Fabrication and characterization of a 0.5-mm lutetium oxyorthosilicate detector array for high-resolution PET applications.

PubMed

Stickel, Jennifer R; Qi, Jinyi; Cherry, Simon R

2007-01-01

With the increasing use of in vivo imaging in mouse models of disease, there are many interesting applications that demand imaging of organs and tissues with submillimeter resolution. Though there are other contributing factors, the spatial resolution in small-animal PET is still largely determined by the detector pixel dimensions. In this work, a pair of lutetium oxyorthosilicate (LSO) arrays with 0.5-mm pixels was coupled to multichannel photomultiplier tubes and evaluated for use as high-resolution PET detectors. Flood histograms demonstrated that most crystals were clearly identifiable. Energy resolution varied from 22% to 38%. The coincidence timing resolution was 1.42-ns full width at half maximum (FWHM). The intrinsic spatial resolution was 0.68-mm FWHM as measured with a 30-gauge needle filled with (18)F. The improvement in spatial resolution in a tomographic setting is demonstrated using images of a line source phantom reconstructed with filtered backprojection and compared with images obtained from 2 dedicated small-animal PET scanners. Finally, a projection image of the mouse foot is shown to demonstrate the application of these 0.5-mm LSO detectors to a biologic task. A pair of highly pixelated LSO detections has been constructed and characterized for use as high-spatial-resolution PET detectors. It appears that small-animal PET systems capable of a FWHM spatial resolution of 600 microm or less are feasible and should be pursued.

Assessing the Likelihood of Transmission of Candidatus Liberibacter solanacearum to Carrot by Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae)

PubMed Central

Munyaneza, Joseph E.; Mustafa, Tariq; Fisher, Tonja W.; Sengoda, Venkatesan G.; Horton, David R.

2016-01-01

‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-limited bacterium that severely affects important Solanaceae and Apiaceae crops, including potato, tomato, pepper, tobacco, carrot and celery. This bacterium is transmitted to solanaceous species by potato psyllid, Bactericera cockerelli, and to Apiaceae by carrot psyllids, including Trioza apicalis and Bactericera trigonica. Five haplotypes of Lso have so far been described, two are associated with solanaceous species and potato psyllids, whereas the other three are associated with carrot and celery crops and carrot psyllids. Little is known about cross-transmission of Lso to carrot by potato psyllids or to potato by carrot psyllids. Thus, the present study assessed whether potato psyllid can transmit Lso to carrot and whether Lso haplotypes infecting solanaceous species can also infect carrot and lead to disease symptom development. In addition, the stylet probing behavior of potato psyllid on carrot was assessed using electropenetrography (EPG) technology to further elucidate potential Lso transmission to Apiaceae by this potato insect pest. Results showed that, while potato psyllids survived on carrot for several weeks when confined on the plants under controlled laboratory and field conditions, the insects generally failed to infect carrot plants with Lso. Only three of the 200 carrot plants assayed became infected with Lso and developed characteristic disease symptoms. Lso infection in the symptomatic carrot plants was confirmed by polymerase chain reaction assay and Lso in the carrots was determined to be of the haplotype B, which is associated with solanaceous species. EPG results further revealed that potato psyllids readily feed on carrot xylem but rarely probe into the phloem tissue, explaining why little to no Lso infection occurred during the controlled laboratory and field cage transmission trials. Results of our laboratory and field transmission studies, combined with our EPG results, suggest that the risk of Lso infection and spread between psyllid-infested solanaceous and Apiaceae crops is likely to be negligible under normal field conditions. PMID:27525703

Dual sensitivity of inferior colliculus neurons to ITD in the envelopes of high-frequency sounds: experimental and modeling study

PubMed Central

Wang, Le; Devore, Sasha; Delgutte, Bertrand

2013-01-01

Human listeners are sensitive to interaural time differences (ITDs) in the envelopes of sounds, which can serve as a cue for sound localization. Many high-frequency neurons in the mammalian inferior colliculus (IC) are sensitive to envelope-ITDs of sinusoidally amplitude-modulated (SAM) sounds. Typically, envelope-ITD-sensitive IC neurons exhibit either peak-type sensitivity, discharging maximally at the same delay across frequencies, or trough-type sensitivity, discharging minimally at the same delay across frequencies, consistent with responses observed at the primary site of binaural interaction in the medial and lateral superior olives (MSO and LSO), respectively. However, some high-frequency IC neurons exhibit dual types of envelope-ITD sensitivity in their responses to SAM tones, that is, they exhibit peak-type sensitivity at some modulation frequencies and trough-type sensitivity at other frequencies. Here we show that high-frequency IC neurons in the unanesthetized rabbit can also exhibit dual types of envelope-ITD sensitivity in their responses to SAM noise. Such complex responses to SAM stimuli could be achieved by convergent inputs from MSO and LSO onto single IC neurons. We test this hypothesis by implementing a physiologically explicit, computational model of the binaural pathway. Specifically, we examined envelope-ITD sensitivity of a simple model IC neuron that receives convergent inputs from MSO and LSO model neurons. We show that dual envelope-ITD sensitivity emerges in the IC when convergent MSO and LSO inputs are differentially tuned for modulation frequency. PMID:24155013

Physiological models of the lateral superior olive

PubMed Central

2017-01-01

In computational biology, modeling is a fundamental tool for formulating, analyzing and predicting complex phenomena. Most neuron models, however, are designed to reproduce certain small sets of empirical data. Hence their outcome is usually not compatible or comparable with other models or datasets, making it unclear how widely applicable such models are. In this study, we investigate these aspects of modeling, namely credibility and generalizability, with a specific focus on auditory neurons involved in the localization of sound sources. The primary cues for binaural sound localization are comprised of interaural time and level differences (ITD/ILD), which are the timing and intensity differences of the sound waves arriving at the two ears. The lateral superior olive (LSO) in the auditory brainstem is one of the locations where such acoustic information is first computed. An LSO neuron receives temporally structured excitatory and inhibitory synaptic inputs that are driven by ipsi- and contralateral sound stimuli, respectively, and changes its spike rate according to binaural acoustic differences. Here we examine seven contemporary models of LSO neurons with different levels of biophysical complexity, from predominantly functional ones (‘shot-noise’ models) to those with more detailed physiological components (variations of integrate-and-fire and Hodgkin-Huxley-type). These models, calibrated to reproduce known monaural and binaural characteristics of LSO, generate largely similar results to each other in simulating ITD and ILD coding. Our comparisons of physiological detail, computational efficiency, predictive performances, and further expandability of the models demonstrate (1) that the simplistic, functional LSO models are suitable for applications where low computational costs and mathematical transparency are needed, (2) that more complex models with detailed membrane potential dynamics are necessary for simulation studies where sub-neuronal nonlinear processes play important roles, and (3) that, for general purposes, intermediate models might be a reasonable compromise between simplicity and biological plausibility. PMID:29281618

Continuous depth-of-interaction encoding using phosphor-coated scintillators.

PubMed

Du, Huini; Yang, Yongfeng; Glodo, Jarek; Wu, Yibao; Shah, Kanai; Cherry, Simon R

2009-03-21

We investigate a novel detector using a lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium-aluminum-gallium oxide:cerium, Y(3)(Al,Ga)(5)O(12):Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of approximately 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5 x 1.5 x 20 mm(3) LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 x 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be approximately 8 mm for this 2 cm thick array.

Continuous Depth-of-Interaction Encoding Using Phosphor-Coated Scintillators

PubMed Central

Du, Huini; Yang, Yongfeng; Glodo, Jarek; Wu, Yibao; Shah, Kanai; Cherry, Simon R.

2009-01-01

We investigate a novel detector using lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium aluminum gallium oxide:cerium, Y3(Al,Ga)5O12:Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of ∼ 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5×1.5×20 mm3 LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 by 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be ∼8 mm for this 2 cm thick array. PMID:19258685

Broadly wavelength tunable acousto-optically Q-switched Tm:Lu2SiO5 laser.

PubMed

Feng, T; Yang, K; Zhao, S; Zhao, J; Qiao, W; Li, T; Zheng, L; Xu, J

2014-09-20

A broadly wavelength tunable acousto-optically Q-switched Tm:Lu2SiO5 (Tm:LSO) laser is presented for the first time, to our best knowledge. The emission wavelength was tuned in a broad spectral region over 111 nm ranging from 1959 to 2070 nm. A shortest pulse duration of 345 ns with beam quality of M(2)≤1.65 was obtained at pulse repetition frequency (PRF) of 1 kHz, corresponding to a maximum single pulse energy of 0.26 mJ and peak power of 0.75 kW. The experimental results indicated that Tm:LSO crystal has outstanding potential for obtaining broadly wavelength tunable and low-PRF laser pulses at 2 μm.

Multiplex real-time PCR for detection, identification and quantification of 'Candidatus Liberibacter solanacearum' in potato plants with zebra chip.

PubMed

Li, Wenbin; Abad, Jorge A; French-Monar, Ronald D; Rascoe, John; Wen, Aimin; Gudmestad, Neil C; Secor, Gary A; Lee, Ing-Ming; Duan, Yongping; Levy, Laurene

2009-07-01

The new Liberibacter species, 'Candidatus Liberibacter solanacearum' (Lso) recently associated with potato/tomato psyllid-transmitted diseases in tomato and capsicum in New Zealand, was found to be consistently associated with a newly emerging potato zebra chip (ZC) disease in Texas and other southwestern states in the USA. A species-specific primer LsoF was developed for both quantitative real-time PCR (qPCR) and conventional PCR (cPCR) to detect and quantify Lso in infected samples. In multiplex qPCR, a plant cytochrome oxidase (COX)-based probe-primer set was used as a positive internal control for host plants, which could be used to reliably access the DNA extraction quality and to normalize qPCR data for accurate quantification of the bacterial populations in environment samples. Neither the qPCR nor the cPCR using the primer and/or probe sets with LsoF reacted with other Liberibacter species infecting citrus or other potato pathogens. The low detection limit of the multiplex qPCR was about 20 copies of the target 16S rDNA templates per reaction for field samples. Lso was readily detected and quantified in various tissues of ZC-affected potato plants collected from fields in Texas. A thorough but uneven colonization of Lso was revealed in various tissues of potato plants. The highest Lso populations were about 3x10(8) genomes/g tissue in the root, which were 3-order higher than those in the above-ground tissues of potato plants. The Lso bacterial populations were normally distributed across the ZC-affected potato plants collected from fields in Texas, with 60% of ZC-affected potato plants harboring an average Lso population from 10(5) to 10(6) genomes/g tissue, 4% of plants hosting above 10(7) Lso genomes/g tissue, and 8% of plants holding below 10(3) Lso genomes/g tissue. The rapid, sensitive, specific and reliable multiplex qPCR showed its potential to become a powerful tool for early detection and quantification of the new Liberibacter species associated with potato ZC, and will be very useful for the potato quarantine programs and seed potato certification programs to ensure the availability of clean seed potato stocks and also for epidemiological studies on the disease.

Validation of a Simulation Model of Intrinsic Lutetium-176 Activity in LSO-Based Preclinical PET Systems

NASA Astrophysics Data System (ADS)

McIntosh, Bryan

The LSO scintillator crystal commonly used in PET scanners contains a low level of intrinsic radioactivity due to a small amount of Lu-176. This is not usually a concern in routine scanning but can become an issue in small animal imaging, especially when imaging low tracer activity levels. Previously there had been no systematic validation of simulations of this activity; this thesis discusses the validation of a GATE model of intrinsic Lu-176 against results from a bench-top pair of detectors and a Siemens Inveon preclinical PET system. The simulation results matched those from the bench-top system very well, but did not agree as well with results from the complete Inveon system due to a drop-off in system sensitivity at low energies that was not modelled. With this validation the model can now be used with confidence to predict the effects of Lu-176 activity in future PET systems.

Detection of high energy muons with sub-20 ps timing resolution using L(Y)SO crystals and SiPM readout

NASA Astrophysics Data System (ADS)

Benaglia, A.; Gundacker, S.; Lecoq, P.; Lucchini, M. T.; Para, A.; Pauwels, K.; Auffray, E.

2016-09-01

Precise timing capability will be a key aspect of particle detectors at future high energy colliders, as the time information can help in the reconstruction of physics events at the high collision rate expected there. Other than being used in detectors for PET, fast scintillating crystals coupled to compact Silicon Photomultipliers (SiPMs) constitute a versatile system that can be exploited to realize an ad-hoc timing device to be hosted in a larger high energy physics detector. In this paper, we present the timing performance of LYSO:Ce and LSO:Ce codoped 0.4% Ca crystals coupled to SiPMs, as measured with 150 GeV muons at the CERN SPS H2 extraction line. Small crystals, with lengths ranging from 5 mm up to 30 mm and transverse size of 2 × 2mm2 or 3 × 3mm2 , were exposed to a 150 GeV muon beam. SiPMs from two different companies (Hamamatsu and FBK) were used to detect the light produced in the crystals. The best coincidence time resolution value of (14.5 ± 0.5) ps , corresponding to a single-detector time resolution of about 10 ps, is demonstrated for 5 mm long LSO:Ce,Ca crystals coupled to FBK SiPMs, when time walk corrections are applied.

Effects of reflector and crystal surface on the performance of a depth-encoding PET detector with dual-ended readout

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

Ren, Silin; Yang, Yongfeng, E-mail: yfyang@ucdavis.edu; Cherry, Simon R.

Purpose: Depth encoding detectors are required to improve the spatial resolution and spatial resolution uniformity of small animal positron emission tomography (PET) scanners, as well as dedicated breast and brain scanners. Depth of interaction (DOI) can be measured by using dual-ended readout of lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiodes. Inter-crystal reflectors and crystal surface treatments play important roles in determining the performance of dual-ended detectors. In this paper, the authors evaluated five LSO arrays made with three different intercrystal reflectors and with either polished or unpolished crystal surfaces. Methods: The crystal size in all arrays was 1.5more » mm, which is typical of the detector size used in small animal and dedicated breast scanners. The LSO arrays were measured with dual-ended readout and were compared in terms of flood histogram, energy resolution, and DOI resolution performance. Results: The four arrays using enhanced specular reflector (ESR) and Toray reflector provided similar quality flood histograms and the array using Crystal Wrap reflector gave the worst flood histogram. The two arrays using ESR reflector provided the best energy resolution and the array using Crystal Wrap reflector yielded the worst energy resolution. All arrays except the polished ESR array provided good DOI resolution ranging from 1.9 mm to 2.9 mm. DOI resolution improved as the gradient in light collection efficiency with depth (GLCED) increased. The geometric mean energies were also calculated for these dual-ended readout detectors as an alternative to the conventional summed total energy. It was shown that the geometric mean energy is advantageous in that it provides more uniform photopeak amplitude at different depths for arrays with high GLCED, and is beneficial in event selection by allowing a fixed energy window independent of depth. A new method of DOI calculation that improved the linearity of DOI ratio vs depth and simplifies the DOI calibration procedure also was developed and tested. Conclusions: The results of these studies provide useful guidance in selecting the proper reflectors and crystal surface treatments when LSO arrays are used for high-resolution PET applications in small animal scanners or dedicated breast and brain scanners.« less

Increase of “Candidatus Liberibacter solanacearum” titer in aging tomato leaves and pyrosequencing analyses of endophyte populations

USDA-ARS?s Scientific Manuscript database

This project studied changes in titer of “Candidatus Liberibacter solanacearum” (Lso) in tomato leaves of different cultivars with the goal of searching for factors associated with Lso enrichment. Lso titers, as monitored by qPCR, were observed to increase in tomato leaf cultures, which involved mai...

Characterization of host plant resistance to zebra chip disease from species-derived potato genotypes and the identification of new sources of zebra chip resistance.

PubMed

Rashidi, Mahnaz; Novy, Richard G; Wallis, Christopher M; Rashed, Arash

2017-01-01

'Candidatus Liberibacter solanacearum' (Lso), an uncultivable phloem-limited phytopathogenic bacteria, is known to be associated with Zebra Chip disease (ZC), which represents a major threat to potato production in the US and elsewhere. This pathogen is transmitted by the phloem-feeding potato psyllid, Bactericera cockerelli Sulc (Hem. Triozidae). Currently, there are no reports of resistance to ZC in cultivated potatoes. This greenhouse study was conducted to evaluate Lso transmission success and the susceptibility of 11 potato breeding clones, representing diverge genetic background, to ZC, in relation to a susceptible commercial cultivar, Russet Burbank. Individual plants were exposed to two Lso-positive potato psyllids for 48 hours. The percentage of successful Lso transmission varied across the evaluated genotypes ranging between 7 and 57%. Freshly-cut and fried tubers showed significant variation in ZC symptom severity among the breeding clones, with several genotypes expressing relative tolerance when compared to Russet Burbank. None of the evaluated clones showed statistically lower Lso titers than Russet Burbank with the exception of one genotype in the second year of the study. However, the presence of a non-significant relationship between average symptom severity and Lso titer indicated variations in phenotypic responses (i.e. tolerance) to Lso existed among evaluated breeding lines. Breeding clones A07781-3LB, A07781-4LB and A07781-10LB had relatively lower Lso titer (low susceptibility) and tuber symptom expression (high tolerance) among the tested genotypes. As these three clones represent full siblings, the observed effects could be indicative of the presence of a genetic basis for resistance/tolerance to ZC. Findings provide a better understanding of resistance/tolerance to ZC, and contribute to continued efforts in breeding for resistance to this disease.

Characterization of host plant resistance to zebra chip disease from species-derived potato genotypes and the identification of new sources of zebra chip resistance

PubMed Central

Rashidi, Mahnaz; Novy, Richard G.; Wallis, Christopher M.

2017-01-01

‘Candidatus Liberibacter solanacearum’ (Lso), an uncultivable phloem-limited phytopathogenic bacteria, is known to be associated with Zebra Chip disease (ZC), which represents a major threat to potato production in the US and elsewhere. This pathogen is transmitted by the phloem-feeding potato psyllid, Bactericera cockerelli Sulc (Hem. Triozidae). Currently, there are no reports of resistance to ZC in cultivated potatoes. This greenhouse study was conducted to evaluate Lso transmission success and the susceptibility of 11 potato breeding clones, representing diverge genetic background, to ZC, in relation to a susceptible commercial cultivar, Russet Burbank. Individual plants were exposed to two Lso-positive potato psyllids for 48 hours. The percentage of successful Lso transmission varied across the evaluated genotypes ranging between 7 and 57%. Freshly-cut and fried tubers showed significant variation in ZC symptom severity among the breeding clones, with several genotypes expressing relative tolerance when compared to Russet Burbank. None of the evaluated clones showed statistically lower Lso titers than Russet Burbank with the exception of one genotype in the second year of the study. However, the presence of a non-significant relationship between average symptom severity and Lso titer indicated variations in phenotypic responses (i.e. tolerance) to Lso existed among evaluated breeding lines. Breeding clones A07781-3LB, A07781-4LB and A07781-10LB had relatively lower Lso titer (low susceptibility) and tuber symptom expression (high tolerance) among the tested genotypes. As these three clones represent full siblings, the observed effects could be indicative of the presence of a genetic basis for resistance/tolerance to ZC. Findings provide a better understanding of resistance/tolerance to ZC, and contribute to continued efforts in breeding for resistance to this disease. PMID:28832618

The effects of a three-week use of lumbosacral orthoses on trunk muscle activity and on the muscular response to trunk perturbations

PubMed Central

2010-01-01

Background The effects of lumbosacral orthoses (LSOs) on neuromuscular control of the trunk are not known. There is a concern that wearing LSOs for a long period may adversely alter muscle control, making individuals more susceptible to injury if they discontinue wearing the LSOs. The purpose of this study was to document neuromuscular changes in healthy subjects during a 3-week period while they regularly wore a LSO. Methods Fourteen subjects wore LSOs 3 hrs a day for 3 weeks. Trunk muscle activity prior to and following a quick force release (trunk perturbation) was measured with EMG in 3 sessions on days 0, 7, and 21. A longitudinal, repeated-measures, factorial design was used. Muscle reflex response to trunk perturbations, spine compression force, as well as effective trunk stiffness and damping were dependent variables. The LSO, direction of perturbation, and testing session were the independent variables. Results The LSO significantly (P < 0.001) increased the effective trunk stiffness by 160 Nm/rad (27%) across all directions and testing sessions. The number of antagonist muscles that responded with an onset activity was significantly reduced after 7 days of wearing the LSO, but this difference disappeared on day 21 and is likely not clinically relevant. The average number of agonist muscles switching off following the quick force release was significantly greater with the LSO, compared to without the LSO (P = 0.003). Conclusions The LSO increased trunk stiffness and resulted in a greater number of agonist muscles shutting-off in response to a quick force release. However, these effects did not result in detrimental changes to the neuromuscular function of trunk muscles after 3 weeks of wearing a LSO 3 hours a day by healthy subjects. PMID:20609255

Solid State Recrystallization of Single Crystal Ce:LSO Scintillator Crystals for High Resolution Detectors

DTIC Science & Technology

2012-06-01

this report. The property measurements that have been focused on were the assessment of density ( Archimedes ). grain structure {optical and SEM...Scintillator", Materials Letters 60 1960-1963 (2006) [15] J.S. Reed, Forming Processes, Chapter 20 in Introduction to the Principles of Ceramic

Timing properties of phosphor-coated polished LSO crystals.

PubMed

Schmall, Jeffrey P; Roncali, Emilie; Berg, Eric; Viswanath, Varsha; Du, Junwei; Cherry, Simon R

2014-08-07

This study investigates a time-of-flight (TOF)-depth-of-interaction (DOI) detector design for positron emission tomography (PET), based on phosphor-coated lutetium oxyorthosilicate (LSO) scintillator crystals coupled to fast single channel photomultiplier tubes. Interaction of the scintillation light with the phosphor coating changes the pulse shape in a depth-dependent manner. 3 × 3 × 10 mm(3) LSO scintillation crystals with polished surfaces were characterized, with and without phosphor coating, to assess DOI capability and timing properties. Two different phosphor coating geometries were studied: coating of the top surface of the crystal, and the top plus half of the crystal sides. There was negligible depth dependency in the decay time when coating only the top surface, however there was a ∼10 ns difference in end-to-end decay time when coating the top plus half of the crystal sides, sufficient to support the use of three DOI bins (3.3 mm DOI bin width). The rise time of the half-coated phosphor crystal was slightly faster at all depths, compared to uncoated crystals, however the signal amplitude was lower. Phosphor coating resulted in depth-dependent photopeak positions with an energy resolution of 13.7%, at a depth of 1 mm, and 15.3%, at a depth of 9 mm, for the half-coated crystal. Uncoated LSO crystals showed no change in photopeak position as a function of depth, with an energy resolution of 10.4%. The head-on coincidence timing resolution (CTR) of two uncoated LSO crystals was 287 ps using constant fraction discrimination for time pick-off. With phosphor coating, the CTR of the top-coated crystal was 314 ps, compared to 384 ps for the half-coated crystal. We demonstrate that the trade-off between timing resolution and DOI resolution can be controlled by the phosphor coating geometry. Here we present preliminary results demonstrating that good DOI resolution can be achieved with only a modest 26% degradation in CTR.

6 Mcps photon-counting X-ray computed tomography system using a 25 mm/s-scan linear LSO-MPPC detector and its application to gadolinium imaging

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Oda, Yasuyuki; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sugimura, Shigeaki; Endo, Haruyuki; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2011-12-01

6 Mcps photon counting was carried out using a detector consisting of a 1.0 mm-thick LSO [Lu 2(SiO 4)O] single-crystal scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The maximum count rate was 6 Mcps (mega counts per second) at a tube voltage of 100 kV and a tube current of 0.91 mA. Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage controller, the LSO-MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0°, and photon-counting CT was accomplished using gadolinium-based contrast media.

Interaural Phase and Level Difference Sensitivity in Low-Frequency Neurons in the Lateral Superior Olive

PubMed Central

Tollin, Daniel J.; Yin, Tom C. T.

2006-01-01

The lateral superior olive (LSO) is believed to encode differences in sound level at the two ears, a cue for azimuthal sound location. Most high-frequency-sensitive LSO neurons are binaural, receiving inputs from both ears. An inhibitory input from the contralateral ear, via the medial nucleus of the trapezoid body (MNTB), and excitatory input from the ipsilateral ear enable level differences to be encoded. However, the classical descriptions of low-frequency-sensitive neurons report primarily monaural cells with no contralateral inhibition. Anatomical and physiological evidence, however, shows that low-frequency LSO neurons receive low-frequency inhibitory input from ipsilateral MNTB, which in turn receives excitatory input from the contralateral cochlear nucleus and low-frequency excitatory input from the ipsilateral cochlear nucleus. Therefore, these neurons would be expected to be binaural with contralateral inhibition. Here, we re-examined binaural interaction in low-frequency (less than ~3 kHz) LSO neurons and phase locking in the MNTB. Phase locking to low-frequency tones in MNTB and ipsilaterally driven LSO neurons with frequency sensitivities < 1.2 kHz was enhanced relative to the auditory nerve. Moreover, most low-frequency LSO neurons exhibited contralateral inhibition: ipsilaterally driven responses were suppressed by raising the level of the contralateral stimulus; most neurons were sensitive to interaural time delays in pure tone and noise stimuli such that inhibition was nearly maximal when the stimuli were presented to the ears in-phase. The data demonstrate that low-frequency LSO neurons of cat are not monaural and can exhibit contralateral inhibition like their high-frequency counterparts. PMID:16291937

Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation.

PubMed

van Dam, Herman T; Borghi, Giacomo; Seifert, Stefan; Schaart, Dennis R

2013-05-21

Digital silicon photomultiplier (dSiPM) arrays have favorable characteristics for application in monolithic scintillator detectors for time-of-flight positron emission tomography (PET). To fully exploit these benefits, a maximum likelihood interaction time estimation (MLITE) method was developed to derive the time of interaction from the multiple time stamps obtained per scintillation event. MLITE was compared to several deterministic methods. Timing measurements were performed with monolithic scintillator detectors based on novel dSiPM arrays and LSO:Ce,0.2%Ca crystals of 16 × 16 × 10 mm(3), 16 × 16 × 20 mm(3), 24 × 24 × 10 mm(3), and 24 × 24 × 20 mm(3). The best coincidence resolving times (CRTs) for pairs of identical detectors were obtained with MLITE and measured 157 ps, 185 ps, 161 ps, and 184 ps full-width-at-half-maximum (FWHM), respectively. For comparison, a small reference detector, consisting of a 3 × 3 × 5 mm(3) LSO:Ce,0.2%Ca crystal coupled to a single pixel of a dSiPM array, was measured to have a CRT as low as 120 ps FWHM. The results of this work indicate that the influence of the optical transport of the scintillation photons on the timing performance of monolithic scintillator detectors can at least partially be corrected for by utilizing the information contained in the spatio-temporal distribution of the collection of time stamps registered per scintillation event.

Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation

NASA Astrophysics Data System (ADS)

van Dam, Herman T.; Borghi, Giacomo; Seifert, Stefan; Schaart, Dennis R.

2013-05-01

Digital silicon photomultiplier (dSiPM) arrays have favorable characteristics for application in monolithic scintillator detectors for time-of-flight positron emission tomography (PET). To fully exploit these benefits, a maximum likelihood interaction time estimation (MLITE) method was developed to derive the time of interaction from the multiple time stamps obtained per scintillation event. MLITE was compared to several deterministic methods. Timing measurements were performed with monolithic scintillator detectors based on novel dSiPM arrays and LSO:Ce,0.2%Ca crystals of 16 × 16 × 10 mm3, 16 × 16 × 20 mm3, 24 × 24 × 10 mm3, and 24 × 24 × 20 mm3. The best coincidence resolving times (CRTs) for pairs of identical detectors were obtained with MLITE and measured 157 ps, 185 ps, 161 ps, and 184 ps full-width-at-half-maximum (FWHM), respectively. For comparison, a small reference detector, consisting of a 3 × 3 × 5 mm3 LSO:Ce,0.2%Ca crystal coupled to a single pixel of a dSiPM array, was measured to have a CRT as low as 120 ps FWHM. The results of this work indicate that the influence of the optical transport of the scintillation photons on the timing performance of monolithic scintillator detectors can at least partially be corrected for by utilizing the information contained in the spatio-temporal distribution of the collection of time stamps registered per scintillation event.

A nonstationary Poisson point process describes the sequence of action potentials over long time scales in lateral-superior-olive auditory neurons.

PubMed

Turcott, R G; Lowen, S B; Li, E; Johnson, D H; Tsuchitani, C; Teich, M C

1994-01-01

The behavior of lateral-superior-olive (LSO) auditory neurons over large time scales was investigated. Of particular interest was the determination as to whether LSO neurons exhibit the same type of fractal behavior as that observed in primary VIII-nerve auditory neurons. It has been suggested that this fractal behavior, apparent on long time scales, may play a role in optimally coding natural sounds. We found that a nonfractal model, the nonstationary dead-time-modified Poisson point process (DTMP), describes the LSO firing patterns well for time scales greater than a few tens of milliseconds, a region where the specific details of refractoriness are unimportant. The rate is given by the sum of two decaying exponential functions. The process is completely specified by the initial values and time constants of the two exponentials and by the dead-time relation. Specific measures of the firing patterns investigated were the interspike-interval (ISI) histogram, the Fano-factor time curve (FFC), and the serial count correlation coefficient (SCC) with the number of action potentials in successive counting times serving as the random variable. For all the data sets we examined, the latter portion of the recording was well approximated by a single exponential rate function since the initial exponential portion rapidly decreases to a negligible value. Analytical expressions available for the statistics of a DTMP with a single exponential rate function can therefore be used for this portion of the data. Good agreement was obtained among the analytical results, the computer simulation, and the experimental data on time scales where the details of refractoriness are insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced Excitatory Connectivity and Disturbed Sound Processing in the Auditory Brainstem of Fragile X Mice.

PubMed

Garcia-Pino, Elisabet; Gessele, Nikodemus; Koch, Ursula

2017-08-02

Hypersensitivity to sounds is one of the prevalent symptoms in individuals with Fragile X syndrome (FXS). It manifests behaviorally early during development and is often used as a landmark for treatment efficacy. However, the physiological mechanisms and circuit-level alterations underlying this aberrant behavior remain poorly understood. Using the mouse model of FXS ( Fmr1 KO ), we demonstrate that functional maturation of auditory brainstem synapses is impaired in FXS. Fmr1 KO mice showed a greatly enhanced excitatory synaptic input strength in neurons of the lateral superior olive (LSO), a prominent auditory brainstem nucleus, which integrates ipsilateral excitation and contralateral inhibition to compute interaural level differences. Conversely, the glycinergic, inhibitory input properties remained unaffected. The enhanced excitation was the result of an increased number of cochlear nucleus fibers converging onto one LSO neuron, without changing individual synapse properties. Concomitantly, immunolabeling of excitatory ending markers revealed an increase in the immunolabeled area, supporting abnormally elevated excitatory input numbers. Intrinsic firing properties were only slightly enhanced. In line with the disturbed development of LSO circuitry, auditory processing was also affected in adult Fmr1 KO mice as shown with single-unit recordings of LSO neurons. These processing deficits manifested as an increase in firing rate, a broadening of the frequency response area, and a shift in the interaural level difference function of LSO neurons. Our results suggest that this aberrant synaptic development of auditory brainstem circuits might be a major underlying cause of the auditory processing deficits in FXS. SIGNIFICANCE STATEMENT Fragile X Syndrome (FXS) is the most common inheritable form of intellectual impairment, including autism. A core symptom of FXS is extreme sensitivity to loud sounds. This is one reason why individuals with FXS tend to avoid social interactions, contributing to their isolation. Here, a mouse model of FXS was used to investigate the auditory brainstem where basic sound information is first processed. Loss of the Fragile X mental retardation protein leads to excessive excitatory compared with inhibitory inputs in neurons extracting information about sound levels. Functionally, this elevated excitation results in increased firing rates, and abnormal coding of frequency and binaural sound localization cues. Imbalanced early-stage sound level processing could partially explain the auditory processing deficits in FXS. Copyright © 2017 the authors 0270-6474/17/377403-17$15.00/0.

Monte Carlo study on the imaging performance of powder Lu2SiO5:Ce phosphor screens under x-ray excitation: comparison with Gd2O2S:Tb screens.

PubMed

Liaparinos, Panagiotis F; Kandarakis, Ioannis S; Cavouras, Dionisis A; Delis, Harry B; Panayiotakis, George S

2007-05-01

Lu2SiO5: Ce (LSO) scintillator is a relatively new luminescent material which has been successfully applied in positron emission tomography systems. Since it has been recently commercially available in powder form, it could be of value to investigate its performance for use in x-ray projection imaging as both physical and scintillating properties indicate a promising material for such applications. In the present study, a custom and validated Monte Carlo simulation code was used in order to examine the performance of LSO, under diagnostic radiology (mammography and general radiography) conditions. The Monte Carlo code was based on a model using Mie scattering theory for the description of light attenuation. Imaging characteristics, related to image brightness, spatial resolution and noise of LSO screens were predicted using only physical parameters of the phosphor. The overall performance of LSO powder phosphor screens was investigated in terms of the: (i) quantum detection efficiency (ii) emitted K-characteristic radiation (iii) luminescence efficiency (iv) modulation transfer function (v) Swank factor and (vi) zero-frequency detective quantum efficiency [DQE(0)]. Results were compared to the traditional rare-earth Gd2O2S:Tb (GOS) phosphor material. The relative luminescence efficiency of LSO phosphor was found inferior to that of GOS. This is due to the lower intrinsic conversion efficiency of LSO (0.08 instead of 0.15 of GOS) and the relatively high light extinction coefficient mext of this phosphor (0.239 mircom(-1) instead of 0.218 /microm(-1) for GOS). However, the property of increased light extinction combined with the rather sharp angular distribution of scattered light photons (anisotropy factor g=0.624 for LSO instead of 0.494 for GOS) reduce lateral light spreading and improve spatial resolution. In addition, LSO screens were found to exhibit better x-ray absorption as well as higher signal to noise transfer properties in the energy range from 18 keV up to 50.2 keV (e.g. DQE(0)=0.62 at 18 keV and for 34 mg/cm2, instead of 0.58 for GOS). The results indicate that certain optical properties of LSO (optical extinction coefficient, scattering anisotropy factor) combined with the relatively high x-ray coefficients, make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray projection imaging detectors.

A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

PubMed

Wu, Heyu; Tai, Yuan-Chuan

2011-09-07

To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

Zebra chip development during storage: cause for concern?

USDA-ARS?s Scientific Manuscript database

Zebra chip disease is associated with infections by ‘Candidatus Liberibacter solanacearum’ (Lso), a bacterium spread by the potato psyllid Bactericera cockerelli. A major concern of the potato industry is the likelihood that Lso could cause asymptomatic infections prior to placement of tubers in col...

Principal cells of the brainstem's interaural sound level detector are temporal differentiators rather than integrators.

PubMed

Franken, Tom P; Joris, Philip X; Smith, Philip H

2018-06-14

The brainstem's lateral superior olive (LSO) is thought to be crucial for localizing high-frequency sounds by coding interaural sound level differences (ILD). Its neurons weigh contralateral inhibition against ipsilateral excitation, making their firing rate a function of the azimuthal position of a sound source. Since the very first in vivo recordings, LSO principal neurons have been reported to give sustained and temporally integrating 'chopper' responses to sustained sounds. Neurons with transient responses were observed but largely ignored and even considered a sign of pathology. Using the Mongolian gerbil as a model system, we have obtained the first in vivo patch clamp recordings from labeled LSO neurons and find that principal LSO neurons, the most numerous projection neurons of this nucleus, only respond at sound onset and show fast membrane features suggesting an importance for timing. These results provide a new framework to interpret previously puzzling features of this circuit. © 2018, Franken et al.

Impact of event positioning algorithm on performance of a whole-body PET scanner using one-to-one coupled detectors

NASA Astrophysics Data System (ADS)

Surti, S.; Karp, J. S.

2018-03-01

The advent of silicon photomultipliers (SiPMs) has introduced the possibility of increased detector performance in commercial whole-body PET scanners. The primary advantage of these photodetectors is the ability to couple a single SiPM channel directly to a single pixel of PET scintillator that is typically 4 mm wide (one-to-one coupled detector design). We performed simulation studies to evaluate the impact of three different event positioning algorithms in such detectors: (i) a weighted energy centroid positioning (Anger logic), (ii) identifying the crystal with maximum energy deposition (1st max crystal), and (iii) identifying the crystal with the second highest energy deposition (2nd max crystal). Detector simulations performed with LSO crystals indicate reduced positioning errors when using the 2nd max crystal positioning algorithm. These studies are performed over a range of crystal cross-sections varying from 1  ×  1 mm2 to 4  ×  4 mm2 as well as crystal thickness of 1 cm to 3 cm. System simulations were performed for a whole-body PET scanner (85 cm ring diameter) with a long axial FOV (70 cm long) and show an improvement in reconstructed spatial resolution for a point source when using the 2nd max crystal positioning algorithm. Finally, we observe a 30-40% gain in contrast recovery coefficient values for 1 and 0.5 cm diameter spheres when using the 2nd max crystal positioning algorithm compared to the 1st max crystal positioning algorithm. These results show that there is an advantage to implementing the 2nd max crystal positioning algorithm in a new generation of PET scanners using one-to-one coupled detector design with lutetium based crystals, including LSO, LYSO or scintillators that have similar density and effective atomic number as LSO.

Evaluation of PET Imaging Resolution Using 350 mu{m} Pixelated CZT as a VP-PET Insert Detector

NASA Astrophysics Data System (ADS)

Yin, Yongzhi; Chen, Ximeng; Li, Chongzheng; Wu, Heyu; Komarov, Sergey; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2014-02-01

A cadmium-zinc-telluride (CZT) detector with 350 μm pitch pixels was studied in high-resolution positron emission tomography (PET) imaging applications. The PET imaging system was based on coincidence detection between a CZT detector and a lutetium oxyorthosilicate (LSO)-based Inveon PET detector in virtual-pinhole PET geometry. The LSO detector is a 20 ×20 array, with 1.6 mm pitches, and 10 mm thickness. The CZT detector uses ac 20 ×20 ×5 mm substrate, with 350 μm pitch pixelated anodes and a coplanar cathode. A NEMA NU4 Na-22 point source of 250 μm in diameter was imaged by this system. Experiments show that the image resolution of single-pixel photopeak events was 590 μm FWHM while the image resolution of double-pixel photopeak events was 640 μm FWHM. The inclusion of double-pixel full-energy events increased the sensitivity of the imaging system. To validate the imaging experiment, we conducted a Monte Carlo (MC) simulation for the same PET system in Geant4 Application for Emission Tomography. We defined LSO detectors as a scanner ring and 350 μm pixelated CZT detectors as an insert ring. GATE simulated coincidence data were sorted into an insert-scanner sinogram and reconstructed. The image resolution of MC-simulated data (which did not factor in positron range and acolinearity effect) was 460 μm at FWHM for single-pixel events. The image resolutions of experimental data, MC simulated data, and theoretical calculation are all close to 500 μm FWHM when the proposed 350 μm pixelated CZT detector is used as a PET insert. The interpolation algorithm for the charge sharing events was also investigated. The PET image that was reconstructed using the interpolation algorithm shows improved image resolution compared with the image resolution without interpolation algorithm.

Altered gene expression of epigenetic modifying enzymes in response to dietary supplementation with linseed oil.

PubMed

Li, Ran; Ibeagha-Awemu, Eveline M

2017-05-01

Recently we showed that 5% linseed oil (LSO) and 5% safflower oil (SFO) supplementation of cow's diets reduced milk fat yield by 30·38 and 32·42% respectively, accompanied by differential expression of genes and regulation by microRNAs (miRNA). This research communication addresses the hypothesis that epigenetic regulation could be involved in the observed milk fat reduction. Thus, this study investigated the gene expression pattern of major epigenetic modifying enzymes in response to dietary supplementation with LSO or SFO. Twenty-six Canadian Holstein cows in mid lactation were randomly assigned to two groups (13/group) and fed a control diet for 28 d (day -28 to -1) (control period- CP) followed by a treatment period (TP) (control diet supplemented with 5% LSO (LSO treatment) or 5% SFO (SFO treatment) of 28 d (day +1 to +28). After treatment, cows in the two groups were returned to the control diet for another 28 d (day +29 to +56) (post treatment period-PTP). Milk samples were collected on day -1 (CP), +7, +28 (TP) and +56 (PTP) for RNA isolation and measurement of the expression of thirteen epigenetic modifying genes including two DNA methytrasferases (DNMT1, DNMT3A), four histone acetylases (HAT1, KAT2A, KAT5 and CREBBP), five histone deacetylases (HDAC1, HDAC2, HDAC3, SIRT1 and SIRT2) and two histone methytransferases (EHMT2 and PRMT1) by qPCR. Linseed oil supplementation significantly repressed the expression of EHMT2, HDAC2 and HDAC3 on day +7 (P < 0·05) and KAT2A and SIRT2 on day +28 (P < 0·05) as compared with the control period (day -1) while SFO had no effect. When LSO was withdrawn, the expression of some of the genes increased slightly but did not reach control (day -1) levels at the end of the PTP. Our study demonstrated a significant role of LSO in the epigenetic regulation of fatty acid synthesis as compared to SFO. The effect of LSO may be related to its higher degree of unsaturation and might represent a different regulatory mechanism which needs further investigation.

Characterization of physiological and molecular processes associated with potato response to Zebra chip disease

USDA-ARS?s Scientific Manuscript database

Transcriptional analyses were applied to identify molecular mechanisms associated with the response of leaf and root potato tissues to ‘Ca. Liberibacter solanacearum’ (Lso) infection, causal agent of zebra chip disease (ZC). Lso infection affected several host processes including defense response-, ...

Sequence analysis of Candidatus Liberibacter solanacearum (Lso-C) isolated from carrot psyllids collected in Scandinavia

USDA-ARS?s Scientific Manuscript database

The fastidious prokaryote Candidatus Liberibacter solanacearum (Lso), transmitted by the tomato potato psyllid (Bactericera cockerelli), is associated with the Zebra Chip disease of potato. Plants infected with Liberibacter may experience significant yield losses and these plants also serve as pote...

Characterization of the Serralysin-like gene of 'Ca. Liberibacter solanacearum' associated with Potato Zebra Chip disease

USDA-ARS?s Scientific Manuscript database

The non-culturable bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) is the causative agent of zebra chip disease in potato. Computational analysis of the Lso genome revealed a serralysin-like gene based on conserved domains characteristic of genes encoding metalloprotease enzymes similar to se...

Working towards developing potato tolerance of zebra chip disease: a food science perspective

USDA-ARS?s Scientific Manuscript database

Potato zebra chip is a major threat to worldwide potato production and is caused by ‘Candidatus Liberibacter solanacearum’ (Lso), which is vectored by potato psyllids. Albeit control can be achieved by use of insecticides to limit psyllid populations and therefore Lso spread, the recent development ...

Monte Carlo calculations of PET coincidence timing: single and double-ended readout

PubMed Central

Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

2016-01-01

We present Monte Carlo computational methods for estimating the coincidence resolving time (CRT) of scintillator detector pairs in positron emission tomography (PET) and present results for Lu2SiO5 : Ce (LSO), LaBr3 : Ce, and a hypothetical ultra-fast scintillator with a 1 ns decay time. The calculations were applied to both single-ended and double-ended photodetector readout with constant-fraction triggering. They explicitly include (1) the intrinsic scintillator properties (luminosity, rise time, decay time, and index of refraction), (2) the exponentially distributed depths of interaction, (3) the optical photon transport efficiency, delay, and time dispersion, (4) the photodetector properties (fill factor, quantum efficiency, transit time jitter, and single electron response), and (5) the determination of the constant fraction trigger level that minimizes the CRT. The calculations for single-ended readout include the delayed photons from the opposite reflective surface. The calculations for double-ended readout include (1) the simple average of the two photodetector trigger times, (2) more accurate estimators of the annihilation photon entrance time using the pulse height ratio to estimate the depth of interaction and correct for annihilation photon, optical photon, and trigger delays, and (3) the statistical lower bound for interactions at the center of the crystal. For time-of-flight (TOF) PET we combine stopping power and TOF information in a figure of merit equal to the sensitivity gain relative to whole-body non-TOF PET using LSO. For LSO crystals 3 mm × 3 mm × 30 mm, a decay time of 37 ns, a total photoelectron count of 4000, and a photodetector with 0.2 ns full-width at half-maximum (fwhm) timing jitter, single-ended readout has a CRT of 0.16 ns fwhm and double-ended readout has a CRT of 0.111 ns fwhm. For LaBr3 : Ce crystals 3 mm × 3 mm × 30 mm, a rise time of 0.2 ns, a decay time of 18 ns, and a total of 7600 photoelectrons the CRT numbers are 0.14 ns and 0.072 ns fwhm, respectively. For a hypothetical ultra-fast scintillator 3 mm × 3 mm × 30 mm, a decay time of 1 ns, and a total of 4000 photoelectrons, the CRT numbers are 0.070 and 0.020 ns fwhm, respectively. Over a range of examples, values for double-ended readout are about 10% larger than the statistical lower bound. PMID:26350162

Diode-pumped continuous wave tunable and graphene Q-switched Tm:LSO lasers.

PubMed

Feng, T L; Zhao, S Z; Yang, K J; Li, G Q; Li, D C; Zhao, J; Qiao, W C; Hou, J; Yang, Y; He, J L; Zheng, L H; Wang, Q G; Xu, X D; Su, L B; Xu, J

2013-10-21

We have investigated the lasing characteristics of Tm:LSO crystal in three operation regimes: continuous wave (CW), wavelength tunable and passive Q-switching based on graphene. In CW regime, a maximum output power of 0.65 W at 2054.9 nm with a slope efficiency of 21% was achieved. With a quartz plate, a broad wavelength tunable range of 145 nm was obtained, corresponding to a FWHM of 100 nm. By using a graphene saturable absorber mirror, the passively Q-switched Tm:LSO laser produced pulses with duration of 7.8 μs at 2030.8 nm under a repetition rate of 7.6 kHz, corresponding to pulse energy of 14.0 μJ.

Variations in Zebra Chip disease expression and tuber biochemistry in response to vector density

USDA-ARS?s Scientific Manuscript database

This study examined effects of the number of ‘Candidatus Liberibacter solanacearum’ (Lso)-positive psyllids feeding on potatoes to Lso titers, zebra chip disease (ZC) symptom severity, and levels of amino acids, carbohydrates, and phenolics in tubers harvested weeks later. Red La Soda and Russet Nor...

Characterizing zebra chip symptom severity and identifying spectral signatures associated with 'Candidatus Liberibacter solanacearum' infected potato tubers

USDA-ARS?s Scientific Manuscript database

Zebra chip (ZC) is a disease of potatoes, which is associated with the bacteria ‘Candidatus Liberibacter solanacearum’ (Lso). Lso is transmitted by the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). ZC reduces yield and quality, as it results in discoloration of the vascular ...

The Military Efficacy of Individual Water Purification Filters.

DTIC Science & Technology

1990-12-01

criteria. ’t *.;as a.Lso serv ea that the KPF units grew opportunistic Pseudomonas sp . on the oroduct water side of the filters, which could have a...small pathogenic protozoan cysts such as Cryptospor-dium parvum, Giardia lamblia, and Entamoeba coli, from water over the effective use life of the...of heterotrophic bacteria such as Pseudoronas sP , Flavobacterium Sp , and other potentially harmfui organisms inside of the units. Enteric viruses are

Roles for Coincidence Detection in Coding Amplitude-Modulated Sounds

PubMed Central

Ashida, Go; Kretzberg, Jutta; Tollin, Daniel J.

2016-01-01

Many sensory neurons encode temporal information by detecting coincident arrivals of synaptic inputs. In the mammalian auditory brainstem, binaural neurons of the medial superior olive (MSO) are known to act as coincidence detectors, whereas in the lateral superior olive (LSO) roles of coincidence detection have remained unclear. LSO neurons receive excitatory and inhibitory inputs driven by ipsilateral and contralateral acoustic stimuli, respectively, and vary their output spike rates according to interaural level differences. In addition, LSO neurons are also sensitive to binaural phase differences of low-frequency tones and envelopes of amplitude-modulated (AM) sounds. Previous physiological recordings in vivo found considerable variations in monaural AM-tuning across neurons. To investigate the underlying mechanisms of the observed temporal tuning properties of LSO and their sources of variability, we used a simple coincidence counting model and examined how specific parameters of coincidence detection affect monaural and binaural AM coding. Spike rates and phase-locking of evoked excitatory and spontaneous inhibitory inputs had only minor effects on LSO output to monaural AM inputs. In contrast, the coincidence threshold of the model neuron affected both the overall spike rates and the half-peak positions of the AM-tuning curve, whereas the width of the coincidence window merely influenced the output spike rates. The duration of the refractory period affected only the low-frequency portion of the monaural AM-tuning curve. Unlike monaural AM coding, temporal factors, such as the coincidence window and the effective duration of inhibition, played a major role in determining the trough positions of simulated binaural phase-response curves. In addition, empirically-observed level-dependence of binaural phase-coding was reproduced in the framework of our minimalistic coincidence counting model. These modeling results suggest that coincidence detection of excitatory and inhibitory synaptic inputs is essential for LSO neurons to encode both monaural and binaural AM sounds. PMID:27322612

A phoswich detector design for improved spatial sampling in PET

NASA Astrophysics Data System (ADS)

Thiessen, Jonathan D.; Koschan, Merry A.; Melcher, Charles L.; Meng, Fang; Schellenberg, Graham; Goertzen, Andrew L.

2018-02-01

Block detector designs, utilizing a pixelated scintillator array coupled to a photosensor array in a light-sharing design, are commonly used for positron emission tomography (PET) imaging applications. In practice, the spatial sampling of these designs is limited by the crystal pitch, which must be large enough for individual crystals to be resolved in the detector flood image. Replacing the conventional 2D scintillator array with an array of phoswich elements, each consisting of an optically coupled side-by-side scintillator pair, may improve spatial sampling in one direction of the array without requiring resolving smaller crystal elements. To test the feasibility of this design, a 4 × 4 phoswich array was constructed, with each phoswich element consisting of two optically coupled, 3 . 17 × 1 . 58 × 10mm3 LSO crystals co-doped with cerium and calcium. The amount of calcium doping was varied to create a 'fast' LSO crystal with decay time of 32.9 ns and a 'slow' LSO crystal with decay time of 41.2 ns. Using a Hamamatsu R8900U-00-C12 position-sensitive photomultiplier tube (PS-PMT) and a CAEN V1720 250 MS/s waveform digitizer, we were able to show effective discrimination of the fast and slow LSO crystals in the phoswich array. Although a side-by-side phoswich array is feasible, reflections at the crystal boundary due to a mismatch between the refractive index of the optical adhesive (n = 1 . 5) and LSO (n = 1 . 82) caused it to behave optically as an 8 × 4 array rather than a 4 × 4 array. Direct coupling of each phoswich element to individual photodetector elements may be necessary with the current phoswich array design. Alternatively, in order to implement this phoswich design with a conventional light sharing PET block detector, a high refractive index optical adhesive is necessary to closely match the refractive index of LSO.

Prospective PET image quality gain calculation method by optimizing detector parameters.

PubMed

Theodorakis, Lampros; Loudos, George; Prassopoulos, Vasilios; Kappas, Constantine; Tsougos, Ioannis; Georgoulias, Panagiotis

2015-12-01

Lutetium-based scintillators with high-performance electronics introduced time-of-flight (TOF) reconstruction in the clinical setting. Let G' be the total signal to noise ratio gain in a reconstructed image using the TOF kernel compared with conventional reconstruction modes. G' is then the product of G1 gain arising from the reconstruction process itself and (n-1) other gain factors (G2, G3, … Gn) arising from the inherent properties of the detector. We calculated G2 and G3 gains resulting from the optimization of the coincidence and energy window width for prompts and singles, respectively. Both quantitative and image-based validated Monte Carlo models of Lu2SiO5 (LSO) TOF-permitting and Bi4Ge3O12 (BGO) TOF-nonpermitting detectors were used for the calculations. G2 and G3 values were 1.05 and 1.08 for the BGO detector and G3 was 1.07 for the LSO. A value of almost unity for G2 of the LSO detector indicated a nonsignificant optimization by altering the energy window setting. G' was found to be ∼1.4 times higher for the TOF-permitting detector after reconstruction and optimization of the coincidence and energy windows. The method described could potentially predict image noise variations by altering detector acquisition parameters. It could also further contribute toward a long-lasting debate related to cost-efficiency issues of TOF scanners versus the non-TOF ones. Some vendors re-engage nowadays to non-TOF product line designs in an effort to reduce crystal costs. Therefore, exploring the limits of image quality gain by altering the parameters of these detectors remains a topical issue.

State of the art timing in TOF-PET detectors with LuAG, GAGG and L(Y)SO scintillators of various sizes coupled to FBK-SiPMs

NASA Astrophysics Data System (ADS)

Gundacker, S.; Acerbi, F.; Auffray, E.; Ferri, A.; Gola, A.; Nemallapudi, M. V.; Paternoster, G.; Piemonte, C.; Lecoq, P.

2016-08-01

Time of flight (TOF) in positron emission tomography (PET) has experienced a revival of interest after its first introduction in the eighties. This is due to a significant progress in solid state photodetectors (SiPMs) and newly developed scintillators (LSO and its derivatives). Latest developments at Fondazione Bruno Kessler (FBK) lead to the NUV-HD SiPM with a very high photon detection efficiency of around 55%. Despite the large area of 4×4 mm2 it achieves a good single photon time resolution (SPTR) of 180±5ps FWHM. Coincidence time resolution (CTR) measurements using LSO:Ce codoped with Ca scintillators yield best values of 73±2ps FWHM for 2×2×3 mm3 and 117±3ps for 2×2×20 mm3 crystal sizes. Increasing the crystal cross-section from 2×2 mm2 to 3×3 mm2 a non negligible CTR deterioration of approximately 7ps FWHM is observed. Measurements with LSO:Ce codoped Ca and LYSO:Ce scintillators with various cross-sections (1×1 mm2 - 4×4 mm2) and lengths (3mm - 30mm) will be a basis for discussing on how the crystal geometry affects timing in TOF-PET. Special attention is given to SiPM parameters, e.g. SPTR and optical crosstalk, and their measured dependency on the crystal cross-section. Additionally, CTR measurements with LuAG:Ce, LuAG:Pr and GGAG:Ce samples are presented and the results are interpreted in terms of their scintillation properties, e.g. rise time, decay time, light yield and emission spectra.

Critical congenital heart disease--utility of routine screening for chromosomal and other extracardiac malformations.

PubMed

Baker, Kimberly; Sanchez-de-Toledo, Joan; Munoz, Ricardo; Orr, Richard; Kiray, Shareen; Shiderly, Dana; Clemens, Michele; Wearden, Peter; Morell, Victor O; Chrysostomou, Constantinos

2012-01-01

Objective.  Infants with critical congenital heart disease (CHD) can have genetic and other extracardiac malformations, which add to the short- and long-term risk of morbidity and perhaps mortality. We sought to examine our center's practice of screening for extracardiac anomalies and to determine the yield of these tests among specific cardiac diagnostic categories. Design.  Retrospective review of infants admitted to the cardiac intensive care unit with a new diagnosis of CHD. Subjects were categorized into six groups: septal defects (SD), conotruncal defects (CTD), single-ventricle physiology (SV), left-sided obstructive lesions (LSO), right-sided obstructive lesions (RSO), and "other" (anomalous pulmonary venous return, Ebstein's anomaly). Screening modalities included genetic testing (karyotype and fluorescent in situ hybridization for 22q11.2 deletion), renal ultrasound (RUS), and head ultrasound (HUS). Results.  One hundred forty-one patients were identified. The incidence of cardiac anomalies was: CTD (36%), SD (18%), SV (18%), LSO (14%), RSO (3%), and "other" (8%). Overall 14% had an abnormal karyotype, 5% had a deletion for 22q11.2, 28% had an abnormal RUS and 22% had abnormal HUS. Patients in SD and SV had the highest incidence of abnormal karyotype (36% and 17%); 22q11.2 deletion was present only in CTD and LSO groups (9% and 7%, respectively); abnormal RUS and HUS were seen relatively uniformly in all categories. Premature infants had significantly higher incidence of renal 43% vs. 24%, and intracranial abnormalities 46% vs. 16%. Conclusion.  Infants with critical CHD and particularly premature infants have high incidence of genetic and other extracardiac anomalies. Universal screening for these abnormalities with ultrasonographic and genetic testing maybe warranted because early detection could impact short and long-term outcomes. © 2011 Wiley Periodicals, Inc.

Monte Carlo calculations of PET coincidence timing: single and double-ended readout

NASA Astrophysics Data System (ADS)

Derenzo, Stephen E.; Choong, Woon-Seng; Moses, William W.

2015-09-01

We present Monte Carlo computational methods for estimating the coincidence resolving time (CRT) of scintillator detector pairs in positron emission tomography (PET) and present results for Lu2SiO5 : Ce (LSO), LaBr3 : Ce, and a hypothetical ultra-fast scintillator with a 1 ns decay time. The calculations were applied to both single-ended and double-ended photodetector readout with constant-fraction triggering. They explicitly include (1) the intrinsic scintillator properties (luminosity, rise time, decay time, and index of refraction), (2) the exponentially distributed depths of interaction, (3) the optical photon transport efficiency, delay, and time dispersion, (4) the photodetector properties (fill factor, quantum efficiency, transit time jitter, and single electron response), and (5) the determination of the constant fraction trigger level that minimizes the CRT. The calculations for single-ended readout include the delayed photons from the opposite reflective surface. The calculations for double-ended readout include (1) the simple average of the two photodetector trigger times, (2) more accurate estimators of the annihilation photon entrance time using the pulse height ratio to estimate the depth of interaction and correct for annihilation photon, optical photon, and trigger delays, and (3) the statistical lower bound for interactions at the center of the crystal. For time-of-flight (TOF) PET we combine stopping power and TOF information in a figure of merit equal to the sensitivity gain relative to whole-body non-TOF PET using LSO. For LSO crystals 3 mm  ×  3 mm  ×  30 mm, a decay time of 37 ns, a total photoelectron count of 4000, and a photodetector with 0.2 ns full-width at half-maximum (fwhm) timing jitter, single-ended readout has a CRT of 0.16 ns fwhm and double-ended readout has a CRT of 0.111 ns fwhm. For LaBr3 : Ce crystals 3 mm  ×  3 mm  ×  30 mm, a rise time of 0.2 ns, a decay time of 18 ns, and a total of 7600 photoelectrons the CRT numbers are 0.14 ns and 0.072 ns fwhm, respectively. For a hypothetical ultra-fast scintillator 3 mm  ×  3 mm  ×  30 mm, a decay time of 1 ns, and a total of 4000 photoelectrons, the CRT numbers are 0.070 and 0.020 ns fwhm, respectively. Over a range of examples, values for double-ended readout are about 10% larger than the statistical lower bound.

Monte Carlo calculations of PET coincidence timing: single and double-ended readout.

PubMed

Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

2015-09-21

We present Monte Carlo computational methods for estimating the coincidence resolving time (CRT) of scintillator detector pairs in positron emission tomography (PET) and present results for Lu2SiO5 : Ce (LSO), LaBr3 : Ce, and a hypothetical ultra-fast scintillator with a 1 ns decay time. The calculations were applied to both single-ended and double-ended photodetector readout with constant-fraction triggering. They explicitly include (1) the intrinsic scintillator properties (luminosity, rise time, decay time, and index of refraction), (2) the exponentially distributed depths of interaction, (3) the optical photon transport efficiency, delay, and time dispersion, (4) the photodetector properties (fill factor, quantum efficiency, transit time jitter, and single electron response), and (5) the determination of the constant fraction trigger level that minimizes the CRT. The calculations for single-ended readout include the delayed photons from the opposite reflective surface. The calculations for double-ended readout include (1) the simple average of the two photodetector trigger times, (2) more accurate estimators of the annihilation photon entrance time using the pulse height ratio to estimate the depth of interaction and correct for annihilation photon, optical photon, and trigger delays, and (3) the statistical lower bound for interactions at the center of the crystal. For time-of-flight (TOF) PET we combine stopping power and TOF information in a figure of merit equal to the sensitivity gain relative to whole-body non-TOF PET using LSO. For LSO crystals 3 mm  ×  3 mm  ×  30 mm, a decay time of 37 ns, a total photoelectron count of 4000, and a photodetector with 0.2 ns full-width at half-maximum (fwhm) timing jitter, single-ended readout has a CRT of 0.16 ns fwhm and double-ended readout has a CRT of 0.111 ns fwhm. For LaBr3 : Ce crystals 3 mm  ×  3 mm  ×  30 mm, a rise time of 0.2 ns, a decay time of 18 ns, and a total of 7600 photoelectrons the CRT numbers are 0.14 ns and 0.072 ns fwhm, respectively. For a hypothetical ultra-fast scintillator 3 mm  ×  3 mm  ×  30 mm, a decay time of 1 ns, and a total of 4000 photoelectrons, the CRT numbers are 0.070 and 0.020 ns fwhm, respectively. Over a range of examples, values for double-ended readout are about 10% larger than the statistical lower bound.

Local Structure Theory for Cellular Automata.

NASA Astrophysics Data System (ADS)

Gutowitz, Howard Andrew

The local structure theory (LST) is a generalization of the mean field theory for cellular automata (CA). The mean field theory makes the assumption that iterative application of the rule does not introduce correlations between the states of cells in different positions. This assumption allows the derivation of a simple formula for the limit density of each possible state of a cell. The most striking feature of CA is that they may well generate correlations between the states of cells as they evolve. The LST takes the generation of correlation explicitly into account. It thus has the potential to describe statistical characteristics in detail. The basic assumption of the LST is that though correlation may be generated by CA evolution, this correlation decays with distance. This assumption allows the derivation of formulas for the estimation of the probability of large blocks of states in terms of smaller blocks of states. Given the probabilities of blocks of size n, probabilities may be assigned to blocks of arbitrary size such that these probability assignments satisfy the Kolmogorov consistency conditions and hence may be used to define a measure on the set of all possible (infinite) configurations. Measures defined in this way are called finite (or n-) block measures. A function called the scramble operator of order n maps a measure to an approximating n-block measure. The action of a CA on configurations induces an action on measures on the set of all configurations. The scramble operator is combined with the CA map on measure to form the local structure operator (LSO). The LSO of order n maps the set of n-block measures into itself. It is hypothesised that the LSO applied to n-block measures approximates the rule itself on general measures, and does so increasingly well as n increases. The fundamental advantage of the LSO is that its action is explicitly computable from a finite system of rational recursion equations. Empirical study of a number of CA rules demonstrates the potential of the LST to describe the statistical features of CA. The behavior of some simple rules is derived analytically. Other rules have more complex, chaotic behavior. Even for these rules, the LST yields an accurate portrait of both small and large time statistics.

Benefits of Continuing Professional Development (CPD) Programmes in Music for KS2 (Primary) Teachers through the Example of the London Symphony Orchestra (LSO) on Track Programme

ERIC Educational Resources Information Center

Varvarigou, Maria; Creech, Andrea; Hallam, Susan

2012-01-01

Between September 2008 and August 2010 24 KS2 classroom teachers were involved in a two-year programme of continuing professional development (CPD), delivered by the LSO in partnership with Local Authority Music Services. The teachers indicated that they embarked on the CPD programme looking forward to opportunities to share good practice, gain…

Transcriptome adaptation of the bovine mammary gland to diets rich in unsaturated fatty acids shows greater impact of linseed oil over safflower oil on gene expression and metabolic pathways.

PubMed

Ibeagha-Awemu, Eveline M; Li, Ran; Ammah, Adolf A; Dudemaine, Pier-Luc; Bissonnette, Nathalie; Benchaar, Chaouki; Zhao, Xin

2016-02-09

Nutritional strategies can decrease saturated fatty acids (SFAs) and increase health beneficial fatty acids (FAs) in bovine milk. The pathways/genes involved in these processes are not properly defined. Next-generation RNA-sequencing was used to investigate the bovine mammary gland transcriptome following supplemental feeding with 5% linseed oil (LSO) or 5% safflower oil (SFO). Holstein cows in mid-lactation were fed a control diet for 28 days (control period) followed by supplementation with 5% LSO (12 cows) or 5% SFO (12 cows) for 28 days (treatment period). Milk and mammary gland biopsies were sampled on days-14 (control period), +7 and +28 (treatment period). Milk was used to measure fat(FP)/protein(PP) percentages and individual FAs while RNA was subjected to sequencing. Milk FP was decreased by 30.38% (LSO) or 32.42% (SFO) while PP was unaffected (LSO) or increased (SFO). Several beneficial FAs were increased by LSO (C18:1n11t, CLA:10t12c, CLA:9c11t, C20:3n3, C20:5n3, C22:5n3) and SFO (C18:1n11t, CLA:10t12c, C20:1c11, C20:2, C20:3n3) while several SFAs (C4:0, C6:0, C8:0, C14:0, C16:0, C17:0, C24:0) were decreased by both treatments (P < 0.05). 1006 (460 up- and 546 down-regulated) and 199 (127 up- and 72 down-regulated) genes were significantly differentially regulated (DE) by LSO and SFO, respectively. Top regulated genes (≥ 2 fold change) by both treatments (FBP2, UCP2, TIEG2, ANGPTL4, ALDH1L2) are potential candidate genes for milk fat traits. Involvement of SCP2, PDK4, NQO1, F2RL1, DBI, CPT1A, CNTFR, CALB1, ACADVL, SPTLC3, PIK3CG, PIGZ, ADORA2B, TRIB3, HPGD, IGFBP2 and TXN in FA/lipid metabolism in dairy cows is being reported for the first time. Functional analysis indicated similar and different top enriched functions for DE genes. DE genes were predicted to significantly decrease synthesis of FA/lipid by both treatments and FA metabolism by LSO. Top canonical pathways associated with DE genes of both treatments might be involved in lipid/cholesterol metabolism. This study shows that rich α-linolenic acid LSO has a greater impact on mammary gland transcriptome by affecting more genes, pathways and processes as compared to SFO, rich in linoleic acid. Our study suggest that decrease in milk SFAs was due to down-regulation of genes in the FA/lipid synthesis and lipid metabolism pathways while increase in PUFAs was due to increased availability of ruminal biohydrogenation metabolites that were up taken and incorporated into milk or used as substrate for the synthesis of PUFAs.

