the realization of FSOI components, porous silicon (PSi) is one of the most promising candidates because of its unique optical properties, flexible fabrication methods and integration with conventional IC material sets. PSi-based Distributed Bragg Reflector (DBR) and Fabry-Perot (F-P) structures with unique optical properties are realized by electrochemical etching of silicon. By incorporating PSi optical structures with Micro-Opto-Electro-Mechanical-Systems (MOEMS), several components required for FSOI have been developed. The first type of component is the out-of-plane freestanding optical switch. Implementing a PSi DBR structure as an optically active region, the device can realize channel selection by changing the tilting angle of the micromirror supported by the thermal bimorph actuator. All the fabricated optical switches have reached kHz working frequency and life time of millions of cycles. The second type of component is the in-plane tunable optical filter. By introducing PSi F-P structure into the in-plane PSi film, a thermally tunable optical filter with a sensitivity of 7.9nm/V has been realized for add/drop optical signal selection. Also, for the first time, a new type of PSi based reconfigurable diffractive optical element (DOE) has been developed. By using patterned photoresist as a protective mask for electrochemical etching, the freestanding PSi-based MOEMS DOE has been created as a beam splitter to redistribute the incoming optical signal with onto desired detector arrays. All the developed devices are realized in array fashion and can be addressed and controlled individually. The combination of PSi and MOEMS opens the door for a new generation of silicon compatible optical interconnects.

Patterns in Nature Forming Patterns in Minds: An Evaluation of an Introductory Physics Unit

NASA Astrophysics Data System (ADS)

Sheaffer, Christopher Ryan

Educators are increasingly focused on the process over the content. In science especially, teachers want students to understand the nature of science and investigation. The emergence of scientific inquiry and engineering design teaching methods have led to the development of new teaching and evaluation methods that concentrate on steps in a process rather than facts in a topic. Research supports the notion that an explicit focus on the scientific process can lead to student science knowledge gains. In response to new research and standards many teachers have been developing teaching methods that seem to work well in their classrooms, but lack the time and resources to test them in other classroom environments. A high school Physics teacher (Bradford Hill) has developed a unit called Patterns in Nature (PIN) with objectives relating mathematical modeling to the scientific process. Designed for use in his large public school classroom, the unit was taken and used in a charter school with small classes. This study looks at specifically whether or not the PIN unit effectively teaches students how to graph the data they gather and fit an appropriate mathematical pattern, using that model to predict future measurements. Additionally, the study looks at the students' knowledge and views about the nature of science and the process of scientific investigation as it is affected by the PIN unit. Findings show that students are able to identify and apply patterns to data, but have difficulties explaining the meaning of the math. Students' show increases in their knowledge of the process of science, and the majority develop positive views about science in general. A major goal of this study is to place this unit in the cyclical process of Design-Based Research and allow for Pattern in Nature's continuous improvement, development and evaluation. Design-Based Research (DBR) is an approach that can be applied to the implementation and evaluation of classroom materials. This method incorporates the complexities of different contexts and changing treatments into the research methods and analysis. From the use of DBR teachers can understand more about how the designed materials affect the students. Others may be able to use the development and analysis of PIN study as a guide to look at similar aspects of science units developed elsewhere.

Extending the Direct Behavior Rating: An Examination of Schoolwide Behavior Ratings and Academic Engagement

ERIC Educational Resources Information Center

Bruhn, Allison; Barron, Sheila; Fernando, Josephine; Balint-Langel, Kinga

2018-01-01

Direct behavior ratings have been identified as a practical and feasible alternative to direct observation of behavior for monitoring behavioral progress. Despite the evidence of usability, there have been calls for further examination of direct behavior ratings using different behaviors and scales. To this end, we examined the ratings of…

Construction and Calibration of a Difference Frequency Laser Spectrometer and New THZ Frequency Measurements of water and Ammonia

NASA Technical Reports Server (NTRS)

Pearson, J. C.; Pickett, Herbert M.; Chen, Pin; Matsuura, Shuji; Blake, Geoffry A.

1999-01-01

A three laser system based on 852nm DBR lasers has been constructed and used to generate radiation in the 750 GHz to 1600 GHz frequency region. The system works by locking two of the three lasers to modes of an ultra low expansion Fabry-Perot cavity. The third laser is offset locked to one of the cavity locked lasers with conventional microwave techniques. The signal from the offset laser and the other cavity locked laser are injected into a Master Oscillator Power Amplifier (MOPA), amplified and focused on a low temperature grown GaAs photomixer, which radiates the difference frequency. The system has been calibrated with molecular lines to better than one part in 10(exp 7). In this paper we present the application of this system to the v(sub 2) in inversion band of Ammonia and the ground and v(sub 2) states of water. A discussion of the system design, the calibration and the new spectral measurements will be presented.

Resonant light emission from uniaxially tensile-strained Ge microbridges

NASA Astrophysics Data System (ADS)

Zhou, Peiji; Xu, Xuejun; Matsushita, Sho; Sawano, Kentarou; Maruizumi, Takuya

2018-04-01

A highly strained germanium microbridge is a promising platform for realizing monolithically integrated lasers on a silicon substrate. However, it remains challenging to combine it with optical resonators. Here, we have observed resonant light emission peaks with Q-factors of about 180 in room-temperature photoluminescence spectra from uniaxially tensile-strained germanium microbridges. These peaks are found to correspond to the resonance in Fabry–Perot (FP) cavities formed transversely to the uniaxial stress axis. On the basis of this phenomenon, we design a Fabry–Perot cavity by adding distributed Bragg reflectors (DBRs) laterally to the microbridge. With this design, the optical performance can be optimized without disturbing to the mechanical structure. A Q-factor as high as 1400 is obtained from numerical simulation. Moreover, we prove by theoretical analysis deduction and calculation that the lateral structure will not decrease the strain, unlike the on-pad DBR structure. The structure thus provides a promising solution for the realization of highly strained germanium lasers in the future.

Far-field emission characteristics and linewidth measurements of surface micro-machined MEMS tunable VCSELs

NASA Astrophysics Data System (ADS)

Paul, Sujoy; Gierl, Christian; Gründl, Tobias; Zogal, Karolina; Meissner, Peter; Amann, Markus-Christian; Küppers, Franko

2013-03-01

In this paper, we demonstrate for the first time the far-field experimental results and the linewidth characteris- tics for widely tunable surface-micromachined micro-electro-mechanical system (MEMS) vertical-cavity surface- emitting lasers (VCSELs) operating at 1550 nm. The fundamental Gaussian mode emission is confirmed by optimizing the radius of curvature of top distributed Bragg reflector (DBR) membrane and by choosing an ap- propriate diameter of circular buried tunnel junctions (BTJs) so that only the fundamental Gaussian mode can sustain. For these VCSELs, a mode-hop free continuous tuning over 100 nm has already been demonstrated, which is achieved by electro-thermal tuning of the MEMS mirror. The fiber-coupled optical power of 2mW over the entire tuning range has been reported. The singlemode laser emission has more than 40 dB of side-mode suppression ratio (SMSR). The smallest linewidth achieved with these of MEMS tunable VCSELs is 98MHz which is one order of magnitude higher than that of fixed-wavelength VCSELs.

End-to-end QoS bounds for RTP-based service subnetworks

NASA Astrophysics Data System (ADS)

Pitts, Jonathan M.; Schormans, John A.

1999-11-01

With the increasing focus on traffic prioritization to support voice-data integration in corporate intranets, practical methods are needed to dimension and manage cost efficient service partitions. This is particularly important for the provisioning of real time, delay sensitive services such as telephony and voice/video conferencing applications. Typically these can be provided over RTP/UDP/IP or ATM DBR/SBR bearers but, irrespective of the specific networking technology, the switches or routers need to implement some form of virtual buffer management with queue scheduling mechanisms to provide partitioning. The key requirement is for operators of such networks to be able to dimension the partitions and virtual buffer sizes for efficient resource utilization, instead of simply over-dimensioning. This paper draws on recent work at Queen Mary, University of London, supported by the UK Engineering and Physical Sciences Research Council, to investigate approximate analytical methods for assessing end to end delay variation bounds in cell based and packet based networks.

Cross-sectional imaging of extracted jawbone of a pig by optical coherence tomography

NASA Astrophysics Data System (ADS)

Tachikawa, Noriko; Yoshimura, Reiko; Ohbayashi, Kohji

2011-03-01

Dental implantation has become popular in dental treatments. Although careful planning is made to identify vital structures such as the inferior alveolar nerve or the sinus, as well as dimensions of the bone, prior to commencement of surgery, dental implantation is not fully free from risks. If a diagnostic tool is available to objectively measure bone feature before surgery and dimensions during surgery, considerable fraction of the risks may be avoided. Optical coherence tomography (OCT) is a candidate for the purpose, which enables cross-sectional imaging of bone. In this work, we performed in vitro cross-sectional imaging of extracted pig's jawbone with swept source OCT using superstructure-grating distributed Bragg reflector (SSG-DBR) laser as the source. The relatively long wavelength range of 1600nm of the laser is suitable for deeper bone imaging. We confirmed an image penetration depth of about 3 mm in physical length, which satisfies one of the criterions to apply OCT for in vivo diagnosis of bone during surgery.

AlGaAs phased array laser for optical communications

NASA Technical Reports Server (NTRS)

Carlson, N. W.

1989-01-01

Phased locked arrays of multiple AlGaAs diode laser emitters were investigated both in edge emitting and surface emitting configurations. CSP edge emitter structures, coupled by either evanescent waves or Y-guides, could not achieve the required powers (greater than or similar to 500 mW) while maintaining a diffraction limited, single lobed output beam. Indeed, although the diffraction limit was achieved in this type of device, it was at low powers and in the double lobed radiation pattern characteristic of out-of-phase coupling. Grating surface emitting (GSE) arrays were, therefore, investigated with more promising results. The incorporation of second order gratings in distribute Bragg reflector (DBR) structures allows surface emission, and can be configured to allow injection locking and lateral coupling to populate 2-D arrays that should be able to reach power levels commensurate with the needs of high performance, free space optical communications levels. Also, a new amplitude modulation scheme was developed for GSE array operation.

Electrically-Tunable Group Delays Using Quantum Wells in a Distributed Bragg Reflector

NASA Technical Reports Server (NTRS)

Nelson, Thomas R., Jr.; Loehr, John P.; Fork, Richard L.; Cole, Spencer; Jones, Darryl K.; Keys, Andrew

1999-01-01

There is a growing interest in the fabrication of semiconductor optical group delay lines for the development of phased arrays of Vertical-Cavity Surface-Emitting Lasers (VCSELs). We present a novel structure incorporating In(x)GA(1-x)As quantum wells in the GaAs quarter-wave layers of a GaAs/AlAs distributed Bragg reflector (DBR). Application of an electric field across the quantum wells leads to red shifting and peak broadening of the el-hhl exciton peak via the quantum-confined Stark effect. Resultant changes in the index of refraction thereby provide a means for altering the group delay of an incident laser pulse. We discuss the tradeoffs between the maximum amount of change in group delay versus absorption losses for such a device. We also compare a simple theoretical model to experimental results, and discuss both angle and position tuning of the BDR band edge resonance relative to the exciton absorption peak. The advantages of such monolithically grown devices for phased-array VCSEL applications will be detailed.

Movie Ratings and the Content of Adult Videos: The Sex-Violence Ratio.

ERIC Educational Resources Information Center

Yang, Ni; Linz, Daniel

1990-01-01

Quantifies sexual, violent, sexually violent, and prosocial behaviors in a sample of R-rated and X-rated videocassettes. Finds the predominant behavior in both X- and XXX-rated videos is sexual. Finds the predominant behavior in R-rated videos was violence followed by prosocial behavior. (RS)

Direct Behavior Rating: A Review of the Issues and Research in Its Development

ERIC Educational Resources Information Center

Chafouleas, Sandra M.

2011-01-01

The conceptual foundation for Direct Behavior Rating as a behavior assessment method is reviewed. A contemporary definition of Direct Behavior Rating is framed as combining strengths of systematic direct observation and behavior rating scales, which may result in a usable and defensible assessment tool for educators engaged in formative purposes.…

Interrater Agreement of the Individualized Behavior Rating Scale Tool

ERIC Educational Resources Information Center

Iovannone, Rose; Greenbaum, Paul E.; Wang, Wei; Dunlap, Glen; Kincaid, Don

2014-01-01

Data assessment is critical for determining student behavior change in response to individualized behavior interventions in schools. This study examined the interrater agreement of the Individualized Behavior Rating Scale Tool (IBRST), a perceptual direct behavior rating tool that was used by typical school personnel to record behavior occurrence…

Individual laboratory-measured discount rates predict field behavior

PubMed Central

Chabris, Christopher F.; Laibson, David; Morris, Carrie L.; Schuldt, Jonathon P.; Taubinsky, Dmitry

2009-01-01

We estimate discount rates of 555 subjects using a laboratory task and find that these individual discount rates predict inter-individual variation in field behaviors (e.g., exercise, BMI, smoking). The correlation between the discount rate and each field behavior is small: none exceeds 0.28 and many are near 0. However, the discount rate has at least as much predictive power as any variable in our dataset (e.g., sex, age, education). The correlation between the discount rate and field behavior rises when field behaviors are aggregated: these correlations range from 0.09-0.38. We present a model that explains why specific intertemporal choice behaviors are only weakly correlated with discount rates, even though discount rates robustly predict aggregates of intertemporal decisions. PMID:19412359

Individual laboratory-measured discount rates predict field behavior.

PubMed

Chabris, Christopher F; Laibson, David; Morris, Carrie L; Schuldt, Jonathon P; Taubinsky, Dmitry

2008-12-01

We estimate discount rates of 555 subjects using a laboratory task and find that these individual discount rates predict inter-individual variation in field behaviors (e.g., exercise, BMI, smoking). The correlation between the discount rate and each field behavior is small: none exceeds 0.28 and many are near 0. However, the discount rate has at least as much predictive power as any variable in our dataset (e.g., sex, age, education). The correlation between the discount rate and field behavior rises when field behaviors are aggregated: these correlations range from 0.09-0.38. We present a model that explains why specific intertemporal choice behaviors are only weakly correlated with discount rates, even though discount rates robustly predict aggregates of intertemporal decisions.

Contemporaneous and 1-year longitudinal prediction of children's prosocial behavior from sympathy and moral motivation.

PubMed

Malti, Tina; Gummerum, Michaela; Buchmann, Marlis

2007-09-01

The authors investigated the contemporaneous and longitudinal relations of children's (M age = 6.4 years) prosocial behavior to sympathy and moral motivation. Mothers and kindergarten teachers rated children's prosocial behavior. The authors measured sympathy via self- and adult reports. Moral motivation was assessed by children's attribution of emotions to hypothetical victimizers and self-as-victimizers and by moral reasoning after rule violations. Mother-rated prosocial behavior was contemporaneously and longitudinally related to sympathy. Moral motivation moderated the relation of sympathy to mother-rated prosocial behavior. Furthermore, boys' level of mother-rated prosocial behavior increased with level of moral motivation, whereas girls were high in mother-rated prosocial behavior, regardless of their level of moral motivation. Sympathy contemporaneously predicted kindergarten teacher-rated prosocial behavior.

Parent-rated externalizing behavior in preschoolers: the predictive utility of structured interviews, teacher reports, and classroom observations.

PubMed

Doctoroff, Greta L; Arnold, David H

2004-12-01

This study investigated multiple forms of home and school assessment as predictors of parent-rated behavior problems across a preschool year. Participants were a community sample of 79 preschool children, their parents, and their teachers. Parent ratings of behavior problems were obtained toward the beginning of the school year and approximately 6 months later. Behavior problems were also assessed early in the school year using parent structured interviews, teacher-rating scales, and classroom observations of problem and prosocial behavior. Consistent with hypotheses, each assessment method significantly predicted year-end parent ratings of behavior problems, even above initial ratings.

Teacher and TA Ratings of Preschoolers' Externalizing Behavior: Agreement and Associations with Observed Classroom Behavior

ERIC Educational Resources Information Center

Wolcott, Catherine Sanger; Williford, Amanda P.

2015-01-01

The present study investigated teachers' and teacher aides' (TAs) agreement in their ratings of preschoolers' externalizing behavior and their associations with observed classroom behavior for a sample of children at risk of developing a disruptive behavior disorder. One hundred twenty-two teachers rated 360 students' externalizing behavior in the…

Self-evaluation by adolescents in a psychiatric hospital school token program1

PubMed Central

Santogrossi, David A.; O'Leary, K. Daniel; Romanczyk, Raymond G.; Kaufman, Kenneth F.

1973-01-01

Nine adolescent boys with a history of high rates of disruptive classroom behavior were selected from a psychiatric hospital school and placed in a remedial reading class after school in which various factors in a token reinforcement program involving self-evaluation were investigated. The effects of self-evaluation, in the form of a rating the students gave themselves about the appropriateness of their classroom behavior, were first assessed. While the students' ratings of their own behavior correlated highly with the teacher's ratings and evaluations made by independent observers, the self-evaluations did not lead to a reduction in disruptive behavior. A token reinforcement program, in which the teacher rated the students' level of appropriate behavior and in which the students traded earned rating points for prizes, clearly led to a reduction of disruptive behavior. When the students were given the opportunity to evaluate their own behavior and to receive rewards in exchange for the evaluation, they returned to their former rates of disruptive behavior. PMID:16795409

Teachers' ratings of disruptive behaviors: the influence of halo effects.

PubMed

Abikoff, H; Courtney, M; Pelham, W E; Koplewicz, H S

1993-10-01

This study evaluated the accuracy of teachers' ratings and examined whether these ratings are influenced by halo effects. One hundred thirty-nine elementary school teachers viewed videotapes of what they believed were children in regular fourth-grade classrooms. In fact, the children were actors who followed prepared scripts that depicted a child engaging in behaviors characteristic of an attention-deficit hyperactivity disorder (ADHD), an oppositional defiant disorder or a normal youngster. The findings provide support for a bias that was unidirectional in nature. Specifically, teachers rated hyperactive behaviors accurately when the child behaved like an ADHD youngster. However, ratings of hyperactivity and of ADHD symptomatic behaviors were spuriously inflated when behaviors associated with oppositional defiant disorder occurred. In contrast, teachers rated oppositional and conduct problem behaviors accurately, regardless of the presence of hyperactive behaviors. The implications of these findings regarding diagnostic practices and rating scale formats are discussed.

The Role of Parenting Stress in Discrepancies between Parent and Teacher Ratings of Behavior Problems in Young Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Reed, Phil; Osborne, Lisa A.

2013-01-01

The study assessed whether teacher and parent ratings of child behavior problems were similar for children with autism spectrum disorders. Two informants rated child behaviors in the same home environment, and the degree to which parenting stress impacted the similarity of the ratings was assessed. Overall behavior problem ratings did not differ…

Same Constructs, Different Results: Examining the Consistency of Two Behavior-Rating Scales with Referred Preschoolers

ERIC Educational Resources Information Center

Myers, Carl L.; Bour, Jennifer L.; Sidebottom, Kristina J.; Murphy, Sara B.; Hakman, Melissa

2010-01-01

Broad-band or multidimensional behavior-rating scales are common tools for evaluating children. Two popular behavior-rating scales, the Behavior Assessment System for Children, Second Edition (BASC-2; Reynolds & Kamphaus, 2004) and the Child Behavior Checklist (CBCL; Achenbach & Rescorla, 2000), have undergone downward extensions so that…

Cultural and Ethnic Bias in Teacher Ratings of Behavior: A Criterion-Focused Review

ERIC Educational Resources Information Center

Mason, Benjamin A.; Gunersel, Adalet Baris; Ney, Emilie A.

2014-01-01

Behavior rating scales are indirect measures of emotional and social functioning used for assessment purposes. Rater bias is systematic error that may compromise the validity of behavior rating scale scores. Teacher bias in ratings of behavior has been investigated in multiple studies, but not yet assessed in a research synthesis that focuses on…

Was that cheating? Perceptions vary by sex, attachment anxiety, and behavior.

PubMed

Kruger, Daniel J; Fisher, Maryanna L; Edelstein, Robin S; Chopik, William J; Fitzgerald, Carey J; Stout, Sarah L

2013-02-13

We generated an inventory of 27 interpersonal behaviors and examined the extent to which participants judged each behavior as cheating on a long-term partner. We predicted variation in these judgments based on participant sex and attachment insecurity. Ratings for items ranged considerably; participants rated sexual behaviors as most indicative of cheating, then erotic behaviors, followed by behaviors consistent with a romantic relationship, and then behaviors related to financial support. Women rated ten items higher than did men, and men's ratings were higher on a minor financial support item. Higher attachment anxiety was associated with higher ratings for 18 of 27 behaviors; higher attachment avoidance was associated with lower scores on five items and higher scores on one item. Principle Axis Factoring identified three dimensions; sexual interaction, behaviors indicating close relationships, and casual social interaction. We discuss these results using the framework of attachment theory and sex-specific mating strategies.

Behavioral variability in an evolutionary theory of behavior dynamics.

PubMed

Popa, Andrei; McDowell, J J

2016-03-01

McDowell's evolutionary theory of behavior dynamics (McDowell, 2004) instantiates populations of behaviors (abstractly represented by integers) that evolve under the selection pressure of the environment in the form of positive reinforcement. Each generation gives rise to the next via low-level Darwinian processes of selection, recombination, and mutation. The emergent patterns can be analyzed and compared to those produced by biological organisms. The purpose of this project was to explore the effects of high mutation rates on behavioral variability in environments that arranged different reinforcer rates and magnitudes. Behavioral variability increased with the rate of mutation. High reinforcer rates and magnitudes reduced these effects; low reinforcer rates and magnitudes augmented them. These results are in agreement with live-organism research on behavioral variability. Various combinations of mutation rates, reinforcer rates, and reinforcer magnitudes produced similar high-level outcomes (equifinality). These findings suggest that the independent variables that describe an experimental condition interact; that is, they do not influence behavior independently. These conclusions have implications for the interpretation of high levels of variability, mathematical undermatching, and the matching theory. The last part of the discussion centers on a potential biological counterpart for the rate of mutation, namely spontaneous fluctuations in the brain's default mode network. © 2016 Society for the Experimental Analysis of Behavior.

Persisting behavior problems in extremely low birth weight adolescents.

PubMed

Taylor, H Gerry; Margevicius, Seunghee; Schluchter, Mark; Andreias, Laura; Hack, Maureen

2015-04-01

To describe behavior problems in extremely low birth weight (ELBW, <1000 g) adolescents born 1992 through 1995 based on parent ratings and adolescent self-ratings at age 14 years and to examine changes in parent ratings from ages 8-14. Parent ratings of behavior problems and adolescent self-ratings were obtained for 169 ELBW adolescents (mean birth weight 815 g, gestational age 26 wk) and 115 normal birth weight (NBW) controls at 14 years. Parent ratings of behavior at age 8 years were also available. Behavior outcomes were assessed using symptom severity scores and rates of scores above DSM-IV symptom cutoffs for clinical disorder. The ELBW group had higher symptom severity scores on parent ratings at age 14 years than NBW controls for inattentive attention-deficit hyperactivity disorder (ADHD), anxiety, and social problems (all p's < .01). Rates of parent ratings meeting DSM-IV symptom criteria for inattentive ADHD were also higher for the ELBW group (12% vs. 1%, p < .01). In contrast, the ELBW group had lower symptom severity scores on self-ratings than controls for several scales. Group differences in parent ratings decreased over time for ADHD, especially among females, but were stable for anxiety and social problems. Extremely low birth weight adolescents continue to have behavior problems similar to those evident at a younger age, but these problems are not evident in behavioral self-ratings. The findings suggest that parent ratings provide contrasting perspectives on behavior problems in ELBW youth and support the need to identify and treat these problems early in childhood.

A Teacher-Report Measure of Children's Task-Avoidant Behavior: A Validation Study of the Behavioral Strategy Rating Scale

ERIC Educational Resources Information Center

Zhang, Xiao; Nurmi, Jari-Erik; Kiuru, Noona; Lerkkanen, Marja-Kristiina; Aunola, Kaisa

2011-01-01

This study aims to validate a teacher-report measure of children's task-avoidant behavior, namely the Behavioral Strategy Rating Scale (BSRS), in a sample of 352 Finnish children. In each of the four waves from Kindergarten to Grade 2, teachers rated children's task-avoidant behavior using the BSRS, children completed reading and mathematics…

Appropriate and Inappropriate Instructional Behaviors for International Training.

ERIC Educational Resources Information Center

Burba, Fengjiao Ji; Petrosko, Joseph M.; Boyle, Mike A.

2001-01-01

Teacher behaviors were rated by 102 students from the United States, 142 from Asian cultures, and 73 from Western cultures (Canada, Europe). U.S. students rated clarity, enthusiasm, interaction, and spatial-behavioral communication more highly than Eastern students did. Western students rated all but spatial-behavioral communication more highly…

[Relationship among inattentive and hyperactive-impulsive behavior, aggression, and depression in Japanese elementary and junior high school students].

PubMed

Noda, Wataru; Okada, Ryo; Tani, Iori; Ohnishi, Masafumi; Naoto, Mochizuki; Nakajima, Syunji; Tsujii, Masatsugu

2013-06-01

The present study examines the relationship among inattentive, and hyperactive-impulsive behavior, aggression, and depression in elementary school and junior high school students. The participants were 3,885 children and their teachers and caregivers. Children's inattentive and hyperactive-impulsive behavior was rated by their teachers and caregivers (ADHD-RS). Children rated aggression (HAQ-C) and depression (DSRS-C) themselves. Inattentive and hyperactive-impulsive behavior rated by teachers and caregivers were positively related to aggression and depression. Inattention predicted higher levels of aggression and depression. Inattentive and hyperactive-impulsive behavior as rated by teachers was more highly related to depression than those behaviors as rated by caregivers. The relationships among inattentive, and hyperactive-impulsive behavior, aggression, and depression were almost the same for both elementary school and junior high school students. This study suggests the importance of assessing inattentive and hyperactive-impulsive behavior from multiple views to examine the relationship between inattentive and hyperactive-impulsive behavior and mental health problems.

Parenting Behaviors, Parent Heart Rate Variability, and Their Associations with Adolescent Heart Rate Variability.

PubMed

Graham, Rebecca A; Scott, Brandon G; Weems, Carl F

2017-05-01

Adolescence is a potentially important time in the development of emotion regulation and parenting behaviors may play a role. We examined associations among parenting behaviors, parent resting heart rate variability, adolescent resting heart rate variability and parenting behaviors as moderators of the association between parent and adolescent resting heart rate variability. Ninety-seven youth (11-17 years; 49.5 % female; 34 % African American, 37.1 % Euro-American, 22.6 % other/mixed ethnic background, and 7.2 % Hispanic) and their parents (n = 81) completed a physiological assessment and questionnaires assessing parenting behaviors. Inconsistent discipline and corporal punishment were negatively associated with adolescent resting heart rate variability, while positive parenting and parental involvement were positively associated. Inconsistent discipline and parental involvement moderated the relationship between parent and adolescent resting heart rate variability. The findings provide evidence for a role of parenting behaviors in shaping the development of adolescent resting heart rate variability with inconsistent discipline and parental involvement potentially influencing the entrainment of resting heart rate variability in parents and their children.

Relations between Response Trajectories on the Continuous Performance Test and Teacher-Rated Problem Behaviors in Preschoolers

PubMed Central

Allan, Darcey M.; Lonigan, Christopher J.

2014-01-01

Although both the Continuous Performance Test (CPT) and behavior rating scales are used in both practice and research to assess inattentive and hyperactive/impulsive behaviors, the correlations between performance on the CPT and teachers' ratings are typically only small-to-moderate. This study examined trajectories of performance on a low target-frequency visual CPT in a sample of preschool children and how these trajectories were associated with teacher-ratings of problem behaviors (i.e., inattention, hyperactivity/impulsivity [H/I], and oppositional/defiant behavior). Participants included 399 preschool children (Mean age = 56 months; 49.4% female; 73.7% White/Caucasian). An ADHD-rating scale was completed by teachers, and the CPT was completed by the preschoolers. Results showed that children's performance across four temporal blocks on the CPT was not stable across the duration of the task, with error rates generally increasing from initial to later blocks. The predictive relations of teacher-rated problem behaviors to performance trajectories on the CPT were examined using growth curve models. Higher rates of teacher-reported inattention and H/I were uniquely associated with higher rates of initial omission errors and initial commission errors, respectively. Higher rates of teacher-reported overall problem behaviors were associated with increasing rates of omission but not commission errors during the CPT; however, the relation was not specific to one type of problem behavior. The results of this study indicate that the pattern of errors on the CPT in preschool samples is complex and may be determined by multiple behavioral factors. These findings have implications for the interpretation of CPT performance in young children. PMID:25419645

Relations between response trajectories on the continuous performance test and teacher-rated problem behaviors in preschoolers.

PubMed

Allan, Darcey M; Lonigan, Christopher J

2015-06-01

Although both the continuous performance test (CPT) and behavior rating scales are used in both practice and research to assess inattentive and hyperactive/impulsive behaviors, the correlations between performance on the CPT and teachers' ratings are typically only small-to-moderate. This study examined trajectories of performance on a low target-frequency visual CPT in a sample of preschool children and how these trajectories were associated with teacher-ratings of problem behaviors (i.e., inattention, hyperactivity/impulsivity [H/I], and oppositional/defiant behavior). Participants included 399 preschool children (mean age = 56 months; 49.4% female; 73.7% White/Caucasian). An attention deficit/hyperactivity disorder (ADHD) rating scale was completed by teachers, and the CPT was completed by the preschoolers. Results showed that children's performance across 4 temporal blocks on the CPT was not stable across the duration of the task, with error rates generally increasing from initial to later blocks. The predictive relations of teacher-rated problem behaviors to performance trajectories on the CPT were examined using growth curve models. Higher rates of teacher-reported inattention and H/I were uniquely associated with higher rates of initial omission errors and initial commission errors, respectively. Higher rates of teacher-reported overall problem behaviors were associated with increasing rates of omission but not commission errors during the CPT; however, the relation was not specific to 1 type of problem behavior. The results of this study indicate that the pattern of errors on the CPT in preschool samples is complex and may be determined by multiple behavioral factors. These findings have implications for the interpretation of CPT performance in young children. (c) 2015 APA, all rights reserved).

Designing new classes of high-power, high-brightness VECSELs

NASA Astrophysics Data System (ADS)

Moloney, J. V.; Zakharian, A. R.; Hader, J.; Koch, Stephan W.

2005-10-01

Optically-pumped vertical external cavity semiconductor lasers offer the exciting possibility of designing kW-class solid state lasers that provide significant advantages over their doped YAG, thin-disk YAG and fiber counterparts. The basic VECSEL/OPSL (optically-pumped semiconductor laser) structure consists of a very thin (approximately 6 micron thick) active mirror consisting of a DBR high-reflectivity stack followed by a multiple quantum well resonant periodic (RPG) structure. An external mirror (reflectivity typically between 94%-98%) provides conventional optical feedback to the active semiconductor mirror chip. The "cold" cavity needs to be designed to take into account the semiconductor sub-cavity resonance shift with temperature and, importantly, the more rapid shift of the semiconductor material gain peak with temperature. Thermal management proves critical in optimizing the device for serious power scaling. We will describe a closed-loop procedure that begins with a design of the semiconductor active epi structure. This feeds into the sub-cavity optimization, optical and thermal transport within the active structure and thermal transport though the various heat sinking elements. Novel schemes for power scaling beyond current record performances will be discussed.

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

NASA Astrophysics Data System (ADS)

Christensen, Mathias; Vilera, Mariafernanda; Noordegraaf, Danny; Hansen, Anders K.; Buß, Thomas; Jensen, Ole B.; Skovgaard, Peter M. W.

2018-02-01

A wide range of laser medical treatments are based on coagulation of blood by absorption of the laser radiation. It has, therefore, always been a goal of these treatments to maximize the ratio of absorption in the blood to that in the surrounding tissue. For this purpose lasers at 577 nm are ideal since this wavelength is at the peak of the absorption in oxygenated hemoglobin. Furthermore, 577 nm has a lower absorption in melanin when compared to green wavelengths (515 - 532 nm), giving it an advantage when treating at greater penetration depth. Here we present a laser system based on frequency doubling of an 1154 nm Distributed Bragg Reflector (DBR) tapered diode laser, emitting 1.1 W of single frequency and diffraction limited yellow light at 577 nm, corresponding to a conversion efficiency of 30.5%. The frequency doubling is performed in a single pass configuration using a cascade of two bulk non-linear crystals. The system is power stabilized over 10 hours with a standard deviation of 0.13% and the relative intensity noise is measured to be 0.064 % rms.

Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers

PubMed Central

Jirauschek, Christian; Huber, Robert

2015-01-01

We analyze the physics behind the newest generation of rapidly wavelength tunable sources for optical coherence tomography (OCT), retaining a single longitudinal cavity mode during operation without repeated build up of lasing. In this context, we theoretically investigate the currently existing concepts of rapidly wavelength-swept lasers based on tuning of the cavity length or refractive index, leading to an altered optical path length inside the resonator. Specifically, we consider vertical-cavity surface-emitting lasers (VCSELs) with microelectromechanical system (MEMS) mirrors as well as Fourier domain mode-locked (FDML) and Vernier-tuned distributed Bragg reflector (VT-DBR) lasers. Based on heuristic arguments and exact analytical solutions of Maxwell’s equations for a fundamental laser resonator model, we show that adiabatic wavelength tuning is achieved, i.e., hopping between cavity modes associated with a repeated build up of lasing is avoided, and the photon number is conserved. As a consequence, no fundamental limit exists for the wavelength tuning speed, in principle enabling wide-range wavelength sweeps at arbitrary tuning speeds with narrow instantaneous linewidth. PMID:26203373

Hazardous materials in aquatic environments of the Mississippi River Basin. Annual technical report, 30 December 1992--29 December 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-12-31

Tulane and Xavier Universities have singled out the environment as a major strategic focus for research and training for now and beyond the year 2000. In 1989, the Tulane/Xavier Center for Bioenvironmental Research (CBR) was established as the umbrella organization which coordinates environmental research at both universities. In December, 1992, the Tulane/Xavier DBR was awarded a five year grant to study pollution in the Mississippi River system. The ``Hazardous Materials in Aquatic Environments of the Mississippi River Basin`` project is a broad research and education program aimed at elucidating the nature and magnitude of toxic materials that contaminate aquatic environmentsmore » of the Mississippi River Basin. Studies include defining the complex interactions that occur during the transport of contaminants, the actual and potential impact on ecological systems and health, and the mechanisms through which these impacts might be remediated. The Mississippi River Basin represents a model system for analyzing and solving contamination problems that are found in aquatic systems world-wide. Individual papers have been processed separately for inclusion in the appropriate data bases.« less

Upstream vertical cavity surface-emitting lasers for fault monitoring and localization in WDM passive optical networks

NASA Astrophysics Data System (ADS)

Wong, Elaine; Zhao, Xiaoxue; Chang-Hasnain, Connie J.

2008-04-01

As wavelength division multiplexed passive optical networks (WDM-PONs) are expected to be first deployed to transport high capacity services to business customers, real-time knowledge of fiber/device faults and the location of such faults will be a necessity to guarantee reliability. Nonetheless, the added benefit of implementing fault monitoring capability should only incur minimal cost associated with upgrades to the network. In this work, we propose and experimentally demonstrate a fault monitoring and localization scheme based on a highly-sensitive and potentially low-cost monitor in conjunction with vertical cavity surface-emitting lasers (VCSELs). The VCSELs are used as upstream transmitters in the WDM-PON. The proposed scheme benefits from the high reflectivity of the top distributed Bragg reflector (DBR) mirror of optical injection-locked (OIL) VCSELs to reflect monitoring channels back to the central office for monitoring. Characterization of the fault monitor demonstrates high sensitivity, low bandwidth requirements, and potentially low output power. The added advantage of the proposed fault monitoring scheme incurs only a 0.5 dB penalty on the upstream transmissions on the existing infrastructure.

Highly reliable high speed 1.1μm-InGaAs/GaAsP-VCSELs

NASA Astrophysics Data System (ADS)

Hatakeyama, H.; Anan, T.; Akagawa, T.; Fukatsu, K.; Suzuki, N.; Tokutome, K.; Tsuji, M.

2009-02-01

In this paper, we describe high temperature operation of high speed 1.1μm-range oxide-confined vertical-cavity surfaceemitting lasers (VCSELs) for optical interconnection applications. For achieving high speed of over 25 Gbit/s under a high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operation at 100°C. We also examined reliability of the VCSELs via accelerated life tests. The result showed extremely long MTTF lifetime of about 10 thousand hours under an ambient temperature of 150°C and a bias current of about 19 kA/cm2, a reliability that either equals or surpasses that of conventional 850-nm VCSELs with 10 Gbit/s. Moreover, we revealed a typical failure mode of the device; the result of analysis indicated that the failure was caused by <110> dark line defects (DLDs) generated in the n-DBR layers under the current aperture area.

Convergent Validity with the BERS-2 Teacher Rating Scale and the Achenbach Teacher's Report Form: A Replication and Extension

ERIC Educational Resources Information Center

Benner, Gregory J.; Beaudoin, Kathleen; Mooney, Paul; Uhing, Brad M.; Pierce, Corey D.

2008-01-01

In the present study, we sought to extend instrument validation research for a strength-based emotional and behavior rating scale, the "Teacher Rating Scale of the Behavior and Emotional Rating Scale-Second Edition" (BERS-2; Epstein, M. H. (2004). "Behavioral and emotional rating scale" (2nd ed.). Austin, TX: PRO-ED) through…

Evaluating the Validity of the Nisonger Child Behavior Rating Form--Parent Version

ERIC Educational Resources Information Center

Norris, Megan; Lecavalier, Luc

2011-01-01

Youth with intellectual and developmental disabilities (IDD) experience high rates of emotional and behavior problems. The Nisonger Child Behavior Rating Form (NCBRF) is one of the few tools developed to assess these problems in this population. It consists of a 10-item Social Competence section and a 66-item Problem Behavior section. The goal of…

Using Mood Ratings and Mood Induction in Assessment and Intervention for Severe Problem Behavior.

ERIC Educational Resources Information Center

Carr, Edward G.; McLaughlin, Darlene Magito; Giacobbe-Grieco, Theresa; Smith, Christopher E.

2003-01-01

A study examined whether a correlation existed between mood ratings and subsequent display of problem behavior in eight adults with mental retardation. Results indicated that bad mood ratings were highly predictive of problem behavior. When an induction procedure to improve mood ratings was implemented, dramatic decreases in problem behaviors…

[Effects of family cohesion and adaptability on behavioral problems in preschool children].

PubMed

Wang, Yan-Ni; Xue, Hong-Li; Chen, Qian

2016-05-01

To investigate the effects of family cohesion and adaptability on behavioral problems in preschool children. The stratified cluster multistage sampling method was used to perform a questionnaire survey in the parents of 1 284 children aged 3-6 years in the urban area of Lanzhou, China. The general status questionnaire, Conners Child Behavior Checklist (Parent Symptom Question), and Family Adaptability and Cohesion Scale, Second edition, Chinese version (FACESII-CV) were used to investigate behavioral problems and family cohesion and adaptability. The overall detection rate of behavioral problems in preschool children was 17.13%. The children with different types of family cohesion had different detection rates of behavioral problems, and those with free-type family cohesion showed the highest detection rate of behavioral problems (40.2%). The children with different types of family adaptability also had different detection rates of behavioral problems, and those with stiffness type showed the highest detection rate of behavioral problems (25.1%). The behavioral problems in preschool children were negatively correlated with family cohesion and adaptability. During the growth of preschool children, family cohesion and adaptability have certain effects on the mental development of preschool children.

Behavioral Momentum Theory Fails to Account for the Effects of Reinforcement Rate on Resurgence

PubMed Central

Craig, Andrew R.; Shahan, Timothy A.

2017-01-01

The behavioral-momentum model of resurgence predicts reinforcer rates within a resurgence preparation should have three effects on target behavior. First, higher reinforcer rates in baseline (Phase 1) produce more persistent target behavior during extinction plus alternative reinforcement. Second, higher rate alternative reinforcement during Phase 2 generates greater disruption of target responding during extinction. Finally, higher rates of either reinforcement source should produce greater responding when alternative reinforcement is suspended in Phase 3. Recent empirical reports have produced mixed results in terms of these predictions. Thus, the present experiment further examined reinforcer-rate effects on persistence and resurgence. Rats pressed target levers for high-rate or low-rate variable-interval food during Phase 1. In Phase 2, target-lever pressing was extinguished, an alternative nose-poke became available, and nose-poking produced either high-rate variable-interval, low-rate variable-interval, or no (an extinction control) alternative reinforcement. Alternative reinforcement was suspended in Phase 3. For groups that received no alternative reinforcement, target-lever pressing was less persistent following high-rate than low-rate Phase-1 reinforcement. Target behavior was more persistent with low-rate alternative reinforcement than with high-rate alternative reinforcement or extinction alone. Finally, no differences in Phase-3 responding were observed for groups that received either high-rate or low-rate alternative reinforcement, and resurgence occurred only following high-rate alternative reinforcement. These findings are inconsistent with the momentum-based model of resurgence. We conclude this model mischaracterizes the effects of rein-forcer rates on persistence and resurgence of operant behavior. PMID:27193242

Heart rate and treatment effect in children with disruptive behavior disorders.

PubMed

Stadler, Christina; Grasmann, Dörte; Fegert, Jörg M; Holtmann, Martin; Poustka, Fritz; Schmeck, Klaus

2008-09-01

To examine whether children with disruptive behavior disorders (DBDs; hyperkinetic conduct disorder, conduct disorder, hyperkinetic disorder) characterized by low heart rate profit less from an intensive cognitive behavioral intervention aimed at reducing impulsive, oppositional and aggressive behavior problems. Basal heart rate was studied in twenty-three children (aged 7-12 years) with DBD at the beginning of intervention comprising an intensive day-care treatment and parent training. The disruptive behavior of the child was assessed before treatment and after termination (12 weeks later). Therapy responders and non-responders were compared in regard to heart rate and other risk factors (cognitive functioning and socio-economic status). Statistical analyses yielded evidence for a significant reduction of disruptive problem behaviors (aggression, delinquency) that is more prominent in DBD children with high heart rate scores compared to patients with low heart rate scores. Heart rate was significantly lower in children who did not profit from therapy. A logistic regression analysis revealed that heart rate is a significant predictor for therapy success whereas other risk factors had no impact on therapy success. Further studies investigating biological and psychosocial predictors of treatment effectiveness are necessary. In addition, it might be helpful to consider different subtypes of aggressive behavior for selecting the best possible treatment options.

What affects teacher ratings of student behaviors? The potential influence of teachers' perceptions of the school environment and experiences.

PubMed

Pas, Elise T; Bradshaw, Catherine P

2014-12-01

Teachers serve as the natural raters of students within the school and classroom contexts. Yet teachers' ratings of their students may vary based on these contextual factors. The current study explored the extent to which teacher perceptions of the school environment predict their longitudinal ratings of student behaviors. Data for this study come from 702 teachers in 42 elementary schools. Teachers self-reported their perceptions of the school context at a single time point, and provided ratings of their students' behavior via the Teacher Observation of Classroom Adaption-Checklist (TOCA-C) across three school years. Latent profile analysis identified three latent classes of teachers based on their ratings of school organizational health, burnout, and efficacy. A regression framework demonstrated an association between the baseline profiles in relation to TOCA-C ratings of student behavior across 3 years. Teachers with more favorable perceptions of the environment had lower initial ratings of concentration problems, disruptive behavior, and internalizing symptoms, and higher ratings of prosocial behaviors and family involvement. They also showed slower growth in their ratings of emotion dysregulation and greater increases of their ratings of family involvement over time. This work is particularly important for determining the extent to which teacher ratings may be biased by teacher and contextual factors, and may have implications for the identification of teachers who may rate students poorly over time.

Effect of Pediatric Behavioral Health Screening and Colocated Services on Ambulatory and Inpatient Utilization.

PubMed

Hacker, Karen A; Penfold, Robert B; Arsenault, Lisa N; Zhang, Fang; Soumerai, Stephen B; Wissow, Lawrence S

2015-11-01

The study sought to determine the impact of a pediatric behavioral health screening and colocation model on utilization of behavioral health care. In 2003, Cambridge Health Alliance, a Massachusetts public health system, introduced behavioral health screening and colocation of social workers sequentially within its pediatric practices. An interrupted time-series study was conducted to determine the impact on behavioral health care utilization in the 30 months after model implementation compared with the 18 months prior. Specifically, the change in trends of ambulatory, emergency, and inpatient behavioral health utilization was examined. Utilization data for 11,223 children ages ≥4 years 9 months to <18 years 3 months seen from 2003 to 2008 contributed to the study. In the 30 months after implementation of pediatric behavioral health screening and colocation, there was a 20.4% cumulative increase in specialty behavioral health visit rates (trend of .013% per month, p=.049) and a 67.7% cumulative increase in behavioral health primary care visit rates (trend of .019% per month, p<.001) compared with the expected rates predicted by the 18-month preintervention trend. In addition, behavioral health emergency department visit rates increased 245% compared with the expected rate (trend .01% per month, p=.002). After the implementation of a behavioral health screening and colocation model, more children received behavioral health treatment. Contrary to expectations, behavioral health emergency department visits also increased. Further study is needed to determine whether this is an effect of how care was organized for children newly engaged in behavioral health care or a reflection of secular trends in behavioral health utilization or both.

Behavioral Hypervolumes of Predator Groups and Predator-Predator Interactions Shape Prey Survival Rates and Selection on Prey Behavior

PubMed Central

Pruitt, Jonathan N.; Howell, Kimberly A.; Gladney, Shaniqua J.; Yang, Yusan; Lichtenstein, James L. L.; Spicer, Michelle Elise; Echeverri, Sebastian A.; Pinter-Wollman, Noa

2017-01-01

Predator-prey interactions often vary on the basis of the traits of the individual predators and prey involved. Here we examine whether the multidimensional behavioral diversity of predator groups shapes prey mortality rates and selection on prey behavior. We ran individual sea stars (Pisaster ochraceus) through three behavioral assays to characterize individuals’ behavioral phenotype along three axes. We then created groups that varied in the volume of behavioral space that they occupied. We further manipulated the ability of predators to interact with one another physically via the addition of barriers. Prey snails (Chlorostome funebralis) were also run through an assay to evaluate their predator avoidance behavior before their use in mesocosm experiments. We then subjected pools of prey to predator groups and recorded the number of prey consumed and their behavioral phenotypes. We found that predator-predator interactions changed survival selection on prey traits: when predators were prevented from interacting, more fearful snails had higher survival rates, whereas prey fearfulness had no effect on survival when predators were free to interact. We also found that groups of predators that occupied a larger volume in behavioral trait space consumed 35% more prey snails than homogeneous predator groups. Finally, we found that behavioral hypervolumes were better predictors of prey survival rates than single behavioral traits or other multivariate statistics (i.e., principal component analysis). Taken together, predator-predator interactions and multidimensional behavioral diversity determine prey survival rates and selection on prey traits in this system. PMID:28221831

Behavioral Hypervolumes of Predator Groups and Predator-Predator Interactions Shape Prey Survival Rates and Selection on Prey Behavior.

PubMed

Pruitt, Jonathan N; Howell, Kimberly A; Gladney, Shaniqua J; Yang, Yusan; Lichtenstein, James L L; Spicer, Michelle Elise; Echeverri, Sebastian A; Pinter-Wollman, Noa

2017-03-01

Predator-prey interactions often vary on the basis of the traits of the individual predators and prey involved. Here we examine whether the multidimensional behavioral diversity of predator groups shapes prey mortality rates and selection on prey behavior. We ran individual sea stars (Pisaster ochraceus) through three behavioral assays to characterize individuals' behavioral phenotype along three axes. We then created groups that varied in the volume of behavioral space that they occupied. We further manipulated the ability of predators to interact with one another physically via the addition of barriers. Prey snails (Chlorostome funebralis) were also run through an assay to evaluate their predator avoidance behavior before their use in mesocosm experiments. We then subjected pools of prey to predator groups and recorded the number of prey consumed and their behavioral phenotypes. We found that predator-predator interactions changed survival selection on prey traits: when predators were prevented from interacting, more fearful snails had higher survival rates, whereas prey fearfulness had no effect on survival when predators were free to interact. We also found that groups of predators that occupied a larger volume in behavioral trait space consumed 35% more prey snails than homogeneous predator groups. Finally, we found that behavioral hypervolumes were better predictors of prey survival rates than single behavioral traits or other multivariate statistics (i.e., principal component analysis). Taken together, predator-predator interactions and multidimensional behavioral diversity determine prey survival rates and selection on prey traits in this system.

Factor Analysis of the Preschool Behavioral and Emotional Rating Scale for Children in Head Start Programs

ERIC Educational Resources Information Center

Cress, Cynthia; Lambert, Matthew C.; Epstein, Michael H.

2016-01-01

Strength-based assessment of behaviors in preschool children provides evidence of emotional and behavioral skills in children, rather than focusing primarily on weaknesses identified by deficit-based assessments. The Preschool Behavioral and Emotional Rating Scales (PreBERS) is a normative assessment of emotional and behavioral strengths in…

Evolutionary Influences on Attribution and Affect

PubMed Central

Brown, Jennie; Trafimow, David

2017-01-01

Evolutionary theory was applied to Reeder and Brewer's schematic theory and Trafimow's affect theory to extend this area of research with five new predictions involving affect and ability attributions, comparing morality and ability attributions, gender differences, and reaction times for affect and attribution ratings. The design included a 2 (Trait Dimension Type: HR, PR) × 2 (Behavior Type: morality, ability) × 2 (Valence: positive, negative) × 2 (Replication: original, replication) × 2 (Sex: female or male actor) × 2 (Gender: female or male participant) × 2 (Order: attribution portion first, affect portion first) mixed design. All factors were within participants except the order and participant gender. Participants were presented with 32 different scenarios in which an actor engaged in a concrete behavior after which they made attributions and rated their affect in response to the behavior. Reaction times were measured during attribution and affect ratings. In general, the findings from the experiment supported the new predictions. Affect was related to attributions for both morality and ability related behaviors. Morality related behaviors received more extreme attribution and affect ratings than ability related behaviors. Female actors received stronger attribution and affect ratings for diagnostic morality behaviors compared to male actors. Male and female actors received similar attribution and affect ratings for diagnostic ability behaviors. Diagnostic behaviors were associated with lower reaction times than non-diagnostic behaviors. These findings demonstrate the utility of evolutionary theory in creating new hypotheses and empirical findings in the domain of attribution. PMID:29312092

Evolutionary Influences on Attribution and Affect.

PubMed

Brown, Jennie; Trafimow, David

2017-01-01

Evolutionary theory was applied to Reeder and Brewer's schematic theory and Trafimow's affect theory to extend this area of research with five new predictions involving affect and ability attributions, comparing morality and ability attributions, gender differences, and reaction times for affect and attribution ratings. The design included a 2 (Trait Dimension Type: HR, PR) × 2 (Behavior Type: morality, ability) × 2 (Valence: positive, negative) × 2 (Replication: original, replication) × 2 (Sex: female or male actor) × 2 (Gender: female or male participant) × 2 (Order: attribution portion first, affect portion first) mixed design. All factors were within participants except the order and participant gender. Participants were presented with 32 different scenarios in which an actor engaged in a concrete behavior after which they made attributions and rated their affect in response to the behavior. Reaction times were measured during attribution and affect ratings. In general, the findings from the experiment supported the new predictions. Affect was related to attributions for both morality and ability related behaviors. Morality related behaviors received more extreme attribution and affect ratings than ability related behaviors. Female actors received stronger attribution and affect ratings for diagnostic morality behaviors compared to male actors. Male and female actors received similar attribution and affect ratings for diagnostic ability behaviors. Diagnostic behaviors were associated with lower reaction times than non-diagnostic behaviors. These findings demonstrate the utility of evolutionary theory in creating new hypotheses and empirical findings in the domain of attribution.

The etiology of behavior problems in 7-year-old twins: substantial genetic influence and negligible shared environmental influence for parent ratings and ratings by same and different teachers.

PubMed

Saudino, Kimberly J; Ronald, Angelica; Plomin, Robert

2005-02-01

Parent ratings of behavior problems in childhood show substantial genetic influence and modest shared environmental influence. However, few studies have compared these results to teacher ratings and no previous studies have compared same-teacher ratings to different-teacher ratings. 3,714 7-year-old twin pairs in the Twins Early Development Study were rated by parents and teachers on the Strengths and Difficulties Questionnaire. Substantial heritability and negligible shared environmental influence were found for data from all three raters for total behavior problems, hyperactivity, prosocial behavior, peer problems, conduct problems, and emotional symptoms. Sex-limitation models revealed similar results for males and females, although there was some evidence for greater heritability for boys, especially when twins were rated by the same teacher.

Specific Language Impairment and Executive Functioning: Parent and Teacher Ratings of Behavior

ERIC Educational Resources Information Center

Wittke, Kacie; Spaulding, Tammie J.; Schechtman, Calli J.

2013-01-01

Purpose: The current study used the Behavior Rating Inventory of Executive Function--Preschool Version (BRIEF-P; Gioia, Espy, & Isquith, 2003), a rating scale designed to investigate executive behaviors in everyday activities, to examine the executive functioning of preschool children with specific language impairment (SLI) relative to their…

Problem Behavior and Heart Rate Reactivity in Adopted Adolescents: Longitudinal and Concurrent Relations

ERIC Educational Resources Information Center

Bimmel, Nicole; van IJzendoorn, Marinus H.; Bakermans-Kranenburg, Marian J.; Juffer, Femmie; De Geus, Eco J. C.

2008-01-01

The present longitudinal study examined resting heart rate and heart rate variability and reactivity to a stressful gambling task in adopted adolescents with aggressive, delinquent, or internalizing behavior problems and adopted adolescents without behavior problems (total N=151). Early-onset delinquent adolescents showed heart rate…

Concurrent Reinforcement Schedules for Problem Behavior and Appropriate Behavior: Experimental Applications of the Matching Law

ERIC Educational Resources Information Center

Borrero, Carrie S. W.; Vollmer, Timothy R.; Borrero, John C.; Bourret, Jason C.; Sloman, Kimberly N.; Samaha, Andrew L.; Dallery, Jesse

2010-01-01

This study evaluated how children who exhibited functionally equivalent problem and appropriate behavior allocate responding to experimentally arranged reinforcer rates. Relative reinforcer rates were arranged on concurrent variable-interval schedules and effects on relative response rates were interpreted using the generalized matching equation.…

Stability of Behavioral Ratings of Children with SLI.

ERIC Educational Resources Information Center

Redmond, Sean M.; Rice, Mabel L.

2002-01-01

A study investigated the long-term stability of the teacher and parent behavioral ratings of 37 children with specific language impairment. Results indicate diminishment in teacher-reported behavior problems in most areas of socioemotional development from kindergarten to second grade and increasing congruence between teacher and parent ratings.…

The Influence of Teacher-Student Conflict on Teacher Ratings of Children's Externalizing and Internalizing Behaviors: A Multitrait-Multimethod Factor Analytic Approach

ERIC Educational Resources Information Center

Wickerd, Garry Dean

2012-01-01

Teachers' ratings of problem behaviors are gathered as a matter of course in psychological evaluations of children. Teacher ratings are weighted heavily in the results of educational evaluations (Frick et al., 2010). With such heavy emphasis on teacher behavioral ratings, it is important to understand the extent to which conflict between…

Comparison between objective measures and parental behavioral rating scales of memory and attention in pediatric endocrinology patients.

PubMed

Limbers, Christine; Young, Danielle; Jernigan, Stephanie; Bryant, William; Stephen, Matt

2017-01-01

Behavioral rating scales represent one potential method for screening of cognitive functioning in routine clinical care. It is not yet known if objective performance based measures and behavioral rating scales of cognitive functioning completed by parents yield similar information in pediatric endocrinology patients. The purpose of the present study was to evaluate the associations between performance-based measures and behavioral rating scales of memory and attention/concentration completed by parents of pediatric patients with Type 1 Diabetes or obesity. The sample consisted of 73 pediatric patients with Type 1 Diabetes or obesity (BMI > 95th percentile) ages 6-16 years (mean age = 12.29 years) referred to an outpatient pediatric endocrinology clinic. Youth were administered the Wide Range Assessment of Memory and Learning (WRAML-2). Parents completed the Child Behavior Checklist (CBCL) and the PedsQL Cognitive Functioning Scale. Pearson's Product Moment Correlations were examined among the performance-based measures and behavioral rating scales. All intercorrelations between the performance-based measures and behavioral rating scales completed by parents were in the small range. The only statistically significant (P < 0.05) and approaching medium correlation was between the PedsQL Cognitive Functioning Scale and WRAML-2 Verbal Memory Index (r = 0.28). On behavioral rating scales and performance-based measures of visual memory and attention/concentration, our sample exhibited greater difficulties than healthy youth from previously published data (P < 0.05). One possible explanation for our findings is that behavioral rating scales of attention/concentration and memory completed by parents measure different aspects of cognitive functioning than performance based measures in pediatric patients with Type 1 Diabetes or obesity.

Caudate neuronal recording in freely behaving animals following acute and chronic dose response methylphenidate exposure

PubMed Central

Claussen, Catherine M; Dafny, Nachum

2016-01-01

The misuse and abuse of the psychostimulant, methylphenidate (MPD) the drug of choice in the treatment of attention deficit hyperactivity disorder (ADHD) has seen a sharp uprising in recent years among both youth and adults for its cognitive enhancing effects and for recreational purposes. This uprise in illicit use has lead to many questions concerning the long term consequences of MPD exposure. The objective of this study was to record animal behavior concomitantly with the caudate nucleus (CN) neuronal activity following acute and repetitive (chronic) dose response exposure to methylphenidate (MPD). A saline control and three MPD dose (0.6, 2.5, and 10.0 mg/kg) groups were used. Behaviorally, the same MPD dose in some animals following chronic MPD exposure elicited behavioral sensitization and other animals elicited behavioral tolerance. Based on this finding, the CN neuronal population recorded from animals expressing behavioral sensitization were also evaluated separately from CN neurons recorded from animals expressing behavioral tolerance to chronic MPD exposure, respectively. Significant differences in CN neuronal population responses between the behaviorally sensitized and the behaviorally tolerant animals was observed for the 2.5 and 10.0 mg/kg MPD exposed groups. For 2.5 mg/kg MPD, behaviorally sensitized animals responded by decreasing their firing rates while behaviorally tolerant animals showed mainly an increase in their firing rates. The CN neuronal responses recorded from the behaviorally sensitized animals following 10.0 mg/kg MPD responded by increasing their firing rates whereas the CN neuronal recordings from the behaviorally tolerant animals showed that approximately half decreased their firing rates in response to 10.0 mg/kg MPD exposure. The comparison of percentage change in neuronal firing rates showed that the behaviorally tolerant animals trended to exhibit increases in their neuronal firing rates at ED1 following initial MPD exposure and oppositely at ED10 MPD rechallenge. While the behaviorally sensitized animals in general increased in their percentage change of firing rats were observed following acute 10.0 mg/kg MPD and the behaviorally sensitized 10.0 mg/kg MPD animals and a robust increase in neuronal firing rates at ED1 and ED10 rechallenge. These results suggest the need to first individually analyze animal behavioral activity, and than to evaluate the neuronal responses to the drug based on the animals behavioral response to chronic MPD exposure. PMID:26101057

Violent film characters' portrayal of alcohol, sex, and tobacco-related behaviors.