Performance of the Tachyon Time-of-Flight PET Camera

NASA Astrophysics Data System (ADS)

Peng, Q.; Choong, W.-S.; Vu, C.; Huber, J. S.; Janecek, M.; Wilson, D.; Huesman, R. H.; Qi, Jinyi; Zhou, Jian; Moses, W. W.

2015-02-01

We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 ×25 mm2 side of 6.15 ×6.15 ×25 mm3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- 20 ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.

Performance of the Tachyon Time-of-Flight PET Camera.

PubMed

Peng, Q; Choong, W-S; Vu, C; Huber, J S; Janecek, M; Wilson, D; Huesman, R H; Qi, Jinyi; Zhou, Jian; Moses, W W

2015-02-01

We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 × 25 mm 2 side of 6.15 × 6.15 × 25 mm 3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.

Changes in sleep characteristics and airway obstruction in OSAHS patients with multi-level obstruction following simple UPPP, UPPP-GA, or UPPP-TBA: a prospective, single-center, parallel group study.

PubMed

Chen, Shicai; Shi, Song; Xia, Yanghui; Liu, Fei; Chen, Donghui; Zhu, Minhui; Li, Meng; Zheng, Hongliang

2014-01-01

To investigate changes in S3 sleep and the apnea hypopnea index (AHI), SpO2 desaturation and CT90, and to determine changes in the degree of airway collapse and in the cross-sectional area of the retropalatal and lingual region in obstructive sleep apnea hypopnea syndrome patients. All subjects underwent overnight polysomnography and were evaluated using Müller's test and magnetic resonance imaging at baseline, 3, and 12 months following surgery. The mean S3 scores in patients receiving uvulopalatopharyngoplasty combined with genioglossus advancement (UPPP-GA) or UPPP combined with tongue base advancement using the Repose™ system (UPPP-TBA) noticeably increased. Marked improvement was seen in the mean AHI, LSO2, and CT90 scores 3 and 12 months following surgery compared to baseline. Airway collapsed by 25-50% in the greatest proportion undergoing surgery at the tongue base. UPPP-GA and UPPP-TBA more effectively improve S3 sleep, and mean AHI, LSO2, and CT90 scores. In addition, they effectively alleviate airway obstruction by improving the cross-sectional area of these regions. © 2014 S. Karger AG, Basel.

Performance of the Tachyon Time-of-Flight PET Camera

PubMed Central

Peng, Q.; Choong, W.-S.; Vu, C.; Huber, J. S.; Janecek, M.; Wilson, D.; Huesman, R. H.; Qi, Jinyi; Zhou, Jian; Moses, W. W.

2015-01-01

We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon’s detector module is optimized for timing by coupling the 6.15 × 25 mm2 side of 6.15 × 6.15 × 25 mm3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according to the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/− ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. The results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3. PMID:26594057

Performance of the Tachyon Time-of-Flight PET Camera

DOE PAGES

Peng, Q.; Choong, W. -S.; Vu, C.; ...

2015-01-23

We have constructed and characterized a time-of-flight Positron Emission Tomography (TOF PET) camera called the Tachyon. The Tachyon is a single-ring Lutetium Oxyorthosilicate (LSO) based camera designed to obtain significantly better timing resolution than the ~ 550 ps found in present commercial TOF cameras, in order to quantify the benefit of improved TOF resolution for clinically relevant tasks. The Tachyon's detector module is optimized for timing by coupling the 6.15 ×25 mm 2 side of 6.15 ×6.15 ×25 mm 3 LSO scintillator crystals onto a 1-inch diameter Hamamatsu R-9800 PMT with a super-bialkali photocathode. We characterized the camera according tomore » the NEMA NU 2-2012 standard, measuring the energy resolution, timing resolution, spatial resolution, noise equivalent count rates and sensitivity. The Tachyon achieved a coincidence timing resolution of 314 ps +/- 20 ps FWHM over all crystal-crystal combinations. Experiments were performed with the NEMA body phantom to assess the imaging performance improvement over non-TOF PET. We find that the results show that at a matched contrast, incorporating 314 ps TOF reduces the standard deviation of the contrast by a factor of about 2.3.« less

See-through ophthalmoscope for retinal imaging

NASA Astrophysics Data System (ADS)

Carpentras, Dino; Moser, Christophe

2017-05-01

With the miniaturization of scanning mirrors and the emergence of wearable health monitoring, an intriguing step is to investigate the potential of a laser scanning ophthalmoscope (LSO) for retinal imaging with wearable glasses. In addition to providing morphological information of the retina, such as vasculature, LSO images could also be used to provide information on general health conditions. A compact eyeglass with LSO capability would give access, on demand, to retinal parameters without disturbing the subject's activity. One of the main challenges in this field is the creation of a device that does not interrupt the user's field of view. We report, to our knowledge, the first see-through ophthalmoscope. The system is analyzed with three-dimensional simulations and tested in a proof-of-concept setup with the same key parameters of a wearable device. Finally, image quality is analyzed by acquiring images of an ex-vivo human eye sample.

Voice Technology Design Guides for Navy Training Systems.

DTIC Science & Technology

1983-03-01

34 LSO acknowledges (AUTOIMANUAL/ pilot meatball Coupled as acquisition. appropriate) "Paddles Contact" LSO assuming control from CCA. (continued) 68... meatball to avoid ball to avoid settling slope if not corrected. settling below glide- below glideslope. slope. "Don’t climb"- If not corrected air...Check sink rate and Check sink rate and meat- "Don’t go high." craft will climb above meatball to avoid ball to avoid climbing optimum glideslope

Charlie, Development of a Light-Weight, Virtual Reality Trainer for the LSO Community: Time to Make the Leap Toward Immersive VR

DTIC Science & Technology

2015-09-01

Training System ARB Aircraft Recovery Bulletins AR Augmented Reality CAG Carrier Air Group CATCC Carrier Air Traffic Control Center COTS...in integration of an optical lens systems into the aircraft carrier. The current generation of optical lens systems integrated into aircraft ...The use of MOVLAS on an aircraft carrier represents a direct communication link between the LSO and pilot. As a backup landing aid system to

Flexible composite radiation detector

DOEpatents

Cooke, D Wayne [Santa Fe, NM; Bennett, Bryan L [Los Alamos, NM; Muenchausen, Ross E [Los Alamos, NM; Wrobleski, Debra A [Los Alamos, NM; Orler, Edward B [Los Alamos, NM

2006-12-05

A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.

Simultaneous MRI and PET imaging of a rat brain

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan K.; Sendhil Velan, S.; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Zorn, Carl; Marano, Gary D.

2006-12-01

Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI will allow the correlation of form with function. Our group is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode. Each MRI-PET detector module consists of an array of LSO detector elements coupled through a long fibre optic light guide to a single Hamamatsu flat panel position-sensitive photomultiplier tube (PSPMT). The use of light guides allows the PSPMTs to be positioned outside the bore of a 3T MRI scanner where the magnetic field is relatively small. To test the device, simultaneous MRI and PET images of the brain of a male Sprague Dawley rat injected with FDG were successfully obtained. The images revealed no noticeable artefacts in either image set. Future work includes the construction of a full ring PET scanner, improved light guides and construction of a specialized MRI coil to permit higher quality MRI imaging.

Ephrin-B2 Reverse Signaling Is Required for Topography but Not Pattern Formation of Lateral Superior Olivary Inputs to the Inferior Colliculus

PubMed Central

Wallace, Matthew M.; Kavianpour, Sarah M.; Gabriele, Mark L.

2014-01-01

Graded and modular expressions of Eph-ephrins are known to provide positional information for the formation of topographic maps and patterning in the developing nervous system. Previously we have shown that ephrin-B2 is expressed in a continuous gradient across the tonotopic axis of the central nucleus of the inferior colliculus (CNIC), whereas patterns are discontinuous and modular in the lateral cortex of the IC (LCIC). The present study explores the involvement of ephrin-B2 signaling in the development of projections to the CNIC and LCIC arising from the lateral superior olivary nuclei (LSO) prior to hearing onset. Anterograde and retrograde fluorescent tracing methods in neonatal fixed tissue preparations were used to compare topographic mapping and the establishment of LSO layers/modules in wild-type and ephrin-B2lacZ/+ mice (severely compromised reverse signaling). At birth, pioneer LSO axons occupy the ipsilateral IC in both groups but are delayed contralaterally in ephrin-B2lacZ/+ mutants. By the onset of hearing, both wild-type and mutant projections form discernible layers bilaterally in the CNIC and modular arrangements within the ipsilateral LCIC. In contrast, ephrin-B2lacZ/+ mice lack a reliable topography in LSO-IC projections, suggesting that fully functional ephrin-B2 reverse signaling is required for normal projection mapping. Taken together, these ephrin-B2 findings paired with known coexpression of EphA4 suggest the importance of these signaling proteins in establishing functional auditory circuits prior to experience. PMID:23042409

Ephrin-B2 reverse signaling is required for topography but not pattern formation of lateral superior olivary inputs to the inferior colliculus.

PubMed

Wallace, Matthew M; Kavianpour, Sarah M; Gabriele, Mark L

2013-05-01

Graded and modular expressions of Eph-ephrins are known to provide positional information for the formation of topographic maps and patterning in the developing nervous system. Previously we have shown that ephrin-B2 is expressed in a continuous gradient across the tonotopic axis of the central nucleus of the inferior colliculus (CNIC), whereas patterns are discontinuous and modular in the lateral cortex of the IC (LCIC). The present study explores the involvement of ephrin-B2 signaling in the development of projections to the CNIC and LCIC arising from the lateral superior olivary nuclei (LSO) prior to hearing onset. Anterograde and retrograde fluorescent tracing methods in neonatal fixed tissue preparations were used to compare topographic mapping and the establishment of LSO layers/modules in wild-type and ephrin-B2(lacZ/+) mice (severely compromised reverse signaling). At birth, pioneer LSO axons occupy the ipsilateral IC in both groups but are delayed contralaterally in ephrin-B2(lacZ/+) mutants. By the onset of hearing, both wild-type and mutant projections form discernible layers bilaterally in the CNIC and modular arrangements within the ipsilateral LCIC. In contrast, ephrin-B2(lacZ/+) mice lack a reliable topography in LSO-IC projections, suggesting that fully functional ephrin-B2 reverse signaling is required for normal projection mapping. Taken together, these ephrin-B2 findings paired with known coexpression of EphA4 suggest the importance of these signaling proteins in establishing functional auditory circuits prior to experience. Copyright © 2012 Wiley Periodicals, Inc.

Monitoring Energy Calibration Drift Using the Scintillator Background Radiation

NASA Astrophysics Data System (ADS)

Conti, Maurizio; Eriksson, Lars; Hayden, Charles

2011-06-01

Scintillating materials commonly used in nuclear medicine can contain traces of isotopes that naturally emit gamma or beta radiation. Examples of these are 138La contained in LaBr3 and other Lanthanum based scintillators, and 176Lu contained in LSO, LYSO, LuYAP and other Lutetium based scintillators. In particular,176Lu decays into 176Hf and emits a beta particle with maximum energy 589 keV, and a cascade of gamma rays of energies 307 keV, 202 keV and 88 keV. We propose to use the background radiation for monitoring of detector calibration drift and for self-calibration of detectors in complex detector systems. A calibration drift due to random or systematic changes in photomultiplier tube (PMT) gain was studied in a Siemens PET scanner, based on LSO blocks. Both a conventional radioactive source (68Ge, 511 keV photons from electron-positron annihilation) and the LSO background radiation were used for calibration. The difference in the calibration peak shift at 511 keV estimated with the two methods was less than 10%.

NEMA NU 2-2007 performance measurements of the Siemens Inveon™ preclinical small animal PET system

PubMed Central

Kemp, Brad J; Hruska, Carrie B; McFarland, Aaron R; Lenox, Mark W; Lowe, Val J

2010-01-01

National Electrical Manufacturers Association (NEMA) NU 2-2007 performance measurements were conducted on the Inveon™ preclinical small animal PET system developed by Siemens Medical Solutions. The scanner uses 1.51 × 1.51 × 10 mm LSO crystals grouped in 20 × 20 blocks; a tapered light guide couples the LSO crystals of a block to a position-sensitive photomultiplier tube. There are 80 rings with 320 crystals per ring and the ring diameter is 161 mm. The transaxial and axial fields of view (FOVs) are 100 and 127 mm, respectively. The scanner can be docked to a CT scanner; the performance characteristics of the CT component are not included herein. Performance measurements of spatial resolution, sensitivity, scatter fraction and count rate performance were obtained for different energy windows and coincidence timing window widths. For brevity, the results described here are for an energy window of 350–650 keV and a coincidence timing window of 3.43 ns. The spatial resolution at the center of the transaxial and axial FOVs was 1.56, 1.62 and 2.12 mm in the tangential, radial and axial directions, respectively, and the system sensitivity was 36.2 cps kBq−1 for a line source (7.2% for a point source). For mouse- and rat-sized phantoms, the scatter fraction was 5.7% and 14.6%, respectively. The peak noise equivalent count rate with a noisy randoms estimate was 1475 kcps at 130 MBq for the mouse-sized phantom and 583 kcps at 74 MBq for the rat-sized phantom. The performance measurements indicate that the Inveon™ PET scanner is a high-resolution tomograph with excellent sensitivity that is capable of imaging at a high count rate. PMID:19321924

NEMA NU 2-2007 performance measurements of the Siemens Inveon™ preclinical small animal PET system

NASA Astrophysics Data System (ADS)

Kemp, Brad J.; Hruska, Carrie B.; McFarland, Aaron R.; Lenox, Mark W.; Lowe, Val J.

2009-04-01

National Electrical Manufacturers Association (NEMA) NU 2-2007 performance measurements were conducted on the Inveon™ preclinical small animal PET system developed by Siemens Medical Solutions. The scanner uses 1.51 × 1.51 × 10 mm LSO crystals grouped in 20 × 20 blocks; a tapered light guide couples the LSO crystals of a block to a position-sensitive photomultiplier tube. There are 80 rings with 320 crystals per ring and the ring diameter is 161 mm. The transaxial and axial fields of view (FOVs) are 100 and 127 mm, respectively. The scanner can be docked to a CT scanner; the performance characteristics of the CT component are not included herein. Performance measurements of spatial resolution, sensitivity, scatter fraction and count rate performance were obtained for different energy windows and coincidence timing window widths. For brevity, the results described here are for an energy window of 350-650 keV and a coincidence timing window of 3.43 ns. The spatial resolution at the center of the transaxial and axial FOVs was 1.56, 1.62 and 2.12 mm in the tangential, radial and axial directions, respectively, and the system sensitivity was 36.2 cps kBq-1 for a line source (7.2% for a point source). For mouse- and rat-sized phantoms, the scatter fraction was 5.7% and 14.6%, respectively. The peak noise equivalent count rate with a noisy randoms estimate was 1475 kcps at 130 MBq for the mouse-sized phantom and 583 kcps at 74 MBq for the rat-sized phantom. The performance measurements indicate that the Inveon™ PET scanner is a high-resolution tomograph with excellent sensitivity that is capable of imaging at a high count rate.

Studying the energy dependence of intrinsic conversion efficiency of single crystal scintillators under X-ray excitation

NASA Astrophysics Data System (ADS)

Kalyvas, N.; Valais, I.; David, S.; Michail, Ch.; Fountos, G.; Liaparinos, P.; Kandarakis, I.

2014-05-01

Single crystal scintilators are used in various radiation detectors applications. The efficiency of the crystal can be determined by the Detector Optical Gain (DOG) defined as the ratio of the emitted optical photon flux over the incident radiation photons flux. A parameter affecting DOG is the intrinsic conversion efficiency ( n C ) giving the percentage of the X-ray photon power converted to optical photon power. n C is considered a constant value for X-ray energies in the order of keV although a non-proportional behavior has been reported. In this work an analytical model, has been utilized to single crystals scintillators GSO:Ce, LSO:Ce and LYSO:Ce to examine whether the intrinsic conversion efficiency shows non proportional behavior under X-ray excitation. DOG was theoretically calculated as a function of the incident X-ray spectrum, the X-ray absorption efficiency, the energy of the produced optical photons and the light transmission efficiency. The theoretical DOG values were compared with experimental data obtained by irradiating the crystals with X-rays at tube voltages from 50 to 140 kV and by measuring the light energy flux emitted from the irradiated screen. An initial value for n C (calculated from literature data) was assumed for the X-ray tube voltage of 50 kV. For higher X-ray tube voltages the optical photon propagation phenomena was assumed constant and any deviations between experimental and theoretical data were associated with changes in the intrinsic conversion efficiency. The experimental errors were below 7% for each experimental setup. The behavior of n C values for LSO:Ce and LYSO:Ce were found very similar, i.e., ranging with values from 0.089 at 50 kV to 0.015 at 140 kV, while for GSO:Ce, n C demonstrated a peak at 80 kV.

Imaging properties of pixellated scintillators with deep pixels

PubMed Central

Barber, H. Bradford; Fastje, David; Lemieux, Daniel; Grim, Gary P.; Furenlid, Lars R.; Miller, Brian W.; Parkhurst, Philip; Nagarkar, Vivek V.

2015-01-01

We have investigated the light-transport properties of scintillator arrays with long, thin pixels (deep pixels) for use in high-energy gamma-ray imaging. We compared 10×10 pixel arrays of YSO:Ce, LYSO:Ce and BGO (1mm × 1mm × 20 mm pixels) made by Proteus, Inc. with similar 10×10 arrays of LSO:Ce and BGO (1mm × 1mm × 15mm pixels) loaned to us by Saint-Gobain. The imaging and spectroscopic behaviors of these scintillator arrays are strongly affected by the choice of a reflector used as an inter-pixel spacer (3M ESR in the case of the Proteus arrays and white, diffuse-reflector for the Saint-Gobain arrays). We have constructed a 3700-pixel LYSO:Ce Prototype NIF Gamma-Ray Imager for use in diagnosing target compression in inertial confinement fusion. This system was tested at the OMEGA Laser and exhibited significant optical, inter-pixel cross-talk that was traced to the use of a single-layer of ESR film as an inter-pixel spacer. We show how the optical cross-talk can be mapped, and discuss correction procedures. We demonstrate a 10×10 YSO:Ce array as part of an iQID (formerly BazookaSPECT) imager and discuss issues related to the internal activity of 176Lu in LSO:Ce and LYSO:Ce detectors. PMID:26236070

Imaging properties of pixellated scintillators with deep pixels

NASA Astrophysics Data System (ADS)

Barber, H. Bradford; Fastje, David; Lemieux, Daniel; Grim, Gary P.; Furenlid, Lars R.; Miller, Brian W.; Parkhurst, Philip; Nagarkar, Vivek V.

2014-09-01

We have investigated the light-transport properties of scintillator arrays with long, thin pixels (deep pixels) for use in high-energy gamma-ray imaging. We compared 10x10 pixel arrays of YSO:Ce, LYSO:Ce and BGO (1mm x 1mm x 20 mm pixels) made by Proteus, Inc. with similar 10x10 arrays of LSO:Ce and BGO (1mm x 1mm x 15mm pixels) loaned to us by Saint-Gobain. The imaging and spectroscopic behaviors of these scintillator arrays are strongly affected by the choice of a reflector used as an inter-pixel spacer (3M ESR in the case of the Proteus arrays and white, diffuse-reflector for the Saint-Gobain arrays). We have constructed a 3700-pixel LYSO:Ce Prototype NIF Gamma-Ray Imager for use in diagnosing target compression in inertial confinement fusion. This system was tested at the OMEGA Laser and exhibited significant optical, inter-pixel cross-talk that was traced to the use of a single-layer of ESR film as an inter-pixel spacer. We show how the optical cross-talk can be mapped, and discuss correction procedures. We demonstrate a 10x10 YSO:Ce array as part of an iQID (formerly BazookaSPECT) imager and discuss issues related to the internal activity of 176Lu in LSO:Ce and LYSO:Ce detectors.

Phenology of the Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), and "Candidatus Liberibacter solanacearum" in Commercial Potato Fields in Idaho.

PubMed

Wenninger, Erik J; Carroll, Amy; Dahan, Jennifer; Karasev, Alexander V; Thornton, Michael; Miller, Jeff; Nolte, Philip; Olsen, Nora; Price, William

2017-12-08

Zebra chip disease (ZC) is an emerging disease of potato in which tubers are produced with striped necrotic patterns that make them unmarketable. ZC is associated with the bacterium "Candidatus Liberibacter solanacearum" (Lso), which is transmitted by the potato psyllid, Bactericera cockerelli (Šulc; Hemiptera: Triozidae). First found in Idaho during 2011, ZC now contributes to increased production costs each season via additional insecticide sprays. To clarify the extent and severity of the threat of ZC in Idaho, we sampled potato psyllids in commercial potato fields across the state over four growing seasons (2012-2015). All life stages of psyllids were sampled using a combination of methods (yellow sticky traps, vacuum samples, and leaf samples), and adult psyllids were tested for the presence of Lso by Polymerase Chain Reaction (PCR). Abundance of potato psyllids initially increased gradually over each growing season, then exhibited a sharp late-season rise and a sharp decline as most fields were being harvested. Abundance of psyllids was higher at warmer, lower elevation sites, but infestation onset did not differ between growing regions. Fewer psyllids were collected in vacuum samples than in sticky trap samples. Nymphs and eggs were found only late season and during years with high abundance of adults. Overall incidence of Lso was similar among all years but one. The results presented here clarify our understanding of the seasonal phenology of potato psyllids and Lso in Idaho potato fields and will aid in developing integrated management strategies against this important pest of potato. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Scintillation properties of selected oxide monocrystals activated with Ce and Pr

NASA Astrophysics Data System (ADS)

Wojtowicz, Andrzej J.; Drozdowski, Winicjusz; Wisniewski, Dariusz; Lefaucheur, Jean-Luc; Galazka, Zbigniew; Gou, Zhenhui; Lukasiewicz, Tadeusz; Kisielewski, Jaroslaw

2006-01-01

In the last 10-15 years there has been a significant effort toward development of new, more efficient and faster materials for detection of ionizing radiation. A growing demand for better scintillator crystals for detection of 511 keV gamma particles has been due mostly to recent advances in modern imaging systems employing positron emitting radionuclides for medical diagnostics in neurology, oncology and cardiology. While older imaging systems were almost exclusively based on BGO and NaI:Tl crystals the new systems, e.g., ECAT Accel, developed by Siemens/CTI, are based on recently discovered and developed LSO (Lu 2SiO 5:Ce, Ce-activated lutetium oxyorthosilicate) crystals. Interestingly, despite very good properties of LSO, there still is a strong drive toward development of new scintillator crystals that would show even better performance and characteristics. In this presentation we shall review spectroscopic and scintillator characterization of new complex oxide crystals, namely LSO, LYSO, YAG, LuAP (LuAlO 3, lutetium aluminate perovskite) and LuYAP activated with Ce and Pr. The LSO:Ce crystals have been grown by CTI Inc (USA), LYSO:Ce, LuAP:Ce and LuYAP:Ce crystals have been grown by Photonic Materials Ltd., Scotland (PML is the only company providing large LuAP:Ce crystals on a commercial scale), while YAG:Pr and LuAP:Pr crystals have been grown by Institute of Electronic Materials Technology (Poland). All these crystals have been characterized at Institute of Physics, N. Copernicus University (Poland). We will review and compare results of measurements of radioluminescence, VUV spectroscopy, scintillation light yields, scintillation time profiles and low temperature thermoluminescence performed on these crystals. We will demonstrate that all experiments clearly indicate that there is a significant room for improvement of LuAP, LuYAP and YAG. While both Ce-activated LSO and LYSO perform very well, we also note that LuYAP:Ce, LuAP:Ce and YAG:Pr offer some advantages and, after a likely improvement of some parameters, may also present a viable and desired alternative in applications that require high counting rates or better time resolution. Unfortunately, LuAP:Pr, although the fastest among all the materials studied, may be seriously limited in its achievable light yield by inherent physical processes that are responsible for nonradiative quenching of scintillation light in this material.

CW and passively Q-switched laser performance of Nd:Lu2SiO5 crystal

NASA Astrophysics Data System (ADS)

Xu, Xiaodong; Di, Juqing; Zhang, Jian; Tang, Dingyuan; Xu, Jun

2016-01-01

We demonstrated an efficient and controllable dual-wavelength continuous-wave (CW) laser of Nd:Lu2SiO5 (Nd:LSO) crystal. The maximum output power was 3.02 W at wavelength of 1075 nm and 1079 nm, and with increasing of absorbed pump power, the ratio of 1079 nm laser rose. The slope efficiency of 65.6% and optical-to-optical conversion efficiency of 63.3% were obtained. The passively Q-switched laser properties of Nd:LSO were investigated for the first time. The shortest pulse, maximum pulse energy and peak power were 11.58 ns, 29.05 μJ and 2.34 kW, respectively.

MicroPET II: design, development and initial performance of an improved microPET scanner for small-animal imaging

NASA Astrophysics Data System (ADS)

Tai, Yuan-Chuan; Chatziioannou, Arion F.; Yang, Yongfeng; Silverman, Robert W.; Meadors, Ken; Siegel, Stefan; Newport, Danny F.; Stickel, Jennifer R.; Cherry, Simon R.

2003-06-01

MicroPET II is a second-generation animal PET scanner designed for high-resolution imaging of small laboratory rodents. The system consists of 90 scintillation detector modules arranged in three contiguous axial rings with a ring diameter of 16.0 cm and an axial length of 4.9 cm. Each detector module consists of a 14 × 14 array of lutetium oxyorthosilicate (LSO) crystals coupled to a multi-channel photomultiplier tube (MC-PMT) through a coherent optical fibre bundle. Each LSO crystal element measures 0.975 mm × 0.975 mm in cross section by 12.5 mm in length. A barium sulphate reflector material was used between LSO elements leading to a detector pitch of 1.15 mm in both axial and transverse directions. Fused optical fibre bundles were made from 90 µm diameter glass fibres with a numerical aperture of 0.56. Interstitial extramural absorber was added between the fibres to reduce optical cross talk. A charge-division readout circuit was implemented on printed circuit boards to decode the 196 crystals in each array from the outputs of the 64 anode signals of the MC-PMT. Electronics from Concorde Microsystems Inc. (Knoxville, TN) were used for signal amplification, digitization, event qualification, coincidence processing and data capture. Coincidence data were passed to a host PC that recorded events in list mode. Following acquisition, data were sorted into sinograms and reconstructed using Fourier rebinning and filtered backprojection algorithms. Basic evaluation of the system has been completed. The absolute sensitivity of the microPET II scanner was 2.26% at the centre of the field of view (CFOV) for an energy window of 250-750 keV and a timing window of 10 ns. The intrinsic spatial resolution of the detectors in the system averaged 1.21 mm full width at half maximum (FWHM) when measured with a 22Na point source 0.5 mm in diameter. Reconstructed image resolution ranged from 0.83 mm FWHM at the CFOV to 1.47 mm FWHM in the radial direction, 1.17 mm FWHM in the tangential direction and 1.42 mm FWHM in the axial direction at 1 cm offset from the CFOV. These values represent highly significant improvements over our earlier microPET scanner (approximately fourfold sensitivity increase and 25-35% improvement in linear spatial resolution under equivalent operating conditions) and are expected to be further improved when the system is fully optimized. This work was originally conducted at UCLA, Crump Institute for Molecular Imaging, and was continued and completed at UC Davis, Department of Biomedical Engineering.

System Performance Simulations of the RatCAP Awake Rat Brain Scanner

NASA Astrophysics Data System (ADS)

Shokouhi, S.; Vaska, P.; Schlyer, D. J.; Stoll, S. P.; Villanueva, A.; Kriplani, A.; Woody, C. L.

2005-10-01

The capability to create high quality images from data acquired by the Rat Conscious Animal PET tomograph (RatCAP) has been evaluated using modified versions of the PET Monte Carlo code Simulation System for Emission Tomography (SimSET). The proposed tomograph consists of lutetium oxyorthosilicate (LSO) crystals arranged in 12 4 /spl times/ 8 blocks. The effects of the RatCAPs small ring diameter (/spl sim/40 mm) and its block detector geometry on image quality for small animal studies have been investigated. Since the field of view will be almost as large as the ring diameter, radial elongation artifacts due to parallax error are expected to degrade the spatial resolution and thus the image quality at the edge of the field of view. In addition to Monte Carlo simulations, some preliminary results of experimentally acquired images in both two-dimensional (2-D) and 3-D modes are presented.

Diode-pumped dual-wavelength Nd:LSO laser at 1059 and 1067  nm with nearly diffraction-limited beam quality.

PubMed

Huang, Xiaoxu; Lan, Jinglong; Lin, Zhi; Wang, Yi; Xu, Bin; Xu, Huiying; Cai, Zhiping; Xu, Xiaodong; Zhang, Jian; Xu, Jun

2016-04-10

We report a diode-pumped continuous-wave simultaneous dual-wavelength Nd:LSO laser at 1059 and 1067 nm. By employing a specially coated output coupler with relatively high transmissions at high-gain emission lines of 1075 and 1079 nm, the two low-gain emission lines, 1059 and 1067 nm, can be achieved, for the first time to our knowledge, with maximum output power of 1.27 W and slope efficiency of about 29.2%. The output power is only limited by the available pump power. Output beam quality is also measured to be about 1.19 and 1.21 of the beam propagation factors in the x and y directions, respectively.

Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner.

PubMed

Catana, Ciprian; Wu, Yibao; Judenhofer, Martin S; Qi, Jinyi; Pichler, Bernd J; Cherry, Simon R

2006-12-01

PET and MRI are powerful imaging techniques that are largely complementary in the information they provide. We have designed and built a MR-compatible PET scanner based on avalanche photodiode technology that allows simultaneous acquisition of PET and MR images in small animals. The PET scanner insert uses magnetic field-insensitive, position-sensitive avalanche photodiode (PSAPD) detectors coupled, via short lengths of optical fibers, to arrays of lutetium oxyorthosilicate (LSO) scintillator crystals. The optical fibers are used to minimize electromagnetic interference between the radiofrequency and gradient coils and the PET detector system. The PET detector module components and the complete PET insert assembly are described. PET data were acquired with and without MR sequences running, and detector flood histograms were compared with the ones generated from the data acquired outside the magnet. A uniform MR phantom was also imaged to assess the effect of the PET detector on the MR data acquisition. Simultaneous PET and MRI studies of a mouse were performed ex vivo. PSAPDs can be successfully used to read out large numbers of scintillator crystals coupled through optical fibers with acceptable performance in terms of energy and timing resolution and crystal identification. The PSAPD-LSO detector performs well in the 7-T magnet, and no visible artifacts are detected in the MR images using standard pulse sequences. The first images from the complete system have been successfully acquired and reconstructed, demonstrating that simultaneous PET and MRI studies are feasible and opening up interesting possibilities for dual-modality molecular imaging studies.

Characterization of the superior olivary complex of Canis lupus domesticus.

PubMed

Fech, Tatiana; Calderón-Garcidueñas, Lilian; Kulesza, Randy J

2017-08-01

The superior olivary complex (SOC) is a collection of brainstem auditory nuclei which play essential roles in the localization of sound sources, temporal coding of vocalizations and descending modulation of the cochlea. Notwithstanding, the SOC nuclei vary considerably between species in accordance with the auditory needs of the animal. The canine SOC was subjected to anatomical and physiological examination nearly 50 years ago and was then virtually forgotten. Herein, we aimed to characterize the nuclei of the canine SOC using quantitative morphometrics, estimation of neuronal number, histochemistry for perineuronal nets and immunofluorescence for the calcium binding proteins calbindin and calretinin. We found the principal nuclei to be extremely well developed: the lateral superior olive (LSO) contained over 20,000 neurons and the medial superior olive (MSO) contained over 15,000 neurons. In nearly all non-chiropterian terrestrial mammals, the MSO exists as a thin, vertical column of neurons. The canine MSO was folded into a U-shaped contour and had associated with the ventromedial tip a small, round collection of neurons we termed the tail nucleus of the MSO. Further, we found evidence within the LSO, MSO and medial nucleus of the trapezoid body (MNTB) for significant morphological variations along the mediolateral or rostrocaudal axes. Finally, the majority of MNTB neurons were calbindin-immunopositive and associated with calretinin-immunopositive calyceal terminals. Together, these observations suggest the canine SOC complies with the basic plan of the mammalian SOC but possesses a number of unique anatomical features. Copyright © 2017 Elsevier B.V. All rights reserved.

Locus-specific oligonucleotide probes increase the usefulness of inter-Alu polymorphisms

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

Jarnik, M.; Tang, J.Q.; Korab-Laskowska, M.

1994-09-01

Most of the mapping approaches are based on single-locus codominant markers of known location. Their multiplex ratio, defined as the number of loci that can be simultaneously tested, is typically one. An increased multiplex ratio was obtained by typing anonymous polymorphisms using PCR primers anchored in ubiquitous Alu-repeats. These so called alumorphs are revealed by inter-Alu-PCR and seen as the presence or absence of an amplified band of a given length. We decided to map alumorphs and to develop locus-specific oligonucleotide (LSO) probes to facilitate their use and transfer among different laboratories. We studied the segregation of alumorphs in eightmore » CEPH families, using two distinct Alu-primers, both directing PCR between the repeats in a tail-to-tail orientation. The segregating bands were assigned to chromosomal locations by two-point linkage analysis with CEPH markers (V6.0). They were excised from dried gels, reamplified, cloned and sequenced. The resulting LSOs were used as hybridization probes (i) to confirm chromosomal assignments in a human/hamster somatic cell hybrid panel, and (ii) to group certain allelic length variants, originally coded as separate dominant markres, into more informative codominant loci. These codominants were then placed by multipoint analysis on a microsatellite Genethon map. Finally, the LSO probes were used as polymorphic STSs, to identify by hybridization the corresponding markers among products of inter-Alu-PCR. The use of LSOs converts alumorphs into a system of non-anonymous, often multiallelic codominant markes which can be simultaneously typed, thus achieving the goal of high multiplex ratio.« less

A RCT comparing lumbosacral orthosis to routine physical therapy on postural stability in patients with chronic low back pain.

PubMed

Azadinia, Fatemeh; Ebrahimi-Takamjani, Ismail; Kamyab, Mojtaba; Parnianpour, Mohamad; Asgari, Morteza

2017-01-01

Background: Poor balance performance and impaired postural control have been frequently reported in patients with low back pain. However, postural control is rarely monitored during the course of treatment even though poor postural control may contribute to chronicity and recurrence of symptoms. Therefore, the present study aimed at investigating the effect of a nonextensible lumbosacral orthosis (LSO) versus routine physical therapy on postural stability of patients with nonspecific chronic low back pain. Methods: This was a randomized controlled trial conducted between November 2015 and May 2016 at the outpatient physical therapy clinic of the School of Rehabilitation Sciences. Patients with nonspecific chronic low back pain aged 20 to 55 years were randomly allocated to the intervention and control groups. Both groups received 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received nonextensible LSO in addition to routine physical therapy. Pain intensity, functional disability, fear of movement/ (re)injury, and postural stability in 3 levels of postural difficulty were measured before and after 4 weeks of intervention. A 2×2×3 mixed model of analysis of variance (ANOVA) was used to determine the main and interactive effects of the 3 factors including group, time, and postural difficulty conditions for each variable of postural stability. Results: The LSO and control groups displayed significant improvement in postural stability at the most difficult postural task conditions (P-value for 95% area ellipse was 0.003; and for phase plane, the mean total velocity and standard deviation of velocity was <0.001). Both groups exhibited a decrease in pain intensity, Oswestry Disability Index, and Tampa Scale of Kinesiophobia after 4 weeks of intervention. A significant difference between groups was found only for functional disability, with greater improvement in the orthosis group (t = 3.60, P<0.001). Conclusion: Both routine physical therapy and LSO significantly improved clinical and postural stability outcomes immediately after 4 weeks of intervention. The orthosis group did not display superior outcomes, except for functional disability.

A RCT comparing lumbosacral orthosis to routine physical therapy on postural stability in patients with chronic low back pain

PubMed Central

Azadinia, Fatemeh; Ebrahimi-Takamjani, Ismail; Kamyab, Mojtaba; Parnianpour, Mohamad; Asgari, Morteza

2017-01-01

Background: Poor balance performance and impaired postural control have been frequently reported in patients with low back pain. However, postural control is rarely monitored during the course of treatment even though poor postural control may contribute to chronicity and recurrence of symptoms. Therefore, the present study aimed at investigating the effect of a nonextensible lumbosacral orthosis (LSO) versus routine physical therapy on postural stability of patients with nonspecific chronic low back pain. Methods: This was a randomized controlled trial conducted between November 2015 and May 2016 at the outpatient physical therapy clinic of the School of Rehabilitation Sciences. Patients with nonspecific chronic low back pain aged 20 to 55 years were randomly allocated to the intervention and control groups. Both groups received 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received nonextensible LSO in addition to routine physical therapy. Pain intensity, functional disability, fear of movement/ (re)injury, and postural stability in 3 levels of postural difficulty were measured before and after 4 weeks of intervention. A 2×2×3 mixed model of analysis of variance (ANOVA) was used to determine the main and interactive effects of the 3 factors including group, time, and postural difficulty conditions for each variable of postural stability. Results: The LSO and control groups displayed significant improvement in postural stability at the most difficult postural task conditions (P-value for 95% area ellipse was 0.003; and for phase plane, the mean total velocity and standard deviation of velocity was <0.001). Both groups exhibited a decrease in pain intensity, Oswestry Disability Index, and Tampa Scale of Kinesiophobia after 4 weeks of intervention. A significant difference between groups was found only for functional disability, with greater improvement in the orthosis group (t = 3.60, P<0.001). Conclusion: Both routine physical therapy and LSO significantly improved clinical and postural stability outcomes immediately after 4 weeks of intervention. The orthosis group did not display superior outcomes, except for functional disability. PMID:29445655

Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam

NASA Astrophysics Data System (ADS)

Hueso-González, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Enghardt, W.; Fiedler, F.; Heidel, K.; Kormoll, T.; Rohling, H.; Schöne, S.; Schwengner, R.; Wagner, A.; Pausch, G.

2014-05-01

In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton accelerators have also been performed and are currently under analysis.

Activity-dependent formation of a vesicular inhibitory amino acid transporter gradient in the superior olivary complex of NMRI mice.

PubMed

Ebbers, Lena; Weber, Maren; Nothwang, Hans Gerd

2017-10-26

In the mammalian superior olivary complex (SOC), synaptic inhibition contributes to the processing of binaural sound cues important for sound localization. Previous analyses demonstrated a tonotopic gradient for postsynaptic proteins mediating inhibitory neurotransmission in the lateral superior olive (LSO), a major nucleus of the SOC. To probe, whether a presynaptic molecular gradient exists as well, we investigated immunoreactivity against the vesicular inhibitory amino acid transporter (VIAAT) in the mouse auditory brainstem. Immunoreactivity against VIAAT revealed a gradient in the LSO and the superior paraolivary nucleus (SPN) of NMRI mice, with high expression in the lateral, low frequency processing limb and low expression in the medial, high frequency processing limb of both nuclei. This orientation is opposite to the previously reported gradient of glycine receptors in the LSO. Other nuclei of the SOC showed a uniform distribution of VIAAT-immunoreactivity. No gradient was observed for the glycine transporter GlyT2 and the neuronal protein NeuN. Formation of the VIAAT gradient was developmentally regulated and occurred around hearing-onset between postnatal days 8 and 16. Congenital deaf Claudin14 -/- mice bred on an NMRI background showed a uniform VIAAT-immunoreactivity in the LSO, whereas cochlear ablation in NMRI mice after hearing-onset did not affect the gradient. Additional analysis of C57Bl6/J, 129/SvJ and CBA/J mice revealed a strain-specific formation of the gradient. Our results identify an activity-regulated gradient of VIAAT in the SOC of NRMI mice. Its absence in other mouse strains adds a novel layer of strain-specific features in the auditory system, i.e. tonotopic organization of molecular gradients. This calls for caution when comparing data from different mouse strains frequently used in studies involving transgenic animals. The presence of strain-specific differences offers the possibility of genetic mapping to identify molecular factors involved in activity-dependent developmental processes in the auditory system. This would provide an important step forward concerning improved auditory rehabilitation in cases of congenital deafness.

Impact of Lu/Gd ratio and activator concentration on structure and scintillation properties of LGSO:Ce crystals

NASA Astrophysics Data System (ADS)

Sidletskiy, O.; Bondar, V.; Grinyov, B.; Kurtsev, D.; Baumer, V.; Belikov, K.; Katrunov, K.; Starzhinsky, N.; Tarasenko, O.; Tarasov, V.; Zelenskaya, O.

2010-02-01

We have studied the dependence of structural and scintillation characteristics of Lu 2 xGd 2-2 xSiO 5:Ce (LGSO:Ce) crystals on cation composition. LGSO:Ce crystals at x=0-1 have been obtained by the Czochralski method. We report here a strong correlation between ionic radii of trivalent cations and their distribution between non-equivalent sites in lattice. By choosing the optimal Lu/Gd ratio and Ce concentration we were able to obtain the light output by˜70%, as compared to LSO:Ce crystals, and energy resolution ˜7 at% 662 KeV ( 137Cs); the afterglow level was decreased by 1-3 orders of magnitude as compared to LSO:Ce. We also discuss the possible mechanisms of control on scintillation characteristics of mixed orthosilicates.

Effective one body approach to the dynamics of two spinning black holes with next-to-leading order spin-orbit coupling

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

Damour, Thibault; Jaranowski, Piotr; Schaefer, Gerhard

2008-07-15

Using a recent, novel Hamiltonian formulation of the gravitational interaction of spinning binaries, we extend the effective one body (EOB) description of the dynamics of two spinning black holes to next-to-leading order (NLO) in the spin-orbit interaction. The spin-dependent EOB Hamiltonian is constructed from four main ingredients: (i) a transformation between the 'effective' Hamiltonian and the 'real' one; (ii) a generalized effective Hamilton-Jacobi equation involving higher powers of the momenta; (iii) a Kerr-type effective metric (with Pade-resummed coefficients) which depends on the choice of some basic 'effective spin vector' S{sub eff}, and which is deformed by comparable-mass effects; and (iv)more » an additional effective spin-orbit interaction term involving another spin vector {sigma}. As a first application of the new, NLO spin-dependent EOB Hamiltonian, we compute the binding energy of circular orbits (for parallel spins) as a function of the orbital frequency, and of the spin parameters. We also study the characteristics of the last stable circular orbit: binding energy, orbital frequency, and the corresponding dimensionless spin parameter a{sub LSO}{identical_to}cJ{sub LSO}/(G(H{sub LSO}/c{sup 2}){sup 2}). We find that the inclusion of NLO spin-orbit terms has a significant 'moderating' effect on the dynamical characteristics of the circular orbits for large and parallel spins.« less

Developmental Emergence of Phenotypes in the Auditory Brainstem Nuclei of Fmr1 Knockout Mice

PubMed Central

Rotschafer, Sarah E.

2017-01-01

Abstract Fragile X syndrome (FXS), the most common monogenic cause of autism, is often associated with hypersensitivity to sound. Several studies have shown abnormalities in the auditory brainstem in FXS; however, the emergence of these auditory phenotypes during development has not been described. Here, we investigated the development of phenotypes in FXS model [Fmr1 knockout (KO)] mice in the ventral cochlear nucleus (VCN), medial nucleus of the trapezoid body (MNTB), and lateral superior olive (LSO). We studied features of the brainstem known to be altered in FXS or Fmr1 KO mice, including cell size and expression of markers for excitatory (VGLUT) and inhibitory (VGAT) synapses. We found that cell size was reduced in the nuclei with different time courses. VCN cell size is normal until after hearing onset, while MNTB and LSO show decreases earlier. VGAT expression was elevated relative to VGLUT in the Fmr1 KO mouse MNTB by P6, before hearing onset. Because glial cells influence development and are altered in FXS, we investigated their emergence in the developing Fmr1 KO brainstem. The number of microglia developed normally in all three nuclei in Fmr1 KO mice, but we found elevated numbers of astrocytes in Fmr1 KO in VCN and LSO at P14. The results indicate that some phenotypes are evident before spontaneous or auditory activity, while others emerge later, and suggest that Fmr1 acts at multiple sites and time points in auditory system development. PMID:29291238

Studies of LSO:Tb radio-luminescence properties using white beam hard X-ray synchrotron irradiation

NASA Astrophysics Data System (ADS)

Cecilia, A.; Rack, A.; Pelliccia, D.; Douissard, P.-A.; Martin, T.; Couchaud, M.; Dupré, K.; Baumbach, T.

A radio-luminescence set-up was installed at the synchrotron light source ANKA to characterise scintillators under the high X-ray photon flux density of white beam synchrotron radiation. The system allows for investigating the radio-luminescence spectrum of the material under study as well as analysing in situ changes of its scintillation behaviour (e.g. under heat load and/or intensive ionising radiation). In this work we applied the radio-luminescence set-up for investigating the radiation damage effects on the luminescence properties of a new kind of thin single crystal scintillator for high resolution X-ray imaging based on a layer of modified Lu2SiO5 grown by liquid phase epitaxy on a dedicated substrate within the framework of an EC project (SCINTAX).

A design of a PET detector using micro-channel plate photomultipliers with transmission-line readout

NASA Astrophysics Data System (ADS)

Kim, H.; Frisch, H.; Chen, C.-T.; Genat, J.-F.; Tang, F.; Moses, W. W.; Choong, W. S.; Kao, C.-M.

2010-10-01

A computer simulation study has been conducted to investigate the feasibility of a positron emission tomography (PET) detector design by using micro-channel plate (MCP) photomultiplier tubes (PMT) with transmission-line (TL) readout and waveform sampling. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each of which was 4×4×25 mm 3 in size, and two 102×102 mm 2 MCP-PMTs coupled to both sides of the scintillator array. The crystal (and TL) pitch was 4.25 mm and reflective medium was inserted between the crystals. The transport of the optical photons inside the scintillator were simulated by using the Geant4 package. The output pulses of the MCP-PMT/TL unit were formed by applying the measured single photo-electron response of the MCP-PMT/TL unit to each individual photon that interacts with the photo-cathode of the MCP-PMT. The waveforms of the pulses at both ends of the TL strips were measured and analyzed to produce energy and timing information for the detected event. An experimental setup was developed by employing a Photonis Planacon MCP-PMT (XP85022) and a prototype TL board for measuring the single photo-electron response of the MCP-PMT/TL. The simulation was validated by comparing the predicted output pulses to measurements obtained with a single MCP-PMT/TL coupled to an LSO crystal exposed to 511 keV gamma rays. The validated simulation was then used to investigate the performance of the proposed new detector design. Our simulation result indicates an energy resolution of ˜11% at 511 keV. When using a 400-600 keV energy window, we obtain a coincidence timing resolution of ˜323 ps FWHM and a coincidence detection efficiency of ˜40% for normally incident 511 keV photons. For the positioning accuracy, it is determined by the pitch of the TLs (and crystals) in the direction normal to the TLs and measured to be ˜2.5 mm in the direction parallel to the TLs. The energy and timing obtained at the front- and back-end of the scintillator array also show differences that are correlated with the depth of interaction of the event.

A Design of a PET Detector Using Micro-Channel Plate Photomultipliers with Transmission-Line Readout.

PubMed

Kim, H; Frisch, H; Chen, C-T; Genat, J-F; Tang, F; Moses, W W; Choong, W S; Kao, C-M

2010-01-01

A computer simulation study has been conducted to investigate the feasibility of a positron emission tomography (PET) detector design by using micro-channel plate (MCP) photomultiplier tubes (PMT) with transmission-line (TL) read-out and waveform sampling. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each of which was 4×4×25 mm(3) in size, and two 102×102 mm(2) MCP-PMTs coupled to both sides of the scintillator array. The crystal (and TL) pitch was 4.25 mm and reflective medium was inserted between the crystals. The transport of the optical photons inside the scintillator were simulated by using the Geant4 package. The output pulses of the MCP-PMT/TL unit were formed by applying the measured single photo-electron response of the MCP-PMT/TL unit to each individual photon that interacts with the photo-cathode of the MCP-PMT. The waveforms of the pulses at both ends of the TL strips were measured and analyzed to produce energy and timing information for the detected event. An experimental setup was developed by employing a Photonis Planacon MCP-PMT (XP85022) and a prototype TL board for measuring the single photo-electron response of the MCP-PMT/TL. The simulation was validated by comparing the predicted output pulses to measurements obtained with a single MCP-PMT/TL coupled to an LSO crystal exposed to 511 keV gamma rays. The validated simulation was then used to investigate the performance of the proposed new detector design. Our simulation result indicates an energy resolution of ~11% at 511 keV. When using a 400-600 keV energy window, we obtain a coincidence timing resolution of ~323 ps FWHM and a coincidence detection efficiency of ~40% for normally-incident 511keV photons. For the positioning accuracy, it is determined by the pitch of the TLs (and crystals) in the direction normal to the TLs and measured to be ~2.5 mm in the direction parallel to the TLs. The energy and timing obtained at the front- and back-end of the scintillator array also show differences that are correlated with the depth of interaction of the event.

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET.

PubMed

Du, Junwei; Schmall, Jeffrey P; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S; Buckley, Steve; Jackson, Carl; Cherry, Simon R

2015-02-01

The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL's front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm(2) and the total size of the detector head is 47.8 × 46.3 mm(2). Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0-32.5 V in 0.5 V intervals) and at different temperatures (5 °C-25 °C in 5 °C degree steps) to find the optimal operating conditions. The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

PubMed Central

Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

2015-01-01

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm2 and the total size of the detector head is 47.8 × 46.3 mm2. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems. PMID:25652479

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

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

Du, Junwei, E-mail: jwdu@ucdavis.edu; Schmall, Jeffrey P.; Yang, Yongfeng

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm{sup 2} and the total size of the detector head is 47.8 × 46.3 mm{sup 2}. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomographymore » (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.« less

Multimodal adaptive optics for depth-enhanced high-resolution ophthalmic imaging

NASA Astrophysics Data System (ADS)

Hammer, Daniel X.; Mujat, Mircea; Iftimia, Nicusor V.; Lue, Niyom; Ferguson, R. Daniel

2010-02-01

We developed a multimodal adaptive optics (AO) retinal imager for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa (RP). The development represents the first ever high performance AO system constructed that combines AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. The SSOCT channel operates at a wavelength of 1 μm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. The system is designed to operate on a broad clinical population with a dual deformable mirror (DM) configuration that allows simultaneous low- and high-order aberration correction. The system also includes a wide field line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation; an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of rotational eye motion; and a high-resolution LCD-based fixation target for presentation to the subject of stimuli and other visual cues. The system was tested in a limited number of human subjects without retinal disease for performance optimization and validation. The system was able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 μm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve targets deep into the choroid. In addition to instrument hardware development, analysis algorithms were developed for efficient information extraction from clinical imaging sessions, with functionality including automated image registration, photoreceptor counting, strip and montage stitching, and segmentation. The system provides clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes.

High-performance electronics for time-of-flight PET systems

NASA Astrophysics Data System (ADS)

Choong, W.-S.; Peng, Q.; Vu, C. Q.; Turko, B. T.; Moses, W. W.

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr3 crystals respectively.

High resolution multimodal clinical ophthalmic imaging system

PubMed Central

Mujat, Mircea; Ferguson, R. Daniel; Patel, Ankit H.; Iftimia, Nicusor; Lue, Niyom; Hammer, Daniel X.

2010-01-01

We developed a multimodal adaptive optics (AO) retinal imager which is the first to combine high performance AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. Such systems are becoming ever more essential to vision research and are expected to prove their clinical value for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa. The SSOCT channel operates at a wavelength of 1 µm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. This AO system is designed for use in clinical populations; a dual deformable mirror (DM) configuration allows simultaneous low- and high-order aberration correction over a large range of refractions and ocular media quality. The system also includes a wide field (33 deg.) line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation, an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of lateral eye motion, and a high-resolution LCD-based fixation target for presentation of visual cues. The system was tested in human subjects without retinal disease for performance optimization and validation. We were able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 µm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve features deep into the choroid. The prototype presented here is the first of a new class of powerful flexible imaging platforms that will provide clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes. PMID:20589021

Eccentric Black Hole Gravitational-wave Capture Sources in Galactic Nuclei: Distribution of Binary Parameters

NASA Astrophysics Data System (ADS)

Gondán, László; Kocsis, Bence; Raffai, Péter; Frei, Zsolt

2018-06-01

Mergers of binary black holes on eccentric orbits are among the targets for second-generation ground-based gravitational-wave detectors. These sources may commonly form in galactic nuclei due to gravitational-wave emission during close flyby events of single objects. We determine the distributions of initial orbital parameters for a population of these gravitational-wave sources. Our results show that the initial dimensionless pericenter distance systematically decreases with the binary component masses and the mass of the central supermassive black hole, and its distribution depends sensitively on the highest possible black hole mass in the nuclear star cluster. For a multi-mass black hole population with masses between 5 {M}ȯ and 80 {M}ȯ , we find that between ∼43–69% (68–94%) of 30 {M}ȯ –30 {M}ȯ (10 M ⊙–10 M ⊙) sources have an eccentricity greater than 0.1 when the gravitational-wave signal reaches 10 Hz, but less than ∼10% of the sources with binary component masses less than 30 {M}ȯ remain eccentric at this level near the last stable orbit (LSO). The eccentricity at LSO is typically between 0.005–0.05 for the lower-mass BHs, and 0.1–0.2 for the highest-mass BHs. Thus, due to the limited low-frequency sensitivity, the six currently known quasicircular LIGO/Virgo sources could still be compatible with this originally highly eccentric source population. However, at the design sensitivity of these instruments, the measurement of the eccentricity and mass distribution of merger events may be a useful diagnostic to identify the fraction of GW sources formed in this channel.

High-performance electronics for time-of-flight PET systems.

PubMed

Choong, W-S; Peng, Q; Vu, C Q; Turko, B T; Moses, W W

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr 3 crystals respectively.

Yb:Lu2SiO5 crystal : characterization of the laser emission along the three dielectric axes

NASA Astrophysics Data System (ADS)

Toci, Guido; Pirri, Angela; Beitlerova, Alena; Shoji, Yasuhiro; Yoshikawa, Akira; Hybler, Jiri; Nikl, Martin; Vannini, Matteo

2015-05-01

Yb:doped Lu2SiO5 (Lutetium orthosilicate, LSO) is an optically biaxial crystal with laser emission in the range 1000- 1100 nm. It features different absorption and emission spectra for polarization along its three dielectric axes. In this work we have characterized the laser emission properties of Yb:LSO along all the three dielectric axis, evidencing differences that can be exploited in the design of ultrafast laser sources. The material was tested in a longitudinally pumped laser cavity. The laser emission efficiency was found similar along all the three dielectric axes, with slope efficiencies around 90% in most cases. Regarding the tuning range, for the most favourable polarization direction we obtained a continuously tunable emission between 993 and 1088 nm (i. e. 95 nm) peaked at 1040 nm. The tuning curves along the three dielectric axes spanned similar ranges but with relevant differences in the shape.

Taking Immersive VR Leap in Training of Landing Signal Officers.

PubMed

Greunke, Larry; Sadagic, Amela

2016-04-01

A major training device used to train all Landing Signal Officers (LSOs) for several decades has been the Landing Signal Officer Trainer, Device 2H111. This simulator, located in Oceana, VA, is contained within a two story tall room; it consists of several large screens and a physical rendition of the actual instruments used by LSOs in their operational environment. The young officers who serve in this specialty will typically encounter this system for only a short period of formal instruction (six one-hour long sessions), leaving multiple gaps in training. While experience with 2H111 is extremely valuable for all LSO officers, the amount of time they can spend using this training device is undeniably too short. The need to provide LSOs with an unlimited number of training opportunities unrestricted by location and time, married with recent advancements in commercial off the shelf (COTS) immersive technologies, provided an ideal platform to create a lightweight training solution that would fill those gaps and extend beyond the capabilities currently offered in the 2H111 simulator. This paper details our efforts on task analysis, surveying of user domain, mapping of 2H111 training capabilities to new prototype system to ensure its support of major training objectives of 2H111, design and development of prototype training system, and a feasibility study that included tests of technical system performance and informal testing with trainees at the LSO Schoolhouse. The results achieved in this effort indicate that the time for LSO training to make the leap to immersive VR has decidedly come.

Simultaneous acquisition of magnetic resonance spectroscopy (MRS) data and positron emission tomography (PET) images with a prototype MR-compatible, small animal PET imager

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Majewski, Stan; Velan, S. Sendhil; Lemieux, Susan; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.

2007-06-01

Multi-modality imaging (such as PET-CT) is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET, fused with anatomical images created by MRI, allow the correlation of form with function. Perhaps more exciting than the combination of anatomical MRI with PET, is the melding of PET with MR spectroscopy (MRS). Thus, two aspects of physiology could be combined in novel ways to produce new insights into the physiology of normal and pathological processes. Our team is developing a system to acquire MRI images and MRS spectra, and PET images contemporaneously. The prototype MR-compatible PET system consists of two opposed detector heads (appropriate in size for small animal imaging), operating in coincidence mode with an active field-of-view of ˜14 cm in diameter. Each detector consists of an array of LSO detector elements coupled through a 2-m long fiber optic light guide to a single position-sensitive photomultiplier tube. The use of light guides allows these magnetic field-sensitive elements of the PET imager to be positioned outside the strong magnetic field of our 3T MRI scanner. The PET scanner imager was integrated with a 12-cm diameter, 12-leg custom, birdcage coil. Simultaneous MRS spectra and PET images were successfully acquired from a multi-modality phantom consisting of a sphere filled with 17 brain relevant substances and a positron-emitting radionuclide. There were no significant changes in MRI or PET scanner performance when both were present in the MRI magnet bore. This successful initial test demonstrates the potential for using such a multi-modality to obtain complementary MRS and PET data.

Comparative effects of sandalwood seed oil on fatty acid profiles and inflammatory factors in rats.

PubMed

Li, Guipu; Singh, Anish; Liu, Yandi; Sunderland, Bruce; Li, Duo

2013-02-01

The aim of the present study was to investigate the effect of sandalwood seed oil on fatty acid (FA) profiles and inflammatory factors in rats. Fifty male Sprague-Dawley rats were randomly divided into five different dietary groups: 10 % soybean oil (SO), 10 % olive oil (OO), 10 % safflower oil (SFO), 10 % linseed oil (LSO) and 8 % sandalwood seed oil blended with 2 % SO (SWSO) for 8 weeks. The SWSO group had a higher total n-3 polyunsaturated fatty acids (PUFA) levels but lower n-6:n-3 PUFA ratios in both adipose tissue and liver than those in the SO, OO and SFO groups (p < 0.05). Although the SWSO group had a much lower 18:3n-3 level (4.51 %) in their dietary lipids than the LSO group (58.88 %), the levels of docosahexaenoic acid (DHA: 22:6n-3) in liver lipids and phospholipids of the SWSO group (7.52 and 11.77 %) were comparable to those of the LSO group (7.07 and 13.16 %). Ximenynic acid, a predominant acetylenic FA in sandalwood seed oil, was found to be highly incorporated into adipose tissue (13.73 %), but relatively lower in liver (0.51 %) in the SWSO group. The levels of prostaglandin F(2α), prostaglandin E₂, thromboxane B₂, leukotriene B₄, tumor necrosis factor-α and interleukin-1β in both liver and plasma were positively correlated with the n-6:n-3 ratios, suggesting that increased n-6 PUFA appear to increase the formation of pro-inflammatory cytokines, whereas n-3 PUFA exhibit anti-inflammatory activity. The present results suggest that sandalwood seed oil could increase tissue levels of n-3 PUFA, DHA and reduce the n-6:n-3 ratio, and may increase the anti-inflammatory activity in rats.

Input-output relationships of the dorsal nucleus of the lateral lemniscus: possible substrate for the processing of dynamic spatial cues.

PubMed

Shneiderman, A; Stanforth, D A; Henkel, C K; Saint Marie, R L

1999-07-26

One organizing principle of the auditory system is the progressive representation of best tuning frequency. Superimposed on this tonotopy are nucleotopic organizations, some of which are related to the processing of different spatial cues. In the present study, we correlated asymmetries in the outputs of the dorsal nucleus of the lateral lemniscus (DNLL) to the two inferior colliculi (ICs), with asymmetries in the inputs to DNLL from the two lateral superior olives (LSOs). The positions of DNLL neurons with crossed and uncrossed projections were plotted from cases with unilateral injections of retrograde tracers in the IC. We found an orderly dorsal-to-ventral progression to the output that recapitulated the tonotopy of DNLL. In addition, we found a nucleotopic organization in the ventral (high-frequency) part of DNLL. Neurons with projections to the ventromedial (high-frequency) part of the contralateral IC were preferentially located ventrolaterally in DNLL; those with projections to the ventromedial part of the ipsilateral IC were preferentially located ventromedially in DNLL. This partial segregation of outputs corresponded with a partial segregation of inputs from the two LSOs in cases which received closely matched bilateral injections of anterograde tracers in LSO. The ventral part of DNLL received a heavy projection medially from the opposite LSO and a heavy projection laterally from the ipsilateral LSO. The findings suggest a direct relationship in the ventral part of the DNLL between inputs from the two LSOs and outputs to the two ICs. Possible roles for this segregation of pathways in DNLL are discussed in relation to the processing of static and dynamic spatial cues.

Long-Term Nightly Treatment with Indiplon in Adults with Primary Insomnia: Results of a Double-Blind, Placebo-Controlled, 3-Month Study

PubMed Central

Scharf, Martin B.; Black, Jed; Hull, Steven; Landin, Rick; Farber, Robert

2007-01-01

Objectives: To evaluate the efficacy and safety of indiplon in primary insomnia. Design: Randomized, double-blind, placebo-controlled, 3-month study. Setting: Multi-center outpatient setting. Patients: N=702 (61% female; mean age 46 years) who met DSM-IV criteria for primary insomnia of at least 3 months' duration. Interventions: Indiplon 10 mg (n=236), indiplon 20 mg (n=233), or placebo (n=233). Measurements: Subjective assessment of each of the following: latency to sleep onset (sLSO), total sleep time (sTST), number of awakenings after sleep onset (sNAASO), wake time after sleep onset (sWASO), sleep quality, Insomnia Severity Index (ISI), and global improvement. Results: Treatment with indiplon resulted in significant improvement relative to placebo at all time points for the primary endpoint, sLSO. Mean sLSO at Month 1 for each treatment group was: 10 mg (34.0 ± 1.3 mins), 20 mg (33.0 ± 1.3 mins), and placebo (48.7 ± 1.9 mins; P <0.0001 for both comparisons); efficacy was sustained through Month 3. Both doses of indiplon resulted in significant improvement in sleep maintenance and duration endpoints, sTST and sWASO, as well as sleep quality, ISI, and global improvement at all assessment time points. Conclusions: In patients with chronic insomnia, long-term nightly treatment with 10 mg and 20 mg doses of indiplon resulted in significant and sustained efficacy in sleep onset, maintenance, and duration, and significant associated improvement in both daytime functioning and quality of life. Citation: Scharf MB; Black J; Hull S et al. Long-term nightly treatment with indiplon in adults with primary insomnia: Results of a double-blind, placebo-controlled, 3-month study. SLEEP 2007;30(6):743-752. PMID:17580596

Docosahexaenoic acid at the sn-2 position of structured triacylglycerols improved n-3 polyunsaturated fatty acid assimilation in tissues of hamsters.