PubMed

Bleakley, Amy; Romer, Daniel; Jamieson, Patrick E

2014-01-01

To determine the extent to which movies popular with adolescents feature characters who jointly engage in violence and other risk behaviors. We hypothesized that violent characters engage in other risk behaviors equally often in films rated appropriate for children over 12 (PG-13) and Restricted (R)-rated films. Content analysis of a sample of top-grossing movies from 1985 to 2010 (n = 390). We coded movies for the presence of at least 1 main character who was involved in violence and either sex, tobacco, or alcohol use within a 5-minute movie segment and throughout a film. Approximately 90% of the movies contained a segment with a main character involved in violence, and ~77% of the films had the same character engaging in at least 1 other risk behavior. A violent character was portrayed most often partaking in alcohol-related and sexual behaviors. G and PG movies had less co-occurrence than PG-13 or R-rated movies, but there was no statistical difference between PG-13 and R-rated movies with regards to violence co-occurring with other risk behaviors. These trends did not vary over time. Popular films that contain violent characters also show those characters engaging in other risk behaviors. Similar rates of co-occurrence between PG-13 and R-rated films suggest that the Motion Picture Association of America ratings system is not sensitive to the joint portrayal of violence and alcohol, sex, and tobacco-related risk behaviors. The on-screen clustering of violence with other risk behaviors is cause for concern and worthy of additional research.

Factor Structure of Child Behavior Scale Scores in Peruvian Preschoolers

ERIC Educational Resources Information Center

Meyer, Erin L.; Schaefer, Barbara A.; Soto, Cesar Merino; Simmons, Crystal S.; Anguiano, Rebecca; Brett, Jeremy; Holman, Alea; Martin, Justin F.; Hata, Heidi K.; Roberts, Kimberly J.; Mello, Zena R.; Worrell, Frank C.

2011-01-01

Behavior rating scales aid in the identification of problem behaviors, as well as the development of interventions to reduce such behavior. Although scores on many behavior rating scales have been validated in the United States, there have been few such studies in other cultural contexts. In this study, the structural validity of scores on a…

Preschool Children's Sleep and Wake Behavior: Effects of Massage Therapy.

ERIC Educational Resources Information Center

Field, Tiffany; And Others

1996-01-01

Preschool children received twice-weekly massages for five weeks. Compared to control children, the massaged children had better behavior ratings on mood state, vocalization, activity, and cooperation following massage on day one and throughout the study. Teachers rated their behavior more optimally, and their parents rated them as having less…

Using Rasch Rating Scale Methodology to Examine a Behavioral Screener for Preschoolers at Risk

ERIC Educational Resources Information Center

DiStefano, Christine; Greer, Fred W.; Kamphaus, R. W.; Brown, William H.

2014-01-01

A screening instrument used to identify young children at risk for behavioral and emotional difficulties, the Behavioral and Emotional Screening System Teacher Rating Scale-Preschool was examined. The Rasch Rating Scale Method was used to provide additional information about psychometric properties of items, respondents, and the response scale.…

Screening for Social, Emotional, and Behavioral Problems at Kindergarten Entry: Utility and Incremental Validity of Parent Report

ERIC Educational Resources Information Center

Owens, Julie Sarno; Storer, Jennifer; Holdaway, Alex S.; Serrano, Verenea J.; Watabe, Yuko; Himawan, Lina K.; Krelko, Rebecca E.; Vause, Katherine J.; Girio-Herrera, Erin; Andrews, Nina

2015-01-01

The current study examined the utility and incremental validity of parent ratings on the Strengths and Difficulties Questionnaire and Disruptive Behavior Disorders rating scale completed at kindergarten registration in identifying risk status as defined by important criterion variables (teacher ratings, daily behavioral performance, and quarterly…

Influences on the Congruence between Parents' and Teachers' Ratings of Young Children's Social Skills and Problem Behaviors

ERIC Educational Resources Information Center

Dinnebeil, Laurie A.; Sawyer, Brook E.; Logan, Jessica; Dynia, Jaclyn M.; Cancio, Edward; Justice, Laura M.

2013-01-01

A comprehensive research base exists concerning the congruence between parents' and teachers' ratings of the behavior of typically developing young children. However, little research has been conducted regarding the degree to which parents' and teachers' behavioral ratings of young children with disabilities are congruent. Additionally, previous…

Association between just world beliefs and perceptions of counterproductive workplace behaviors.

PubMed

Stieger, Stefan; Kastner, Cornelia K; Voracek, Martin; Furnham, Adrian

2011-04-01

320 adults rated 48 counterproductive workplace behaviors (CWBs) on a 9-point scale, from petty to serious offense, and also completed the Just World Beliefs scale. Ratings of the seriousness of the CWBs indicated considerable variability in perceptions, with theft and physical violence rated most strongly. A factor analysis yielded five interpretable factors. Older participants were more likely to rate as more serious all counterproductive workplace behaviors.

Fire-danger rating and observed wildfire behavior in the Northeastern United States.

Treesearch

Donald A. Haines; William A. Main; Albert J. Simard

1986-01-01

Compares the 1978 National Fire-Danger Rating System and its 20 fuel models, along with other danger rating systems, with observed fire behavior and rates the strengths and weaknesses of models and systems.

Heart Rate and Treatment Effect in Children with Disruptive Behavior Disorders

ERIC Educational Resources Information Center

Stadler, Christina; Grasmann, Dorte; Fegert, Jorg M.; Holtmann, Martin; Poustka, Fritz; Schmeck, Klaus

2008-01-01

Objective: To examine whether children with disruptive behavior disorders (DBDs; hyperkinetic conduct disorder, conduct disorder, hyperkinetic disorder) characterized by low heart rate profit less from an intensive cognitive behavioral intervention aimed at reducing impulsive, oppositional and aggressive behavior problems. Method: Basal heart rate…

The effects of instructions on mothers' ratings of child attention-deficit/hyperactivity disorder symptoms.

PubMed

Johnston, Charlotte; Weiss, Margaret; Murray, Candice; Miller, Natalie

2011-11-01

We examined whether instructional materials describing how to rate child ADHD symptoms would improve the accuracy of mothers' ratings of ADHD symptoms presented in standard child behavior stimuli, and whether instructions would be equally effective across a range of maternal depressive symptoms and family incomes. A community sample of 100 mothers with 5 to 12 year old sons were randomly assigned to either receive or not receive the instructions. All mothers watched standard video recordings of boys displaying nonproblem behavior, ADHD symptoms, ADHD plus oppositional behaviors, or ADHD plus anxious behaviors, and then rated the ADHD symptoms of the boys in the videos. These ratings were compared to ratings of the boys' ADHD symptoms made by objective coders. Results indicated an interaction such that the instructional materials improved the agreement between mothers' and coders' ratings, but only for mothers at lower family income levels. The instructional materials improved all mothers' open-ended responses regarding knowledge of ADHD. All mothers rated more ADHD symptoms in boys with comorbid oppositional or anxious behaviors, and this effect was not reduced by the instructional materials. The potential utility of these instructions to improve the accuracy of ratings of child ADHD symptoms is explored.

Efficacy of individualized social competence training for children with oppositional defiant disorders/conduct disorders: a randomized controlled trial with an active control group.

PubMed

Goertz-Dorten, Anja; Benesch, Christina; Berk-Pawlitzek, Emel; Faber, Martin; Hautmann, Christopher; Hellmich, Martin; Lindenschmidt, Timo; Schuh, Lioba; Stadermann, Rahel; Doepfner, Manfred

2018-03-28

Patient-focused cognitive-behavioral therapy in children with aggressive behavior, which uses group-based social skills training, has resulted in significant reductions in behavioral problems, with effect sizes in the small-to-medium range. However, effects of individually delivered treatments and effects on aggressive behavior and comorbid conditions rated from different perspectives, child functional impairment, child quality of life, parent-child relationship, and parental psychopathology have rarely been assessed. In a randomized controlled trial, 91 boys aged 6-12 years with a diagnosis of oppositional defiant disorder/conduct disorder and peer-related aggression were randomized to receive individually delivered social competence training (Treatment Program for Children with Aggressive Behavior, THAV) or to an active control involving group play that included techniques to activate resources and the opportunity to train prosocial interactions in groups (PLAY). Outcome measures were rated by parents, teachers, or clinicians. Mostly moderate treatment effects for THAV compared to PLAY were found in parent ratings and/or clinician ratings on aggressive behavior, comorbid symptoms, psychosocial impairment, quality of life, parental stress, and negative expressed emotions. In teacher ratings, significant effects were found for ADHD symptoms and prosocial behavior only. THAV is a specifically effective intervention for boys aged 6-12 years with oppositional defiant disorder/conduct disorder and peer-related aggressive behavior as rated by parents and clinicians.

Pathways to Suicidal Behaviors in Childhood

ERIC Educational Resources Information Center

Greening, Leilani; Stoppelbein, Laura; Fite, Paula; Dhossche, Dirk; Erath, Stephen; Brown, Jacqueline; Cramer, Robert; Young, Laura

2008-01-01

Path analyses were applied to test a model that includes internalizing and externalizing behavior problems as predictors of suicidal behaviors in children. Parents of an inpatient sample of boys (N = 87; M age = 9.81 years) rated the frequency of suicidal ideation and completed standardized measures of behavior problems. Blind raters rated the…

A Brief Measure of Children's Behavior Problems: The Behavior Rating Index for Children.

ERIC Educational Resources Information Center

Stiffman, Arlene R.; And Others

1984-01-01

Describes the development of the Behavior Rating Index for Children (BRIC), a 13-item summated category partition scale that provides a prothetic measure of children's behavior problems. Evaluation of the BRIC with 600 referred and nonreferred children suggested adequate reliability and validity. (JAC)

Charts for interpreting wildland fire behavior characteristics

Treesearch

Patricia L. Andrews; Richard C. Rothermel

1982-01-01

The fire characteristics chart is proposed as a graphical method ofpresenting two primary characteristics of fire behavior – spread rate and intensity. Its primary use is communicating and interpreting either site-specific predictions of fire behavior or National Fire-Danger Rating System (NFDRS) indexes and components. Rate of spread, heat per unit area, flame length...

A Cross-Cultural Comparison of Teacher Ratings of Child Adjustment and Behavioral Problems

ERIC Educational Resources Information Center

Rowe, Ellen W.; Rivers, Lanee; Kamphaus, Randy W.

2013-01-01

This study examines similarities and differences in teacher ratings of behavioral problems and adaptive skills between a sample of 320 students from Anguilla, BWI and 315 children from the United States of America using the Behavior Assessment System for Children (BASC; Reynolds & Kamphaus, 1992). The study also compared teacher ratings of…

Increases in Parent Attendance to Behavioral Parent Training Due to Concurrent Child Treatment Groups

ERIC Educational Resources Information Center

Jensen, Scott A.; Grimes, Lisa K.

2010-01-01

Though behavioral parent training has been demonstrated to be an effective intervention for child behavior problems, it continues to suffer from high attrition rates. Few variables have been found to predict or decrease high attrition rates from parent training classes. The present study found 43-52% increases in attendance rates for parents whose…

Gene-Environment Interaction in Teacher-Rated Internalizing and Externalizing Problem Behavior in 7- to 12-Year-Old Twins

ERIC Educational Resources Information Center

Lamb, Diane J.; Middeldorp, Christel M.; Van Beijsterveldt, Catarina E. M.; Boomsma, Dorret I.

2012-01-01

Background: Internalizing and externalizing problem behavior at school can have major consequences for a child and is predictive for disorders later in life. Teacher ratings are important to assess internalizing and externalizing problems at school. Genetic epidemiological studies on teacher-rated problem behavior are relatively scarce and the…

The Diagnostic Utility of Behavioral Checklists in Identifying Children with ADHD and Children with Working Memory Deficits

ERIC Educational Resources Information Center

Alloway, Tracy Packiam; Gathercole, Susan E.; Holmes, Joni; Place, Maurice; Elliott, Julian G.; Hilton, Kerry

2009-01-01

The present study investigated whether children with ADHD and those with working memory impairments have a common behavioral profile in the classroom. Three teacher checklists were used: the Conners' teacher rating scale (CTRS), the behavior rating inventory of executive function (BRIEF), and the working memory rating scale. The Conners'…

The Impact of Training on the Accuracy of Teacher-Completed Direct Behavior Ratings (DBRs)

ERIC Educational Resources Information Center

LeBel, Teresa J.; Kilgus, Stephen P.; Briesch, Amy M.; Chafouleas, Sandra

2010-01-01

The purpose of this study was to investigate the effects of three levels of training (direct, indirect, and none) on teachers' ability to accurately rate video of student behavior. Direct and indirect training groups received instructional sessions on direct behavior ratings (DBRs), with the direct training group receiving opportunities for…

Stability in Infant Frontal Asymmetry as a Predictor of Toddlerhood Internalizing and Externalizing Behaviors

PubMed Central

Smith, Cynthia L.; Bell, Martha Ann

2013-01-01

Stability in frontal brain electrical activity (i.e., electroencephalographic or EEG) asymmetry at 10 and 24 months was examined with respect to maternal ratings of internalizing and externalizing behaviors at 30 months in a sample of 48 children. Children with stable left frontal EEG asymmetry during infancy were rated higher in externalizing behaviors by their mothers, whereas children with stable right frontal EEG asymmetry were rated higher in internalizing behaviors. These findings highlight the need to focus on the early stability in physiological measures that may be implicated later in developing behavioral problems. PMID:20175143

Simultaneous assessment of autonomic function and anxiety-related behavior in BALB/c and C57BL/6 mice.

PubMed

Depino, Amaicha Mara; Gross, Cornelius

2007-02-27

In humans, anxiety is accompanied by changes in autonomic nervous system function, including increased heart rate, body temperature, and blood pressure, and decreased heart rate variability. In rodents, anxiety is inferred by examining anxiety-related behavioral responses such as avoidance and freezing, and more infrequently by assessing autonomic responses to anxiogenic stimuli. However, few studies have simultaneously measured behavioral and autonomic responses to aversive stimuli in rodents and it remains unclear whether autonomic measures are reliable correlates of anxiety-related behavior in these animal models. Here we recorded for the first time heart rate and body temperature in freely moving BALB/c and C57BL/6 mice during exposure to an unfamiliar environment. Our data show that upon exposure to a novel open field, BALB/c mice showed increased anxiety-related behavior, reduced heart rate and higher heart rate variability (HRV) when compared with C57BL/6 mice. Regression analysis revealed a significant correlation between both heart rate and long-term HRV measures and locomotor activity and time spent in the center of the open field, but no correlation between body temperature and any behavioral variables. In the free exploration test, in which animals were allowed direct access to a novel environment from a familiar environment without experimenter handling, significant correlations were found only between heart rate and total locomotor activity, but not time spent in the unfamiliar chamber despite increased anxiety-related behavior in BALB/c mice. These findings demonstrate that increased anxiety-related behavior in BALB/c mice is not associated with specific changes in heart rate, HRV, or body temperature.

User’s Guide for Tactical Thinking Behaviorally Anchored Rating Scales

DTIC Science & Technology

2006-06-01

Shafer , J., Ross, K. G., Cox, D. A., & Shadrick, S . B. (2005). A behaviorally anchored assessment tool to measure tactical thinking proficiency. Paper...NUMBER User’s Guide for Tactical Thinking Behaviorally Anchored Rating W74V8H-04-C-0018 Scales 5b. PROGRAM ELEMENT NUMBER 622785 6. AUTHOR( S ) 5c...cognition by observing and rating behaviors . Phillips, Shafer , Ross, Cox, and Shadrick (2005) describe the process by which the T- BARS were developed. This

Cognitive behavior therapy for eating disorders versus normalization of eating behavior.

PubMed

Södersten, P; Bergh, C; Leon, M; Brodin, U; Zandian, M

2017-05-15

We examine the science and evidence supporting cognitive behavior therapy (CBT) for the treatment of bulimia nervosa and other eating disorders. Recent trials focusing on the abnormal cognitive and emotional aspects of bulimia have reported a remission rate of about 45%, and a relapse rate of about 30% within one year. However, an early CBT trial that emphasized the normalization of eating behavior had a better outcome than treatment that focused on cognitive intervention. In support of this finding, another treatment, that restores a normal eating behavior using mealtime feedback, has an estimated remission rate of about 75% and a relapse rate of about 10% over five years. Moreover, when eating behavior was normalized, cognitive and emotional abnormalities were resolved at remission without cognitive therapy. The critical aspect of the CBT treatment of bulimia nervosa therefore may actually have been the normalization of eating behavior. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Development of an Observational Rating Schedule for Preschool Children's Peer-Group Behavior.

ERIC Educational Resources Information Center

Cunningham, Jo Lynn; Boger, Robert P.

The feasiblity of an observational rating scale which would provide objective, reliable and quantifiable measures of social and affective behavior was investigated. The Observation of Socialization Behavior (OSB), focusing on peer-group behavior of pre-school children and designed for use in unstructured situations was developed. Two forms of the…

An International Assessment of the Emotional and Behavioral Strengths of Youth

ERIC Educational Resources Information Center

Lappalainen, Kristiina; Savolainen, Hannu; Kuorelahti, Matti; Epstein, Michael H.

2009-01-01

The assessment of emotional and behavioral strengths has been identified as an important part of the assessment process for children referred for specialized services. The Behavioral and Emotional Rating Scale-2 (BERS-2; Epstein, Behavioral and Emotional Rating Scale: a strength-based approach to assessment. PRO-Ed, Austin, TX, 2004) was developed…

Factors associated with DSM-5 severity level ratings for autism spectrum disorder.

PubMed

Mazurek, Micah O; Lu, Frances; Macklin, Eric A; Handen, Benjamin L

2018-02-01

The newest edition of the Diagnostic and Statistical Manual of Mental Disorders (5th ed., DSM-5) introduced substantial changes to the diagnostic criteria for autism spectrum disorder, including new severity level ratings for social communication and restricted and repetitive behavior domains. The purpose of this study was to evaluate the use of these new severity ratings and to examine their relation to other measures of severity and clinical features. Participants included 248 children with autism spectrum disorder who received diagnostic evaluations at one of six Autism Treatment Network sites. Higher severity ratings in both domains were associated with younger age, lower intelligence quotient, and greater Autism Diagnostic Observation Schedule-Second Edition domain-specific symptom severity. Greater restricted and repetitive behavior severity was associated with higher parent-reported stereotyped behaviors. Severity ratings were not associated with emotional or behavioral problems. The new DSM-5 severity ratings in both domains were significantly associated with behavioral observations of autism severity but not with measures of other behavioral or emotional symptoms. However, the strong associations between intelligence quotient and DSM-5 severity ratings in both domains suggest that clinicians may be including cognitive functioning in their overall determination of severity. Further research is needed to examine clinician decision-making and interpretation of these specifiers.

One (rating) from many (observations): Factors affecting the individual assessment of voice behavior in groups.

PubMed

Podsakoff, Nathan P; Maynes, Timothy D; Whiting, Steven W; Podsakoff, Philip M

2015-07-01

This article reports an investigation into how individuals form perceptions of overall voice behavior in group contexts. More specifically, the authors examine the effect of the proportion of group members exhibiting voice behavior in the group, the frequency of voice events in the group, and the measurement item referent (group vs. individual) on an individual's ratings of group voice behavior. In addition, the authors examine the effect that measurement item referent has on the magnitude of the relationship observed between an individual's ratings of group voice behavior and perceptions of group performance. Consistent with hypotheses, the results from 1 field study (N = 220) and 1 laboratory experiment (N = 366) indicate that: (a) When group referents were used, raters relied on the frequency of voice events (and not the proportion of group members exhibiting voice) to inform their ratings of voice behavior, whereas the opposite was true when individual-referent items were used, and (b) the magnitude of the relationship between observers' ratings of group voice behavior and their perceptions of group performance was higher when raters used group-referent, as opposed to an individual-referent, items. The authors discuss the implications of their findings for scholars interested in studying behavioral phenomena occurring in teams, groups, and work units in organizational behavior research. (c) 2015 APA, all rights reserved).

Selecting Strategies to Reduce High-Risk Unsafe Work Behaviors Using the Safety Behavior Sampling Technique and Bayesian Network Analysis.

PubMed

Ghasemi, Fakhradin; Kalatpour, Omid; Moghimbeigi, Abbas; Mohammadfam, Iraj

2017-03-04

High-risk unsafe behaviors (HRUBs) have been known as the main cause of occupational accidents. Considering the financial and societal costs of accidents and the limitations of available resources, there is an urgent need for managing unsafe behaviors at workplaces. The aim of the present study was to find strategies for decreasing the rate of HRUBs using an integrated approach of safety behavior sampling technique and Bayesian networks analysis. A cross-sectional study. The Bayesian network was constructed using a focus group approach. The required data was collected using the safety behavior sampling, and the parameters of the network were estimated using Expectation-Maximization algorithm. Using sensitivity analysis and belief updating, it was determined that which factors had the highest influences on unsafe behavior. Based on BN analyses, safety training was the most important factor influencing employees' behavior at the workplace. High quality safety training courses can reduce the rate of HRUBs about 10%. Moreover, the rate of HRUBs increased by decreasing the age of employees. The rate of HRUBs was higher in the afternoon and last days of a week. Among the investigated variables, training was the most important factor affecting safety behavior of employees. By holding high quality safety training courses, companies would be able to reduce the rate of HRUBs significantly.

Symptoms of Persistent Behavior Problems in Children With Mild Traumatic Brain Injury.

PubMed

Taylor, H Gerry; Orchinik, Leah J; Minich, Nori; Dietrich, Ann; Nuss, Kathryn; Wright, Martha; Bangert, Barbara; Rusin, Jerome; Yeates, Keith Owen

2015-01-01

To investigate the effects of mild traumatic brain injury (mTBI) in children on symptom ratings of behavior problems across the first-year postinjury. Emergency departments of 2 regional children's hospitals. Parents of 176 children with mTBI and 90 children with orthopedic injury aged 8 to 15 years. Group comparisons of postinjury parent and teacher ratings of child behavior problems controlling for background factors. Child Behavior Checklist and Teacher's Report Form. For younger but not older children in the sample, children with mTBI compared with children with orthopedic injury had higher postinjury ratings on the Child Behavior Checklist Total Behavior Problem scale (t264 = 3.34, P < .001) and higher rates of T-scores of 60 or more on this scale (odds ratio = 3.00; 95% confidence interval, 1.33-6.77; P = .008). For children with mTBI, hospitalization, motor vehicle accidents, loss of consciousness, and magnetic resonance imaging abnormality were associated with higher parent or teacher ratings. School-aged children with mTBI are at risk for persistent symptoms of behavior problems, especially if mTBI is more severe or occurs at a younger age. The findings justify monitoring of behavior long after injury and further research to identify risk factors for these symptoms and their association with clinical disorders.

[CHARACTERISTICS OF COMBINED ANESTHESIA WITH EPIDURAL COMPONENTE DEPENDING ON VEGETATIVE NERVOUS SYSTEM TYPE].

PubMed

Hasanov, F J; Aslanov, A A; Muradov, N F; Namazova, K N

2016-01-01

The research objective was to study the characteristics of combined anesthesia with epidural componente (CAEC) depending on vegetative nervous system type (VNS) in patients who underwent large scale traumatic surgical operations on abdominal cavity organs. The scientific research was conducted in Anaesthesiology--Reanimation Department of the Scientific Surgical Centre named after acad. MA. Topchubashev, the Ministry of Health of the Azerbaijan Republic. The research objects were 69 patients who underwent operations in conditions of CAEC due to different serious surgical pathologies of abdominal cavity organs. VNS type was identified based on electroencephalogram, Cerdo Vegetative Index (CVI), Hildebrandt coefficient (HC) and single neurophysiological tests. The patients were divided into three groups depending on VNS type: I--normotonics--17 patients (24.7%), II--sympathatonics--25 patients (36.2%), and III--vagotonics--27 patients (39.1%). Blood adrenocorticotropic hormone (ACTH) and cortisol concentration were studied in 3 stages: I -preoperative, II--operation traumatic stage, III--the 1st postoperative days. The other indicators (heart rate, systolic blood pressure--SBP, dyastolic blood pressure--DBR average blood pressure--BP ave., pulse oximetry SpO₂, ECG, gases in blood and acid-base balance, electrolytes, blood glucose level, myocardium oxygen demand--MOD) were registered after 20 minutes and the 2nd day after operation besides the above stages. The research results indicated that it is possible to define the vegetative nervous system type superiority based on complex of single tests data, EEG, ECG, Cerdo Vegetative Index, Hildebrandt coefficient. CAEC can be considered optimun alternative of general anesthesia ensuring neurohumoral and hemodynamic stability in large scale, traumatic operations on abdominal cavity organs. Clinical course of CAEC is characterized by firmer hemodynamic and humoral stability in patients with functional balance of sympathetic and parasympathetic divisions of vegetative nervous system, that is in normotonics in comparison with sympathico-, and parasympathotonics.

Identifying Dental Anxiety in Children's Drawings and correlating It with Frankl's Behavior Rating Scale.

PubMed

Mathur, Jyoti; Diwanji, Amish; Sarvaiya, Bhumi; Sharma, Dipal

2017-01-01

To develop a simple method to assess the level of anxiety by using children's drawings and correlating them with Frankl's behavior rating scale. A total of 178 patients aged of 3 to 14 years were handed out two-page forms which contained three sections on coloring and drawing, along with general information, and Frankl's behavior rating scale for the visit. The three types of drawing exercises given to the patients were geometric copy drawings, coloring a nonthreatening figure, and an empty sheet for freehand drawing. Out of 178 patients, 60 showed definitely positive behavior, 73 exhibited positive behavior, 37 showed negative behavior, and 8 were definitely negative on Frankl's behavior rating scale; 133 children had none or, 1 stress marker and 45 exhibited 2 or 3 stress markers in their drawings. Chi-square (χ 2 ) analysis was done with a 2 × 2 contingency table. Observed χ 2 value was 46.166, which at 1 degree of freedom was much greater than that at 0.995 percentile. Therefore, the result was highly significant. Children requiring specialized behavioral techniques can be identified by the presence of stress markers in their drawings. This nonverbal activity by itself can have an overall positive effect on the behavior displayed in the dental clinic. Mathur J, Diwanji A, Sarvaiya B, Sharma D. Identifying Dental Anxiety in Children's Drawings and correlating It with Frankl's Behavior Rating Scale. Int J Clin Pediatr Dent 2017;10(1):24-28.

Cultural Influences on Ratings of Behavioral and Emotional Problems, and School Adjustment for Korean, Korean American, and Caucasian American Children.

ERIC Educational Resources Information Center

Jung, Woo Sik

This study investigated the effects of child behavioral ratings on the Behavioral Assessment System for Children (BASC) assessed for elementary-age students residing in Oklahoma, Los Angeles, and Seoul, Korea. The students completed the BASC Self Report of Personality (SRP) to examine the differences in the self-report ratings of behavioral…

Examining the Relationship between Heart Rate and Problem Behavior: A Case Study of Severe Skin Picking in Prader-Willi Syndrome

ERIC Educational Resources Information Center

Hall, Scott S.; Hammond, Jennifer L.; Hustyi, Kristin M.

2013-01-01

Few studies have examined the relationship between heart rate and self-injurious behavior (SIB) shown by individuals with IDD (intellectual and developmental disabilities). In this single-case study, we simultaneously monitored heart rate and activity levels during a functional analysis of severe skin picking behavior exhibited by a young man with…

Factors Influencing Female Caregivers' Appraisals of Their Preschoolers' Behaviors.

PubMed

Coke, Sallie P; Moore, Leslie C

This study used the Resiliency Model of Family Stress, Adjustment, and Adaptation to explore family factors associated with primary female caregivers' appraisals of children's behaviors, distortion of their appraisals, and children's risk of having behavioral problems. A cross-sectional, correlational design was used. Data were collected from female caregivers of preschoolers. Instruments measured demographic characteristics, comfort in parenting, appraisal of behaviors, daily and parenting stress, depressive symptoms, social support, ratings of children's behaviors, and distortion in ratings. Analyses included χ 2 and simultaneous linear regression. Greater parenting discomfort and daily stress were associated with lower appraisals of children's behaviors. Caucasian race and higher distortion in behavioral ratings were associated with higher risk of behavioral problems. Caregiver's appraisal was associated with daily stress level and parenting comfort. Additional research is needed regarding how these factors affect children's behavior and causes of distorted parental views of children's behaviors. Copyright © 2016 National Association of Pediatric Nurse Practitioners. Published by Elsevier Inc. All rights reserved.

Enhanced broadband absorption in nanowire arrays with integrated Bragg reflectors

NASA Astrophysics Data System (ADS)

Aghaeipour, Mahtab; Pettersson, Håkan

2018-05-01

A near-unity unselective absorption spectrum is desirable for high-performance photovoltaics. Nanowire (NW) arrays are promising candidates for efficient solar cells due to nanophotonic absorption resonances in the solar spectrum. The absorption spectra, however, display undesired dips between the resonance peaks. To achieve improved unselective broadband absorption, we propose to enclose distributed Bragg reflectors (DBRs) in the bottom and top parts of indium phosphide (InP) NWs, respectively. We theoretically show that by enclosing only two periods of In0.56Ga0.44As/InP DBRs, an unselective 78% absorption efficiency (72% for NWs without DBRs) is obtained at normal incidence in the spectral range from 300 nm to 920 nm. Under oblique light incidence, the absorption efficiency is enhanced up to about 85% at an incidence angle of 50°. By increasing the number of DBR periods from two to five, the absorption efficiency is further enhanced up to 95% at normal incidence. In this work, we calculated optical spectra for InP NWs, but the results are expected to be valid for other direct band gap III-V semiconductor materials. We believe that our proposed idea of integrating DBRs in NWs offers great potential for high-performance photovoltaic applications.

An Overview of Communications Technology and Development Efforts for 2015 SBIR Phase I

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Steele, Gynelle C.

2017-01-01

This report highlights innovative SBIR 2015 Phase I projects specifically addressing areas in Communications Technology and Development which is one of six core competencies at NASA Glenn Research Center. There are fifteen technologies featured with emphasis on a wide spectrum of applications such as novel solid state lasers for space-based water vapor dial; wide temperature, high voltage and energy density capacitors for aerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser for methane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites; a SIC-based microcontroller for high-temperature in-situ instruments and systems; improved yield, performance and reliability of high-actuator-count deformable mirrors; embedded multifunctional optical sensor system; switching electronics for space-based telescopes with advanced AO systems; integrated miniature DBR laser module for Lidar instruments; and much more. Each article in this booklet describes an innovation, technical objective, and highlights NASA commercial and industrial applications. space-based water vapor dial; wide temperature, high voltage and energy density capacitors foraerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser formethane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites.

Advances in 750 nm VECSELs (Conference Presentation)

NASA Astrophysics Data System (ADS)

Saarinen, Esa J.; Ranta, Sanna; Lyytikäinen, Jari; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Guina, Mircea

2017-03-01

Lasers operating in the transmission window of tissue at wavelengths between 700 and 800 nm are needed in numerous medical and biomedical applications, including photodynamic therapy and fluorescence microscopy. However, the performance of diode lasers in this spectral range is limited by the lack of appropriate compound semiconductors. Here, we review our recent research on 750 nm VECSELs. Two approaches to reaching the 750 nm wavelength will be discussed. The first approach relies on intra-cavity frequency doubling a wafer-fused 1500 nm VECSEL. The VECSEL gain chip comprises a GaAs-based DBR and an InP-based gain section, which allows for optical pumping with low-cost commercial diodes at 980 nm. With this scheme we have achieved watt-level output powers and tuning of the laser wavelength over a 40 nm band at around 750 nm. The second approach is direct emission at 750 nm using the AlGaAs/GaAs material system. In this approach visible wavelengths are required for optical pumping. However, the consequent higher costs compared to pumping at 980 nm are mitigated by the more compact laser setup and prospects of doubling the frequency to the ultraviolet range.

Multiple-wavelength vertical cavity laser arrays with wide wavelength span and high uniformity

NASA Astrophysics Data System (ADS)

Yuen, Wupen; Li, Gabriel S.; Chang-Hasnain, Connie J.

1996-12-01

Vertical-cavity surface-emitting lasers (VCSELs) are promising for numerous applications. In particular, due to their inherent single Fabry-Perot mode operation, VCSELs can be very useful for wavelength division multiplexing (WDM) systems allowing high bandwidth and high functionalities.1, 2 Multiple wavelength VCSEL arrays with wide channel spacings (>10 nm) provide an inexpensive solution to increasing the capacity of local area networks without using active wavelength controls.1 The lasing wavelength of a VCSEL is determined by the equivalent laser cavity thickness which can be varied by changing the thickness of either the l-spacer or the distributed Bragg reflector (DBR) layers. To make monolithic multiple-wavelength VCSEL arrays, the lasing wavelength, and therefore the cavity thickness, has to be varied at reasonable physical distances. For all practical applications, it is imperative for the fabrication technology to be controllable, cost-effective, and wafer-scale. Recently, we demonstrated a patterned-substrate molecular beam epitaxy (MBE) growth technique with in-situ laser reflectometry monitoring for fabricating multiple wavelength VCSEL arrays.3, 4 With this method, VCSEL arrays with very large and highly controllable lasing wavelength spans and excellent lasing characteristics have been achieved.

Industry Television Ratings for Violence, Sex, and Substance Use

PubMed Central

Gabrielli, Joy; Traore, Aminata; Stoolmiller, Mike; Bergamini, Elaina

2016-01-01

OBJECTIVE: To examine whether the industry-run television (TV) Parental Guidelines discriminate on violence, sexual behavior, alcohol use, and smoking in TV shows, to assess their usefulness for parents. METHODS: Seventeen TV shows (323 episodes and 9214 episode minutes) across several TV show rating categories (TVY7, TVPG, TV14, and TVMA) were evaluated. We content-coded the episodes, recording seconds of each risk behavior, and we rated the salience of violence in each one. Multilevel models were used to test for associations between TV rating categories and prevalence of risk behaviors across and within episodes or salience of violence. RESULTS: Every show had at least 1 risk behavior. Violence was pervasive, occurring in 70% of episodes overall and for 2.3 seconds per episode minute. Alcohol was also common (58% of shows, 2.3 seconds per minute), followed by sex (53% of episodes, 0.26 seconds per minute), and smoking (31% of shows, 0.54 seconds per minute). TV Parental Guidelines did not discriminate prevalence estimates of TV episode violence. Although TV-Y7 shows had significantly less substance use, other categories were poor at discriminating substance use, which was as common in TV-14 as TV-MA shows. Sex and gory violence were the only behaviors demonstrating a graded increase in prevalence and salience for older-child rating categories. CONCLUSIONS: TV Parental Guidelines ratings were ineffective in discriminating shows for 3 out of 4 behaviors studied. Even in shows rated for children as young as 7 years, violence was prevalent, prominent, and salient. TV ratings were most effective for identification of sexual behavior and gory violence. PMID:27550985

[Autoaggression and pulse rate--a longitudinal study].

PubMed

Rohmann, U H; Elbing, U; Hartmann, H

1988-12-01

This article presents a model of autoaggressive behavior in which a distinction is made between determining and maintaining factors. Specific environmental, in particular social, and organismic variables are linked to them. The two types of variables interact, thus causing or maintaining autoaggressive behavior. A theory of autoaggression must therefore rely on multicausal/multimodal explanations. A connection between autoaggression and a high level of arousal suggests itself. In this single-case longitudinal study a comparison was made between heart rate and frequency of autoaggressive behavior. High heart rates were found to be correlated with low frequencies of autoaggressive behavior and vice versa. Decreasing autoaggressive behavior was coupled with increasing muscle relaxation and increasing motor activity. However, abnormally high heart rates were associated with both low and high levels of motor activity.

Validity and reliability of the Behavior Problems Inventory, the Aberrant Behavior Checklist, and the Repetitive Behavior Scale-Revised among infants and toddlers at risk for intellectual or developmental disabilities: a multi-method assessment approach.

PubMed

Rojahn, Johannes; Schroeder, Stephen R; Mayo-Ortega, Liliana; Oyama-Ganiko, Rosao; LeBlanc, Judith; Marquis, Janet; Berke, Elizabeth

2013-05-01

Reliable and valid assessment of aberrant behaviors is essential in empirically verifying prevention and intervention for individuals with intellectual or developmental disabilities (IDD). Few instruments exist which assess behavior problems in infants. The current longitudinal study examined the performance of three behavior-rating scales for individuals with IDD that have been proven psychometrically sound in older populations: the Aberrant Behavior Checklist (ABC), the Behavior Problems Inventory (BPI-01), and the Repetitive Behavior Scale - Revised (RBS-R). Data were analyzed for 180 between six and 36 months old children at risk for IDD. Internal consistency (Cronbach's α) across the subscales of the three instruments was variable. Test-retest reliability of the three BPI-01 subscales ranged from .68 to .77 for frequency ratings and from .65 to .80 for severity ratings (intraclass correlation coefficients). Using a multitrait-multimethod matrix approach high levels of convergent and discriminant validity across the three instruments was found. As anticipated, there was considerable overlap in the information produced by the three instruments; however, each behavior-rating instrument also contributed unique information. Our findings support using all three scales in conjunction if possible. Copyright © 2013 Elsevier Ltd. All rights reserved.

How Do Observational Scales Correlate the Ratings of Children's Behavior during Pediatric Procedural Sedation?

PubMed Central

Moura, Larissa da Silva

2016-01-01

Background. There is little information regarding the ability of observational scales to properly assess children's behavior during procedural sedation. Aim. To evaluate the characteristics of the Houpt scales, the Ohio State University Behavioral Rating Scale (OSUBRS) and the Venham Behavior Rating Scale when applied to preschool children undergoing conscious dental sedation. Design. This study included 27 children, 4–6 years old with early childhood caries that participated in a clinical trial (NCT02284204) that investigated two sedative regimes using oral midazolam/ketamine. Dental appointments were video-recorded; five calibrated observers assessed 1,209 minutes of video recording to score the children's behavior, following the instructions of the investigated scales. Data were analyzed by descriptive analysis and Spearman correlation tests (P < 0.05). Results. The Houpt overall behavior and the Venham scale were highly correlated (rho = −0.87; P < 0.001). OSUBRS scores were better correlated with Houpt overall behavior and Venham ratings, when compared to Houpt scores in the categories for movement and crying. Conclusions. The Houpt overall behavior and the Venham scores are global scales that properly measure children's behavior during dental sedation. Continuous assessment with OSUBRS through videos has a chance to give more precise data, while the Houpt categories can easily demonstrate children's behavior during procedures. PMID:28116299

When does transformational leadership enhance employee proactive behavior? The role of autonomy and role breadth self-efficacy.

PubMed

Den Hartog, Deanne N; Belschak, Frank D

2012-01-01

Two multisource studies address the interactive effects of personal and contextual variables on employees' proactive behavior. In line with previous work, we find positive main effects of transformational leadership, role breadth self-efficacy, and job autonomy on employee proactive behavior (personal initiative in Study 1 and prosocial proactive behavior in Study 2). As expected, a 3-way interaction qualifies these main effects: In situations of high autonomy, transformational leadership relates positively to proactive behavior for individuals high (but not low) on self-efficacy. Vice versa, in situations low on job autonomy, transformational leadership relates positively to proactive behavior for individuals low (but not high) on self-efficacy. This pattern is found both for self-ratings and peer-ratings of employees' proactive behavior in Study 1 and for supervisor ratings of such behavior in Study 2.

The relation between stressful life events and adjustment in elementary school children: the role of social support and social problem-solving skills.

PubMed

Dubow, E F; Tisak, J

1989-12-01

This study investigated the relation between stressful life events and adjustment in elementary school children, with particular emphasis on the potential main and stress-buffering effects of social support and social problem-solving skills. Third through fifth graders (N = 361) completed social support and social problem-solving measures. Their parents provided ratings of stress in the child's environment and ratings of the child's behavioral adjustment. Teachers provided ratings of the children's behavioral and academic adjustment. Hierarchical multiple regressions revealed significant stress-buffering effects for social support and problem-solving skills on teacher-rated behavior problems, that is, higher levels of social support and problem-solving skills moderated the relation between stressful life events and behavior problems. A similar stress-buffering effect was found for problem-solving skills on grade-point average and parent-rated behavior problems. In terms of children's competent behaviors, analyses supported a main effect model of social support and problem-solving. Possible processes accounting for the main and stress-buffering effects are discussed.

Development of a Behaviorally Anchored Rating Scale for Leadership

DTIC Science & Technology

2018-01-01

Research Product 2018-06 Development of a Behaviorally Anchored Rating Scale for Leadership Tatiana H. Toumbeva Krista L...anchored Rating Scale for Leadership 5a. CONTRACT NUMBER W5J9CQ-11-D-0004 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62278 6...observer- based behavioral measure to help instructors more reliably and accurately evaluate the development of leadership attributes and competencies

Test Review: Michael H. Epstein and Lori Synhorst "Preschool Behavioral and Emotional Rating Scale" Austin, TX--PRO-ED, 2009

ERIC Educational Resources Information Center

Drevon, Daniel D.

2011-01-01

This article presents a review of the "Preschool Behavioral and Emotional Rating Scale" (PreBERS), a 42-item family member--or school personnel--completed rating scale designed to measure the behavioral and emotional strengths of preschool children ages 3-0 to 5-11. According to the manual, results can be used to identify preschoolers with limited…

A Technique for Tracking the Reading Rate to Identify the E-Book Reading Behaviors and Comprehension Outcomes of Elementary School Students

ERIC Educational Resources Information Center

Huang, Yueh-Min; Liang, Tsung-Ho

2015-01-01

Tracking individual reading behaviors is a difficult task, as is carrying out real-time recording and analysis throughout the reading process, but these aims are worth pursuing. In this study, the reading rate is adopted as an indicator to identify different reading behaviors and comprehension outcomes. A reading rate tracking technique is thus…

Stimulus-reinforcer relations established during training determine resistance to extinction and relapse via reinstatement.

PubMed

Bai, John Y H; Jonas Chan, C K; Elliffe, Douglas; Podlesnik, Christopher A

2016-11-01

The baseline rate of a reinforced target response decreases with the availability of response-independent sources of alternative reinforcement; however, resistance to disruption and relapse increases. Because many behavioral treatments for problem behavior include response-dependent reinforcement of alternative behavior, the present study assessed whether response-dependent alternative reinforcement also decreases baseline response rates but increases resistance to extinction and relapse. We reinforced target responding at equal rates across two components of a multiple schedule with pigeons. We compared resistance to extinction and relapse via reinstatement of (1) a target response trained concurrently with a reinforced alternative response in one component with (2) a target response trained either concurrently or in separate components from the alternative response across conditions. Target response rates trained alone in baseline were higher but resistance to extinction and relapse via reinstatement tests were greater after training concurrently with the alternative response. In another assessment, training target and alternative responding together, but separating them during extinction and reinstatement tests, produced equal resistance to extinction and relapse. Together, these findings are consistent with behavioral momentum theory-operant response-reinforcer relations determined baseline response rates but Pavlovian stimulus-reinforcer relations established during training determined resistance to extinction and relapse. These findings imply that reinforcing alternative behavior to treat problem behavior could initially reduce rates but increase persistence. © 2016 Society for the Experimental Analysis of Behavior.

SELECTION DYNAMICS IN JOINT MATCHING TO RATE AND MAGNITUDE OF REINFORCEMENT

PubMed Central

McDowell, J. J; Popa, Andrei; Calvin, Nicholas T

2012-01-01

Virtual organisms animated by a selectionist theory of behavior dynamics worked on concurrent random interval schedules where both the rate and magnitude of reinforcement were varied. The selectionist theory consists of a set of simple rules of selection, recombination, and mutation that act on a population of potential behaviors by means of a genetic algorithm. An extension of the power function matching equation, which expresses behavior allocation as a joint function of exponentiated reinforcement rate and reinforcer magnitude ratios, was fitted to the virtual organisms' data, and over a range of moderate mutation rates was found to provide an excellent description of their behavior without residual trends. The mean exponents in this range of mutation rates were 0.83 for the reinforcement rate ratio and 0.68 for the reinforcer magnitude ratio, which are values that are comparable to those obtained in experiments with live organisms. These findings add to the evidence supporting the selectionist theory, which asserts that the world of behavior we observe and measure is created by evolutionary dynamics. PMID:23008523

Do people agree about the causes of behavior? A social relations analysis of behavior ratings and causal attributions.

PubMed

Robins, Richard W; Mendelsohn, Gerald A; Connell, Joanie B; Kwan, Virginia S Y

2004-02-01

Two studies examined consistency and agreement in behavior ratings and causal attributions. In Study 1, participants (N = 280) engaged in a series of getting-acquainted conversations in one of 3 communication media (face-to-face, telephone, computer mediated); in Study 2, participants (N = 120) engaged in a competitive group task. In both studies, participants rated themselves and their interaction partners on a set of behaviors and then made attributions about the causes of those behaviors. The major findings were that (a) participants consistently favored some causal factors over others in explaining both their own and their partners' behavior, supporting the existence of generalized attributional styles; and (b) participants showed moderate self-partner and partner-partner agreement about behavior but virtually no agreement about the causes of behavior. Thus, in brief interactions people tend to see themselves and others through the lens of their stable patterns of perceiving and interpreting behavior.

Leadership behavior changes following a theory-based leadership development intervention: A longitudinal study of subordinates' and leaders' evaluations.

PubMed

Larsson, Gerry; Sandahl, Christer; Söderhjelm, Teresa; Sjövold, Endre; Zander, Ann

2017-02-01

The aim was to evaluate effects of leadership courses based on the developmental leadership model at the leadership behavioral level. A longitudinal design was employed with assessments before, one and six months after the leadership courses. The sample consisted of 59 leaders who made self-ratings and were rated by at least three subordinates on each occasion. Leadership behaviors were measured with the Developmental Leadership Questionnaire (DLQ). A limited increase of favorable leadership behaviors and a significant reduction of unfavorable leadership behaviors were found, particularly according to the subordinates' ratings. A cluster analysis yielded three meaningful leader profiles and showed that this pattern was found in all three profiles, irrespective of how favorably they were rated before the onset of the intervention. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Behavior related pauses in simple spike activity of mouse Purkinje cells are linked to spike rate modulation

PubMed Central

Cao, Ying; Maran, Selva K.; Dhamala, Mukesh; Jaeger, Dieter; Heck, Detlef H.

2012-01-01

Purkinje cells (PCs) in the mammalian cerebellum express high frequency spontaneous activity with average spike rates between 30 and 200 Hz. Cerebellar nuclear (CN) neurons receive converging input from many PCs resulting in a continuous barrage of inhibitory inputs. It has been hypothesized that pauses in PC activity trigger increases in CN spiking activity. A prediction derived from this hypothesis is that pauses in PC simple spike activity represent relevant behavioral or sensory events. Here we asked whether pauses in the simple spike activity of PCs related to either fluid licking or respiration, play a special role in representing information about behavior. Both behaviors are widely represented in cerebellar PC simple spike activity. We recorded PC activity in the vermis and lobus simplex of head fixed mice while monitoring licking and respiratory behavior. Using cross correlation and Granger causality analysis we examined whether short ISIs had a different temporal relation to behavior than long ISIs or pauses. Behavior related simple spike pauses occurred during low-rate simple spike activity in both licking and breathing related PCs. Granger causality analysis revealed causal relationships between simple spike pauses and behavior. However, the same results were obtained from an analysis of surrogate spike trains with gamma ISI distributions constructed to match rate modulations of behavior related Purkinje cells. Our results therefore suggest that the occurrence of pauses in simple spike activity does not represent additional information about behavioral or sensory events that goes beyond the simple spike rate modulations. PMID:22723707

Online exclusive: behavioral adjustment of children and adolescents with cancer: teacher, parent, and self-report.

PubMed

Moore, Ida M; Challinor, Julia; Pasvogel, Alice; Matthay, Katherine; Hutter, John; Kaemingk, Kris

2003-01-01

To describe behavioral adjustment in children and adolescents with acute lymphoblastic leukemia (ALL) and to determine whether behavioral adjustment is correlated with cognitive and academic abilities. Descriptive, cross-sectional design. Two pediatric oncology treatment centers. 47 children and adolescents who had been receiving ALL therapy for at least one year or who were off therapy for no more than three years and their parents and teachers. Wechsler Intelligence Scale for Children-Revised (WISC-R) and Wide Range Achievement Test-Revised (WRAT-R) data were available on a subset of 17 subjects. Parent, teacher, and self-report Behavioral Assessment System for Children (BASC) ratings were used to measure behavioral adjustment. WISC-R measured cognitive abilities, and WRAT-R measured academic abilities. Demographic, family, and treatment-related data also were collected. Behavioral adjustment and cognitive and academic abilities. At least 20% of teacher ratings for somatization, learning problems, leadership, and study skills; parent ratings for somatization, adaptability, attention problems, withdrawal, anxiety, social skills, and depression; and self-report ratings for anxiety and attitude to school were in the at-risk range (i.e., presence of significant problems that require treatment). The majority of teacher BASC ratings were correlated significantly with WISC-R and WRAT-R scores. Self-report depression and social stress ratings were correlated significantly with some WISC-R and WRAT-R scores. Treatment-related experiences such as body image alterations and mental and emotional problems were associated with problematic behaviors, including depression, somatization, withdrawal, and social stress. Youth with ALL are at risk for some behavioral adjustment problems, particularly anxiety, somatization, adaptability, attention, and withdrawal. Cognitive and academic abilities are associated with some dimensions of behavioral adjustment. Findings suggest the need for ongoing assessment of behavioral adjustment and cognitive and academic abilities of children with ALL. Behavioral interventions that target at-risk mannerisms, such as somatization, depression, anxiety, and social stress, are needed. Central nervous system treatment may contribute to behavioral adjustment problems, as well as to cognitive and academic problems. Strategies to improve academic abilities also may have a positive effect on behavioral adjustment.

Risky driving and sexual behaviors as developmental outcomes of co-occurring substance use and antisocial behavior.

PubMed

Luk, Jeremy W; Worley, Matthew J; Winiger, Evan; Trim, Ryan S; Hopfer, Christian J; Hewitt, John K; Brown, Sandra A; Wall, Tamara L

2016-12-01

To examine the associations between substance use and antisocial behavior trajectories and seven risky behaviors over time. Data were collected from a high-risk sample of adolescents followed into young adulthood. Five trajectory classes, identified based on dual development of substance use and antisocial behavior symptoms, were used to predict three risky driving and four risky sexual behaviors. In this high-risk sample (n=530), participants reported notably high overall rates of reckless driving (55.5%) and unprotected sex under the influence (44.8%) in the past year. Risky behaviors that are typically of low base rates in population-based studies were also elevated, with 8.8% reporting past-year driving under the influence (DUI) charge, 17.6% reporting lifetime sexually transmitted infection (STI), and 10.4% reporting lifetime injection drug use. The Dual Chronic class had the highest levels of all seven risky behaviors, and were 3-4 times more likely to report risky driving, lifetime STI, and injection drug use than the Relatively Resolved class. Rates of past-year reckless driving and DUI were elevated among classes with persistent antisocial behavior, whereas rates of DUI, DUI charge, and unprotected sex under the influence were elevated among classes with persistent substance use. Young adults with persistent co-occurring substance use and antisocial behavior engage in multiple very costly risky behaviors. Differential associations between risky behaviors and trajectory classes highlight the need for targeted interventions. Published by Elsevier Ireland Ltd.

[Verification of the double dissociation model of shyness using the implicit association test].

PubMed

Fujii, Tsutomu; Aikawa, Atsushi

2013-12-01

The "double dissociation model" of shyness proposed by Asendorpf, Banse, and Mtücke (2002) was demonstrated in Japan by Aikawa and Fujii (2011). However, the generalizability of the double dissociation model of shyness was uncertain. The present study examined whether the results reported in Aikawa and Fujii (2011) would be replicated. In Study 1, college students (n = 91) completed explicit self-ratings of shyness and other personality scales. In Study 2, forty-eight participants completed IAT (Implicit Association Test) for shyness, and their friends (n = 141) rated those participants on various personality scales. The results revealed that only the explicit self-concept ratings predicted other-rated low praise-seeking behavior, sociable behavior and high rejection-avoidance behavior (controlled shy behavior). Only the implicit self-concept measured by the shyness IAT predicted other-rated high interpersonal tension (spontaneous shy behavior). The results of this study are similar to the findings of the previous research, which supports generalizability of the double dissociation model of shyness.

Industry Television Ratings for Violence, Sex, and Substance Use.

PubMed

Gabrielli, Joy; Traore, Aminata; Stoolmiller, Mike; Bergamini, Elaina; Sargent, James D

2016-09-01

To examine whether the industry-run television (TV) Parental Guidelines discriminate on violence, sexual behavior, alcohol use, and smoking in TV shows, to assess their usefulness for parents. Seventeen TV shows (323 episodes and 9214 episode minutes) across several TV show rating categories (TVY7, TVPG, TV14, and TVMA) were evaluated. We content-coded the episodes, recording seconds of each risk behavior, and we rated the salience of violence in each one. Multilevel models were used to test for associations between TV rating categories and prevalence of risk behaviors across and within episodes or salience of violence. Every show had at least 1 risk behavior. Violence was pervasive, occurring in 70% of episodes overall and for 2.3 seconds per episode minute. Alcohol was also common (58% of shows, 2.3 seconds per minute), followed by sex (53% of episodes, 0.26 seconds per minute), and smoking (31% of shows, 0.54 seconds per minute). TV Parental Guidelines did not discriminate prevalence estimates of TV episode violence. Although TV-Y7 shows had significantly less substance use, other categories were poor at discriminating substance use, which was as common in TV-14 as TV-MA shows. Sex and gory violence were the only behaviors demonstrating a graded increase in prevalence and salience for older-child rating categories. TV Parental Guidelines ratings were ineffective in discriminating shows for 3 out of 4 behaviors studied. Even in shows rated for children as young as 7 years, violence was prevalent, prominent, and salient. TV ratings were most effective for identification of sexual behavior and gory violence. Copyright © 2016 by the American Academy of Pediatrics.

The diagnostic utility of behavioral checklists in identifying children with ADHD and children with working memory deficits.

PubMed

Alloway, Tracy Packiam; Gathercole, Susan E; Holmes, Joni; Place, Maurice; Elliott, Julian G; Hilton, Kerry

2009-09-01

The present study investigated whether children with ADHD and those with working memory impairments have a common behavioral profile in the classroom. Three teacher checklists were used: the Conners' teacher rating scale (CTRS), the behavior rating inventory of executive function (BRIEF), and the working memory rating scale. The Conners' continuous performance test (CPT) was also included to determine whether there is a correspondence between performance on this widely used cognitive measure of attention deficits and teacher ratings of classroom behavior. All three behavior scales, but not the CPT, were able to successfully discriminate children with ADHD and those with working memory deficits from typically-developing children. Both the CTRS and the BRIEF discriminated a significant proportion of the children with ADHD from those with working memory deficits, indicating that while both groups exhibit behavioral problems in the classroom, they are characterized by differential attention profiles. The children with ADHD were identified on the basis of oppositional and hyperactive behavior, while those with working memory deficits were more inattentive.

Effects of behavioral and pharmacological therapies on peer reinforcement of deviancy in children with ADHD-only, ADHD and conduct problems, and controls

PubMed Central

Helseth, Sarah A.; Waschbusch, Daniel A.; Gnagy, Elizabeth M.; Onyango, Adia N.; Burrows-MacLean, Lisa; Fabiano, Gregory A.; Coles, Erika K.; Chacko, Anil; Wymbs, Brian T.; Walker, Kathryn S.; Wymbs, Frances A.; Garefino, Allison; Massetti, Greta M.; Mazzant, Jessica Robb; Hoffman, Martin T.; Waxmonsky, James G.; Nichols-Lopez, Kristin; Pelham, William E.

2015-01-01

Objective This study compared the unique and combined effects of evidence-based treatments for ADHD —stimulant medication and behavior modification—on children’s rates of reinforcement for deviant peer behavior (RDPB). Method Using a within-subjects design, 222 elementary school-age children attending a summer treatment program, including 151 children with ADHD (127 male), with and without comorbid conduct problems, and 71 control children (57 male), received varying combinations of behavior modification (no, low-intensity, and high-intensity) and methylphenidate (placebo, 0.15 mg/kg, 0.30 mg/kg, and 0.60 mg/kg). RDPB was measured through direct observation and compared across all behavior modification and medication conditions. Results Children with ADHD reinforced the deviant behavior of their peers at a significantly higher rate than control children in the absence of either intervention. However, that difference largely disappeared in the presence of both behavior modification and medication. Both low and high-intensity behavior modification, as well as medium (0.30 mg/kg) and high (0.60 mg/kg) doses of methylphenidate, significantly reduced the rate of ADHD children’s RDPB to levels similar to the control group. Conclusions Results indicate that although untreated children with ADHD do engage in RDPB at a greater rate than their non-ADHD peers, existing evidence-based interventions can substantially decrease the presence of RDPB, thereby limiting potential iatrogenic effects in group-based treatment settings. Public Health Significance Statement This study found that children with behavior disorders reinforced their peers' deviant behaviors much more than typically developing children. However, behavior modification and medication treatments both reduced reinforcement rates, indicating that peer contagion can easily be managed in group-based treatments for children PMID:25495357

Predictors of discrepancies between fathers and mothers in rating behaviors of preschool children with and without ADHD.

PubMed

van der Veen-Mulders, Lianne; Nauta, Maaike H; Timmerman, Marieke E; van den Hoofdakker, Barbara J; Hoekstra, Pieter J

2017-03-01

To examine child factors and parental characteristics as predictors of discrepancies between parents' ratings of externalizing and internalizing behavior problems in a sample of preschool children with ADHD and behavior problems and in a nonclinical sample. We investigated correspondence and discrepancies between parents' ratings on the externalizing and internalizing behavior problems broadband scales of the Child Behavior Checklist version for preschool children (CBCL/1.5-5). Parents of 152 preschool children, with ADHD and behavior problems (n = 72) and nonclinical children (n = 80), aged between 28 and 72 months (M = 47.26, SD = 12.7), completed the CBCL/1.5-5. Candidate predictors of discrepancy included the child's age and sex, and parents' levels of parenting stress, depressive mood, attention-deficit and disruptive behavior. Hierarchical multiple regression analyses were conducted. Correspondence between parents, both for ratings on internalizing and externalizing behavior problems, was high (r = .63-.77). In the clinical sample, mothers rated the severity of externalizing behavior problems significantly higher than did fathers (p = < .001). Discrepancy between fathers and mothers on externalizing behavior problems was not predicted by child factors or interparental differences in psychopathology, but it was predicted by interparental differences in parenting stress (R 2  = .25, p < .001). This effect was significantly larger in the nonclinical sample (ΔR 2  = .06, p < .001). When parents disagree on the severity level of preschool children's externalizing behavior problems, the clinician should take into consideration that differences in parenting stress might be involved.

Effects of Task Size on Work-Related and Aberrant Behaviors of Youths with Autism and Mental Retardation.

ERIC Educational Resources Information Center

Sweeney, Holly Morsbach; LeBlanc, Judith M.

1995-01-01

This study analyzed effects of repetitive task size on rate of responding and behavior of five adolescents with autism and mental retardation. Compared to large-task conditions, small-task conditions resulted in higher on-task behavior and better work-related behavior for all participants and higher work rate for four participants. (Author/PB)

Results from a Tailored SMS and Behavior-Tracking Pilot Study on Sun-Safe Behaviors in Young Women

ERIC Educational Resources Information Center

Darlow, Susan; Heckman, Carolyn

2017-01-01

Background: The elevated rates of ultraviolet radiation (UVR) exposure and low rates of sun protection in young adult women indicate a need for age- and gender-appropriate interventions that address these behaviors. Aims: To examine the effects of daily behavior tracking and individually tailored text messages on sun protection and UVR exposure…

Safety leadership: application in construction site.