PubMed

Bandarra, Narcisa M; Lopes, Paula A; Martins, Susana V; Ferreira, Júlia; Alfaia, Cristina M; Rolo, Eva A; Correia, Jorge J; Pinto, Rui M A; Ramos-Bueno, Rebeca P; Batista, Irineu; Prates, José A M; Guil-Guerrero, José L

2016-05-01

In this study, we hypothesized that the incorporation of docosahexaenoic acid (DHA) in tissues will be higher when it is ingested as triacylglycerols (TAG) structured at the sn-2 position, which enhances efficacy and health benefits of dietary DHA n-3 supplementation. Ten-week-old Golden Syrian male hamsters were randomly allocated into 4 dietary groups with 10 animals in each: linseed oil (LSO; control group), fish oil (FO), fish oil ethyl esters (FO-EE), and structured DHA at the sn-2 position of TAG (DHA-SL). After 12 weeks, there were no variations in the hamsters' body composition parameters across dietary groups. The DHA-SL diet had the lowest values of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total lipids, and aspartate aminotransferase activity, whereas the inverse was observed for the FO diet. Glucose was increased in the LSO diet without affecting insulin and insulin resistance markers. Whereas n-3 polyunsaturated fatty acid was increased in the brain of hamsters fed the DHA-SL diet, higher levels of n-6 polyunsaturated fatty acid were observed in the liver and erythrocytes of the LSO. The highest omega-3 index was obtained with the DHA-SL diet. The principal component analyses discriminated DHA from other metabolites and set apart 4 clusters matching the 4 diets. Similarly, liver, erythrocytes, and brain were separated from each other, pointing toward an individual signature on fatty acid deposition. The structured sn-2 position DHA-containing TAG ameliorated blood lipids and fatty acid incorporation, in particular eicosapentaenoic acid and DHA in liver, erythrocytes, and brain, relative to commercially FOs, thus improving the health benefits of DHA due to its higher bioavailability. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of dietary fat energy restriction and fish oil feeding on hepatic metabolic abnormalities and insulin resistance in KK mice with high-fat diet-induced obesity.

PubMed

Arai, Takeshi; Kim, Hyoun-ju; Hirako, Satoshi; Nakasatomi, Maki; Chiba, Hiroshige; Matsumoto, Akiyo

2013-01-01

We investigated the effects of dietary fat energy restriction and fish oil intake on glucose and lipid metabolism in female KK mice with high-fat (HF) diet-induced obesity. Mice were fed a lard/safflower oil (LSO50) diet consisting of 50 energy% (en%) lard/safflower oil as the fat source for 12 weeks. Then, the mice were fed various fat energy restriction (25 en% fat) diets - LSO, FO2.5, FO12.5 or FO25 - containing 0, 2.5, 12.5, or 25 en% fish oil, respectively, for 9 weeks. Conversion from a HF diet to each fat energy restriction diet significantly decreased final body weights and visceral and subcutaneous fat mass in all fat energy restriction groups, regardless of fish oil contents. Hepatic triglyceride and cholesterol levels markedly decreased in the FO12.5 and FO25 groups, but not in the LSO group. Although plasma insulin levels did not differ among groups, the blood glucose areas under the curve in the oral glucose tolerance test were significantly lower in the FO12.5 and FO25 groups. Real-time polymerase chain reaction analysis showed fatty acid synthase mRNA levels significantly decreased in the FO25 group, and stearoyl-CoA desaturase 1 mRNA levels markedly decreased in the FO12.5 and FO25 groups. These results demonstrate that body weight gains were suppressed by dietary fat energy restriction even in KK mice with HF diet-induced obesity. We also suggested that the combination of fat energy restriction and fish oil feeding decreased fat droplets and ameliorated hepatic hypertrophy and insulin resistance with suppression of de novo lipogenesis in these mice. Copyright © 2013 Elsevier Inc. All rights reserved.

First report of 'Candidatus Liberibacter solanacearum' on tomato in Honduras

USDA-ARS?s Scientific Manuscript database

In April of 2012, tomato plants grown in several departments of Honduras, were observed with symptoms resembling those of “Candidatus Liberibacter solanacearum” (Lso) infection. The symptoms include overall chlorosis, severe stunting, leaf cupping, excessive branching of axillary shoots, and leaf pu...

Monte Carlo simulation studies on scintillation detectors and image reconstruction of brain-phantom tumors in TOFPET

PubMed Central

Mondal, Nagendra Nath

2009-01-01

This study presents Monte Carlo Simulation (MCS) results of detection efficiencies, spatial resolutions and resolving powers of a time-of-flight (TOF) PET detector systems. Cerium activated Lutetium Oxyorthosilicate (Lu2SiO5: Ce in short LSO), Barium Fluoride (BaF2) and BriLanCe 380 (Cerium doped Lanthanum tri-Bromide, in short LaBr3) scintillation crystals are studied in view of their good time and energy resolutions and shorter decay times. The results of MCS based on GEANT show that spatial resolution, detection efficiency and resolving power of LSO are better than those of BaF2 and LaBr3, although it possesses inferior time and energy resolutions. Instead of the conventional position reconstruction method, newly established image reconstruction (talked about in the previous work) method is applied to produce high-tech images. Validation is a momentous step to ensure that this imaging method fulfills all purposes of motivation discussed by reconstructing images of two tumors in a brain phantom. PMID:20098551

Crystallization conditions and controls on trace element residence in the main minerals from the Pedra Branca Syenite, Brazil: An electron microprobe and LA-ICPMS study

NASA Astrophysics Data System (ADS)

Carvalho, Bruna Borges; Janasi, Valdecir de Assis

2012-11-01

Major and trace-element microanalyses of the main minerals from the 610 Ma Pedra Branca Syenite, southeast Brazil, allow inferences on intensive parameters of magmatic crystallization and on the partition of trace-elements among these minerals, with important implications for the petrogenetic evolution of the pluton. Two main syenite types make up the pluton, a quartz-free syenite with tabular alkali feldspar (laminated silica-saturated syenite, LSS, with Na-rich augite + phlogopite + hematite + magnetite + titanite + apatite) and a quartz-bearing syenite (laminated silica-oversaturated syenite, LSO, with scarce corroded plagioclase plus diopside + biotite ± hornblende + ilmenite ± magnetite + titanite + apatite). Both types share a remarkable enrichment in incompatible elements as K, Ba, Sr, P and LREE. Apatite saturation temperatures of ~ 1060-1090 °C are the best estimates of liquidus, whereas the pressure of emplacement, based on Al-in-hornblende barometry, is estimated as 3.3 to 4.8 kbar. Although both units crystallized under oxidizing conditions, oxygen fugacity was probably higher in LSS, as shown by higher mg# of the mafic minerals and higher hematite contents in Hem-Ilmss. In contrast with the Ca-bearing alkali-feldspar from LSO, which hosts most of the whole-rock Sr and Pb, virtually Ca-free alkali-feldspar from LSS hosts ~ 50% of whole-rock Sr and ~ 80% of Pb, the remainder of these elements being shared by apatite, pyroxene and titanite. This contrast reflects a strong crystal-chemical control, whereby a higher proportion of an element with similar ratio and charge (Ca2 +) enhances the residence of Sr and Pb in the M-site of alkali feldspar. The more alkaline character of the LSS magma is inferred to have inhibited zircon saturation; Zr + Hf remained in solution until late in the crystallization, and were mostly accommodated in the structure of Ca-Na pyroxene and titanite, which are one order of magnitude richer in these elements compared to the same minerals in LSO, where most of Zr and Hf are inferred to reside in zircon. The REE, Th and U reside mostly in titanite and apatite; D(REE)Tit/Ap raises steadily from 1 to 6 from La to Tb then remains constant up to Lu in the LSO sample; these values are about half as much in the LSS sample, where lower contents of incompatible elements in titanite are attributed to its greater modal abundance and earlier crystallization.

First report of 'Candidatus Liberibacter solanacearum' associated with psylllid-affected tobacco in Honduras

USDA-ARS?s Scientific Manuscript database

Tobacco plants with symptoms resembling those associated with the psyllid Bactericera cockerelli and the bacterium “Candidatus Liberibacter solanacearum” (Lso) were observed in April of 2012 in heavily B. cockerelli-infested commercial fields in the Department of El-Paraíso, Honduras; all cultivars ...

Assessing the likelihood of transmission of ‘Candidatus Liberibacter solanacearum’ to carrot by potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae)

USDA-ARS?s Scientific Manuscript database

‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-limited bacterium that severely affects important Solanaceae and Apiaceae crops, including potato, tomato, pepper, tobacco, carrot and celery. This bacterium is transmitted to solanaceous species by potato psyllid, Bactericera cockerelli, and ...

Comparison of Candiatus Liberibacter solanacearum genomic sequences isolated from carrot psyllids in Scandinavia and potato psyllids from Texas

USDA-ARS?s Scientific Manuscript database

The fastidious prokaryote Candidatus Liberibacter solanacearum (Lso), transmitted by the tomato potato psyllid (Bactericera cockerelli), is associated with the Zebra Chip disease of potato. Plants infected with Liberibacter may experience significant yield losses and these plants also serve as poten...

Performance Characteristics of a New LSO PET/CT Scanner With Extended Axial Field-of-View and PSF Reconstruction

NASA Astrophysics Data System (ADS)

Jakoby, Bjoern W.; Bercier, Yanic; Watson, Charles C.; Bendriem, Bernard; Townsend, David W.

2009-06-01

A new combined lutetium oxyorthosilicate (LSO) PET/CT scanner with an extended axial field-of-view (FOV) of 21.8 cm has been developed (Biograph TruePoint PET/CT with TrueV; Siemens Molecular Imaging) and introduced into clinical practice. The scanner includes the recently announced point spread function (PSF) reconstruction algorithm. The PET components incorporate four rings of 48 detector blocks, 5.4 cm times 5.4 cm in cross-section. Each block comprises a 13 times 13 matrix of 4 times 4 times 20 mm3 elements. Data are acquired with a 4.5 ns coincidence time window and an energy window of 425-650 keV. The physical performance of the new scanner has been evaluated according to the recently revised National Electrical Manufacturers Association (NEMA) NU 2-2007 standard and the results have been compared with a previous PET/CT design that incorporates three rings of block detectors with an axial coverage of 16.2 cm (Biograph TruePoint PET/CT; Siemens Molecular Imaging). In addition to the phantom measurements, patient Noise Equivalent Count Rates (NECRs) have been estimated for a range of patients with different body weights (42-154 kg). The average spatial resolution is the same for both scanners: 4.4 mm (FWHM) and 5.0 mm (FWHM) at 1 cm and 10 cm respectively from the center of the transverse FOV. The scatter fractions of the Biograph TruePoint and Biograph TruePoint TrueV are comparable at 32%. Compared to the three ring design, the system sensitivity and peak NECR with smoothed randoms correction (1R) increase by 82% and 73%, respectively. The increase in sensitivity from the extended axial coverage of the Biograph TruePoint PET/CT with TrueV should allow a decrease in either scan time or injected dose without compromising diagnostic image quality. The contrast improvement with the PSF reconstruction potentially offers enhanced detectability for small lesions.

Examining the role of tuber biochemistry in the development of zebra chip in stored potato tubers

USDA-ARS?s Scientific Manuscript database

Zebra chip disease (ZC), associated with infection by the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso), is an emerging problem for potato growers in the United States, Mexico, and New Zealand. Although potato tubers exhibiting ZC symptoms will be rejected by processors, it remains possible...

The effects of Zebra Chip disease development and bacterial titer on biochemical properties in relation to the time of infection

USDA-ARS?s Scientific Manuscript database

Potato tuber biochemical responses to ‘Candidatus’ Liberibacter solanacearum (Lso), the causal agent of Zebra chip disease, were evaluated both within infected tubers and across different infection dates. Tuber biochemistry also was related to symptom severity and bacterial titer. Symptom severity w...

Smart Systems for Logistics Command and Control (SSLC2)

DTIC Science & Technology

2004-06-01

design options 12 AFRL Risk Abatement (continued) • Awareness of key development projects: • AF Portal • GCSS-AF • TBMCS-UL • Enterprise Data Warehouse ... Logistics Enterprise Architecture • Early identification of Transition Agents 13 Collaboration Partners • AF-ILMM • AMC/A-4 • AFC2ISRC • AFMC LSO

Association of promising germplasm exhibiting tolerance to psyllids, aphids, and zebra chip disease with foliar host chemistry

USDA-ARS?s Scientific Manuscript database

Long term, sustainable management of zebra chip disease of potato, caused by “Candidatus Liberibacter solanacearum” (Lso) and vectored by potato psyllids (Bactericera cockerelli Sulc), will require development of new cultivars resistant or tolerant to infection and/or capable of reducing spread. The...

Candidatus Liberibacter solanacearum' development in Russet Norkotah under commercial storage conditions

USDA-ARS?s Scientific Manuscript database

‘Candidatus Liberibacter solanacearum’ (Lso) is the causal agent of zebra chip (ZC) disease in potato. Following the recent appearance of ZC in the Pacific Northwest region of the US, where waves of the vector arrive towards late-summer and early fall and tubers are stored for future marketing, emph...

[Modification and luminescence properties of transparent Lu2SiO5 : Ce3+ thin-film phosphors].

PubMed

Fan, Yang-Yang; Liu, Xiao-Lin; Gu, Mu; Ni, Chen; Huang, Shi-Ming; Liu, Bo

2011-02-01

To achieve high-spatial-resolution for X-ray imaging and flat panel display, transparent thin-film phosphors have been attracted much attention in recent years. In comparison with conventional powder phosphors, the transparent thin-film phosphors have some outstanding advantages such as high contrast and resolution, superior thermal conductivity and better adhesion. Cerium-doped lutetium oxyorthosilicate Lu2 SiO5 (LSO) is one promising candidate due to its high density (7.4 g x cm(-3)), high light yield (27 300 photons x MeV(-1)), short decay time (40 ns), and excellent chemical stability. The sol-gel method is one of the most important techniques for deposition of functional thin films, because it possesses a number of advantages over conventional film formation techniques, such as low processing temperature, easy coating of large surfaces, homogenous multicomponent films, and cheap equipments. In X-ray imaging application, the thickness of the thin-film phosphor is the most important factor, which can increase X-ray absorption of the film and then strengthen its luminescence intensity. In the present work, transparent LSO : Ce film was successfully prepared using sol-gel method and spin-coating technique by using inorganic salts as raw materials, 2-methoxyethanol as solvent, and poly (ethylene glycol) (PEG) as modifier without inert atmosphere. The effect of PEG on the luminescence properties of the film was investigated in detail. The results indicated that PEG200 played an important role in the formation of LSO : Ce film, improving its quality and luminescent intensity. The film thickness of 0.9 microm was achieved after 5 times of coating. The luminescence properties of the film were studied. Their performances were good, which implied that the film would have promising applications in high-spatial-resolution X-ray imaging and flat panel display devices.

On the oxidation of the three-dimensional aromatics [B(12)X(12)](2-) (X=F, Cl, Br, I).

PubMed

Boeré, René T; Derendorf, Janis; Jenne, Carsten; Kacprzak, Sylwia; Kessler, Mathias; Riebau, Rainer; Riedel, Sebastian; Roemmele, Tracey L; Rühle, Monika; Scherer, Harald; Vent-Schmidt, Thomas; Warneke, Jonas; Weber, Stefan

2014-04-07

The perhalogenated closo-dodecaborate dianions [B12 X12 ](2-) (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6 X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12 H12 ](2-) and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2 ) yielded the corresponding radical anions [B12 X12 ](⋅-) (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12 X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12 Cl12 and [Na(SO2 )6 ][B12 Br12 ]⋅B12 Br12 . Sublimation of the crude reaction products that contained B12 X12 (X=Cl, Br) resulted in pure dark blue B12 Cl12 or decomposition to red B9 Br9 , respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12 X12 ](2-) dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12 X12 ](2-) dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12 X12 ](2-) (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1.68 and +2.29 V (lSO2 , versus ferrocene/ferrocenium (Fc(0/+) ))), the second process is irreversible (with oxidation potentials ranging from +2.63 to +2.71 V (lSO2 , versus Fc(0/+) )). [B12 I12 ](2-) showed a complex oxidation behavior in cyclic voltammetry experiments, presumably owing to decomposition of the cluster anion under release of iodide, which also explains the failure to isolate the respective radical by chemical oxidation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ga-68-DOTATOC: Feasibility of high throughput screening by small animal PET using a clinical high-resolution PET/CT scanner

NASA Astrophysics Data System (ADS)

Hofmann, Michael; Weitzel, Thilo; Krause, Thomas

2006-12-01

As radio peptide tracers have been developed in recent years for the high sensitive detection of neuroendocrine tumors, still the broad application of other peptides to breast and prostate cancer is missing. A rapid screening of new peptides can, in theory, be based on in vivo screening in animals by PET/CT. To test this hypothesis and to asses the minimum screening time needed per animal, we used the application of Ga-68-DOTATOC PET/CT in rats as test system. The Ga-68-DOTATOC yields in a hot spot imaging with minimal background. To delineate liver and spleen, we performed PET/CT of 10 animals on a SIEMENS Biograph 16 LSO HIGHREZ after intravenous injection of 1.5 MBq Ga-68-DOTATOC per animal. Animals were mounted in an '18 slot' holding device and scanned for a single-bed position. The emission times for the PET scan was varied from 1 to 20 min. The images were assessed first for "PET only" and afterwards in PET/CT fusion mode. The detection of the two organs was good at emission times down to 1 min in PET/CT fusion mode. In the "PET only" scans, the liver was clearly to be identified down to 1 min emission in all animals. But the spleen could only be delineated only by 1 min of emission in the PET/CT-fusion mode. In conclusion the screening of "hot spot" enriching peptides is feasible. "PET only" is in terms of delineation of small organs by far inferior to PET/CT fusion. If animal tumors are above a diameter of 10 mm small, animal PET/CT using clinical high resolution scanners will enable rapid screening. Even the determination of bio-distributions becomes feasible by using list mode tools. The time for the whole survey of 18 animals including anesthesia, preparation and mounting was approximately 20 min. By use of several holding devices mounted simultaneously, a survey time of less than 1 h for 180 animals can be expected.

Zebra Chip disease and potato biochemistry: Tuber physiological changes in response to ‘Candidatus Liberibacter solanacearum’ infection over time

USDA-ARS?s Scientific Manuscript database

Zebra chip disease (ZC), putatively caused by ‘Candidatus Liberibacter solanacearum’ (Lso), is of increasing concern to potato production in Mexico, the United States, and New Zealand. However, little is known about host tuber physiological changes that result in ZC symptom formation. This study exp...

Advanced Propulsion for Gun Launched Projectiles and Missiles: Phase 1 - Low Cost Flight Test Platform Development

DTIC Science & Technology

2009-11-30

Son blueberry fields as shown in Figure 113. All FAA and Maine DOT permits were acquired. Richard Willey was the designated LSO (Launch Safety...The launch area is on the Jasper Wyman & Son blueberry fields as shown in Figure 113. FAA and Maine DOT permits are required for flight testing

Characterization and correlation of EPG waveforms of Bactericera cockerelli (Hemiptera: Triozidae): variability in waveform appearance in relation to applied signal

USDA-ARS?s Scientific Manuscript database

The potato psyllid, Bactericera cockerelli, was recently shown to be a vector of “Candidatus Liberibacter solanacearum” (Lso), a phloem-limited bacterium that is the putative causal agent of “Zebra Chip” in potato and unnamed diseases in other solanaceous species. Despite its importance, very little...

A comparative study of the time performance between NINO and FlexToT ASICs

NASA Astrophysics Data System (ADS)

Sarasola, I.; Nemallapudi, M. V.; Gundacker, S.; Sánchez, D.; Gascón, D.; Rato, P.; Marín, J.; Auffray, E.

2017-04-01

Universitat de Barcelona (UB) and CIEMAT have designed the FlexToT ASIC for the front-end readout of SiPM-based scintillator detectors. This ASIC is aimed at time of flight (ToF) positron emission tomography (PET) applications. In this work we have evaluated the time performance of the FlexToT v2 ASIC compared to the NINO ASIC, a fast ASIC developped at CERN. NINO electronics give 64 ps sigma for single-photon time resolution (SPTR) and 93 ps FWHM for coincidence time resolution (CTR) with 2 × 2 × 5 mm3 LSO:Ce,Ca crystals and S13360-3050CS SiPMs. Using the same SiPMs and crystals, the FlexToT v2 ASIC yields 91 ps sigma for SPTR and 123 ps FWHM for CTR. Despite worse time performace than NINO, FlexToT v2 features lower power consumption (11 vs. 27 mW/ch) and linear ToT energy measurement.

Characterization of host plant resistance to zebra chip disease from species-derived potato genotypes and the identification of new sources of zebra chip resistance

USDA-ARS?s Scientific Manuscript database

‘Candidatus Liberibacter solanacearum’ (Lso), an uncultivable phloem-limited phytopathogenic bacterium, is known to be associated with Zebra Chip disease (ZC), which represents a major threat to potato production in the US and elsewhere. This pathogen is transmitted by the phloem-feeding potato psyl...

Post-harvest development of Candidatus Liberibacter solanacearum and its impact on the late-season infected potato tubers, with emphasis on cold storage procedures

USDA-ARS?s Scientific Manuscript database

Zebra Chip (ZC) disease has been a challenge to the potato industry in the Americas for close to two decades. ZC is associated with the vector-borne plant pathogen ‘Candidatus Liberibacter solanacearum’ (Lso), which is transmitted by the potato psyllid Bactericera cockerelli (Hem., Triozidae). Follo...

Glutamate co-transmission from developing medial nucleus of the trapezoid body - Lateral superior olive synapses is cochlear dependent in kanamycin-treated rats

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

Lee, Jae Ho; Pradhan, Jonu; Maskey, Dhiraj

Research highlights: {yields} Glutamate co-transmission is enhanced in kanamycin-treated rats. {yields} VGLUT3 expression is increased in kanamycin-treated rats. {yields} GlyR expression is decreased in kanamycin-treated rats. {yields} GlyR, VGLUT3 expression patterns are asymmetric in unilaterally cochlear ablated rat. -- Abstract: Cochlear dependency of glutamate co-transmission at the medial nucleus of the trapezoid body (MNTB) - the lateral superior olive (LSO) synapses was investigated using developing rats treated with high dose kanamycin. Rats were treated with kanamycin from postnatal day (P) 3 to P8. A scanning electron microscopic study on P9 demonstrated partial cochlear hair cell damage. A whole cell voltagemore » clamp experiment demonstrated the increased glutamatergic portion of postsynaptic currents (PSCs) elicited by MNTB stimulation in P9-P11 kanamycin-treated rats. The enhanced VGLUT3 immunoreactivities (IRs) in kanamycin-treated rats and asymmetric VGLUT3 IRs in the LSO of unilaterally cochlear ablated rats supported the electrophysiologic data. Taken together, it is concluded that glutamate co-transmission is cochlear-dependent and enhanced glutamate co-transmission in kanamycin-treated rats is induced by partial cochlear damage.« less

Tomography of the subducting Cocos plate in central Mexico using data from the installation of a prototype wireless seismic network: Images of a truncated slab

NASA Astrophysics Data System (ADS)

Husker, Allen Leroy, Jr.

The central Mexican subduction zone exhibits an oblique strike of the volcanic arc, the Trans-Mexican Volcanic Belt (TMVB), with respect to the trench, flat-slab subduction, and has no Wadati-Benioff zone. The oblique strike of the TMVB is explained by the changing rate of subduction at the trench. The shape of the slab beyond the flat slab section has been unknown until now due to a lack of seismicity, but inferred by the position of the volcanic arc. Here we use data from the Middle America Seismic Experiment (MASE) to image the slab both with tomography and inverting for a slab temperature model. MASE is a collaboration between the Center for Embedded Networked Sensing (CENS) at UCLA, the Universidad Nacional Autonoma de Mexico (UNAM), and the California Institute of Technology (CIT). The data used in this study was from the MASE seismic network. It consisted of 100 seismic stations running, in a line, every 5-6 km from Acapulco, north through TMVB, and to almost the Gulf of Mexico. Half of the seismic stations were the typical standalone style station. These stations were visited once a month to change memory disks and for maintenance. The other 50 stations were developed to send data wirelessly through the network to a base station where the data is linked to the Internet. The 50 stations, called the Wirelessly Linked Seismological Network (WiLSoN), utilize standard Internet tools and protocols to make it both robust and portable to other systems. WiLSoN is described and compared to the standalone stations. The time to permit and install WiLSoN was double that of the standalone network. However, the benefits of WiLSoN included near real-time data and knowledge of system health as compared to only once a month visits to collect data from the standalone stations. However, the data collected from the standalone sites was more complete than that collected from WiLSoN. The lack of data completeness is attributed to the development of both software and hardware for WiLSoN during the MASE experiment. The MASE data is used to perform a 2D P-wave tomography of the subducting Cocos plate. A seismicity study by Pardo and Suarez (1995) mapped a flat Cocos slab under the North America plate to 190 km inland. Our tomography shows the slab subduction continues from 250 km inland at a much steeper angle of 75°. The slab stops somewhere between 450 km and 550 km depth under the northern Trans-Mexican Volcanic Belt. The Farallon plate, from which the Cocos plate presumably broke, is not seen. P-wave travel times are also inverted for a 2D temperature model of the Cocos slab under Mexico. The temperature model from Davies and Stevenson (1992) is found to have unrealistic values in the case of a thin slab, so the diffusion equation is solved with their initial conditions to correct their solution to remove this limitation. The dipping portion of the slab begins 230 km inland, dip at an angle of 74 degrees from the surface, extend to 500 km depth, and have a thickness of 40 km. The model is extended to 21/2D by assuming the slab is infinite along its width. The strike of the slab is then solved for with the full 3D rays found from ray tracing through the iasp91 model. The strike of the dipping slab is found to be 108° clockwise from north, very similar to the strike of the TMVB. A model of the tectonic history is presented that combines those proposed by Ferrari (2004) and Gorbatov and Fukao (2005). At 25 Ma the volcanic arc moved inland marking the beginning of flat-slab subduction. At the same time a tear between the Cocos and Farallon initiated. The torsion from the tear squeezed the Cocos plate causing a flat-slab geometry. At 12.5 Ma another tear propagated along the flat Cocos slab removing the torsion causing uplift. The removal of the uplift caused the upper portion of the Cocos slab to sink and start rolling back until it reached the position where it is imaged in this study. The lack of a Wadati-Benioff zone is due to no deeper slab end which would normally elevate the deviatoric stress to levels that generate earthquakes.

A novel depth-of-interaction block detector for positron emission tomography using a dichotomous orthogonal symmetry decoding concept.

PubMed

Zhang, Yuxuan; Yan, Han; Baghaei, Hossain; Wong, Wai-Hoi

2016-02-21

Conventionally, a dual-end depth-of-interaction (DOI) block detector readout requires two two-dimensional silicon photomultiplier (SiPM) arrays, one on top and one on the bottom, to define the XYZ positions. However, because both the top and bottom SiPM arrays are reading the same pixels, this creates information redundancy. We propose a dichotomous orthogonal symmetric (DOS) dual-end readout block detector design, which removes this redundancy by reducing the number of SiPMs and still achieves XY and DOI (Z) decoding for positron emission tomography (PET) block detector. Reflecting films are used within the block detector to channel photons going to the top of the block to go only in the X direction, and photons going to the bottom are channeled along the Y direction. Despite the unidirectional channeling on each end, the top readout provides both X and Y information using two one-dimensional SiPM arrays instead of a two-dimensional SiPM array; similarly, the bottom readout also provides both X and Y information with just two one-dimensional SiPM arrays. Thus, a total of four one-dimensional SiPM arrays (4  ×  N SiPMs) are used to decode the XYZ positions of the firing pixels instead of two two-dimensional SiPM arrays (2  ×  N  ×  N SiPMs), reducing the number of SiPM arrays per block from 2N(2) to 4 N for PET/MR or PET/CT systems. Moreover, the SiPM arrays on one end can be replaced by two regular photomultiplier tubes (PMTs), so that a block needs only 2 N SiPMs  +  2 half-PMTs; this hybrid-DOS DOI block detector can be used in PET/CT systems. Monte Carlo simulations were carried out to study the performance of our DOS DOI block detector design, including the XY-decoding quality, energy resolution, and DOI resolution. Both BGO and LSO scintillators were studied. We found that 4 mm pixels were well decoded for 5  ×  5 BGO and 9  ×  9 LSO arrays with 4 to 5 mm DOI resolution and 16-20% energy resolution. By adding light-channel decoding, we modified the DOS design to a high-resolution design, which resolved scintillator pixels smaller than the SiPM dimensions. Detector pixels of 2.4 mm were decoded for 8  ×  8 BGO and 15  ×  15 LSO arrays with 5 mm DOI resolution and 20-23% energy resolution. Time performance was also studied for the 8  ×  8 BGO and 15  ×  15 LSO HR-DOS arrays. The timing resolution for the corner and central crystals is 986  ±  122 ps and 1.89  ±  0.17 μs respectively with BGO, 137  ±  42 ps and 458  ±  67 ps respectively with LSO. Monte Carlo simulations with GATE/Geant4 demonstrated the feasibility of our DOS DOI block detector design. In conclusion, our novel design achieved good performance except the time performance while using fewer SiPMs and supporting electronic channels than the current non-DOI PET detectors. This novel design can significantly reduce the cost, heat, and readout complexity of DOI block detectors for PET/MR/CT systems that don't require the time-of-flight capability.

Preliminary studies of a simultaneous PET/MRI scanner based on the RatCAP small animal tomograph

NASA Astrophysics Data System (ADS)

Woody, C.; Schlyer, D.; Vaska, P.; Tomasi, D.; Solis-Najera, S.; Rooney, W.; Pratte, J.-F.; Junnarkar, S.; Stoll, S.; Master, Z.; Purschke, M.; Park, S.-J.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; O'Connor, P.; Radeka, V.

2007-02-01

We are developing a scanner that will allow simultaneous acquisition of high resolution anatomical data using magnetic resonance imaging (MRI) and quantitative physiological data using positron emission tomography (PET). The approach is based on the technology used for the RatCAP conscious small animal PET tomograph which utilizes block detectors consisting of pixelated arrays of LSO crystals read out with matching arrays of avalanche photodiodes and a custom-designed ASIC. The version of this detector used for simultaneous PET/MRI imaging will be constructed out of all nonmagnetic materials and will be situated inside the MRI field. We have demonstrated that the PET detector and its electronics can be operated inside the MRI, and have obtained MRI images with various detector components located inside the MRI field. The MRI images show minimal distortion in this configuration even where some components still contain traces of certain magnetic materials. We plan to improve on the image quality in the future using completely non-magnetic components and by tuning the MRI pulse sequences. The combined result will be a highly compact, low mass PET scanner that can operate inside an MRI magnet without distorting the MRI image, and can be retrofitted into existing MRI instruments.

Why you should ask your patients about their fishing hobbies.

PubMed

Bakker, C V; Kardaun, S H; Wilting, K R; Diercks, G F H; Horváth, B

2013-09-01

Patients who use immunosuppressive agents, in particular medication that blocks tumour necrosis factor-a, are at risk for mycobacterial infections. Besides the typical Mycobacterium tuberculosis infection, a lso a typical mycobacterial disease may occur. Here we demonstrate two patients with such atypical mycobacterial infection due to swimming and fishing water contact. We propose that patients, before starting with immunosuppressive therapy, are counselled about risk factors for mycobacterial disease.

A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course.

PubMed

Schneider, Florian R; Mann, Alexander B; Konorov, Igor; Delso, Gaspar; Paul, Stephan; Ziegler, Sibylle I

2012-06-01

A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a (22)Na point source and reconstruct different source geometries filled with (18)F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. Copyright © 2011. Published by Elsevier GmbH.

Thin-film-based scintillators for hard x-ray microimaging detectors: the ScinTAX Project

NASA Astrophysics Data System (ADS)

Rack, A.; Cecilia, A.; Douissard, P.-A.; Dupré, K.; Wesemann, V.; Baumbach, T.; Couchaud, M.; Rochet, X.; Riesemeier, H.; Radtke, M.; Martin, T.

2014-09-01

The project ScinTAX developed novel thin scintillating films for the application in high performance X-ray imaging and subsequent introduced new X-ray detectors to the market. To achieve this aim lutetium orthosilicate (LSO) scintillators doped with different activators were grown successfully by liquid phase epitaxy. The high density of LSO (7.4 g/cm3), the effective atomic number (65.2) and the high light yield make this scintillator highly applicable for indirect X-ray detection in which the ionizing radiation is converted into visible light and then registered by a digital detector. A modular indirect detection system has been developed to fully exploit the potential of this thin film scintillator for radiographic and tomographic imaging. The system is compatible for high-resolution imaging with moderate dose as well as adaptable to intense high-dose applications where radiation hard microimaging detectors are required. This proceedings article shall review the achieved performances and technical details on this high-resolution detector system which is now available. A selected example application demonstrates the great potential of the optimized detector system for hard X-ray microimaging, i.e. either to improve image contrast due to the availability of efficient thin crystal films or to reduce the dose to the sample.

High-speed photon-counting x-ray computed tomography system utilizing a multipixel photon counter

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Enomoto, Toshiyuki; Watanabe, Manabu; Hitomi, Keitaro; Takahashi, Kiyomi; Sato, Shigehiro; Ogawa, Akiro; Onagawa, Jun

2009-07-01

High-speed photon counting is useful for discriminating photon energy and for decreasing absorbed dose for patients in medical radiography, and the counting is usable for constructing an x-ray computed tomography (CT) system. A photon-counting x-ray CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation stage, a two-stage controller, a multipixel photon counter (MPPC) module, a 1.0-mm-thick LSO crystal (scintillator), a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeating the linear scanning and the rotation of an object, and projection curves of the object are obtained by the linear scanning using the detector consisting of a MPPC module and the LSO. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The lower level of the photon energy is roughly determined by a comparator circuit in the module, and the unit of the level is the photon equivalent (pe). Thus, the average photon energy of the x-ray spectra increases with increasing the lower-level voltage of the comparator. The maximum count rate was approximately 20 Mcps, and energy-discriminated CT was roughly carried out.

X-ray and gamma ray detector readout system

DOEpatents

Tumer, Tumay O; Clajus, Martin; Visser, Gerard

2010-10-19

A readout electronics scheme is under development for high resolution, compact PET (positron emission tomography) imagers based on LSO (lutetium ortho-oxysilicate, Lu.sub.2SiO.sub.5) scintillator and avalanche photodiode (APD) arrays. The key is to obtain sufficient timing and energy resolution at a low power level, less than about 30 mW per channel, including all required functions. To this end, a simple leading edge level crossing discriminator is used, in combination with a transimpedance preamplifier. The APD used has a gain of order 1,000, and an output noise current of several pA/ Hz, allowing bipolar technology to be used instead of CMOS, for increased speed and power efficiency. A prototype of the preamplifier and discriminator has been constructed, achieving timing resolution of 1.5 ns FWHM, 2.7 ns full width at one tenth maximum, relative to an LSO/PMT detector, and an energy resolution of 13.6% FWHM at 511 keV, while operating at a power level of 22 mW per channel. Work is in progress towards integration of this preamplifier and discriminator with appropriate coincidence logic and amplitude measurement circuits in an ASIC suitable for a high resolution compact PET instrument. The detector system and/or ASIC can also be used for many other applications for medical to industrial imaging.

Initial studies using the RatCAP conscious animal PET tomograph

NASA Astrophysics Data System (ADS)

Woody, C.; Vaska, P.; Schlyer, D.; Pratte, J.-F.; Junnarkar, S.; Park, S.-J.; Stoll, S.; Purschke, M.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; Lee, D.; Schiffer, W.; Dewey, S.; Neill, J.; Kandasamy, A.; O'Connor, P.; Radeka, V.; Fontaine, R.; Lecomte, R.

2007-02-01

The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4×8 array of 2.2×2.2×5 mm 3 LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of ˜14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using 18F-FDG and 11C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP.

Detecting Change in Longitudinal Social Networks

DTIC Science & Technology

2011-01-01

organizational change may cause a manager to investigate the presence of good initiatives and see them through to implementation. On the other hand, terrorist... marketing campaigns and media on social behavior. Initial Construct populations, social and knowledge networks, can be hypothetical or real (Carley...mality Data tic data set f any) are 9 independe easible for th ication probl d, this is simp the radio lso known as e unit as a res significant t

Some Integrated Squared Error Procedures for Multivariate Normal Data,

DTIC Science & Technology

1986-01-01

a lnear regresmion or experimental design model). Our procedures have &lSO been usned wcelyOn non -linear models but we do not addres nan-lnear...of fit, outliers, influence functions, experimental design , cluster analysis, robustness 24L A =TO ACT (VCefme - pvre alli of magsy MW identif by...structured data such as multivariate experimental designs . Several illustrations are provided. * 0 %41 %-. 4.’. * " , -.--, ,. -,, ., -, ’v ’ , " ,,- ,, . -,-. . ., * . - tAma- t

Investigation of Internal Corrosion and Corrosion-Control Alternatives in Commercial Tankships.

DTIC Science & Technology

1981-07-01

high sulfur crude, scale on - the sides of the tank may become impregnated with sulfur. The compound formed is pyrophoric iron sulfide .2 7 The...Stiansen - LisLon Mr. M. Touna AMERICAN IRON & STEEL INSTITUTE NATIONAL ACADEMY OF SCIENCES SHIP RESEARCH COMMITTEEMrR.HStne-Lso Mr. A. Dudley Neff...to contribute to corrosion in a tank. In crude oil, the most significant corrosive component is the hydrogen sulfide which it contains. Most oils

A Method for Semi-quantitative Assessment of Exposure to Pesticides of Applicators and Re-entry Workers: An Application in Three Farming Systems in Ethiopia.

PubMed

Negatu, Beyene; Vermeulen, Roel; Mekonnen, Yalemtshay; Kromhout, Hans

2016-07-01

To develop an inexpensive and easily adaptable semi-quantitative exposure assessment method to characterize exposure to pesticide in applicators and re-entry farmers and farm workers in Ethiopia. Two specific semi-quantitative exposure algorithms for pesticides applicators and re-entry workers were developed and applied to 601 farm workers employed in 3 distinctly different farming systems [small-scale irrigated, large-scale greenhouses (LSGH), and large-scale open (LSO)] in Ethiopia. The algorithm for applicators was based on exposure-modifying factors including application methods, farm layout (open or closed), pesticide mixing conditions, cleaning of spraying equipment, intensity of pesticide application per day, utilization of personal protective equipment (PPE), personal hygienic behavior, annual frequency of application, and duration of employment at the farm. The algorithm for re-entry work was based on an expert-based re-entry exposure intensity score, utilization of PPE, personal hygienic behavior, annual frequency of re-entry work, and duration of employment at the farm. The algorithms allowed estimation of daily, annual and cumulative lifetime exposure for applicators, and re-entry workers by farming system, by gender, and by age group. For all metrics, highest exposures occurred in LSGH for both applicators and female re-entry workers. For male re-entry workers, highest cumulative exposure occurred in LSO farms. Female re-entry workers appeared to be higher exposed on a daily or annual basis than male re-entry workers, but their cumulative exposures were similar due to the fact that on average males had longer tenure. Factors related to intensity of exposure (like application method and farm layout) were indicated as the main driving factors for estimated potential exposure. Use of personal protection, hygienic behavior, and duration of employment in surveyed farm workers contributed less to the contrast in exposure estimates. This study indicated that farmers' and farm workers' exposure to pesticides can be inexpensively characterized, ranked, and classified. Our method could be extended to assess exposure to specific active ingredients provided that detailed information on pesticides used is available. The resulting exposure estimates will consequently be used in occupational epidemiology studies in Ethiopia and other similar countries with few resources. © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Transparent garnet ceramic scintillators for gamma-ray detection

NASA Astrophysics Data System (ADS)

Wang, Yimin; Baldoni, Gary; Rhodes, William H.; Brecher, Charles; Shah, Ananya; Shirwadkar, Urmila; Glodo, Jarek; Cherepy, Nerine; Payne, Stephen

2012-10-01

Lanthanide gallium/aluminum-based garnets have a great potential as host structures for scintillation materials for medical imaging. Particularly attractive features are their high density, chemical radiation stability and more importantly, their cubic structure and isotropic optical properties, which allow them to be fabricated into fully transparent, highperformance polycrystalline optical ceramics. Lutetium/gadolinium aluminum/gallium garnets (described by formulas ((Gd,Lu)3(Al,Ga)5O12:Ce, Gd3(Al,Ga)5O12:Ce and Lu3Al5O12:Pr)) feature high effective atomic number and good scintillation properties, which make them particularly attractive for Positron Emission Tomography (PET) and other γ- ray detection applications. The ceramic processing route offers an attractive alternative to single crystal growth for obtaining scintillator materials at relatively low temperatures and at a reasonable cost, with flexibility in dimension control as well as activator concentration adjustment. In this study, optically transparent polycrystalline ceramics mentioned above were prepared by the sintering-HIP approach, employing nano-sized starting powders. The properties and microstructures of the ceramics were controlled by varying the processing parameters during consolidation. Single-phase, high-density, transparent specimens were obtained after sintering followed by a pressure-assisted densification process, i.e. hot-isostatic-pressing. The transparent ceramics displayed high contact and distance transparency as well as high light yield as high as 60,000-65,000 ph/MeV under gamma-ray excitation, which is about 2 times that of a LSO:Ce single crystal. The excellent scintillation and optical properties make these materials promising candidates for medical imaging and γ-ray detection applications.

Monte Carlo simulations of time-of-flight PET with double-ended readout: calibration, coincidence resolving times and statistical lower bounds

PubMed Central

Derenzo, Stephen E

2017-01-01

This paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) double-ended readout for depth-of-interaction information, (3) fixed-level analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depth-dependent timing corrections. Another Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depth-dependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3 × 3 × 30 mm3 scintillators: Lu2SiO5:Ce,Ca (LSO), LaBr3:Ce, and a hypothetical ultra-fast scintillator. To isolate the factors that depend on the scintillator length and the ability to estimate the DOI, CRT values are tabulated for perfect scintillator-photodetectors. For LSO with 4000 photoelectrons and single photoelectron time jitter of the photodetector J = 0.2 ns (FWHM), the CRT value using the statistically weighted average of corrected trigger times is 0.098 ns FWHM and the statistical lower bound is 0.091 ns FWHM. For LaBr3:Ce with 8000 photoelectrons and J = 0.2 ns FWHM, the CRT values are 0.070 and 0.063 ns FWHM, respectively. For the ultra-fast scintillator with 1 ns decay time, 4000 photoelectrons, and J = 0.2 ns FWHM, the CRT values are 0.021 and 0.017 ns FWHM, respectively. The examples also show that calibration and correction for depth-dependent variations in pulse height and in annihilation and optical photon transit times are necessary to achieve these CRT values. PMID:28327464

Monte Carlo simulations of time-of-flight PET with double-ended readout: calibration, coincidence resolving times and statistical lower bounds

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

Derenzo, Stephen E.

Here, this paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) double-ended readout for depth-of-interaction information, (3) fixed-level analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depth-dependent timing corrections. Anothermore » Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depth-dependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3 × 3 × 30 mm 3 scintillators: Lu 2SiO 5 :Ce,Ca (LSO), LaBr 3:Ce, and a hypothetical ultra-fast scintillator. To isolate the factors that depend on the scintillator length and the ability to estimate the DOI, CRT values are tabulated for perfect scintillator-photodetectors. For LSO with 4000 photoelectrons and single photoelectron time jitter of the photodetector J = 0.2 ns (FWHM), the CRT value using the statistically weighted average of corrected trigger times is 0.098 ns FWHM and the statistical lower bound is 0.091 ns FWHM. For LaBr 3:Ce with 8000 photoelectrons and J = 0.2 ns FWHM, the CRT values are 0.070 and 0.063 ns FWHM, respectively. For the ultra-fast scintillator with 1 ns decay time, 4000 photoelectrons, and J = 0.2 ns FWHM, the CRT values are 0.021 and 0.017 ns FWHM, respectively. Lastly, the examples also show that calibration and correction for depth-dependent variations in pulse height and in annihilation and optical photon transit times are necessary to achieve these CRT values.« less

Monte Carlo simulations of time-of-flight PET with double-ended readout: calibration, coincidence resolving times and statistical lower bounds

DOE PAGES

Derenzo, Stephen E.

2017-04-11

Here, this paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) double-ended readout for depth-of-interaction information, (3) fixed-level analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depth-dependent timing corrections. Anothermore » Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depth-dependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3 × 3 × 30 mm 3 scintillators: Lu 2SiO 5 :Ce,Ca (LSO), LaBr 3:Ce, and a hypothetical ultra-fast scintillator. To isolate the factors that depend on the scintillator length and the ability to estimate the DOI, CRT values are tabulated for perfect scintillator-photodetectors. For LSO with 4000 photoelectrons and single photoelectron time jitter of the photodetector J = 0.2 ns (FWHM), the CRT value using the statistically weighted average of corrected trigger times is 0.098 ns FWHM and the statistical lower bound is 0.091 ns FWHM. For LaBr 3:Ce with 8000 photoelectrons and J = 0.2 ns FWHM, the CRT values are 0.070 and 0.063 ns FWHM, respectively. For the ultra-fast scintillator with 1 ns decay time, 4000 photoelectrons, and J = 0.2 ns FWHM, the CRT values are 0.021 and 0.017 ns FWHM, respectively. Lastly, the examples also show that calibration and correction for depth-dependent variations in pulse height and in annihilation and optical photon transit times are necessary to achieve these CRT values.« less

Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion-beam therapy monitoring.

PubMed

Kurz, Christopher; Bauer, Julia; Conti, Maurizio; Guérin, Laura; Eriksson, Lars; Parodi, Katia

2015-07-01

External beam radiotherapy with protons and heavier ions enables a tighter conformation of the applied dose to arbitrarily shaped tumor volumes with respect to photons, but is more sensitive to uncertainties in the radiotherapeutic treatment chain. Consequently, an independent verification of the applied treatment is highly desirable. For this purpose, the irradiation-induced β(+)-emitter distribution within the patient is detected shortly after irradiation by a commercial full-ring positron emission tomography/x-ray computed tomography (PET/CT) scanner installed next to the treatment rooms at the Heidelberg Ion-Beam Therapy Center (HIT). A major challenge to this approach is posed by the small number of detected coincidences. This contribution aims at characterizing the performance of the used PET/CT device and identifying the best-performing reconstruction algorithm under the particular statistical conditions of PET-based treatment monitoring. Moreover, this study addresses the impact of radiation background from the intrinsically radioactive lutetium-oxyorthosilicate (LSO)-based detectors at low counts. The authors have acquired 30 subsequent PET scans of a cylindrical phantom emulating a patientlike activity pattern and spanning the entire patient counting regime in terms of true coincidences and random fractions (RFs). Accuracy and precision of activity quantification, image noise, and geometrical fidelity of the scanner have been investigated for various reconstruction algorithms and settings in order to identify a practical, well-suited reconstruction scheme for PET-based treatment verification. Truncated listmode data have been utilized for separating the effects of small true count numbers and high RFs on the reconstructed images. A corresponding simulation study enabled extending the results to an even wider range of counting statistics and to additionally investigate the impact of scatter coincidences. Eventually, the recommended reconstruction scheme has been applied to exemplary postirradiation patient data-sets. Among the investigated reconstruction options, the overall best results in terms of image noise, activity quantification, and accurate geometrical recovery were achieved using the ordered subset expectation maximization reconstruction algorithm with time-of-flight (TOF) and point-spread function (PSF) information. For this algorithm, reasonably accurate (better than 5%) and precise (uncertainty of the mean activity below 10%) imaging can be provided down to 80,000 true coincidences at 96% RF. Image noise and geometrical fidelity are generally improved for fewer iterations. The main limitation for PET-based treatment monitoring has been identified in the small number of true coincidences, rather than the high intrinsic random background. Application of the optimized reconstruction scheme to patient data-sets results in a 25% - 50% reduced image noise at a comparable activity quantification accuracy and an improved geometrical performance with respect to the formerly used reconstruction scheme at HIT, adopted from nuclear medicine applications. Under the poor statistical conditions in PET-based treatment monitoring, improved results can be achieved by considering PSF and TOF information during image reconstruction and by applying less iterations than in conventional nuclear medicine imaging. Geometrical fidelity and image noise are mainly limited by the low number of true coincidences, not the high LSO-related random background. The retrieved results might also impact other emerging PET applications at low counting statistics.

Military Review, October 1991. Volume 71, Number 10

DTIC Science & Technology

1991-10-01

National Guard Ueutenant Colonel Juan M. Gallardo Chilean Army Spanish Edition 45 Senior Leader Vision: The Case of By Order of the Secretary of the...sobering. Our Army and our nation de- in the 1986 version of FvI 100-5 is largely con- mand our full attention. MR NOTES 1 Michael Howard, "Military...of our victory in serving full time in selected key positions. Tiev L-the gulf, we should ,lso realize that the war provide an internal structure

Monte Carlo simulation of simultaneous radiation detection in the hybrid tomography system ClearPET-XPAD3/CT

NASA Astrophysics Data System (ADS)

Dávila, H. Olaya; Sevilla, A. C.; Castro, H. F.; Martínez, S. A.

2016-07-01

Using the Geant4 based simulation framework SciFW1, a detailed simulation was performed for a detector array in the hybrid tomography prototype for small animals called ClearPET / XPAD, which was built in the Centre de Physique des Particules de Marseille. The detector system consists of an array of phoswich scintillation detectors: LSO (Lutetium Oxy-ortosilicate doped with cerium Lu2SiO5:Ce) and LuYAP (Lutetium Ortoaluminate of Yttrium doped with cerium Lu0.7Y0.3AlO3:Ce) for Positron Emission Tomography (PET) and hybrid pixel detector XPAD for Computed Tomography (CT). Simultaneous acquisition of deposited energy and the corresponding time - position for each recorded event were analyzed, independently, for both detectors. interference between detection modules for PET and CT. Information about amount of radiation reaching each phoswich crystal and XPAD detector using a phantom in order to study the effectiveness by radiation attenuation and influence the positioning of the radioactive source 22Na was obtained. The simulation proposed will improve distribution of detectors rings and interference values will be taken into account in the new versions of detectors.

Sensitivity booster for DOI-PET scanner by utilizing Compton scattering events between detector blocks

NASA Astrophysics Data System (ADS)

Yoshida, Eiji; Tashima, Hideaki; Yamaya, Taiga

2014-11-01

In a conventional PET scanner, coincidence events are measured with a limited energy window for detection of photoelectric events in order to reject Compton scatter events that occur in a patient, but Compton scatter events caused in detector crystals are also rejected. Scatter events within the patient causes scatter coincidences, but inter crystal scattering (ICS) events have useful information for determining an activity distribution. Some researchers have reported the feasibility of PET scanners based on a Compton camera for tracing ICS into the detector. However, these scanners require expensive semiconductor detectors for high-energy resolution. In the Anger-type block detector, single photons interacting with multiple detectors can be obtained for each interacting position and complete information can be gotten just as for photoelectric events in the single detector. ICS events in the single detector have been used to get coincidence, but single photons interacting with multiple detectors have not been used to get coincidence. In this work, we evaluated effect of sensitivity improvement using Compton kinetics in several types of DOI-PET scanners. The proposed method promises to improve the sensitivity using coincidence events of single photons interacting with multiple detectors, which are identified as the first interaction (FI). FI estimation accuracy can be improved to determine FI validity from the correlation between Compton scatter angles calculated on the coincidence line-of-response. We simulated an animal PET scanner consisting of 42 detectors. Each detector block consists of three types of scintillator crystals (LSO, GSO and GAGG). After the simulation, coincidence events are added as information for several depth-of-interaction (DOI) resolutions. From the simulation results, we concluded the proposed method promises to improve the sensitivity considerably when effective atomic number of a scintillator is low. Also, we showed that FI estimate accuracy is improved, as DOI resolution is high.

The Baby Boomers' intergenerational relationships.

PubMed

Fingerman, Karen L; Pillemer, Karl A; Silverstein, Merril; Suitor, J Jill

2012-04-01

As Baby Boomers enter late life, relationships with family members gain importance. This review article highlights two aspects of their intergenerational relationships: (a) caregiving for aging parents and (b) interactions with adult children in the context of changing marital dynamics. The researchers describe three studies: (a) the Within Family Differences Study (WFDS) of mothers aged 65-75 and their multiple grown children (primarily Baby Boomers) ongoing since 2001; (b) the Family Exchanges Study (FES) of Baby Boomers aged 42-60, their spouses, parents, and multiple grown children ongoing since 2008; and (c) the Longitudinal Study of Generations (LSoG) of 351 three-generation families started when the Baby Boomers were teenagers in 1971, with interviews every 3-5 years from 1985 to 2005. These studies show that the Baby Boomers in midlife navigate complex intergenerational patterns. The WFDS finds aging parents differentiate among Baby Boomer children in midlife, favoring some more than others. The FES shows that the Baby Boomers are typically more involved with their children than with their aging parents; Boomers' personal values, family members' needs, and personal rewards shape decisions about support. The LSoG documents how divorce and remarriage dampen intergenerational obligations in some families. Moreover, loosening cultural norms have weakened family bonds in general. Reviews of these studies provide insights into how the Baby Boomers may negotiate caregiving for aging parents as well as the likelihood of family care they will receive when their own health declines in the future.

The Baby Boomers’ Intergenerational Relationships

PubMed Central

Fingerman, Karen L.; Pillemer, Karl A.; Silverstein, Merril; Suitor, J. Jill

2012-01-01

Purpose: As Baby Boomers enter late life, relationships with family members gain importance. This review article highlights two aspects of their intergenerational relationships: (a) caregiving for aging parents and (b) interactions with adult children in the context of changing marital dynamics. Design and Methods: The researchers describe three studies: (a) the Within Family Differences Study (WFDS) of mothers aged 65–75 and their multiple grown children (primarily Baby Boomers) ongoing since 2001; (b) the Family Exchanges Study (FES) of Baby Boomers aged 42–60, their spouses, parents, and multiple grown children ongoing since 2008; and (c) the Longitudinal Study of Generations (LSoG) of 351 three-generation families started when the Baby Boomers were teenagers in 1971, with interviews every 3–5 years from 1985 to 2005. Results: These studies show that the Baby Boomers in midlife navigate complex intergenerational patterns. The WFDS finds aging parents differentiate among Baby Boomer children in midlife, favoring some more than others. The FES shows that the Baby Boomers are typically more involved with their children than with their aging parents; Boomers’ personal values, family members’ needs, and personal rewards shape decisions about support. The LSoG documents how divorce and remarriage dampen intergenerational obligations in some families. Moreover, loosening cultural norms have weakened family bonds in general. Implications: Reviews of these studies provide insights into how the Baby Boomers may negotiate caregiving for aging parents as well as the likelihood of family care they will receive when their own health declines in the future. PMID:22250130

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

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

Cherry, Simon R.; Qi, Jinyi

2012-01-08

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 {micro}m or smaller will lead to an image resolution of 500 {micro}m when using 18F- or 64Cu-labeled radiotracers, giving amore » factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.« less

Pilot Studies With BGO Scintillators Coupled to Low-Noise, Large-Area, SiPM Arrays

NASA Astrophysics Data System (ADS)

González, Antonio J.; Sánchez, Filomeno; Majewski, Stan; Parkhurst, Philip; Vaigneur, Keith; Benlloch, José M.

2016-10-01

Despite the fact that timing capabilities for devices based on BGO are limited when compared with LYSO or LSO based systems, the cost of BGO is considerably lower and could thus, be an option for devices with high scintillator volumes (as in the case of nuclear medicine scanners), but also in smaller dedicated imagers. Recently, many studies have been carried out in order to determine the potential capabilities of BGO for PET and SPECT applications, where BGO scintillator crystals have been coupled to SiPM photosensor devices. However, so far these studies have only been done on small-size BGO samples. In this work, we have studied three different BGO size configurations, coupled to a 12 × 12 low-noise SiPM array. Each SiPM has an active area of 3 × 3 mm2 with a pixel pitch of 4.2 mm. A special charge division network providing information for each row and column output of the SiPM array has been used. The first tested BGO configuration has 2.5 mm crystal pixel pitch and 10 mm thickness, while the second makes use of smaller 1.5 mm pixels with 1.67 mm pitch but only 3 mm thick. The third evaluated configuration provided limited photon depth of interaction (DOI) information by using two staggered layers of BGO pixels also with 2.5 mm pitch and with a total thickness of 20 mm. Performances of these configurations in terms of spatial and energy resolutions have been determined. Energy resolution as good as 14.2% was obtained. Our results indicate that single layer crystal arrays with pixel values as low as 1.5 mm or two staggered layers with 2.5 mm pitch are well suited for PET applications, such as low-cost and high performance dedicated PET systems or large systems.

The Effect of Combat on Aircrew Subjective Readiness and LSO Grades during Operation Desert Shield/Storm.

DTIC Science & Technology

1992-05-01

hours of mission planning and briefing by the same aircrew who later fly into combat. This ’front-loading’ of naval aviators, in advance of flying, may...CaCOLLATERAL DUTIES 080OIDRILks 8,, SLEEP 0 BRIEF 11 STRIKE PLANNING ESEXERCOIE DATE MU MEALS D.DESAOF AvRECAEATIONUREST XYTESTING1 1.1 IT I I- I I 1 l I I1 I... PMCF ) were also inciuded among the TRG flights, although they do not necessarily involve training. When F-14 aircrew were not participating in TRG

The Effect of Combat on Aircrew Subjective Readiness and LSO Grades during Operation Desert Shield/Storm.

DTIC Science & Technology

1992-05-01

These periods of SUSOPS often require many hours of mission planning and briefing by the same aircrew who later fly into combat. This ’front-loading’ of...CsCOLLATERIAL OUTr. GDUTIDIES a au LE.P Sa PlKF PoSTRIKE PLANNING EXEsERCISE DATE MUEAS 0aEMMF PsMEOCEATIONIMEST XETESTING!11 11 I1illilll ii I-. II...duration and infrequent occurrence, functional check flights (FCF) and post maintenance check flights ( PMCF ) were also included among the TRG flights

The SAFIR experiment: Concept, status and perspectives

NASA Astrophysics Data System (ADS)

Becker, Robert; Buck, Alfred; Casella, Chiara; Dissertori, Günther; Fischer, Jannis; Howard, Alexander; Ito, Mikiko; Khateri, Parisa; Lustermann, Werner; Oliver, Josep F.; Röser, Ulf; Warnock, Geoffrey; Weber, Bruno

2017-02-01

The SAFIR development represents a novel Positron Emission Tomography (PET) detector, conceived for preclinical fast acquisitions inside the bore of a Magnetic Resonance Imaging (MRI) scanner. The goal is hybrid and simultaneous PET/MRI dynamic studies at unprecedented temporal resolutions of a few seconds. The detector relies on matrices of scintillating LSO-based crystals coupled one-to-one with SiPM arrays and readout by fast ASICs with excellent timing resolution and high rate capabilities. The paper describes the detector concept and the initial results in terms of simulations and characterisation measurements.

Semiconductor radiation detector with internal gain

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

Iwanczyk, Jan; Patt, Bradley E.; Vilkelis, Gintas

An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

Precision Crystal Calorimeters in High Energy Physics

ScienceCinema

Ren-Yuan Zhu

2017-12-09

Precision crystal calorimeters traditionally play an important role in high energy physics experiments. In the last two decades, it faces a challenge to maintain its precision in a hostile radiation environment. This paper reviews the performance of crystal calorimeters constructed for high energy physics experiments and the progress achieved in understanding crystal’s radiation damage as well as in developing high quality scintillating crystals for particle physics. Potential applications of new generation scintillating crystals of high density and high light yield, such as LSO and LYSO, in particle physics experiments is also discussed.

Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion-beam therapy monitoring

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

Kurz, Christopher, E-mail: Christopher.Kurz@physik.uni-muenchen.de; Bauer, Julia; Conti, Maurizio

Purpose: External beam radiotherapy with protons and heavier ions enables a tighter conformation of the applied dose to arbitrarily shaped tumor volumes with respect to photons, but is more sensitive to uncertainties in the radiotherapeutic treatment chain. Consequently, an independent verification of the applied treatment is highly desirable. For this purpose, the irradiation-induced β{sup +}-emitter distribution within the patient is detected shortly after irradiation by a commercial full-ring positron emission tomography/x-ray computed tomography (PET/CT) scanner installed next to the treatment rooms at the Heidelberg Ion-Beam Therapy Center (HIT). A major challenge to this approach is posed by the small numbermore » of detected coincidences. This contribution aims at characterizing the performance of the used PET/CT device and identifying the best-performing reconstruction algorithm under the particular statistical conditions of PET-based treatment monitoring. Moreover, this study addresses the impact of radiation background from the intrinsically radioactive lutetium-oxyorthosilicate (LSO)-based detectors at low counts. Methods: The authors have acquired 30 subsequent PET scans of a cylindrical phantom emulating a patientlike activity pattern and spanning the entire patient counting regime in terms of true coincidences and random fractions (RFs). Accuracy and precision of activity quantification, image noise, and geometrical fidelity of the scanner have been investigated for various reconstruction algorithms and settings in order to identify a practical, well-suited reconstruction scheme for PET-based treatment verification. Truncated listmode data have been utilized for separating the effects of small true count numbers and high RFs on the reconstructed images. A corresponding simulation study enabled extending the results to an even wider range of counting statistics and to additionally investigate the impact of scatter coincidences. Eventually, the recommended reconstruction scheme has been applied to exemplary postirradiation patient data-sets. Results: Among the investigated reconstruction options, the overall best results in terms of image noise, activity quantification, and accurate geometrical recovery were achieved using the ordered subset expectation maximization reconstruction algorithm with time-of-flight (TOF) and point-spread function (PSF) information. For this algorithm, reasonably accurate (better than 5%) and precise (uncertainty of the mean activity below 10%) imaging can be provided down to 80 000 true coincidences at 96% RF. Image noise and geometrical fidelity are generally improved for fewer iterations. The main limitation for PET-based treatment monitoring has been identified in the small number of true coincidences, rather than the high intrinsic random background. Application of the optimized reconstruction scheme to patient data-sets results in a 25% − 50% reduced image noise at a comparable activity quantification accuracy and an improved geometrical performance with respect to the formerly used reconstruction scheme at HIT, adopted from nuclear medicine applications. Conclusions: Under the poor statistical conditions in PET-based treatment monitoring, improved results can be achieved by considering PSF and TOF information during image reconstruction and by applying less iterations than in conventional nuclear medicine imaging. Geometrical fidelity and image noise are mainly limited by the low number of true coincidences, not the high LSO-related random background. The retrieved results might also impact other emerging PET applications at low counting statistics.« less

Monte Carlo simulations of time-of-flight PET with double-ended readout: calibration, coincidence resolving times and statistical lower bounds

NASA Astrophysics Data System (ADS)

E Derenzo, Stephen

2017-05-01

This paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) double-ended readout for depth-of-interaction information, (3) fixed-level analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depth-dependent timing corrections. Another Monte Carlo algorithm simulates normal operation using these corrections and determines the CRT. A third Monte Carlo algorithm determines the CRT statistical lower bound by generating a series of random interaction depths, and for each interaction a set of random photoelectron times for each of the two photodetectors. The most likely interaction times are determined by shifting the depth-dependent probability density function to maximize the joint likelihood for all the photoelectron times in each set. Example calculations are tabulated for different numbers of photoelectrons and photodetector time jitters for three 3  ×  3  ×  30 mm3 scintillators: Lu2SiO5:Ce,Ca (LSO), LaBr3:Ce, and a hypothetical ultra-fast scintillator. To isolate the factors that depend on the scintillator length and the ability to estimate the DOI, CRT values are tabulated for perfect scintillator-photodetectors. For LSO with 4000 photoelectrons and single photoelectron time jitter of the photodetector J  =  0.2 ns (FWHM), the CRT value using the statistically weighted average of corrected trigger times is 0.098 ns FWHM and the statistical lower bound is 0.091 ns FWHM. For LaBr3:Ce with 8000 photoelectrons and J  =  0.2 ns FWHM, the CRT values are 0.070 and 0.063 ns FWHM, respectively. For the ultra-fast scintillator with 1 ns decay time, 4000 photoelectrons, and J  =  0.2 ns FWHM, the CRT values are 0.021 and 0.017 ns FWHM, respectively. The examples also show that calibration and correction for depth-dependent variations in pulse height and in annihilation and optical photon transit times are necessary to achieve these CRT values.

A chemical potentiator of copper-accumulation used to investigate the iron-regulons of Saccharomyces cerevisiae.

PubMed

Foster, Andrew W; Dainty, Samantha J; Patterson, Carl J; Pohl, Ehmke; Blackburn, Hannah; Wilson, Clare; Hess, Corinna R; Rutherford, Julian C; Quaranta, Laura; Corran, Andy; Robinson, Nigel J

2014-07-01

The extreme resistance of Saccharomyces cerevisiae to copper is overcome by 2-(6-benzyl-2-pyridyl)quinazoline (BPQ), providing a chemical-biology tool which has been exploited in two lines of discovery. First, BPQ is shown to form a red (BPQ)2 Cu(I) complex and promote Ctr1-independent copper-accumulation in whole cells and in mitochondria isolated from treated cells. Multiple phenotypes, including loss of aconitase activity, are consistent with copper-BPQ mediated damage to mitochondrial iron-sulphur clusters. Thus, a biochemical basis of copper-toxicity in S. cerevisiae is analogous to other organisms. Second, iron regulons controlled by Aft1/2, Cth2 and Yap5 that respond to mitochondrial iron-sulphur cluster status are modulated by copper-BPQ causing iron hyper-accumulation via upregulated iron-import. Comparison of copper-BPQ treated, untreated and copper-only treated wild-type and fra2Δ by RNA-seq has uncovered a new candidate Aft1 target-gene (LSO1) and paralogous non-target (LSO2), plus nine putative Cth2 target-transcripts. Two lines of evidence confirm that Fra2 dominates basal repression of the Aft1/2 regulons in iron-replete cultures. Fra2-independent control of these regulons is also observed but CTH2 itself appears to be atypically Fra2-dependent. However, control of Cth2-target transcripts which is independent of CTH2 transcript abundance or of Fra2, is also quantified. Use of copper-BPQ supports a substantial contribution of metabolite repression to iron-regulation. © 2014 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

A chemical potentiator of copper-accumulation used to investigate the iron-regulons of Saccharomyces cerevisiae

PubMed Central

Foster, Andrew W; Dainty, Samantha J; Patterson, Carl J; Pohl, Ehmke; Blackburn, Hannah; Wilson, Clare; Hess, Corinna R; Rutherford, Julian C; Quaranta, Laura; Corran, Andy; Robinson, Nigel J

2014-01-01

The extreme resistance of Saccharomyces cerevisiae to copper is overcome by 2-(6-benzyl-2-pyridyl)quinazoline (BPQ), providing a chemical-biology tool which has been exploited in two lines of discovery. First, BPQ is shown to form a red (BPQ)2Cu(I) complex and promote Ctr1-independent copper-accumulation in whole cells and in mitochondria isolated from treated cells. Multiple phenotypes, including loss of aconitase activity, are consistent with copper-BPQ mediated damage to mitochondrial iron–sulphur clusters. Thus, a biochemical basis of copper-toxicity in S. cerevisiae is analogous to other organisms. Second, iron regulons controlled by Aft1/2, Cth2 and Yap5 that respond to mitochondrial iron–sulphur cluster status are modulated by copper-BPQ causing iron hyper-accumulation via upregulated iron-import. Comparison of copper-BPQ treated, untreated and copper-only treated wild-type and fra2Δ by RNA-seq has uncovered a new candidate Aft1 target-gene (LSO1) and paralogous non-target (LSO2), plus nine putative Cth2 target-transcripts. Two lines of evidence confirm that Fra2 dominates basal repression of the Aft1/2 regulons in iron-replete cultures. Fra2-independent control of these regulons is also observed but CTH2 itself appears to be atypically Fra2-dependent. However, control of Cth2-target transcripts which is independent of CTH2 transcript abundance or of Fra2, is also quantified. Use of copper-BPQ supports a substantial contribution of metabolite repression to iron-regulation. PMID:24895027

Choline acetyltransferase expression during a putative developmental waiting period.

PubMed

Simmons, D D; Bertolotto, C; Kim, J; Raji-Kubba, J; Mansdorf, N

1998-07-27

The relationship between the cholinergic expression, morphological development, and target cell innervation of olivocochlear (OC) efferent neurons was investigated in the postnatal hamster. Similar to what was found in previous studies, tracer injections into the contralateral cochlea labeled cells bodies retrogradely in periolivary regions and labeled cell bodies only rarely in the lateral superior olive (LSO). Few morphological differences were found among cell bodies labeled between postnatal day 1 (P1) and P30. Tracer injections into the crossed OC bundles within the brainstem anterogradely labeled terminals below the inner hair cells of the cochlea prior to P5 and labeled terminals below outer hair cells after P5, consistent with a period of transient innervation, as hypothesized previously. Within the superior olive, choline acetyltransferase (ChAT) was expressed differentially. In periolivary regions, ChAT was expressed as early as P0. ChAT-immunoreactive cell bodies in periolivary regions were similar morphologically to retrogradely labeled OC neurons. In contrast, within the LSO, ChAT was not expressed until after P2. Consistent with a medical OC projection to the cochlea at early postnatal ages, ChAT immunoreactivity was detected below inner hair cells as early as P2 but was not detected below outer hair cells until after P6. Our results suggest that medial OC neurons not only provide transient connections to inner hair cells but also may express ChAT when they are below inner hair cells. Furthermore, these results raise the possibility that OC neurons may be capable of acetylcholine synthesis and release prior to or simultaneous with their innervation of the cochlea.

Early segregation of layered projections from the lateral superior olivary nucleusto the central nucleus of the inferior colliculus in the neonatal cat

PubMed Central

Gabriele, Mark L.; Shahmoradian, Sarah H.; French, Christopher C.; Henkel, Craig K.we; McHaffie, John G.

2007-01-01

The central nucleus of the inferior colliculus (IC) is a laminated structure that receives multiple converging afferent projections. These projections terminate in a layered arrangement and are aligned with dendritic arbors of the predominant disc-shaped neurons, forming fibrodendritic laminae. Within this structural framework, inputs terminate in a precise manner, establishing a mosaic of partially overlapping domains that likely define functional compartments. Although several of these patterned inputs have been described in the adult, relatively little is known about their organization prior to hearing onset. The present study used the lipophilic carbocyanine dyes DiI and DiD to examine the ipsilateral and contralateral projections from the lateral superior olivary (LSO) nucleus to the IC in a developmental series of paraformaldehyde-fixed kitten tissue. By birth, the crossed and uncrossed projections had reached the IC and were distributed across the frequency axis of the central nucleus. At this earliest postnatal stage, projections already exhibited a characteristic banded arrangement similar to that described in the adult. The heaviest terminal fields of the two inputs were always complementary in nature, with the ipsilateral input appearing slightly denser. This early arrangement of interdigitating ipsilateral and contralateral LSO axonal bands that occupy adjacent sublayers supports the idea that the initial establishment of this highly organized mosaic of inputs that defines distinct synaptic domains within the IC occurs largely in the absence of auditory experience. Potential developmental mechanisms that may shape these highly ordered inputs prior to hearing onset are discussed. PMID:17850770

Circuits that Innervate Excitatory-Inhibitory Cells in the Inferior Colliculus Obtained with In-Vivo Whole Cell Recordings

PubMed Central

Li, Na; Pollak, George D.

2013-01-01

Neurons excited by stimulation of one ear and suppressed by the other, called EI neurons, are sensitive to interaural intensity disparities (IIDs), the cues animals use to localize high frequencies. EI neurons are first formed in lateral superior olive (LSO), which then sends excitatory projections to the dorsal nucleus of the lateral lemniscus (DNLL) and the inferior colliculus (IC), both of which contain large populations of EI cells. We evaluate the inputs that innervate EI cells in the IC of Mexican free-tailed bats, Tadarida brasilensis mexicana, with in vivo whole cell recordings from which we derived excitatory and inhibitory conductances. We show that the basic EI property in the majority of IC cells is inherited from LSO, but each type of EI cell is also innervated by the ipsi- or contralateral DNLL, as well as additional excitatory and inhibitory inputs from monaural nuclei. We identify three EI types, where each type receives a set of projections that are different from the other types. To evaluate the role that the various projections played in generating binaural responses, we used modeling to compute a predicted response from the conductances. We then omitted one of the conductances from the computation to evaluate the degree to which that input contributed to the binaural response. We show that formation of the EI property in the various types is complex, and that some projections exert such subtle influences that they could not have been detected with extracellular recordings or even from intracellular recordings of post-synaptic potentials. PMID:23575835

A Central Positron Source to Perform the Timing Alignment of Detectors in a PET Scanner

NASA Astrophysics Data System (ADS)

Thompson, C. J.; Camborde, M.-L.; Casey, M. E.

2005-10-01

Accurate timing alignment and stability are important to maximize the true counts and minimize the random counts in positron emission tomography. Its importance increases in time-of-flight (TOF) scanners. We propose using a central positron emitting source enclosed in a detector which detects the excess energy of the positron before it annihilates as a timing reference. All crystals can be time-aligned with respect to this central source. We evaluated 10 /spl mu/Ci /sup 22/Na and /sup 68/Ge sources embedded in cylinders of plastic scintillator coupled to a fast PMT. Light flashes produced after the parent isotope emits positrons are detected, and the anode signals from the PMT are the reference time for each positron decay. The time delay before the gamma ray is detected by the scanner's conventional gamma ray detectors is the time offset to be applied to that crystal. Since all detectors are almost the same distance from the central source, TOF errors are minimized. Preliminary results show a mean signal amplitude of >0.5 V from /sup 22/Na at 1000-V PMT bias, a timing FWHM of 850 ps with respect to a small LSO crystal. This suggests it could be useful to align both conventional and TOF PET scanners.

Characterisation of crystal matrices and single pixels for nuclear medicine applications

NASA Astrophysics Data System (ADS)

Herbert, D. J.; Belcari, N.; Camarda, M.; Guerra, A. Del; Vaiano, A.

2005-01-01

Commercially constructed crystal matrices are characterised for use with PSPMT detectors for PET system developments and other nuclear medicine applications. The matrices of different scintillation materials were specified with pixel dimensions of 1.5×1.5 mm2 in cross-section and a length corresponding to one gamma ray interaction length at 511 keV. The materials used in this study were BGO, LSO, LYSO, YSO and CsI(Na). Each matrix was constructed using a white TiO loaded epoxy that forms a 0.2 mm septa between each pixel. The white epoxy is not the optimum choice in terms of the reflective properties, but represents a good compromise between cost and the need for optical isolation between pixels. We also tested a YAP matrix that consisted of pixels of the same size specification but was manufactured by a different company, who instead of white epoxy, used a thin aluminium reflective layer for optical isolation that resulted in a septal thickness of just 0.01 mm, resulting in a much higher packing fraction. The characteristics of the scintillation materials, such as the light output and energy resolution, were first studied in the form of individual crystal elements by using a single pixel HPD. A comparison of individual pixels with and without the epoxy/dielectric coatings was also performed. Then the matrices themselves were coupled to a PSPMT in order to study the imaging performance. In particular, the system pixel resolution and the peak to valley ratio were measured at 511 and 122 keV.

A comparative study via Monte Carlo simulation of new inorganic scintillator Cs2HfCl6 for applications in nuclear medicine, security and defense, and astrophysics

NASA Astrophysics Data System (ADS)

Chen, Henry; Raby, Paul

2016-09-01

Cs2HfCl6 (CHC) is one of the most promising recently discovered new inorganic single crystal scintillator that has high light output, non-hygroscopic, no self-activity, having energy resolution significantly better than NaI(Tl), even approaching that of LaBr3 yet can also potentially be at a much lower cost than LaBr3. This study attempts to use Monte Carlo simulation to examine the great potential offered by this new scintillator. CHC's detector performance is compared via simulation with that of 4 typical existing scintillators of the same size and same PMT readout. Two halide-scintillators: NaI(Tl) and LaBr3 and two oxide-scintillators: GSO and LSO were used in this simulation to compare their 122 keV and 511 keV gamma responses with that of CHC with both spectroscopy application and imaging applications in mind. Initial simulation results are very promising and consistent with reported experimental measurements. Beside detector energy resolution, image-quality measurement parameters commonly used to characterize imaging detectors as in nuclear medicine such as Light Response Function (LRF) which goes in parallel with spatial resolution and simulated position spectra will also be presented and discussed.

Next generation PET data acquisition architectures

NASA Astrophysics Data System (ADS)

Jones, W. F.; Reed, J. H.; Everman, J. L.; Young, J. W.; Seese, R. D.

1997-06-01

New architectures for higher performance data acquisition in PET are proposed. Improvements are demanded primarily by three areas of advancing PET state of the art. First, larger detector arrays such as the Hammersmith ECAT/sup (R/) EXACT HR/sup ++/ exceed the addressing capacity of 32 bit coincidence event words. Second, better scintillators (LSO) make depth-of interaction (DOI) and time-of-flight (TOF) operation more practical. Third, fully optimized single photon attenuation correction requires higher rates of data collection. New technologies which enable the proposed third generation Real Time Sorter (RTS III) include: (1) 80 Mbyte/sec Fibre Channel RAID disk systems, (2) PowerPC on both VMEbus and PCI Local bus, and (3) quadruple interleaved DRAM controller designs. Data acquisition flexibility is enhanced through a wider 64 bit coincidence event word. PET methodology support includes DOI (6 bits), TOF (6 bits), multiple energy windows (6 bits), 512/spl times/512 sinogram indexes (18 bits), and 256 crystal rings (16 bits). Throughput of 10 M events/sec is expected for list-mode data collection as well as both on-line and replay histogramming. Fully efficient list-mode storage for each PET application is provided by real-time bit packing of only the active event word bits. Real-time circuits provide DOI rebinning.

Assessment of the Navy’s North West Region Advance Food Menu Gallery Workload and Food Cost Impact Trade-Offs

DTIC Science & Technology

2009-06-01

Self serve Same All All Assorted Indiv Fresh Fruits Bananas , apples, oranges, etc. Self serve Same All B/Br Omelets/Eggs to Order Scratch- from fresh...Prepared by night crew (M-F), and day crew for Saturday and Sunday All B/Br E02401 Assorted Cereal Adv Individual bowls with peel lids M-F L-SO N01207...Fresh Fruit Vegetable Prep [FSAs]  Wash, slice, dice, cut, peel or other process FFV, etc.  Clean/sanitize FFV Prep room equipment.  Clean FFV

Examining the Potential Role of Foliar Chemistry in Imparting Potato Germplasm Tolerance to Potato Psyllid, Green Peach Aphid, and Zebra Chip Disease.

PubMed

Prager, S M; Wallis, C M; Jones, M; Novy, R; Trumble, J T

2018-02-09

Long-term, sustainable management of zebra chip disease of potato, caused by 'Candidatus Liberibacter solanacearum' (Lso) and vectored by potato psyllids (Bactericera cockerelli Sulc [Hemiptera: Triozidae]), requires development of cultivars resistant or tolerant to infection or capable of reducing spread or both. We examined the influence that five experimental breeding clones of potato had on potato psyllids and their ability to vector Lso. The ability of these potato clones to resist aphids (green peach aphids, Myzus persicae Sulzer [Hemiptera: Aphididae]) also was examined. Due to the importance of host chemistry on plant-insect interactions, levels of primary metabolites of amino acids and sugars, as well as secondary metabolites including polyphenolics, terpenoids, and alkaloids were compared between breeding clones and a commercial cultivar. Findings for compound levels then were associated with observed changes in host susceptibility to psyllids or aphids. Psyllids oviposited less on three breeding clones than Atlantic, but no significant effects of breeding clones on psyllid feeding or choice were observed. Aphid reproduction was reduced on two clones relative to Atlantic. A05379-211 had greater sugar levels and postpsyllid amino acid levels than Atlantic. Total alkaloid and phenolic levels were greater in all breeding clones than Atlantic. Total terpenoid levels were greater in PALB03016-3 and PALB03016-6 than Atlantic, which might explain, in part, the observed resistance to psyllid oviposition and aphid reproduction. Overall, these results suggest that increased levels of certain metabolites in breeding clones could affect psyllid and aphid reproduction. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Time-over-threshold for pulse shape discrimination in a time-of-flight phoswich PET detector.

PubMed

Chang, Chen-Ming; Cates, Joshua W; Levin, Craig S

2017-01-07

It is well known that a PET detector capable of measuring both photon time-of-flight (TOF) and depth-of-interaction (DOI) improves the image quality and accuracy. Phoswich designs have been realized in PET detectors to measure DOI for more than a decade. However, PET detectors based on phoswich designs put great demand on the readout circuits, which have to differentiate the pulse shape produced by different crystal layers. A simple pulse shape discrimination approach is required to realize the phoswich designs in a clinical PET scanner, which consists of thousands of scintillation crystal elements. In this work, we studied time-over-threshold (ToT) as a pulse shape parameter for DOI. The energy, timing and DOI performance were evaluated for a phoswich detector design comprising [Formula: see text] mm LYSO:Ce crystal optically coupled to [Formula: see text] mm calcium co-doped LSO:Ce,Ca(0.4%) crystal read out by a silicon photomultiplier (SiPM). A DOI accuracy of 97.2% has been achieved for photopeak events using the proposed time-over-threshold (ToT) processing. The energy resolution without correction for SiPM non-linearity was [Formula: see text]% and [Formula: see text]% FWHM at 511 keV for LYSO and LSO crystal layers, respectively. The coincidence time resolution for photopeak events ranges from 164.6 ps to 183.1 ps FWHM, depending on the layer combinations. The coincidence time resolution for inter-crystal scatter events ranges from 214.6 ps to 418.3 ps FWHM, depending on the energy windows applied. These results show great promises of using ToT for pulse shape discrimination in a TOF phoswich detector since a ToT measurement can be easily implemented in readout electronics.

2008 Evaluation of the DoD Voting Assistance Program

DTIC Science & Technology

2009-04-30

tion reports fro~ VAOs and t he NVAP Web site . We a lso conside red arti cles, NAVADMINs , e;nails fro:n the Navy Vot~ng Act ion Of ficer (NVAOl...a nce. (DODD 133. 1 3) Response : Sixty o f s i xty-seven (83\\) r e cruitme nt o ff ice vo ting personne l c o mp l ete d requ i red training, a s...e: Per OPNAVINST 1 742. 18, VAOs are requ: red to conduct t r ainin-g at t he unit level. Ma n y c ommands c ov e r absen t ee reg i s trat ion and

Retrograde transport of (/sup 3/H)-D-aspartate label by cochlear and vestibular efferent neurons

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

Schwarz, D.W.; Schwarz, I.E.

1988-01-01

(/sup 3/H)-D-aspartic acid was injected into the inner ear of rats. After a six hour survival time, labeled cells were found at all locations known to contain efferent cochlear or vestibular neurons. Most labeled neurons were found in the ipsilateral lateral superior olivary nucleus (LSO), although both ventral nuclei of the trapezoid body (VTB), group E, and the caudal pontine reticular nucleus (CPR) just adjacent to the ascending limb of the facial nerve also contained labeled cells. Because not all efferent neurons in the rat could be previously shown to be cholinergic, aspartate and glutamate are efferent transmitter candidates.

Hazards/Failure Modes and Effects Analysis MK 1 MOD 0 LSO-HUD Console System.

DTIC Science & Technology

1980-03-24

AsI~f~ ! 127 = 3gc Z Isre -0 -q ~sI I I 𔃻~~~ ~ _ _ 3_______ II! -0udC Z Z’ P4 12 d-U * ~s ’:i~i42 S- 60 -, Uh ~ U3l I OM -C ~ . - U 4~ dcd 8U-q Ali...8 VI SCOPE AND METHODOLOGY OF ANALYSIS ........ 1O FIGURE 1: H/ FMEA /(SSA) WORK SHEET FORMAT ........... 14 APPENDIX A: HAZARD/FAILURE MODES AND...EFFECTS ANALYSIS (H/ FMEA ) -- WORK SHEETS ......... 15(A-O) TABLE: SUBSYSTEM: UNIT I Heads-Up Display Console .............. 17(A-1) UNIT 2 Auxiliary

Scintillating screens based on the LPE grown Tb3Al5O12:Ce single crystalline films

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Douissard, Paul-Antoine; Martin, Thierry; Riva, Federica; Gorbenko, Vitaliy; Zorenko, Tetiana; Paprocki, Kazimierz; Iskalieva, Aizhan; Witkiewicz, Sandra; Fedorov, Alexander; Bilski, Paweł; Twardak, Anna

2017-03-01

We report in this work the creation of new heavy and efficient Tb3Al5O12:Ce (TbAG:Ce) single crystalline film (SCF) scintillators, grown by LPE method from PbO-B2O3 based flux onto Y3Al5O12 (YAG) and Gd3Ga2.5Al2.5O12 (GAGG) substrates, for different optoelectronic applications. The luminescent and scintillation properties of the TbAG:Ce SCF screens, grown onto different types of substrates, are studied and compared with the properties of the Lu3Al5O12:Ce (LuAG:Ce) and YAG:Ce SCF counterparts. TbAG:Ce SCFs show very high scintillation light yield (LY) under α-particles excitation, which overcomes by 30% the LY of high-quality LuAG:Ce SCF samples. In comparison with YAG:Ce and LuAG:Ce SCFs, TbAG:Ce SCF screens show also significantly lower afterglow (up to 10-4 level at X-ray burst duration of 0.1 s), which is comparable with the afterglow level of the best samples of LSO:Ce, Tb SCFs typically being used now for microimaging. Together with a high light output of X-ray excited luminescence, such extremely low afterglow of TbAG:Ce SCF is a very good reason for future development of scintillating screens based on the mentioned garnet. We also introduce the possibility to create new types of ;film-substrate; hybrid scintillators using the LPE method for simultaneous registration of different components of ionizing radiation and microimaging based on the TbAG:Ce SCF and GAGG:Ce substrates.

PET Performance Evaluation of an MR-Compatible PET Insert

PubMed Central

Wu, Yibao; Catana, Ciprian; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Qi, Jinyi; Cherry, Simon R.

2010-01-01

A magnetic resonance (MR) compatible positron emission tomography (PET) insert has been developed in our laboratory for simultaneous small animal PET/MR imaging. This system is based on lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiode (PSAPD) photodetectors. The PET performance of this insert has been measured. The average reconstructed image spatial resolution was 1.51 mm. The sensitivity at the center of the field of view (CFOV) was 0.35%, which is comparable to the simulation predictions of 0.40%. The average photopeak energy resolution was 25%. The scatter fraction inside the MRI scanner with a line source was 12% (with a mouse-sized phantom and standard 35 mm Bruker 1H RF coil), 7% (with RF coil only) and 5% (without phantom or RF coil) for an energy window of 350–650 keV. The front-end electronics had a dead time of 390 ns, and a trigger extension dead time of 7.32 μs that degraded counting rate performance for injected doses above ~0.75 mCi (28 MBq). The peak noise-equivalent count rate (NECR) of 1.27 kcps was achieved at 290 μCi (10.7 MBq). The system showed good imaging performance inside a 7-T animal MRI system; however improvements in data acquisition electronics and reduction of the coincidence timing window are needed to realize improved NECR performance. PMID:21072320

Characterization of the LBNL PEM Camera

NASA Astrophysics Data System (ADS)

Wang, G.-C.; Huber, J. S.; Moses, W. W.; Qi, J.; Choong, W.-S.

2006-06-01

We present the tomographic images and performance measurements of the LBNL positron emission mammography (PEM) camera, a specially designed positron emission tomography (PET) camera that utilizes PET detector modules with depth of interaction measurement capability to achieve both high sensitivity and high resolution for breast cancer detection. The camera currently consists of 24 detector modules positioned as four detector banks to cover a rectangular patient port that is 8.2/spl times/6 cm/sup 2/ with a 5 cm axial extent. Each LBNL PEM detector module consists of 64 3/spl times/3/spl times/30 mm/sup 3/ LSO crystals coupled to a single photomultiplier tube (PMT) and an 8/spl times/8 silicon photodiode array (PD). The PMT provides accurate timing, the PD identifies the crystal of interaction, the sum of the PD and PMT signals (PD+PMT) provides the total energy, and the PD/(PD+PMT) ratio determines the depth of interaction. The performance of the camera has been evaluated by imaging various phantoms. The full-width-at-half-maximum (FWHM) spatial resolution changes slightly from 1.9 mm to 2.1 mm when measured at the center and corner of the field of the view, respectively, using a 6 ns coincidence timing window and a 300-750 keV energy window. With the same setup, the peak sensitivity of the camera is 1.83 kcps//spl mu/Ci.

Comparison of SensL and Hamamatsu 4×4 channel SiPM arrays in gamma spectrometry with scintillators

NASA Astrophysics Data System (ADS)

Grodzicka-Kobylka, M.; Szczesniak, T.; Moszyński, M.

2017-06-01

The market of Silicon Photomultipliers (SiPMs) consists of many manufacturers that produce their detectors in different technology. Hamamatsu (Japan) and SensL (Ireland) seems to be the most popular companies that produce large SiPM arrays. The aim of this work is characterization and comparison of 4×4 channel SiPM arrays produced by these two producers. Both of the tested SiPMs are made in through-silicon via (TSV) technology, consist of 16, 3×3 mm avalanche photodiode (APD) cells and have fill factor slightly above 60%. The largest difference is a single APD cell size and hence total number of APD cells (55,424 for Hamamatsu, 76,640 for SensL). In the case of SensL SiPM, its spectral response characteristics is shifted slightly toward shorter wavelengths with maximum at 420 nm (450 nm for Hamamatsu). The presented measurements cover selection of the SiPM optimum operating voltage (in respect to energy resolution), verification of the excess noise factor and check of the linearity characteristics. Moreover, the gamma spectrometry with LSO, BGO and CsI:Tl scintillators together with pulse characteristics for these crystals (rise time and fall time) is reported, as well as temperature dependence. The presented measurements show better performance of the SensL array comparing to the Hamamatsu detector.

A multi-threshold sampling method for TOF-PET signal processing

NASA Astrophysics Data System (ADS)

Kim, H.; Kao, C. M.; Xie, Q.; Chen, C. T.; Zhou, L.; Tang, F.; Frisch, H.; Moses, W. W.; Choong, W. S.

2009-04-01

As an approach to realizing all-digital data acquisition for positron emission tomography (PET), we have previously proposed and studied a multi-threshold sampling method to generate samples of a PET event waveform with respect to a few user-defined amplitudes. In this sampling scheme, one can extract both the energy and timing information for an event. In this paper, we report our prototype implementation of this sampling method and the performance results obtained with this prototype. The prototype consists of two multi-threshold discriminator boards and a time-to-digital converter (TDC) board. Each of the multi-threshold discriminator boards takes one input and provides up to eight threshold levels, which can be defined by users, for sampling the input signal. The TDC board employs the CERN HPTDC chip that determines the digitized times of the leading and falling edges of the discriminator output pulses. We connect our prototype electronics to the outputs of two Hamamatsu R9800 photomultiplier tubes (PMTs) that are individually coupled to a 6.25×6.25×25 mm3 LSO crystal. By analyzing waveform samples generated by using four thresholds, we obtain a coincidence timing resolution of about 340 ps and an ˜18% energy resolution at 511 keV. We are also able to estimate the decay-time constant from the resulting samples and obtain a mean value of 44 ns with an ˜9 ns FWHM. In comparison, using digitized waveforms obtained at a 20 GSps sampling rate for the same LSO/PMT modules we obtain ˜300 ps coincidence timing resolution, ˜14% energy resolution at 511 keV, and ˜5 ns FWHM for the estimated decay-time constant. Details of the results on the timing and energy resolutions by using the multi-threshold method indicate that it is a promising approach for implementing digital PET data acquisition.

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 01: On the use of proton radiography to reduce beam range uncertainties and improve patient positioning accuracy in proton therapy

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

Collins-Fekete, Charles-Antoine; Beaulieu, Luc; Se

2016-08-15

To present two related developments of proton radiography (pRad) to minimize range uncertainty in proton therapy. The first combines a pRad with an X-ray CT to produce a patient-specific relative stopping power (RSP) map. The second aims to improve the pRad spatial resolution for accurate registration prior to the first. The enhanced-pRad can also be used in a novel proton-CT reconstruction algorithm. Monte Carlo pRad were computed from three phantoms; the Gammex, the Catphan and an anthropomorphic head. An optimized cubic-spline estimator derives the most likely path. The length crossed by the protons voxel-by-voxel was calculated by combining their estimatedmore » paths with the CT. The difference between the theoretical (length×RSP) and measured energy loss was minimized through a least squares optimization (LSO) algorithm yielding the RSP map. To increase pRad spatial resolution for registration with the CT, the phantom was discretized into voxels columns. The average column RSP was optimized to maximize the proton energy loss likelihood (MLE). Simulations showed precise RSP (<0.75%) for Gammex materials except low-density lung (<1.2%). For the head, accurate RSP were obtained (µ=−0.10%1.5σ=1.12%) and the range precision was improved (ΔR80 of −0.20±0.35%). Spatial resolution was increased in pRad (2.75 to 6.71 lp/cm) and pCT from MLE-enhanced pRad (2.83 to 5.86 lp/cm). The LSO decreases the range uncertainty (R80σ<1.0%) while the MLE-enhanced pRad spatial resolution (+244%) and is a great candidate for pCT reconstruction.« less

Time-over-threshold for pulse shape discrimination in a time-of-flight phoswich PET detector

PubMed Central

Chang, Chen-Ming; Cates, Joshua W.; Levin, Craig S.

2016-01-01

It is well known that a PET detector capable of measuring both photon time-of-flight (TOF) and depth-of-interaction (DOI) improves the image quality and accuracy. Phoswich designs have been realized in PET detectors to measure DOI for more than a decade. However, PET detectors based on phoswich designs put great demand on the readout circuits, which have to differentiate the pulse shape produced by different crystal layers. A simple pulse shape discrimination approach is required to realize the phoswich designs in a clinical PET scanner, which consists of thousands of scintillation crystal elements. In this work, we studied time-over-threshold (ToT) as a pulse shape parameter for DOI. The energy, timing and DOI performance were evaluated for a phoswich detector design comprising 3 mm × 3 mm × 10 mm LYSO:Ce crystal optically coupled to 3 mm × 3 mm × 10 mm calcium co-doped LSO:Ce,Ca(0.4%) crystal read out by a silicon photomultiplier (SiPM). A DOI accuracy of 97.2% has been achieved for photopeak events using the proposed time-over-threshold (ToT) processing. The energy resolution without correction for SiPM non-linearity was 9.7 ± 0.2% and 11.3 ± 0.2% FWHM at 511 keV for LYSO and LSO crystal layers, respectively. The coincidence time resolution for photopeak events ranges from 164.6 ps to 183.1 ps FWHM, depending on the layer combinations. The coincidence time resolution for inter-crystal scatter events ranges from 214.6 ps to 418.3 ps FWHM, depending on the energy windows applied. These results show great promises of using ToT for pulse shape discrimination in a TOF phoswich detector since a ToT measurement can be easily implemented in readout electronics. PMID:27991437

PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants

PubMed Central

Parodi, Katia; Paganetti, Harald; Cascio, Ethan; Flanz, Jacob B.; Bonab, Ali A.; Alpert, Nathaniel M.; Lohmann, Kevin; Bortfeld, Thomas

2008-01-01

The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of the detector itself. In addition to PET alone, PET/CT imaging provides accurate information on the position of the imaged object and may assess possible anatomical changes during fractionated radiotherapy in clinical applications. PMID:17388158

Colocalization of vesicular glutamate transporters in the rat superior olivary complex.

PubMed

Billups, Brian

Vesicular glutamate transporters (VGLUTs) are responsible for the accumulation of the excitatory neurotransmitter glutamate into synaptic vesicles. It is currently controversial whether the two isoforms found in glutamatergic neurons, VGLUT1 and VGLUT2, are present at the same synapse or have entirely complementary patterns of distribution. Using fluorescent immunohistochemistry, this study examines the colocalization of these two transporters in the rat superior olivary complex (SOC) between postnatal day (P) 5 and 29. The medial and lateral superior olives (MSO; LSO) stain for both VGLUT1 and VGLUT2 at all ages studied, with VGLUT1 levels doubling over this developmental period and VGLUT2 levels remaining unchanged. The ventral nucleus of the trapezoid body (VNTB) strongly labels only for VGLUT2, despite the fact that glutamatergic synapses are present that are formed from collaterals of axons that go on to form synapses containing both VGLUT1 and VGLUT2. Principal neurons of the medial nucleus of the trapezoid body (MNTB) are surrounded by the calyx of Held presynaptic terminal, which is large enough to allow examination of VGLUT localization within a synapse. Throughout its postnatal developmental period a single calyx synapse contains both VGLUT1 and VGLUT2. Whereas VGLUT1 levels are greatly up-regulated from P5 to P29, VGLUT2 levels remain high. As the abundance of VGLUT determines the quantal size, this up-regulation will increase excitatory postsynaptic currents (EPSCs) and have influences on synaptic physiology.

Optimization and performance evaluation of the microPET II scanner for in vivo small-animal imaging

NASA Astrophysics Data System (ADS)

Yang, Yongfeng; Tai, Yuan-Chuan; Siegel, Stefan; Newport, Danny F.; Bai, Bing; Li, Quanzheng; Leahy, Richard M.; Cherry, Simon R.

2004-06-01

MicroPET II is a newly developed PET (positron emission tomography) scanner designed for high-resolution imaging of small animals. It consists of 17 640 LSO crystals each measuring 0.975 × 0.975 × 12.5 mm3, which are arranged in 42 contiguous rings, with 420 crystals per ring. The scanner has an axial field of view (FOV) of 4.9 cm and a transaxial FOV of 8.5 cm. The purpose of this study was to carefully evaluate the performance of the system and to optimize settings for in vivo mouse and rat imaging studies. The volumetric image resolution was found to depend strongly on the reconstruction algorithm employed and averaged 1.1 mm (1.4 µl) across the central 3 cm of the transaxial FOV when using a statistical reconstruction algorithm with accurate system modelling. The sensitivity, scatter fraction and noise-equivalent count (NEC) rate for mouse- and rat-sized phantoms were measured for different energy and timing windows. Mouse imaging was optimized with a wide open energy window (150-750 keV) and a 10 ns timing window, leading to a sensitivity of 3.3% at the centre of the FOV and a peak NEC rate of 235 000 cps for a total activity of 80 MBq (2.2 mCi) in the phantom. Rat imaging, due to the higher scatter fraction, and the activity that lies outside of the field of view, achieved a maximum NEC rate of 24 600 cps for a total activity of 80 MBq (2.2 mCi) in the phantom, with an energy window of 250-750 keV and a 6 ns timing window. The sensitivity at the centre of the FOV for these settings is 2.1%. This work demonstrates that different scanner settings are necessary to optimize the NEC count rate for different-sized animals and different injected doses. Finally, phantom and in vivo animal studies are presented to demonstrate the capabilities of microPET II for small-animal imaging studies.

A high resolution prototype small-animal PET scanner dedicated to mouse brain imaging

PubMed Central

Yang, Yongfeng; Bec, Julien; Zhou, Jian; Zhang, Mengxi; Judenhofer, Martin S; Bai, Xiaowei; Di, Kun; Wu, Yibao; Rodriguez, Mercedes; Dokhale, Purushottam; Shah, Kanai S.; Farrell, Richard; Qi, Jinyi; Cherry, Simon R.

2017-01-01

A prototype small-animal PET scanner was developed based on depth-encoding detectors using dual-ended readout of very small scintillator elements to produce high and uniform spatial resolution suitable for imaging the mouse brain. Methods The scanner consists of 16 tapered dual-ended readout detectors arranged in a ring of diameter 61 mm. The axial field of view is 7 mm and the transaxial field of view is 30 mm. The scintillator arrays consist of 14×14 lutetium oxyorthosilicate (LSO) elements, with a crystal size of 0.43×0.43 mm2 at the front end and 0.80×0.43 mm2 at the back end, and the crystal elements are 13 mm long. The arrays are read out by 8×8 mm2 and a 13×8 mm2 position-sensitive avalanche photodiodes (PSAPDs) placed at opposite ends of the array. Standard nuclear instrumentation module (NIM) electronics and a custom designed multiplexer are used for signal processing. Results The detector performance was measured and all except the very edge crystals could be clearly resolved. The average detector intrinsic spatial resolution in the axial direction was 0.61 mm. A depth of interaction resolution of 1.7 mm was achieved. The sensitivity of the scanner at center of the field of view was 1.02% for a lower energy threshold of 150 keV and 0.68% for a lower energy threshold of 250 keV. The spatial resolution within a field of view that can accommodate the entire mouse brain was ~0.6 mm using a 3D Maximum Likelihood-Expectation Maximization (ML-EM) reconstruction algorithm. Images of a micro hot-rod phantom showed that rods with diameter down to 0.5 mm could be resolved. First in vivo studies were obtained using 18F-fluoride and confirmed that 0.6 mm resolution can be achieved in the mouse head in vivo. Brain imaging studies with 18F-fluorodeoxyglucose were also acquired. Conclusion A prototype PET scanner achieving a spatial resolution approaching the physical limits for a small-bore PET scanner set by positron range and acolinearity was developed. Future plans are to add more detector rings to extend the axial field of view of the scanner and increase sensitivity. PMID:27013696

Characterization of Large-Area SiPM Array for PET Applications

NASA Astrophysics Data System (ADS)

Du, Junwei; Yang, Yongfeng; Bai, Xiaowei; Judenhofer, Martin S.; Berg, Eric; Di, Kun; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

2016-02-01

The performance of an 8 ×8 array of 6.0 ×6.0 mm2 (active area) SiPMs was evaluated for PET applications using crystal arrays with different pitch sizes (3.4, 1.5, 1.35, and 1.2 mm) and custom designed five-channel front-end readout electronics (four channels for position information and one channel for timing information). The total area of this SiPM array is 57.4 ×57.4 mm2, and the pitch size is 7.2 mm. It was fabricated using enhanced blue sensitivity SiPMs (MicroFB-60035-SMT) with peak spectral sensitivity at 420 nm. The performance of the SiPM array was characterized by measuring flood histogram decoding quality, energy resolution, timing resolution and saturation at several bias voltages (from 25.0 to 30.0 V in 0.5 V intervals) and two different temperatures ( 5° C and 20°C). Results show that the best flood histogram was obtained at a bias voltage of 28.0 V and 5°C and an array of polished LSO crystals with a pitch as small as 1.2 mm can be resolved. No saturation was observed up to a bias voltage of 29.5 V during the experiments, due to adequate light sharing between SiPMs. Energy resolution and timing resolution at 5°C ranged from 12.7 ±0.8% to 14.6 ±1.4% and 1.58 ±0.13 ns to 2.50 ±0.44 ns, for crystal array pitch sizes of 3.4 and 1.2 mm, respectively. Superior flood histogram quality, energy resolution and timing resolution were obtained with larger crystal array pitch sizes and at lower temperature. Based on our findings, we conclude that this large-area SiPM array can serve as a suitable photodetector for high-resolution small-animal PET or dedicated human brain PET scanners.

Whole slide images and digital media in pathology education, testing, and practice: the Oklahoma experience.

PubMed

Fung, Kar-Ming; Hassell, Lewis A; Talbert, Michael L; Wiechmann, Allan F; Chaser, Brad E; Ramey, Joel

2012-01-01

Examination of glass slides is of paramount importance in pathology training. Until the introduction of digitized whole slide images that could be accessed through computer networks, the sharing of pathology slides was a major logistic issue in pathology education and practice. With the help of whole slide images, our department has developed several online pathology education websites. Based on a modular architecture, this program provides online access to whole slide images, still images, case studies, quizzes and didactic text at different levels. Together with traditional lectures and hands-on experiences, it forms the back bone of our histology and pathology education system for residents and medical students. The use of digitized whole slide images has a.lso greatly improved the communication between clinicians and pathologist in our institute.

Linseed oil and DGAT1 K232A polymorphism: Effects on methane emission, energy and nitrogen metabolism, lactation performance, ruminal fermentation, and rumen microbial composition of Holstein-Friesian cows.

PubMed

van Gastelen, S; Visker, M H P W; Edwards, J E; Antunes-Fernandes, E C; Hettinga, K A; Alferink, S J J; Hendriks, W H; Bovenhuis, H; Smidt, H; Dijkstra, J

2017-11-01

Complex interactions between rumen microbiota, cow genetics, and diet composition may exist. Therefore, the effect of linseed oil, DGAT1 K232A polymorphism (DGAT1), and the interaction between linseed oil and DGAT1 on CH 4 and H 2 emission, energy and N metabolism, lactation performance, ruminal fermentation, and rumen bacterial and archaeal composition was investigated. Twenty-four lactating Holstein-Friesian cows (i.e., 12 with DGAT1 KK genotype and 12 with DGAT1 AA genotype) were fed 2 diets in a crossover design: a control diet and a linseed oil diet (LSO) with a difference of 22 g/kg of dry matter (DM) in fat content between the 2 diets. Both diets consisted of 40% corn silage, 30% grass silage, and 30% concentrates (DM basis). Apparent digestibility, lactation performance, N and energy balance, and CH 4 emission were measured in climate respiration chambers, and rumen fluid samples were collected using the oral stomach tube technique. No linseed oil by DGAT1 interactions were observed for digestibility, milk production and composition, energy and N balance, CH 4 and H 2 emissions, and rumen volatile fatty acid concentrations. The DGAT1 KK genotype was associated with a lower proportion of polyunsaturated fatty acids in milk fat, and with a higher milk fat and protein content, and proportion of saturated fatty acids in milk fat compared with the DGAT1 AA genotype, whereas the fat- and protein-corrected milk yield was unaffected by DGAT1. Also, DGAT1 did not affect nutrient digestibility, CH 4 or H 2 emission, ruminal fermentation or ruminal archaeal and bacterial concentrations. Rumen bacterial and archaeal composition was also unaffected in terms of the whole community, whereas at the genus level the relative abundances of some bacterial genera were found to be affected by DGAT1. The DGAT1 KK genotype was associated with a lower metabolizability (i.e., ratio of metabolizable to gross energy intake), and with a tendency for a lower milk N efficiency compared with the DGAT1 AA genotype. The LSO diet tended to decrease CH 4 production (g/d) by 8%, and significantly decreased CH 4 yield (g/kg of DM intake) by 6% and CH 4 intensity (g/kg of fat- and protein-corrected milk) by 11%, but did not affect H 2 emission. The LSO diet also decreased ruminal acetate molar proportion, the acetate to propionate ratio, and the archaea to bacteria ratio, whereas ruminal propionate molar proportion and milk N efficiency increased. Ruminal bacterial and archaeal composition tended to be affected by diet in terms of the whole community, with several bacterial genera found to be significantly affected by diet. These results indicate that DGAT1 does not affect enteric CH 4 emission and production pathways, but that it does affect traits other than lactation characteristics, including metabolizability, N efficiency, and the relative abundance of Bifidobacterium. Additionally, linseed oil reduces CH 4 emission independent of DGAT1 and affects the rumen microbiota and its fermentative activity. The Authors. Published by the Federation of Animal Science Societies and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Laser pixelation of thick scintillators for medical imaging applications: x-ray studies

NASA Astrophysics Data System (ADS)

Sabet, Hamid; Kudrolli, Haris; Marton, Zsolt; Singh, Bipin; Nagarkar, Vivek V.

2013-09-01

To achieve high spatial resolution required in nuclear imaging, scintillation light spread has to be controlled. This has been traditionally achieved by introducing structures in the bulk of scintillation materials; typically by mechanical pixelation of scintillators and fill the resultant inter-pixel gaps by reflecting materials. Mechanical pixelation however, is accompanied by various cost and complexity issues especially for hard, brittle and hygroscopic materials. For example LSO and LYSO, hard and brittle scintillators of interest to medical imaging community, are known to crack under thermal and mechanical stress; the material yield drops quickly with large arrays with high aspect ratio pixels and therefore the pixelation process cost increases. We are utilizing a novel technique named Laser Induced Optical Barriers (LIOB) for pixelation of scintillators that overcomes the issues associated with mechanical pixelation. In this technique, we can introduce optical barriers within the bulk of scintillator crystals to form pixelated arrays with small pixel size and large thickness. We applied LIOB to LYSO using a high-frequency solid-state laser. Arrays with different crystal thickness (5 to 20 mm thick), and pixel size (0.8×0.8 to 1.5×1.5 mm2) were fabricated and tested. The width of the optical barriers were controlled by fine-tuning key parameters such as lens focal spot size and laser energy density. Here we report on LIOB process, its optimization, and the optical crosstalk measurements using X-rays. There are many applications that can potentially benefit from LIOB including but not limited to clinical/pre-clinical PET and SPECT systems, and photon counting CT detectors.

Deletion of Fmr1 Alters Function and Synaptic Inputs in the Auditory Brainstem

PubMed Central

Rotschafer, Sarah E.; Marshak, Sonya; Cramer, Karina S.

2015-01-01

Fragile X Syndrome (FXS), a neurodevelopmental disorder, is the most prevalent single-gene cause of autism spectrum disorder. Autism has been associated with impaired auditory processing, abnormalities in the auditory brainstem response (ABR), and reduced cell number and size in the auditory brainstem nuclei. FXS is characterized by elevated cortical responses to sound stimuli, with some evidence for aberrant ABRs. Here, we assessed ABRs and auditory brainstem anatomy in Fmr1 -/- mice, an animal model of FXS. We found that Fmr1 -/- mice showed elevated response thresholds to both click and tone stimuli. Amplitudes of ABR responses were reduced in Fmr1 -/- mice for early peaks of the ABR. The growth of the peak I response with sound intensity was less steep in mutants that in wild type mice. In contrast, amplitudes and response growth in peaks IV and V did not differ between these groups. We did not observe differences in peak latencies or in interpeak latencies. Cell size was reduced in Fmr1 -/- mice in the ventral cochlear nucleus (VCN) and in the medial nucleus of the trapezoid body (MNTB). We quantified levels of inhibitory and excitatory synaptic inputs in these nuclei using markers for presynaptic proteins. We measured VGAT and VGLUT immunolabeling in VCN, MNTB, and the lateral superior olive (LSO). VGAT expression in MNTB was significantly greater in the Fmr1 -/- mouse than in wild type mice. Together, these observations demonstrate that FXS affects peripheral and central aspects of hearing and alters the balance of excitation and inhibition in the auditory brainstem. PMID:25679778

Initial tests of a prototype MRI-compatible PET imager

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan; Velan, S. Sendhil; Kross, Brain; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Wojcik, Randy

2006-12-01

Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI, will allow the correlation of form with function. Our group (a collaboration of West Virginia University and Jefferson Lab) is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode with an active FOV of 5×5×4 cm 3. Each MRI-PET detector module consists of an array of LSO detector elements (2.5×2.5×15 mm 3) coupled through a long fiber optic light guide to a single Hamamatsu flat panel PSPMT. The fiber optic light guide is made of a glued assembly of 2 mm diameter acrylic fibers with a total length of 2.5 m. The use of a light guides allows the PSPMTs to be positioned outside the bore of the 3 T General Electric MRI scanner used in the tests. Photon attenuation in the light guides resulted in an energy resolution of ˜60% FWHM, interaction of the magnetic field with PSPMT further reduced energy resolution to ˜85% FWHM. Despite this effect, excellent multi-plane PET and MRI images of a simple disk phantom were acquired simultaneously. Future work includes improved light guides, optimized magnetic shielding for the PSPMTs, construction of specialized coils to permit high-resolution MRI imaging, and use of the system to perform simultaneous PET and MRI or MR-spectroscopy .

Timing capabilities of garnet crystals for detection of high energy charged particles

NASA Astrophysics Data System (ADS)

Lucchini, M. T.; Gundacker, S.; Lecoq, P.; Benaglia, A.; Nikl, M.; Kamada, K.; Yoshikawa, A.; Auffray, E.

2017-04-01

Particle detectors at future collider experiments will operate at high collision rates and thus will have to face high pile up and a harsh radiation environment. Precision timing capabilities can help in the reconstruction of physics events by mitigating pile up effects. In this context, radiation tolerant, scintillating crystals coupled to silicon photomultipliers (SiPMs) can provide a flexible and compact option for the implementation of a precision timing layer inside large particle detectors. In this paper, we compare the timing performance of aluminum garnet crystals (YAG: Ce, LuAG: Ce, GAGG: Ce) and the improvements of their time resolution by means of codoping with Mg2+ ions. The crystals were read out using SiPMs from Hamamatsu glued to the rear end of the scintillator and their timing performance was evaluated by measuring the coincidence time resolution (CTR) of 150 GeV charged pions traversing a pair of crystals. The influence of crystal properties, such as density, light yield and decay kinetics on the timing performance is discussed. The best single detector time resolutions are in the range of 23-30 ps (sigma) and only achieved by codoping the garnet crystals with divalent ions, such as Mg2+. The much faster scintillation decay in the co-doped samples as compared to non co-doped garnets explains the higher timing performance. Samples of LSO: Ce, Ca and LYSO:Ce crystals have also been used as reference time device and showed a time resolution at the level of 17 ps, in agreement with previous results.

Low Volatile Organic Compound (VOC) Chemical Agent Resistant Coating (CARC)

DTIC Science & Technology

2000-04-01

hv1p 30 0 4 7 120 40 B15 +++--·····-+ 46168 36521 28 75 5 hv1p 30 0 2 3 75 80 Bl6 ++++++++++++ 46168 36521 28 120 30 conv 240 I 4 7 120 80 Low...Conventional· Bl2 28 HVLP Bl3 7 Conventional 1.4 1.2 2 Bl4 7 HVLP 1.1 2.3 4 BlS 28 HVLP B16 28 Conventional Notes: I. Only panel sets coated with...p p Bl4 572 574 3.0 4.0 4.0 3.5 p p BIS 274 243 4.0 4.0 4.0 4.5 p p Bl6 360 334 4.0 4.0 4.0 4.0 p p Experimental Set WR 7 days /lSO"C Oil

Whole Slide Images and Digital Media in Pathology Education, Testing, and Practice: The Oklahoma Experience

PubMed Central

Fung, Kar-Ming; Hassell, Lewis A.; Talbert, Michael L.; Wiechmann, Allan F.; Chaser, Brad E.; Ramey, Joel

2012-01-01

Examination of glass slides is of paramount importance in pathology training. Until the introduction of digitized whole slide images that could be accessed through computer networks, the sharing of pathology slides was a major logistic issue in pathology education and practice. With the help of whole slide images, our department has developed several online pathology education websites. Based on a modular architecture, this program provides online access to whole slide images, still images, case studies, quizzes and didactic text at different levels. Together with traditional lectures and hands-on experiences, it forms the back bone of our histology and pathology education system for residents and medical students. The use of digitized whole slide images has a.lso greatly improved the communication between clinicians and pathologist in our institute. PMID:21965282

A Review of Hydrazine Sensors: The State of the Art

NASA Technical Reports Server (NTRS)

Meneghelli, B. J.

2004-01-01

Several types of sensors have been developed over the past few years that quantify the vapor concentrations of the hydrazines. These sensor s are able to detect concentrations as low as 10 parts per billion (ppb) up to several parts per million (ppm). The scope of this review wi ll be focused on those sensors that are most current in the marketpla ce as either leak detectors or personnel monitors. Some technical information on the theory of operations of each hydrazine detector will a lso be included. The review will highlight current operations that utilize hydrazine sensors including the Kennedy Space Center (KSC), the United States Air Force (USAF) at Cape Canaveral Air Station (CCAS), USAF F-16 facilities. The orientation of the review will be towards giving users usable practical information on hydrazine sensors.

Garden cress (Lepidium sativum Linn.) seed oil as a potential feedstock for biodiesel production.

PubMed

Nehdi, Imededdine Arbi; Sbihi, Hassen; Tan, Chin Ping; Al-Resayes, Saud Ibrahim

2012-12-01

Lepidium sativum L. (garden cress) is a fast growing annual herb, native to Egypt and west Asia but widely cultivated in temperate climates throughout the world. L. sativum seed oil (LSO) extracted from plants grown in Tunisia was analyzed to determine whether it has potential as a raw material for biodiesel production. The oil content of the seeds was 26.77%, mainly composed of polyunsaturated (42.23%) and monounsaturated (39.62%) fatty acids. Methyl esters (LSOMEs) were prepared by base-catalyzed transesterification with a conversion rate of 96.8%. The kinematic viscosity (1.92 mm(2)/s), cetane number (49.23), gross heat value (40.45), and other fuel properties were within the limits for biodiesel specified by the ASTM (American Standard for Testing and Materials). This study showed that LSOMEs have the potential to supplement petroleum-based diesel. Copyright © 2012 Elsevier Ltd. All rights reserved.

Control of secondary instability of the crossflow and Görtler-like vortices (Success and problems)

NASA Astrophysics Data System (ADS)

Kozlov, Viktor V.; Grek, Genrich R.

The secondary instability on a group of crossflow vortices developing in a swept wing boundary layer is described. It is shown that, for travelling waves, there is a region of linear development, and the growth rate of disturbances appreciably depends on the separation between the vortices. Methods of controlling the secondary instability of the vortices by a controlled wave and local suction are proposed and substantiated. The stability of a flat plate boundary layer modulated by G&ou ml;rtler-like stationary vortices is described. Vortices were generated inside the boundary layer by means of roughness elements arranged in a regular array along the spanwise (z) direction. Transition is not caused directly by these structures, but by the growth of small amplitude travelling waves riding on top of the steady vortices. This situation is analogous to the transition process in Görtler and cross-flows. The waves were found to amplify up to a stage where higher harmonics are gener ated, leading to turbulent breakdown and disintegration of the spanwise boundary layer structure. For strong modulations, the observed instability is quite powerful, and can be excited "naturally" by small uncontrollable background disturbances. Controlled oscillations were then introduced by means of a vibrating ribbon, allowing a detailed investigation of the wave characteristics. The instability seems to be associated with the spanwise gradients of the mean flow, , and at all z-positions, the maximum wave amplitude was found at a wall-normal position where the mean velocity is equal to the phase velocity of the wave, U(y)=c, i.e., at the local critical layer. Unstable waves were observed at frequency well above those for which Tollmien-Schlichting (TS) waves amplify in the Blasius boundary layer. Excitation at lower frequencies and milder basic flow modulation showed that TS-type waves may a lso develop. Study of the transition control in that flow by means of riblets shows that the effect of the riblets is to suppress longitudinal vortex structures in a boundary layer. The boundary layer becomes stable with respect to high-frequency travelling waves, which cause the transition in the absence of the riblets.

Properties of transparent (Gd,Lu)3(Al,Ga)5O12:Ce ceramic with Mg, Ca and Ce co-dopants

NASA Astrophysics Data System (ADS)

Wang, Yimin; Baldoni, Gary; Brecher, Charles; Rhodes, William H.; Shirwadkar, Urmila; Glodo, Jarek; Shah, Ishaan; Ji, Chuncheng

2015-08-01

Cerium activated mixed lutetium/gadolinium- and aluminum/gallium-based garnets have great potential as host scintillators for medical imaging applications. (Gd,Lu)3(Al,Ga)5O12:Ce and denoted as GLuGAG feature high effective atomic number and good light yield, which make it particularly attractive for Positron Emission Tomography (PET) and other γ-ray detection applications. For PET application, rapid decay and good timing resolution are extremely important. Most Ce-doped mixed garnet materials such as GLuGAG:Ce, have their main decay component at around 80 ns. However, it has been reported that the decays of some single crystal scintillators (e.g., LSO and GGAG) can be effectively accelerated by codoping with selected additives such as Ca, Mg and B. In this study, transparent polycrystalline (Gd,Lu)3(Al,Ga)5O12:Ce ceramics codoped with Ca or Mg or additional Ce, were fabricated by the sinter-HIP approach. It was found the transmission of the ceramics are closely related to the microstructure of the ceramics. As the co-dopant levels increase, 2nd phase occurs in the ceramic and thus transparency of the ceramic decreases. Ca and Mg co-doping in GLuGAG:Ce ceramic effectively accelerate decays of GLuGAG:Ce ceramics at a cost of light output. However, additional Ce doping in the GLuGAG:Ce has no benefit on improving decay time but, on the other hand, reduces transmission, light output. The mechanism under the different scintillation behaviors with Mg, Ca and Ce dopants are discussed. The results suggest that decay time of GLuGAG:Ce ceramics can be effectively tailored by co-doping GLuGAG:Ce ceramic with Mg and Ca for applications with optimal timing resolution.

Comparative Performance in Single-Port Versus Multiport Minimally Invasive Surgery, and Small Versus Large Operative Working Spaces

PubMed Central

Marcus, Hani J.; Seneci, Carlo A.; Hughes-Hallett, Archie; Cundy, Thomas P.; Nandi, Dipankar; Yang, Guang-Zhong; Darzi, Ara

2015-01-01

Background. Surgical approaches such as transanal endoscopic microsurgery, which utilize small operative working spaces, and are necessarily single-port, are particularly demanding with standard instruments and have not been widely adopted. The aim of this study was to compare simultaneously surgical performance in single-port versus multiport approaches, and small versus large working spaces. Methods. Ten novice, 4 intermediate, and 1 expert surgeons were recruited from a university hospital. A preclinical randomized crossover study design was implemented, comparing performance under the following conditions: (1) multiport approach and large working space, (2) multiport approach and intermediate working space, (3) single-port approach and large working space, (4) single-port approach and intermediate working space, and (5) single-port approach and small working space. In each case, participants performed a peg transfer and pattern cutting tasks, and each task repetition was scored. Results. Intermediate and expert surgeons performed significantly better than novices in all conditions (P < .05). Performance in single-port surgery was significantly worse than multiport surgery (P < .01). In multiport surgery, there was a nonsignificant trend toward worsened performance in the intermediate versus large working space. In single-port surgery, there was a converse trend; performances in the intermediate and small working spaces were significantly better than in the large working space. Conclusions. Single-port approaches were significantly more technically challenging than multiport approaches, possibly reflecting loss of instrument triangulation. Surprisingly, in single-port approaches, in which triangulation was no longer a factor, performance in large working spaces was worse than in intermediate and small working spaces. PMID:26464468

Comparative Performance in Single-Port Versus Multiport Minimally Invasive Surgery, and Small Versus Large Operative Working Spaces: A Preclinical Randomized Crossover Trial.

PubMed

Marcus, Hani J; Seneci, Carlo A; Hughes-Hallett, Archie; Cundy, Thomas P; Nandi, Dipankar; Yang, Guang-Zhong; Darzi, Ara

2016-04-01

Surgical approaches such as transanal endoscopic microsurgery, which utilize small operative working spaces, and are necessarily single-port, are particularly demanding with standard instruments and have not been widely adopted. The aim of this study was to compare simultaneously surgical performance in single-port versus multiport approaches, and small versus large working spaces. Ten novice, 4 intermediate, and 1 expert surgeons were recruited from a university hospital. A preclinical randomized crossover study design was implemented, comparing performance under the following conditions: (1) multiport approach and large working space, (2) multiport approach and intermediate working space, (3) single-port approach and large working space, (4) single-port approach and intermediate working space, and (5) single-port approach and small working space. In each case, participants performed a peg transfer and pattern cutting tasks, and each task repetition was scored. Intermediate and expert surgeons performed significantly better than novices in all conditions (P < .05). Performance in single-port surgery was significantly worse than multiport surgery (P < .01). In multiport surgery, there was a nonsignificant trend toward worsened performance in the intermediate versus large working space. In single-port surgery, there was a converse trend; performances in the intermediate and small working spaces were significantly better than in the large working space. Single-port approaches were significantly more technically challenging than multiport approaches, possibly reflecting loss of instrument triangulation. Surprisingly, in single-port approaches, in which triangulation was no longer a factor, performance in large working spaces was worse than in intermediate and small working spaces. © The Author(s) 2015.

Actualizing Flexible National Security Space Systems

DTIC Science & Technology

2011-01-01

single launch vehicle is a decision unique to small satellites that adds an extra dimension to the launch risk calculation. While bundling...following a launch failure. The ability to bundle multiple payloads on a single launch vehicle is a decision unique to small satellites that adds an extra ... dimension to the launch risk calculation. While bundling multiple small satellites on a single launch vehicle spreads the initial launch cost across

A Single IGF1 Allele Is a Major Determinant of Small Size in Dogs

PubMed Central

Sutter, Nathan B.; Bustamante, Carlos D.; Chase, Kevin; Gray, Melissa M.; Zhao, Keyan; Zhu, Lan; Padhukasahasram, Badri; Karlins, Eric; Davis, Sean; Jones, Paul G.; Quignon, Pascale; Johnson, Gary S.; Parker, Heidi G.; Fretwell, Neale; Mosher, Dana S.; Lawler, Dennis F.; Satyaraj, Ebenezer; Nordborg, Magnus; Lark, K. Gordon; Wayne, Robert K.; Ostrander, Elaine A.

2009-01-01

The domestic dog exhibits greater diversity in body size than any other terrestrial vertebrate. We used a strategy that exploits the breed structure of dogs to investigate the genetic basis of size. First, through a genome-wide scan, we identified a major quantitative trait locus (QTL) on chromosome 15 influencing size variation within a single breed. Second, we examined genetic variation in the 15-megabase interval surrounding the QTL in small and giant breeds and found marked evidence for a selective sweep spanning a single gene (IGF1), encoding insulin-like growth factor 1. A single IGF1 single-nucleotide polymorphism haplotype is common to all small breeds and nearly absent from giant breeds, suggesting that the same causal sequence variant is a major contributor to body size in all small dogs. PMID:17412960

A single IGF1 allele is a major determinant of small size in dogs.

PubMed

Sutter, Nathan B; Bustamante, Carlos D; Chase, Kevin; Gray, Melissa M; Zhao, Keyan; Zhu, Lan; Padhukasahasram, Badri; Karlins, Eric; Davis, Sean; Jones, Paul G; Quignon, Pascale; Johnson, Gary S; Parker, Heidi G; Fretwell, Neale; Mosher, Dana S; Lawler, Dennis F; Satyaraj, Ebenezer; Nordborg, Magnus; Lark, K Gordon; Wayne, Robert K; Ostrander, Elaine A

2007-04-06

The domestic dog exhibits greater diversity in body size than any other terrestrial vertebrate. We used a strategy that exploits the breed structure of dogs to investigate the genetic basis of size. First, through a genome-wide scan, we identified a major quantitative trait locus (QTL) on chromosome 15 influencing size variation within a single breed. Second, we examined genetic variation in the 15-megabase interval surrounding the QTL in small and giant breeds and found marked evidence for a selective sweep spanning a single gene (IGF1), encoding insulin-like growth factor 1. A single IGF1 single-nucleotide polymorphism haplotype is common to all small breeds and nearly absent from giant breeds, suggesting that the same causal sequence variant is a major contributor to body size in all small dogs.

Evaluation of an MR-compatible blood sampler for PET

NASA Astrophysics Data System (ADS)

Breuer, J.; Grazioso, R.; Zhang, N.; Schmand, M.; Wienhard, K.

2010-10-01

The integration of magnetic resonance imaging (MRI) and positron emission tomography (PET) is an upcoming hybrid imaging technique. Prototype scanners for pre-clinical and clinical research have been built and tested. However, the potential of the PET part can be better exploited if the arterial input function (AIF) of the administered tracer is known. This work presents a dedicated MR-compatible blood sampling system for precise measurement of the AIF in an MR-PET study. The device basically consists of an LSO/APD-detector assembly which performs a coincidence measurement of the annihilation photons resulting from positron decays. During the measurement, arterial blood is drawn continuously from an artery and lead through the detector unit. Besides successful tests of the MR compatibility and the detector performance, measurements of the AIF of rats have been carried out. The results show that the developed blood sampling system is a practical and reliable tool for measuring the AIF in MR-PET studies.

The Road to the Common PET/CT Detector

NASA Astrophysics Data System (ADS)

Nassalski, Antoni; Moszynski, Marek; Szczesniak, Tomasz; Wolski, Dariusz; Batsch, Tadeusz

2007-10-01

Growing interest in the development of dual modality positron emission/X-rays tomography (PET/CT) systems prompts researchers to face a new challenge: to acquire both the anatomical and functional information in the same measurement, simultaneously using the same detection system and electronics. The aim of this work was to study a detector consisting of LaBr3, LSO or LYSO pixel crystals coupled to an avalanche photodiode (APD). The measurements covered tests of the detectors in PET and CT modes, respectively. The measurements included the determination of light output, energy resolution, the non-proportionality of the light yield and the time resolution for 511 keV annihilation quanta; analysis also included characterizing the PET detector, and determining the dependence of counting rate versus mean current of the APD in the X-ray detection. In the present experiment, the use of counting and current modes in the CT detection increases the dynamic range of the measured dose of X-rays by a factor of 20, compared to the counting mode alone.

Docosahexaenoic acid (DHA) at the sn-2 position of triacylglycerols increases DHA incorporation in brown, but not in white adipose tissue, of hamsters.

PubMed

Lopes, Paula A; Bandarra, Narcisa M; Martins, Susana V; Madeira, Marta S; Ferreira, Júlia; Guil-Guerrero, José L; Prates, José A M

2018-06-01

We hypothesised that the incorporation of docosahexaenoic acid (DHA) across adipose tissues will be higher when it is ingested as triacylglycerols (TAG) structured at the sn-2 position. Ten-week old male hamsters were allocated to 4 dietary treatments (n = 10): linseed oil (LSO-control group), fish oil (FO), fish oil ethyl esters (FO-EE) and structured DHA at the sn-2 position of TAG (DHA-SL) during 12 weeks. In opposition to the large variations found for fatty acid composition in retroperitoneal white adipose tissue (WAT), brown adipose tissue (BAT) was less responsive to diets. DHA was not found in subcutaneous and retroperitoneal WAT depots but it was successfully incorporated in BAT reaching the highest percentage in DHA-SL. The PCA on plasma hormones (insulin, leptin, adiponectin) and fatty acids discriminated BAT from WATs pointing towards an individual signature on fatty acid deposition, but did not allow for full discrimination of dietary treatments within each adipose tissue.

Simulation study of PET detector configuration with thick light guide and GAPD array having large-area microcells for high effective quantum efficiency.