PubMed

Cooper, Dominic

2010-01-01

The extant safety literature suggests that managerial Safety Leadership is vital to the success and maintenance of a behavioral safety process. The current paper explores the role of Managerial Safety Leadership behaviors in the success of a behavioral safety intervention in the Middle-East with 47,000 workers from multiple nationalities employed by fourteen sub-contractors and one main contractor. A quasi-experimental repeating ABABAB, within groups design was used. Measurement focused on managerial Safety Leadership and employee safety behaviors as well as Corrective Actions. Data was collected over 104 weeks. During this time, results show safety behavior improved by 30 percentage points from an average of 65% during baseline to an average of 95%. The site achieved 121 million man-hours free of lost-time injuries on the longest run. Stepwise multiple regression analyses indicated 86% of the variation in employee safety behavior was associated with senior, middle and front-line manager's Safety Leadership behaviors and the Corrective Action Rate. Approximately 38% of the variation in the Total Recordable Incident Rate (TRIR) was associated with the Observation rate, Corrective Action Rate and Observers Records of managerial safety leaders (Visible Ongoing Support). The results strongly suggest manager's Safety Leadership influences the success of Behavioral Safety processes.

Effect of Strengthening Mechanism on Strain-Rate Related Tensile Properties of Low-Carbon Sheet Steels for Automotive Application

NASA Astrophysics Data System (ADS)

Das, Anindya; Biswas, Pinaki; Tarafder, S.; Chakrabarti, D.; Sivaprasad, S.

2018-05-01

In order to ensure crash resistance of the steels used in automotive components, the ensile deformation behavior needs to be studied and predicted not only under quasi-static condition, but also under dynamic loading rates. In the present study, tensile tests have been performed on four different automobile grade sheet steels, namely interstitial free steel, dual-phase 600 and 800, and a carbon manganese steel over the strain rate regime of 0.001-800/s. Apart from the variation in strength (which always increased with strain rate), the effect of strengthening mechanism on strain rate sensitivity and strain hardening behavior has been evaluated. Strain rate sensitivity was found to increase at high-strain rate regime for all the steels. Contribution of solid solution hardening on strain rate sensitivity at lower plastic strains was found to be higher compared to dislocation strengthening and second-phase hardening. However, precipitation hardening coupled with solid solution hardening produced the highest strain rate sensitivity, in C-Mn-440 steel at high strain rates. Different strain-rate-sensitive models which take into account the change in yield stress and strain hardening behavior with strain rate for ductile materials were used to predict the flow behavior of these sheet steels at strain rates up to 800/s.

Reliability and Validity of Prototype Diagnosis for Adolescent Psychopathology.

PubMed

Haggerty, Greg; Zodan, Jennifer; Mehra, Ashwin; Zubair, Ayyan; Ghosh, Krishnendu; Siefert, Caleb J; Sinclair, Samuel J; DeFife, Jared

2016-04-01

The current study investigated the interrater reliability and validity of prototype ratings of 5 common adolescent psychiatric disorders: attention-deficit/hyperactivity disorder, conduct disorder, major depressive disorder, generalized anxiety disorder, and posttraumatic stress disorder. One hundred fifty-seven adolescent inpatient participants consented to participate in this study. We compared ratings from 2 inpatient clinicians, blinded to each other's ratings and patient measures, after their separate initial diagnostic interview to assess interrater reliability. Prototype ratings completed by clinicians after their initial diagnostic interview with adolescent inpatients and outpatients were compared with patient-reported behavior problems and parents' report of their child's behavioral problems. Prototype ratings demonstrated good interrater reliability. Clinicians' prototype ratings showed predicted relationships with patient-reported behavior problems and parent-reported behavior problems. Prototype matching seems to be a possible alternative for psychiatric diagnosis. Prototype ratings showed good interrater reliability based on clinicians unique experiences with the patient (as opposed to video-/audio-recorded material) with no training.

THE HUMAN BEHAVIOR RATING SCALE-BRIEF: A TOOL TO MEASURE 21ST CENTURY SKILLS OF K-12 LEARNERS.

PubMed

Woods-Groves, Suzanne

2015-06-01

Currently there is a call for brief concise measurements to appraise relevant 21st century college readiness skills in K-12 learners. This study employed K-12 teachers' ratings for over 3,000 students for an existing 91-item rating scale, the Human Behavior Rating Scale, that measured the 21st century skills of persistence, curiosity, externalizing affect, internalizing affect, and cognition. Teachers' ratings for K-12 learners were used to develop a brief, concise, and manageable 30-item tool, the Human Behavior Rating Scale-Brief. Results yielded high internal consistency coefficients and inter-item correlations. The items were not biased with regard to student sex or race, and were supported through confirmatory factor analyses. In addition, when teachers' ratings were compared with students' academic and behavioral performance data, moderate to strong relationships were revealed. This study provided an essential first step in the development of a psychometrically sound, manageable, and brief tool to appraise 21st century skills in K-12 learners.

Discrepancies in Parent and Teacher Ratings of Social-Behavioral Functioning of Children with Chromosome 22q11.2 Deletion Syndrome: Implications for Assessment

ERIC Educational Resources Information Center

Shashi, Vandana; Wray, Emily; Schoch, Kelly; Curtiss, Kathleen; Hooper, Stephen R.

2013-01-01

Children with 22q11.2 deletion syndrome exhibit high rates of social-behavioral problems, particularly in the internalizing domain, indicating an area in need of intervention. The current investigation was designed to obtain information regarding parent and teacher ratings of the social-emotional behavior of children with 22q11DS. Using the Child…

The effect of virtual reality during dental treatment on child anxiety and behavior.

PubMed

Sullivan, C; Schneider, P E; Musselman, R J; Dummett, C O; Gardiner, D

2000-01-01

Virtual reality, a three-dimensional computer generated world, has been shown to relax adults during dental treatment. The purpose of this study was to investigate the effect of virtual reality on the behavior and anxiety of children during dental treatment. The behavior, anxiety and heart rate of twenty-six children, ages five to seven years were evaluated for the first five minutes of two restorative treatment visits. Thirteen children viewed virtual reality at their first restorative visit and not the second, and thirteen children viewed virtual reality at the second restorative visit and not the first. Before and immediately following the restorative visits, each child was instructed to draw a human figure. The restorative appointments were video recorded and heart rate monitored. The drawings and videotapes were rated independently by two examiners. The Koppitz method of evaluating drawings was used to measure anxiety. The Frankl behavior rating scale was used to evaluate behavior. Differences (ANOVA) in behavior (p < or = 0.50) and anxiety (p < or = 0.65) were not significant. The overall pulse rate was significantly lower (ANOVA p < or = 0.001) when the child was wearing glasses and viewing virtual reality. In conclusion, virtual reality during dental treatment had no significant effect on the behavior or anxiety but significantly reduced the pulse.

Self-Reported Risk and Delinquent Behavior and Problem Behavioral Intention in Hong Kong Adolescents: The Role of Moral Competence and Spirituality

PubMed Central

Shek, Daniel T. L.; Zhu, Xiaoqin

2018-01-01

Based on the six-wave data collected from Grade 7 to Grade 12 students (N = 3,328 at Wave 1), this pioneer study examined the development of problem behaviors (risk and delinquent behavior and problem behavioral intention) and the predictors (moral competence and spirituality) among adolescents in Hong Kong. Individual growth curve models revealed that while risk and delinquent behavior accelerated and then slowed down in the high school years, adolescent problem behavioral intention slightly accelerated over time. After controlling the background socio-demographic factors, moral competence and spirituality were negatively associated with risk and delinquent behavior as well as problem behavioral intention across all waves as predicted. Regarding the rate of change in the outcome measures, while the initial level of spirituality was positively linked to the growth rate of risk and delinquent behavior, the initial level of moral competence was negatively associated with the growth rate of problem behavioral intention. The theoretical and practical implications of the present findings are discussed with reference to the role of moral competence and spirituality in the development of adolescent problem behavior. PMID:29651269

Self-Reported Risk and Delinquent Behavior and Problem Behavioral Intention in Hong Kong Adolescents: The Role of Moral Competence and Spirituality.

PubMed

Shek, Daniel T L; Zhu, Xiaoqin

2018-01-01

Based on the six-wave data collected from Grade 7 to Grade 12 students ( N = 3,328 at Wave 1), this pioneer study examined the development of problem behaviors (risk and delinquent behavior and problem behavioral intention) and the predictors (moral competence and spirituality) among adolescents in Hong Kong. Individual growth curve models revealed that while risk and delinquent behavior accelerated and then slowed down in the high school years, adolescent problem behavioral intention slightly accelerated over time. After controlling the background socio-demographic factors, moral competence and spirituality were negatively associated with risk and delinquent behavior as well as problem behavioral intention across all waves as predicted. Regarding the rate of change in the outcome measures, while the initial level of spirituality was positively linked to the growth rate of risk and delinquent behavior, the initial level of moral competence was negatively associated with the growth rate of problem behavioral intention. The theoretical and practical implications of the present findings are discussed with reference to the role of moral competence and spirituality in the development of adolescent problem behavior.

The Role Behavioral Adjustment Plays in Placing Middle School Students "At Risk" of Academic Failure.

ERIC Educational Resources Information Center

Flynn, Timothy M.

The role of behavioral adjustment in placing middle school students at risk academically is examined using 23 middle school teachers' and 378 parents' ratings of 389 children (53 percent blacks and 47 percent whites) on Conner's Parent Rating Scale and Conner's Teacher Rating Scale. The average rating on the scales for both sets of ratings is…

Aggressive Marital Conflict, Maternal Harsh Punishment, and Child Aggressive-Disruptive Behavior: Evidence for Direct and Mediated Relations

PubMed Central

Erath, Stephen A.; Bierman, Karen L.

2009-01-01

Direct associations between aggressive marital conflict and child aggressive-disruptive behavior at home and school were explored in this cross-sectional study of 360 kindergarten children. In addition, mediated pathways linking aggressive marital conflict to maternal harsh punishment to child aggressive-disruptive behavior were examined. Moderation analyses explored how the overall frequency of marital disagreement might buffer or exacerbate the impact of aggressive marital conflict on maternal harsh punishment and child aggressive-disruptive behavior. Hierarchical regressions revealed direct pathways linking aggressive marital conflict to child aggressive-disruptive behavior at home and school and a partially mediated pathway linking aggressive marital conflict to child aggressive-disruptive behavior at home. Further analyses revealed that rates of marital disagreement moderated the association between aggressive marital conflict and child aggressive-disruptive behavior at home, with an attenuated association at high rates of marital disagreement as compared with low rates of marital disagreement. PMID:16756397

Test Review: Autism Spectrum Rating Scales

ERIC Educational Resources Information Center

Simek, Amber N.; Wahlberg, Andrea C.

2011-01-01

This article reviews Autism Spectrum Rating Scales (ASRS) which are designed to measure behaviors in children between the ages of 2 and 18 that are associated with disorders on the autism spectrum as rated by parents/caregivers and/or teachers. The rating scales include items related to behaviors associated with Autism, Asperger's Disorder, and…

The Dynamic Flow and Failure Behavior of Magnesium and Magnesium Alloys

NASA Astrophysics Data System (ADS)

Eswar Prasad, K.; Li, B.; Dixit, N.; Shaffer, M.; Mathaudhu, S. N.; Ramesh, K. T.

2014-01-01

We review the dynamic behavior of magnesium alloys through a survey of the literature and a comparison with our own high-strain-rate experiments. We describe high-strain-rate experiments (at typical strain rates of 103 s-1) on polycrystalline pure magnesium as well as two magnesium alloys, AZ31B and ZK60. Both deformation and failure are considered. The observed behaviors are discussed in terms of the fundamental deformation and failure mechanisms in magnesium, considering the effects of grain size, strain rate, and crystallographic texture. A comparison of current results with the literature studies on these and other Mg alloys reveals that the crystallographic texture, grain size, and alloying elements continue to have a profound influence on the high-strain-rate deformation behavior. The available data set suggests that those materials loaded so as to initiate extension twinning have relatively rate-insensitive strengths up to strain rates of several thousand per second. In contrast, some rate dependence of the flow stress is observed for loading orientations in which the plastic flow is dominated by dislocation mechanisms.

Effects of Motivation on Students' Ratings of Tutor Behavior.

ERIC Educational Resources Information Center

Gijselaers, Wim H.; Nuy, Herman

This study, which took place in Maastricht (Netherlands), examined whether motivation affects the reliability of students' ratings about tutor behavior and whether different types of students have different expectations about tutor behavior. Four types of motivation were measured: intrinsic, extrinsic, and achievement motivation, and fear of…

Behavioral Cues in the Judgment of Marital Satisfaction: A Linear Regression Analysis

ERIC Educational Resources Information Center

Royce, W. Stephen; Weiss, Robert L.

1975-01-01

Forty undergraduate judges watched videotaped interactions of couples and rated their marital satisfaction based on certain behavioral cues. Results indicate: untrained judges were able to discriminate marital satisfaction/distress with significant validity; judges' ratings were correlated with couples' aversive behavior; and the actuarial…

Behavioral training enhances cortical temporal processing in neonatally deafened juvenile cats

PubMed Central

Vollmer, Maike; Raggio, Marcia W.; Schreiner, Christoph E.

2011-01-01

Deaf humans implanted with a cochlear prosthesis depend largely on temporal cues for speech recognition because spectral information processing is severely impaired. Training with a cochlear prosthesis is typically required before speech perception shows improvement, suggesting that relevant experience modifies temporal processing in the central auditory system. We tested this hypothesis in neonatally deafened cats by comparing temporal processing in the primary auditory cortex (AI) of cats that received only chronic passive intracochlear electric stimulation (ICES) with cats that were also trained with ICES to detect temporally challenging trains of electric pulses. After months of chronic passive stimulation and several weeks of detection training in behaviorally trained cats, multineuronal AI responses evoked by temporally modulated ICES were recorded in anesthetized animals. The stimulus repetition rates that produced the maximum number of phase-locked spikes (best repetition rate) and 50% cutoff rate were significantly higher in behaviorally trained cats than the corresponding rates in cats that received only chronic passive ICES. Behavioral training restored neuronal temporal following ability to levels comparable with those recorded in naïve prior normal-hearing adult deafened animals. Importantly, best repetitition rates and cutoff rates were highest for neuronal clusters activated by the electrode configuration used in behavioral training. These results suggest that neuroplasticity in the AI is induced by behavioral training and perceptual learning in animals deprived of ordinary auditory experience during development and indicate that behavioral training can ameliorate or restore temporal processing in the AI of profoundly deaf animals. PMID:21543753

Definitions of homework, types of homework, and ratings of the importance of homework among psychologists with cognitive behavior therapy and psychoanalytic theoretical orientations.

PubMed

Kazantzis, Nikolaos; Dattilio, Frank M

2010-07-01

A random sample of 827 psychologists were surveyed to assess their definitions of homework, use of homework tasks, and perceived importance of homework. Theoretical orientation distinguished practitioners' responses. Cognitive-behavioral therapists defined homework as being closer to empirically supported therapy, whereas psychodynamic therapists rated homework as less characteristic of a process that embraces client responsibility and adaptive skills. Cognitive-behavior therapists did not limit their choices to activity-based tasks, and psychodynamic therapists reported using behavioral tasks "sometimes." Monitoring dreams and conscious thought were also used among the entire sample surveyed. Psychodynamic therapists rated homework as "somewhat" or "moderately" important, whereas cognitive-behavior therapists more often rated homework as "very important." Data suggest some homework may be common to different psychotherapeutic approaches. Findings are discussed in the context of recent theoretical work on homework in psychotherapy and recommendations for future research.

Identifying emotional and behavioral risk among gifted and nongifted children: A multi-gate, multi-informant approach.

PubMed

Eklund, Katie; Tanner, Nick; Stoll, Katie; Anway, Leslie

2015-06-01

The purpose of the current investigation was to compare 1,206 gifted and nongifted elementary students on the identification of emotional and behavioral risk (EBR) as rated by teachers and parents using a multigate, multi-informant approach to assessment. The Parent and Teacher Behavioral Assessment System for Children, Second Edition (BASC-2) and the Behavioral and Emotional Screening System were used to assess behavioral functioning as rated by teachers and parents. There were significant differences between the number of gifted and nongifted children demonstrating emotional and behavioral risk, with parents and teachers identifying a higher number of boys and nongifted children as at risk. Among children demonstrating EBR, gifted children demonstrated elevated internalizing behaviors as rated by parents. Gifted students demonstrated higher academic performance regardless of risk level, suggesting higher cognitive abilities may be one of several protective factors that serve to attenuate the development of other social, emotional, or behavioral concerns. Implications for practice and future research needs are discussed. (c) 2015 APA, all rights reserved).

Behavior Problems in Postinstitutionalized Romanian Adoptees: Explanatory Parameters in the Adoptive Home

ERIC Educational Resources Information Center

Le Mare, Lucy; Audet, Karyn

2014-01-01

We examined behavior problems in 80 adolescents (39 male; mean age = 15.74 years) adopted in early childhood by Canadians from globally depriving Romanian institutions. Overall, rates of clinically significant behavior problems were comparable to rates found in younger postinstitutionalized adopted children. The association between duration of…

Item-Based Psychometrics of the Preschool Behavioral and Emotional Rating Scale

ERIC Educational Resources Information Center

Cress, Cynthia J.; Lambert, Matthew C.; Epstein, Michael H.

2014-01-01

The Preschool Behavioral and Emotional Rating Scale (PreBERS) is an assessment of emotional and behavioral strengths in preschoolers with well-established reliability and validity for educational and clinical application in children with and without disabilities. The present study provides further evidence of psychometric rigor for items and…

Comparison of Teacher-Rated Achievement Levels of Behaviorally Disordered, Learning Disabled, and Nonhandicapped Adolescents.

ERIC Educational Resources Information Center

Luebke, Jerry; And Others

1989-01-01

Teacher ratings on reading recognition, reading comprehension, arithmetic, and written expression revealed that behaviorally disordered and learning-disabled adolescents (N=200) were seen as performing significantly below expected levels of achievement. Differences between behaviorally disordered and learning-disabled students appeared to depend…

Temporal Stability and Convergent Validity of the Behavior Assessment System for Children.

ERIC Educational Resources Information Center

Merydith, Scott P.

2001-01-01

Assesses the temporal stability and convergent validity of the Behavioral Assessment System for Children (BASC). Teachers and parents rated kindergarten and first-grade students using BASC. Teachers were more stable in rating children's externalizing behaviors and attention problems. Discusses results in terms of the accuracy of information…

Behavioral Treatments and Pharmacotherapy: Acceptability Ratings by Elderly Individuals in Residential Settings.

ERIC Educational Resources Information Center

Burgio, Louis D.; Sinnott, Jan

1990-01-01

Presented residents of life care community and nursing homes with scenarios of older woman. Client varied by cognitive capacity and behavior problem (aggression, verbal abuse, noncompliance). Participants rated three treatments: differential reinforcement of incompatible behavior (DRI), time-out, and haloperidol. All treatments were acceptable;…

Relations among Student Attention Behaviors, Teacher Practices, and Beginning Word Reading Skill

ERIC Educational Resources Information Center

Saez, Leilani; Folsom, Jessica Sidler; Al Otaiba, Stephanie; Schatschneider, Christopher

2012-01-01

The role of student attention for predicting kindergarten word reading was investigated among 432 students. Using "Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Rating Scale" behavior rating scores, the authors conducted an exploratory factor analysis, which yielded three distinct factors that reflected selective…

Nonsuicidal self-injury: relationship to behavioral and self-rating measures of impulsivity and self-aggression.

PubMed

McCloskey, Michael S; Look, Amy E; Chen, Eunice Y; Pajoumand, Golnaz; Berman, Mitchell E

2012-04-01

Previous research using self-report measures has shown an association between nonsuicidal self-injurious behavior (NSSI) and impulsive tendencies. However, self-injurers have not been shown to be different from comparison groups on laboratory tasks putatively assessing impulsive behavior. One explanation for these contradictory findings is that self-report and laboratory measures of impulsive behavior tap into distinct but related constructs. Moreover, performance on laboratory measures of impulsive behavior can be influenced by myriad contextual and affective factors not present during past self-reported NSSI events. Accordingly, a relationship between behavioral tasks of impulsivity and self-injurious behavior could emerge if both are assessed relatively close in time under controlled laboratory conditions. To test this possibility, both self-ratings and laboratory task measures of self-injurious and impulsive behavior were employed in the current study. This multi-modal assessment approach revealed that self-rated impulsivity was associated with both self-report and behavioral measures of self-injurious behavior. Moreover, behavioral measures of impulsivity were associated with self-injurious behavior, but not NSSI history. These results provide support for the notion that a multi-modal approach to assessing self-injurious behavior is important for better understanding the correlates of nonsuicidal self-injury. © 2012 The American Association of Suicidology.

Base Rates of Social Skills Acquisition/Performance Deficits, Strengths, and Problem Behaviors: An Analysis of the Social Skills Improvement System-Rating Scales

ERIC Educational Resources Information Center

Gresham, Frank M.; Elliott, Stephen N.; Kettler, Ryan J.

2010-01-01

Base rate information is important in clinical assessment because one cannot know how unusual or typical a phenomenon is without first knowing its base rate in the population. This study empirically determined the base rates of social skills acquisition and performance deficits, social skills strengths, and problem behaviors using a nationally…

Evaluation of the Problem Behavior Frequency Scale-Teacher Report Form for Assessing Behavior in a Sample of Urban Adolescents.

PubMed

Farrell, Albert D; Goncy, Elizabeth A; Sullivan, Terri N; Thompson, Erin L

2018-02-01

This study evaluated the structure and validity of the Problem Behavior Frequency Scale-Teacher Report Form (PBFS-TR) for assessing students' frequency of specific forms of aggression and victimization, and positive behavior. Analyses were conducted on two waves of data from 727 students from two urban middle schools (Sample 1) who were rated by their teachers on the PBFS-TR and the Social Skills Improvement System (SSIS), and on data collected from 1,740 students from three urban middle schools (Sample 2) for whom data on both the teacher and student report version of the PBFS were obtained. Confirmatory factor analyses supported first-order factors representing 3 forms of aggression (physical, verbal, and relational), 3 forms of victimization (physical, verbal and relational), and 2 forms of positive behavior (prosocial behavior and effective nonviolent behavior), and higher-order factors representing aggression, victimization, and positive behavior. Strong measurement invariance was established over gender, grade, intervention condition, and time. Support for convergent validity was found based on correlations between corresponding scales on the PBFS-TR and teacher ratings on the SSIS in Sample 1. Significant correlations were also found between teacher ratings on the PBFS-TR and student ratings of their behavior on the Problem Behavior Frequency Scale-Adolescent Report (PBFS-AR) and a measure of nonviolent behavioral intentions in Sample 2. Overall the findings provided support for the PBFS-TR and suggested that teachers can provide useful data on students' aggressive and prosocial behavior and victimization experiences within the school setting. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Human behavioral thermoregulation during exercise in the heat.

PubMed

Flouris, A D; Schlader, Z J

2015-06-01

The human capacity to perform prolonged exercise is impaired in hot environments. To address this issue, a number of studies have investigated behavioral aspects of thermoregulation that are recognized as important factors in determining performance. In this review, we evaluated and interpreted the available knowledge regarding the voluntary control of exercise work rate in hot environments. Our analysis indicated that: (a) Voluntary reductions in exercise work rate in uncompensable heat aid thermoregulation and are, therefore, thermoregulatory behaviors. (b) Unlike thermal behavior during rest, the role of thermal comfort as the ultimate mediator of thermal behavior during exercise in the heat remains uncertain. By contrast, the rating of perceived exertion appears to be the key perceptual controller under such conditions, with thermal perception playing a more modulatory role. (c) Prior to increases in core temperature (when only skin temperature is elevated), reductions in self-selected exercise work rate in the heat are likely mediated by thermal perception (thermal comfort and sensation) and its influence on the rating of perceived exertion. (d) However, when both core and skin temperatures are elevated, factors associated with cardiovascular strain likely dictate the rate of perceived exertion response, thereby mediating such voluntary reductions in exercise work rate. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Child and Informant Influences on Behavioral Ratings of Preschool Children

PubMed Central

Phillips, Beth M.; Lonigan, Christopher J.

2015-01-01

This study investigated relations among teacher, parent, and observer behavioral ratings of 3- and 4-year-old children using intraclass correlations and ANOVA. Comparisons within and across children from middle- (N =166; Mean age 54.25 months, SD = 8.74) and low-income (N =199; Mean age 51.21 months, SD = 7.22) backgrounds revealed significant agreement between the raters but also considerable differences in both ranking and absolute scores between raters. Teachers and parents consistently rated children from low-income classrooms as having more behavioral problems and fewer prosocial behaviors. Results are conceptualized with respect to how differential expectations, comparison groups, and types of interaction with children can affect the evaluation of child behavior. Results point to the need for multiple sources of evaluation when assessing a child for behavioral difficulties, particularly in children from lower income backgrounds. PMID:25663717

Cerebral correlates of depressed behavior in rats, visualized using /sup 14/C-2-deoxyglucose autoradiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldecott-Hazard, S.; Mazziotta, J.; Phelps, M.

1988-06-01

/sup 14/C-2-Deoxyglucose (2DG) was used to investigate changes in the rate of cerebral metabolism in 3 rat models of depressed behavior. The models had already been established in the literature and were induced by injections of alpha-methyl-para-tyrosine, withdrawal from chronic amphetamine, or stress. We verified that exploratory behaviors were depressed in each model and that an antidepressant drug, tranylcypromine, prevented the depressed behavior in each model. 2DG studies revealed that the rate of regional glucose metabolism was elevated bilaterally in the lateral habenula of each of the 3 models. Regional metabolic rates were reduced in each model in the dorsalmore » medial prefrontal cortex, anterior ventral nucleus of the thalamus, and inferior colliculus. Forebrain global metabolic rates were also reduced in each of the models. Tranylcypromine prevented the elevated rate of lateral habenula metabolism seen in each of the models alone but did not significantly affect the rates of global metabolism. Our findings of identical metabolic changes in each of the models indicate that these changes are not idiosyncratic to a particular model; rather, they correlate with a generalizable state of depressed exploratory behavior in rats.« less

The Utility of Thin Slice Ratings for Predicting Language Growth in Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Walton, Katherine M.; Ingersoll, Brooke R.

2016-01-01

Literature on "Thin Slice" ratings indicates that a number of personality characteristics and behaviors can be accurately predicted by ratings of very short segments (<5?min) of behavior. This study examined the utility of Thin Slice ratings of young children with autism spectrum disorder for predicting developmental skills and…

M-Rated Video Games and Aggressive or Problem Behavior among Young Adolescents

ERIC Educational Resources Information Center

Olson, Cheryl K.; Kutner, Lawrence A.; Baer, Lee; Beresin, Eugene V.; Warner, Dorothy E.; Nicholi, Armand M., II

2009-01-01

This research examined the potential relationship between adolescent problem behaviors and amount of time spent with violent electronic games. Survey data were collected from 1,254 7th and 8th grade students in two states. A "dose" of exposure to Mature-rated games was calculated using Entertainment Software Rating Board ratings of…

The mediational role of parenting on the longitudinal relation between child personality and externalizing behavior.

PubMed

Prinzie, Peter; van der Sluis, Cathy M; de Haan, Amaranta D; Deković, Maja

2010-08-01

Building on prior cross-sectional work, this longitudinal study evaluated the proposition that maternal and paternal overreactive and authoritative parenting mediates the effect of child personality characteristics on externalizing behavior. Data from the Flemish Study on Parenting, Personality, and Problem Behavior were used in a moderated mediation analysis (N=434). Teachers rated children's Big Five characteristics, fathers and mothers rated their parenting, and 3 years later, children rated their externalizing behavior. Mediational analysis revealed both direct and indirect effects. Higher levels of Extraversion and lower levels of Benevolence were related directly to higher levels of child externalizing behavior. Higher levels of paternal authoritative parenting and lower levels of maternal overreactivity were related to lower scores on externalizing behavior. In addition, the relation between Benevolence, Emotional Stability, and externalizing behavior was partially mediated by parental overreactivity. Conscientiousness had an indirect effect on externalizing behavior through paternal authoritative parenting. Relations were not moderated by child gender. This study is of theoretical interest because the results demonstrate that parenting is a mediating mechanism that accounts for associations between personality and externalizing behavior.

Student, teacher, and classroom predictors of between-teacher variance of students' teacher-rated behavior.

PubMed

Splett, Joni W; Smith-Millman, Marissa; Raborn, Anthony; Brann, Kristy L; Flaspohler, Paul D; Maras, Melissa A

2018-03-08

The current study examined between-teacher variance in teacher ratings of student behavioral and emotional risk to identify student, teacher and classroom characteristics that predict such differences and can be considered in future research and practice. Data were taken from seven elementary schools in one school district implementing universal screening, including 1,241 students rated by 68 teachers. Students were mostly African America (68.5%) with equal gender (female 50.1%) and grade-level distributions. Teachers, mostly White (76.5%) and female (89.7%), completed both a background survey regarding their professional experiences and demographic characteristics and the Behavior Assessment System for Children (Second Edition) Behavioral and Emotional Screening System-Teacher Form for all students in their class, rating an average of 17.69 students each. Extant student data were provided by the district. Analyses followed multilevel linear model stepwise model-building procedures. We detected a significant amount of variance in teachers' ratings of students' behavioral and emotional risk at both student and teacher/classroom levels with student predictors explaining about 39% of student-level variance and teacher/classroom predictors explaining about 20% of between-teacher differences. The final model fit the data (Akaike information criterion = 8,687.709; pseudo-R2 = 0.544) significantly better than the null model (Akaike information criterion = 9,457.160). Significant predictors included student gender, race ethnicity, academic performance and disciplinary incidents, teacher gender, student-teacher gender interaction, teacher professional development in behavior screening, and classroom academic performance. Future research and practice should interpret teacher-rated universal screening of students' behavioral and emotional risk with consideration of the between-teacher variance unrelated to student behavior detected. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

First-grade classroom behavior: its short- and long-term consequences for school performance.