PubMed

Kang, Jihoon; Choi, Yong

2016-07-01

Light sharing PET detector configuration coupled with thick light guide and Geiger-mode avalanche photodiode (GAPD) with large-area microcells was proposed to overcome the energy non-linearity problem and to obtain high light collection efficiency (LCE). A Monte-Carlo simulation was conducted for the three types of LSO block, 4 × 4 array of 3 × 3 × 20 mm(3) discrete crystals, 6 × 6 array of 2 × 2 × 20 mm(3) discrete crystals, and 12 × 12 array of 1 × 1 × 20 mm(3) discrete crystals, to investigate the scintillation light distribution after conversion of the γ-rays in LSO. The incident photons were read out by three types of 4 × 4 array photosensors, which were PSPMT of 25% quantum efficiency (QE), GAPD1 with 50 × 50 µm(2) microcells of 30% photon detection efficiency (PDE) and GAPD2 with 100 × 100 µm(2) of 45% PDE. The number of counted photons in each photosensor was analytically calculated. The LCE, linearity and flood histogram were examined for each PET detector module having 99 different configurations as a function of light guide thickness ranging from 0 to 10 mm. The performance of PET detector modules based on GAPDs was considerably improved by using the thick light guide. The LCE was increased from 24 to 30% and from 14 to 41%, and the linearity was also improved from 0.97 to 0.99 and from 0.75 to 0.99, for GAPD1 and GAPD2, respectively. As expected, the performance of PSPMT based detector did not change. The flood histogram of 12 × 12 array PET detector modules using 3 mm light guide coupled with GAPDs was obtained by simulation, and all crystals of 1 × 1 × 20 mm(3) size were clearly identified. PET detector module coupled with thick light guide and GAPD array with large-area microcells was proposed to obtain high QE and high spatial resolution, and its feasibility was verified. This study demonstrated that the overall PET performance of the proposed design was considerably improved, and this approach will provide opportunities to develop GAPD based PET detector with a high LCE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Small fibre neuropathy in mitochondrial diseases explored with sudoscan.

PubMed

Luigetti, Marco; Primiano, Guido; Cuccagna, Cristina; Bernardo, Daniela; Sauchelli, Donato; Vollono, Catello; Servidei, Serenella

2018-06-01

Polyneuropathy in mitochondrial diseases (MDs) is relatively common and widely investigated, but few data are instead reported about small fibres involvement. In order to investigate the involvement of small fibres in MDs we performed extensive neurophysiological test (nerve conduction studies; sympathetic skin response; sudoscan) in 27 patients with genetic diagnosis of MD (7 m.3243A > G; 4 m.8344A > G; 9 single mtDNA deletion; 7 multiple mtDNA deletions). NCS showed a polyneuropathy in 11/27 cases (41%). The incidence was very high in POLG1 (100%), m.8344A > G (75%) and m.3243A > G (43%), while only 11% of patients with single deletion had evidence of large fibres involvement. Sympathetic skin response was abnormal only in three patients (one progressive external ophthalmoplegia with single mtDNA deletion; one patient with m.3243A > G mutation; one patient with POLG1 mutation). Sudoscan revealed the presence of an autonomic small fibres dysfunction in 9/27 cases (33%), most of them (7/9) carrying a single mtDNA deletion. Sudoscan data were also confirmed in a sub-group of patients by laser evoked potentials study. Considering only patients with single mtDNA deletion 7/9 (78%) showed abnormal results at sudoscan. Small fibre neuropathy is another feature to investigate in mitochondrial diseases and seems specifically associated with the presence of single mtDNA deletion. The correct identification through specific neurophysiological tests of small fibres involvement in MDs represents another tile in this challenging diagnosis. Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Anti-Brownian ELectrokinetic (ABEL) Trapping of Single High Density Lipoprotein (HDL) Particles

NASA Astrophysics Data System (ADS)

Bockenhauer, Samuel; Furstenberg, Alexandre; Wang, Quan; Devree, Brian; Jie Yao, Xiao; Bokoch, Michael; Kobilka, Brian; Sunahara, Roger; Moerner, W. E.

2010-03-01

The ABEL trap is a novel device for trapping single biomolecules in solution for extended observation. The trap estimates the position of a fluorescently-labeled object as small as ˜10 nm in solution and then applies a feedback electrokinetic drift every 20 us to trap the object by canceling its Brownian motion. We use the ABEL trap to study HDL particles at the single-copy level. HDL particles, essential in regulation of ``good'' cholesterol in humans, comprise a small (˜10 nm) lipid bilayer disc bounded by a belt of apolipoproteins. By engineering HDL particles with single fluorescent donor/acceptor probes and varying lipid compositions, we are working to study lipid diffusion on small length scales. We also use HDL particles as hosts for single transmembrane receptors, which should enable study of receptor conformational dynamics on long timescales.

SU-C-201-01: Investigation of the Effects of Scintillator Surface Treatment On Light Output Measurements with SiPM Detectors

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

Valenciaga, Y; Prout, D; Chatziioannou, A

2015-06-15

Purpose: To examine the effect of different scintillator surface treatments (BGO crystals) on the fraction of scintillation photons that exit the crystal and reach the photodetector (SiPM). Methods: Positron Emission Tomography is based on the detection of light that exits scintillator crystals, after annihilation photons deposit energy inside these crystals. A considerable fraction of the scintillation light gets trapped or absorbed after going through multiple internal reflections on the interfaces surrounding the crystals. BGO scintillator crystals generate considerably less scintillation light than crystals made of LSO and its variants. Therefore, it is crucial that the small amount of light producedmore » by BGO exits towards the light detector. The surface treatment of scintillator crystals is among the factors affecting the ability of scintillation light to reach the detectors. In this study, we analyze the effect of different crystal surface treatments on the fraction of scintillation light that is detected by the solid state photodetector (SiPM), once energy is deposited inside a BGO crystal. Simulations were performed by a Monte Carlo based software named GATE, and validated by measurements from individual BGO crystals coupled to Philips digital-SiPM sensor (DPC-3200). Results: The results showed an increment in light collection of about 4 percent when only the exit face of the BGO crystal, is unpolished; compared to when all the faces are polished. However, leaving several faces unpolished caused a reduction of at least 10 percent of light output when the interaction occurs as far from the exit face of the crystal as possible compared to when it occurs very close to the exit face. Conclusion: This work demonstrates the advantages on light collection from leaving unpolished the exit face of BGO crystals. The configuration with best light output will be used to obtain flood images from BGO crystal arrays coupled to SiPM sensors.« less

Fusion splicing small-core photonic crystal fibers and single-mode fibers by repeated arc discharges.

PubMed

Xiao, Limin; Jin, Wei; Demokan, M S

2007-01-15

We demonstrate a novel method for low-loss splicing small-core photonic crystal fibers (PCFs) and single-mode fibers (SMFs) by repeated arc discharges using a conventional fusion splicer. An optimum mode field match at the interface of PCF-SMF and an adiabatic mode field variation in the longitudinal direction of the small-core PCF can be achieved by repeated arc discharges applied over the splicing joint to gradually collapse the air holes of the small-core PCF. This method is simple and offers a practical solution for light coupling between small-core PCFs and SMFs.

Fusion splicing small-core photonic crystal fibers and single-mode fibers by repeated arc discharges

NASA Astrophysics Data System (ADS)

Xiao, Limin; Jin, Wei; Demokan, M. S.

2007-01-01

We demonstrate a novel method for low-loss splicing small-core photonic crystal fibers (PCFs) and single-mode fibers (SMFs) by repeated arc discharges using a conventional fusion splicer. An optimum mode field match at the interface of PCF-SMF and an adiabatic mode field variation in the longitudinal direction of the small-core PCF can be achieved by repeated arc discharges applied over the splicing joint to gradually collapse the air holes of the small-core PCF. This method is simple and offers a practical solution for light coupling between small-core PCFs and SMFs.

Lesion detection and quantification performance of the Tachyon-I time-of-flight PET scanner: phantom and human studies.

PubMed

Zhang, Xuezhu; Peng, Qiyu; Zhou, Jian; Huber, Jennifer S; Moses, William W; Qi, Jinyi

2018-03-16

The first generation Tachyon PET (Tachyon-I) is a demonstration single-ring PET scanner that reaches a coincidence timing resolution of 314 ps using LSO scintillator crystals coupled to conventional photomultiplier tubes. The objective of this study was to quantify the improvement in both lesion detection and quantification performance resulting from the improved time-of-flight (TOF) capability of the Tachyon-I scanner. We developed a quantitative TOF image reconstruction method for the Tachyon-I and evaluated its TOF gain for lesion detection and quantification. Scans of either a standard NEMA torso phantom or healthy volunteers were used as the normal background data. Separately scanned point source and sphere data were superimposed onto the phantom or human data after accounting for the object attenuation. We used the bootstrap method to generate multiple independent noisy datasets with and without a lesion present. The signal-to-noise ratio (SNR) of a channelized hotelling observer (CHO) was calculated for each lesion size and location combination to evaluate the lesion detection performance. The bias versus standard deviation trade-off of each lesion uptake was also calculated to evaluate the quantification performance. The resulting CHO-SNR measurements showed improved performance in lesion detection with better timing resolution. The detection performance was also dependent on the lesion size and location, in addition to the background object size and shape. The results of bias versus noise trade-off showed that the noise (standard deviation) reduction ratio was about 1.1-1.3 over the TOF 500 ps and 1.5-1.9 over the non-TOF modes, similar to the SNR gains for lesion detection. In conclusion, this Tachyon-I PET study demonstrated the benefit of improved time-of-flight capability on lesion detection and ROI quantification for both phantom and human subjects.

A GATE evaluation of the sources of error in quantitative {sup 90}Y PET

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

Strydhorst, Jared, E-mail: jared.strydhorst@gmail.

Purpose: Accurate reconstruction of the dose delivered by {sup 90}Y microspheres using a postembolization PET scan would permit the establishment of more accurate dose–response relationships for treatment of hepatocellular carcinoma with {sup 90}Y. However, the quality of the PET data obtained is compromised by several factors, including poor count statistics and a very high random fraction. This work uses Monte Carlo simulations to investigate what impact factors other than low count statistics have on the quantification of {sup 90}Y PET. Methods: PET acquisitions of two phantoms—a NEMA PET phantom and the NEMA IEC PET body phantom-containing either {sup 90}Y ormore » {sup 18}F were simulated using GATE. Simulated projections were created with subsets of the simulation data allowing the contributions of random, scatter, and LSO background to be independently evaluated. The simulated projections were reconstructed using the commercial software for the simulated scanner, and the quantitative accuracy of the reconstruction and the contrast recovery of the reconstructed images were evaluated. Results: The quantitative accuracy of the {sup 90}Y reconstructions were not strongly influenced by the high random fraction present in the projection data, and the activity concentration was recovered to within 5% of the known value. The contrast recovery measured for simulated {sup 90}Y data was slightly poorer than that for simulated {sup 18}F data with similar count statistics. However, the degradation was not strongly linked to any particular factor. Using a more restricted energy range to reduce the random fraction in the projections had no significant effect. Conclusions: Simulations of {sup 90}Y PET confirm that quantitative {sup 90}Y is achievable with the same approach as that used for {sup 18}F, and that there is likely very little margin for improvement by attempting to model aspects unique to {sup 90}Y, such as the much higher random fraction or the presence of bremsstrahlung in the singles data.« less

Lesion detection and quantification performance of the Tachyon-I time-of-flight PET scanner: phantom and human studies

NASA Astrophysics Data System (ADS)

Zhang, Xuezhu; Peng, Qiyu; Zhou, Jian; Huber, Jennifer S.; Moses, William W.; Qi, Jinyi

2018-03-01

The first generation Tachyon PET (Tachyon-I) is a demonstration single-ring PET scanner that reaches a coincidence timing resolution of 314 ps using LSO scintillator crystals coupled to conventional photomultiplier tubes. The objective of this study was to quantify the improvement in both lesion detection and quantification performance resulting from the improved time-of-flight (TOF) capability of the Tachyon-I scanner. We developed a quantitative TOF image reconstruction method for the Tachyon-I and evaluated its TOF gain for lesion detection and quantification. Scans of either a standard NEMA torso phantom or healthy volunteers were used as the normal background data. Separately scanned point source and sphere data were superimposed onto the phantom or human data after accounting for the object attenuation. We used the bootstrap method to generate multiple independent noisy datasets with and without a lesion present. The signal-to-noise ratio (SNR) of a channelized hotelling observer (CHO) was calculated for each lesion size and location combination to evaluate the lesion detection performance. The bias versus standard deviation trade-off of each lesion uptake was also calculated to evaluate the quantification performance. The resulting CHO-SNR measurements showed improved performance in lesion detection with better timing resolution. The detection performance was also dependent on the lesion size and location, in addition to the background object size and shape. The results of bias versus noise trade-off showed that the noise (standard deviation) reduction ratio was about 1.1–1.3 over the TOF 500 ps and 1.5–1.9 over the non-TOF modes, similar to the SNR gains for lesion detection. In conclusion, this Tachyon-I PET study demonstrated the benefit of improved time-of-flight capability on lesion detection and ROI quantification for both phantom and human subjects.

Reduction of spontaneous somatic mutation frequency by a low-dose X irradiation of Drosophila larvae and possible involvement of DNA single-strand damage repair.

PubMed

Koana, Takao; Takahashi, Takashi; Tsujimura, Hidenobu

2012-03-01

The third instar larvae of Drosophila were irradiated with X rays, and the somatic mutation frequency in their wings was measured after their eclosion. In the flies with normal DNA repair and apoptosis functions, 0.2 Gy irradiation at 0.05 Gy/min reduced the frequency of the so-called small spot (mutant cell clone with reduced reproductive activity) compared with that in the sham-irradiated flies. When apoptosis was suppressed using the baculovirus p35 gene, the small spot frequency increased four times in the sham-irradiated control group, but the reduction by the 0.2-Gy irradiation was still evident. In a non-homologous end joining-deficient mutant, the small spot frequency was also reduced by 0.2 Gy radiation. In a mutant deficient in single-strand break repair, no reduction in the small spot frequency by 0.2 Gy radiation was observed, and the small spot frequency increased with the radiation dose. Large spot (mutant cell clone with normal reproductive activity) frequency was not affected by suppression of apoptosis and increased monotonically with radiation dose in wild-type larvae and in mutants for single- or double-strand break repair. It is hypothesized that some of the small spots resulted from single-strand damage and, in wild-type larvae, 0.2 Gy radiation activated the normal single-strand break repair gene, which reduced the background somatic mutation frequency.

Pulsed Direct Current Electrospray: Enabling Systematic Analysis of Small Volume Sample by Boosting Sample Economy.

PubMed

Wei, Zhenwei; Xiong, Xingchuang; Guo, Chengan; Si, Xingyu; Zhao, Yaoyao; He, Muyi; Yang, Chengdui; Xu, Wei; Tang, Fei; Fang, Xiang; Zhang, Sichun; Zhang, Xinrong

2015-11-17

We had developed pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) for systematically profiling and determining components in small volume sample. Pulsed-dc-ESI utilized constant high voltage to induce the generation of single polarity pulsed electrospray remotely. This method had significantly boosted the sample economy, so as to obtain several minutes MS signal duration from merely picoliter volume sample. The elongated MS signal duration enable us to collect abundant MS(2) information on interested components in a small volume sample for systematical analysis. This method had been successfully applied for single cell metabolomics analysis. We had obtained 2-D profile of metabolites (including exact mass and MS(2) data) from single plant and mammalian cell, concerning 1034 components and 656 components for Allium cepa and HeLa cells, respectively. Further identification had found 162 compounds and 28 different modification groups of 141 saccharides in a single Allium cepa cell, indicating pulsed-dc-ESI a powerful tool for small volume sample systematical analysis.

Small file aggregation in a parallel computing system

DOEpatents

Faibish, Sorin; Bent, John M.; Tzelnic, Percy; Grider, Gary; Zhang, Jingwang

2014-09-02

Techniques are provided for small file aggregation in a parallel computing system. An exemplary method for storing a plurality of files generated by a plurality of processes in a parallel computing system comprises aggregating the plurality of files into a single aggregated file; and generating metadata for the single aggregated file. The metadata comprises an offset and a length of each of the plurality of files in the single aggregated file. The metadata can be used to unpack one or more of the files from the single aggregated file.

Three-terminal graphene single-electron transistor fabricated using feedback-controlled electroburning

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

Puczkarski, Paweł; Gehring, Pascal, E-mail: pascal.gehring@materials.ox.ac.uk; Lau, Chit S.

2015-09-28

We report room-temperature Coulomb blockade in a single layer graphene three-terminal single-electron transistor fabricated using feedback-controlled electroburning. The small separation between the side gate electrode and the graphene quantum dot results in a gate coupling up to 3 times larger compared to the value found for the back gate electrode. This allows for an effective tuning between the conductive and Coulomb blocked state using a small side gate voltage of about 1 V. The technique can potentially be used in the future to fabricate all-graphene based room temperature single-electron transistors or three terminal single molecule transistors with enhanced gate coupling.

Investigating the Catalytic Growth of Carbon Nanotubes with In Situ Raman Monitoring

DTIC Science & Technology

2015-06-01

single-walled carbon nanotube growth using cobalt deposited on Si/SiO2 as a model system. In situ Raman studies revealed that thin catalyst layers... cobalt thickness were studied. Surface analyses showed that during the catalyst preparation, catalyst atoms at the interface with silica form small...nanostructures. However, highly-reducing conditions are required to reduce the small silicate domains into small cobalt particles able to grow single-walled

Effect of dietary starch concentration and fish oil supplementation on milk yield and composition, diet digestibility, and methane emissions in lactating dairy cows.

PubMed

Pirondini, M; Colombini, S; Mele, M; Malagutti, L; Rapetti, L; Galassi, G; Crovetto, G M

2015-01-01

The aim of this study was to evaluate the effects of diets with different starch concentrations and fish oil (FO) supplementation on lactation performance, in vivo total-tract nutrient digestibility, N balance, and methane (CH4) emissions in lactating dairy cows. The experiment was conducted as a 4×4 Latin square design with a 2×2 factorial arrangement: 2 concentrations of dietary starch [low vs. high: 23.7 and 27.7% on a dry matter (DM) basis; neutral detergent fiber/starch ratios: 1.47 and 1.12], the presence or absence of FO supplement (0.80% on a DM basis), and their interaction were evaluated. Four Italian Friesian cows were fed 1 of the following 4 diets in 4 consecutive 26-d periods: (1) low starch (LS), (2) low starch plus FO (LSO), (3) high starch (HS), and (4) high starch plus FO (HSO). The diets contained the same amount of forages (corn silage, alfalfa and meadow hays). The starch concentration was balanced using different proportions of corn meal and soybean hulls. The cows were housed in metabolic stalls inside open-circuit respiration chambers to allow measurement of CH4 emission and the collection of separate urine and feces. No differences among treatments were observed for DM intake. We observed a trend for FO to increase milk yield: 29.2 and 27.5kg/d, on average, for diets with and without FO, respectively. Milk fat was affected by the interaction between dietary starch and FO: milk fat decreased only in the HSO diet. Energy-corrected milk (ECM) was affected by the interaction between starch and FO, with a positive effect of FO on the LS diet. Fish oil supplementation decreased the n-6:n-3 ratio of milk polyunsaturated fatty acids. High-starch diets negatively influenced all digestibility parameters measured except starch, whereas FO improved neutral detergent fiber digestibility (41.9 vs. 46.1% for diets without and with FO, respectively, and ether extract digestibility (53.7 vs. 67.1% for diets without and with FO, respectively). We observed a trend for lower CH4 emission (g/d) and intensity (g/kg of milk) with the high-starch diets compared with the low-starch diets: 396 versus 415g/d on average, respectively, and 14.1 versus 14.9g/kg of milk, respectively. Methane intensity per kilogram of ECM was affected by the interaction between starch and FO, with a positive effect of FO for the LS diet: 14.5 versus 13.3g of CH4/kg of ECM for LS and LSO diets, respectively. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Single Electron Tunneling

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

Ruggiero, Steven T.

Financial support for this project has led to advances in the science of single-electron phenomena. Our group reported the first observation of the so-called ''Coulomb Staircase'', which was produced by tunneling into ultra-small metal particles. This work showed well-defined tunneling voltage steps of width e/C and height e/RC, demonstrating tunneling quantized on the single-electron level. This work was published in a now well-cited Physical Review Letter. Single-electron physics is now a major sub-field of condensed-matter physics, and fundamental work in the area continues to be conducted by tunneling in ultra-small metal particles. In addition, there are now single-electron transistors thatmore » add a controlling gate to modulate the charge on ultra-small photolithographically defined capacitive elements. Single-electron transistors are now at the heart of at least one experimental quantum-computer element, and single-electron transistor pumps may soon be used to define fundamental quantities such as the farad (capacitance) and the ampere (current). Novel computer technology based on single-electron quantum dots is also being developed. In related work, our group played the leading role in the explanation of experimental results observed during the initial phases of tunneling experiments with the high-temperature superconductors. When so-called ''multiple-gap'' tunneling was reported, the phenomenon was correctly identified by our group as single-electron tunneling in small grains in the material. The main focus throughout this project has been to explore single electron phenomena both in traditional tunneling formats of the type metal/insulator/particles/insulator/metal and using scanning tunneling microscopy to probe few-particle systems. This has been done under varying conditions of temperature, applied magnetic field, and with different materials systems. These have included metals, semi-metals, and superconductors. Amongst a number of results, we have verified that clusters of down to one, two, and three metal atoms can be identified with single-electron techniques. We have also, extended the regime of single-electron phenomenology through the observation of single-electron effects in metal droplets in the high-conductance regime.« less

Interspecies scaling and prediction of human clearance: comparison of small- and macro-molecule drugs

PubMed Central

Huh, Yeamin; Smith, David E.; Feng, Meihau Rose

2014-01-01

Human clearance prediction for small- and macro-molecule drugs was evaluated and compared using various scaling methods and statistical analysis.Human clearance is generally well predicted using single or multiple species simple allometry for macro- and small-molecule drugs excreted renally.The prediction error is higher for hepatically eliminated small-molecules using single or multiple species simple allometry scaling, and it appears that the prediction error is mainly associated with drugs with low hepatic extraction ratio (Eh). The error in human clearance prediction for hepatically eliminated small-molecules was reduced using scaling methods with a correction of maximum life span (MLP) or brain weight (BRW).Human clearance of both small- and macro-molecule drugs is well predicted using the monkey liver blood flow method. Predictions using liver blood flow from other species did not work as well, especially for the small-molecule drugs. PMID:21892879

Efficient preparation of graphene liquid cell utilizing direct transfer with large-area well-stitched graphene

NASA Astrophysics Data System (ADS)

Sasaki, Yuki; Kitaura, Ryo; Yuk, Jong Min; Zettl, Alex; Shinohara, Hisanori

2016-04-01

By utilizing graphene-sandwiched structures recently developed in this laboratory, we are able to visualize small droplets of liquids in nanometer scale. We have found that small water droplets as small as several tens of nanometers sandwiched by two single-layer graphene are frequently observed by TEM. Due to the electron beam irradiation during the TEM observation, these sandwiched droplets are frequently moving from one place to another and are subjected to create small bubbles inside. The synthesis of a large area single-domain graphene of high-quality is essential to prepare the graphene sandwiched cell which safely encapsulates the droplets in nanometer size.

Proposed method of producing large optical mirrors Single-point diamond crushing followed by polishing with a small-area tool

NASA Technical Reports Server (NTRS)

Wright, G.; Bryan, J. B.

1986-01-01

Faster production of large optical mirrors may result from combining single-point diamond crushing of the glass with polishing using a small area tool to smooth the surface and remove the damaged layer. Diamond crushing allows a surface contour accurate to 0.5 microns to be generated, and the small area computer-controlled polishing tool allows the surface roughness to be removed without destroying the initial contour. Final contours with an accuracy of 0.04 microns have been achieved.

High Sensitivity SPECT for Small Animals and Plants

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

Mitchell, Gregory S.

Imaging systems using single gamma-ray emitting radioisotopes typically implement collimators in order to form the images. However, a tradeoff in sensitivity is inherent in the use of collimators, and modern preclinical single-photon emission computed tomography (SPECT) systems detect a very small fraction of emitted gamma-rays (<0.3%). We have built a collimator-less system, which can reach sensitivity of 40% for 99mTc imaging, while still producing images of sufficient spatial resolution for certain applications in thin objects such as mice, small plants, and well plates used for in vitro experiments.

Morphological classification of bioaerosols from composting using scanning electron microscopy

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

Tamer Vestlund, A.; FIRA International Ltd., Maxwell Road, Stevenage, Herts SG1 2EW; Al-Ashaab, R.

2014-07-15

Highlights: • Bioaerosols were captured using the filter method. • Bioaerosols were analysed using scanning electron microscope. • Bioaerosols were classified on the basis of morphology. • Single small cells were found more frequently than aggregates and larger cells. • Smaller cells may disperse further than heavier aggregate structures. - Abstract: This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samplesmore » were analysed using scanning electron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2–3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.« less

(abstract) Scaling Nominal Solar Cell Impedances for Array Design

NASA Technical Reports Server (NTRS)

Mueller, Robert L; Wallace, Matthew T.; Iles, Peter

1994-01-01

This paper discusses a task the objective of which is to characterize solar cell array AC impedance and develop scaling rules for impedance characterization of large arrays by testing single solar cells and small arrays. This effort is aimed at formulating a methodology for estimating the AC impedance of the Mars Pathfinder (MPF) cruise and lander solar arrays based upon testing single cells and small solar cell arrays and to create a basis for design of a single shunt limiter for MPF power control of flight solar arrays having very different inpedances.

Fiber optic SERS-based plasmonics nanobiosensing in single living cells

NASA Astrophysics Data System (ADS)

Scaffidi, Jonathan P.; Gregas, Molly K.; Seewaldt, Victoria; Vo-Dinh, Tuan

2009-05-01

We describe the development of small molecule-sensitive plasmonics-active fiber-optic nanoprobes suitable for intracellular bioanalysis in single living human cells using surface-enhanced Raman scattering (SERS) detection. The practical utility of SERS-based fiber-optic nanoprobes is illustrated by measurements of intracellular pH in HMEC- 15/hTERT immortalized "normal" human mammary epithelial cells and PC-3 human prostate cancer cells. The results indicate that fiber-optic nanoprobe insertion and interrogation provide a sensitive and selective means to monitor biologically-relevant small molecules at the single cell level.

Construction of a restriction map and gene map of the lettuce chloroplast small single-copy region using Southern cross-hybridization.

PubMed

Mitchelson, K R

1996-01-01

The small single-copy region (SSCR) of the chloroplast genome of many higher plants typically contain ndh genes encoding proteins that share homology with subunits of the respiratory-chain reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase complex of mitochondria. A map of the lettuce chloroplast SSCR has been determined by Southern cross-hybridization, taking advantage of the high degree of homology between a tobacco small single-copy fragment and a corresponding lettuce chloroplast fragment. The gene order of the SSCR of lettuce and tobacco chloroplasts is similar. The cross-hybridization method can rapidly create a primary gene map of unknown chloroplast fragments, thus providing detailed information of the localization and arrangement of genes and conserved open reading frame regions.

A simple method to reconstruct the molar mass signal of respiratory gas to assess small airways with a double-tracer gas single-breath washout.

PubMed

Port, Johannes; Tao, Ziran; Junger, Annika; Joppek, Christoph; Tempel, Philipp; Husemann, Kim; Singer, Florian; Latzin, Philipp; Yammine, Sophie; Nagel, Joachim H; Kohlhäufl, Martin

2017-11-01

For the assessment of small airway diseases, a noninvasive double-tracer gas single-breath washout (DTG-SBW) with sulfur hexafluoride (SF 6 ) and helium (He) as tracer components has been proposed. It is assumed that small airway diseases may produce typical ventilation inhomogeneities which can be detected within one single tidal breath, when using two tracer components. Characteristic parameters calculated from a relative molar mass (MM) signal of the airflow during the washout expiration phase are analyzed. The DTG-SBW signal is acquired by subtracting a reconstructed MM signal without tracer gas from the signal measured with an ultrasonic sensor during in- and exhalation of the double-tracer gas for one tidal breath. In this paper, a simple method to determine the reconstructed MM signal is presented. Measurements on subjects with and without obstructive lung diseases including the small airways have shown high reliability and reproducibility of this method.

Identification of small molecule inhibitors of cytokinesis and single cell wound repair

PubMed Central

Clark, Andrew G.; Sider, Jenny R.; Verbrugghe, Koen; Fenteany, Gabriel; von Dassow, George; Bement, William M.

2013-01-01

Screening of small molecule libraries offers the potential to identify compounds that inhibit specific biological processes and, ultimately, to identify macromolecules that are important players in such processes. To date, however, most screens of small molecule libraries have focused on identification of compounds that inhibit known proteins or particular steps in a given process, and have emphasized automated primary screens. Here we have used “low tech” in vivo primary screens to identify small molecules that inhibit both cytokinesis and single cell wound repair, two complex cellular processes that possess many common features. The “diversity set”, an ordered array of 1990 compounds available from the National Cancer Institute, was screened in parallel to identify compounds that inhibit cytokinesis in D. excentricus (sand dollar) embryos and single cell wound repair in X. laevis (frog) oocytes. Two small molecules were thus identified: Sph1 and Sph2. Sph1 reduces Rho activation in wound repair and suppresses formation of the spindle midzone during cytokinesis. Sph2 also reduces Rho activation in wound repair and may inhibit cytokinesis by blocking membrane fusion. The results identify two small molecules of interest for analysis of wound repair and cytokinesis, reveal that these processes are more similar than often realized and reveal the potential power of low tech screens of small molecule libraries for analysis of complex cellular processes. PMID:23125193

Coding for Single-Line Transmission

NASA Technical Reports Server (NTRS)

Madison, L. G.

1983-01-01

Digital transmission code combines data and clock signals into single waveform. MADCODE needs four standard integrated circuits in generator and converter plus five small discrete components. MADCODE allows simple coding and decoding for transmission of digital signals over single line.

77 FR 14459 - Notice of Request for Renewal of a Previously Approved Collection

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-09

... guarantee applicants. The revised STLP application is a single, consolidated document that is easier to read... other certified Small Businesses (8a, women-owned, small disadvantaged, HUBZone, veteran owned, and... Small Businesses (8a, women-owned, small disadvantaged, HUBZone, veteran owned, and service disabled...

Observation of Mass Transport Stability and Faraday Instability: Why Stable Single Bubble Sonoluminescence is Possible

NASA Technical Reports Server (NTRS)

Holt, R. G.; Gaitan, D. F.

1996-01-01

Teh region of parameter space (acoustic pressure P(sub a), bubble radius R(sub 0)) in which stable single bubble sonoluminescence (SBSL) occurs in an air-water system is a small fraction of that which is accesible. This is due ot the existence of an island of dissolution at high P(sub a) and small R(sub 0).

Single-cell metabolomics: analytical and biological perspectives.

PubMed

Zenobi, R

2013-12-06

There is currently much interest in broad molecular profiling of single cells; a cell's metabolome-its full complement of small-molecule metabolites-is a direct indicator of phenotypic diversity of single cells and a nearly immediate readout of how cells react to environmental influences. However, the metabolome is very difficult to measure at the single-cell level because of rapid metabolic dynamics, the structural diversity of the molecules, and the inability to amplify or tag small-molecule metabolites. Measurement techniques including mass spectrometry, capillary electrophoresis, and, to a lesser extent, optical spectroscopy and fluorescence detection have led to impressive advances in single-cell metabolomics. Even though none of these methodologies can currently measure the metabolome of a single cell completely, rapidly, and nondestructively, progress has been sufficient such that the field is witnessing a shift from feasibility studies to investigations that yield new biological insight. Particularly interesting fields of application are cancer biology, stem cell research, and monitoring of xenobiotics and drugs in tissue sections at the single-cell level.

Birth weight and prematurity in infants with single ventricle physiology: pediatric heart network infant single ventricle trial screened population.

PubMed

Williams, Richard V; Ravishankar, Chitra; Zak, Victor; Evans, Frank; Atz, Andrew M; Border, William L; Levine, Jami; Li, Jennifer S; Mahony, Lynn; Mital, Seema; Pearson, Gail D; Prakash, Ashwin; Hsu, Daphne T

2010-01-01

Although congenital heart disease is associated with low birth weight and prematurity, there is little information about these birth outcomes in infants with single ventricle physiology. We describe the birth outcomes (i.e., gestational age and birth weight) in neonates with single ventricle physiology screened for enrollment in the Pediatric Heart Network's Infant Single Ventricle Trial, compare these outcomes with US norms, and examine the association of birth outcomes with anatomic diagnosis and race. All neonates with single ventricle physiology presenting to Infant Single Ventricle Trial centers were screened for enrollment. Demographic data and anatomic diagnoses were obtained from medical records. A total of 1245 neonates with single ventricle physiology were screened at 10 centers (63 to 266 per center). Diagnoses included hypoplastic left heart syndrome in 49%, unbalanced atrioventricular septal defect in 12%, and tricuspid atresia in 9%. Preterm birth occurred in 16% of neonates with single ventricle physiology vs. 12% in normal neonates (P < .001), low birth weight (<2.5 kg) in 18% vs. 8% in normals (P < .001), and small for gestational age (<10th percentile by definition) in 22% vs. 10% in normals (P < .001). A genetic syndrome was reported in 8%. The percentage of preterm birth, low birth weight, and small for gestational age was similar between screened neonates with and without hypoplastic left heart syndrome. In this large, contemporary cohort of neonates with single ventricle physiology, rates of preterm birth, low birth weight, and small for gestational age were higher than in the general population, but similar between screened neonates with and without hypoplastic left heart syndrome.

Unsuppressed primordial standard clocks in warm quasi-single field inflation

NASA Astrophysics Data System (ADS)

Tong, Xi; Wang, Yi; Zhou, Siyi

2018-06-01

We study the non-Gaussianities in quasi-single field inflation with a warm inflation background. The thermal effects at small scales can sufficiently enhance the magnitude of the primordial standard clock signal. This scenario offers us the possibility of probing the UV physics of the very early universe without the exponentially small Boltzmann factor when the mass of the isocurvaton is much heavier than Hubble. The thermal effects at small scales can be studied using the flat space thermal field theory, connected to an effective description using non-Bunch-Davies vacuum at large scales, with large clock signal.

Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants

NASA Astrophysics Data System (ADS)

Beer, S.; Streun, M.; Hombach, T.; Buehler, J.; Jahnke, S.; Khodaverdi, M.; Larue, H.; Minwuyelet, S.; Parl, C.; Roeb, G.; Schurr, U.; Ziemons, K.

2010-02-01

Positron emitters such as 11C, 13N and 18F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is 11CO2 since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET™ system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.

Net Weight Issue LLNL DOE-STD-3013 Containers

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

Wilk, P

2008-01-16

The following position paper will describe DOE-STD-3013 container sets No.L000072 and No.L000076, and how they are compliant with DOE-STD-3013-2004. All masses of accountable nuclear materials are measured on LLNL certified balances maintained under an MC&A Program approved by DOE/NNSA LSO. All accountability balances are recalibrated annually and checked to be within calibration on each day that the balance is used for accountability purposes. A statistical analysis of the historical calibration checks from the last seven years indicates that the full-range Limit of Error (LoE, 95% confidence level) for the balance used to measure the mass of the contents of themore » above indicated 3013 containers is 0.185 g. If this error envelope, at the 95% confidence level, were to be used to generate an upper-limit to the measured weight of the containers No.L000072 and No.L000076, the error-envelope would extend beyond the 5.0 kg 3013-standard limit on the package contents by less than 0.3 g. However, this is still well within the intended safety bounds of DOE-STD-3013-2004.« less

Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants.

PubMed

Beer, S; Streun, M; Hombach, T; Buehler, J; Jahnke, S; Khodaverdi, M; Larue, H; Minwuyelet, S; Parl, C; Roeb, G; Schurr, U; Ziemons, K

2010-02-07

Positron emitters such as (11)C, (13)N and (18)F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is (11)CO(2) since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.

Radiation detection measurements with a new ``Buried Junction'' silicon avalanche photodiode

NASA Astrophysics Data System (ADS)

Lecomte, R.; Pepin, C.; Rouleau, D.; Dautet, H.; McIntyre, R. J.; McSween, D.; Webb, P.

1999-02-01

An improved version of a recently developed "Buried Junction" avalanche photodiode (APD), designed for use with scintillators, is described and characterized. This device, also called the "Reverse APD", is designed to have a wide depletion layer and thus low capacitance, but to have high gain only for e-h pairs generated within the first few microns of the depletion layer. Thus it has high gain for light from scintillators emitting in the 400-600 nm range, with relatively low dark current noise and it is relatively insensitive to minimum ionizing particles (MIPs). An additional feature is that the metallurgical junction is at the back of the wafer, leaving the front surface free to be coupled to a scintillator without fear of junction contamination. The modifications made in this device, as compared with the earlier diode, have resulted in a lower excess noise factor, lower dark current, and much-reduced trapping. The electrical and optical characteristics of this device are described and measurements of energy and timing resolution of this device with several scintillators (BGO, LSO and GSO) of potential interest in high-energy physics and PET imaging systems are presented.

Time-Based Readout of a Silicon Photomultiplier (SiPM) for Time of Flight Positron Emission Tomography (TOF-PET)

NASA Astrophysics Data System (ADS)

Powolny, F.; Auffray, E.; Brunner, S. E.; Garutti, E.; Goettlich, M.; Hillemanns, H.; Jarron, P.; Lecoq, P.; Meyer, T.; Schultz-Coulon, H. C.; Shen, W.; Williams, M. C. S.

2011-06-01

Time of flight (TOF) measurements in positron emission tomography (PET) are very challenging in terms of timing performance, and should ideally achieve less than 100 ps FWHM precision. We present a time-based differential technique to read out silicon photomultipliers (SiPMs) which has less than 20 ps FWHM electronic jitter. The novel readout is a fast front end circuit (NINO) based on a first stage differential current mode amplifier with 20 Ω input resistance. Therefore the amplifier inputs are connected differentially to the SiPM's anode and cathode ports. The leading edge of the output signal provides the time information, while the trailing edge provides the energy information. Based on a Monte Carlo photon-generation model, HSPICE simulations were run with a 3 × 3 mm2 SiPM-model, read out with a differential current amplifier. The results of these simulations are presented here and compared with experimental data obtained with a 3 × 3 × 15 mm3 LSO crystal coupled to a SiPM. The measured time coincidence precision and the limitations in the overall timing accuracy are interpreted using Monte Carlo/SPICE simulation, Poisson statistics, and geometric effects of the crystal.

Thermo-Mechanical Modeling of Laser-Mig Hybrid Welding (lmhw)

NASA Astrophysics Data System (ADS)

Kounde, Ludovic; Engel, Thierry; Bergheau, Jean-Michel; Boisselier, Didier

2011-01-01

Hybrid welding is a combination of two different technologies such as laser (Nd: YAG, CO2…) and electric arc welding (MIG, MAG / TIG …) developed to assemble thick metal sheets (over 3 mm) in order to reduce the required laser power. As a matter of fact, hybrid welding is a lso used in the welding of thin materials to benefit from process, deep penetration and gap limit. But the thermo-mechanical behaviour of thin parts assembled by LMHW technology for railway cars production is far from being controlled the modeling and simulation contribute to the assessment of the causes and effects of the thermo mechanical behaviour in the assembled parts. In order to reproduce the morphology of melted and heat-affected zones, two analytic functions were combined to model the heat source of LMHW. On one hand, we applied a so-called "diaboloïd" (DB) which is a modified hyperboloid, based on experimental parameters and the analysis of the macrographs of the welds. On the other hand, we used a so-called "double ellipsoïd" (DE) which takes the MIG only contribution including the bead into account. The comparison between experimental result and numerical result shows a good agreement.

Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes.

PubMed

López-Andarias, Javier; López, Juan Luis; Atienza, Carmen; Brunetti, Fulvio G; Romero-Nieto, Carlos; Guldi, Dirk M; Martín, Nazario

2014-04-29

The construction of ordered single-wall carbon nanotube soft-materials at the nanoscale is currently an important challenge in science. Here we use single-wall carbon nanotubes as a tool to gain control over the crystalline ordering of three-dimensional bulk materials composed of suitably functionalized molecular building blocks. We prepare p-type nanofibres from tripeptide and pentapeptide-containing small molecules, which are covalently connected to both carboxylic and electron-donating 9,10-di(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene termini. Adding small amounts of single-wall carbon nanotubes to the so-prepared p-nanofibres together with the externally controlled self assembly by charge screening by means of Ca(2+) results in new and stable single-wall carbon nanotube-based supramolecular gels featuring remarkably long-range internal order.

Single-tube hydroponics as a novel idea for small-scale production of crop seed in a plant incubator.

PubMed

Kuroda, Masaharu; Ikenaga, Sachiko

2015-01-01

We present a novel protocol for small-scale production of crop seed in a plant incubator termed "Single-tube hydroponics." Our protocol minimizes the materials and methods for cultivation whereby a large number of independent plants can be cultured in a limited space. This study may aid in the improvement of crop seed components, especially in the cultivation of transgenic plants.

Clinical outcomes in real-world patients with small vessel disease treated with XIENCE V® everolimus-eluting stents: one year results from the XIENCE V® USA condition of approval post-market study.

PubMed

Hermiller, James B; Rutledge, David R; Mao, Vivian W; Zhao, Weiying; Wang, Jin; Gruberg, Luis; Lombardi, William; Sharma, Samin K; Krucoff, Mitchell W

2014-07-01

The purpose of this study was to evaluate the 1-year clinical outcomes of more complex XIENCE V USA real-world patients with small versus nonsmall vessel lesions. Patients with small vessel lesions undergoing coronary stent placement are at higher risk of major adverse cardiac events. Improved safety and efficacy of XIENCE V everolimus eluting stents (EES) have been previously demonstrated in selected low-risk small vessel populations in randomized clinical trials. The XIENCE V USA study was a condition of approval, single-arm study in unselected real-world patients. Baseline and 1-year clinical outcomes were compared between XIENCE V USA patients who received a single 2.5 mm stent (small vessel group, N = 838) and patients implanted with a single >2.5 mm stent (non-small vessel group, N = 2,015). Mean reference vessel diameter was 2.55 ± 0.36 and 3.25 ± 0.46 mm in the small and non-small vessel groups, respectively (P < 0.001). Small vessel group had more females, presented with a higher rate of diabetes, and had more complex lesion characteristics. The definite or probable ST rates analyzed using Kaplan-Meier method were low and not significantly different between the groups at 0.37 and 0.40% for the small and nonsmall vessel group (P = 0.88), respectively. The composite rate of cardiac death or MI was comparable at 4.5% for the small and 5.1% for the non-small vessel 1 groups (P = 0.57). The 1-year target lesion revascularization rate was also comparable in the small vessel group (3.8% vs. 3.0%, P = 0.35). Despite gender difference, higher prevalence of diabetes and more complex lesions in the small vessel groups, the 1-year clinical outcomes were similar in both small and nonsmall vessel groups. These results demonstrate the therapeutic benefit of XIENCE V EES in a real-world all inclusive patient population with small vessel disease. © 2013 Wiley Periodicals, Inc.

24 CFR 3280.802 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... panelboard means a single panel or a group of panel units designed for assembly in the form of a single panel... control of light, heat, or power circuits of small individual as well as aggregate capacity; designed to...) Panelboard means a single panel or group of panel units designed for assembly in the form of a single panel...

Towards mapping of rock walls using a UAV-mounted 2D laser scanner in GPS denied environments

NASA Astrophysics Data System (ADS)

Turner, Glen

In geotechnical engineering, the stability of rock excavations and walls is estimated by using tools that include a map of the orientations of exposed rock faces. However, measuring these orientations by using conventional methods can be time consuming, sometimes dangerous, and is limited to regions of the exposed rock that are reachable by a human. This thesis introduces a 2D, simulated, quadcopter-based rock wall mapping algorithm for GPS denied environments such as underground mines or near high walls on surface. The proposed algorithm employs techniques from the field of robotics known as simultaneous localization and mapping (SLAM) and is a step towards 3D rock wall mapping. Not only are quadcopters agile, but they can hover. This is very useful for confined spaces such as underground or near rock walls. The quadcopter requires sensors to enable self localization and mapping in dark, confined and GPS denied environments. However, these sensors are limited by the quadcopter payload and power restrictions. Because of these restrictions, a light weight 2D laser scanner is proposed. As a first step towards a 3D mapping algorithm, this thesis proposes a simplified scenario in which a simulated 1D laser range finder and 2D IMU are mounted on a quadcopter that is moving on a plane. Because the 1D laser does not provide enough information to map the 2D world from a single measurement, many measurements are combined over the trajectory of the quadcopter. Least Squares Optimization (LSO) is used to optimize the estimated trajectory and rock face for all data collected over the length of a light. Simulation results show that the mapping algorithm developed is a good first step. It shows that by combining measurements over a trajectory, the scanned rock face can be estimated using a lower-dimensional range sensor. A swathing manoeuvre is introduced as a way to promote loop closures within a short time period, thus reducing accumulated error. Some suggestions on how to improve the algorithm are also provided.

Modality comparison for small animal radiotherapy: A simulation study

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

Bazalova, Magdalena, E-mail: bazalova@stanford.edu; Nelson, Geoff; Noll, John M.

Purpose: Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities. Methods: This paper presents a comparison of dose distributions generated by the three approaches—a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCTmore » scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes. Results: All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by the SARRP plan due to the sensitivity of the lower energy microCT beam to target heterogeneities and image noise. Conclusions: The two treatment planning examples demonstrate that modern small animal radiotherapy techniques employing image guidance, variable collimation, and multiple beam angles deliver superior dose distributions to small animal tumors as compared to conventional treatments using a single-field irradiator. For deep-seated mouse tumors, however, higher-energy conformal radiotherapy could result in higher doses to critical organs compared to lower-energy conformal radiotherapy. Treatment planning optimization for small animal radiotherapy should therefore be developed to take full advantage of the novel conformal systems.« less

Antibody-Mediated Small Molecule Detection Using Programmable DNA-Switches.

PubMed

Rossetti, Marianna; Ippodrino, Rudy; Marini, Bruna; Palleschi, Giuseppe; Porchetta, Alessandro

2018-06-13

The development of rapid, cost-effective, and single-step methods for the detection of small molecules is crucial for improving the quality and efficiency of many applications ranging from life science to environmental analysis. Unfortunately, current methodologies still require multiple complex, time-consuming washing and incubation steps, which limit their applicability. In this work we present a competitive DNA-based platform that makes use of both programmable DNA-switches and antibodies to detect small target molecules. The strategy exploits both the advantages of proximity-based methods and structure-switching DNA-probes. The platform is modular and versatile and it can potentially be applied for the detection of any small target molecule that can be conjugated to a nucleic acid sequence. Here the rational design of programmable DNA-switches is discussed, and the sensitive, rapid, and single-step detection of different environmentally relevant small target molecules is demonstrated.

Small-mammal responses to pine regeneration treatments in the Ouachita Mountains of Arkansas and Oklahoma, USA

Treesearch

Roger W. Perry; Ronald E. Thill

2005-01-01

We compared the initial effects of four forest regeneration treatments (single-tree selection, group selection, shelterwood, and clearcut), and unharvested controls (mature, second-growth forest) on relative abundance of small mammals and small-mammal habitat throughout the Ouachita Mountains of western Arkansas and eastern Oklahoma. We compared small-mammal capture...

Impact of target-to-background ratio, target size, emission scan duration, and activity on physical figures of merit for a 3D LSO-based whole body PET/CT scanner.

PubMed

Brambilla, M; Matheoud, R; Secco, C; Sacchetti, G; Comi, S; Rudoni, M; Carriero, A; Inglese, E

2007-10-01

The aim of our work is to describe the way in which physical figures of merit such as contrast-to-noise ratio (CNR) behave when varying acquisition parameters such as emission scan duration (ESD) or activity at the start of acquisition (A(acq)) that in clinical practice can be selected by the user, or object properties such as target dimensions or target-to-background (T/B) ratio, which depend uniquely on the intrinsic characteristics of the object being imaged. Figures of merit, used to characterize image quality and quantitative accuracy for a 3D-LSO based PET/CT scanner, were studied as a function of ESD and A(acq) for different target sizes and T/B ratios using a multivariate approach in a wide range of conditions approaching the ones that can be encountered in clinical practice. An annular ring of water bags of 3 cm thickness was fitted over an IEC phantom in order to obtain counting rates similar to those found in average patients. The average scatter fraction (SF) of the modified IEC phantom was similar to the mean SF measured on patients with a similar scanner. A supplemental set of micro-hollow spheres was positioned inside the phantom. The NEMA NU 2-2001 scatter phantom was positioned at the end of the IEC phantom to approximate the clinical situation of having activity that extends beyond the scanner. The phantoms were filled with a solution of water and 18F (12 kBq/mL) and the spheres with various T/B ratios of 22.5, 10.3, and 3.6. Sequential imaging was performed to acquire PET images with varying background activity concentrations of about 12, 9, 6.4, 5.3, and 3.1 kBq/mL, positioned on the linear portion of the phantom's NECR curve, well below peak NECR of 61.2 kcps that is reached at 31.8 kBq/mL. The ESD was set to 1, 2, 3, and 4 min/bed. With T/B ratios of 3.6, 10.3, and 22.5, the 13.0, 8.1, and 6.5 mm spheres were detectable for the whole ranges of background activity concentration and ESD, respectively. The ESD resulted as the most significant predictor of CNR variance, followed by T/B ratio and the cross sectional area of the given sphere. Only last comes A(acq) with a weight more than halved with respect to ESD. Thus, raising ESD seems to be much more effective than raising A(acq) in order to obtain higher CNR, which is the physical figure of merit closely related with target detectability, at least in the simple task of the signal known exactly background known exactly model.

quenched-smFISH: Counting small RNA in Pathogenic Bacteria

NASA Astrophysics Data System (ADS)

Shepherd, Douglas; Li, Nan; Micheva-Viteva, Sofiya; Munsky, Brian; Hong-Geller, Elizabeth; Werner, James

2014-03-01

Here, we present a modification to single-molecule fluorescence in situ hybridization, quenched smFISH (q-smFISH), that enables quantitative detection and analysis of small RNA (sRNA) expressed in bacteria. We show that short nucleic acid targets can be detected when the background of unbound singly dye-labeled DNA oligomers is reduced through hybridization with a set of complementary DNA oligomers labeled with a fluorescence quencher. Exploiting an automated, multi-color wide-field microscope and GPU-accelerated data analysis package, we analyzed the statistics of sRNA expression in thousands of individual Yersinia pseudotuberculosis and Yersinia pestis bacteria before and during a simulated infection. Before infection, we find only a small fraction of either bacteria express the small RNAs YSR35 or YSP8. The copy numbers of these RNA are increased during simulated infection, suggesting a role in pathogenesis. The ability to directly quantify expression level changes of sRNA in single cells as a function of external stimuli provides key information on the role of sRNA in bacterial regulatory networks.

Multiparameter estimation with single photons—linearly-optically generated quantum entanglement beats the shotnoise limit

NASA Astrophysics Data System (ADS)

You, Chenglong; Adhikari, Sushovit; Chi, Yuxi; LaBorde, Margarite L.; Matyas, Corey T.; Zhang, Chenyu; Su, Zuen; Byrnes, Tim; Lu, Chaoyang; Dowling, Jonathan P.; Olson, Jonathan P.

2017-12-01

It was suggested in (Motes et al 2015 Phys. Rev. Lett. 114 170802) that optical networks with relatively inexpensive overheads—single photon Fock states, passive optical elements, and single photon detection—can show significant improvements over classical strategies for single-parameter estimation, when the number of modes in the network is small (n< 7). A similar case was made in (Humphreys et al 2013 Phys. Rev. Lett. 111 070403) for multi-parameter estimation, where measurement is instead made using photon-number resolving detectors. In this paper, we analytically compute the quantum Cramér-Rao bound to show these networks can have a constant-factor quantum advantage in multi-parameter estimation for even large number of modes. Additionally, we provide a simplified measurement scheme using only single-photon (on-off) detectors that is capable of approximately obtaining this sensitivity for a small number of modes.

Single-electron random-number generator (RNG) for highly secure ubiquitous computing applications

NASA Astrophysics Data System (ADS)

Uchida, Ken; Tanamoto, Tetsufumi; Fujita, Shinobu

2007-11-01

Since the security of all modern cryptographic techniques relies on unpredictable and irreproducible digital keys generated by random-number generators (RNGs), the realization of high-quality RNG is essential for secure communications. In this report, a new RNG, which utilizes single-electron phenomena, is proposed. A room-temperature operating silicon single-electron transistor (SET) having nearby an electron pocket is used as a high-quality, ultra-small RNG. In the proposed RNG, stochastic single-electron capture/emission processes to/from the electron pocket are detected with high sensitivity by the SET, and result in giant random telegraphic signals (GRTS) on the SET current. It is experimentally demonstrated that the single-electron RNG generates extremely high-quality random digital sequences at room temperature, in spite of its simple configuration. Because of its small-size and low-power properties, the single-electron RNG is promising as a key nanoelectronic device for future ubiquitous computing systems with highly secure mobile communication capabilities.

Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon

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

Brodsky, S.J.; Gardner, S.

2006-08-23

The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.

Fluorescence quenching by TEMPO: a sub-30 A single-molecule ruler.

PubMed

Zhu, Peizhi; Clamme, Jean-Pierre; Deniz, Ashok A

2005-11-01

A series of DNA molecules labeled with 5-carboxytetramethylrhodamine (5-TAMRA) and the small nitroxide radical TEMPO were synthesized and tested to investigate whether the intramolecular quenching efficiency can be used to measure short intramolecular distances in small ensemble and single-molecule experiments. In combination with distance calculations using molecular mechanics modeling, the experimental results from steady-state ensemble fluorescence and fluorescence correlation spectroscopy measurements both show an exponential decrease in the quenching rate constant with the dye-quencher distance in the 10-30 A range. The results demonstrate that TEMPO-5-TAMRA fluorescence quenching is a promising method to measure short distance changes within single biomolecules.

Detection of single nano-defects in photonic crystals between crossed polarizers.

PubMed

Grepstad, Jon Olav; Kaspar, Peter; Johansen, Ib-Rune; Solgaard, Olav; Sudbø, Aasmund

2013-12-16

We investigate, by simulations and experiments, the light scattering of small particles trapped in photonic crystal membranes supporting guided resonance modes. Our results show that, due to amplified Rayleigh small particle scattering, such membranes can be utilized to make a sensor that can detect single nano-particles. We have designed a biomolecule sensor that uses cross-polarized excitation and detection for increased sensitivity. Estimated using Rayleigh scattering theory and simulation results, the current fabricated sensor has a detection limit of 26 nm, corresponding to the size of a single virus. The sensor can potentially be made both cheap and compact, to facilitate use at point-of-care.

Sensitive Small Area Photometer

ERIC Educational Resources Information Center

Levenson, M. D.

1970-01-01

Describes a simple photometer capable of measuring small light intensities over small areas. The inexpensive, easy-to- construct instrument is intended for use in a student laboratory to measure the light intensities in a diffraction experiment from single or multiple slits. Typical experimental results are presented along with the theoretical…

Cucurbituril mediated single molecule detection and identification via recognition tunneling.

PubMed

Xiao, Bohuai; Liang, Feng; Liu, Simin; Im, JongOne; Li, Yunchuan; Liu, Jing; Zhang, Bintian; Zhou, Jianghao; He, Jin; Chang, Shuai

2018-06-08

Recognition tunneling (RT) is an emerging technique for investigating single molecules in a tunnel junction. We have previously demonstrated its capability of single molecule detection and identification, as well as probing the dynamics of intermolecular bonding at the single molecule level. Here by introducing cucurbituril as a new class of recognition molecule, we demonstrate a powerful platform for electronically investigating the host-guest chemistry at single molecule level. In this report, we first investigated the single molecule electrical properties of cucurbituril in a tunnel junction. Then we studied two model guest molecules, aminoferrocene and amantadine, which were encapsulated by cucurbituril. Small differences in conductance and lifetime can be recognized between the host-guest complexes with the inclusion of different guest molecules. By using a machine learning algorithm to classify the RT signals in a hyper dimensional space, the accuracy of guest molecule recognition can be significantly improved, suggesting the possibility of using cucurbituril molecule for single molecule identification. This work enables a new class of recognition molecule for RT technique and opens the door for detecting a vast variety of small molecules by electrical measurements.

A trypanosomal orthologue of an intermembrane space chaperone has a non-canonical function in biogenesis of the single mitochondrial inner membrane protein translocase.

PubMed

Wenger, Christoph; Oeljeklaus, Silke; Warscheid, Bettina; Schneider, André; Harsman, Anke

2017-08-01

Mitochondrial protein import is essential for Trypanosoma brucei across its life cycle and mediated by membrane-embedded heterooligomeric protein complexes, which mainly consist of trypanosomatid-specific subunits. However, trypanosomes contain orthologues of small Tim chaperones that escort hydrophobic proteins across the intermembrane space. Here we have experimentally analyzed three novel trypanosomal small Tim proteins, one of which contains only an incomplete Cx3C motif. RNAi-mediated ablation of TbERV1 shows that their import, as in other organisms, depends on the MIA pathway. Submitochondrial fractionation combined with immunoprecipitation and BN-PAGE reveals two pools of small Tim proteins: a soluble fraction forming 70 kDa complexes, consistent with hexamers and a second fraction that is tightly associated with the single trypanosomal TIM complex. RNAi-mediated ablation of the three proteins leads to a growth arrest and inhibits the formation of the TIM complex. In line with these findings, the changes in the mitochondrial proteome induced by ablation of one small Tim phenocopy the effects observed after ablation of TbTim17. Thus, the trypanosomal small Tims play an unexpected and essential role in the biogenesis of the single TIM complex, which for one of them is not linked to import of TbTim17.

Single-chain antibody-delivered Livin siRNA inhibits human malignant melanoma growth in vitro and in vivo.

PubMed

Wang, Hao; Yang, Yifei; Wang, Wei; Guan, Bing; Xun, Meng; Zhang, Hai; Wang, Ziling; Zhao, Yong

2017-05-01

Although gene therapy has brought new insights into the treatment of malignant melanoma, targeting delivery of nucleic acid which targets critical oncogene/anti-oncogene in vivo is still a bottleneck in the therapeutic application. Our previous in vitro studies have found that the oncogene Livin could serve as a potential molecular target by small interfering RNA for gene therapy of malignant melanoma. However, how to transport Livin small interfering RNA into malignant melanoma cells specifically and efficiently in vivo needs further investigation. Cumulative evidence has suggested that single-chain antibody-mediated small interfering RNA targeted delivery is an effective way to silence specific genes in human cancer cells. Indeed, this study designed a protamine-single-chain antibody fusion protein, anti-MM scFv-tP, to deliver Livin small interfering RNA into LiBr cells. Further experiments confirmed the induction of cell apoptosis and suppression of cell proliferation by anti-MM scFv-tP in LiBr cells, along with efficient silence of Livin gene both in vitro and in vivo. Altogether, our findings provide a feasible approach to transport Livin small interfering RNA to malignant melanoma cells which would be a new therapeutic strategy for combating malignant melanoma.

A Single Session of rTMS Enhances Small-Worldness in Writer's Cramp: Evidence from Simultaneous EEG-fMRI Multi-Modal Brain Graph.

PubMed

Bharath, Rose D; Panda, Rajanikant; Reddam, Venkateswara Reddy; Bhaskar, M V; Gohel, Suril; Bhardwaj, Sujas; Prajapati, Arvind; Pal, Pramod Kumar

2017-01-01

Background and Purpose : Repetitive transcranial magnetic stimulation (rTMS) induces widespread changes in brain connectivity. As the network topology differences induced by a single session of rTMS are less known we undertook this study to ascertain whether the network alterations had a small-world morphology using multi-modal graph theory analysis of simultaneous EEG-fMRI. Method : Simultaneous EEG-fMRI was acquired in duplicate before (R1) and after (R2) a single session of rTMS in 14 patients with Writer's Cramp (WC). Whole brain neuronal and hemodynamic network connectivity were explored using the graph theory measures and clustering coefficient, path length and small-world index were calculated for EEG and resting state fMRI (rsfMRI). Multi-modal graph theory analysis was used to evaluate the correlation of EEG and fMRI clustering coefficients. Result : A single session of rTMS was found to increase the clustering coefficient and small-worldness significantly in both EEG and fMRI ( p < 0.05). Multi-modal graph theory analysis revealed significant modulations in the fronto-parietal regions immediately after rTMS. The rsfMRI revealed additional modulations in several deep brain regions including cerebellum, insula and medial frontal lobe. Conclusion : Multi-modal graph theory analysis of simultaneous EEG-fMRI can supplement motor physiology methods in understanding the neurobiology of rTMS in vivo . Coinciding evidence from EEG and rsfMRI reports small-world morphology for the acute phase network hyper-connectivity indicating changes ensuing low-frequency rTMS is probably not "noise".

Scatter characterization and correction for simultaneous multiple small-animal PET imaging.

PubMed

Prasad, Rameshwar; Zaidi, Habib

2014-04-01

The rapid growth and usage of small-animal positron emission tomography (PET) in molecular imaging research has led to increased demand on PET scanner's time. One potential solution to increase throughput is to scan multiple rodents simultaneously. However, this is achieved at the expense of deterioration of image quality and loss of quantitative accuracy owing to enhanced effects of photon attenuation and Compton scattering. The purpose of this work is, first, to characterize the magnitude and spatial distribution of the scatter component in small-animal PET imaging when scanning single and multiple rodents simultaneously and, second, to assess the relevance and evaluate the performance of scatter correction under similar conditions. The LabPET™-8 scanner was modelled as realistically as possible using Geant4 Application for Tomographic Emission Monte Carlo simulation platform. Monte Carlo simulations allow the separation of unscattered and scattered coincidences and as such enable detailed assessment of the scatter component and its origin. Simple shape-based and more realistic voxel-based phantoms were used to simulate single and multiple PET imaging studies. The modelled scatter component using the single-scatter simulation technique was compared to Monte Carlo simulation results. PET images were also corrected for attenuation and the combined effect of attenuation and scatter on single and multiple small-animal PET imaging evaluated in terms of image quality and quantitative accuracy. A good agreement was observed between calculated and Monte Carlo simulated scatter profiles for single- and multiple-subject imaging. In the LabPET™-8 scanner, the detector covering material (kovar) contributed the maximum amount of scatter events while the scatter contribution due to lead shielding is negligible. The out-of field-of-view (FOV) scatter fraction (SF) is 1.70, 0.76, and 0.11% for lower energy thresholds of 250, 350, and 400 keV, respectively. The increase in SF ranged between 25 and 64% when imaging multiple subjects (three to five) of different size simultaneously in comparison to imaging a single subject. The spill-over ratio (SOR) increases with increasing the number of subjects in the FOV. Scatter correction improved the SOR for both water and air cold compartments of single and multiple imaging studies. The recovery coefficients for different body parts of the mouse whole-body and rat whole-body anatomical models were improved for multiple imaging studies following scatter correction. The magnitude and spatial distribution of the scatter component in small-animal PET imaging of single and multiple subjects simultaneously were characterized, and its impact was evaluated in different situations. Scatter correction improves PET image quality and quantitative accuracy for single rat and simultaneous multiple mice and rat imaging studies, whereas its impact is insignificant in single mouse imaging.

14th Annual Small Business Conference

DTIC Science & Technology

2010-11-18

Government Contracting, Small Business Administration 5:45 pm - 7:45 pm RECEPTION IN DISPLAY AREA 14TH ANNUAL SMALL BUSINESS CONFERENCE...as a lobbyist for a large multi-national conglomerate that included among its subsidiaries movie companies, sports teams, financial services companies...Past Performance /Small Business Participation > M.1 Basis of Award: The Government plans to award a single contract for the Fighting Trailer

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

Chang, Yung-Ting; Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan 10617, Taiwan; Liu, Shun-Wei

Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less lightmore » than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.« less

Single-Sex Education in Public School Settings

ERIC Educational Resources Information Center

Crawford-Ferre, Heather Glynn; Wiest, Lynda R.

2013-01-01

Although researchers have studied the effectiveness of single-sex education (SSE), the findings have been mixed. This exploratory study reports the perceived goals and effectiveness of single-sex education based on interviews with a small group of educators involved with SSE in various ways. Research participants included a school principal and…

The Effects of Single-Sex and Coeducational Secondary Schooling on Girls' Achievement.

ERIC Educational Resources Information Center

Daly, Peter

1996-01-01

The effect of coeducational and single-sex secondary schooling on female students' academic achievement was examined. Reexamination of earlier survey data from Northern Ireland studied six outcomes related to student performance on public examinations. Results indicated a small achievement advantage for single-sex schooling (not significant…

RL-10 Based Combined Cycle For A Small Reusable Single-Stage-To-Orbit Launcher

NASA Technical Reports Server (NTRS)

Balepin, Vladimir; Price, John; Filipenco, Victor

1999-01-01

This paper discusses a new application of the combined propulsion known as the KLIN(TM) cycle, consisting of a thermally integrated deeply cooled turbojet (DCTJ) and liquid rocket engine (LRE). If based on the RL10 rocket engine family, the KLIN (TM) cycle makes a small single-stage-to-orbit (SSTO) reusable launcher feasible and economically very attractive. Considered in this paper are the concept and parameters of a small SSTO reusable launch vehicle (RLV) powered by the KLIN (TM) cycle (sSSTO(TM)) launcher. Also discussed are the benefits of the small launcher, the reusability, and the combined cycle application. This paper shows the significant reduction of the gross take off weight (GTOW) and dry weight of the KLIN(TM) cycle-powered launcher compared to an all-rocket launcher.

The rewritable effects of bonded magnet for large starting torque and high efficiency in the small power single-phase written pole motor

NASA Astrophysics Data System (ADS)

Choi, Jae-Hak; Lee, Sung-Ho

2009-04-01

This paper presents a single-phase written pole motor using a bonded ring magnet for the small power home application. The motor has an exciter pole structure inside the stator and hybrid characteristics of an induction motor and permanent magnet motor. The design parameters and operating characteristics of the hybrid concept motor are investigated to increase starting torque and efficiency, which is most important for the small power home application. Larger starting torque and higher efficiency than those of the conventional induction motor could be obtained by using the rewritable characteristics of bonded magnet on the starting and running conditions.

Microdissection and molecular manipulation of single chromosomes in woody fruit trees with small chromosomes using pomelo (Citrus grandis) as a model. I. Construction of single chromosomal DNA libraries.

PubMed

Huang, D; Wu, W; Zhou, Y; Hu, Z; Lu, L

2004-05-01

Construction of single chromosomal DNA libraries by means of chromosome microdissection and microcloning will be useful for genomic research, especially for those species that have not been extensively studied genetically. Application of the technology of microdissection and microcloning to woody fruit plants has not been reported hitherto, largely due to the generally small sizes of metaphase chromosomes and the difficulty of chromosome preparation. The present study was performed to establish a method for single chromosome microdissection and microcloning in woody fruit species using pomelo as a model. The standard karyotype of a pomelo cultivar ( Citrus grandis cv. Guanxi) was established based on 20 prometaphase photomicrographs. According to the standard karyotype, chromosome 1 was identified and isolated with fine glass microneedles controlled by a micromanipulator. DNA fragments ranging from 0.3 kb to 2 kb were acquired from the isolated single chromosome 1 via two rounds of PCR mediated by Sau3A linker adaptors and then cloned into T-easy vectors to generate a DNA library of chromosome 1. Approximately 30,000 recombinant clones were obtained. Evaluation based on 108 randomly selected clones showed that the sizes of the cloned inserts varied from 0.5 kb to 1.5 kb with an average of 860 bp. Our research suggests that microdissection and microcloning of single small chromosomes in woody plants is feasible.

Fluorescence Quenching by TEMPO: A Sub-30 Å Single-Molecule Ruler

PubMed Central

Zhu, Peizhi; Clamme, Jean-Pierre; Deniz, Ashok A.

2005-01-01

A series of DNA molecules labeled with 5-carboxytetramethylrhodamine (5-TAMRA) and the small nitroxide radical TEMPO were synthesized and tested to investigate whether the intramolecular quenching efficiency can be used to measure short intramolecular distances in small ensemble and single-molecule experiments. In combination with distance calculations using molecular mechanics modeling, the experimental results from steady-state ensemble fluorescence and fluorescence correlation spectroscopy measurements both show an exponential decrease in the quenching rate constant with the dye-quencher distance in the 10–30 Å range. The results demonstrate that TEMPO-5-TAMRA fluorescence quenching is a promising method to measure short distance changes within single biomolecules. PMID:16199509

Small-signal amplifier based on single-layer MoS2

NASA Astrophysics Data System (ADS)

Radisavljevic, Branimir; Whitwick, Michael B.; Kis, Andras

2012-07-01

In this letter we demonstrate the operation of an analog small-signal amplifier based on single-layer MoS2, a semiconducting analogue of graphene. Our device consists of two transistors integrated on the same piece of single-layer MoS2. The high intrinsic band gap of 1.8 eV allows MoS2-based amplifiers to operate with a room temperature gain of 4. The amplifier operation is demonstrated for the frequencies of input signal up to 2 kHz preserving the gain higher than 1. Our work shows that MoS2 can effectively amplify signals and that it could be used for advanced analog circuits based on two-dimensional materials.

Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

DOE PAGES

Márquez, Francisco; López, Vicente; Morant, Carmen; ...

2010-01-01

Arrmore » ays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 ° C . The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.« less

Investigation of current university research concerning energy conversion and conservation in small single-family dwellings

NASA Technical Reports Server (NTRS)

Grossman, G. R.; Roberts, A. S., Jr.

1975-01-01

An investigation was made of university research concerning energy conversion and conservation techniques which may be applied in small single-family residences. Information was accumulated through published papers, progress reports, telephone conversations, and personal interviews. A synopsis of each pertinent investigation is given. Finally, a discussion of the synopses is presented and recommendations are made concerning the applicability of concepts for the design and construction of NASA-Langley Research Center's proposed Technology Utilization House in Hampton, Virginia.

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

Bazalova, Magdalena, E-mail: bazalova@stanford.edu; Nelson, Geoff; Noll, John M.

Purpose: Small animal radiation therapy has advanced significantly in recent years. Whereas in the past dose was delivered using a single beam and a lead shield for sparing of healthy tissue, conformal doses can be now delivered using more complex dedicated small animal radiotherapy systems with image guidance. The goal of this paper is to investigate dose distributions for three small animal radiation treatment modalities. Methods: This paper presents a comparison of dose distributions generated by the three approaches—a single-field irradiator with a 200 kV beam and no image guidance, a small animal image-guided conformal system based on a modified microCTmore » scanner with a 120 kV beam developed at Stanford University, and a dedicated conformal system, SARRP, using a 220 kV beam developed at Johns Hopkins University. The authors present a comparison of treatment plans for the three modalities using two cases: a mouse with a subcutaneous tumor and a mouse with a spontaneous lung tumor. A 5 Gy target dose was calculated using the EGSnrc Monte Carlo codes. Results: All treatment modalities generated similar dose distributions for the subcutaneous tumor case, with the highest mean dose to the ipsilateral lung and bones in the single-field plan (0.4 and 0.4 Gy) compared to the microCT (0.1 and 0.2 Gy) and SARRP (0.1 and 0.3 Gy) plans. The lung case demonstrated that due to the nine-beam arrangements in the conformal plans, the mean doses to the ipsilateral lung, spinal cord, and bones were significantly lower in the microCT plan (2.0, 0.4, and 1.9 Gy) and the SARRP plan (1.5, 0.5, and 1.8 Gy) than in single-field irradiator plan (4.5, 3.8, and 3.3 Gy). Similarly, the mean doses to the contralateral lung and the heart were lowest in the microCT plan (1.5 and 2.0 Gy), followed by the SARRP plan (1.7 and 2.2 Gy), and they were highest in the single-field plan (2.5 and 2.4 Gy). For both cases, dose uniformity was greatest in the single-field irradiator plan followed by the SARRP plan due to the sensitivity of the lower energy microCT beam to target heterogeneities and image noise. Conclusions: The two treatment planning examples demonstrate that modern small animal radiotherapy techniques employing image guidance, variable collimation, and multiple beam angles deliver superior dose distributions to small animal tumors as compared to conventional treatments using a single-field irradiator. For deep-seated mouse tumors, however, higher-energy conformal radiotherapy could result in higher doses to critical organs compared to lower-energy conformal radiotherapy. Treatment planning optimization for small animal radiotherapy should therefore be developed to take full advantage of the novel conformal systems.« less

Changes and Trends in Small Disadvantaged Business (SDB) Programs.

DTIC Science & Technology

1996-12-01

Since the late 1960s, it has been the policy of the Federal Government to support the development of small disadvantaged businesses (SDBs) owned and...set forth in Adarand case. This study recommends a consolidated single piece of legislative proposal that can best serve the public in promoting small disadvantaged businesses.

Initial small mammal responses to alternative pine regeneration methods in Arkansas and Oklahoma: preliminary findings

Treesearch

Ronald E. Thill; Roger W. Perry; Nancy E. Koerth; Philip A. Tappe; David G. Peitz

2004-01-01

Abstract - We studied winter small mammal communities in the Ouachita Mountains of west-central Arkansas and eastern Oklahoma using Sherman live traps in four replications of four regeneration treatments (clearcut/plant, shelterwood, single-tree selection, and group selection), plus four mature, untreated "controls." Data on relative small...

A High-Resolution Endoscope of Small Diameter Using Electromagnetically Vibration of Single Fiber

NASA Astrophysics Data System (ADS)

Matsunaga, Tadao; Hino, Ryunosuke; Makishi, Wataru; Esashi, Masayoshi; Haga, Yoichi

For high resolution visual inspection in the narrow space of the human body, small diameter endoscope has been developed which utilize electromagnetically vibration of single fiber. Thin endoscopes are effective for inspection in the narrow space of the human body, for example, in the blood vessel, lactiferous duct for detection infiltration of breast cancer, and periodontal gap between gingiva and tooth. This endoscope consists of single optical fiber and photofabricated driving coils. A collimator lens and a cylindrical permanent magnet are fixed on the optical fiber, and the tilted driving coils have been patterned on a 1.08 mm outer diameter thin tube. The fiber is positioned at the center of the tube which is patterned the coils. When an electrical alternating current at the resonance frequency is supplied to the coils, the permanent magnet which is fixed to the fiber is vibrated electromagnetically and scanned one or two dimensionally. This paper reports small diameter endoscope by using electromagnetically vibration of single fiber. Optical coherence tomography imaging has also been carried out with the fabricated endoscope and cross-section image of sub-surface skin of thumb was observed.

In vivo imaging of T cell lymphoma infiltration process at the colon.

PubMed

Ueda, Yoshibumi; Ishiwata, Toshiyuki; Shinji, Seiichi; Arai, Tomio; Matsuda, Yoko; Aida, Junko; Sugimoto, Naotoshi; Okazaki, Toshiro; Kikuta, Junichi; Ishii, Masaru; Sato, Moritoshi

2018-03-05

The infiltration and proliferation of cancer cells in the secondary organs are of great interest, since they contribute to cancer metastasis. However, cancer cell dynamics in the secondary organs have not been elucidated at single-cell resolution. In the present study, we established an in vivo model using two-photon microscopy to observe how infiltrating cancer cells form assemblages from single T-cell lymphomas, EL4 cells, in the secondary organs. Using this model, after inoculation of EL4 cells in mice, we discovered that single EL4 cells infiltrated into the colon. In the early stage, sporadic elongated EL4 cells became lodged in small blood vessels. Real-time imaging revealed that, whereas more than 70% of EL4 cells did not move during a 1-hour observation, other EL4 cells irregularly moved even in small vessels and dynamically changed shape upon interacting with other cells. In the late stages, EL4 cells formed small nodules composed of several EL4 cells in blood vessels as well as crypts, suggesting the existence of diverse mechanisms of nodule formation. The present in vivo imaging system is instrumental to dissect cancer cell dynamics during metastasis in other organs at the single-cell level.

THE SCHOOL PARK.

ERIC Educational Resources Information Center

FISCHER, JOHN H.

TO ASSIST IN DESEGREGATION, VARIOUS MODELS FOR THE SCHOOL PARK ARE PROPOSED--(1) ASSEMBLING ALL STUDENTS AND SCHOOLS OF A SMALL OR MEDIUM-SIZED COMMUNITY ON A SINGLE CAMPUS, (2) SERVING ONE SECTION OF A LARGE CITY, (3) CENTERING ALL SCHOOL FACILITIES FOR A SINGLE LEVEL OF EDUCATION ON A SINGLE SITE, AND (4) ESTABLISHING RINGS OF SCHOOL PARKS ABOUT…

Error-Transparent Quantum Gates for Small Logical Qubit Architectures

NASA Astrophysics Data System (ADS)

Kapit, Eliot

2018-02-01

One of the largest obstacles to building a quantum computer is gate error, where the physical evolution of the state of a qubit or group of qubits during a gate operation does not match the intended unitary transformation. Gate error stems from a combination of control errors and random single qubit errors from interaction with the environment. While great strides have been made in mitigating control errors, intrinsic qubit error remains a serious problem that limits gate fidelity in modern qubit architectures. Simultaneously, recent developments of small error-corrected logical qubit devices promise significant increases in logical state lifetime, but translating those improvements into increases in gate fidelity is a complex challenge. In this Letter, we construct protocols for gates on and between small logical qubit devices which inherit the parent device's tolerance to single qubit errors which occur at any time before or during the gate. We consider two such devices, a passive implementation of the three-qubit bit flip code, and the author's own [E. Kapit, Phys. Rev. Lett. 116, 150501 (2016), 10.1103/PhysRevLett.116.150501] very small logical qubit (VSLQ) design, and propose error-tolerant gate sets for both. The effective logical gate error rate in these models displays superlinear error reduction with linear increases in single qubit lifetime, proving that passive error correction is capable of increasing gate fidelity. Using a standard phenomenological noise model for superconducting qubits, we demonstrate a realistic, universal one- and two-qubit gate set for the VSLQ, with error rates an order of magnitude lower than those for same-duration operations on single qubits or pairs of qubits. These developments further suggest that incorporating small logical qubits into a measurement based code could substantially improve code performance.

Single-neuron labeling with inducible cre-mediated knockout in transgenic mice

PubMed Central

Young, Paul; Qiu, Li; Wang, Dongqing; Zhao, Shengli; Gross, James; Feng, Guoping

2011-01-01

To facilitate functional analysis of neuronal connectivity in a mammalian nervous system tightly packed with billions of cells, we developed a new technique that allows inducible genetic manipulations within fluorescently labeled single neurons in mice. We term this technique SLICK for Single-neuron Labeling with Inducible Cre-mediated Knockout. SLICK is achieved by co-expressing a drug-inducible form of cre recombinase and a fluorescent protein within the same small subsets of neurons. Thus, SLICK combines the powerful cre recombinase system for conditional genetic manipulation and the fluorescent labeling of single neurons for imaging. We demonstrate efficient inducible genetic manipulation in several types of neurons using SLICK. Furthermore, we apply SLICK to eliminate synaptic transmission in a small subset of neuromuscular junctions. Our results provide evidence for the long-term stability of inactive neuromuscular synapses in adult animals. More broadly, these studies demonstrate a cre-LoxP compatible system for dissecting gene functions in single identifiable neurons. PMID:18454144

Improved Dye Stability in Single-Molecule Fluorescence Experiments

NASA Astrophysics Data System (ADS)

EcheverrÍa Aitken, Colin; Marshall, R. Andrew; Pugi, Joseph D.

Complex biological systems challenge existing single-molecule methods. In particular, dye stability limits observation time in singlemolecule fluorescence applications. Current approaches to improving dye performance involve the addition of enzymatic oxygen scavenging systems and small molecule additives. We present an enzymatic oxygen scavenging system that improves dye stability in single-molecule experiments. Compared to the currently-employed glucose-oxidase/catalase system, the protocatechuate-3,4-dioxygenase system achieves lower dissolved oxygen concentration and stabilizes single Cy3, Cy5, and Alexa488 fluorophores. Moreover, this system possesses none of the limitations associated with the glucose oxidase/catalase system. We also tested the effects of small molecule additives in this system. Biological reducing agents significantly destabilize the Cy5 fluorophore as a function of reducing potential. In contrast, anti-oxidants stabilize the Cy3 and Alexa488 fluorophores. We recommend use of the protocatechuate-3,4,-dioxygenase system with antioxidant additives, and in the absence of biological reducing agents. This system should have wide application to single-molecule fluorescence experiments.

Antigen Binding and Site-Directed Labeling of Biosilica-Immobilized Fusion Proteins Expressed in Diatoms

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

Ford, Nicole R.; Hecht, Karen A.; Hu, Dehong

2016-01-08

The diatom Thalassiosira pseudonana was genetically modified to express biosilica-targeted fusion proteins incorporating a tetracysteine tag for site-directed labeling with biarsenical affinity probes and either EGFP or single chain antibody to test colocalization of probes with the EGFP-tagged recombinant protein or binding of biosilica-immobilized antibodies to large and small molecule antigens, respectively. Site-directed labeling with the biarsenical probes demonstrated colocalization with EGFP-encoded proteins in nascent and mature biosilica, supporting their use in studying biosilica maturation. Isolated biosilica transformed with a single chain antibody against either the Bacillus anthracis surface layer protein EA1 or small molecule explosive trinitrotoluene (TNT) effectively boundmore » the respective antigens. A marked increase in fluorescence lifetime of the TNT surrogate Alexa Fluor 555-trinitrobenzene reflected the high binding specificity of the transformed isolated biosilica. These results demonstrated the potential use of biosilica-immobilized single chain antibodies as binders for large and small molecule antigens in sensing and therapeutics.« less

Microfluidics-based digital quantitative PCR for single-cell small RNA quantification.

PubMed

Yu, Tian; Tang, Chong; Zhang, Ying; Zhang, Ruirui; Yan, Wei

2017-09-01

Quantitative analyses of small RNAs at the single-cell level have been challenging because of limited sensitivity and specificity of conventional real-time quantitative PCR methods. A digital quantitative PCR (dqPCR) method for miRNA quantification has been developed, but it requires the use of proprietary stem-loop primers and only applies to miRNA quantification. Here, we report a microfluidics-based dqPCR (mdqPCR) method, which takes advantage of the Fluidigm BioMark HD system for both template partition and the subsequent high-throughput dqPCR. Our mdqPCR method demonstrated excellent sensitivity and reproducibility suitable for quantitative analyses of not only miRNAs but also all other small RNA species at the single-cell level. Using this method, we discovered that each sperm has a unique miRNA profile. © The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

SMALL ANGLE SCATTERING OF X-RAYS BY PLASTICALLY DEFORMED SINGLE CRYSTALS

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

Robinson, W.H.; Smoluchowski, R.

1959-05-01

The small-angle scattering of x rays from single crystals of magnesium plastically deformed by simple shear was measured in the angular range of 4' to 5 deg . The crystals were subjected to both unidirectional and cyclic shear stresses applied along the STAl 1 2-bar 0! direction. Thin slices of the deformed single crystals were prepared using strainfree cutting and polishing techniques. The thin slices had orientations such that the slip direction was either parallel or perpendicular to the incident x-ray beam in order to observe any anisotropy in the scattering that might be due to dislocations. It was foundmore » that those samples which contained deformation twins within the irradiated volume produced rather large scattered intensity. This scattered intensity is interpreted as being due to double Bragg scattering. The scattered intensity from other specimens was attributed to surface scattering. No evidence for small angle scattering by dislocations was found. (auth)« less

A new type of shotgun ammunition produces unique wound characteristics.

PubMed

Nelson, Craig L; Winston, David C

2007-01-01

The Tucson Police Department, Tucson, AZ, has begun using the Polyshok Impact Reactive Projectile (IRP), a new type of shotgun ammunition that includes a lead bead core that travels within single, plastic-encased projectile. On impact, the core is released to distribute over a small area, thereby disintegrating on impact to reduce the likelihood of exit or collateral damage on missed shots. After a brief review of shotgun slug ballistics and wound characteristics and a discussion of the mechanism of the Polyshok IRP, we report the first death in the United States from this ammunition. Findings included a single entrance wound with plastic ammunition components and small lead particles recovered from the body, the combination of which normally would suggest a close-range shooting with birdshot. However, the characteristics of this ammunition create different patterns than are found with slugs or shot, so that a medical examiner unfamiliar with the Polyshok IRP could draw inaccurate conclusions about ammunition and range of fire. Because the single projectile fired from this ammunition is composed of both plastic and lead, plastic components are likely to be found within the wound at any range of fire, unlike traditional shot or slug ammunition. Also, the small size of lead particles found spread through the wound cavity would ordinarily suggest a small-size shot, whereas the external appearance of the wound (a single entrance with no dispersion of shot) and the pattern of tissue destruction are more consistent with the patterns of injury associated with shotgun slugs.

Multiple Small Diameter Drillings Increase Femoral Neck Stability Compared with Single Large Diameter Femoral Head Core Decompression Technique for Avascular Necrosis of the Femoral Head.

PubMed

Brown, Philip J; Mannava, Sandeep; Seyler, Thorsten M; Plate, Johannes F; Van Sikes, Charles; Stitzel, Joel D; Lang, Jason E

2016-10-26

Femoral head core decompression is an efficacious joint-preserving procedure for treatment of early stage avascular necrosis. However, postoperative fractures have been described which may be related to the decompression technique used. Femoral head decompressions were performed on 12 matched human cadaveric femora comparing large 8mm single bore versus multiple 3mm small drilling techniques. Ultimate failure strength of the femora was tested using a servo-hydraulic material testing system. Ultimate load to failure was compared between the different decompression techniques using two paired ANCOVA linear regression models. Prior to biomechanical testing and after the intervention, volumetric bone mineral density was determined using quantitative computed tomography to account for variation between cadaveric samples and to assess the amount of bone disruption by the core decompression. Core decompression, using the small diameter bore and multiple drilling technique, withstood significantly greater load prior to failure compared with the single large bore technique after adjustment for bone mineral density (p< 0.05). The 8mm single bore technique removed a significantly larger volume of bone compared to the 3mm multiple drilling technique (p< 0.001). However, total fracture energy was similar between the two core decompression techniques. When considering core decompression for the treatment of early stage avascular necrosis, the multiple small bore technique removed less bone volume, thereby potentially leading to higher load to failure.

Single-stage surgery for symptomatic small-angle strabismus under topical anaesthesia.

PubMed

Zou, Leilei; Liu, Rui; Liu, Hong; Huang, Liwen; Liu, Yan; Wang, Aihou

2014-04-01

To report outcomes of single-stage surgery under topical anaesthesia for the treatment of small-angle strabismus. Case series. Thirteen patients, 7 males and 6 females, with a median age of 32 years (range, 20-59 years) were included. Patients with symptomatic small-angle strabismus with stable deviations of no more than 20 prism diopters (PD) in horizontal and 10 PD in vertical were consecutively recruited from the Eye and ENT Hospital of Fudan University between January 2010 and April 2012. Single-stage surgery was performed under topical anaesthesia. Outcome measures were PD, Amblyopia and Strabismus Questionnaire (ASQE) scores, and subjective reduction of symptoms. The median duration of symptoms was 40 months (range, 6-96 months). Nine patients had horizontal deviations, 3 had vertical deviations, and 1 had an exodeviation combined with a vertical deviation. All surgeries were completed without complications, and no patients experienced significant discomfort. All patients reported elimination of symptoms on postoperative day 1. Two patients required a second procedure at 1 week because of a return of symptoms. At 6-month follow-up, no patient reported recurrence of symptoms. The overall ASQE score improved from 70 preoperatively to 96 postoperatively (p = 0.001). These results suggest single-stage surgery under topical anaesthesia is an effective treatment for small-angle strabismus. A large, randomized, prospective study to confirm these findings is warranted. © 2013 Canadian Ophthalmological Society Published by Canadian Ophthalmological Society All rights reserved.

Local small airway epithelial injury induces global smooth muscle contraction and airway constriction

PubMed Central

Zhou, Jian; Alvarez-Elizondo, Martha B.; Botvinick, Elliot

2012-01-01

Small airway epithelial cells form a continuous sheet lining the conducting airways, which serves many functions including a physical barrier to protect the underlying tissue. In asthma, injury to epithelial cells can occur during bronchoconstriction, which may exacerbate airway hyperreactivity. To investigate the role of epithelial cell rupture in airway constriction, laser ablation was used to precisely rupture individual airway epithelial cells of small airways (<300-μm diameter) in rat lung slices (∼250-μm thick). Laser ablation of single epithelial cells using a femtosecond laser reproducibly induced airway contraction to ∼70% of the original cross-sectional area within several seconds, and the contraction lasted for up to 40 s. The airway constriction could be mimicked by mechanical rupture of a single epithelial cell using a sharp glass micropipette but not with a blunt glass pipette. These results suggest that soluble mediators released from the wounded epithelial cell induce global airway contraction. To confirm this hypothesis, the lysate of primary human small airway epithelial cells stimulated a similar airway contraction. Laser ablation of single epithelial cells triggered a single instantaneous Ca2+ wave in the epithelium, and multiple Ca2+ waves in smooth muscle cells, which were delayed by several seconds. Removal of extracellular Ca2+ or decreasing intracellular Ca2+ both blocked laser-induced airway contraction. We conclude that local epithelial cell rupture induces rapid and global airway constriction through release of soluble mediators and subsequent Ca2+-dependent smooth muscle shortening. PMID:22114176

Local small airway epithelial injury induces global smooth muscle contraction and airway constriction.

PubMed

Zhou, Jian; Alvarez-Elizondo, Martha B; Botvinick, Elliot; George, Steven C

2012-02-01

Small airway epithelial cells form a continuous sheet lining the conducting airways, which serves many functions including a physical barrier to protect the underlying tissue. In asthma, injury to epithelial cells can occur during bronchoconstriction, which may exacerbate airway hyperreactivity. To investigate the role of epithelial cell rupture in airway constriction, laser ablation was used to precisely rupture individual airway epithelial cells of small airways (<300-μm diameter) in rat lung slices (∼250-μm thick). Laser ablation of single epithelial cells using a femtosecond laser reproducibly induced airway contraction to ∼70% of the original cross-sectional area within several seconds, and the contraction lasted for up to 40 s. The airway constriction could be mimicked by mechanical rupture of a single epithelial cell using a sharp glass micropipette but not with a blunt glass pipette. These results suggest that soluble mediators released from the wounded epithelial cell induce global airway contraction. To confirm this hypothesis, the lysate of primary human small airway epithelial cells stimulated a similar airway contraction. Laser ablation of single epithelial cells triggered a single instantaneous Ca(2+) wave in the epithelium, and multiple Ca(2+) waves in smooth muscle cells, which were delayed by several seconds. Removal of extracellular Ca(2+) or decreasing intracellular Ca(2+) both blocked laser-induced airway contraction. We conclude that local epithelial cell rupture induces rapid and global airway constriction through release of soluble mediators and subsequent Ca(2+)-dependent smooth muscle shortening.

Phase 1 Study of CK-301 as a Single Agent in Subjects With Advanced Cancers

ClinicalTrials.gov

2018-01-02

Lung Neoplasms; Carcinoma, Non-Small-Cell Lung; Carcinoma, Small Cell; Malignant Mesothelioma, Advanced; Head and Neck Cancer; Melanoma; Merkel Cell Carcinoma; Renal Cell Carcinoma; Urothelial Carcinoma; Classical Hodgkin Lymphoma

Full Body Loading for Small Exercise Devices Project

NASA Technical Reports Server (NTRS)

Downs, Meghan; Hanson, Andrea; Newby, Nathaniel

2015-01-01

Protecting astronauts' spine, hip, and lower body musculoskeletal strength will be critical to safely and efficiently perform physically demanding vehicle egress, exploration, and habitat building activities necessary to expand human presence in the solar system. Functionally limiting decrements in musculoskeletal health are likely during Mars proving-ground and Earth-independent missions given extended transit times and the vehicle limitations for exercise devices (low-mass, small volume). Most small exercise device concepts are designed with single-cable loading, which inhibits the ability to perform full body exercises requiring two-point loading at the shoulders. Shoulder loading is critical to protect spine, hip, and lower body musculoskeletal strength. We propose a novel low-mass, low-maintenance, and rapid deploy pulley-based system that can attach to a single-cable small exercise device to enable two-point loading at the shoulders. This attachment could protect astronauts' health and save cost, space, and energy during all phases of the Journey to Mars.

A Small and Slim Coaxial Probe for Single Rice Grain Moisture Sensing

PubMed Central

You, Kok Yeow; Mun, Hou Kit; You, Li Ling; Salleh, Jamaliah; Abbas, Zulkifly

2013-01-01

A moisture detection of single rice grains using a slim and small open-ended coaxial probe is presented. The coaxial probe is suitable for the nondestructive measurement of moisture values in the rice grains ranging from from 9.5% to 26%. Empirical polynomial models are developed to predict the gravimetric moisture content of rice based on measured reflection coefficients using a vector network analyzer. The relationship between the reflection coefficient and relative permittivity were also created using a regression method and expressed in a polynomial model, whose model coefficients were obtained by fitting the data from Finite Element-based simulation. Besides, the designed single rice grain sample holder and experimental set-up were shown. The measurement of single rice grains in this study is more precise compared to the measurement in conventional bulk rice grains, as the random air gap present in the bulk rice grains is excluded. PMID:23493127

Very Low Abundance Single-Cell Transcript Quantification with 5-Plex ddPCRTM Assays.

PubMed

Karlin-Neumann, George; Zhang, Bin; Litterst, Claudia

2018-01-01

Gene expression studies have provided one of the most accessible windows for understanding the molecular basis of cell and tissue phenotypes and how these change in response to stimuli. Current PCR-based and next generation sequencing methods offer great versatility in allowing the focused study of the roles of small numbers of genes or comprehensive profiling of the entire transcriptome of a sample at one time. Marrying of these approaches to various cell sorting technologies has recently enabled the profiling of expression in single cells, thereby increasing the resolution and sensitivity and strengthening the inferences from observed expression levels and changes. This chapter presents a quick and efficient 1-day workflow for sorting single cells with a small laboratory cell-sorter followed by an ultrahigh sensitivity, multiplexed digital PCR method for quantitative tracking of changes in 5-10 genes per single cell.

X-ray remote sensing and in-situ spectroscopy for planetary exploration missions and gamma-ray remote sensing and in-situ spectroscopy for planetary exploration missions

NASA Technical Reports Server (NTRS)

Mahdavi, M.; Giboni, K. L.; Vajda, S.; Schweitzer, J.

1994-01-01

Detectors that will be used for planetary missions must have their responses calibrated in a reproducible manner. A calibration facility is being constructed at Schlumberger-Doll Research for gamma and x ray detectors. With this facility the detector response can be determined in an invariant and reproducible fashion. Initial use of the facility is expected for the MARS94 detectors. Work is continuing to better understand the rare earth oxyorthosilicates and to define their characteristics. This will allow a better use of these scintillators for planetary missions. In a survey of scintillating materials two scintillators were identified as promising candidates besides GSO, LSO, and YSO. These are CdWO4 and CsI(Tl). It will be investigated if a detector with a better overall performance can be assembled with various photon converters. Considerable progress was achieved in photomultiplier design. The length of an 1 inch diameter PMT could be reduced from 4.2 to 2.5 inches without performance degradation. This technology is being employed in the gamma ray detector for the NEAR project. A further weight and size reduction of the detector package can be achieved with miniaturized integrated power supplies.

MODELING TIME DISPERSION DUE TO OPTICAL PATH LENGTH DIFFERENCES IN SCINTILLATION DETECTORS*

PubMed Central

Moses, W.W.; Choong, W.-S.; Derenzo, S.E.

2015-01-01

We characterize the nature of the time dispersion in scintillation detectors caused by path length differences of the scintillation photons as they travel from their generation point to the photodetector. Using Monte Carlo simulation, we find that the initial portion of the distribution (which is the only portion that affects the timing resolution) can usually be modeled by an exponential decay. The peak amplitude and decay time depend both on the geometry of the crystal, the position within the crystal that the scintillation light originates from, and the surface finish. In a rectangular parallelpiped LSO crystal with 3 mm × 3 mm cross section and polished surfaces, the decay time ranges from 10 ps (for interactions 1 mm from the photodetector) up to 80 ps (for interactions 50 mm from the photodetector). Over that same range of distances, the peak amplitude ranges from 100% (defined as the peak amplitude for interactions 1 mm from the photodetector) down to 4% for interactions 50 mm from the photodetector. Higher values for the decay time are obtained for rough surfaces, but the exact value depends on the simulation details. Estimates for the decay time and peak amplitude can be made for different cross section sizes via simple scaling arguments. PMID:25729464

Modeling Time Dispersion Due to Optical Path Length Differences in Scintillation Detectors

DOE PAGES

Moses, W. W.; Choong, W. -S.; Derenzo, S. E.

2014-08-20

In this paper, we characterize the nature of the time dispersion in scintillation detectors caused by path length differences of the scintillation photons as they travel from their generation point to the photodetector. Using Monte Carlo simulation, we find that the initial portion of the distribution (which is the only portion that affects the timing resolution) can usually be modeled by an exponential decay. The peak amplitude and decay time depend both on the geometry of the crystal, the position within the crystal that the scintillation light originates from, and the surface finish. In a rectangular parallelpiped LSO crystal withmore » 3 mm × 3 mm cross section and polished surfaces, the decay time ranges from 10 ps (for interactions 1 mm from the photodetector) up to 80 ps (for interactions 50 mm from the photodetector). Over that same range of distances, the peak amplitude ranges from 100% (defined as the peak amplitude for interactions 1 mm from the photodetector) down to 4% for interactions 50 mm from the photodetector. Higher values for the decay time are obtained for rough surfaces, but the exact value depends on the simulation details. Finally, estimates for the decay time and peak amplitude can be made for different cross section sizes via simple scaling arguments.« less

[Position paper from the Department of Ethics of the Chilean College of Physicians about conscientious objection].

PubMed

Salas, Sofía P; Besio, Mauricio; Bórquez Estefó, Gladys; Salinas, Rodrigo A; Valenzuela, Carlos Y; Micolich, Constanza; Novoa Sotta, Fernando; Bernier Villarroel, Lioniel; Montt M, Julio; Misseroni Raddatz, Adelio

2016-03-01

The Chilean bill that regulates abortion for three cases (Bulletin Nº 9895-11) includes the possibility that health professionals may manifest their conscientious objection (CO) to perform this procedure. Due to the broad impact that the issue of C O had, the Ethics Department of the Chilean College of Physicians considered important to review this concept and its ethical and legal basis, especially in the field of sexual and reproductive health. In the present document, we define the practical limit s of CO, both for the proper fulfillment of the medical profession obligations, and for the due respect and non-discrimination that the professional objector deserves. We analyze the denial of some health institutions to perform abortions if it is legalize d, and we end with recommendations adjusted to the Chilean reality. Specifically, we recognize the right to conscientious objection that all physicians who directly participate in a professional act have. But we a lso recognize that physicians have ineludib le obligations towards their patients, including the obligation to inform about the existence of this service, how to access to it and -as set out in our code of ethics- to ensure that another colleague will continue attending the patient.

First characterization of a digital SiPM based time-of-flight PET detector with 1 mm spatial resolution

NASA Astrophysics Data System (ADS)

Seifert, Stefan; van der Lei, Gerben; van Dam, Herman T.; Schaart, Dennis R.

2013-05-01

Monolithic scintillator detectors can offer a combination of spatial resolution, energy resolution, timing performance, depth-of-interaction information, and detection efficiency that make this type of detector a promising candidate for application in clinical, time-of-flight (TOF) positron emission tomography (PET). In such detectors the scintillation light is distributed over a relatively large number of photosensor pixels and the light intensity per pixel can be relatively low. Therefore, monolithic scintillator detectors are expected to benefit from the low readout noise offered by a novel photosensor called the digital silicon photomultiplier (dSiPM). Here, we present a first experimental characterization of a TOF PET detector comprising a 24 × 24 × 10 mm3 LSO:Ce,0.2%Ca scintillator read out by a dSiPM array (DPC-6400-44-22) developed by Philips Digital Photon Counting. A spatial resolution of ˜1 mm full-width-at-half-maximum (FWHM) averaged over the entire crystal was obtained (varying from just below 1 mm FWHM in the detector center to ˜1.2 mm FWHM close to the edges). Furthermore, the bias in the position estimation at the crystal edges that is typically found in monolithic scintillators is well below 1 mm even in the corners of the crystal.

Group specific internal standard technology (GSIST) for simultaneous identification and quantification of small molecules

DOEpatents

Adamec, Jiri; Yang, Wen-Chu; Regnier, Fred E

2014-01-14

Reagents and methods are provided that permit simultaneous analysis of multiple diverse small molecule analytes present in a complex mixture. Samples are labeled with chemically identical but isotopically distince forms of the labeling reagent, and analyzed using mass spectrometry. A single reagent simultaneously derivatizes multiple small molecule analytes having different reactive functional groups.

Modified floating-zone growth of organic single crystals

NASA Astrophysics Data System (ADS)

Kou, S.; Chen, C. P.

1994-04-01

For organic materials floating-zone crystal growth is superior to other melt growth processes in two significant respects: (1) the absence of crucible-induced mechanical damage and (2) minimum heating-induced chemical degradation. Due to the rather low surface tension of organic melts, however, floating-zone crystal growth under normal gravity has not been possible so far but microgravity is ideal for such a purpose. With the help of a modified floating-zone technique, organic single crystals of small cross-sections were test grown first under normal gravity. These small crystals were round and rectangular single crystals of benzil and salol, up to about 7 cm long and 6 mm in diameter or 9 mm × 3 mm in cross-section.

Single Mothers, the Underclass, and Social Policy. CDE Working Paper 88-30.

ERIC Educational Resources Information Center

McLanahan, Sara; Garfinkel, Irv

Although the vast majority of single mothers do not fit the description of an underclass, there is a small group of predominantly black single mothers concentrated in northern urban ghettos that is persistently weakly attached to the labor force, socially isolated, and reproducing itself. Although welfare programs are necessary for those who are…

Twelve- to 14-Month-Old Infants Can Predict Single-Event Probability with Large Set Sizes

ERIC Educational Resources Information Center

Denison, Stephanie; Xu, Fei

2010-01-01

Previous research has revealed that infants can reason correctly about single-event probabilities with small but not large set sizes (Bonatti, 2008; Teglas "et al.", 2007). The current study asks whether infants can make predictions regarding single-event probability with large set sizes using a novel procedure. Infants completed two trials: A…

Crash testing of Louisiana's multi-directional, single steel post, small sign support.

DOT National Transportation Integrated Search

1992-06-01

The Louisiana Department of Transportation and Development (LDOTD) contracted with the Texas Transportation Institute (TTI) to evaluate the impact characteristics of Louisiana's multi-directional 5 inch diameter steel post, small sign support when im...

Mass action at the single-molecule level.

PubMed

Shon, Min Ju; Cohen, Adam E

2012-09-05

We developed a system to reversibly encapsulate small numbers of molecules in an array of nanofabricated "dimples". This system enables highly parallel, long-term, and attachment-free studies of molecular dynamics via single-molecule fluorescence. In studies of bimolecular reactions of small numbers of confined molecules, we see phenomena that, while expected from basic statistical mechanics, are not observed in bulk chemistry. Statistical fluctuations in the occupancy of sealed reaction chambers lead to steady-state fluctuations in reaction equilibria and rates. These phenomena are likely to be important whenever reactions happen in confined geometries.

Very Long Single and Few-Walled Boron Nitride Nanotubes via the Pressurized Vapor/Condenser Method

NASA Technical Reports Server (NTRS)

Smith, Michael W.; Jordan, Kevin C.; Park, Cheol; Kim, Jae-Woo; Lillehei, Peter T.; Crooks, Roy; Harrison, Joycelyn S.

2009-01-01

A new method for producing long, small diameter, single and few-walled, boron nitride nanotubes (BNNTs) in macroscopic quantities is reported. The pressurized vapor/condenser (PVC) method produces, without catalysts, highly crystalline, very long, small diameter, BNNTs. Palm-sized, cotton-like masses of BNNT raw material were grown by this technique and spun directly into centimeters-long yarn. Nanotube lengths were observed to be 100 times that of those grown by the most closely related method. Self-assembly and growth models for these long BNNTs are discussed.

James Webb Space Telescope segment phasing using differential optical transfer functions

PubMed Central

Codona, Johanan L.; Doble, Nathan

2015-01-01

Differential optical transfer function (dOTF) is an image-based, noniterative wavefront sensing method that uses two star images with a single small change in the pupil. We describe two possible methods for introducing the required pupil modification to the James Webb Space Telescope, one using a small (<λ/4) displacement of a single segment's actuator and another that uses small misalignments of the NIRCam's filter wheel. While both methods should work with NIRCam, the actuator method will allow both MIRI and NIRISS to be used for segment phasing, which is a new functionality. Since the actuator method requires only small displacements, it should provide a fast and safe phasing alternative that reduces the mission risk and can be performed frequently for alignment monitoring and maintenance. Since a single actuator modification can be seen by all three cameras, it should be possible to calibrate the non-common-path aberrations between them. Large segment discontinuities can be measured using dOTFs in two filter bands. Using two images of a star field, aberrations along multiple lines of sight through the telescope can be measured simultaneously. Also, since dOTF gives the pupil field amplitude as well as the phase, it could provide a first approximation or constraint to the planned iterative phase retrieval algorithms. PMID:27042684

A fluid membrane enhances the velocity of cargo transport by small teams of kinesin-1

NASA Astrophysics Data System (ADS)

Li, Qiaochu; Tseng, Kuo-Fu; King, Stephen J.; Qiu, Weihong; Xu, Jing

2018-03-01

Kinesin-1 (hereafter referred to as kinesin) is a major microtubule-based motor protein for plus-end-directed intracellular transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized "motile fraction" to overcome this challenge and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro and employed optical trapping to quantify the transport of membrane-enclosed cargos versus traditional membrane-free cargos under identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins. Importantly, enclosing a cargo in a fluid lipid membrane did not impact single-kinesin transport, indicating that membrane-dependent velocity enhancement for team-based transport arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for fast delivery of cargos in live cells.

Diversity of human small intestinal Streptococcus and Veillonella populations.

PubMed

van den Bogert, Bartholomeus; Erkus, Oylum; Boekhorst, Jos; de Goffau, Marcus; Smid, Eddy J; Zoetendal, Erwin G; Kleerebezem, Michiel

2013-08-01

Molecular and cultivation approaches were employed to study the phylogenetic richness and temporal dynamics of Streptococcus and Veillonella populations in the small intestine. Microbial profiling of human small intestinal samples collected from four ileostomy subjects at four time points displayed abundant populations of Streptococcus spp. most affiliated with S. salivarius, S. thermophilus, and S. parasanguinis, as well as Veillonella spp. affiliated with V. atypica, V. parvula, V. dispar, and V. rogosae. Relative abundances varied per subject and time of sampling. Streptococcus and Veillonella isolates were cultured using selective media from ileostoma effluent samples collected at two time points from a single subject. The richness of the Streptococcus and Veillonella isolates was assessed at species and strain level by 16S rRNA gene sequencing and genetic fingerprinting, respectively. A total of 160 Streptococcus and 37 Veillonella isolates were obtained. Genetic fingerprinting differentiated seven Streptococcus lineages from ileostoma effluent, illustrating the strain richness within this ecosystem. The Veillonella isolates were represented by a single phylotype. Our study demonstrated that the small intestinal Streptococcus populations displayed considerable changes over time at the genetic lineage level because only representative strains of a single Streptococcus lineage could be cultivated from ileostoma effluent at both time points. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Describing an Environment for a Self-Sustaining Technology Transfer Service in a Small Research Budget University: A Case Study

ERIC Educational Resources Information Center

Nieb, Sharon Lynn

2014-01-01

This single-site qualitative study sought to identify the characteristics that contribute to the self sustainability of technology transfer services at universities with small research budgets through a case study analysis of a small research budget university that has been operating a financially self-sustainable technology transfer service for…

Saha equation, single and two particle states

NASA Technical Reports Server (NTRS)

Kraeft, W. D.; Girardeau, M. D.; Strege, B.

1990-01-01

Single- and two-particle properties in a dense plasma are discussed in connection with their role in the mass action law for a partially ionized plasma. The two-particle-bound states are nearly density independent, while the continuum is essentially shifted. The single-particle states are damped, and their energy has a negative shift and a parabolic behavior for small momenta.

Coil planet centrifugation as a means for small particle separation

NASA Technical Reports Server (NTRS)

Herrmann, F. T.

1983-01-01

The coil planet centrifuge uses a centrifugal force field to provide separation of particles based on differences in sedimentation rates by flow through a rotating coiled tube. Three main separations are considered: (1) single phase fresh sheep and human erythrocytes, (2) single phase fixed heep and human erythrocytes, and (3) electrophoretically enhanced single phase fresh sheep and human erythrocytes.

Facilities for small-molecule crystallography at synchrotron sources.

PubMed

Barnett, Sarah A; Nowell, Harriott; Warren, Mark R; Wilcox, Andrian; Allan, David R

2016-01-01

Although macromolecular crystallography is a widely supported technique at synchrotron radiation facilities throughout the world, there are, in comparison, only very few beamlines dedicated to small-molecule crystallography. This limited provision is despite the increasing demand for beamtime from the chemical crystallography community and the ever greater overlap between systems that can be classed as either small macromolecules or large small molecules. In this article, a very brief overview of beamlines that support small-molecule single-crystal diffraction techniques will be given along with a more detailed description of beamline I19, a dedicated facility for small-molecule crystallography at Diamond Light Source.

Feature-fused SSD: fast detection for small objects

NASA Astrophysics Data System (ADS)

Cao, Guimei; Xie, Xuemei; Yang, Wenzhe; Liao, Quan; Shi, Guangming; Wu, Jinjian

2018-04-01

Small objects detection is a challenging task in computer vision due to its limited resolution and information. In order to solve this problem, the majority of existing methods sacrifice speed for improvement in accuracy. In this paper, we aim to detect small objects at a fast speed, using the best object detector Single Shot Multibox Detector (SSD) with respect to accuracy-vs-speed trade-off as base architecture. We propose a multi-level feature fusion method for introducing contextual information in SSD, in order to improve the accuracy for small objects. In detailed fusion operation, we design two feature fusion modules, concatenation module and element-sum module, different in the way of adding contextual information. Experimental results show that these two fusion modules obtain higher mAP on PASCAL VOC2007 than baseline SSD by 1.6 and 1.7 points respectively, especially with 2-3 points improvement on some small objects categories. The testing speed of them is 43 and 40 FPS respectively, superior to the state of the art Deconvolutional single shot detector (DSSD) by 29.4 and 26.4 FPS.

Silicon photon-counting avalanche diodes for single-molecule fluorescence spectroscopy

PubMed Central

Michalet, Xavier; Ingargiola, Antonino; Colyer, Ryan A.; Scalia, Giuseppe; Weiss, Shimon; Maccagnani, Piera; Gulinatti, Angelo; Rech, Ivan; Ghioni, Massimo

2014-01-01

Solution-based single-molecule fluorescence spectroscopy is a powerful experimental tool with applications in cell biology, biochemistry and biophysics. The basic feature of this technique is to excite and collect light from a very small volume and work in a low concentration regime resulting in rare burst-like events corresponding to the transit of a single molecule. Detecting photon bursts is a challenging task: the small number of emitted photons in each burst calls for high detector sensitivity. Bursts are very brief, requiring detectors with fast response time and capable of sustaining high count rates. Finally, many bursts need to be accumulated to achieve proper statistical accuracy, resulting in long measurement time unless parallelization strategies are implemented to speed up data acquisition. In this paper we will show that silicon single-photon avalanche diodes (SPADs) best meet the needs of single-molecule detection. We will review the key SPAD parameters and highlight the issues to be addressed in their design, fabrication and operation. After surveying the state-of-the-art SPAD technologies, we will describe our recent progress towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. The potential of this approach is illustrated with single-molecule Förster resonance energy transfer measurements. PMID:25309114

Novel Materials Containing Single-Wall Carbon Nanotubes Wrapped in Polymer Molecules

NASA Technical Reports Server (NTRS)

Smalley, Richard E.; O'Connell, Michael J.; Smith, Kenneth; Colbert, Daniel T.

2009-01-01

In this design, single-wall carbon nanotubes (SWNTs) have been coated in polymer molecules to create a new type of material that has low electrical conductivity, but still contains individual nanotubes, and small ropes of individual nanotubes, which are themselves good electrical conductors and serve as small conducting rods immersed in an electrically insulating matrix. The polymer is attached through weak chemical forces that are primarily non-covalent in nature, caused primarily through polarization rather than the sharing of valence electrons. Therefore, the electronic structure of the SWNT involved is substantially the same as that of free, individual (and small ropes of) SWNT. Their high conductivity makes the individual nanotubes extremely electrically polarizable, and materials containing these individual, highly polarizable molecules exhibit novel electrical properties including a high dielectric constant.

Solution-processed small-molecule solar cells: breaking the 10% power conversion efficiency.

PubMed

Liu, Yongsheng; Chen, Chun-Chao; Hong, Ziruo; Gao, Jing; Yang, Yang Michael; Zhou, Huanping; Dou, Letian; Li, Gang; Yang, Yang

2013-11-28

A two-dimensional conjugated small molecule (SMPV1) was designed and synthesized for high performance solution-processed organic solar cells. This study explores the photovoltaic properties of this molecule as a donor, with a fullerene derivative as an acceptor, using solution processing in single junction and double junction tandem solar cells. The single junction solar cells based on SMPV1 exhibited a certified power conversion efficiency of 8.02% under AM 1.5 G irradiation (100 mW cm(-2)). A homo-tandem solar cell based on SMPV1 was constructed with a novel interlayer (or tunnel junction) consisting of bilayer conjugated polyelectrolyte, demonstrating an unprecedented PCE of 10.1%. These results strongly suggest solution-processed small molecular materials are excellent candidates for organic solar cells.

A simple, fast, and inexpensive CTAB-PVP-silica based method for genomic DNA isolation from single, small insect larvae and pupae.

PubMed

Huanca-Mamani, W; Rivera-Cabello, D; Maita-Maita, J

2015-07-17

In this study, we report a modified CTAB-PVP method combined with silicon dioxide (silica) treatment for the extraction of high quality genomic DNA from a single larva or pupa. This method efficiently obtains DNA from small specimens, which is difficult and challenging because of the small amount of starting tissue. Maceration with liquid nitrogen, phenol treatment, and the ethanol precipitation step are eliminated using this methodology. The A260/A280 absorbance ratios of the isolated DNA were approximately 1.8, suggesting that the DNA is pure and can be used for further molecular analysis. The quality of the isolated DNA permits molecular applications and represents a fast, cheap, and effective alternative method for laboratories with low budgets.

Analysis of long-time operation of micro-cogeneration unit with fuel cell

NASA Astrophysics Data System (ADS)

Patsch, Marek; Čaja, Alexander

2015-05-01

Micro-cogeneration is cogeneration with small performance, with maximal electric power up to 50 kWe. On the present, there are available small micro-cogeneration units with small electric performance, about 1 kWe, which are usable also in single family houses or flats. These micro-cogeneration units operate on principle of conventional combustion engine, Stirling engine, steam engine or fuel cell. Micro-cogeneration units with fuel cells are new progressive developing type of units for single family houses. Fuel cell is electrochemical device which by oxidation-reduction reaction turn directly chemical energy of fuel to electric power, secondary products are pure water and thermal energy. The aim of paper is measuring and evaluation of operation parameters of micro-cogeneration unit with fuel cell which uses natural gas as a fuel.

Small FDIRC designs

DOE PAGES

Dey, B.; Ratcliff, B.; Va’vra, J.

2017-02-16

In this article, we explore the angular resolution limits attainable in small FDIRC designs taking advantage of the new highly pixelated detectors that are now available. Since the basic FDIRC design concept attains its particle separation performance mostly in the angular domain as measured by two-dimensional pixels, this paper relies primarily on a pixel-based analysis, with additional chromatic corrections using the time domain, requiring single photon timing resolution at a level of 100–200 ps only. This approach differs from other modern DIRC design concepts such as TOP or TORCH detectors, whose separation performances rely more strongly on time-dependent analyses. Inmore » conclusion, we find excellent single photon resolution with a geometry where individual bars are coupled to a single plate, which is coupled in turn to a cylindrical lens focusing camera.« less

Small FDIRC designs

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

Dey, B.; Ratcliff, B.; Va’vra, J.

In this article, we explore the angular resolution limits attainable in small FDIRC designs taking advantage of the new highly pixelated detectors that are now available. Since the basic FDIRC design concept attains its particle separation performance mostly in the angular domain as measured by two-dimensional pixels, this paper relies primarily on a pixel-based analysis, with additional chromatic corrections using the time domain, requiring single photon timing resolution at a level of 100–200 ps only. This approach differs from other modern DIRC design concepts such as TOP or TORCH detectors, whose separation performances rely more strongly on time-dependent analyses. Inmore » conclusion, we find excellent single photon resolution with a geometry where individual bars are coupled to a single plate, which is coupled in turn to a cylindrical lens focusing camera.« less

Backscattering from a randomly rough dielectric surface

NASA Technical Reports Server (NTRS)

Fung, Adrian K.; Li, Zongqian; Chen, K. S.

1992-01-01

A backscattering model for scattering from a randomly rough dielectric surface is developed based on an approximate solution of a pair of integral equations for the tangential surface fields. Both like and cross-polarized scattering coefficients are obtained. It is found that the like polarized scattering coefficients contain two types of terms: single scattering terms and multiple scattering terms. The single scattering terms in like polarized scattering are shown to reduce the first-order solutions derived from the small perturbation method when the roughness parameters satisfy the slightly rough conditions. When surface roughnesses are large but the surface slope is small, only a single scattering term corresponding to the standard Kirchhoff model is significant. If the surface slope is large, the multiple scattering term will also be significant. The cross-polarized backscattering coefficients satisfy reciprocity and contain only multiple scattering terms. The difference between vertical and horizontal scattering coefficients is found to increase with the dielectric constant and is generally smaller than that predicted by the first-order small perturbation model. Good agreements are obtained between this model and measurements from statistically known surfaces.

Sequence Analysis and Domain Motifs in the Porcine Skin Decorin Glycosaminoglycan Chain*

PubMed Central

Zhao, Xue; Yang, Bo; Solakylidirim, Kemal; Joo, Eun Ji; Toida, Toshihiko; Higashi, Kyohei; Linhardt, Robert J.; Li, Lingyun

2013-01-01

Decorin proteoglycan is comprised of a core protein containing a single O-linked dermatan sulfate/chondroitin sulfate glycosaminoglycan (GAG) chain. Although the sequence of the decorin core protein is determined by the gene encoding its structure, the structure of its GAG chain is determined in the Golgi. The recent application of modern MS to bikunin, a far simpler chondroitin sulfate proteoglycans, suggests that it has a single or small number of defined sequences. On this basis, a similar approach to sequence the decorin of porcine skin much larger and more structurally complex dermatan sulfate/chondroitin sulfate GAG chain was undertaken. This approach resulted in information on the consistency/variability of its linkage region at the reducing end of the GAG chain, its iduronic acid-rich domain, glucuronic acid-rich domain, and non-reducing end. A general motif for the porcine skin decorin GAG chain was established. A single small decorin GAG chain was sequenced using MS/MS analysis. The data obtained in the study suggest that the decorin GAG chain has a small or a limited number of sequences. PMID:23423381

A multilevel meta-analysis of single-case and small-n research on interventions for reducing challenging behavior in persons with intellectual disabilities.

PubMed

Heyvaert, M; Maes, B; Van den Noortgate, W; Kuppens, S; Onghena, P

2012-01-01

The effectiveness of different interventions for challenging behavior (CB) in persons with intellectual disabilities (ID) was reviewed by means of a two-phase study. First, a systematic review of 137 meta-analyses and reviews on group-study interventions for CB in persons with ID was conducted. Based on this review, hypotheses concerning the effectiveness of divergent interventions for CB and concerning the impact of variables moderating treatment effectiveness were systematically generated. Second, these hypotheses were tested by means of a multilevel meta-analysis of single-case and small-n research. Two hundred and eighty-five studies reporting on 598 individuals were examined. The average treatment effect was large and statistically significant. However, this effect varied significantly over the included studies and participants. Compared to the meta-analyses and reviews focusing on group-studies in this research domain, the results of the present multilevel meta-analysis of single-case and small-n intervention research provided more detailed knowledge on which specific CB and intervention components moderate the interventions' effectiveness. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ground Motion Uncertainty and Variability (single-station sigma): Insights from Euroseistest, Greece

NASA Astrophysics Data System (ADS)

Ktenidou, O. J.; Roumelioti, Z.; Abrahamson, N. A.; Cotton, F.; Pitilakis, K.

2014-12-01

Despite recent improvements in networks and data, the global aleatory uncertainty (sigma) in GMPEs is still large. One reason is the ergodic approach, where we combine data in space to make up for lack of data in time. By estimating the systematic site response, we can make site-specific GMPEs and use a lower, site-specific uncertainty: single-station sigma. In this study we use the EUROSEISTEST database (http://euroseisdb.civil.auth.gr), which has two distinct advantages: good existing knowledge of site conditions at all stations, and careful relocation of the recorded events. Constraining the site and source parameters as best we can, we minimise the within- and between-events components of the global, ergodic sigma. Following that, knowledge of the site response from empirical and theoretical approaches permits us to move on to single-station sigma. The variability per site is not clearly correlated to the site class. We show that in some cases knowledge of Vs30 is not sufficient, and that site-specific data are needed to capture the response, possibly due to 2D/3D effects from complex geometry. Our values of single-station sigma are low compared to the literature. This may be due to the good ray coverage we have in all directions for small, nearby records. Indeed, our single-station sigma values are similar to published single-path values, which means that they may correspond to a fully -rather than partially- non-ergodic approach. We find larger ground motion variability for short distances and small magnitudes. This may be related to the uncertainty in the depth affecting nearby records more, or to stress drop and causing trade-offs between the source and site terms for small magnitudes.

Stimulation of colonic motility by oral PEG electrolyte bowel preparation assessed by MRI: comparison of split vs single dose

PubMed Central

Marciani, L; Garsed, K C; Hoad, C L; Fields, A; Fordham, I; Pritchard, S E; Placidi, E; Murray, K; Chaddock, G; Costigan, C; Lam, C; Jalanka-Tuovinen, J; De Vos, W M; Gowland, P A; Spiller, R C

2014-01-01

Background Most methods of assessing colonic motility are poorly acceptable to patients. Magnetic resonance imaging (MRI) can monitor gastrointestinal motility and fluid distributions. We predicted that a dose of oral polyethylene glycol (PEG) and electrolyte solution would increase ileo-colonic inflow and stimulate colonic motility. We aimed to investigate the colonic response to distension by oral PEG electrolyte in healthy volunteers (HVs) and to evaluate the effect of single 2 L vs split (2 × 1 L) dosing. Methods Twelve HVs received a split dose (1 L the evening before and 1 L on the study day) and another 12 HVs a single dose (2 L on the main study day) of PEG electrolyte. They underwent MRI scans, completed symptom questionnaires, and provided stool samples. Outcomes included small bowel water content, ascending colon motility index, and regional colonic volumes. Key Results Small bowel water content increased fourfold from baseline after ingesting both split (p = 0.0010) and single dose (p = 0.0005). The total colonic volume increase from baseline was smaller for the split dose at 35 ± 8% than for the single dose at 102 ± 27%, p = 0.0332. The ascending colon motility index after treatment was twofold higher for the single dose group (p = 0.0103). Conclusions & Inferences Ingestion of 1 and 2 L PEG electrolyte solution caused a rapid increase in the small bowel and colonic volumes and a robust rise in colonic motility. The increase in both volumes and motility was dose dependent. Such a challenge, being well-tolerated, could be a useful way of assessing colonic motility in future studies. PMID:25060551

Small cell lung cancer presenting as dermatomyositis: mistaken for single connective tissue disease.

PubMed

Chao, Guanqun; Fang, Lizheng; Lu, Chongrong; Chen, Zhouwen

2012-06-01

Dermatomyositis (DM) is well-known to be associated with several types of malignancy. This case emphasizes the importance of a thorough examination for an underlying cancer, in patients with the symptoms of dermatomyositis. We report the case of a 62-year-old Chinese man who presented with a two-month history of edema of face and neck, together with erythema of the eyelids diagnosed of small cell lung cancer. Initially, it was thought to be single connective tissue disease such as DM. This study highlights the importance of a thorough physical examination when visiting a patient.

Analysis of the Laser Drilling Process for the Combination with a Single-Lip Deep Hole Drilling Process with Small Diameters

NASA Astrophysics Data System (ADS)

Biermann, Dirk; Heilmann, Markus

Due to the tendency of downsizing of components, also the industrial relevance of bore holes with small diameters and high length-to-diameter ratios rises with the growing requirements on parts. In these applications, the combination of laser pre-drilling and single-lip deep hole drilling can shorten the process chain in machining components with non-planar surfaces, or can reduce tool wear in machining case-hardened materials. In this research, the combination of these processes was realized and investigated for the very first time.

Safety Performance of Small Lithium-Ion Cells in High Voltage Batteries

NASA Technical Reports Server (NTRS)

Cowles, Philip R.; Darcy, Eric C.; Davies, Frank J.; Jeevarajan, Judith A.; Spurrett, Robert P.

2003-01-01

Topics covered include: Small-cell EAPU work done by NASA-JSC & COM DEV; Looking at safety features (short circuit protection - PTCs); Early tests showed that long strings do not withstand short circuit; a) Some PTCs experience large negative voltages; b) Destructive results. Solution: group cells into shorter substrings, with bypass diodes Work included: a) Tests with single cells shorted; b) Tests with single cells with imposed-negative voltages; c) 6s, 7s and 8s string shorts; and d) Tests with protection scheme in place, on 12s and 41s x 5p.

13 CFR 107.150 - Management-ownership diversity requirement.

Code of Federal Regulations, 2012 CFR

2012-01-01

... with any of your Associates. A single “acceptable” Institutional Investor may be substituted for two or... if exempt from Federal income taxation; and (vi) Other Institutional Investors satisfactory to SBA... requirement. 107.150 Section 107.150 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL...

13 CFR 107.150 - Management-ownership diversity requirement.

Code of Federal Regulations, 2014 CFR

2014-01-01

... with any of your Associates. A single “acceptable” Institutional Investor may be substituted for two or... if exempt from Federal income taxation; and (vi) Other Institutional Investors satisfactory to SBA... requirement. 107.150 Section 107.150 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL...

13 CFR 107.150 - Management-ownership diversity requirement.

Code of Federal Regulations, 2013 CFR

2013-01-01

... with any of your Associates. A single “acceptable” Institutional Investor may be substituted for two or... if exempt from Federal income taxation; and (vi) Other Institutional Investors satisfactory to SBA... requirement. 107.150 Section 107.150 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL...

A small intestine volvulus caused by strangulation of a mesenteric lipoma: a case report.

PubMed

Kakiuchi, Yoshihiko; Mashima, Hiroaki; Hori, Naoto; Takashima, Hirotoshi

2017-03-13

An emergency department encounters a variety of cases, including rare cases of the strangulation of a mesenteric lipoma by the greater omentum band. A 67-year-old Japanese man presented with nausea, vomiting, and upper abdominal pain. There were no abnormalities detected by routine blood tests other than a slight rise in his white cell count. A contrast-enhanced computed tomography scan of his abdomen revealed a dilated intestine, a small intestine volvulus, and a well-capsulated homogeneous mass. He was suspected of having a small intestine volvulus that was affected by a mesenteric lipoma; therefore, single-port laparoscopic surgery was performed. Laparoscopy revealed a small intestine volvulus secondary to the strangulation of a mesenteric lipoma. The band and tumor were removed. He had no postoperative complications and was discharged on postoperative day 6. Although this case was an emergency, it showed that single-port laparoscopic surgery can be a safe, useful, and efficacious procedure.

Absolute Intra-Molecular Distance Measurements with Ångström-Resolution using Anomalous Small-Angle X-ray Scattering

DOE PAGES

Zettl, Thomas; Mathew, Rebecca S.; Seifert, Sönke; ...

2016-05-31

Accurate determination of molecular distances is fundamental to understanding the structure, dynamics, and conformational ensembles of biological macromolecules. Here we present a method to determine the full,distance,distribution between small (~7 Å) gold labels attached to macromolecules with very high-precision(≤1 Å) and on an absolute distance scale. Our method uses anomalous small-angle X-ray scattering close to a gold absorption edge to separate the gold-gold interference pattern from other scattering contributions. Results for 10-30 bp DNA constructs achieve excellent signal-to-noise and are in good agreement with previous results obtained by single-energy,SAXS measurements without requiring the preparation and measurement of single labeled andmore » unlabeled samples. Finally, the use of small gold labels in combination with ASAXS read out provides an attractive approach to determining molecular distance distributions that will be applicable to a broad range of macromolecular systems.« less

Transition...One Small Step for a Young Girl, a Giant Leap for an Educational Community

ERIC Educational Resources Information Center

Terry, Shanta

2017-01-01

Can single-gender education foster student success? Can it work in a public setting? These questions have been asked many times over the past few decades. The answers have been inconclusive, with some studies saying that single-gender education truly works and others saying that it does not. The basis of the success or failure of single-gender…

Polymer Waveguides for Quantum Information

DTIC Science & Technology

2005-01-01

a single photon or a very small amount of light plays a critical role in establishing the quantum nature of the process. These materials offer...realizations of Mach-Zehnder interferometers for use in single- photon quantum communication systems. The Scope of the research for this grant: This...to the waveguide we make. We also intend to investigate the transmission of highly attenuated signals mimicking the single photon , which in turn

Single Cell Proteolytic Assays to Investigate Cancer Clonal Heterogeneity and Cell Dynamics Using an Efficient Cell Loading Scheme

NASA Astrophysics Data System (ADS)

Chen, Yu-Chih; Cheng, Yu-Heng; Ingram, Patrick; Yoon, Euisik

2016-06-01

Proteolytic degradation of the extracellular matrix (ECM) is critical in cancer invasion, and recent work suggests that heterogeneous cancer populations cooperate in this process. Despite the importance of cell heterogeneity, conventional proteolytic assays measure average activity, requiring thousands of cells and providing limited information about heterogeneity and dynamics. Here, we developed a microfluidic platform that provides high-efficiency cell loading and simple valveless isolation, so the proteolytic activity of a small sample (10-100 cells) can be easily characterized. Combined with a single cell derived (clonal) sphere formation platform, we have successfully demonstrated the importance of microenvironmental cues for proteolytic activity and also investigated the difference between clones. Furthermore, the platform allows monitoring single cells at multiple time points, unveiling different cancer cell line dynamics in proteolytic activity. The presented tool facilitates single cell proteolytic analysis using small samples, and our findings illuminate the heterogeneous and dynamic nature of proteolytic activity.

Detecting Noisy Events Using Waveform Cross-Correlation at Superarrays of Seismic Stations

NASA Astrophysics Data System (ADS)

von Seggern, D. H.; Tibuleac, I. M.