PubMed

Alexander, K L; Entwisle, D R; Dauber, S L

1993-06-01

Effects of children's classroom behavior on school performance over a 4-year period are examined for a large, representative panel of beginning first graders. Scales developed from homeroom teachers' ratings of children in the spring of their first, second, and fourth years of school are used to predict spring marks in reading and math and spring scores on verbal and quantitative subtests from the CAT battery. The teachers' ratings cluster in three domains: Interest-Participation (I-P), Cooperation-Compliance (C-C), and Attention Span-Restlessness (A-R). The I-P and A-R ratings, but not C-C ratings, affect test score gains in first grade and marks in all 3 years. Behavior ratings from Year 1 also affect Year 2 and Year 4 performance, with indications that effects are understated over single-year periods. The importance of assessing classroom behavior in a longitudinal framework that allows for lagged and cumulative effects is discussed.

The High Strain Rate Deformation Behavior of High Purity Magnesium and AZ31B Magnesium Alloy

NASA Astrophysics Data System (ADS)

Livescu, Veronica; Cady, Carl M.; Cerreta, Ellen K.; Henrie, Benjamin L.; Gray, George T.

The deformation in compression of pure magnesium and AZ31B magnesium alloy, both with a strong basal pole texture, has been investigated as a function of temperature, strain rate, and specimen orientation. The mechanical response of both metals is highly dependent upon the orientation of loading direction with respect to the basal pole. Specimens compressed along the basal pole direction have a high sensitivity to strain rate and temperature and display a concave down work hardening behavior. Specimens loaded perpendicularly to the basal pole have a yield stress that is relatively insensitive to strain rate and temperature and a work hardening behavior that is parabolic and then linearly upwards. Both specimen orientations display a mechanical response that is sensitive to temperature and strain rate. Post mortem characterization of the pure magnesium was conducted on a subset of specimens to determine the microstructural and textural evolution during deformation and these results are correlated with the observed work hardening behavior and strain rate sensitivities were calculated.

Establishment of joint attention in dyads involving hearing mothers of deaf and hearing children, and its relation to adaptive social behavior.

PubMed

Nowakowski, Matilda E; Tasker, Susan L; Schmidt, Louis A

2009-01-01

Mounting evidence points to joint attention as a mediating variable in children's adaptive behavior development. Joint attention in interactions between hearing mothers and congenitally deaf (n = 27) and hearing (n = 29) children, ages 18-36 months, was examined. All deaf children had severe to profound hearing loss. Mother-child interactions were coded for maternally initiated and child-initiated success rates in establishing joint attention; mothers completed ratings of their children's adaptive behavior. Hearing mother-deaf child dyads had significantly lower maternally initiated success rates. No significant between-group differences on child-initiated success rates were shown. Maternal ratings of adaptive behavior were significantly lower for deaf children, and related positively and significantly to both child-initiated and maternally initiated success rates. The findings suggest that mother-child interactions that are low in successful establishment of joint attention might mediate the development of socioemotional problems evident in deaf children with hearing families.

Prevalence of multiple health-related behaviors in adolescents with cancer.

PubMed

Carpentier, Melissa Y; Mullins, Larry L; Elkin, T David; Wolfe-Christensen, Cortney

2008-12-01

This preliminary study investigated prevalence rates of multiple health-related behaviors (ie, tobacco, alcohol, and other drug use; sexual risk-taking; nutrition/physical activity; overweight and dietary behaviors; sun safety) among 42 adolescents on active treatment for cancer, as compared with healthy adolescent norms. Health-related behaviors were assessed using the 2005 National Youth Risk Behavior Survey, for which healthy adolescent norms were publicly available. Adolescents with cancer reported significantly lower current and lifetime rates of tobacco, alcohol, and other drug use; fruit/vegetable consumption; physical activity; and dietary behavior, in addition to lower rates of lifetime sexual intercourse, early-onset sexual intercourse, and alcohol/drug use before last sexual intercourse, compared with healthy peers. Among those who have previously engaged in sexual intercourse, there appeared to be a trend toward increased partners, current sexual activity, and lack of protection at last episode of sexual intercourse. Adolescents with cancer also reported significantly higher rates of television watching compared with healthy peers. Adolescents on active treatment for cancer are engaging in multiple health-risk behaviors, including sedentary behavior, poor nutrition, lack of sun safety, and sexual risk-taking (eg, multiple partners, lack of protection at last sexual intercourse). Health promotion interventions are needed during active treatment to facilitate the acquisition of good health practices as adolescents transition into survivorship.

Behavioral economics

PubMed Central

Hursh, Steven R.

1984-01-01

Economics, like behavioral psychology, is a science of behavior, albeit highly organized human behavior. The value of economic concepts for behavioral psychology rests on (1) their empirical validity when tested in the laboratory with individual subjects and (2) their uniqueness when compared to established behavioral concepts. Several fundamental concepts are introduced and illustrated by reference to experimental data: open and closed economies, elastic and inelastic demand, and substitution versus complementarity. Changes in absolute response rate are analyzed in relation to elasticity and intensity of demand. The economic concepts of substitution and complementarity are related to traditional behavioral studies of choice and to the matching relation. The economic approach has many implications for the future of behavioral research and theory. In general, economic concepts are grounded on a dynamic view of reinforcement. The closed-economy methodology extends the generality of behavioral principles to situations in which response rate and obtained rate of reinforcement are interdependent. Analysis of results in terms of elasticity and intensity of demand promises to provide a more direct method for characterizing the effects of “motivational” variables. Future studies of choice should arrange heterogeneous reinforcers with varying elasticities, use closed economies, and modulate scarcity or income. The economic analysis can be extended to the study of performances that involve subtle discriminations or skilled movements that vary in accuracy or quality as opposed to rate or quantity, and thus permit examination of time/accuracy trade-offs. PMID:16812401

A structured observation of behavioral self-regulation and its contribution to kindergarten outcomes.

PubMed

Ponitz, Claire Cameron; McClelland, Megan M; Matthews, J S; Morrison, Frederick J

2009-05-01

The authors examined a new assessment of behavioral regulation and contributions to achievement and teacher-rated classroom functioning in a sample (N = 343) of kindergarteners from 2 geographical sites in the United States. Behavioral regulation was measured with the Head-Toes-Knees-Shoulders (HTKS) task, a structured observation requiring children to perform the opposite of a dominant response to 4 different oral commands. Results revealed considerable variability in HTKS scores. Evidence for construct validity was found in positive correlations with parent ratings of attentional focusing and inhibitory control and teacher ratings of classroom behavioral regulation. Hierarchical linear modeling indicated that higher levels of behavioral regulation in the fall predicted stronger levels of achievement in the spring and better teacher-rated classroom self-regulation (all ps < .01) but not interpersonal skills. Evidence for domain specificity emerged, in which gains in behavioral regulation predicted gains in mathematics but not in language and literacy over the kindergarten year (p < .01) after site, child gender, and other background variables were controlled. Discussion focuses on the importance of behavioral regulation for successful adjustment to the demands of kindergarten. Copyright 2009 APA, all rights reserved

Symptoms of Persistent Behavior Problems in Children with Mild Traumatic Brain Injury

PubMed Central

Taylor, H. Gerry; Orchinik, Leah J.; Minich, Nori; Dietrich, Ann; Nuss, Kathryn; Wright, Martha; Bangert, Barbara; Rusin, Jerome; Yeates, Keith Owen

2014-01-01

Objective To investigate the effects of mild traumatic brain injury (mTBI) in children on symptom ratings of behavior problems across the first year post injury. Setting Emergency departments of two regional children’s hospitals. Participants Parents of 176 children with mTBI and 90 with orthopedic injury (OI) ages 8–15 years. Design Group comparisons of post-injury parent and teacher ratings of child behavior problems controlling for background factors. Main Measures Child Behavior Checklist (CBCL) and Teacher’s Report Form (TRF). Results For younger but not older children in the sample, children with mTBI compared to those with OI had higher post-injury ratings on the CBCL Total Behavior Problem scale, t (264) = 3.34, p<.001, and higher rates of T-scores ≥ 60 on this scale, OR (CI) = 3.00 (1.33, 6.77), p=.008. For children with mTBI, hospitalization, motor vehicle accidents, loss of consciousness, and MRI abnormality were associated with higher parent or teacher ratings. Conclusions School-age children with mTBI are at risk for persistent symptoms of behavior problems, especially if mTBI is more severe or occurs at a younger age. The findings justify monitoring of behavior long after injury and further research to identify risk factors for these symptoms and their association with clinical disorders. PMID:25629259

Resting heart rate and the development of antisocial behavior from age 9 to 14: genetic and environmental influences.

PubMed

Baker, Laura A; Tuvblad, Catherine; Reynolds, Chandra; Zheng, Mo; Lozano, Dora Isabel; Raine, Adrian

2009-01-01

The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old.

A Comparison of Geodetic and Geologic Rates Prior to Large Strike-Slip Earthquakes: A Diversity of Earthquake-Cycle Behaviors?

NASA Astrophysics Data System (ADS)

Dolan, James F.; Meade, Brendan J.

2017-12-01

Comparison of preevent geodetic and geologic rates in three large-magnitude (Mw = 7.6-7.9) strike-slip earthquakes reveals a wide range of behaviors. Specifically, geodetic rates of 26-28 mm/yr for the North Anatolian fault along the 1999 MW = 7.6 Izmit rupture are ˜40% faster than Holocene geologic rates. In contrast, geodetic rates of ˜6-8 mm/yr along the Denali fault prior to the 2002 MW = 7.9 Denali earthquake are only approximately half as fast as the latest Pleistocene-Holocene geologic rate of ˜12 mm/yr. In the third example where a sufficiently long pre-earthquake geodetic time series exists, the geodetic and geologic rates along the 2001 MW = 7.8 Kokoxili rupture on the Kunlun fault are approximately equal at ˜11 mm/yr. These results are not readily explicable with extant earthquake-cycle modeling, suggesting that they may instead be due to some combination of regional kinematic fault interactions, temporal variations in the strength of lithospheric-scale shear zones, and/or variations in local relative plate motion rate. Whatever the exact causes of these variable behaviors, these observations indicate that either the ratio of geodetic to geologic rates before an earthquake may not be diagnostic of the time to the next earthquake, as predicted by many rheologically based geodynamic models of earthquake-cycle behavior, or different behaviors characterize different fault systems in a manner that is not yet understood or predictable.

Egg turning behavior and incubation temperature in Forster’s terns in relation to mercury contamination

USGS Publications Warehouse

Taylor, Gregory T.; Ackerman, Joshua T.; Shaffer, Scott A.

2018-01-01

Egg turning behavior is an important determinant of egg hatchability, but it remains relatively understudied. Here, we examined egg turning rates and egg temperatures in Forster’s terns (Sterna forsteri). We used artificial eggs containing a data logger with a 3-D accelerometer, a magnetometer, and a temperature thermistor to monitor parental incubation behavior of 131 tern nests. Overall, adults turned their eggs an average (±SD) of 3.8 ± 0.8 turns h-1, which is nearly two times higher than that of other seabirds. Egg turning rates increased with nest initiation date. We also examined egg turning rates and egg temperatures in relation to egg mercury contamination. Mercury contamination has been shown to be associated with reduced egg hatchability, and we hypothesized that mercury may decrease egg hatchability via altered egg turning behavior by parents. Despite the high variability in egg turning rates among individuals, the rate of egg turning was not related to mercury concentrations in sibling eggs. These findings highlight the need for further study concerning the potential determinants of egg turning behavior.

Egg turning behavior and incubation temperature in Forster's terns in relation to mercury contamination.

PubMed

Taylor, Gregory T; Ackerman, Joshua T; Shaffer, Scott A

2018-01-01

Egg turning behavior is an important determinant of egg hatchability, but it remains relatively understudied. Here, we examined egg turning rates and egg temperatures in Forster's terns (Sterna forsteri). We used artificial eggs containing a data logger with a 3-D accelerometer, a magnetometer, and a temperature thermistor to monitor parental incubation behavior of 131 tern nests. Overall, adults turned their eggs an average (±SD) of 3.8 ± 0.8 turns h-1, which is nearly two times higher than that of other seabirds. Egg turning rates increased with nest initiation date. We also examined egg turning rates and egg temperatures in relation to egg mercury contamination. Mercury contamination has been shown to be associated with reduced egg hatchability, and we hypothesized that mercury may decrease egg hatchability via altered egg turning behavior by parents. Despite the high variability in egg turning rates among individuals, the rate of egg turning was not related to mercury concentrations in sibling eggs. These findings highlight the need for further study concerning the potential determinants of egg turning behavior.

Egg turning behavior and incubation temperature in Forster’s terns in relation to mercury contamination

PubMed Central

Ackerman, Joshua T.; Shaffer, Scott A.

2018-01-01

Egg turning behavior is an important determinant of egg hatchability, but it remains relatively understudied. Here, we examined egg turning rates and egg temperatures in Forster’s terns (Sterna forsteri). We used artificial eggs containing a data logger with a 3-D accelerometer, a magnetometer, and a temperature thermistor to monitor parental incubation behavior of 131 tern nests. Overall, adults turned their eggs an average (±SD) of 3.8 ± 0.8 turns h-1, which is nearly two times higher than that of other seabirds. Egg turning rates increased with nest initiation date. We also examined egg turning rates and egg temperatures in relation to egg mercury contamination. Mercury contamination has been shown to be associated with reduced egg hatchability, and we hypothesized that mercury may decrease egg hatchability via altered egg turning behavior by parents. Despite the high variability in egg turning rates among individuals, the rate of egg turning was not related to mercury concentrations in sibling eggs. These findings highlight the need for further study concerning the potential determinants of egg turning behavior. PMID:29447185

The Relationship of Parental Warm Responsiveness and Negativity to Emerging Behavior Problems Following Traumatic Brain Injury in Young Children

PubMed Central

Wade, Shari L.; Cassedy, Amy; Walz, Nicolay C.; Taylor, H. Gerry; Stancin, Terry; Yeates, Keith Owen

2013-01-01

Parenting behaviors play a critical role in the child's behavioral development, particularly for children with neurological deficits. This study examined the relationship of parental warm responsiveness and negativity to changes in behavior following traumatic brain injury (TBI) in young children relative to an age-matched cohort of children with orthopedic injuries (OI). It was hypothesized that responsive parenting would buffer the adverse effects of TBI on child behavior, whereas parental negativity would exacerbate these effects. Children, ages 3–7 years, hospitalized for TBI (n = 80) or OI (n = 113), were seen acutely and again 6 months later. Parent–child dyads were videotaped during free play. Parents completed behavior ratings (Child Behavior Checklist; T. M. Achenbach & L. A. Rescorla, 2001) at both visits, with baseline ratings reflecting preinjury behavior. Hypotheses were tested using multiple regression, with preinjury behavior ratings, race, income, child IQ, family functioning, and acute parental distress serving as covariates. Parental responsiveness and negativity had stronger associations with emerging externalizing behaviors and attention-deficit/hyperactivity disorder symptoms among children with severe TBI. Findings suggest that parenting quality may facilitate or impede behavioral recovery following early TBI. Interventions that increase positive parenting may partially ameliorate emerging behavior problems. PMID:21244154

Audiovisual video eyeglass distraction during dental treatment in children.

PubMed

Ram, Diana; Shapira, Joseph; Holan, Gideon; Magora, Florella; Cohen, Sarale; Davidovich, Esti

2010-09-01

To investigate the effect of audiovisual distraction (AVD) with video eyeglasses on the behavior of children undergoing dental restorative treatment and the satisfaction with this treatment as reported by children, parents, dental students, and experienced pediatric dentists. During restorative dental treatment, 61 children wore wireless audiovisual eyeglasses with earphones, and 59 received dental treatment under nitrous oxide sedation. A Frankl behavior rating score was assigned to each child. After each treatment, a Houpt behavior rating score was recorded by an independent observer. A visual analogue scale (VAS) score was obtained from children who wore AVD eyeglasses, their parents, and the clinician. General behavior during the AVD sessions, as rated by the Houpt scales, was excellent (rating 6) for 70% of the children, very good (rating 5) for 19%, good (rating 4) for 6%, and fair, poor, or aborted for only 5%. VAS scores showed 85% of the children, including those with poor Frankl ratings, to be satisfied with the AVD eyeglasses. Satisfaction of parents and clinicians was also high. Audiovisual eyeglasses offer an effective distraction tool for the alleviation of the unpleasantness and distress that arises during dental restorative procedures.

Neural correlates of behavioral amplitude modulation sensitivity in the budgerigar midbrain

PubMed Central

Neilans, Erikson G.; Abrams, Kristina S.; Idrobo, Fabio; Carney, Laurel H.

2016-01-01

Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. Whereas average discharge rates in the auditory midbrain correlate with behavioral AM sensitivity in rabbits, the neural bases of AM sensitivity in species with human-like behavioral acuity are unexplored. Here, we used parallel behavioral and neurophysiological experiments to explore the neural (midbrain) bases of AM perception in an avian speech mimic, the budgerigar (Melopsittacus undulatus). Behavioral AM sensitivity was quantified using operant conditioning procedures. Neural AM sensitivity was studied using chronically implanted microelectrodes in awake, unrestrained birds. Average discharge rates of multiunit recording sites in the budgerigar midbrain were insufficient to explain behavioral sensitivity to modulation frequencies <100 Hz for both tone- and noise-carrier stimuli, even with optimal pooling of information across recording sites. Neural envelope synchrony, in contrast, could explain behavioral performance for both carrier types across the full range of modulation frequencies studied (16–512 Hz). The results suggest that envelope synchrony in the budgerigar midbrain may underlie behavioral sensitivity to AM. Behavioral AM sensitivity based on synchrony in the budgerigar, which contrasts with rate-correlated behavioral performance in rabbits, raises the possibility that envelope synchrony, rather than average discharge rate, might also underlie AM perception in other species with sensitive AM detection abilities, including humans. These results highlight the importance of synchrony coding of envelope structure in the inferior colliculus. Furthermore, they underscore potential benefits of devices (e.g., midbrain implants) that evoke robust neural synchrony. PMID:26843608

[Prevalence of deliberate self-harm and its relation with suicidal behaviors among students in middle schools in Beijing].

PubMed

Xing, Yi; Qiao, Yijuan; Duan, Jiali; Bai, Chengxu

2015-09-01

To understand the prevalence of deliberate self-harm in middle school students in Beijing, and explore the relationship between self-harm and suicidal behaviors. An anonymous self-administered questionnaire survey was conducted among 5 807 students selected through cluster random sampling from grade 9 to grade 12 in 16 middle schools in Beijing. Among the surveyed middle school students, 35.6% reported that they once had self-harm behaviors, 7.0% reported often had self-harm behaviors in the past 30 days before the survey. More girls reported self-harm behaviors than boys did. And the prevalence of self-harm behaviors was highest in girls in grade 8 and in boys in grade 9. The students in key senior high schools, or living with single or remarried parents were the risk population to have self-harm behaviors. Higher suicide behavior reporting rate was correlated with higher self-harm behavior reporting rate. Compared with students who reported no self-harm behaviors during the past month, the suicide behavior reporting rate in students reporting self-harm behaviors increased by 5.7-12.3 times. Deliberate self-harm behaviors were associated with suicide behaviors among middle school students in Beijing. Early psychological intervention and life education should be carried out among middle school students in order to find risk population and save their life.

Maternal ADHD: Parent-Child Interactions and Relations with Child Disruptive Behavior

ERIC Educational Resources Information Center

Zisser, Alison R.; Eyberg, Sheila M.

2012-01-01

This study examined how ADHD symptoms in mothers of children with ADHD relate to their behavior during parent-child interactions and to their children's disruptive behavior. Findings indicated that mothers' retrospective self-ratings of ADHD symptoms were related to their present negativity during parent-led play. Mothers' self-ratings of current…

Technical Adequacy of the Disruptive Behavior Rating Scale-2nd Edition--Self-Report

ERIC Educational Resources Information Center

Erford, Bradley T.; Miller, Emily M.; Isbister, Katherine

2015-01-01

This study provides preliminary analysis of the Disruptive Behavior Rating Scale-2nd Edition--Self-Report, which was designed to screen individuals aged 10 years and older for anxiety and behavior symptoms. Score reliability and internal and external facets of validity were good for a screening-level test.

An Evaluation of the Predictive Validity of Confidence Ratings in Identifying Functional Behavioral Assessment Hypothesis Statements

ERIC Educational Resources Information Center

Borgmeier, Chris; Horner, Robert H.

2006-01-01

Faced with limited resources, schools require tools that increase the accuracy and efficiency of functional behavioral assessment. Yarbrough and Carr (2000) provided evidence that informant confidence ratings of the likelihood of problem behavior in specific situations offered a promising tool for predicting the accuracy of function-based…

The Genetic Etiology of Inhibitory Control and Behavior Problems at 24 Months of Age

ERIC Educational Resources Information Center

Gagne, Jeffrey R.; Saudino, Kimberly J.; Asherson, Philip

2011-01-01

Background: To investigate links between inhibitory control (IC) and behavior problems in early childhood, as well as genetic and environmental covariances between these two constructs. Methods: Parent and laboratory ratings of IC and parent ratings of externalizing and attention deficit hyperactivity disorder behaviors were administered at 24…

The Application of Structural Equation Modeling to Maternal Ratings of Twins' Behavior and Emotional Problems.

ERIC Educational Resources Information Center

Silberg, Judy L.; And Others

1994-01-01

Applied structural equation modeling to twin data to assess impact of genetic and environmental factors on children's behavioral and emotional functioning. Applied models to maternal ratings of behavior of 515 monozygotic and 749 dizygotic twin pairs. Importance of genetic, shared, and specific environmental factors for explaining variation was…

Factor Structure of the Behavior Flexibility Rating Scale (BFRS)

ERIC Educational Resources Information Center

Pituch, Keenan A.; Green, Vanessa A.; Sigafoos, Jeff; Itchon, Jonathan; O'Reilly, Mark; Lancioni, Giulio E.; Didden, Robert

2007-01-01

The Behavior Flexibility Rating Scale (BFRS) is designed to assess insistence on sameness or lack of behavioral flexibility, which is often associated with autism and other developmental disabilities. This study was designed to assess the factor structure of this scale for a sample of 968 individuals with autism, Asperger's syndrome, and Down…

Examining the Validity of Behavioral Self-Regulation Tools in Predicting Preschoolers' Academic Achievement

ERIC Educational Resources Information Center

Schmitt, Sara A.; Pratt, Megan E.; McClelland, Megan M.

2014-01-01

The current study investigated the predictive utility among teacher-rated, observed, and directly assessed behavioral self-regulation skills to academic achievement in preschoolers. Specifically, this study compared how a teacher report, the Child Behavior Rating Scale, an observer report, the Observed Child Engagement Scale, and a direct…

Examining the Validity of Behavioral Self-Regulation Tools in Predicting Preschoolers' Academic Achievement

ERIC Educational Resources Information Center

Schmitt, Sara A.; Pratt, Megan E.; McClelland, Megan M.

2014-01-01

Research Findings: The current study investigated the predictive utility of teacher-rated, observed, and directly assessed behavioral self-regulation skills to academic achievement in preschoolers. Specifically, this study compared how a teacher report (the Child Behavior Rating Scale), an observer report (the Observed Child Engagement Scale), and…

School Behavior and Attendance during the First Year of Treatment for Childhood Cancer.

ERIC Educational Resources Information Center

Stehbens, James A.; And Others

1983-01-01

Investigated school behavior and attendance of children with cancer (N=36) and hemophilia (N=26). Teacher ratings of students' behavior showed no differences before and after treatment. Children with cancer were absent four times more than healthy children; absenteeism of hemophiliacs was twice the normal rate. Academic performance was negatively…

Volunteers as Teachers of Child Management to Parents of Behaviour-Disordered Preschoolers.

ERIC Educational Resources Information Center

Seymour, Frederick W.; France, Karyn G.

1984-01-01

Ten women volunteers were trained as teachers of child management skills to parents of behavior-disordered preschoolers. Evaluation of the project's outcomes using a consumer satisfaction survey, parent ratings on a problem behavior checklist, and staff ratings of goal attainment, showed major changes in child behavior maintained at three-month…

Social Engagement with Peers and Stereotypic Behavior of Children with Autism

ERIC Educational Resources Information Center

Lee, SoHyun; Odom, Samuel L.; Loftin, Rachel

2007-01-01

In this study, the authors examined the relationship between engagement in social interaction with peers and stereotypic behavior. Three children with autism with relatively high rates of stereotypic behavior and low rates of social engagement with peers participated in the study. Two typically developing peers learned to direct social initiations…

Experimental Study and Modelling of Poly (Methyl Methacrylate) and Polycarbonate Compressive Behavior from Low to High Strain Rates

NASA Astrophysics Data System (ADS)

El-Qoubaa, Z.; Colard, L.; Matadi Boumbimba, R.; Rusinek, A.

2018-06-01

This paper concerns an experimental investigation of Polycarbonate and Poly (methyl methacrylate) compressive behavior from low to high strain rates. Experiments were conducted from 0.001/s to ≈ 5000/s for PC and from 0.001/s to ≈ 2000/s for PMMA. The true strain-stress behavior is established and analyzed at various stain rates. Both PC and PMMA mechanical behavior appears as known, to be strain rate and temperature dependent. The DSGZ model is selected for modelling the strain-stress curves while the yield stress is reproduced using the cooperative model and a modified Eyring equation based on Eyring first process theory. All the three models predictions are in agreement with experiments performed on PC and PMMA.

Experimental Study and Modelling of Poly (Methyl Methacrylate) and Polycarbonate Compressive Behavior from Low to High Strain Rates

NASA Astrophysics Data System (ADS)

El-Qoubaa, Z.; Colard, L.; Matadi Boumbimba, R.; Rusinek, A.

2018-03-01

This paper concerns an experimental investigation of Polycarbonate and Poly (methyl methacrylate) compressive behavior from low to high strain rates. Experiments were conducted from 0.001/s to ≈ 5000/s for PC and from 0.001/s to ≈ 2000/s for PMMA. The true strain-stress behavior is established and analyzed at various stain rates. Both PC and PMMA mechanical behavior appears as known, to be strain rate and temperature dependent. The DSGZ model is selected for modelling the strain-stress curves while the yield stress is reproduced using the cooperative model and a modified Eyring equation based on Eyring first process theory. All the three models predictions are in agreement with experiments performed on PC and PMMA.

Social Adversity and Antisocial Behavior: Mediating Effects of Autonomic Nervous System Activity.

PubMed

Fagan, Shawn E; Zhang, Wei; Gao, Yu

2017-11-01

The display of antisocial behaviors in children and adolescents has been of interest to criminologists and developmental psychologists for years. Exposure to social adversity is a well-documented predictor of antisocial behavior. Additionally, measures of autonomic nervous system (ANS) activity, including heart rate variability (HRV), pre-ejection period (PEP), and heart rate, have been associated with antisocial behaviors including rule-breaking and aggression. Social neuroscience research has begun to investigate how neurobiological underpinnings affect the relationship between social adversity and antisocial/psychopathic behavior in children and adolescents. This study investigated the potential mediating effects of ANS activity on the relationship between social adversity and antisocial behavior in a group of 7- to 10-year-old children from the community (N = 339; 48.2% male). Moderated multiple mediation analyses revealed that low resting heart rate, but not PEP or HRV, mediated the relationship between social adversity and antisocial behavior in males only. Social adversity but not ANS measures were associated with antisocial behavior in females. Findings have implications for understanding the neural influences that underlie antisocial behavior, illustrate the importance of the social environment regarding the expression of these behaviors, and highlight essential gender differences.

Social Skills Intervention Planning for Preschoolers: Using the SSiS-Rating Scales to Identify Target Behaviors Valued by Parents and Teachers

ERIC Educational Resources Information Center

Frey, Jennifer R.; Elliott, Stephen N.; Kaiser, Ann P.

2014-01-01

Teachers' and parents' importance ratings of social behaviors for 95 preschoolers were examined using the "Social Skills Improvement System-Rating Scales" (Gresham & Elliott, 2008). Multivariate analyses were used to examine parents' and teachers' importance ratings at the item and subscale levels. Overall,…

The behavioral response of Lasioderma serricorne (Coleoptera: Anobiidae) to citronellal, citral, and rutin.

PubMed

Lü, Jianhua; Liu, Shuli

2016-01-01

The behavioral response of Lasioderma serricorne adults to citronellal, citral, and rutin was investigated by using the area preference method. The L. serricorne adults were exposed to citronellal, and citral at the rate of 1:10, 1:50, 1:100 and 1:1000 (citronellal: ethanol, v/v) for 1, 2, 12 and 24 h, to rutin at the rate of 10, 30 and 90 g/m(2) for 1, 2, 12 and 24 h, respectively. The citronellal and citral had attractive activity at the low rates and repellent potential at the high rates. The highest behavioral response values of L. serricorne adults to citronellal and citral were -88.89 % at the rate of 1:100 and 100.00 % at the rate of 1:50 respectively. Rutin had strong repellent effectiveness on L. serricorne adults, which significantly increased with increasing rates with the highest behavioral response values 100.00 % at the rate of 90 g/m(2) after 12 h exposure. These data suggest that the citronellal, citral, and rutin have great potential for preventing stored products from L. serricorne infestation.

Dimensions of postconcussive symptoms in children with mild traumatic brain injuries.