2007-12-01

Cross-correlation using master events, followed by stacking of the correlation series, has been shown to dramatically improve detection thresholds of small-to-medium seismic arrays. With the goal of lowering the detection threshold, determining relative magnitudes or moments, and characterizing sources by empirical Green's functions, we extend the cross-correlation methodology to include "superarrays" of seismic stations. The superarray concept naturally brings further benefits over conventional arrays and single-stations due to the fact that many distances and azimuths can be sampled. This extension is straightforward given the ease with which regional or global data from various stations or arrays can be currently accessed and combined into a single database. We demonstrate the capability of superarrays to detect and analyze events which lie below the detection threshold. This is aided by applying an F-statistic detector to the superarray cross-correlation stack and its components. Our first example illustrates the use of a superarray consisting of the Southern Great Basin Digital Seismic Network, a small-aperture array (NVAR) in Mina, Nevada and the Earthscope Transportable Array to detect events in California-Nevada areas. In our second example, we use a combination of small-to-medium arrays and single stations to study the rupture of the great Sumatra earthquake of 26 December 2004 and to detect its early aftershocks. The location and times of "detected" events are confirmed using a frequency- wavenumber method at the small-to-medium arrays. We propose that ad hoc superarrays can be used in many studies where conventional approaches previously used only single arrays or groups of single stations. The availability of near-real-time data from many networks and of archived data from, for instance, IRIS makes possible the easy assembly of superarrays. Furthermore, the continued improvement of seismic data availability and the continued growth in the number of world-wide seismic sensors will increasingly make superarrays an attractive choice for many studies.

Robust high-performance nanoliter-volume single-cell multiple displacement amplification on planar substrates.

PubMed

Leung, Kaston; Klaus, Anders; Lin, Bill K; Laks, Emma; Biele, Justina; Lai, Daniel; Bashashati, Ali; Huang, Yi-Fei; Aniba, Radhouane; Moksa, Michelle; Steif, Adi; Mes-Masson, Anne-Marie; Hirst, Martin; Shah, Sohrab P; Aparicio, Samuel; Hansen, Carl L

2016-07-26

The genomes of large numbers of single cells must be sequenced to further understanding of the biological significance of genomic heterogeneity in complex systems. Whole genome amplification (WGA) of single cells is generally the first step in such studies, but is prone to nonuniformity that can compromise genomic measurement accuracy. Despite recent advances, robust performance in high-throughput single-cell WGA remains elusive. Here, we introduce droplet multiple displacement amplification (MDA), a method that uses commercially available liquid dispensing to perform high-throughput single-cell MDA in nanoliter volumes. The performance of droplet MDA is characterized using a large dataset of 129 normal diploid cells, and is shown to exceed previously reported single-cell WGA methods in amplification uniformity, genome coverage, and/or robustness. We achieve up to 80% coverage of a single-cell genome at 5× sequencing depth, and demonstrate excellent single-nucleotide variant (SNV) detection using targeted sequencing of droplet MDA product to achieve a median allelic dropout of 15%, and using whole genome sequencing to achieve false and true positive rates of 9.66 × 10(-6) and 68.8%, respectively, in a G1-phase cell. We further show that droplet MDA allows for the detection of copy number variants (CNVs) as small as 30 kb in single cells of an ovarian cancer cell line and as small as 9 Mb in two high-grade serous ovarian cancer samples using only 0.02× depth. Droplet MDA provides an accessible and scalable method for performing robust and accurate CNV and SNV measurements on large numbers of single cells.

Crash testing of Louisiana's 3 1/2" diameter multi-directional, single steel post, small sign support : final report.

DOT National Transportation Integrated Search

1993-03-01

The Louisiana Department of Transportation and Development (LDOTD) contracted with the Texas Transportation Institute (TTI) to evaluate the impact characteristics of Louisiana's multi-directional, 8.9 cm (3-1/2 in) diameter steel post, small sigh sup...

Small Radioisotope Power System Testing at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Dugala, Gina; Bell, Mark; Oriti, Salvatore; Fraeman, Martin; Frankford, David; Duven, Dennis

2013-01-01

In April 2009, NASA Glenn Research Center (GRC) formed an integrated product team (IPT) to develop a Small Radioisotope Power System (SRPS) utilizing a single Advanced Stirling Convertor (ASC) with passive balancer. A single ASC produces approximately 80 We making this system advantageous for small distributed lunar science stations. The IPT consists of Sunpower, Inc., to provide the single ASC with a passive balancer, The Johns Hopkins University Applied Physics Laboratory (JHUAPL) to design an engineering model Single Convertor Controller (SCC) for an ASC with a passive balancer, and NASA GRC to provide technical support to these tasks and to develop a simulated lunar lander test stand. The single ASC with a passive balancer, simulated lunar lander test stand, and SCC were delivered to GRC and were tested as a system. The testing sequence at GRC included SCC fault tolerance, integration, electromagnetic interference (EMI), vibration, and extended operation testing. The SCC fault tolerance test characterized the SCCs ability to handle various fault conditions, including high or low bus power consumption, total open load or short circuit, and replacing a failed SCC card while the backup maintains control of the ASC. The integrated test characterized the behavior of the system across a range of operating conditions, including variations in cold-end temperature and piston amplitude, including the emitted vibration to both the sensors on the lunar lander and the lunar surface. The EMI test characterized the AC and DC magnetic and electric fields emitted by the SCC and single ASC. The vibration test confirms the SCCs ability to control the single ASC during launch. The extended operation test allows data to be collected over a period of thousands of hours to obtain long term performance data of the ASC with a passive balancer and the SCC. This paper will discuss the results of each of these tests.

Conversion of Methane into Methanol and Ethanol over Nickel Oxide on Ceria-Zirconia Catalysts in a Single Reactor

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

Okolie, Chukwuemeka; Belhseine, Yasmeen F.; Lyu, Yimeng

Direct conversion of methane into alcohols is a promising technology for converting stranded methane reserves into liquids that can be transported in pipelines and upgraded to value-added chemicals. We demonstrate that a catalyst consisting of small nickel oxide clusters supported on ceria-zirconia (NiO/CZ) can selectively oxidize methane to methanol and ethanol in a single, steady-state process at 723 K using O2 as an abundantly available oxidant. The presence of steam is required to obtain alcohols rather than CO2 as the product of catalytic combustion. The unusual activity of this catalyst is attributed to the synergy between the small Lewis acidicmore » NiO clusters and the redox-active CZ support, which also stabilizes the small NiO clusters.« less

Conversion of Methane to Methanol and Ethanol over Nickel Oxide on Ceria-Zirconia Catalysts in a Single Reactor

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

Okolie, Chukwuemeka; Belhseine, Yasmeen F.; Lyu, Yimeng

Here, the conversion of methane into alcohols under moderate reaction conditions is a promising technology for converting stranded methane reserves into liquids that can be transported in pipelines and upgraded to value-added chemicals. We demonstrate that a catalyst consisting of small nickel oxide clusters supported on ceria-zirconia (NiO/CZ) can convert methane to methanol and ethanol in a single, steady-state process at 723 K using O 2 as an abundantly available oxidant. The presence of steam is required to obtain alcohols rather than CO 2 as the product of catalytic combustion. The unusual activity of this catalyst is attributed to themore » synergy between the small Lewis acidic NiO clusters and the redox-active CZ support, which also stabilizes the small NiO clusters.« less

Conversion of Methane to Methanol and Ethanol over Nickel Oxide on Ceria-Zirconia Catalysts in a Single Reactor

DOE PAGES

Okolie, Chukwuemeka; Belhseine, Yasmeen F.; Lyu, Yimeng; ...

2017-08-08

Here, the conversion of methane into alcohols under moderate reaction conditions is a promising technology for converting stranded methane reserves into liquids that can be transported in pipelines and upgraded to value-added chemicals. We demonstrate that a catalyst consisting of small nickel oxide clusters supported on ceria-zirconia (NiO/CZ) can convert methane to methanol and ethanol in a single, steady-state process at 723 K using O 2 as an abundantly available oxidant. The presence of steam is required to obtain alcohols rather than CO 2 as the product of catalytic combustion. The unusual activity of this catalyst is attributed to themore » synergy between the small Lewis acidic NiO clusters and the redox-active CZ support, which also stabilizes the small NiO clusters.« less

Comprehensive profiling and quantitation of oncogenic mutations in non-small cell lung carcinoma using single-molecule amplification and re-sequencing technology.

PubMed

Shi, Jian; Yuan, Meng; Wang, Zhan-Dong; Xu, Xiao-Li; Hong, Lei; Sun, Shenglin

2017-02-01

The carcinogenesis of non-small cell lung carcinoma has been found to associate with activating and resistant mutations in the tyrosine kinase domain of specific oncogenes. Here, we assessed the type, frequency, and abundance of epithelial growth factor receptor, KRAS, BRAF, and ALK mutations in 154 non-small cell lung carcinoma specimens using single-molecule amplification and re-sequencing technology. We found that epithelial growth factor receptor mutations were the most prevalent (44.2%), followed by KRAS (18.8%), ALK (7.8%), and BRAF (5.8%) mutations. The type and abundance of the mutations in tumor specimens appeared to be heterogeneous. Thus, we conclude that identification of clinically significant oncogenic mutations may improve the classification of patients and provide valuable information for determination of the therapeutic strategies.

Hybrid single mode lasers fabricated using Si/SiO2/SiON micromachined platforms

NASA Technical Reports Server (NTRS)

Ksendzov, A.; Mansour, K.

2003-01-01

We have devised a hybridization scheme that, given suitable Fabri-Perot (F-P) ain medium, allows us to fabricate small, mechanically robust single frequency lasers in a wide spectral range, limited only by the transparency of the SiON material.

Investigation of a Multi-Anode Microchannel Plate PMT for Time-of-Flight PET

NASA Astrophysics Data System (ADS)

Choong, Woon-Seng

2010-10-01

We report on an investigation of a mulit-anode microchannel plate PMT for time-of-flight PET detector modules. The primary advantages of an MCP lie in its excellent timing properties (fast rise time and low transit time spread), compact size, and reasonably large active area, thus making it a good candidate for TOF applications. In addition, the anode can be segmented into an array of collection electrodes with fine pitch to attain good position sensitivity. In this paper, we investigate using the Photonis Planacon MCP-PMT with a pore size of 10 μm to construct a PET detector module, specifically for time-of-flight applications. We measure the single electron response by exciting the Planacon with pulsed laser diode. We also measure the performance of the Planacon as a PET detector by coupling a 4 mm×4 mm×10 mm LSO crystal to individual pixel to study its gain uniformity, energy resolution, and timing resolution. The rise time of the Planacon is 440 ps with pulse duration of about 1 ns. A transit time spread of 120 ps FWHM is achieved. The gain is fairly uniform across the central region of the Planacon, but drops off by as much as a factor of 2.5 around the edges. The energy resolution is fairly uniform across the Planacon with an average value of 18.6 ± 0.7% FWHM. While the average timing resolution of 252 ± 7 ps FWHM is achieved in the central region of the Planacon, it degrades to 280 ± 9 ps FWHM for edge pixels and 316 ± 15 ps FWHM for corner pixels. We compare the results with measurements performed with a fast timing conventional PMT (Hamamatsu R-9800). We find that the R9800, which has significantly higher PDE, has a better timing resolution than the Planacon. Furthermore, we perform detector simulations to calculate the improvement that can be achieved with a higher PDE Planacon. The calculation shows that the Planacon can achieve significantly better timing resolution if it can attain the same PDE as the R-9800, while only a 30% improvement is needed to yield a similar timing resolution as the R-9800.

A comparative DFT study of interactions of Au and small gold clusters Aun (n = 2-4) with CH3S and CH2 radicals

NASA Astrophysics Data System (ADS)

Blaško, Martin; Rajský, Tomáš; Urban, Miroslav

2017-03-01

We compare DFT binding energies (BEs) of Au and small gold clusters interacting with CH3S and CH2 ligands (Aun-L complexes, n = 1-4). The spin state and the binding mechanism in Aun-L varies with the participation of singly occupied non-bonding orbitals or doubly occupied lone-pair orbitals of a ligand and on the number of atoms (even or odd) of Aun. The highest BE, 354 kJ/mol, exhibits the Au3-CH2 complex with the covalent bond in which participate two singly occupied orbitals of the triplet state of CH2. With CH3S the highest BE (277 kJ/mol) is calculated for Au3-SCH3 with the single Au-S bond.

Synthesis of a large communications aperture using small antennas

NASA Technical Reports Server (NTRS)

Resch, George M.; Cwik, T. W.; Jamnejad, V.; Logan, R. T.; Miller, R. B.; Rogstad, Dave H.

1994-01-01

In this report we compare the cost of an array of small antennas to that of a single large antenna assuming both the array and single large antenna have equal performance and availability. The single large antenna is taken to be one of the 70-m antennas of the Deep Space Network. The cost of the array is estimated as a function of the array element diameter for three different values of system noise temperature corresponding to three different packaging schemes for the first amplifier. Array elements are taken to be fully steerable paraboloids and their cost estimates were obtained from commercial vendors. Array loss mechanisms and calibration problems are discussed. For array elements in the range 3 - 35 m there is no minimum in the cost versus diameter curve for the three system temperatures that were studied.

A novel percussion type droplet-on-demand generator

NASA Astrophysics Data System (ADS)

Hussain, Taaha; Patel, Priyesh; Balachandran, Ramanarayanan; Ladommatos, Nicos

2015-01-01

Numerous engineering applications require generation of droplets on demand which are of high uniformity and constant size. The common method to produce droplets is to drive liquid at high pressure through a small orifice/nozzle. The liquid stream disintegrates into small droplets. However this method normally requires large volumes of liquid and is not suitable for applications where single droplets of constant size is required. Such applications require droplet-on-demand generators which commonly employ piezoelectric or pneumatic actuation. It is well known that piezoelectric generators are hard to employ at high pressure and, high temperature applications, and the pneumatic generators often produce satellite (secondary) droplets. This paper describes the development of a novel percussion type droplet-on-demand generator, which overcomes some of the above difficulties and is capable of producing single droplets on demand. The generator consists of a cylindrical liquid filled chamber with a small orifice at the bottom. The top of the chamber is covered with a thin flexible metal disc. A small metal pin is employed to hammer/impact the top metal surface to generate a pressure pulse inside the liquid chamber. The movement and the momentum of the metal pin are controlled using a solenoid device. The pressure pulse generated overcomes the surface tension of the liquid meniscus at the exit of the orifice and ejects a single droplet. The work presented in this paper will demonstrate the capabilities of the droplet generator.

Effectiveness of backpack electrofishing for removal of non-native fishes from a small warm-water stream

USGS Publications Warehouse

Ward, David L.; O'neill, Matthew W.; Ka'apu-Lyons, Cassie

2015-01-01

Electrofishing is commonly used when renovating small streams to remove nuisance fishes but the likelihood of complete eradication of unwanted species, particularly warm-water fishes, is unknown. In October of 2008, we electrofished Bonita Creek, a small stream with base flows (<0.56 m3/s) in southern Arizona, and then treated the stream with rotenone to kill all of the remaining fish and quantify the effectiveness of single and multiple-pass electro fishing. Six, 100-m transects were electro fished on three consecutive days followed by a single treatment with rotenone. Fish caught using electrofishing were identified, counted and removed from each transect daily and then compared to numbers of dead fish collected during the subsequent rotenone application. Electrofishing effectiveness was highly variable among transects. Single-pass electrofishing caught an average of 23% (95% CI=5 to 40%) of the fish present, and three-pass electrofishing on consecutive days caught on average 55% (95% CI=28 to 83%) of the fish in each transect. Native Arizona fishes were more susceptible to electrofishing (77 % captured) than non-native species (54% captured), though native fish were rare. Transects in Bonita Creek averaged 3.6±1.5 m wide and 0.25±0.20 m deep (max depth 1.2 m). Bonita Creek is a small first-order stream which exhibits ideal conditions for backpack electrofishing, yet we captured a relatively small percentage of the fish present. This suggests that complete removal of non-native warm-water fishes using backpack electrofishing is not likely to be successful, especially in larger more complex streams.

Geosynchronous earth orbit/low earth orbit space object inspection and debris disposal: A preliminary analysis using a carrier satellite with deployable small satellites

NASA Astrophysics Data System (ADS)

Crockett, Derick

Detailed observations of geosynchronous satellites from earth are very limited. To better inspect these high altitude satellites, the use of small, refuelable satellites is proposed. The small satellites are stationed on a carrier platform in an orbit near the population of geosynchronous satellites. A carrier platform equipped with deployable, refuelable SmallSats is a viable option to inspect geosynchronous satellites. The propellant requirement to transfer to a targeted geosynchronous satellite, perform a proximity inspection mission, and transfer back to the carrier platform in a nearby orbit is determined. Convex optimization and traditional optimization techniques are explored, determining minimum propellant trajectories. Propellant is measured by the total required change in velocity, delta-v. The trajectories were modeled in a relative reference frame using the Clohessy-Wiltshire equations. Mass estimations for the carrier platform and the SmallSat were determined by using the rocket equation. The mass estimates were compared to the mass of a single, non-refuelable satellite performing the same geosynchronous satellite inspection missions. From the minimum delta-v trajectories and the mass analysis, it is determined that using refuelable SmallSats and a carrier platform in a nearby orbit can be more efficient than using a single non-refuelable satellite to perform multiple geosynchronous satellite inspections.

Effects of perforation number of blade on aerodynamic performance of dual-rotor small axial flow fans

NASA Astrophysics Data System (ADS)

Hu, Yongjun; Wang, Yanping; Li, Guoqi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

2015-04-01

Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-ɛ turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that: (1) Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. (2) The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. (3) Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

Derivation of two functional X chromosome centromeres from a single break bisecting the centromere of origin: Implications for centromere structure

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

Schonberg, S.A.; Quarles, C.; Tifft, C.

1994-09-01

The precise nature of the functional human centromeric sequences remains a matter of some controversy. Evidence has accumulated over the past several years that directly implicates alphoid repeats as a critical component. We report a child with dysmorphic features consistent with the recently described small ring X syndrome, with a constitutional karyotype that addresses this issue. At 5 1/2 months, the patient was a small, hypotonic, delayed female with brachycephaly, a broad forehead, prominent nasal root, synophorous, small mouth, and cup-shaped ears with prominent lobules, as well as microcornea, and pendular nystagmus. Hand abnormalities included single palmar creases and shortmore » tapered fingers. In addition to mosaicism for a small ring chromosome derived from the proximal short arm of the X, the proband has, in all cells, a monocentric isochromosome for the long arm of the X. The karyotype is interpreted as 46,X,iso(Xq)/47,X,iso(Xq),r(Xp11cen). We present routine karyotypic and FISH analysis of the rearranged X chromosomes. We propose that the only mechanism consistent with this karyotype is that of a two-break rearrangement with one break bisecting a centromere in such a way as to retain functional centromeric activity in each of the separated regions. The second break, proximal in the short arm, allows for ring chromosome formation with the bisected centromere. The iso(Xq) arises by the classical mechanism of post-replication sister-reunion. The formation of two functional centromeres by a single break through the {open_quotes}parental{close_quotes} centromere indicates that the functional activity must be in a repeated component of the centromeric DNA and argues strongly against the requirement for any single gene in cis orientation.« less

The association between cecal insertion time and colorectal neoplasm detection

PubMed Central

2013-01-01

Background Information on the impact of cecal insertion time on colorectal neoplasm detection is limited. Our objective was to determine the association between cecal insertion time and colorectal neoplasm detection rate in colonoscopy screening. Methods We performed a cross-sectional study of 12,679 consecutive subjects aged 40–79 years undergoing screening colonoscopy in routine health check-ups at the Center for Health Promotion of the Samsung Medical Center from December 2007 to June 2009. Fixed effects logistic regression conditioning on colonoscopist was used to eliminate confounding due to differences in technical ability and other characteristics across colonoscopists. Results The mean cecal insertion time was 5.9 (SD, 4.4 minutes). We identified 4,249 (33.5%) participants with colorectal neoplasms, of whom 1,956 had small single adenomas (<5 mm), 595 had medium single adenomas (5–9 mm), and 1,699 had multiple adenomas or advanced colorectal neoplasms. The overall rates of colorectal neoplasm detection by quartiles of cecal insertion time were 36.8%, 33.4%, 32.7%, and 31.0%, respectively (p trend <0.001).The odds for small single colorectal adenoma detection was 16% lower (adjusted OR 0.84; 95% CI 0.71 to 0.99) in the fourth compared to the first quartile of insertion time (p trend 0.005). Insertion time was not associated with the detection rate of single adenomas ≥5 mm, multiple adenomas or advanced colorectal neoplasms. Conclusion Shorter insertion times were associated with increased rates of detection of small colorectal adenomas <5 mm. Cecal insertion time may be clinically relevant as missed small colorectal adenomas may progress to more advanced lesions. PMID:23915303

Comparative Chloroplast Genomes of Photosynthetic Orchids: Insights into Evolution of the Orchidaceae and Development of Molecular Markers for Phylogenetic Applications

PubMed Central

Niu, Zhi-Tao; Liu, Wei; Xue, Qing-Yun; Ding, Xiao-Yu

2014-01-01

The orchid family Orchidaceae is one of the largest angiosperm families, including many species of important economic value. While chloroplast genomes are very informative for systematics and species identification, there is very limited information available on chloroplast genomes in the Orchidaceae. Here, we report the complete chloroplast genomes of the medicinal plant Dendrobium officinale and the ornamental orchid Cypripedium macranthos, demonstrating their gene content and order and potential RNA editing sites. The chloroplast genomes of the above two species and five known photosynthetic orchids showed similarities in structure as well as gene order and content, but differences in the organization of the inverted repeat/small single-copy junction and ndh genes. The organization of the inverted repeat/small single-copy junctions in the chloroplast genomes of these orchids was classified into four types; we propose that inverted repeats flanking the small single-copy region underwent expansion or contraction among Orchidaceae. The AT-rich regions of the ycf1 gene in orchids could be linked to the recombination of inverted repeat/small single-copy junctions. Relative species in orchids displayed similar patterns of variation in ndh gene contents. Furthermore, fifteen highly divergent protein-coding genes were identified, which are useful for phylogenetic analyses in orchids. To test the efficiency of these genes serving as markers in phylogenetic analyses, coding regions of four genes (accD, ccsA, matK, and ycf1) were used as a case study to construct phylogenetic trees in the subfamily Epidendroideae. High support was obtained for placement of previously unlocated subtribes Collabiinae and Dendrobiinae in the subfamily Epidendroideae. Our findings expand understanding of the diversity of orchid chloroplast genomes and provide a reference for study of the molecular systematics of this family. PMID:24911363

Comparative chloroplast genomes of photosynthetic orchids: insights into evolution of the Orchidaceae and development of molecular markers for phylogenetic applications.

PubMed

Luo, Jing; Hou, Bei-Wei; Niu, Zhi-Tao; Liu, Wei; Xue, Qing-Yun; Ding, Xiao-Yu

2014-01-01

The orchid family Orchidaceae is one of the largest angiosperm families, including many species of important economic value. While chloroplast genomes are very informative for systematics and species identification, there is very limited information available on chloroplast genomes in the Orchidaceae. Here, we report the complete chloroplast genomes of the medicinal plant Dendrobium officinale and the ornamental orchid Cypripedium macranthos, demonstrating their gene content and order and potential RNA editing sites. The chloroplast genomes of the above two species and five known photosynthetic orchids showed similarities in structure as well as gene order and content, but differences in the organization of the inverted repeat/small single-copy junction and ndh genes. The organization of the inverted repeat/small single-copy junctions in the chloroplast genomes of these orchids was classified into four types; we propose that inverted repeats flanking the small single-copy region underwent expansion or contraction among Orchidaceae. The AT-rich regions of the ycf1 gene in orchids could be linked to the recombination of inverted repeat/small single-copy junctions. Relative species in orchids displayed similar patterns of variation in ndh gene contents. Furthermore, fifteen highly divergent protein-coding genes were identified, which are useful for phylogenetic analyses in orchids. To test the efficiency of these genes serving as markers in phylogenetic analyses, coding regions of four genes (accD, ccsA, matK, and ycf1) were used as a case study to construct phylogenetic trees in the subfamily Epidendroideae. High support was obtained for placement of previously unlocated subtribes Collabiinae and Dendrobiinae in the subfamily Epidendroideae. Our findings expand understanding of the diversity of orchid chloroplast genomes and provide a reference for study of the molecular systematics of this family.

Gunn and Heid: Teaching Small Group Development with Reality TV

ERIC Educational Resources Information Center

Kopaczewski, Shana

2017-01-01

Courses: Small group communication or any courses with units on group/team work. Objective: In this single-class activity, students will use reality TV to identify Tuckman's five phases of group development: forming, storming, norming, performing, and adjourning. Students analyze how phases of group development manifest through group interaction…

VIEW OF REAR YARD WITH PLUMERIA TREES AND SMALL PALMS. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF REAR YARD WITH PLUMERIA TREES AND SMALL PALMS. VIEW FACING EAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Three-Bedroom Single-Family Types 8 and 11, Birch Circle, Elm Drive, Elm Circle, and Date Drive, Pearl City, Honolulu County, HI

Comparisons of estimates of annual exceedance-probability discharges for small drainage basins in Iowa, based on data through water year 2013 : [summary].

DOT National Transportation Integrated Search

2015-01-01

Traditionally, the Iowa DOT has used the Iowa Runoff Chart and single-variable regional regression equations (RREs) from a USGS report : (published in 1987) as the primary methods to estimate annual exceedance-probability discharge : (AEPD) for small...

In Situ Oxidation Synthesis of p-Type Composite with Narrow-Bandgap Small Organic Molecule Coating on Single-Walled Carbon Nanotube: Flexible Film and Thermoelectric Performance.

PubMed

Gao, Caiyan; Chen, Guangming

2018-03-01

Although composites of organic polymers or n-type small molecule/carbon nanotube (CNT) have achieved significant advances in thermoelectric (TE) applications, p-type TE composites of small organic molecules as thick surface coating layers on the surfaces of inorganic nanoparticles still remain a great challenge. Taking advantage of in situ oxidation reaction of thieno[3,4-b]pyrazine (TP) into TP di-N-oxide (TPNO) on single-walled CNT (SWCNT) surface, a novel synthesis strategy is proposed to achieve flexible films of TE composites with narrow-bandgap (1.19 eV) small molecule coating on SWCNT surface. The TE performance can be effectively enhanced and conveniently tuned by poly(sodium-p-styrenesulfonate) content, TPNO/SWCNT mass ratio, and posttreatment by various polar solvents. The maximum of the composite power factor at room temperature is 29.4 ± 1.0 µW m -1 K -2 . The work presents a way to achieve flexible films of p-type small organic molecule/inorganic composites with clear surface coating morphology for TE application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DISTRIBUTION AND FREQUENCY OF CORAL DISEASES IN THE FLORIDA KEYS AND THE DRY TORTUGAS

EPA Science Inventory

Reports of coral diseases affecting reefs in the Western Atlantic have been increasing. Few studies have attempted to document the incidences of different coral diseases in a single geographic area. Most studies have focused on a single disease within a small geographic area. Thi...

Capillary Electrophoretic Technologies for Single Cell Metabolomics

ERIC Educational Resources Information Center

Lapainis, Theodore E.

2009-01-01

Understanding the functioning of the brain is hindered by a lack of knowledge of the full complement of neurotransmitters and neuromodulatory compounds. Single cell measurements aid in the discovery of neurotransmitters used by small subsets of neurons that would be diluted below detection limits or masked by ubiquitous compounds when working with…

Presentation Software and the Single Computer.

ERIC Educational Resources Information Center

Brown, Cindy A.

1998-01-01

Shows how the "Kid Pix" software and a single multimedia computer can aid classroom instruction for kindergarten through second grade. Topics include using the computer as a learning center for small groups of students; making a "Kid Pix" slide show; using it as an electronic chalkboard; and creating curriculum-related…

Self-consistent quasi-static parallel electric field associated with substorm growth phase

NASA Astrophysics Data System (ADS)

Le Contel, O.; Pellat, R.; Roux, A.

2000-06-01

A new approach is proposed to calculate the self-consistent parallel electric field associated with the response of a plasma to quasi-static electromagnetic perturbations (ωωd<ω and ωd>ω (ωd being the bounce averaged magnetic drift frequency equal to kyvd, where ky is the wave number in the y direction and vd the bounce averaged magnetic drift velocity). The first regime (ωd<ω) corresponds to small particle energy and/or small ky, while the second regime (ωd>ω) is adapted to large energies and/or large ky. In particular, in the limit ωd<ω and |vd|<|uy|, where uy is the diamagnetic velocity proportional to the pressure gradient, we find a parallel electric field proportional to the pressure gradient and directed toward the ionosphere in the dusk sector and toward the equator in the dawn sector. This parallel electric field corresponds to a potential drop of a few hundred volts that can accelerate electrons and produce a differential drift between electrons and ions.

A wireless neural recording system with a precision motorized microdrive for freely behaving animals

PubMed Central

Hasegawa, Taku; Fujimoto, Hisataka; Tashiro, Koichiro; Nonomura, Mayu; Tsuchiya, Akira; Watanabe, Dai

2015-01-01

The brain is composed of many different types of neurons. Therefore, analysis of brain activity with single-cell resolution could provide fundamental insights into brain mechanisms. However, the electrical signal of an individual neuron is very small, and precise isolation of single neuronal activity from moving subjects is still challenging. To measure single-unit signals in actively behaving states, establishment of technologies that enable fine control of electrode positioning and strict spike sorting is essential. To further apply such a single-cell recording approach to small brain areas in naturally behaving animals in large spaces or during social interaction, we developed a compact wireless recording system with a motorized microdrive. Wireless control of electrode placement facilitates the exploration of single neuronal activity without affecting animal behaviors. Because the system is equipped with a newly developed data-encoding program, the recorded data are readily compressed almost to theoretical limits and securely transmitted to a host computer. Brain activity can thereby be stably monitored in real time and further analyzed using online or offline spike sorting. Our wireless recording approach using a precision motorized microdrive will become a powerful tool for studying brain mechanisms underlying natural or social behaviors. PMID:25597933

Small, high-pressure, liquid oxygen turbopump

NASA Technical Reports Server (NTRS)

Csomor, A.

1978-01-01

A small, high-pressure, LOX turbopump was designed, fabricated, and tested. The pump was of a single-stage, centrifugal type; power to the pump was supplied by a single-stage, partial-admission, axial-impulse turbine. Design conditions included an operating speed of 7330 rad/sec (70,000 rpm) pump discharge pressure of 2977 N/sq cm (4318 psia), and a pump flowrate of 16.4 kg/s (36.21 lb/sec). The turbine was propelled by LOX/LH2 combustion products at 1041 K (1874 R) inlet temperature, and at a design pressure ratio of 1.424. Test data obtained with the turbopump are presented and mechanical performance is discussed.

Acoustic ranging of small arms fire using a single sensor node collocated with the target.

PubMed

Lo, Kam W; Ferguson, Brian G

2015-06-01

A ballistic model-based method, which builds upon previous work by Lo and Ferguson [J. Acoust. Soc. Am. 132, 2997-3017 (2012)], is described for ranging small arms fire using a single acoustic sensor node collocated with the target, without a priori knowledge of the muzzle speed and ballistic constant of the bullet except that they belong to a known two-dimensional parameter space. The method requires measurements of the differential time of arrival and differential angle of arrival of the muzzle blast and ballistic shock wave at the sensor node. Its performance is evaluated using both simulated and real data.

Fusion splicing small-core photonic crystal fibers and single-mode fibers by controlled air hole collapse

NASA Astrophysics Data System (ADS)

Zhou, Xuanfeng; Chen, Zilun; Chen, Haihuan; Hou, Jing

2012-11-01

A method based on controlled air hole collapse for low-loss fusion splicing small-core photonic crystal fibers (PCFs) and single-mode fibers (SMFs) was demonstrated. A taper rig was used to control air hole collapse accurately to enlarge the MFDs of PCFs which was then spliced with SMFs using a fusion splicer. An optimum mode field match at the interface of PCF-SMF was achieved and a low-loss with 0.64 dB was obtained from 3.57 dB for a PCF with 4 μm MFD and a SMF with 10.4 μm MFD experimentally.

Optimized design and performance of a shared pump single clad 2 μm TDFA

NASA Astrophysics Data System (ADS)

Tench, Robert E.; Romano, Clément; Delavaux, Jean-Marc

2018-05-01

We report the design, experimental performance, and simulation of a single stage, co- and counter-pumped Tm-doped fiber amplifier (TDFA) in the 2 μm signal wavelength band with an optimized 1567 nm shared pump source. We investigate the dependence of output power, gain, and efficiency on pump coupling ratio and signal wavelength. Small signal gains of >50 dB, an output power of 2 W, and small signal noise figures of <3.5 dB are demonstrated. Simulations of TDFA performance agree well with the experimental data. We also discuss performance tradeoffs with respect to amplifier topology for this simple and efficient TDFA.

Single field double inflation and primordial black holes

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

Kannike, K.; Marzola, L.; Raidal, M.

Within the framework of scalar-tensor theories, we study the conditions that allow single field inflation dynamics on small cosmological scales to significantly differ from that of the large scales probed by the observations of cosmic microwave background. The resulting single field double inflation scenario is characterised by two consequent inflation eras, usually separated by a period where the slow-roll approximation fails. At large field values the dynamics of the inflaton is dominated by the interplay between its non-minimal coupling to gravity and the radiative corrections to the inflaton self-coupling. For small field values the potential is, instead, dominated by amore » polynomial that results in a hilltop inflation. Without relying on the slow-roll approximation, which is invalidated by the appearance of the intermediate stage, we propose a concrete model that matches the current measurements of inflationary observables and employs the freedom granted by the framework on small cosmological scales to give rise to a sizeable population of primordial black holes generated by large curvature fluctuations. We find that these features generally require a potential with a local minimum. We show that the associated primordial black hole mass function is only approximately lognormal.« less

Feasibility study on the ultra-small launch vehicle

NASA Astrophysics Data System (ADS)

Hayashi, T.; Matsuo, H.; Yamamoto, H.; Orii, T.; Kimura, A.

1986-10-01

An idea for a very small satellite launcher and a very small satellite is presented. The launcher is a three staged solid rocket based on a Japanese single stage sounding rocket S-520. Its payload capability is estimated to be 17 kg into 200 x 1000 km elliptical orbit. The spin-stabilized satellite with sun-pointing capability, though small, has almost all functions necessary for usual satellites. In its design, universality is stressed to meet various kinds of mission interface requirements; it can afford 5 kg to mission instruments.

Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

NASA Technical Reports Server (NTRS)

Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

2014-01-01

The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We lso report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

Single exposure three-dimensional imaging of dusty plasma clusters.

PubMed

Hartmann, Peter; Donkó, István; Donkó, Zoltán

2013-02-01

We have worked out the details of a single camera, single exposure method to perform three-dimensional imaging of a finite particle cluster. The procedure is based on the plenoptic imaging principle and utilizes a commercial Lytro light field still camera. We demonstrate the capabilities of our technique on a single layer particle cluster in a dusty plasma, where the camera is aligned and inclined at a small angle to the particle layer. The reconstruction of the third coordinate (depth) is found to be accurate and even shadowing particles can be identified.

On the growth rate of gallstones in the human gallbladder

NASA Astrophysics Data System (ADS)

Nudelman, I.

1993-05-01

The growth rate of a single symmetrically oval shaped gallbladder stone weighing 10.8 g was recorded over a period of six years before surgery and removal. The length of the stone was measured by ultrasonography and the growth rate was found to be linear with time, with a value of 0.4 mm/year. A smaller stone growing in the wall of the gallbladder was detected only three years before removal and grew at a rate of ˜ 1.33 mm/year. The morphology and metallic ion chemical composition of the large stone and of a randomly selected small stone weighing about 1.1 g, extracted from another patient, were analyzed and compared. It was found that the large stone contained besides calcium also lead, whereas the small stone contained mainly calcium. It is possible that the lead causes a difference in mechanism between the growth of a single large and growth of multiple small gallstones.

Low-Dead-Volume Inlet for Vacuum Chamber

NASA Technical Reports Server (NTRS)

Naylor, Guy; Arkin, C.

2010-01-01

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead -volume. As a result, a high -vacuum gas inlet was developed with low dead -volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

Low-Dead-Volume Inlet for Vacuum Chamber

NASA Technical Reports Server (NTRS)

Naylor, Guy; Arkin, C.

2011-01-01

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead-volume. As a result, a high-vacuum gas inlet was developed with low dead-volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

Transit of pharmaceutical dosage forms through the small intestine.

PubMed Central

Davis, S S; Hardy, J G; Fara, J W

1986-01-01

The gastrointestinal transit of pharmaceutical dosage forms has been measured in 201 studies in normal subjects using gamma scintigraphy. Solutions, small pellets, and single units (matrix tablets and osmotic pumps) were administered with different amounts of food in the stomach, ranging from fasted state to heavy breakfast. Gastric emptying was affected by the nature of the dosage form and the presence of food in the stomach. Solutions and pellets were emptied even when the stomach was in the digestive mode, while single units were retained for long periods of time, depending on the size of the meal. In contrast, measured intestinal transit times were independent of the dosage form and fed state. The small intestinal transit time of about three hours (mean +/- 1 h SEM) has implications for the design of dosage forms for the sustained release of drugs in specific positions in the gastrointestinal tract. PMID:3732895

Identification of the duodenal papilla by colon capsule endoscope.

PubMed

Karagiannis, S; Dücker, C; Dautel, P; Strubenhoff, J; Faiss, S

2010-07-01

The sensitivity of small-bowel capsule endoscopy in visualizing a single finding present in everyone, the duodenal papilla, is limited. In this retrospective case series study we evaluated whether the duodenal papilla can be better visualized by a capsule endoscope equipped with cameras on both ends. The recordings of 45 colonic capsule endoscopies (PillCam Colon) performed in a single tertiary center were re-evaluated seeking for the duodenal papilla. The two-hour sleeping period of the colon capsule endoscopy system led to the imaging of duodenum in 10 / 45 patients. The duodenal papilla was identified in 6 / 10 (60 %) patients while the number of frames where the papilla was clearly visualized ranged from 2 - 9. Consequently, a small-bowel capsule endoscope containing two cameras could better identify the duodenal papilla and theoretically other obscure areas of the small bowel, expanding its diagnostic accuracy.

Theoretical Investigation of Single-Molecule Sensing Using Nanotube-Enhanced Circular Dichroism.

PubMed

Silva, Jaime; Milne, Bruce F; Nogueira, Fernando

2018-06-19

First-principles calculations have been used to investigate the potential use of circular dichroism (CD) spectroscopy in single-molecule sensing. Using a real-space implementation of time-dependent density functional theory (TDDFT), several systems involving single-walled carbon nanotubes (SWCNT) and small molecules have been studied to evaluate their CD response. Large induced CD (ICD) effects, differing for each test molecule, were observed in all SWCNT-molecule complexes. As the SWCNT used in this study shows no intrinsic CD response, the ICD spectra are the result of interaction with the small molecules. This finding is general and independent of the (a)chiral nature of the adsorbed molecule. Our results indicate that it is possible to design a system that uses SWCNT for detection of molecules using the change in CD spectrum of the system induced by adsorption of the molecule onto the SWCNT surface.

High peak-power kilohertz laser system employing single-stage multi-pass amplification

DOEpatents

Shan, Bing; Wang, Chun; Chang, Zenghu

2006-05-23

The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

Single-molecule chemo-mechanical unfolding reveals multiple transition state barriers in a small single-domain protein

NASA Astrophysics Data System (ADS)

Guinn, Emily J.; Jagannathan, Bharat; Marqusee, Susan

2015-04-01

A fundamental question in protein folding is whether proteins fold through one or multiple trajectories. While most experiments indicate a single pathway, simulations suggest proteins can fold through many parallel pathways. Here, we use a combination of chemical denaturant, mechanical force and site-directed mutations to demonstrate the presence of multiple unfolding pathways in a simple, two-state folding protein. We show that these multiple pathways have structurally different transition states, and that seemingly small changes in protein sequence and environment can strongly modulate the flux between the pathways. These results suggest that in vivo, the crowded cellular environment could strongly influence the mechanisms of protein folding and unfolding. Our study resolves the apparent dichotomy between experimental and theoretical studies, and highlights the advantage of using a multipronged approach to reveal the complexities of a protein's free-energy landscape.

Small Area Income and Poverty Estimates (SAIPE): 2010 Highlights

ERIC Educational Resources Information Center

US Census Bureau, 2011

2011-01-01

This document presents 2010 data from the Small Area Income and Poverty Estimates (SAIPE) program of the U.S. Census Bureau. The SAIPE program produces poverty estimates for the total population and median household income estimates annually for all counties and states. SAIPE data also produces single-year poverty estimates for the school-age…

Recent Developments in VSD Imaging of Small Neuronal Networks

ERIC Educational Resources Information Center

Hill, Evan S.; Bruno, Angela M.; Frost, William N.

2014-01-01

Voltage-sensitive dye (VSD) imaging is a powerful technique that can provide, in single experiments, a large-scale view of network activity unobtainable with traditional sharp electrode recording methods. Here we review recent work using VSDs to study small networks and highlight several results from this approach. Topics covered include circuit…

Parameters of loop-controlled magnetic rheology drive for segmented large mirror

NASA Astrophysics Data System (ADS)

Deulin, Eugeni A.; Mikhailov, Valeri P.; Eliseev, Oleg N.; Sytchev, Victor V.

2000-07-01

The design, parameters and the amplitude-frequency analysis of the new magnetic rheology (MR) drive are presented. The combination of hydrostatic carrier, MR hydraulic loop control, elastic thin wall seal joined in a single unit ensures small positioning error nm and small time of response T

The Entrance and Exit Effects in Small Electrochemical Filter-Press Reactors Used in the Laboratory

ERIC Educational Resources Information Center

Frias-Ferrer, Angel; Gonzalez-Garcia, Jose; Saez, Veronica; Exposito, Eduardo; Sanchez-Sanchez, Carlos M.; Mantiel, Vicente; Walsh, Frank C.; Aldaz, Antonio; Walsh, Frank C.

2005-01-01

A laboratory experiment designed to examine the entrance and exit effects in small electrochemical filter-press reactors used in the laboratory is presented. The single compartment of the filter-press reactor is filled with different turbulence promoters to study their influence as compared to the empty configuration.

A Framework for Mobile Apps in Colleges and Universities: Data Mining Perspective

ERIC Educational Resources Information Center

Singh, Archana; Ranjan, Jayanthi

2016-01-01

The Enterprise mobility communication technology provides easy and quick accessibility to data and information integrated into one single touch point device. This device incorporates or integrates all the processes into small applications or App and thus increases the workforce capability of knowledge workers. "App" which is a small set…

Feasibility of observing small differences in friction mean effective pressure between different lubricating oil formations using small, single-cylinder motored engine rig

DOE PAGES

Rohr, William F.; Nguyen, Ke; Bunting, Bruce G.; ...

2015-09-01

Here, the feasibility of using a motored single-cylinder 517 cc diesel engine to observe small frictional differences between oil formulations is investigated. Friction mean effective pressure (FMEP) is measured and compared for an SAE 10W-30 and an SAE 5W-20 oil in three stages of production: base oil, commercial oil without a friction and wear reducing additive, and fully formulated commercial oil. In addition, a commercial SAE 5W-30 engine oil is investigated. Friction mean effective pressure is plotted versus oil dynamic viscosity to compare the lubricant FMEP at a given viscosity. Linear regressions and average friction mean effective pressure are usedmore » as a secondary means of comparing FMEP for the various oil formulations. Differences between the oils are observed with the base oil having higher friction at a given viscosity but a lower average FMEP due to the temperature distribution of the test and lower viscosities reached by the base oil. The commercial oil is shown to have both a higher FMEP at a given viscosity and a higher average FMEP than the commercial oil without a friction and wear reducing additive. The increase in friction for the oil without a friction and wear reduction additive indicates that the operational regime of the engine may be out of the bounds of the optimal regime for the additive or that the additive is more optimized for wear reduction. Results show that it is feasible to observe small differences in FMEP between lubricating oil formulations using a small, single-cylinder motored engine.« less

Trap density of states in small-molecule organic semiconductors: A quantitative comparison of thin-film transistors with single crystals

NASA Astrophysics Data System (ADS)

Kalb, Wolfgang L.; Haas, Simon; Krellner, Cornelius; Mathis, Thomas; Batlogg, Bertram

2010-04-01

We show that it is possible to reach one of the ultimate goals of organic electronics: producing organic field-effect transistors with trap densities as low as in the bulk of single crystals. We studied the spectral density of localized states in the band gap [trap density of states (trap DOS)] of small-molecule organic semiconductors as derived from electrical characteristics of organic field-effect transistors or from space-charge-limited current measurements. This was done by comparing data from a large number of samples including thin-film transistors (TFT’s), single crystal field-effect transistors (SC-FET’s) and bulk samples. The compilation of all data strongly suggests that structural defects associated with grain boundaries are the main cause of “fast” hole traps in TFT’s made with vacuum-evaporated pentacene. For high-performance transistors made with small-molecule semiconductors such as rubrene it is essential to reduce the dipolar disorder caused by water adsorbed on the gate dielectric surface. In samples with very low trap densities, we sometimes observe a steep increase in the trap DOS very close (<0.15eV) to the mobility edge with a characteristic slope of 10-20 meV. It is discussed to what degree band broadening due to the thermal fluctuation of the intermolecular transfer integral is reflected in this steep increase in the trap DOS. Moreover, we show that the trap DOS in TFT’s with small-molecule semiconductors is very similar to the trap DOS in hydrogenated amorphous silicon even though polycrystalline films of small-molecules with van der Waals-type interaction on the one hand are compared with covalently bound amorphous silicon on the other hand.

Feasibility of observing small differences in friction mean effective pressure between different lubricating oil formations using small, single-cylinder motored engine rig

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

Rohr, William F.; Nguyen, Ke; Bunting, Bruce G.

Here, the feasibility of using a motored single-cylinder 517 cc diesel engine to observe small frictional differences between oil formulations is investigated. Friction mean effective pressure (FMEP) is measured and compared for an SAE 10W-30 and an SAE 5W-20 oil in three stages of production: base oil, commercial oil without a friction and wear reducing additive, and fully formulated commercial oil. In addition, a commercial SAE 5W-30 engine oil is investigated. Friction mean effective pressure is plotted versus oil dynamic viscosity to compare the lubricant FMEP at a given viscosity. Linear regressions and average friction mean effective pressure are usedmore » as a secondary means of comparing FMEP for the various oil formulations. Differences between the oils are observed with the base oil having higher friction at a given viscosity but a lower average FMEP due to the temperature distribution of the test and lower viscosities reached by the base oil. The commercial oil is shown to have both a higher FMEP at a given viscosity and a higher average FMEP than the commercial oil without a friction and wear reducing additive. The increase in friction for the oil without a friction and wear reduction additive indicates that the operational regime of the engine may be out of the bounds of the optimal regime for the additive or that the additive is more optimized for wear reduction. Results show that it is feasible to observe small differences in FMEP between lubricating oil formulations using a small, single-cylinder motored engine.« less

Too attractive: the growing problem of magnet ingestions in children.

PubMed

Brown, Julie C; Otjen, Jeffrey P; Drugas, George T

2013-11-01

Small, powerful magnets are increasingly available in toys and other products and pose a health risk. Small spherical neodymium magnets marketed since 2008 are of particular concern. The objective of this study was to determine the incidence, characteristics, and management of single and multiple-magnet ingestions over time. Magnet ingestion cases at a tertiary children's hospital were identified using radiology reports from June 2002 to December 2012. Cases were verified by chart and imaging review. Relative risk regressions were used to determine changes in the incidence of ingestions and interventions over time. Of 56 cases of magnet ingestion, 98% occurred in 2006 or later, and 57% involved multiple magnets. Median age was 8 years (range, 0-18 years). Overall, 21% of single and 88% of multiple ingestions had 2 or more imaging series obtained, whereas no single and 56.3% of multiple ingestions required intervention (25.0% endoscopy, 18.8% surgery, 12.5% both). Magnet ingestions increased in 2010 to 2012 compared with 2007 to 2009 (relative risk, 1.9; 95% confidence interval, 1.2-3.0). Small, spherical magnets likely from magnet sets comprised 27% of ingestions, all ingested 2010 or later: 86% involved multiple magnets, 50% of which required intervention. Excluding these cases, ingestions of other magnets did not increase in 2010 to 2012 compared with 2007 to 2009 (relative risk, 0.94; 95% confidence interval, 0.6-1.4). The incidence of pediatric magnet ingestions and subsequent interventions has increased over time. Multiple-magnet ingestions result in high utilization of radiological imaging and surgical interventions. Recent increases parallel the increased availability of small, spherical magnet sets. Young and at-risk children should not have access to these and other small magnets. Improved regulation and magnet safety standards are needed.

Production of vertical arrays of small diameter single-walled carbon nanotubes

DOEpatents

Hauge, Robert H; Xu, Ya-Qiong

2013-08-13

A hot filament chemical vapor deposition method has been developed to grow at least one vertical single-walled carbon nanotube (SWNT). In general, various embodiments of the present invention disclose novel processes for growing and/or producing enhanced nanotube carpets with decreased diameters as compared to the prior art.

Single-Crystal Germanium Core Optoelectronic Fibers

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

Ji, Xiaoyu; Page, Ryan L.; Chaudhuri, Subhasis

Synthesis and fabrication of high-quality, small-core single-crystal germanium fibers that are photosensitive at the near-infrared and have low optical losses ≈1 dB cm-1 at 2 μm are reported. These fibers have potential applications in fiber-based spectroscopic imaging, nonlinear optical devices, and photodetection at the telecommunication wavelengths.

Prologue: Reading Comprehension Is Not a Single Ability

ERIC Educational Resources Information Center

Catts, Hugh W.; Kamhi, Alan G.

2017-01-01

Purpose: In this initial article of the clinical forum on reading comprehension, we argue that reading comprehension is not a single ability that can be assessed by one or more general reading measures or taught by a small set of strategies or approaches. Method: We present evidence for a multidimensional view of reading comprehension that…

Teaching Discrete and Programmable Logic Design Techniques Using a Single Laboratory Board

ERIC Educational Resources Information Center

Debiec, P.; Byczuk, M.

2011-01-01

Programmable logic devices (PLDs) are used at many universities in introductory digital logic laboratories, where kits containing a single high-capacity PLD replace "standard" sets containing breadboards, wires, and small- or medium-scale integration (SSI/MSI) chips. From the pedagogical point of view, two problems arise in these…

Microfabricated particle focusing device

DOEpatents

Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

2013-04-23

A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

75 FR 19665 - Notice of Action Subject to Intergovernmental Review Under Executive Order 12372

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-15

... the address section. A copy of this notice also is being furnished to the respective State single... area-wide small business assistance plan adopted by a State authorized agency. DATES: A State single..., women, exporters, the disabled, and minorities. SBDC Program Requirements An SBDC must meet programmatic...

Porrocaecum parvum n. sp. and P. reticulatum (Linstow, 1899) (Nematoda: Ascaridoidea) from birds in China.

PubMed

Li, Liang; Guo, Yan-Ning; Zhang, Lu-Ping

2015-10-01

Porrocaecum parvum n. sp. is described from the grey-faced buzzard Butastur indicus (Gmelin) (Accipitriformes: Accipitridae) in China. The new species differs from its congeners in having well-developed cervical alae, small interlabia and very short intestinal caecum (0.34 mm long, representing 11.9% of oesophageal length) and in the number and arrangement of the caudal papillae (29 pairs in total, arranged as follows: 21 pairs precloacal, single double pair paracloacal and seven pairs postcloacal) and in the morphology of the male tail. In addition, Porrocaecum reticulatum (Linstow, 1899), collected from the purple heron Ardea purpurea L., the grey heron A. cinerea L. and the little egret Egretta garzetta (L.) (Pelecaniformes: Ardeidae) in China, was also studied using light and, for the first time, scanning electron microscopy. Previously unreported and erroneous morphological features of taxonomic significance are revealed, including the presence of narrow cervical alae, single pair of small, submedial pores and single, short medial ditch on each lip, interlabia with very pointed anterior prolongation, single medio-ventral precloacal papilla on anterior cloacal lip and double paracloacal papillae slightly posterior to cloaca.

A Systemic Small RNA Signaling System in Plants

PubMed Central

Yoo, Byung-Chun; Kragler, Friedrich; Varkonyi-Gasic, Erika; Haywood, Valerie; Archer-Evans, Sarah; Lee, Young Moo; Lough, Tony J.; Lucas, William J.

2004-01-01

Systemic translocation of RNA exerts non-cell-autonomous control over plant development and defense. Long-distance delivery of mRNA has been proven, but transport of small interfering RNA and microRNA remains to be demonstrated. Analyses performed on phloem sap collected from a range of plants identified populations of small RNA species. The dynamic nature of this population was reflected in its response to growth conditions and viral infection. The authenticity of these phloem small RNA molecules was confirmed by bioinformatic analysis; potential targets for a set of phloem small RNA species were identified. Heterografting studies, using spontaneously silencing coat protein (CP) plant lines, also established that transgene-derived siRNA move in the long-distance phloem and initiate CP gene silencing in the scion. Biochemical analysis of pumpkin (Cucurbita maxima) phloem sap led to the characterization of C. maxima Phloem SMALL RNA BINDING PROTEIN1 (CmPSRP1), a unique component of the protein machinery probably involved in small RNA trafficking. Equivalently sized small RNA binding proteins were detected in phloem sap from cucumber (Cucumis sativus) and lupin (Lupinus albus). PSRP1 binds selectively to 25-nucleotide single-stranded RNA species. Microinjection studies provided direct evidence that PSRP1 could mediate the cell-to-cell trafficking of 25-nucleotide single-stranded, but not double-stranded, RNA molecules. The potential role played by PSRP1 in long-distance transmission of silencing signals is discussed with respect to the pathways and mechanisms used by plants to exert systemic control over developmental and physiological processes. PMID:15258266

When the Test of Mediation is More Powerful than the Test of the Total Effect

PubMed Central

O'Rourke, Holly P.; MacKinnon, David P.

2014-01-01

Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase power has not been investigated. First, a study compared analytical power of the mediated effect to the total effect in a single mediator model to identify the situations in which the inclusion of one mediator increased statistical power. Results from the first study indicated that including a mediator increased statistical power in small samples with large coefficients and in large samples with small coefficients, and when coefficients were non-zero and equal across models. Next, a study identified conditions where power was greater for the test of the total mediated effect compared to the test of the total effect in the parallel two mediator model. Results indicated that including two mediators increased power in small samples with large coefficients and in large samples with small coefficients, the same pattern of results found in the first study. Finally, a study assessed analytical power for a sequential (three-path) two mediator model and compared power to detect the three-path mediated effect to power to detect both the test of the total effect and the test of the mediated effect for the single mediator model. Results indicated that the three-path mediated effect had more power than the mediated effect from the single mediator model and the test of the total effect. Practical implications of these results for researchers are then discussed. PMID:24903690

Numerical study on influence of single control surface on aero elastic behavior of forward-swept wing

NASA Astrophysics Data System (ADS)

Wang, Ning; Su, Xinbing; Ma, Binlin; Zhang, Xiaofei

2017-10-01

In order to study the influence of elastic forward-swept wing (FSW) with single control surface, the computational fluid dynamics/computational structural dynamics (CFD/CSD) loose coupling static aero elastic numerical calculation method was adopted for numerical simulation. The effects of the elastic FSW with leading- or trailing-edge control surface on aero elastic characteristics were calculated and analysed under the condition of high subsonic speed. The result shows that, the deflection of every single control surface could change the aero elastic characteristics of elastic FSW greatly. Compared with the baseline model, when leading-edge control surface deflected up, under the condition of small angles of attack, the aerodynamic characteristics was poor, but the bending and torsional deformation decreased. Under the condition of moderate angles of attack, the aerodynamic characteristics was improved, but bending and torsional deformation increased; When leading-edge control surface deflected down, the aerodynamic characteristics was improved, the bending and torsional deformation decreased/increased under the condition of small/moderate angles of attack. Compared with the baseline model, when trailing-edge control surface deflected down, the aerodynamic characteristics was improved. The bending and torsional deformation increased under the condition of small angles of attack. The bending deformation increased under the condition of small angles of attack, but torsional deformation decreases under the condition of moderate angles of attack. So, for the elastic FSW, the deflection of trailing-edge control surface play a more important role on the improvement of aerodynamic and elastic deformation characteristics.

Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

NASA Astrophysics Data System (ADS)

Nichman, Leonid; Järvinen, Emma; Dorsey, James; Connolly, Paul; Duplissy, Jonathan; Fuchs, Claudia; Ignatius, Karoliina; Sengupta, Kamalika; Stratmann, Frank; Möhler, Ottmar; Schnaiter, Martin; Gallagher, Martin

2017-09-01

Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at European Organisation for Nuclear Research (CERN). The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of -30, -40 and -50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition) were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL) measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI). Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE) and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot separate perfectly spherical ice particles from supercooled droplets. Correlation analysis of bulk averaged path depolarisation measurements and single particle measurements of these clouds showed higher R2 values at high concentrations and small diameters, but these results require further confirmation. We find that none of these instruments were able to determine unambiguously the phase of the small particles. These results have implications for the interpretation of atmospheric measurements and parametrisations for modelling, particularly for low particle number concentration clouds.

Repair of long-bone fractures in cats and small dogs with the Unilock mandible locking plate system.

PubMed

Voss, K; Kull, M; Hässig, M; Montavon, P

2009-01-01

To retrospectively evaluate stabilisation of long-bone fractures in cats and small dogs using the Unilock system. Medical histories and radiographs of consecutive patients with long-bone fractures stabilised with the Unilock system were reviewed. Cases with follow-up radiographs taken at least four weeks postoperatively were included. Signalment of the patient, fracture localisation and type, primary fracture repair or revision surgery, single or double plating, and complications for each patient were noted. Additionally, implant size, number of screws, number of cortices engaged with screws, and number of empty holes across the fracture were evaluated in fractures where a single plate had been applied. Eighteen humeral, 18 radial, 20 femoral, and 10 tibial fractures were treated. The Unilock system was used for primary repair in 44 fractures and for revision surgery in 22 fractures. Two plates were applied in 17 fractures, and a single plate was applied in 49 fractures. Follow-up radiographs were taken four to 109 weeks postoperatively. Complications were seen in 12 animals and 13 fractures (19.7%). Fixation failure occurred in seven fractures (10.6%). Cases with a single plate that suffered fixation failure had thinner screws in relation to bone diameter than cases with double plates, and more screws in a main fragment than those without fixation failure. The Unilock system is a suitable implant for fracture fixation of long bones in cats and small dogs.

Processing Research on Chemically Vapor Deposited Silicon Nitride

DTIC Science & Technology

1981-12-01

forming silicon carbide to reduce free silicon content. (b) Boron and aluminum were selected as two single-valence elements with small atomic radii which...obtained in cold wall (CW-3) runs were sliced into small flexure bars (19.1x3.2xt(mm) where t = thickness) if they appeared to be of suitable quality...discussed later. Addition of borcn trichloride in small amounts (Run 8) caused Formation of a light blue translucent deposit which contained at least one

Comprehensive analysis of the HEPN superfamily: identification of novel roles in intra-genomic conflicts, defense, pathogenesis and RNA processing

PubMed Central

2013-01-01

Background The major role of enzymatic toxins that target nucleic acids in biological conflicts at all levels has become increasingly apparent thanks in large part to the advances of comparative genomics. Typically, toxins evolve rapidly hampering the identification of these proteins by sequence analysis. Here we analyze an unexpectedly widespread superfamily of toxin domains most of which possess RNase activity. Results The HEPN superfamily is comprised of all α-helical domains that were first identified as being associated with DNA polymerase β-type nucleotidyltransferases in prokaryotes and animal Sacsin proteins. Using sensitive sequence and structure comparison methods, we vastly extend the HEPN superfamily by identifying numerous novel families and by detecting diverged HEPN domains in several known protein families. The new HEPN families include the RNase LS and LsoA catalytic domains, KEN domains (e.g. RNaseL and Ire1) and the RNase domains of RloC and PrrC. The majority of HEPN domains contain conserved motifs that constitute a metal-independent endoRNase active site. Some HEPN domains lacking this motif probably function as non-catalytic RNA-binding domains, such as in the case of the mannitol repressor MtlR. Our analysis shows that HEPN domains function as toxins that are shared by numerous systems implicated in intra-genomic, inter-genomic and intra-organismal conflicts across the three domains of cellular life. In prokaryotes HEPN domains are essential components of numerous toxin-antitoxin (TA) and abortive infection (Abi) systems and in addition are tightly associated with many restriction-modification (R-M) and CRISPR-Cas systems, and occasionally with other defense systems such as Pgl and Ter. We present evidence of multiple modes of action of HEPN domains in these systems, which include direct attack on viral RNAs (e.g. LsoA and RNase LS) in conjunction with other RNase domains (e.g. a novel RNase H fold domain, NamA), suicidal or dormancy-inducing attack on self RNAs (RM systems and possibly CRISPR-Cas systems), and suicidal attack coupled with direct interaction with phage components (Abi systems). These findings are compatible with the hypothesis on coupling of pathogen-targeting (immunity) and self-directed (programmed cell death and dormancy induction) responses in the evolution of robust antiviral strategies. We propose that altruistic cell suicide mediated by HEPN domains and other functionally similar RNases was essential for the evolution of kin and group selection and cell cooperation. HEPN domains were repeatedly acquired by eukaryotes and incorporated into several core functions such as endonucleolytic processing of the 5.8S-25S/28S rRNA precursor (Las1), a novel ER membrane-associated RNA degradation system (C6orf70), sensing of unprocessed transcripts at the nuclear periphery (Swt1). Multiple lines of evidence suggest that, similar to prokaryotes, HEPN proteins were recruited to antiviral, antitransposon, apoptotic systems or RNA-level response to unfolded proteins (Sacsin and KEN domains) in several groups of eukaryotes. Conclusions Extensive sequence and structure comparisons reveal unexpectedly broad presence of the HEPN domain in an enormous variety of defense and stress response systems across the tree of life. In addition, HEPN domains have been recruited to perform essential functions, in particular in eukaryotic rRNA processing. These findings are expected to stimulate experiments that could shed light on diverse cellular processes across the three domains of life. Reviewers This article was reviewed by Martijn Huynen, Igor Zhulin and Nick Grishin PMID:23768067

Comprehensive analysis of the HEPN superfamily: identification of novel roles in intra-genomic conflicts, defense, pathogenesis and RNA processing.

PubMed

Anantharaman, Vivek; Makarova, Kira S; Burroughs, A Maxwell; Koonin, Eugene V; Aravind, L

2013-06-15

The major role of enzymatic toxins that target nucleic acids in biological conflicts at all levels has become increasingly apparent thanks in large part to the advances of comparative genomics. Typically, toxins evolve rapidly hampering the identification of these proteins by sequence analysis. Here we analyze an unexpectedly widespread superfamily of toxin domains most of which possess RNase activity. The HEPN superfamily is comprised of all α-helical domains that were first identified as being associated with DNA polymerase β-type nucleotidyltransferases in prokaryotes and animal Sacsin proteins. Using sensitive sequence and structure comparison methods, we vastly extend the HEPN superfamily by identifying numerous novel families and by detecting diverged HEPN domains in several known protein families. The new HEPN families include the RNase LS and LsoA catalytic domains, KEN domains (e.g. RNaseL and Ire1) and the RNase domains of RloC and PrrC. The majority of HEPN domains contain conserved motifs that constitute a metal-independent endoRNase active site. Some HEPN domains lacking this motif probably function as non-catalytic RNA-binding domains, such as in the case of the mannitol repressor MtlR. Our analysis shows that HEPN domains function as toxins that are shared by numerous systems implicated in intra-genomic, inter-genomic and intra-organismal conflicts across the three domains of cellular life. In prokaryotes HEPN domains are essential components of numerous toxin-antitoxin (TA) and abortive infection (Abi) systems and in addition are tightly associated with many restriction-modification (R-M) and CRISPR-Cas systems, and occasionally with other defense systems such as Pgl and Ter. We present evidence of multiple modes of action of HEPN domains in these systems, which include direct attack on viral RNAs (e.g. LsoA and RNase LS) in conjunction with other RNase domains (e.g. a novel RNase H fold domain, NamA), suicidal or dormancy-inducing attack on self RNAs (RM systems and possibly CRISPR-Cas systems), and suicidal attack coupled with direct interaction with phage components (Abi systems). These findings are compatible with the hypothesis on coupling of pathogen-targeting (immunity) and self-directed (programmed cell death and dormancy induction) responses in the evolution of robust antiviral strategies. We propose that altruistic cell suicide mediated by HEPN domains and other functionally similar RNases was essential for the evolution of kin and group selection and cell cooperation. HEPN domains were repeatedly acquired by eukaryotes and incorporated into several core functions such as endonucleolytic processing of the 5.8S-25S/28S rRNA precursor (Las1), a novel ER membrane-associated RNA degradation system (C6orf70), sensing of unprocessed transcripts at the nuclear periphery (Swt1). Multiple lines of evidence suggest that, similar to prokaryotes, HEPN proteins were recruited to antiviral, antitransposon, apoptotic systems or RNA-level response to unfolded proteins (Sacsin and KEN domains) in several groups of eukaryotes. Extensive sequence and structure comparisons reveal unexpectedly broad presence of the HEPN domain in an enormous variety of defense and stress response systems across the tree of life. In addition, HEPN domains have been recruited to perform essential functions, in particular in eukaryotic rRNA processing. These findings are expected to stimulate experiments that could shed light on diverse cellular processes across the three domains of life. This article was reviewed by Martijn Huynen, Igor Zhulin and Nick Grishin.

Speed Discrimination: Multiple Stimuli Appear Better Than One

NASA Technical Reports Server (NTRS)

Verghese, Preeti; Stone, Leland S.; Null, Cynthia H. (Technical Monitor)

1995-01-01

We reported that for a 21FC task with multiple moving grating patches (Gabors) in each interval, thresholds for speed discrimination decreased with the number of patches, while increasing the area of a single grating produced no such effect. Furthermore, this decrease occurred regardless of the spacing of the patches about a circle of eccentricity 4 degrees, i.e., whether they were maximally separated or almost touching. These results suggest that it is the multiple, discrete grating patches that cause thresholds to decrease, rather than the spatial arrangement. To test this hypothesis, we measured the effect of dividing a large grating into four quadrants, by superimposing a mean-luminance cross on it. The mean speed discrimination thresholds (Weber Fractions) for four observers were 19, 15, and 11 plus or minus 2%, for the single large grating, the grating with cross, and the 4 maximally-separated, small gratings, respectively. Thus, breaking up a single large grating into multiple parts caused thresholds to improve, despite the fact that less of the original patch was visible. To investigate the possible contribution of total bounding contour length, we measured the effect of coalescing three small grating patches into a single banana-shaped patch, while keeping the total contour length constant. These two conditions were compared to a single, circular Gabor patch of equivalent area that had (necessarily) a smaller contour length. Preliminary data from 3 of 4 observers were similar for the small-grating and banana configurations, but increased for the single, large grating, suggesting that contour length might play a role. We are also investigating the role of low-level factors pertinent to the large grating, such as the pooling of signals from motion units at different eccentricities, and the stimulation of extended inhibitory motion surrounds, as well as the possible contribution of topdown influences that segment the stimulus into distinct objects.

Probing Electron Transfer Mechanisms in Shewanella oneidensis MR-1 using a Nanoelectrode Platform and Single-Cell Imaging

DTIC Science & Technology

2010-01-01

investigate extracellu- lar electron transfer in Shewanella oneidensisMR-1,where an array of nanoholes precludes or single window allows for direct...the single-cell level (Fig. 1B) highlights the re- lative sizes of the nanohole and window openings in the insulating layer deposited over electrodes...relative to individual bacteria such as Shewanella. The nanoholes are sufficiently small to preclude direct contact of the bacterial cell body to the

Corrosion and Passivity Studies with Titanium

DTIC Science & Technology

1955-09-30

the (00.1) Face of a Titanium Single Crystal . - Part 3 Secondary Electron Emission from the Titanium Crystal , and from the Copper-Covered Titanium...ner upon the (00.1) face of a titaniuT single crystal . Low- energy electron diffraction is used to investigate the struc- ture of the deposit. Before...cathode emisaion is strongly dependent on the work function k. 8ince varies with crystal faces and the tip is generally so small that it is a single

Theoretical Studies of Low-Loss Optical Fibers.

DTIC Science & Technology

1980-09-15

on the fiber surface. Single-mode fiber operation is of interest in communications. Marcuse has shown that surface imperfections are a strong source...0.01 very small value of a : 8A at X = 1 vim Marcuse single mode 2.7 typical value of a = 1 jim, A : 10.6 vm, af = 37 Pim surface imperfections 55...Braunstein, "Scattering Losses in Single and Polycrystalline Materials for Infrared Fiber Applications," unpublished. 5. D. Marcuse , "Mode Conversion

Radiosteriometric analysis of movement in the sacroiliac joint during a single-leg stance in patients with long-lasting pelvic girdle pain.

PubMed

Kibsgård, Thomas J; Røise, Olav; Sturesson, Bengt; Röhrl, Stephan M; Stuge, Britt

2014-04-01

Chamberlain's projections (anterior-posterior X-ray of the pubic symphysis) have been used to diagnose sacroiliac joint mobility during the single-leg stance test. This study examined the movement in the sacroiliac joint during the single-leg stance test with precise radiostereometric analysis. Under general anesthesia, tantalum markers were inserted into the dorsal sacrum and the ilium of 11 patients with long-lasting and severe pelvic girdle pain. After two to three weeks, a radiostereometric analysis was conducted while the subjects performed a single-leg stance. Small movements were detected in the sacroiliac joint during the single-leg stance. In both the standing- and hanging-leg sacroiliac join, a total of 0.5 degree rotation was observed; however, no translations were detected. There were no differences in total movement between the standing- and hanging-leg sacroiliac joint. The movement in the sacroiliac joint during the single-leg stance is small and almost undetectable by the precise radiostereometric analysis. A complex movement pattern was seen during the test, with a combination of movements in the two joints. The interpretation of the results of this study is that, the Chamberlain examination likely is inadequate in the examination of sacroiliac joint movement in patients with pelvic girdle pain. Copyright © 2014 Elsevier Ltd. All rights reserved.

Single-row versus double-row arthroscopic rotator cuff repair in small- to medium-sized tears.

PubMed

Aydin, Nuri; Kocaoglu, Baris; Guven, Osman

2010-07-01

Double-row rotator cuff repair leads to superior cuff integrity and clinical results compared with single-row repair. The study enrolled 68 patients with a full-thickness rotator cuff tear who were divided into 2 groups of 34 patients according to repair technique. The patients were followed-up for at least 2 years. The results were evaluated by Constant score. Despite the biomechanical studies and cadaver studies that proved the superiority of double-row fixation over single-row fixation, our clinical results show no difference in functional outcome between the two methods. It is evident that double-row repair is more technically demanding, expensive, and time-consuming than single-row repair, without providing a significant improvement in clinical results. Comparison between groups did not show significant differences. At the final follow-up, the Constant score was 82.2 in the single-row group and 78.8 in the double-row group. Functional outcome was improved in both groups after surgery, but the difference between the 2 groups was not significant. At long-term follow-up, arthroscopic rotator cuff repair with the double-row technique showed no significant difference in clinical outcome compared with single-row repair in small to medium tears. 2010 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Type-I superconductivity in YbSb2 single crystals

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

Zhao, Liang L.; Lausberg, Stefan; Kim, Hyunsoo

2012-06-25

We present evidence of type-I superconductivity in YbSb2 single crystals from dc and ac magnetization, heat capacity, and resistivity measurements. The critical temperature and critical field are determined to be Tc≈ 1.3 K and Hc≈ 55 Oe. A small Ginzburg-Landau parameter κ= 0.05, together with typical magnetization isotherms of type-I superconductors, small critical field values, a strong differential paramagnetic effect signal, and a field-induced change from second- to first-order phase transition, confirms the type-I nature of the superconductivity in YbSb2. A possible second superconducting state is observed in the radio-frequency susceptibility measurements, with Tc(2)≈ 0.41 K and Hc(2)≈ 430 Oe.

Advanced Ring-Shaped Microelectrode Assay Combined with Small Rectangular Electrode for Quasi-In vivo Measurement of Cell-to-Cell Conductance in Cardiomyocyte Network

NASA Astrophysics Data System (ADS)

Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji

2013-06-01

To predict the risk of fatal arrhythmia induced by cardiotoxicity in the highly complex human heart system, we have developed a novel quasi-in vivo electrophysiological measurement assay, which combines a ring-shaped human cardiomyocyte network and a set of two electrodes that form a large single ring-shaped electrode for the direct measurement of irregular cell-to-cell conductance occurrence in a cardiomyocyte network, and a small rectangular microelectrode for forced pacing of cardiomyocyte beating and for acquiring the field potential waveforms of cardiomyocytes. The advantages of this assay are as follows. The electrophysiological signals of cardiomyocytes in the ring-shaped network are superimposed directly on a single loop-shaped electrode, in which the information of asynchronous behavior of cell-to-cell conductance are included, without requiring a set of huge numbers of microelectrode arrays, a set of fast data conversion circuits, or a complex analysis in a computer. Another advantage is that the small rectangular electrode can control the position and timing of forced beating in a ring-shaped human induced pluripotent stem cell (hiPS)-derived cardiomyocyte network and can also acquire the field potentials of cardiomyocytes. First, we constructed the human iPS-derived cardiomyocyte ring-shaped network on the set of two electrodes, and acquired the field potential signals of particular cardiomyocytes in the ring-shaped cardiomyocyte network during simultaneous acquisition of the superimposed signals of whole-cardiomyocyte networks representing cell-to-cell conduction. Using the small rectangular electrode, we have also evaluated the response of the cell network to electrical stimulation. The mean and SD of the minimum stimulation voltage required for pacing (VMin) at the small rectangular electrode was 166+/-74 mV, which is the same as the magnitude of amplitude for the pacing using the ring-shaped electrode (179+/-33 mV). The results showed that the addition of a small rectangular electrode into the ring-shaped electrode was effective for the simultaneous measurement of whole-cell-network signals and single-cell/small-cluster signals on a local site in the cell network, and for the pacing by electrical stimulation of cardiomyocyte networks.

SmallSat Precision Navigation with Low-Cost MEMS IMU Swarms

NASA Technical Reports Server (NTRS)

Christian, John; Bishop, Robert; Martinez, Andres; Petro, Andrew

2015-01-01

The continued advancement of small satellite-based science missions requires the solution to a number of important technical challenges. Of particular note is that small satellite missions are characterized by tight constraints on cost, mass, power, and volume that make them unable to fly the high-quality Inertial Measurement Units (IMUs) required for orbital missions demanding precise orientation and positioning. Instead, small satellite missions typically fly low-cost Micro-Electro-Mechanical System (MEMS) IMUs. Unfortunately, the performance characteristics of these MEMS IMUs make them ineffectual in many spaceflight applications when employed in a single IMU system configuration.

10 CFR 431.444 - Test procedures for the measurement of energy efficiency.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the following test methods: (1) Single-phase small electric motors: either IEEE Std 114, (incorporated...) Polyphase small electric motors less than or equal to 1 horsepower (0.746 kW): IEEE Std 112 (incorporated by... (0.746 kW): IEEE Std 112 (incorporated by reference, see § 431.443), Test Method B. ...

PULSE COUNTER

DOEpatents

Trumbo, D.E.

1959-02-10

A transistorized pulse-counting circuit adapted for use with nuclear radiation detecting detecting devices to provide a small, light weight portable counter is reported. The small size and low power requirements of the transistor are of particular value in this instance. The circuit provides an adjustable count scale with a single transistor which is triggered by the accumulated charge on a storage capacitor.

Monte Carlo calculation of large and small-angle electron scattering in air

NASA Astrophysics Data System (ADS)

Cohen, B. I.; Higginson, D. P.; Eng, C. D.; Farmer, W. A.; Friedman, A.; Grote, D. P.; Larson, D. J.

2017-11-01

A Monte Carlo method for angle scattering of electrons in air that accommodates the small-angle multiple scattering and larger-angle single scattering limits is introduced. The algorithm is designed for use in a particle-in-cell simulation of electron transport and electromagnetic wave effects in air. The method is illustrated in example calculations.

Toward a Singleton Undergraduate Computer Graphics Course in Small and Medium-Sized Colleges

ERIC Educational Resources Information Center

Shesh, Amit

2013-01-01

This article discusses the evolution of a single undergraduate computer graphics course over five semesters, driven by a primary question: if one could offer only one undergraduate course in graphics, what would it include? This constraint is relevant to many small and medium-sized colleges that lack resources, adequate expertise, and enrollment…

76 FR 28214 - UChicago Argonne, LLC, et al.; Notice of Decision on Applications for Duty-Free Entry of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-16

.... Applicant: UChicago Argonne, LLC, Lemont, IL 60439. Instrument: Mythen 1K Detector System. Manufacturer... highly correlated systems. This instrument is unique in that it has a small pixel pitch (50 microns); high detection efficiency, single photon counting with high dynamic range; and a small, lightweight and...

Military Hearing Conservation Workshop Director Handbook,

DTIC Science & Technology

1983-11-01

r HaigCnerainDrctrHnbo (b*T scp -asgnetsorrspniblt.s -:.--3 .’..................................................................an. HSHB-OB November...Approved Hearing Protective Devices and Related Equipment. a. Nonstandard. (NOT APPROVED). (I) Fingers (bi-digital earplugs). - - (2) Palms . (3...a) Single-flange (5-10 percent have different sizes between ears): () extra small (white) - 5 percent (ii) small (green) - 25 percent . oil . 5-26 9

Implementing an Audience-Specific Small-Group Gatekeeper Training Program to Respond to Suicide Risk among College Students: A Case Study

ERIC Educational Resources Information Center

Cimini, M. Dolores; Rivero, Estela M.; Bernier, Joseph E.; Stanley, Judith A.; Murray, Andrea D.; Anderson, Drew A.; Wright, Heidi R.; Bapat, Mona

2014-01-01

Objective: This case study evaluated the effectiveness of an audience-specific, single-session, small-group interactive gatekeeper training program conducted at a large northeastern public university. Participants: Participants were 335 faculty, staff, and students completing gatekeeper training programs tailored to their group needs. Methods:…

"It's Really Making a Difference": How Small-Scale Research Projects Can Enhance Teaching and Learning

ERIC Educational Resources Information Center

Dexter, Barbara; Seden, Roy

2012-01-01

Following an internal evaluation exercise, using Action Research, this paper identifies the positive impact of small-scale research projects on teaching and learning at a single case study UK University. Clear evidence is given of how the projects benefited students and staff, and enhanced institutional culture. Barriers to better practice are…

Outcomes of a Structured Education Intervention for Latinas Concerning Breast Cancer and Mammography

ERIC Educational Resources Information Center

Laughman, Anna Bawtinhimer; Boselli, Danielle; Love, Magbis; Steuerwald, Nury; Symanowski, James; Blackley, Kris; Wheeler, Mellisa; Arevalo, Gustavo; Carrizosa, Daniel; Raghavan, Derek

2017-01-01

Objective: This study examined the utility of living room and church-based small group educational sessions on breast cancer and mammography, for under-served Latinas in North Carolina, USA. Design: Non-randomised, single arm design. Setting: A total of 329 self-selected Latinas participated in 31 small group educational classes in church and home…

77 FR 39125 - Defense Acquisition Regulations System; Defense Federal Acquisition Regulation Supplement; Only...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-29

... resolicitation period has been added to address the application to small business set-asides. The final rule... transactional process time in all cases where only a single offer is received in response to a competitive... requirement, if only one offer is received, has also been added for small business set-asides. c. Requirements...

In Situ Hot-Spot Assembly as a General Strategy for Probing Single Biomolecules.

PubMed

Liu, Huiqiao; Li, Qiang; Li, Mingmin; Ma, Sisi; Liu, Dingbin

2017-05-02

Single-molecule detection using surface-enhanced Raman spectroscopy (SERS) has attracted increasing attention in chemical and biomedical analysis. However, it remains a major challenge to probe single biomolecules by means of SERS hot spots owing to the small volume of hot spots and their random distribution on substrates. We here report an in situ hot-spot assembly method as a general strategy for probing single biomolecules. As a proof-of-concept, this proposed strategy was successfully used for the detection of single microRNA-21 (miRNA-21, a potential cancer biomarker) at the single-cell level, showing great capability in differentiating the expression of miRNA-21 in single cancer cells from normal cells. This approach was further extended to single-protein detection. The versatility of the strategy opens an exciting avenue for single-molecule detection of biomarkers of interest and thus holds great promise in a variety of biological and biomedical applications.

Role-Taking in Small Book-Discussion Groups by First-Grade Boys in a Single-Gender School

ERIC Educational Resources Information Center

Das, Sudarshana

2010-01-01

Gender and achievement is controversial. Social and cultural concerns about who boys are and who they should become is tied closely to how both coeducational and single-gender schools function, and how they approach literacy issues. Currently, there is little understanding of social and cultural influences on students' experiences with discourse…

Bias Corrections for Standardized Effect Size Estimates Used with Single-Subject Experimental Designs

ERIC Educational Resources Information Center

Ugille, Maaike; Moeyaert, Mariola; Beretvas, S. Natasha; Ferron, John M.; Van den Noortgate, Wim

2014-01-01

A multilevel meta-analysis can combine the results of several single-subject experimental design studies. However, the estimated effects are biased if the effect sizes are standardized and the number of measurement occasions is small. In this study, the authors investigated 4 approaches to correct for this bias. First, the standardized effect…

The Media, Marketing, and Single Sex Schooling

ERIC Educational Resources Information Center

Mills, Martin

2004-01-01

The Australian media's interest in education, as in many Anglophone countries, is frequently dominated by concerns about boys in schools. In 2002, in a country region of the Australian State of Queensland, this concern was evident in a debate on the merits of single sex schooling that took place in a small local newspaper. The debate was fuelled…

Single-Chip Microcomputer Control Of The PWM Inverter

NASA Astrophysics Data System (ADS)

Morimoto, Masayuki; Sato, Shinji; Sumito, Kiyotaka; Oshitani, Katsumi

1987-10-01

A single-chip microcomputer-based con-troller for a pulsewidth modulated 1.7 KVA inverter of an airconditioner is presented. The PWM pattern generation and the system control of the airconditioner are achieved by software of the 8-bit single-chip micro-computer. The single-chip microcomputer has the disadvantages of low processing speed and small memory capacity which can be overcome by the magnetic flux control method. The PWM pattern is generated every 90 psec. The memory capacity of the PWM look-up table is less than 2 kbytes. The simple and reliable control is realized by the software-based implementation.

A versatile nanotechnology to connect individual nano-objects for the fabrication of hybrid single-electron devices

NASA Astrophysics Data System (ADS)

Bernand-Mantel, A.; Bouzehouane, K.; Seneor, P.; Fusil, S.; Deranlot, C.; Brenac, A.; Notin, L.; Morel, R.; Petroff, F.; Fert, A.

2010-11-01

We report on the high yield connection of single nano-objects as small as a few nanometres in diameter to separately elaborated metallic electrodes, using a 'table-top' nanotechnology. Single-electron transport measurements validate that transport occurs through a single nano-object. The vertical geometry of the device natively allows an independent choice of materials for each electrode and the nano-object. In addition ferromagnetic materials can be used without encountering oxidation problems. The possibility of elaborating such hybrid nanodevices opens new routes for the democratization of spintronic studies in low dimensions.

Department of Defense Agency Financial Report for FY 2011

DTIC Science & Technology

2011-11-01

in size. They range from the very small (an unoccupied site supporting a single navigational aid that sits on less than one-half acre of land) to...U.S. military presence in Iraq will be zero troops (except for a small number under Chief of Mission authority). 48,770 50,000 46,000 1.2.2...number of pieces of rolling stock in Iraq supporting U.S. military troops, will be zero (except for a small number used by military personnel under

Making RISC.

PubMed

Kawamata, Tomoko; Tomari, Yukihide

2010-07-01

It is well established that 20- to 30-nt small RNAs, including small interfering RNAs, microRNAs and Piwi-interacting RNAs, play crucial roles in regulating gene expression and control a surprisingly diverse array of biological processes. These small RNAs cannot work alone: they must form effector ribonucleoprotein complexes - RNA-induced silencing complexes (RISCs) - to exert their function. Thus, RISC assembly is a key process in small RNA-mediated silencing. Recent biochemical analyses of RISC assembly, together with new structural studies of Argonaute, the core protein component of RISC, suggest a revised view of how mature RISC, which contains single-stranded guide RNA, is built from small RNAs that are born double-stranded. Copyright 2010 Elsevier Ltd. All rights reserved.

Optics-Integrated Microfluidic Platforms for Biomolecular Analyses

PubMed Central

Bates, Kathleen E.; Lu, Hang

2016-01-01

Compared with conventional optical methods, optics implemented on microfluidic chips provide small, and often much cheaper ways to interrogate biological systems from the level of single molecules up to small model organisms. The optical probing of single molecules has been used to investigate the mechanical properties of individual biological molecules; however, multiplexing of these measurements through microfluidics and nanofluidics confers many analytical advantages. Optics-integrated microfluidic systems can significantly simplify sample processing and allow a more user-friendly experience; alignments of on-chip optical components are predetermined during fabrication and many purely optical techniques are passively controlled. Furthermore, sample loss from complicated preparation and fluid transfer steps can be virtually eliminated, a particularly important attribute for biological molecules at very low concentrations. Excellent fluid handling and high surface area/volume ratios also contribute to faster detection times for low abundance molecules in small sample volumes. Although integration of optical systems with classical microfluidic analysis techniques has been limited, microfluidics offers a ready platform for interrogation of biophysical properties. By exploiting the ease with which fluids and particles can be precisely and dynamically controlled in microfluidic devices, optical sensors capable of unique imaging modes, single molecule manipulation, and detection of minute changes in concentration of an analyte are possible. PMID:27119629

Seebeck coefficient of one electron

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

Durrani, Zahid A. K., E-mail: z.durrani@imperial.ac.uk

2014-03-07

The Seebeck coefficient of one electron, driven thermally into a semiconductor single-electron box, is investigated theoretically. With a finite temperature difference ΔT between the source and charging island, a single electron can charge the island in equilibrium, directly generating a Seebeck effect. Seebeck coefficients for small and finite ΔT are calculated and a thermally driven Coulomb staircase is predicted. Single-electron Seebeck oscillations occur with increasing ΔT, as one electron at a time charges the box. A method is proposed for experimental verification of these effects.

Separating and combining single-mode and multimode optical beams

DOEpatents

Ruggiero, Anthony J; Masquelier, Donald A; Cooke, Jeffery B; Kallman, Jeffery S

2013-11-12

Techniques for combining initially separate single mode and multimode optical beams into a single "Dual Mode" fiber optic have been developed. Bi-directional propagation of two beams that are differentiated only by their mode profiles (i.e., wavefront conditions) is provided. The beams can be different wavelengths and or contain different modulation information but still share a common aperture. This method allows the use of conventional micro optics and hybrid photonic packaging techniques to produce small rugged packages suitable for use in industrial or military environments.

Spin properties of charged Mn-doped quantum dota)

NASA Astrophysics Data System (ADS)

Besombes, L.; Léger, Y.; Maingault, L.; Mariette, H.

2007-04-01

The optical properties of individual quantum dots doped with a single Mn atom and charged with a single carrier are analyzed. The emission of the neutral, negatively and positively charged excitons coupled with a single magnetic atom (Mn) are observed in the same individual quantum dot. The spectrum of the charged excitons in interaction with the Mn atom shows a rich pattern attributed to a strong anisotropy of the hole-Mn exchange interaction slightly perturbed by a small valence-band mixing. The anisotropy in the exchange interaction between a single magnetic atom and a single hole is revealed by comparing the emission of a charged Mn-doped quantum dot in longitudinal and transverse magnetic field.

Compartmental genomics in living cells revealed by single-cell nanobiopsy.

PubMed

Actis, Paolo; Maalouf, Michelle M; Kim, Hyunsung John; Lohith, Akshar; Vilozny, Boaz; Seger, R Adam; Pourmand, Nader

2014-01-28

The ability to study the molecular biology of living single cells in heterogeneous cell populations is essential for next generation analysis of cellular circuitry and function. Here, we developed a single-cell nanobiopsy platform based on scanning ion conductance microscopy (SICM) for continuous sampling of intracellular content from individual cells. The nanobiopsy platform uses electrowetting within a nanopipette to extract cellular material from living cells with minimal disruption of the cellular milieu. We demonstrate the subcellular resolution of the nanobiopsy platform by isolating small subpopulations of mitochondria from single living cells, and quantify mutant mitochondrial genomes in those single cells with high throughput sequencing technology. These findings may provide the foundation for dynamic subcellular genomic analysis.

Single-electron thermal noise

NASA Astrophysics Data System (ADS)

Nishiguchi, Katsuhiko; Ono, Yukinori; Fujiwara, Akira

2014-07-01

We report the observation of thermal noise in the motion of single electrons in an ultimately small dynamic random access memory (DRAM). The nanometer-scale transistors that compose the DRAM resolve the thermal noise in single-electron motion. A complete set of fundamental tests conducted on this single-electron thermal noise shows that the noise perfectly follows all the aspects predicted by statistical mechanics, which include the occupation probability, the law of equipartition, a detailed balance, and the law of kT/C. In addition, the counting statistics on the directional motion (i.e., the current) of the single-electron thermal noise indicate that the individual electron motion follows the Poisson process, as it does in shot noise.

Analysis of photogenerated random telegraph signal in single electron detector (photo-SET).

PubMed

Troudi, M; Sghaier, Na; Kalboussi, A; Souifi, A

2010-01-04

In this paper, we analyzed slow single traps, situated inside the tunnel oxide of small area single electron photo-detector (photo-SET or nanopixel). The relationship between excitation signal (photons) and random-telegraph-signal (RTS) was evidenced. We demonstrated that photoinduced RTS observed on a photo-detector is due to the interaction between single photogenerated charges that tunnel from dot to dot and current path. Based on RTS analysis for various temperatures, gate bias and optical power we determined the characteristics of these single photogenerated traps: the energy position within the silicon bandgap, capture cross section and the position within the Si/SiO(x = 1.5) interfaces.

Single-electron thermal noise.

PubMed

Nishiguchi, Katsuhiko; Ono, Yukinori; Fujiwara, Akira

2014-07-11

We report the observation of thermal noise in the motion of single electrons in an ultimately small dynamic random access memory (DRAM). The nanometer-scale transistors that compose the DRAM resolve the thermal noise in single-electron motion. A complete set of fundamental tests conducted on this single-electron thermal noise shows that the noise perfectly follows all the aspects predicted by statistical mechanics, which include the occupation probability, the law of equipartition, a detailed balance, and the law of kT/C. In addition, the counting statistics on the directional motion (i.e., the current) of the single-electron thermal noise indicate that the individual electron motion follows the Poisson process, as it does in shot noise.

Patterns of ecosystem services supply across farm properties: Implications for ecosystem services-based policy incentives.

PubMed

Nahuelhual, Laura; Benra, Felipe; Laterra, Pedro; Marin, Sandra; Arriagada, Rodrigo; Jullian, Cristobal

2018-09-01

In developing countries, the protection of biodiversity and ecosystem services (ES) rests on the hands of millions of small landowners that coexist with large properties, in a reality of highly unequal land distribution. Guiding the effective allocation of ES-based incentives in such contexts requires researchers and practitioners to tackle a largely overlooked question: for a given targeted area, will single large farms or several small ones provide the most ES supply? The answer to this question has important implications for conservation planning and rural development alike, which transcend efficiency to involve equity issues. We address this question by proposing and testing ES supply-area relations (ESSARs) around three basic hypothesized models, characterized by constant (model 1), increasing (model 2), and decreasing increments (model 3) of ES supply per unit of area or ES "productivity". Data to explore ESSARs came from 3384 private landholdings located in southern Chile ranging from 0.5ha to over 30,000ha and indicators of four ES (forage, timber, recreation opportunities, and water supply). Forage provision best fit model 3, which suggests that targeting several small farms to provide this ES should be a preferred choice, as compared to a single large farm. Timber provision best fit model 2, suggesting that in this case targeting a single large farm would be a more effective choice. Recreation opportunities best fit model 1, which indicates that several small or a single large farm of a comparable size would be equally effective in delivering this ES. Water provision fit model 1 or model 2 depending on the study site. The results corroborate that ES provision is not independent from property area and therefore understanding ESSARs is a necessary condition for setting conservation incentives that are both efficient (deliver the highest conservation outcome at the least cost) and fair for landowners. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast Learning with Weak Synaptic Plasticity.

PubMed

Yger, Pierre; Stimberg, Marcel; Brette, Romain

2015-09-30

New sensory stimuli can be learned with a single or a few presentations. Similarly, the responses of cortical neurons to a stimulus have been shown to increase reliably after just a few repetitions. Long-term memory is thought to be mediated by synaptic plasticity, but in vitro experiments in cortical cells typically show very small changes in synaptic strength after a pair of presynaptic and postsynaptic spikes. Thus, it is traditionally thought that fast learning requires stronger synaptic changes, possibly because of neuromodulation. Here we show theoretically that weak synaptic plasticity can, in fact, support fast learning, because of the large number of synapses N onto a cortical neuron. In the fluctuation-driven regime characteristic of cortical neurons in vivo, the size of membrane potential fluctuations grows only as √N, whereas a single output spike leads to potentiation of a number of synapses proportional to N. Therefore, the relative effect of a single spike on synaptic potentiation grows as √N. This leverage effect requires precise spike timing. Thus, the large number of synapses onto cortical neurons allows fast learning with very small synaptic changes. Significance statement: Long-term memory is thought to rely on the strengthening of coactive synapses. This physiological mechanism is generally considered to be very gradual, and yet new sensory stimuli can be learned with just a few presentations. Here we show theoretically that this apparent paradox can be solved when there is a tight balance between excitatory and inhibitory input. In this case, small synaptic modifications applied to the many synapses onto a given neuron disrupt that balance and produce a large effect even for modifications induced by a single stimulus. This effect makes fast learning possible with small synaptic changes and reconciles physiological and behavioral observations. Copyright © 2015 the authors 0270-6474/15/3513351-12$15.00/0.

Single-port laparoscopic and robotic partial nephrectomy.

PubMed

Kaouk, Jihad H; Goel, Raj K

2009-05-01

Partial nephrectomy (PN) for small renal masses provides effective oncologic outcomes. Single-port laparoscopic (SPL) and robotic surgeries are evolving approaches to advance minimally invasive surgery. To determine the feasibility of laparoscopic and robotic single-port PN. Since 2007, evaluation of patients undergoing SPL and single-port robotic (SPR) PN at a primary referral center was performed. Patients with small, solitary, exophytic-enhancing renal masses were selected. Patients with a solitary kidney, endophytic or hilar tumors, and previous abdominal and/or kidney surgery were excluded. Perioperative and pathologic data were entered prospectively into an institutional review board (IRB)-approved database. Tumor location determined either an open Hasson transperitoneal or retroperitoneal approach. A single multichannel port or Triport provided intra-abdominal access. The Harmonic Scalpel was used for tumor excision under normal renal perfusion. The da Vinci surgical robot was used for SPR cases. Patient demographics, perioperative, hematologic, and pathologic data as well as pain assessment using the Visual Analog Pain Scale (VAPS) were assessed. A total of seven patients underwent single-port PN (SPL=5, SPR=2). One patient with a right anterior upper-pole mass required conversion from SPL to standard laparoscopy following tumor excision because of intraoperative bleeding. Pathology revealed six lesions compatible with renal cell carcinoma (RCC) and one benign cyst. One negative frozen section came back focally positive on final histopathology. All other surgical margins were negative. A mean difference of 3.0+/-2.0 g/dl in hemoglobin was noted in all patients. Minimal pain was noted at discharge following both laparoscopic and robotic single-port surgery (VAPS=1.7+/-1.2 vs 1+/-0.5/10). SPL and SPR PN is feasible for select exophytic tumors. Robotics may improve surgical capabilities during single-port surgery.

When the test of mediation is more powerful than the test of the total effect.

PubMed

O'Rourke, Holly P; MacKinnon, David P

2015-06-01

Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase power has not been investigated. To address this deficit, in a first study we compared the analytical power values of the mediated effect and the total effect in a single-mediator model, to identify the situations in which the inclusion of one mediator increased statistical power. The results from this first study indicated that including a mediator increased statistical power in small samples with large coefficients and in large samples with small coefficients, and when coefficients were nonzero and equal across models. Next, we identified conditions under which power was greater for the test of the total mediated effect than for the test of the total effect in the parallel two-mediator model. These results indicated that including two mediators increased power in small samples with large coefficients and in large samples with small coefficients, the same pattern of results that had been found in the first study. Finally, we assessed the analytical power for a sequential (three-path) two-mediator model and compared the power to detect the three-path mediated effect to the power to detect both the test of the total effect and the test of the mediated effect for the single-mediator model. The results indicated that the three-path mediated effect had more power than the mediated effect from the single-mediator model and the test of the total effect. Practical implications of these results for researchers are then discussed.

J-V and C-V investigation of the effect of small molecular fullerene and non-fullerene acceptors for CH3NH3PbI3 perovskite solar cell

NASA Astrophysics Data System (ADS)

Zheng, Yanqiong; Wang, Chao; Yu, Junle; Yang, Fang; Zhang, Jing; Wei, Bin; Li, Weishi

2017-11-01

To find the ideal acceptors for perovskite solar cells (PSCs) and get insight into the dielectric property at the interface between perovskite and acceptor, series of small molecular fullerene and non-fullerene acceptors were comparatively investigated. Fullerene acceptors based PSCs show higher performance than non-fullerene acceptors based PSCs. However, the perylene tetracarboxylic diimide based PSC has achieved a η PCE of 4.70%, implying that it is a promising acceptor candidate for PSCs because of its suitable energy level, high electron mobility, and smooth surface. By employing double acceptors of (6,6)-phenyl-C61-butyric acid methyl ester (PCBM)/C60 or PCBM/3,4,9,10-perylenetetracarboxylic bisbenzimidazole, the PSC stability is greatly improved even without performance enhancement. The perovskite (Pero)/PCBM film shows smooth surface, suggesting that PCBM penetrates into the Pero layer. The hydrophobicity trend of Pero/acceptor composite films is same as the device performance by judging from the water contact angle, and Pero/PCBM as well as Pero/C60 show higher hydrophobicity than other Pero/small-molecular-acceptor composite films. Capacitance-voltage characteristics of the series of single and double acceptor based PSCs were measured. The double acceptor based PSCs show larger depletion layer width (W d) than single acceptor based PSCs. Meanwhile, the defect density (N A) in Pero layer for single acceptor based PSCs is larger than that for double acceptor based PSCs, implying better n-doping of Pero layer by using a single acceptor.

Sequencing of individual chromosomes of plant pathogenic Fusarium oxysporum.

PubMed

Kashiwa, Takeshi; Kozaki, Toshinori; Ishii, Kazuo; Turgeon, B Gillian; Teraoka, Tohru; Komatsu, Ken; Arie, Tsutomu

2017-01-01

A small chromosome in reference isolate 4287 of F. oxysporum f. sp. lycopersici (Fol) has been designated as a 'pathogenicity chromosome' because it carries several pathogenicity related genes such as the Secreted In Xylem (SIX) genes. Sequence assembly of small chromosomes in other isolates, based on a reference genome template, is difficult because of karyotype variation among isolates and a high number of sequences associated with transposable elements. These factors often result in misassembly of sequences, making it unclear whether other isolates possess the same pathogenicity chromosome harboring SIX genes as in the reference isolate. To overcome this difficulty, single chromosome sequencing after Contour-clamped Homogeneous Electric Field (CHEF) separation of chromosomes was performed, followed by de novo assembly of sequences. The assembled sequences of individual chromosomes were consistent with results of probing gels of CHEF separated chromosomes with SIX genes. Individual chromosome sequencing revealed that several SIX genes are located on a single small chromosome in two pathogenic forms of F. oxysporum, beyond the reference isolate 4287, and in the cabbage yellows fungus F. oxysporum f. sp. conglutinans. The particular combination of SIX genes on each small chromosome varied. Moreover, not all SIX genes were found on small chromosomes; depending on the isolate, some were on big chromosomes. This suggests that recombination of chromosomes and/or translocation of SIX genes may occur frequently. Our method improves sequence comparison of small chromosomes among isolates. Copyright © 2016 Elsevier Inc. All rights reserved.

Organisational Learning and HRD: How Appropriate Are They for Small Firms?

ERIC Educational Resources Information Center

Saru, Essi

2007-01-01

Purpose: The purpose of this paper is to study human resource development (HRD) and organisational learning issues in a small expert organisation. Design/methodology/approach: This is a qualitative single case study conducted in one Finnish SME. It is part of an ongoing study. It is descriptive in nature and the aim is to find out whether the…

Monte Carlo calculation of large and small-angle electron scattering in air

DOE PAGES

Cohen, B. I.; Higginson, D. P.; Eng, C. D.; ...

2017-08-12

A Monte Carlo method for angle scattering of electrons in air that accommodates the small-angle multiple scattering and larger-angle single scattering limits is introduced. In this work, the algorithm is designed for use in a particle-in-cell simulation of electron transport and electromagnetic wave effects in air. The method is illustrated in example calculations.

Axial tomography in 3D live cell microscopy

NASA Astrophysics Data System (ADS)

Richter, Verena; Bruns, Sarah; Bruns, Thomas; Piper, Mathis; Weber, Petra; Wagner, Michael; Cremer, Christoph; Schneckenburger, Herbert

2017-07-01

A miniaturized setup for sample rotation on a microscope stage has been developed, combined with light sheet, confocal or structured illumination microscopy and applied to living cells as well as to small organisms. This setup permits axial tomography with improved visualization of single cells or small cell clusters as well as an enhanced effective 3D resolution upon sample rotation.

Gas-Bearing Crucible for Shot Tower

NASA Technical Reports Server (NTRS)

Youngberg, C. L.; Miller, C. G.; Stephens, J. B.; Finnerty, A. A.

1983-01-01

Device protects molten drops from contamination and distortion. Gas flowing through levitator tube levitates small balls while they melt. Gas heated by filament extending through center of tube. Gas bearing crucible on tube has concave configuration to hold single relatively large ball or many recesses to hold many small balls. By time spheres reach foam, they are cooled sufficiently by radiation to retain their shape.

Automatic Mexico Gulf Oil Spill Detection from Radarsat-2 SAR Satellite Data Using Genetic Algorithm

NASA Astrophysics Data System (ADS)

Marghany, Maged

2016-10-01

In this work, a genetic algorithm is exploited for automatic detection of oil spills of small and large size. The route is achieved using arrays of RADARSAT-2 SAR ScanSAR Narrow single beam data obtained in the Gulf of Mexico. The study shows that genetic algorithm has automatically segmented the dark spot patches related to small and large oil spill pixels. This conclusion is confirmed by the receiveroperating characteristic (ROC) curve and ground data which have been documented. The ROC curve indicates that the existence of oil slick footprints can be identified with the area under the curve between the ROC curve and the no-discrimination line of 90%, which is greater than that of other surrounding environmental features. The small oil spill sizes represented 30% of the discriminated oil spill pixels in ROC curve. In conclusion, the genetic algorithm can be used as a tool for the automatic detection of oil spills of either small or large size and the ScanSAR Narrow single beam mode serves as an excellent sensor for oil spill patterns detection and surveying in the Gulf of Mexico.

High Sensitivity Refractometer Based on Reflective Smf-Small Diameter No Core Fiber Structure.

PubMed

Zhou, Guorui; Wu, Qiang; Kumar, Rahul; Ng, Wai Pang; Liu, Hao; Niu, Longfei; Lalam, Nageswara; Yuan, Xiaodong; Semenova, Yuliya; Farrell, Gerald; Yuan, Jinhui; Yu, Chongxiu; Zeng, Jie; Tian, Gui Yun; Fu, Yong Qing

2017-06-16

A high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional single mode fiber (SMF) and the end face of the SDNCF was coated with a thin film of gold to provide reflective light. The influence of SDNCF diameter and length on the refractive index sensitivity of the sensor has been investigated by both simulations and experiments, where results show that the diameter of SDNCF has significant influence. However, SDNCF length has limited influence on the sensitivity. Experimental results show that a sensitivity of 327 nm/RIU (refractive index unit) has been achieved for refractive indices ranging from 1.33 to 1.38, which agrees well with the simulated results with a sensitivity of 349.5 nm/RIU at refractive indices ranging from 1.33 to 1.38.

Ultra-small single-negative electric metamaterials for electromagnetic coupling reduction of microstrip antenna array.

PubMed

Xu, He-Xiu; Wang, Guang-Ming; Qi, Mei-Qing; Zeng, Hui-Yong

2012-09-24

We report initially the design, fabrication and measurement of using waveguided electric metamaterials (MTM) in the design of closely-spaced microtrip antenna arrays with mutual coupling reduction. The complementary spiral ring resonators (CSRs) which exhibit single negative resonant permittivity around 3.5GHz are used as the basic electric MTM element. For verification, two CSRs with two and three concentric rings are considered, respectively. By properly arranging these well engineered waveguided MTMs between two H-plane coupled patch antennas, both numerical and measured results indicate that more than 8.4 dB mutual coupling reduction is obtained. The mechanism has been studied from a physical insight. The electric MTM element is electrically small, enabling the resultant antenna array to exhibit a small separation (λo/8 at the operating wavelength) and thus a high directivity. The proposed strategy opens an avenue to new types of antenna with super performances and can be generalized for other electric resonators.

Prototype design of singles processing unit for the small animal PET

NASA Astrophysics Data System (ADS)

Deng, P.; Zhao, L.; Lu, J.; Li, B.; Dong, R.; Liu, S.; An, Q.

2018-05-01

Position Emission Tomography (PET) is an advanced clinical diagnostic imaging technique for nuclear medicine. Small animal PET is increasingly used for studying the animal model of disease, new drugs and new therapies. A prototype of Singles Processing Unit (SPU) for a small animal PET system was designed to obtain the time, energy, and position information. The energy and position is actually calculated through high precison charge measurement, which is based on amplification, shaping, A/D conversion and area calculation in digital signal processing domian. Analysis and simulations were also conducted to optimize the key parameters in system design. Initial tests indicate that the charge and time precision is better than 3‰ FWHM and 350 ps FWHM respectively, while the position resolution is better than 3.5‰ FWHM. Commination tests of the SPU prototype with the PET detector indicate that the system time precision is better than 2.5 ns, while the flood map and energy spectra concored well with the expected.

Large tubular colonic duplication in an adult treated with a small midline incision

PubMed Central

Yong, Yuen Geng; Jung, Kyung Uk; Cho, Yong Beom; Yun, Seong Hyeon; Kim, Hee Cheol; Lee, Woo Yong

2012-01-01

Tubular colonic duplication presenting in adults is rare and difficult to diagnose preoperatively. Only a few cases have been reported in the literature. We report a case of a 29-year-old lady presenting with a long history of chronic constipation, abdominal mass and repeated episodes of abdominal pain. The abdominal-pelvic computed tomography scan showed segmental bowel wall thickening thought to be small bowel, and dilatation with stasis of intraluminal content. The provisional diagnosis was small bowel duplication. She was scheduled for single port laparoscopic resection. However, a T-shaped tubular colonic duplication at sigmoid colon was found intraoperatively. Resection of the large T-shaped tubular colonic duplication containing multiple impacted large fecaloma and primary anastomosis was performed. There was no perioperative complication. We report, herein, the case of a T-shaped tubular colonic duplication at sigmoid colon in an adult who was successfully treated through mini-laparotomy assisted by single port laparoscopic surgery. PMID:22403754

Simethicone for small bowel preparation for capsule endoscopy: a systematic, single-blinded, controlled study.

PubMed

Albert, Jörg; Göbel, Christa-Maria; Lesske, Joachim; Lotterer, Erich; Nietsch, Hubert; Fleig, Wolfgang E

2004-04-01

Capsule endoscopy is a new imaging method for visualization of the entire small bowel. However, no standardized protocol for bowel preparation for capsule endoscopy has been evaluated. Capsule endoscopy was performed in 36 consecutive patients, all of whom fasted for 12 hours before ingestion of the capsule. Before capsule endoscopy, 18 patients received 80 mg simethicone and 18 had no supplemental medication for bowel preparation. Two observers, both experienced endoscopists, independently reviewed the examinations in a single-blinded and randomly assigned fashion. Mucosal visibility and intraluminal gas bubbles were assessed and graded by both observers. Bowel preparation with simethicone resulted in significantly better visibility because of fewer intraluminal bubbles (p<0.01). Interobserver agreement was excellent (r>/=0.8; k 0.78: 95% CI[0.57, 0.98] ). No adverse effect of simethicone was observed. Simethicone may be added to the routine preparation for capsule endoscopy to improve the visibility of small bowel mucosa.

Combining cell sheet technology and electrospun scaffolding for engineered tubular, aligned, and contractile blood vessels.

PubMed

Rayatpisheh, Shahrzad; Heath, Daniel E; Shakouri, Amir; Rujitanaroj, Pim-On; Chew, Sing Yian; Chan-Park, Mary B

2014-03-01

Herein we combine cell sheet technology and electrospun scaffolding to rapidly generate circumferentially aligned tubular constructs of human aortic smooth muscles cells with contractile gene expression for use as tissue engineered blood vessel media. Smooth muscle cells cultured on micropatterned and N-isopropylacrylamide-grafted (pNIPAm) polydimethylsiloxane (PDMS), a small portion of which was covered by aligned electrospun scaffolding, resulted in a single sheet of unidirectionally aligned cells. Upon cooling to room temperature, the scaffold, its adherent cells, and the remaining cell sheet detached and were collected on a mandrel to generating tubular constructs with circumferentially aligned smooth muscle cells which possess contractile gene expression and a single layer of electrospun scaffold as an analogue to a small diameter blood vessel's internal elastic lamina (IEL). This method improves cell sheet handling, results in rapid circumferential alignment of smooth muscle cells which immediately express contractile genes, and introduction of an analogue to small diameter blood vessel IEL. Copyright © 2013 Elsevier Ltd. All rights reserved.

Single-Cell Semiconductor Sequencing

PubMed Central

Kohn, Andrea B.; Moroz, Tatiana P.; Barnes, Jeffrey P.; Netherton, Mandy; Moroz, Leonid L.

2014-01-01

RNA-seq or transcriptome analysis of individual cells and small-cell populations is essential for virtually any biomedical field. It is especially critical for developmental, aging, and cancer biology as well as neuroscience where the enormous heterogeneity of cells present a significant methodological and conceptual challenge. Here we present two methods that allow for fast and cost-efficient transcriptome sequencing from ultra-small amounts of tissue or even from individual cells using semiconductor sequencing technology (Ion Torrent, Life Technologies). The first method is a reduced representation sequencing which maximizes capture of RNAs and preserves transcripts’ directionality. The second, a template-switch protocol, is designed for small mammalian neurons. Both protocols, from cell/tissue isolation to final sequence data, take up to 4 days. The efficiency of these protocols has been validated with single hippocampal neurons and various invertebrate tissues including individually identified neurons within a simpler memory-forming circuit of Aplysia californica and early (1-, 2-, 4-, 8-cells) embryonic and developmental stages from basal metazoans. PMID:23929110

A Highly Specific Gold Nanoprobe for Live-Cell Single-Molecule Imaging

NASA Astrophysics Data System (ADS)

Leduc, Cécile; Si, Satyabrata; Gautier, Jérémie; Soto-Ribeiro, Martinho; Wehrle-Haller, Bernhard; Gautreau, Alexis; Giannone, Grégory; Cognet, Laurent; Lounis, Brahim

2013-04-01

Single molecule tracking in live cells is the ultimate tool to study subcellular protein dynamics, but it is often limited by the probe size and photostability. Due to these issues, long-term tracking of proteins in confined and crowded environments, such as intracellular spaces, remains challenging. We have developed a novel optical probe consisting of 5-nm gold nanoparticles functionalized with a small fragment of camelid antibodies that recognize widely used GFPs with a very high affinity, which we call GFP-nanobodies. These small gold nanoparticles can be detected and tracked using photothermal imaging for arbitrarily long periods of time. Surface and intracellular GFP-proteins were effectively labeled even in very crowded environments such as adhesion sites and cytoskeletal structures both in vitro and in live cell cultures. These nanobody-coated gold nanoparticles are probes with unparalleled capabilities; small size, perfect photostability, high specificity, and versatility afforded by combination with the vast existing library of GFP-tagged proteins.

Single walled carbon nanotube-based stochastic resonance device with molecular self-noise source

NASA Astrophysics Data System (ADS)

Fujii, Hayato; Setiadi, Agung; Kuwahara, Yuji; Akai-Kasaya, Megumi

2017-09-01

Stochastic resonance (SR) is an intrinsic noise usage system for small-signal sensing found in various living creatures. The noise-enhanced signal transmission and detection system, which is probabilistic but consumes low power, has not been used in modern electronics. We demonstrated SR in a summing network based on a single-walled carbon nanotube (SWNT) device that detects small subthreshold signals with very low current flow. The nonlinear current-voltage characteristics of this SWNT device, which incorporated Cr electrodes, were used as the threshold level of signal detection. The adsorption of redox-active polyoxometalate molecules on SWNTs generated additional noise, which was utilized as a self-noise source. To form a summing network SR device, a large number of SWNTs were aligned parallel to each other between the electrodes, which increased the signal detection ability. The functional capabilities of the present small-size summing network SR device, which rely on dense nanomaterials and exploit intrinsic spontaneous noise at room temperature, offer a glimpse of future bio-inspired electronic devices.

Single fiber model of particle retention in an acoustically driven porous mesh.

PubMed

Grossner, Michael T; Penrod, Alan E; Belovich, Joanne M; Feke, Donald L

2003-03-01

A method for the capture of small particles (tens of microns in diameter) from a continuously flowing suspension has recently been reported. This technique relies on a standing acoustic wave resonating in a rectangular chamber filled with a high-porosity mesh. Particles are retained in this chamber via a complex interaction between the acoustic field and the porous mesh. Although the mesh has a pore size two orders of magnitude larger than the particle diameter, collection efficiencies of 90% have been measured. A mathematical model has been developed to understand the experimentally observed phenomena and to be able to predict filtration performance. By examining a small region (a single fiber) of the porous mesh, the model has duplicated several experimental events such as the focusing of particles near an element of the mesh and the levitation of particles within pores. The single-fiber analysis forms the basis of modeling the overall performance of the particle filtration system. Copyright 2002 Elsevier Science B.V.

A monoclinic, pseudo-orthorhombic Au-Hg mineral of potential economic significance in Pleistocene Snake River alluvial deposits of southeastern Idaho

USGS Publications Warehouse

Desborough, G.A.; Foord, E.E.

1992-01-01

A mineral with the approximate composition of Au94Hg6 - Au88Hg12 (atomic %) has been identified in Pleistocene Snake River alluvial deposits. The gold-mercury mineral occurs as very small grains or as polycrystalline masses composed of subhedral to nearly euhedral attached crystals. Vibratory cold-polishing techniques with 0.05-??m alumina abrasive for polished sections revealed a porous internal texture for most subhedral crystals after 48-72 hours of treatment. Thus, optical character (isotropic or anisotropic) could not be determined by reflected-light microscopy, and pore-free areas were too small for measurement of reflectance. X-ray-diffraction lines rather than individual reflections (spots), on powder camera X-ray films of unrotated spindles of single grains that morphologically appear to be single crystals, indicate that individual subhedral or euhedral crystals are composed of domains in random orientation. Thus, no material was found suitable for single-crystal X-ray diffraction studies. -from Authors

Single-Molecule Imaging Reveals that Small Amyloid-β1–42 Oligomers Interact with the Cellular Prion Protein (PrPC)

PubMed Central

Ganzinger, Kristina A; Narayan, Priyanka; Qamar, Seema S; Weimann, Laura; Ranasinghe, Rohan T; Aguzzi, Adriano; Dobson, Christopher M; McColl, James; St George-Hyslop, Peter; Klenerman, David

2014-01-01

Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer’s disease and have been suggested to induce neurotoxicity by binding to a plethora of cell-surface receptors. However, the heterogeneous mixtures of oligomers of varying sizes and conformations formed by Aβ42 have obscured the nature of the oligomeric species that bind to a given receptor. Here, we have used single-molecule imaging to characterize Aβ42 oligomers (oAβ42) and to confirm the controversial interaction of oAβ42 with the cellular prion protein (PrPC) on live neuronal cells. Our results show that, at nanomolar concentrations, oAβ42 interacts with PrPC and that the species bound to PrPC are predominantly small oligomers (dimers and trimers). Single-molecule biophysical studies can thus aid in deciphering the mechanisms that underlie receptor-mediated oAβ-induced neurotoxicity, and ultimately facilitate the discovery of novel inhibitors of these pathways. PMID:25294384

Counting polymers moving through a single ion channel

NASA Astrophysics Data System (ADS)

Bezrukov, Sergey M.; Vodyanoy, Igor; Parsegian, V. Adrian

1994-07-01

THE change in conductance of a small electrolyte-filled capillary owing to the passage of sub-micrometre-sized particles has long been used for particle counting and sizing. A commercial device for such measurements, the Coulter counter, is able to detect particles of sizes down to several tenths of a micrometre1-3. Nuclepore technology (in which pores are etched particle tracks) has extended the lower limit of size detection to 60-nm particles by using a capillary of diameter 0.45 μm (ref. 4). Here we show that natural channel-forming peptides incorporated into a bilayer lipid membrane can be used to detect the passage of single molecules with gyration radii as small as 5-15 Å. From our experiments with alamethicin pores we infer both the average number and the diffusion coefficients of poly(ethylene glycol) molecules in the pore. Our approach provides a means of observing the statistics and mechanics of flexible polymers moving within the confines of precisely defined single-molecule structures.

Uniting functional network topology and oscillations in the fronto-parietal single unit network of behaving primates.

PubMed

Dann, Benjamin; Michaels, Jonathan A; Schaffelhofer, Stefan; Scherberger, Hansjörg

2016-08-15

The functional communication of neurons in cortical networks underlies higher cognitive processes. Yet, little is known about the organization of the single neuron network or its relationship to the synchronization processes that are essential for its formation. Here, we show that the functional single neuron network of three fronto-parietal areas during active behavior of macaque monkeys is highly complex. The network was closely connected (small-world) and consisted of functional modules spanning these areas. Surprisingly, the importance of different neurons to the network was highly heterogeneous with a small number of neurons contributing strongly to the network function (hubs), which were in turn strongly inter-connected (rich-club). Examination of the network synchronization revealed that the identified rich-club consisted of neurons that were synchronized in the beta or low frequency range, whereas other neurons were mostly non-oscillatory synchronized. Therefore, oscillatory synchrony may be a central communication mechanism for highly organized functional spiking networks.

The Effect of Single Pyramidal Neuron Firing Within Layer 2/3 and Layer 4 in Mouse V1.

PubMed

Meyer, Jochen F; Golshani, Peyman; Smirnakis, Stelios M

2018-01-01

The influence of cortical cell spiking activity on nearby cells has been studied extensively in vitro . Less is known, however, about the impact of single cell firing on local cortical networks in vivo . In a pioneering study, Kwan and Dan (Kwan and Dan, 2012) reported that in mouse layer 2/3 (L2/3), under anesthesia , stimulating a single pyramidal cell recruits ~2.1% of neighboring units. Here we employ two-photon calcium imaging in layer 2/3 of mouse V1, in conjunction with single-cell patch clamp stimulation in layer 2/3 or layer 4, to probe, in both the awake and lightly anesthetized states , how (i) activating single L2/3 pyramidal neurons recruits neighboring units within L2/3 and from layer 4 (L4) to L2/3, and whether (ii) activating single pyramidal neurons changes population activity in local circuit. To do this, it was essential to develop an algorithm capable of quantifying how sensitive the calcium signal is at detecting effectively recruited units ("followers"). This algorithm allowed us to estimate the chance of detecting a follower as a function of the probability that an epoch of stimulation elicits one extra action potential (AP) in the follower cell. Using this approach, we found only a small fraction (<0.75%) of L2/3 cells to be significantly activated within a radius of ~200 μm from a stimulated neighboring L2/3 pyramidal cell. This fraction did not change significantly in the awake vs. the lightly anesthetized state, nor when stimulating L2/3 vs. underlying L4 pyramidal neurons. These numbers are in general agreement with, though lower than, the percentage of neighboring cells (2.1% pyramidal cells and interneurons combined) reported by Kwan and Dan to be activated upon stimulating single L2/3 pyramidal neurons under anesthesia (Kwan and Dan, 2012). Interestingly, despite the small number of individual units found to be reliably driven, we did observe a modest but significant elevation in aggregate population responses compared to sham stimulation. This underscores the distributed impact that single cell stimulation has on neighboring microcircuit responses, revealing only a small minority of relatively strongly connected partners. Patch-clamp stimulation in conjunction with 2-photon imaging shows that activating single layer-2/3 or layer-4 pyramidal neurons produces few (<1% of local units) reliable single-cell followers in L2/3 of mouse area V1, either under light anesthesia or in quiet wakefulness: instead, single cell stimulation was found to elevate aggregate population activity in a weak but highly distributed fashion.

Application of CHESS single-bounce capillaries at synchrotron beamlines

NASA Astrophysics Data System (ADS)

Huang, R.; Szebenyi, T.; Pfeifer, M.; Woll, A.; Smilgies, D.-M.; Finkelstein, K.; Dale, D.; Wang, Y.; Vila-Comamala, J.; Gillilan, R.; Cook, M.; Bilderback, D. H.

2014-03-01

Single-bounce capillaries are achromatic X-ray focusing optics that can provide efficient and high demagnification focusing with large numerical apertures. Capillary fabrication at CHESS can be customized according to specific application requirements. Exemplary applications are reviewed in this paper, as well as recent progress on condensers for high-resolution transmission X-ray microscopy and small focal size capillaries.

Developments in Analytical Chemistry: Acoustically Levitated Drop Reactors for Enzyme Reaction Kinetics and Single-Walled Carbon Nanotube-Based Sensors for Detection of Toxic Organic Phosphonates

ERIC Educational Resources Information Center

Field, Christopher Ryan

2009-01-01

Developments in analytical chemistry were made using acoustically levitated small volumes of liquid to study enzyme reaction kinetics and by detecting volatile organic compounds in the gas phase using single-walled carbon nanotubes. Experience gained in engineering, electronics, automation, and software development from the design and…

A Generalized Least Squares Regression Approach for Computing Effect Sizes in Single-Case Research: Application Examples

ERIC Educational Resources Information Center

Maggin, Daniel M.; Swaminathan, Hariharan; Rogers, Helen J.; O'Keeffe, Breda V.; Sugai, George; Horner, Robert H.

2011-01-01

A new method for deriving effect sizes from single-case designs is proposed. The strategy is applicable to small-sample time-series data with autoregressive errors. The method uses Generalized Least Squares (GLS) to model the autocorrelation of the data and estimate regression parameters to produce an effect size that represents the magnitude of…

Characterization of the complete chloroplast genome of Platycarya strobilacea (Juglandaceae)

Treesearch

Jing Yan; Kai Han; Shuyun Zeng; Peng Zhao; Keith Woeste; Jianfang Li; Zhan-Lin Liu

2017-01-01

The whole chloroplast genome (cp genome) sequence of Platycarya strobilacea was characterized from Illumina pair-end sequencing data. The complete cp genome was 160,994 bp in length and contained a large single copy region (LSC) of 90,225 bp and a small single copy region (SSC) of 18,371 bp, which were separated by a pair of inverted repeat regions...

On the Deficiencies of the Ferricinium-Ferrocene Redox Couple for Estimating Transfer Energies of Single Ions.

DTIC Science & Technology

1980-08-15

breakdown of the "ferrocene assumption" for estimating the transfer thermodynamics of single ions. I 4 Experimental Most solvents were Aldrich " Gold ...solvent "donor number" DN1 6 (Table I). A similar finding has been noted previously for monoatomic cations. 1 5 The small negative value of - Sc+) in water

Simulating cut-to-length harvesting operations in Appalachian hardwoods

Treesearch

Jingxin Wang; Chris B. LeDoux; Yaoxiang Li

2005-01-01

Cut-to-length (CTL) harvesting systems involving small and large harvesters and a forwarder were simulated using a modular computer simulation model. The two harvesters simulated were a modified John Deere 988 tracked excavator with a single grip sawhead and a Timbco T425 based excavator with a single grip sawhead. The forwarder used in the simulations was a Valmet 524...

Intermittency in a single event

NASA Astrophysics Data System (ADS)

Bialas, A.; Ziaja, B.

1996-02-01

The possibility to study intermittency in a single event of high multiplicity is investigated in the framework of the α-model. It is found that, for cascade long enough, the dispersion of intermittency exponents obtained from individual events is fairly small. This fact opens the possibility to study the distribution of the intermittency parameters characterizing the cascades seen (by observing intermittency) in particle spectra.

Fully Bayesian Estimation of Data from Single Case Designs

ERIC Educational Resources Information Center

Rindskopf, David

2013-01-01

Single case designs (SCDs) generally consist of a small number of short time series in two or more phases. The analysis of SCDs statistically fits in the framework of a multilevel model, or hierarchical model. The usual analysis does not take into account the uncertainty in the estimation of the random effects. This not only has an effect on the…

77 FR 74022 - Notice of Proposed Information Collection: Comment Request; Ginnie Mae Mortgage-Backed Securities...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-12

... multiple Issuer MBS is structured so that small issuers, who do not meet the minimum number of loans and... program, securities are backed by single-family or multifamily loans. Under the Ginnie Mae II program, securities are only backed by single family loans. Both the Ginnie Mae I and II MBS are modified pass-through...

Single-mode annular chirally-coupled core fibers for fiber lasers

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Hao, He; He, Linlu; Gong, Mali

2018-03-01

Chirally-coupled core (CCC) fiber can transmit single fundamental mode and effectively suppresses higher-order mode (HOM) propagation, thus improve the beam quality. However, the manufacture of CCC fiber is complicated due to its small side core. To decrease the manufacture difficulty in China, a novel fiber structure is presented, defined as annular chirally-coupled core (ACCC) fiber, replacing the small side core by a larger side annulus. In this paper, we designed the fiber parameters of this new structure, and demonstrated that the new structure has a similar property of single mode with traditional CCC fiber. Helical coordinate system was introduced into the finite element method (FEM) to analyze the mode field in the fiber, and the beam propagation method (BPM) was employed to analyze the influence of the fiber parameters on the mode loss. Based on the result above, the fiber structure was optimized for efficient single-mode transmission, in which the core diameter is 35 μm with beam quality M2 value of 1.04 and an optical to optical conversion efficiency of 84%. In this fiber, fundamental mode propagates in an acceptable loss, while the HOMs decay rapidly.

Nanokit for single-cell electrochemical analyses.

PubMed

Pan, Rongrong; Xu, Mingchen; Jiang, Dechen; Burgess, Jame D; Chen, Hong-Yuan

2016-10-11

The development of more intricate devices for the analysis of small molecules and protein activity in single cells would advance our knowledge of cellular heterogeneity and signaling cascades. Therefore, in this study, a nanokit was produced by filling a nanometer-sized capillary with a ring electrode at the tip with components from traditional kits, which could be egressed outside the capillary by electrochemical pumping. At the tip, femtoliter amounts of the kit components were reacted with the analyte to generate hydrogen peroxide for the electrochemical measurement by the ring electrode. Taking advantage of the nanotip and small volume injection, the nanokit was easily inserted into a single cell to determine the intracellular glucose levels and sphingomyelinase (SMase) activity, which had rarely been achieved. High cellular heterogeneities of these two molecules were observed, showing the significance of the nanokit. Compared with the current methods that use a complicated structural design or surface functionalization for the recognition of the analytes, the nanokit has adapted features of the well-established kits and integrated the kit components and detector in one nanometer-sized capillary, which provides a specific device to characterize the reactivity and concentrations of cellular compounds in single cells.

A meta-analysis of single case research studies on aided augmentative and alternative communication systems with individuals with autism spectrum disorders.

PubMed

Ganz, Jennifer B; Earles-Vollrath, Theresa L; Heath, Amy K; Parker, Richard I; Rispoli, Mandy J; Duran, Jaime B

2012-01-01

Many individuals with autism cannot speak or cannot speak intelligibly. A variety of aided augmentative and alternative communication (AAC) approaches have been investigated. Most of the research on these approaches has been single-case research, with small numbers of participants. The purpose of this investigation was to meta-analyze the single case research on the use of aided AAC with individuals with autism spectrum disorders (ASD). Twenty-four single-case studies were analyzed via an effect size measure, the Improvement Rate Difference (IRD). Three research questions were investigated concerning the overall impact of AAC interventions on targeted behavioral outcomes, effects of AAC interventions on individual targeted behavioral outcomes, and effects of three types of AAC interventions. Results indicated that, overall, aided AAC interventions had large effects on targeted behavioral outcomes in individuals with ASD. AAC interventions had positive effects on all of the targeted behavioral outcome; however, effects were greater for communication skills than other categories of skills. Effects of the Picture Exchange Communication System and speech-generating devices were larger than those for other picture-based systems, though picture-based systems did have small effects.

Effects of single caging and cage size on behavior and stress level of domestic neutered cats housed in an animal shelter.

PubMed

Uetake, Katsuji; Goto, Akihiro; Koyama, Rumi; Kikuchi, Rieko; Tanaka, Toshio

2013-03-01

Cats need a minimum amount of space even in animal shelters. In this study the effects of single caging and cage size on the behavior and stress level of domestic cats were investigated. Six neutered cats (2-15 years old) that had been housed in a group for at least 7 months were moved to three kinds of single cages (small, medium and large) by rotation on a Latin square design. They experienced each cage size for 6 days. Cats could use vertical dimensions when housed in a group room and the large cage. Behavioral observation was conducted for 3 h in the evening, and stress levels were assessed by urine cortisol-to-creatinine ratios. The amounts (estimated proportions) of time spent in locomotion and social/solitary play were lower even in large cages than in group housing (both P < 0.05). Conversely, the amount of time spent resting tended to increase when housed singly (P = 0.104). The urine cortisol-to-creatinine ratios of singly housed cats tended to be higher than that of group-housed cats (P = 0.086). The results indicate that cats become less active when they are housed singly in cages regardless of the cage size. Cats seem to feel no undue stress even in small cages if the stay is short. © 2012 The Authors. Animal Science Journal © 2012 Japanese Society of Animal Science.