PubMed

Ayr, Lauren K; Yeates, Keith Owen; Taylor, H Gerry; Browne, Michael

2009-01-01

The dimensions of postconcussive symptoms (PCS) were examined in a prospective, longitudinal study of 186 8 to 15 year old children with mild traumatic brain injuries (TBI). Parents and children completed a 50-item questionnaire within 2 weeks of injury and again at 3 months after injury, rating the frequency of PCS on a 4-point scale. Common factor analysis with target rotation was used to rotate the ratings to four hypothesized dimensions, representing cognitive, somatic, emotional, and behavioral symptoms. The rotated factor matrix for baseline parent ratings was consistent with the target matrix. The rotated matrix for baseline child ratings was consistent with the target matrix for cognitive and somatic symptoms but not for emotional and behavioral symptoms. The rotated matrices for ratings obtained 3 months after injury were largely consistent with the target matrix derived from analyses of baseline ratings, except that parent ratings of behavioral symptoms did not cluster as before. Parent and child ratings of PCS following mild TBI yield consistent factors reflecting cognitive and somatic symptom dimensions, but dimensions of emotional and behavioral symptoms are less robust across time and raters. (JINS, 2009, 15, 19-30.).

Dangerous student car drop-off behaviors and child pedestrian-motor vehicle collisions: An observational study.

PubMed

Rothman, Linda; Howard, Andrew; Buliung, Ron; Macarthur, Colin; Macpherson, Alison

2016-07-03

The objective of this study was to examine the association between dangerous student car drop-off behaviors and historical child pedestrian-motor vehicle collisions (PMVCs) near elementary schools in Toronto, Canada. Police-reported child PMVCs during school travel times from 2000 to 2011 were mapped within 200 m of 118 elementary schools. Observers measured dangerous student morning car drop-off behaviors and number of children walking to school during one day in 2011. A composite score of school social disadvantage was obtained from the Toronto District School Board. Built environment and traffic features were mapped and included as covariates. A multivariate Poisson regression was used to model the rates of PMVC/number of children walking and dangerous student car drop-off behaviors, adjusting for the built environment and social disadvantage. There were 45 child PMVCs, with 29 (64%) sustaining minor injuries resulting in emergency department visits. The mean collision rate was 2.9/10,000 children walking/year (SD = 6.7). Dangerous drop-off behaviors were observed in 104 schools (88%). In the multivariate analysis, each additional dangerous drop-off behavior was associated with a 45% increase in collision rates (incident rate ratio [IRR] = 1.45, 95% confidence interval [CI], 1.02, 2.07). Higher speed roads (IRR = 1.27, 95% CI, 1.13, 1.44) and social disadvantage (IRR = 2.99, 95% CI, 1.03, 8.68) were associated with higher collision rates. Dangerous student car drop-off behaviors were associated with historical nonfatal child PMVC rates during school travel times near schools. Some caution must be taken in interpreting these results due small number of events and limitations in the data collection, because collision data were collected historically over a 12-year period, whereas driving behavior was only observed on a single day in 2011. Targeted multifaceted intervention approaches related to the built environment, enforcement, and education could address dangerous drop-off behaviors near schools to reduce child PMVCs and promote safe walking to school.

Deficits in facial emotion recognition indicate behavioral changes and impaired self-awareness after moderate to severe traumatic brain injury.

PubMed

Spikman, Jacoba M; Milders, Maarten V; Visser-Keizer, Annemarie C; Westerhof-Evers, Herma J; Herben-Dekker, Meike; van der Naalt, Joukje

2013-01-01

Traumatic brain injury (TBI) is a leading cause of disability, specifically among younger adults. Behavioral changes are common after moderate to severe TBI and have adverse consequences for social and vocational functioning. It is hypothesized that deficits in social cognition, including facial affect recognition, might underlie these behavioral changes. Measurement of behavioral deficits is complicated, because the rating scales used rely on subjective judgement, often lack specificity and many patients provide unrealistically positive reports of their functioning due to impaired self-awareness. Accordingly, it is important to find performance based tests that allow objective and early identification of these problems. In the present study 51 moderate to severe TBI patients in the sub-acute and chronic stage were assessed with a test for emotion recognition (FEEST) and a questionnaire for behavioral problems (DEX) with a self and proxy rated version. Patients performed worse on the total score and on the negative emotion subscores of the FEEST than a matched group of 31 healthy controls. Patients also exhibited significantly more behavioral problems on both the DEX self and proxy rated version, but proxy ratings revealed more severe problems. No significant correlation was found between FEEST scores and DEX self ratings. However, impaired emotion recognition in the patients, and in particular of Sadness and Anger, was significantly correlated with behavioral problems as rated by proxies and with impaired self-awareness. This is the first study to find these associations, strengthening the proposed recognition of social signals as a condition for adequate social functioning. Hence, deficits in emotion recognition can be conceived as markers for behavioral problems and lack of insight in TBI patients. This finding is also of clinical importance since, unlike behavioral problems, emotion recognition can be objectively measured early after injury, allowing for early detection and treatment of these problems.

Adaptive self-regulation: meeting others' expectations of leadership and performance.

PubMed

Sosik, John J; Potosky, Denise; Jung, Dong I

2002-04-01

The authors used longitudinal multisource field data to examine core aspects of the adaptive self-regulation model (A. S. Tsui & S. J. Ashford, 1994) in terms of linkages between self-monitoring, discrepancy in manager match-to-position, 5 measures of leadership, and manager performance. At Time 1, 64 superiors of focal managers rated the managers' matches to their positions within the organization; at Time 3, they rated the managers' performance. At Time 2, the 64 focal managers completed a measure of self-monitoring, and 192 subordinates rated the focal managers' leadership behaviors. Results of partial least squares analysis revealed that discrepancy in manager match-to-position was associated with reductions in laissez faire and passive management-by-exception behaviors and increases in transformational leadership behavior. Self-monitoring was positively associated with all 5 leadership behaviors. Performance was related positively to transformational leadership behavior and negatively to passive management-by-exception and contingent-reward behaviors

Heart Rate Variability Responses of a Preterm Infant to Kangaroo Care

PubMed Central

McCain, Gail C.; Ludington-Hoe, Susan M.; Swinth, Joan Y.; Hadeed, Anthony J.

2006-01-01

A 35-week old preterm infant's behavior was fussy and restless in the open crib, but he calmed and fell asleep immediately on being placed skin-to-skin on his mother's chest. Heart rate variability (HRV), a noninvasive method to assess the autonomic nervous system's influence on heart rate, was increased with fussy behavior in the open crib and decreased with sleep during kangaroo care (KC). KC produced changes in behavior and HRV that are illustrative of decreasing stress. PMID:16282226

Song evolution, speciation, and vocal learning in passerine birds.

PubMed

Mason, Nicholas A; Burns, Kevin J; Tobias, Joseph A; Claramunt, Santiago; Seddon, Nathalie; Derryberry, Elizabeth P

2017-03-01

Phenotypic divergence can promote reproductive isolation and speciation, suggesting a possible link between rates of phenotypic evolution and the tempo of speciation at multiple evolutionary scales. To date, most macroevolutionary studies of diversification have focused on morphological traits, whereas behavioral traits─including vocal signals─are rarely considered. Thus, although behavioral traits often mediate mate choice and gene flow, we have a limited understanding of how behavioral evolution contributes to diversification. Furthermore, the developmental mode by which behavioral traits are acquired may affect rates of behavioral evolution, although this hypothesis is seldom tested in a phylogenetic framework. Here, we examine evidence for rate shifts in vocal evolution and speciation across two major radiations of codistributed passerines: one oscine clade with learned songs (Thraupidae) and one suboscine clade with innate songs (Furnariidae). We find that evolutionary bursts in rates of speciation and song evolution are coincident in both thraupids and furnariids. Further, overall rates of vocal evolution are higher among taxa with learned rather than innate songs. Taken together, these findings suggest an association between macroevolutionary bursts in speciation and vocal evolution, and that the tempo of behavioral evolution can be influenced by variation in developmental modes among lineages. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Agreement between parents and teachers on preschool children's behavior in a clinical sample with externalizing behavioral problems.

PubMed

Korsch, Franziska; Petermann, Franz

2014-10-01

An accurate interpretation of information obtained from multiple assessors is indispensible when complex diagnoses of behavioral problems in children need to be confirmed. The present study examined the similarity of parents and kindergarten teachers ratings on children's behavior in a sample of 160 preschool children (a clinical group including 80 children with externalizing behavioral problems and a matched control group including 80 children). Behavioral problems were assessed using the SDQ, and the DISYPS-II questionnaires for ADHD and conduct disorders. The results revealed low levels of parent-teacher agreement for their ratings on the children's behavior in both groups with the highest correlations in the non-clinical sample. Parent-teacher agreement did not differ significantly across the samples. Parent and teacher ratings correlated with the prevalence of externalizing disorders and were found to be almost independent of each other. The results highlight the importance of multiple informants and their independent influence within the diagnostic process.

Measuring behavioral regulation in four societies

PubMed Central

Wanless, Shannon B.; McClelland, Megan M.; Acock, Alan C.; Ponitz, Claire C.; Son, Seung-Hee; Lan, Xuezhao; Morrison, Frederick J.; Chen, Jo-Lin; Chen, Taiwan Fu-Mei; Lee, Taiwan Kangyi; Sung, Miyoung; Li, Su

2010-01-01

The present study examined the psychometric properties of scores from a direct measure of behavioral regulation, the Head-Toes-Knees-Shoulders task (HTKS) with 3- to 6-year-old children in the U.S., Taiwan, South Korea, and China. Specifically, we investigated (1) the nature and variability of HTKS scores including relations to teacher-rated classroom behavioral regulation, and (2) relations between the HTKS and early mathematics, vocabulary, and literacy skills. Higher HTKS scores were significantly related to higher teacher ratings of classroom behavioral regulation in the U.S. and South Korea but not in Taiwan and China. Also, higher HTKS scores were significantly related to higher early mathematics, vocabulary, and literacy skills beyond the influence of demographic variables and teacher-rated classroom behavioral regulation. These initial findings suggest that HTKS scores may be interpreted as reflecting early behavioral regulation in these four societies, and that behavioral regulation is important for early academic success in the U.S. and in Asian countries. PMID:21381840

Interplay between Hippocampal Sharp-Wave-Ripple Events and Vicarious Trial and Error Behaviors in Decision Making.

PubMed

Papale, Andrew E; Zielinski, Mark C; Frank, Loren M; Jadhav, Shantanu P; Redish, A David

2016-12-07

Current theories posit that memories encoded during experiences are subsequently consolidated into longer-term storage. Hippocampal sharp-wave-ripple (SWR) events have been linked to this consolidation process during sleep, but SWRs also occur during awake immobility, where their role remains unclear. We report that awake SWR rates at the reward site are inversely related to the prevalence of vicarious trial and error (VTE) behaviors, thought to be involved in deliberation processes. SWR rates were diminished immediately after VTE behaviors and an increase in the rate of SWR events at the reward site predicted a decrease in subsequent VTE behaviors at the choice point. Furthermore, SWR disruptions increased VTE behaviors. These results suggest an inverse relationship between SWRs and VTE behaviors and suggest that awake SWRs and associated planning and memory consolidation mechanisms are engaged specifically in the context of higher levels of behavioral certainty. Copyright © 2016 Elsevier Inc. All rights reserved.

Maternal Personal Resources and Children's Socioemotional and Behavioral Adjustment

ERIC Educational Resources Information Center

Al-Yagon, Michal

2008-01-01

The study examined the role of three maternal personal resources [sense of coherence (SOC), attachment style, and social/emotional feelings of loneliness] in explaining children's socioemotional adjustment (self-rated loneliness and SOC, and mother-rated child behavior) and children's (self-rated) secure attachment. The sample included 58…

Evaluation of the Bess TRS-CA Using the Rasch Rating Scale Model

ERIC Educational Resources Information Center

DiStefano, Christine; Morgan, Grant B.

2010-01-01

This study examined the Behavioral and Emotional Screening System Teacher Rating System for Children and Adolescents (BESS TRS-CA; Kamphaus & Reynolds, 2007) screener using Rasch Rating Scale model (RSM) methodology to provide additional information about psychometric properties of items. Data from the Behavioral Assessment System for Children…

Teacher Rated Empathic Behaviors and Children's TAT Stories.

ERIC Educational Resources Information Center

Locraft, Constance; Teglasi, Hedwig

1997-01-01

Focuses on the emotional/cognitive processes associated with teacher ratings of empathic and socially competent behaviors. Results indicate that children (N=120) with higher empathy ratings and at higher grade levels received higher scores on a storytelling measure--the Thematic Apperception Test. Clarifies the social information processing of…

Antisocial personality and bipolar disorder: interactions in impulsivity and course of illness

PubMed Central

Swann, Alan C

2011-01-01

SUMMARY Antisocial personality disorder (ASPD) and bipolar disorder are both characterized by impulsive behavior, increased incarceration or arrest, addictive disorders and suicidal behavior. These characteristics appear more severe in the combined disorders. Individuals with ASPD who also have bipolar disorder have higher rates of addictive disorders and suicidal behavior and are more impulsive, as measured by questionnaires or behavioral laboratory tests. Those with bipolar disorder who have ASPD have higher rates of addictive, criminal and suicidal behavior, earlier onset of bipolar disorder with a more recurrent and predominately manic course and increased laboratory-measured, but not questionnaire-rated, impulsivity. These characteristics may result in part from differential impulsivity mechanisms in the two disorders, with bipolar disorder driven more by excessive catecholamine sensitivity and ASPD by deficient serotonergic function. PMID:22235235

Consistency of Helping-Behavior Measures.

ERIC Educational Resources Information Center

Bar-Tal, Daniel; Raviv, Amiram

1979-01-01

Examines the consistency of various methods of measuring helping behavior. Questionnaires concerning helping behavior among 280 sixth graders and teachers' ratings were compared to measures of altruistic behavior and behavioral intention administered 2 years later. (CM)

Influence of dominance rank and affiliation relationships on self-directed behavior in female Tibetan macaques (Macaca thibetana).

PubMed

Zhang, Qi-Xin; Li, Jin-Hua; Xia, Dong-Po; Zhu, Yong; Wang, Xi; Zhang, Dao

2014-05-01

Self-directed behavior (SDB) is characterized as an indicator of anxiety, frustration and stress in nonhuman primates. In this study, we collected self-directed behavior data from one group of free-ranging Tibetan macaques (Macaca thibetana) at Mt. Huangshan, China (September 2012-May 2013) using a combination of behavioral sampling methods including focal animal sampling, behavioral sampling, continuous sampling and instantaneous sampling. Our results showed that females engaged in significantly higher rates of self-directed behavior when they were in proximity to dominant individuals compared to subordinate ones. Conflict losers significantly increased their SDB rates after agonistic episodes, indicating that SDB might also serve as an index of anxiety in M. thibetana. We further found that females significantly increased their SDB rates when focal individual was proximity to weakly affiliation relationship higher rank members than to strongly affiliation relationship higher rank members. If conflicts were not reconciled, the postconflict SDB rates of losers were higher when they stayed with strongly affiliation opponents; if conflicts were reconciled, victims of strongly affiliation relationships opponents engaged in more SDB rates before reconciliation than after reconciliation, while victims of moderately affiliation relationships opponents did not engaged in more SDB rates before reconciliation than after reconciliation. We conclude that both of dominance rank and affiliation relationships might both influence the SDB rates of female Tibetan macaques significantly, suggesting that SDB is not only an index of anxiety in Tibetan macaques, but also can provide a new insight into evaluation of social relationships between individuals.

Physiological state influences evaporative water loss and microclimate preference in the snake Vipera aspis.

PubMed

Dupoué, Andréaz; Stahlschmidt, Zachary R; Michaud, Bruno; Lourdais, Olivier

2015-05-15

Animals typically respond to environmental variation by adjusting their physiology, behavior, or both. Ectothermic animals are particularly sensitive to microclimatic conditions and behaviorally thermoregulate to optimize physiological performance. Yet, thermoregulation can be costly and may obligate a physiological tradeoff with water loss. Presumably, this tradeoff intensifies when animals undergo necessary life-history events (e.g., pregnancy or digestion) that impose significant behavioral and physiological changes, including shifts in behavioral thermoregulation and increased metabolic rate. Thus, behavioral responses, such as modified microclimatic preferences, may help mitigate the physiological tradeoff between thermoregulation and water loss. Herein, we examined the influence of major physiological states (specifically, pregnancy, ecdysis, and digestion) on evaporative water loss and on behavioral adjustments in a viviparous snake, Vipera aspis. First, we used open-flow respirometry to measure the effects of physiological states and microclimatic conditions (temperature and humidity) on the rate of total evaporative water loss (TEWL) and metabolic rate (rate of O2 consumption, V˙O2). Then, we experimentally tested the influence of physiological state on microclimate selection. We found that energy-demanding physiological states were associated with i) an increased rate of TEWL and V˙O2 compared to control states and ii) a slight preference (statistically marginal) for both warm and humid conditions compared to controls, suggesting a state-specificity in behavioral response. Overall our results underline the impact of physiological state on water loss and demonstrate the potential for behavior to mitigate the physiological tradeoff between thermoregulation and water balance. Copyright © 2015 Elsevier Inc. All rights reserved.

INDIVIDUAL DIFFERENCES IN IMPULSIVE CHOICE AND TIMING IN RATS

PubMed Central

Galtress, Tiffany; Garcia, Ana; Kirkpatrick, Kimberly

2012-01-01

Individual differences in impulsive choice behavior have been linked to a variety of behavioral problems including substance abuse, smoking, gambling, and poor financial decision-making. Given the potential importance of individual differences in impulsive choice as a predictor of behavioral problems, the present study sought to measure the extent of individual differences in a normal sample of hooded Lister rats. Three experiments utilized variations of a delay discounting task to measure the degree of variation in impulsive choice behavior across individual rats. The individual differences accounted for 22–55% of the variance in choice behavior across the three experiments. In Experiments 2 and 3, the individual differences were still apparent when behavior was measured across multiple choice points. Large individual differences in the rate of responding, and modest individual differences in timing of responding were also observed during occasional peak trials. The individual differences in timing and rate, however, did not correlate consistently with individual differences in choice behavior. This suggests that a variety of factors may affect choice behavior, response rate, and response timing. PMID:22851792

Portraying the Contribution of Individual Behaviors to Team Cohesion and Performance

NASA Technical Reports Server (NTRS)

Parke, Bonny; Orasanu, Judith

2012-01-01

Behaviors of individuals in teams both contribute to and are molded by team dynamics. How they do so has been the subject of much research. A method of portraying individuals' behaviors in teams, the Team Diagramming Method (TDM) is presented. Behaviors are rated by other team members on three important dimensions: positivity/negativity, dominant/submissive, and task-orientedness/expressiveness. A study of 5-person teams engaging in a 3-day moon simulation task demonstrated that measures of these perceived behaviors as well as the variances of these behaviors correlated with cohesion measures and performance. The method shows strengths and weaknesses of particular teams and, by comparison with high-performing teams, suggests interventions based on individual as well as team behaviors. The primary goal of this study was to determine the extent to which these team level variables, derived from all team members' rated behaviors, were associated with previous methods of measuring cohesion and with performance. A secondary goal was to determine the stability of TDM measures over time by comparing team level variables based on ratings early and later in the team s work together.

Examining parents' ratings of middle-school students' academic self-regulation using principal axis factoring analysis.

PubMed

Chen, Peggy P; Cleary, Timothy J; Lui, Angela M

2015-09-01

This study examined the reliability and validity of a parent rating scale, the Self-Regulation Strategy Inventory: Parent Rating Scale (SRSI-PRS), using a sample of 451 parents of sixth- and seventh-grade middle-school students. Principal axis factoring (PAF) analysis revealed a 3-factor structure for the 23-item SRSI-PRS: (a) Managing Behavior and Learning (α = .92), (b) Maladaptive Regulatory Behaviors (α = .76), and (c) Managing Environment (α = .84). The majority of the observed relations between these 3 subscales, and the SRSI-SR, student motivation beliefs, and student mathematics grades were statistically significant and in the small to medium range. After controlling for various student variables and motivation indices of parental involvement, 2 SRSI-PRS factors (Managing Behavior and Learning, Maladaptive Regulatory Behaviors) reliably predicted students' achievement in their mathematics course. This study provides initial support for the validity and reliability of the SRSI-PRS and underscores the advantages of obtaining parental ratings of students' SRL behaviors. (c) 2015 APA, all rights reserved).

Aging and loading rate effects on the mechanical behavior of equine bone

NASA Astrophysics Data System (ADS)

Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

2008-06-01

Whether due to a sporting accident, high-speed impact, fall, or other catastrophic event, the majority of clinical bone fractures occur under dynamic loading conditions. However, although extensive research has been performed on the quasi-static fracture and mechanical behavior of bone to date, few high-quality studies on the fracture behavior of bone at high strain rates have been performed. Therefore, many questions remain regarding the material behavior, including not only the loading-rate-dependent response of bone, but also how this response varies with age. In this study, tests were performed on equine femoral bone taken post-mortem from donors 6 months to 28 years of age. Quasi-static and dynamic tests were performed to determine the fracture toughness and compressive mechanical behavior as a function of age at varying loading rates. Fracture paths were then analyzed using scanning confocal and scanning-electron microscopy techniques to assess the role of various microstructural features on toughening mechanisms.

Embedding Multilevel Survival Analysis of Dyadic Social Interaction in Structural Equation Models: Hazard Rates as Both Outcomes and Predictors

PubMed Central

Snyder, James

2014-01-01

Objective Demonstrate multivariate multilevel survival analysis within a larger structural equation model. Test the 3 hypotheses that when confronted by a negative parent, child rates of angry, sad/fearful, and positive emotion will increase, decrease, and stay the same, respectively, for antisocial compared with normal children. This same pattern will predict increases in future antisocial behavior. Methods Parent–child dyads were videotaped in the fall of kindergarten in the laboratory and antisocial behavior ratings were obtained in the fall of kindergarten and third grade. Results Kindergarten antisocial predicted less child sad/fear and child positive but did not predict child anger given parent negative. Less child positive and more child neutral given parent negative predicted increases in third-grade antisocial behavior. Conclusions The model is a useful analytic tool for studying rates of social behavior. Lack of positive affect or excess neutral affect may be a new risk factor for child antisocial behavior. PMID:24133296

Treatment Acceptability of Behavioral Interventions for Children: An Assessment by Mothers of Children with Disruptive Behavior Disorders.

ERIC Educational Resources Information Center

Jones, Melanie L.; Eyberg, Sheila M.; Adams, Christina D.; Boggs, Stephen R.

1998-01-01

Study assesses the acceptability of six child-management interventions as rated by mothers (N=20) of children referred for treatment for a disruptive-behavior disorder. Positive reinforcement was rated as a more acceptable treatment than response time, time-out, differential attention, overcorrection, and spanking. Results validate findings of…

The Kindergarten Academic and Behavior Readiness Screener: The Utility of Single-Item Teacher Ratings of Kindergarten Readiness

ERIC Educational Resources Information Center

Stormont, Melissa; Herman, Keith C.; Reinke, Wendy M.; King, Kathleen R.; Owens, Sarah

2015-01-01

The purpose of the study was to explore the effectiveness of a brief, feasible, and cost-effective universal screener for kindergarten readiness. The study examined whether teacher ratings of kindergarteners' academic, behavioral, and overall readiness at the beginning of the year were predictive of academic, emotional, and behavioral outcomes at…

The Relationship between Behavior Ratings and Concurrent and Subsequent Mental and Motor Performance in Toddlers Born at Extremely Low Birth Weight

ERIC Educational Resources Information Center

Messinger, Daniel; Lambert, Brittany; Bauer, Charles R.; Bann, Carla M.; Hamlin-Smith, Kasey; Das, Abhik

2010-01-01

When predicting child developmental outcomes, reliance on children's scores on measures of developmental functioning alone might mask more subtle behavioral difficulties, especially in children with developmental risk factors. The current study examined predictors and stability of examiner behavior ratings and their association with concurrent and…

Confirmatory Factor Analysis of the "Preschool Behavioral and Emotional Rating Scale" (PreBERS) with Preschool Children with Disabilities

ERIC Educational Resources Information Center

Cress, Cynthia J.; Synhorst, Lori; Epstein, Michael H.; Allen, Elizabeth

2012-01-01

The "Preschool Behavioral and Emotional Rating Scale" (PreBERS) is a standardized, norm-referenced instrument that assesses emotional and behavioral strengths of preschool children. This study investigated whether the PreBERS four-factor structure (i.e., emotional regulation, school readiness, social confidence, and family involvement)…

Effects of Weighted Vests on Classroom Behavior for Children with Autism and Cognitive Impairments

ERIC Educational Resources Information Center

Hodgetts, Sandra; Magill-Evans, Joyce; Misiaszek, John

2011-01-01

This randomized controlled single-case study investigated the effects of weighted vests for 10 children with autism in a classroom setting. Blinded observers rated targeted behaviors through video taken during structured table-top activities typically part of the classroom routine. Blinded teachers rated each child's behavior with the Conners'…

Technical Analysis of the Disruptive Behavior Rating Scale--Second Edition--Teacher Version

ERIC Educational Resources Information Center

Erford, Bradley T.; Clark, Kelly

2011-01-01

The reliability and validity of scores on the Disruptive Behavior Rating Scale-second edition-teacher version (DBRS-II-T) was analyzed. The DBRS-II-T was designed to assess teacher observations of students referred for behavioral difficulties. The five-factor model fit the data poorly, but convergent and diagnostic validities were excellent.…

Parent Use of DRI on High Rate Disruptive Behavior: Direct and Collateral Benefits.

ERIC Educational Resources Information Center

Friman, Patrick C.; Altman, Karl

1990-01-01

This study evaluates parental use of differential reinforcement of other and/or incompatible behavior to treat high-rate disruptive behavior in a severely retarded four-year-old boy. A withdrawal experimental design was used. Intervention effectively reduced instances of toy chewing and throwing, while appropriate toy play and ability to remain…

Frame of Reference Rater Training Issues: Recall, Time and Behavior Observation Training.

ERIC Educational Resources Information Center

Roch, Sylvia G.; O'Sullivan, Brian J.

2003-01-01

Graduate students were trained as raters either using frame of reference (FOR, n=220, behavior observation training (BOT, n=21), or performance appraisal (controls, n=21). They rated videotaped lecturers twice. FOR increased number of behaviors recalled; FOR and BOT improved recall quality. FOR improved rating accuracy even after 2 weeks.…

Experimental analysis of precursors to severe problem behavior.

PubMed

Fritz, Jennifer N; Iwata, Brian A; Hammond, Jennifer L; Bloom, Sarah E

2013-01-01

Some individuals engage in both mild and severe forms of problem behavior. Research has shown that when mild behaviors precede severe behaviors (i.e., the mild behaviors serve as precursors), they can (a) be maintained by the same source of reinforcement as severe behavior and (b) reduce rates of severe behavior observed during assessment. In Study 1, we developed an objective checklist to identify precursors via videotaped trials for 16 subjects who engaged in problem behavior and identified at least 1 precursor for every subject. In Study 2, we conducted separate functional analyses of precursor and severe problem behaviors for 8 subjects, and obtained correspondence between outcomes in 7 cases. In Study 3, we evaluated noncontingent reinforcement schedule thinning plus differential reinforcement of alternative behavior to reduce precursors, increase appropriate behavior, and maintain low rates of severe behavior during 3 treatment analyses for 2 subjects. Results showed that this treatment strategy was effective for behaviors maintained by positive and negative reinforcement. © Society for the Experimental Analysis of Behavior.

On the evolution of harming and recognition in finite panmictic and infinite structured populations

PubMed Central

Lehmann, Laurent; Feldman, Marcus W.; Rousset, François

2010-01-01

Natural selection may favor two very different types of social behaviors that have costs in vital rates (fecundity and/or survival) to the actor: helping behaviors, which increase the vital rates of recipients, and harming behaviors, which reduce the vital rates of recipients. While social evolutionary theory has mainly dealt with helping behaviors, competition for limited resources creates ecological conditions where an actor may benefit from expressing behaviors that reduce the vital rates of neighbours. This may occur if the reduction in vital rates decreases the intensity of competition experienced by the actor or that experienced by its offspring. Here, we explore the joint evolution of neutral recognition markers and marker-based costly conditional harming whereby actors express harming, conditional on actor and recipient bearing different conspicuous markers. We do so for two complementary demographic scenarios: finite panmictic and infinite structured populations. We find that marker-based conditional harming can evolve under a large range of recombination rates and group sizes under both finite panmictic and infinite structured populations. Direct comparison with results for the evolution of marker-based conditional helping reveals that, if everything else is equal, marker-based conditional harming is often more likely to evolve than marker-based conditional. PMID:19624725

The relation of low-level prenatal lead exposure to behavioral indicators of attention in Inuit infants in Arctic Quebec.

PubMed

Plusquellec, P; Muckle, G; Dewailly, E; Ayotte, P; Jacobson, S W; Jacobson, J L

2007-01-01

The aim of this study was to investigate the association between prenatal exposure to lead (Pb) and several aspects of behavioral function during infancy through examiner ratings and behavioral coding of video recordings. The sample consisted of 169 11-month-old Inuit infants from Arctic Quebec. Umbilical cord and maternal blood samples were used to document prenatal exposure to Pb. Average blood Pb levels were 4.6 mug/dL and 5.9 mug/dL in cord and maternal samples respectively. The Behavior Rating Scales (BRS) from the Bayley Scales of Infant Development (BSID-II) were used to assess behavior. Attention was assessed through the BRS and behavioral coding of video recordings taken during the administration of the BSID-II. Whereas the examiner ratings of behaviors detected very few associations with prenatal Pb exposure, cord blood Pb concentrations were significantly related to the direct observational measures of infant attention, after adjustment for confounding variables. These data provide evidence that increasing the specificity and the precision of the behavioral assessment has considerable potential for improving our ability to detect low-to-moderate associations between neurotoxicants, such Pb and infant behavior.

Suicide Behaviors in Adult Inpatients with Mental Disorders in Beijing, China

PubMed Central

Gao, Qi; Fan, Hua; Di, Fei; Xia, Xue; Long, Haiying; Zhu, Huiping

2017-01-01

Background: This study examined the tendency and suicidal behavior rates of Chinese adult inpatients with different types of mental disorders from 2010 to 2015. The aim was to provide some interesting clues for further studies. Methods: Adult patients with mental disorders who were hospitalized in Beijing Anding hospital from 1 January 2010 to 31 December 2015 were included. Chi-square tests were used to compare the difference among inpatients with mental disorders by gender and year. Frequency, trend and suicidal behavior rates of inpatients with mental disorders were graphed. Results: A total of 17,244 psychiatric adult inpatients were included in our study. About 53.2% of the inpatients had mood disorders, followed by schizophrenia, which accounted for 34.6%. The proportion of female inpatients with mental disorders was larger than that of males (52.6% to 47.4%). Of the total, 3296 psychiatric inpatients were recognized as having suicidal behaviors. The rate of suicidal behavior among all inpatients was 19.1%, and it varied over the years. The suicidal behavior rate of female inpatients with mood disorders was much higher than that of the corresponding male inpatients. Conclusions: The presence of suicidal behavior varied among people with different types of mental disorders. For each type of mental illness, identifying the risk of specific suicide behavior would help tailor-make preventive efforts accordingly. PMID:28273823

[Effectiveness of cognitive-behavioral therapy in childhood anxiety disorders in a university psychiatric outpatient clinic].

PubMed

Goletz, Hildegard; Yang, Young-Im; Suhr-Dachs, Lydia; Walter, Daniel; Döpfner, Manfred

2013-07-01

Only few studies have examined whether the efficacy of cognitive-behavioral therapy for childhood anxiety disorders as demonstrated in randomized controlled trials (RCTs) generalizes to clinical practice. This study examines the effectiveness of cognitive-behavioral therapy for juvenile anxiety disorders under routine care conditions in a university-based psychiatric outpatient clinic. 92 children and adolescents with parent-ratings regarding anxiety and comorbid symptoms and 61 children and adolescents with self-ratings regarding anxiety and comorbid symptoms were treated with cognitive-behavioral interventions. Pre/post mean comparisons, effect sizes, and the clinical significance of changes in symptoms were examined. The effect size for reduction of anxiety symptoms was .81 for children whose parents had completed the rating scale and .79 for children who had filled in a self-rating scale. Effect sizes for reduction of comorbid symptoms varied between .37 and .84 for parent ratings and between .21 and .62 for self-ratings. The percentage of children and adolescents who achieved clinically significant improvements in anxiety symptoms was 55.1 % according to the parent ratings and 65.7 % according to the children's self-ratings. More than 50 % of parents and children reported clinically significant improvements in comorbid symptoms. Significant reductions in both anxiety and comorbid symptoms were demonstrated over the course of cognitive-behavioral therapy of juvenile anxiety disorders in a university psychiatric outpatient clinic. The effect sizes for anxiety symptoms were found to be comparable to the effect sizes reported in RCTs. Similarly, clinically significant improvements were as frequent as the rates of remission of anxiety symptoms reported in RCTs.

Psychometric Properties of the Behavioral Inhibition Questionnaire in Preschool Children

PubMed Central

Kim, Jiyon; Klein, Daniel N.; Olino, Thomas M.; Dyson, Margaret W.; Dougherty, Lea R.; Durbin, C. Emily

2012-01-01

We examined the psychometric properties of the Behavioral Inhibition Questionnaire (BIQ), a rating scale for children’s behavioral inhibition (BI). Parent and teacher ratings, parent interviews, and laboratory observations were obtained for 495 preschoolers. Confirmatory factor analysis yielded six factors, each reflecting the BIQ’s subscales, and all loading onto a second-order general dimension. Model fit was acceptable for parent ratings, but only marginal for teacher ratings. The convergent and discriminant validity of the BIQ was examined by using a multitrait multimethod approach. Results indicate that the BIQ displays evidence of reliability and validity that can complement observational paradigms. PMID:21999378

Preventing Negative Behaviors Among Elementary-School Students Through Enhancing Students’ Social-Emotional and Character Development

PubMed Central

Snyder, Frank J.; Acock, Alan C.; Vuchinich, Samuel; Beets, Michael W.; Washburn, Isaac J.; Flay, Brian R.

2013-01-01

Purpose Examine the effects of a comprehensive, school-wide social-emotional and character development program using a positive youth development perspective. Specifically, we examined a mediation mechanism whereby positive academic-related behaviors mediated the intervention effects on substance use, violence, and sexual activity. Design Matched-pair, cluster-randomized, controlled design. Setting Twenty (10 intervention and 10 control) racially/ethnically diverse schools in Hawaii. Subjects Elementary-aged students (N = 1784) from grade 5. Intervention The Positive Action program. Measures Students self-reported their academic behaviors, together with their substance use, violence, and voluntary sexual activity; teachers rated students’ academic behaviors, substance use, and violence. Analysis Structural equation modeling. Results Students attending intervention schools reported significantly better academic behavior (B = .273, SE = .039, p < .001) and significantly less substance use (B = −.970, SE = .292, p < .01, incidence-rate ratio [IRR] = .379), violence (B = −1.410, SE = .296, p < .001, IRR= .244), and sexual activity (B = − 2.415, SE = .608, p < .001, odds ratio = .089); boys reported more negative behaviors than girls. Intervention effects on student-reported substance use, violence, and sexual activity were mediated by positive academic behavior. Teacher reports corroborated these results, with rated academic behavior partially mediating the effects of the intervention on rated negative behaviors. Conclusion This study (1) provides evidence that adds insight into one mechanism through which a social-emotional and character development program affects negative outcomes and (2) supports social-emotional and character development and positive youth development perspectives that posit that focusing on youths’ assets may reduce negative behaviors. PMID:23470183

Parent-rated emotional-behavioral and executive functioning in childhood epilepsy.

PubMed

Kavanaugh, Brian C; Scarborough, Vanessa Ramos; Salorio, Cynthia F

2015-01-01

The present study examined clinical and demographic risk factors associated with parent-rated emotional-behavioral and executive functioning in children and adolescents with epilepsy. The medical records of 152 children and adolescents with epilepsy referred for neuropsychological evaluation were reviewed. Results indicated that the sample displayed significantly elevated symptoms across the emotional-behavioral and executive domains assessed. Executive functioning and behavioral symptoms had the highest rates of clinically elevated scores, with lowest rates of elevated scores in internalizing and externalizing emotional problems. Only 34% of those participants with clinically significant emotional-behavioral or executive functioning difficulties had a history of psychological or counseling services, highlighting the underserved mental health needs of this population. In regard to clinical factors, the majority of seizure-related variables were not associated with emotional-behavioral or executive functioning. However, the frequency of seizures (i.e., seizure status) was associated with behavioral regulation aspects of executive functioning, and the age at evaluation was associated with externalizing problems and behavioral symptoms. Family psychiatric history (with the exception of ADHD) was associated with all domains of executive and emotional-behavioral functioning. In summary, emotional-behavioral and executive functioning difficulties frequently co-occur with seizures in childhood epilepsy, with both seizure-related and demographic factors contributing to the presentation of such neurobehavioral comorbidities. The present findings provide treatment providers of childhood epilepsy with important information to assist in better identifying children and adolescents who may be at risk for neurobehavioral comorbidities and may benefit from intervention. Copyright © 2014 Elsevier Inc. All rights reserved.

Client and clinician-rated characteristics of problem gamblers with and without history of gambling-related illegal behaviors.

PubMed

Ellis, Jennifer D; Lister, Jamey J; Struble, Cara A; Cairncross, Molly; Carr, Meagan M; Ledgerwood, David M

2018-03-12

Individuals with gambling disorder are at an elevated risk for engaging in gambling-related illegal behaviors. The present study examined client (N = 88) and clinician ratings (N = 30) of client characteristics associated with a history of gambling-related illegal behaviors. We also examined client characteristics associated with history of arrest for a gambling-related crime. Gambling-related illegal behaviors and arrest were common (57.3% and 23.9%, respectively) in the present sample. Clients of younger age, and those with greater gambling-related financial consequences, lifetime alcohol problems, impulsivity, mood symptoms, and daily living role difficulties were more likely to report gambling-related illegal behaviors. Clients who had been arrested for a gambling-related crime were more likely to report daily living and role functioning difficulties and lifetime alcohol problems. Clinicians rated clients with a history of gambling-related illegal behaviors and/or gambling-related arrests as more impulsive, and clinicians also endorsed higher rates of treatment failure among these clients. Both client and clinician report suggested that clients with a history of illegal behaviors may have a variety of comorbid problems that may be a focus of clinical intervention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valderrama, B.; Henderson, H.B.; Gan, J.

2015-04-01

Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO 2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporationmore » regimes are present in UO 2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO 2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.« less

Identifying instructional tasks that occasion problem behaviors and assessing the effects of student versus teacher choice among these tasks.

PubMed

Vaughn, B J; Horner, R H

1997-01-01

Levels of problem behavior were assessed when 4 students with severe disabilities received instruction on preferred versus nonpreferred tasks and when tasks of each type were chosen by the teacher rather than by the student. In Phase 1, interview and direct observation assessments were conducted to identify relative preferences for academic tasks. In Phase 2, the effects of these lower preference and higher preference tasks on the rate of problem behavior were evaluated using a multielement design. The results showed that lower preference tasks were associated with higher rates of problem behaviors and that students, when given a choice, consistently selected the tasks that had been identified through interview and direct observation as higher preference. In Phase 3, we assessed whether allowing the students to choose between pairs of lower preference tasks or between pairs of higher preference tasks reduced problem behavior relative to a condition in which the teacher selected the same tasks. For 2 of 4 students, the rates of problem behavior were lower when students (rather than the teacher) selected the lower preference activity. Higher preference tasks for 3 students were associated with relatively low rates of problem behavior regardless of whether the student or the teacher selected the task.

Fitness, fatness, cognition, behavior, and academic achievement among overweight children: Do cross-sectional associations correspond to exercise trial outcomes?

PubMed Central

Davis, Catherine L.; Cooper, Stephanie

2011-01-01

Background This study examined associations of fitness and fatness with cognitive processes, academic achievement, and behavior, independent of demographic factors, at the baseline of an exercise trial. Methods Overweight, sedentary but otherwise healthy 7–11 year olds (N=170) participated in a study of health, cognition and achievement in the Augusta, GA area from 2003–2006. Children underwent evaluations of fatness and fitness, psychological assessments of cognition and academic achievement, and behavior ratings by parents and teachers. Partial correlations examined associations of fitness and fatness with cognitive and achievement scores and behavior ratings, controlling for demographic factors. Results Fitness was associated with better cognition, achievement and behavior, and fatness with worse scores. Specifically, executive function, mathematics and reading achievement, and parent ratings of child behavior were related to fitness and fatness. Teacher ratings were related to fitness. Conclusion These results extend prior studies by providing reliable, standardized measures of cognitive processes, achievement, and behavior in relation to detailed measures of fitness and fatness. However, cross-sectional associations do not necessarily indicate that improving one factor, such as fatness or fitness, will result in improvements in factors that were associated with it. Thus, randomized clinical trials are necessary to determine the effects of interventions. PMID:21281668

Fitness, fatness, cognition, behavior, and academic achievement among overweight children: do cross-sectional associations correspond to exercise trial outcomes?

PubMed

Davis, Catherine L; Cooper, Stephanie

2011-06-01

This study examined associations of fitness and fatness with cognitive processes, academic achievement, and behavior, independent of demographic factors, at the baseline of an exercise trial. Overweight, sedentary but otherwise healthy 7-11 year olds (N=170) participated in a study of health, cognition and achievement in the Augusta, GA area from 2003-2006. Children underwent evaluations of fatness and fitness, psychological assessments of cognition and academic achievement, and behavior ratings by parents and teachers. Partial correlations examined associations of fitness and fatness with cognitive and achievement scores and behavior ratings, controlling for demographic factors. Fitness was associated with better cognition, achievement and behavior, and fatness with worse scores. Specifically, executive function, mathematics and reading achievement, and parent ratings of child behavior were related to fitness and fatness. Teacher ratings were related to fitness. These results extend prior studies by providing reliable, standardized measures of cognitive processes, achievement, and behavior in relation to detailed measures of fitness and fatness. However, cross-sectional associations do not necessarily indicate that improving one factor, such as fatness or fitness, will result in improvements in factors that were associated with it. Thus, randomized clinical trials are necessary to determine the effects of interventions. Copyright © 2011. Published by Elsevier Inc.

Studies of the physical, yield and failure behavior of aliphatic polyketones

NASA Astrophysics Data System (ADS)

Karttunen, Nicole Renee

This thesis describes an investigation into the multiaxial yield and failure behavior of an aliphatic polyketone terpolymer. The behavior is studied as a function of: stress state, strain rate, temperature, and sample processing conditions. Results of this work include: elucidation of the behavior of a recently commercialized polymer, increased understanding of the effects listed above, insight into the effects of processing conditions on the morphology of the polyketone, and a description of yield strength of this material as a function of stress state, temperature, and strain rate. The first portion of work focuses on the behavior of a set of samples that are extruded under "common" processing conditions. Following this reference set of tests, the effect of testing this material at different temperatures is studied. A total of four different temperatures are examined. In addition, the effect of altering strain rate is examined. Testing is performed under pseudo-strain rate control at constant nominal octahedral shear strain rate for each failure envelope. A total of three different rates are studied. An extension of the first portion of work involves modeling the yield envelope. This is done by combining two approaches: continuum level and molecular level. The use of both methods allows the description of the yield envelope as a function of stress state, strain rate and temperature. The second portion of work involves the effects of processing conditions. For this work, additional samples are extruded with different shear and thermal histories than the "standard" material. One set of samples is processed with shear rates higher and lower than the standard. A second set is processed at higher and lower cooling rates than the standard. In order to understand the structural cause for changes in behavior with processing conditions, morphological characterization is performed on these samples. In particular, the effect on spherulitic structure is important. Residual stresses are also determined to be important to the behavior of the samples. Finally, an investigation into the crystalline structure of a family of aliphatic polyketones is performed. The effects of side group concentration and size are described.

Heuristic Processes in Ratings of Leader Behavior: Assessing Item-Induced Availability Biases.

ERIC Educational Resources Information Center

Binning, John F.; Fernandez, Guadalupe

Since observers' memory-based ratings of organizational phenomena provide data in research and decision-making contexts, bias in observers' judgments must be examined. A study was conducted to explore the extent to which leader behavior ratings are more generally biased by the availability heuristic. The availability heuristic is operative when a…

The Role of Children's Ethnicity in the Relationship between Teacher Ratings of Attention-Deficit/Hyperactivity Disorder and Observed Classroom Behavior

ERIC Educational Resources Information Center

Epstein, Jeffrey N.; Willoughby, Michael; Valencia, Elvia Y.; Tonev, Simon T.; Abikoff, Howard B.; Arnold, L. Eugene; Hinshaw, Stephen P.

2005-01-01

Significant ethnic differences have been consistently documented on attention-deficit/hyperactivity disorder (ADHD) teacher rating scales. Whether these ethnic differences result from a teacher rating bias or reflect actual classroom behavior patterns is unknown. Ethnic differences between Caucasian and African American (AA) elementary…

Impact of Children's Identified Disability Status on Parent and Teacher Behavior Ratings

ERIC Educational Resources Information Center

Schwehr, Ethan; Bocanegra, Joel O.; Kwon, Kyongboon; Sheridan, Susan M.

2014-01-01

This study was an examination of the possible influence of a child's pre-identified disability on parent and teacher behavior ratings and whether a child's disability status affected parent ratings, when controlling for parenting stress. The sample included 206 kindergarten through third grade students and their teachers and parents from a…

Measuring Competence and Dysfunction in Preschool Children: Source Agreement and Component Structure

ERIC Educational Resources Information Center

Klyce, Daniel; Conger, Anthony J.; Conger, Judith Cohen; Dumas, Jean E.

2011-01-01

Agreement between parents and teachers on ratings of three domains of behaviors exhibited by preschool children and the structural relations between these domains were measured. Parents and teachers rated the behaviors of a socioeconomically diverse sample of 610 children; ratings were obtained from parents at three time points and from teachers…

Base Rates, Contingencies, and Prediction Behavior

ERIC Educational Resources Information Center

Kareev, Yaakov; Fiedler, Klaus; Avrahami, Judith

2009-01-01

A skew in the base rate of upcoming events can often provide a better cue for accurate predictions than a contingency between signals and events. The authors study prediction behavior and test people's sensitivity to both base rate and contingency; they also examine people's ability to compare the benefits of both for prediction. They formalize…

Perceptions of coping behaviors by persons with cancer and health care providers.

PubMed

Merluzzi, T V; Martinez Sanchez, M A

1997-09-01

We studied perceptions of the importance and difficulty of coping behaviors, from the perspectives of cancer patients (n = 33) and health care providers (i.e. nursing and technical personnel, n = 24). They rated the importance and difficulty of 43 behaviors that correspond to six domains of coping with cancer. Generally, ratings of importance were similar for both patients and providers. However, patients rated the domains of Coping with Treatment Related Side Effects and Seeking Support as less important than staff. Ratings of difficulty were quite divergent. Patients perceived coping as less difficult than the medical staff in the following domains: Maintenance of Activity and Independence, Coping With Treatment-Related Side-Effects, Accepting Cancer/Maintaining Positive Attitude, and Seeking Support. These differences in difficulty ratings between patients and health care providers may reflect distinct perspectives or schemas about coping. That is, patients may hold 'positive illusions' about their coping capacity and, therefore, rate coping as less difficult. Health care providers may overestimate patients' distress and, therefore, underestimate patients' coping capacity. An understanding of these different perspectives may assist medical staff in fostering self-efficacy expectations for coping behaviors.

Associations between informant ratings of personality disorder traits, self-reports of personality, and directly observed behavior.

PubMed

Kaurin, Aleksandra; Sauerberger, Kyle S; Funder, David C

2018-03-02

Diagnoses of personality disorders (PD) must rely on judgments of observers-either clinicians or acquaintances-because personality disorders are primarily defined in terms of maladaptive interpersonal behavior. Little is known, however, about how closely acquaintances' judgments of PD traits relate to self-reports of theoretically relevant Big Five traits or directly observed behavioral outcomes in interpersonal situations. The present study examines associations between judgments of the 10 PD traits provided by close acquaintances, self-reports of PD-relevant Big Five personality traits, and observed interpersonal behaviors across three different three-person laboratory interactions (i.e., unstructured chat, cooperative task, competitive game). The sample consisted of 256 undergraduate students (130 females; M age  = 19.83, SD = 1.25). Four unacquainted observers independently rated participants' behaviors from video recordings. In line with previous work, informant reports of PD traits demonstrate strong convergent validity with relevant self-reported Big Five traits (as identified by Lynam & Widiger, 2001). Directly observed behavior is meaningfully associated with acquaintances' judgments and self-reports of PD-relevant traits, and the associations between these judgments and behavior are strongest for traits associated with histrionic and schizoid PD. Vector correlations between behavioral profiles associated with informant and self-reports show that both assessments have similar behavioral correlates. Associations between PD trait ratings and behavior appeared to differ as a function of gender, with males showing more and stronger correlations. Informants' ratings of PD traits are impressively accurate, converging both with self-reports of relevant traits and directly observed interpersonal behavior. Therefore, a comprehensive understanding of PDs and associated traits can be augmented by information from multiple acquaintances who have the opportunity to observe how an individual interacts with others on a daily basis across diverse contexts. © 2018 Wiley Periodicals, Inc.

Scaling behavior of online human activity

NASA Astrophysics Data System (ADS)

Zhao, Zhi-Dan; Cai, Shi-Min; Huang, Junming; Fu, Yan; Zhou, Tao

2012-11-01

The rapid development of the Internet technology enables humans to explore the web and record the traces of online activities. From the analysis of these large-scale data sets (i.e., traces), we can get insights about the dynamic behavior of human activity. In this letter, the scaling behavior and complexity of human activity in the e-commerce, such as music, books, and movies rating, are comprehensively investigated by using the detrended fluctuation analysis technique and the multiscale entropy method. Firstly, the interevent time series of rating behaviors of these three types of media show similar scaling properties with exponents ranging from 0.53 to 0.58, which implies that the collective behaviors of rating media follow a process embodying self-similarity and long-range correlation. Meanwhile, by dividing the users into three groups based on their activities (i.e., rating per unit time), we find that the scaling exponents of the interevent time series in the three groups are different. Hence, these results suggest that a stronger long-range correlations exist in these collective behaviors. Furthermore, their information complexities vary in the three groups. To explain the differences of the collective behaviors restricted to the three groups, we study the dynamic behavior of human activity at the individual level, and find that the dynamic behaviors of a few users have extremely small scaling exponents associated with long-range anticorrelations. By comparing the interevent time distributions of four representative users, we can find that the bimodal distributions may bring forth the extraordinary scaling behaviors. These results of the analysis of the online human activity in the e-commerce may not only provide insight into its dynamic behaviors but may also be applied to acquire potential economic interest.

The integration of depressive behaviors and cardiac dysfunction during an operational measure of depression: investigating the role of negative social experiences in an animal model.

PubMed

Grippo, Angela J; Moffitt, Julia A; Sgoifo, Andrea; Jepson, Amanda J; Bates, Suzanne L; Chandler, Danielle L; McNeal, Neal; Preihs, Kristin

2012-01-01

There is a bidirectional association between depression and cardiovascular disease. The neurobiological mechanisms underlying this association may involve an inability to cope with disrupted social bonds. This study investigated in an animal model the integration of depressive behaviors and cardiac dysfunction after a disrupted social bond and during an operational measure of depression, relative to the protective effects of intact social bonds. Depressive behaviors in the forced swim test and continuous electrocardiographic parameters were measured in 14 adult, female socially monogamous prairie voles (rodents), after 4 weeks of social pairing or isolation. After social isolation, animals exhibited (all values are mean ± standard error of the mean; isolated versus paired, respectively) increased heart rate (416 ± 14 versus 370 ± 14 bpm, p < .05) and reduced heart rate variability (3.3 ± 0.2 versus 3.9 ± 0.2 ln(ms(2))). During the forced swim test, isolated animals exhibited greater helpless behavior (immobility = 106 ± 11 versus 63 ± 11 seconds, p < .05), increased heart rate (530 ± 22 versus 447 ± 15 bpm, p < .05), reduced heart rate variability (1.8 ± 0.4 versus 2.7 ± 0.2 ln(ms(2)), p < .05), and increased arrhythmias (arrhythmic burden score = 181 ± 46 versus 28 ± 12, p < .05). The display of depressive behaviors during an operational measure of depression is coupled with increased heart rate, reduced heart rate variability, and increased arrhythmias, indicative of dysfunctional behavioral and physiological stress coping abilities as a function of social isolation. In contrast, social pairing with a sibling is behaviorally protective and cardioprotective. The present results can provide insight into a possible social mechanism underlying the association between depression and cardiovascular disease in humans.

Reduction in children's symptoms of attention deficit hyperactivity disorder and oppositional defiant disorder during individual tutoring as compared with classroom instruction.

PubMed

Strayhorn, Joseph M; Bickel, Donna D

2002-08-01

Children who display symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in classrooms are reputed to display fewer symptoms in one-on-one interaction. We tested this hypothesis with children who received tutoring for reading and behavior problems. We selected 30 children whose teacher-rated ADHD symptoms fit a pattern consistent with DSM criteria for the diagnosis. Teachers rated the frequency of symptoms in classrooms before and after tutoring. Tutors rated the frequency of the same behaviors during individual tutoring sessions. Children's ADHD symptoms, as well as oppositional symptoms, were significantly lower in the tutoring sessions than in the classrooms. The effect sizes for the difference between behavior in classrooms and in individual tutoring ranged from 0.7 to 2.5 standard deviations. These effect sizes appear as large as those reported for the effect of stimulant medication on ADHD symptoms. All 30 children at preintervention fit the pattern for ADHD using teachers' ratings of classroom behavior; 87% of them did not meet those DSM criteria using tutors' ratings of behavior in individual sessions. The confound of different raters for the two different settings must be resolved by another study with a new design.

Evolution of the Novalux extended cavity surface-emitting semiconductor laser (NECSEL)

NASA Astrophysics Data System (ADS)

McInerney, John G.

2016-03-01

Novalux Inc was an enterprise founded by Aram Mooradian in 1998 to commercialise a novel electrically pumped vertical extended cavity semiconductor laser platform, initially aiming to produce pump lasers for optical fiber telecommunication networks. Following successful major investment in 2000, the company developed a range of single- and multi-mode 980 nm pump lasers emitting from 100-500 mW with excellent beam quality and efficiency. This rapid development required solution of several significant problems in chip and external cavity design, substrate and DBR mirror optimization, thermal engineering and mode selection. Output coupling to single mode fiber was exceptional. Following the collapse of the long haul telecom market in late 2001, a major reorientation of effort was undertaken, initially to develop compact 60-100 mW hybrid monolithically integrated pumplets for metro/local amplified networks, then to frequency-doubled blue light emitters for biotech, reprographics and general scientific applications. During 2001-3 I worked at Novalux on a career break from University College Cork, first as R&D Director managing a small group tasked with producing new capabilities and product options based on the NECSEL platform, including high power, pulsed and frequency doubled versions, then in 2002 as Director of New Product Realization managing the full engineering team, leading the transition to frequency doubled products.

Compartmentalized Metabolic Engineering for Artemisinin Biosynthesis and Effective Malaria Treatment by Oral Delivery of Plant Cells

PubMed Central

Malhotra, Karan; Subramaniyan, Mayavan; Rawat, Khushboo; Kalamuddin, Md.; Qureshi, M. Irfan; Malhotra, Pawan; Mohmmed, Asif; Cornish, Katrina; Daniell, Henry; Kumar, Shashi

2017-01-01

Artemisinin is highly effective against drug-resistant malarial parasites, which affects nearly half of the global population and kills >500 000 people each year. The primary cost of artemisinin is the very expensive process used to extract and purify the drug from Artemisia annua. Elimination of this apparently unnecessary step will make this potent antimalarial drug affordable to the global population living in endemic regions. Here we reported the oral delivery of a non-protein drug artemisinin biosynthesized (~0.8 mg/g dry weight) at clinically meaningful levels in tobacco by engineering two metabolic pathways targeted to three different cellular compartments (chloroplast, nucleus, and mitochondria). The doubly transgenic lines showed a three-fold enhancement of isopentenyl pyrophosphate, and targeting AACPR, DBR2, and CYP71AV1 to chloroplasts resulted in higher expression and an efficient photo-oxidation of dihydroartemisinic acid to artemisinin. Partially purified extracts from the leaves of transgenic tobacco plants inhibited in vitro growth progression of Plasmodium falciparum-infected red blood cells. Oral feeding of whole intact plant cells bioencapsulating the artemisinin reduced the parasitemia levels in challenged mice in comparison with commercial drug. Such novel synergistic approaches should facilitate low-cost production and delivery of artemisinin and other drugs through metabolic engineering of edible plants. PMID:27773616

[INVITED] Surface plasmon cavities on optical fiber end-facets for biomolecule and ultrasound detection

NASA Astrophysics Data System (ADS)

Yang, Tian; He, Xiaolong; Zhou, Xin; Lei, Zeyu; Wang, Yalin; Yang, Jie; Cai, De; Chen, Sung-Liang; Wang, Xueding

2018-05-01

Integrating surface plasmon resonance (SPR) devices upon single-mode fiber (SMF) end facets renders label-free sensing systems that have a simple dip-and-read configuration, a small form factor, high compatibility with fiber-optic techniques, and invasive testing capability. Such devices are not only low cost replacement of current equipments in centralized laboratories, but also highly desirable for opening paths to new applications of label-free optical sensing technologies, such as point-of-care immunological tests and intravascular ultrasound imaging. In this paper, we explain the requirements and challenges for such devices from the perspectives of biomolecule and ultrasound detection applications. In such a context, we review our recent work on SMF end-facet SPR cavities. This include a glue-and-strip fabrication method to transfer a nano-patterned thin gold film to the SMF end-facet with high yield, high quality and high alignment precision, the designs of distributed Bragg reflector (DBR) and distributed feedback (DFB) SPR cavities that couple efficiently with the SMF guided mode and reach quality factors of over 100, and the preliminary results for biomolecule interaction sensing and ultrasound detection. The particular advantages and potential values of these devices have been discussed, in terms of sensitivity, data reliability, reproducibility, bandwidth, etc.

ATG18 and FAB1 are involved in dehydration stress tolerance in Saccharomyces cerevisiae.

PubMed

López-Martínez, Gema; Margalef-Català, Mar; Salinas, Francisco; Liti, Gianni; Cordero-Otero, Ricardo

2015-01-01

Recently, different dehydration-based technologies have been evaluated for the purpose of cell and tissue preservation. Although some early results have been promising, they have not satisfied the requirements for large-scale applications. The long experience of using quantitative trait loci (QTLs) with the yeast Saccharomyces cerevisiae has proven to be a good model organism for studying the link between complex phenotypes and DNA variations. Here, we use QTL analysis as a tool for identifying the specific yeast traits involved in dehydration stress tolerance. Three hybrids obtained from stable haploids and sequenced in the Saccharomyces Genome Resequencing Project showed intermediate dehydration tolerance in most cases. The dehydration resistance trait of 96 segregants from each hybrid was quantified. A smooth, continuous distribution of the anhydrobiosis tolerance trait was found, suggesting that this trait is determined by multiple QTLs. Therefore, we carried out a QTL analysis to identify the determinants of this dehydration tolerance trait at the genomic level. Among the genes identified after reciprocal hemizygosity assays, RSM22, ATG18 and DBR1 had not been referenced in previous studies. We report new phenotypes for these genes using a previously validated test. Finally, our data illustrates the power of this approach in the investigation of the complex cell dehydration phenotype.