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1

Photoacoustic micro-imaging of focused ultrasound induced blood-brain-barrier opening in a rat model  

NASA Astrophysics Data System (ADS)

Blood brain barrier (BBB) prevents most of the drug from transmitting into the brain tissue and decreases the treatment performance for brain disease. One of the methods to overcome the difficulty of drug delivery is to locally increase the permeability of BBB with high-intensity focused ultrasound. In this study, we have investigated the feasibility of photoacoustic microscopy of focused-ultrasound induced BBB opening in a rat model in vivo with gold nanorods (AuNRs) as a contrast agent. This study takes advantage of the strong near-infrared absorption of AuNRs and their extravasation tendency from BBB opening foci due to their nano-scale size. Before the experiments, craniotomy was performed on rats to provide a path for focused ultrasound beam. Localized BBB opening at the depth of about 3 mm from left cortex of rat brains was achieved by delivering 1.5 MHz focused ultrasound energy into brain tissue in the presence of microbubbles. PEGylated AuNRs with a peak optical absorption at ~800 nm were then intravenously administered. Pre-scan prior to BBB disruption and AuNR injection was taken to mark the signal background. After injection, the distribution of AuNRs in rat brains was monitored up to 2 hours. Experimental results show that imaging AuNRs reveals BBB disruption area in left brains while there are no changes observed in the right brains. From our results, photoacoustic imaging plus AuNRs shows the promise as a novel monitoring strategy in identifying the location and variation of focused-ultrasound BBB-opening in a rat model.

Wang, Po-Hsun; Hsu, Po-Hung; Liu, Hao-Li; Wang, Churng-Ren Chris; Li, Meng-Lin

2010-02-01

2

Targeted drug delivery with focused ultrasound-induced blood-brain barrier opening using acoustically-activated nanodroplets.  

PubMed

Focused ultrasound (FUS) in the presence of systemically administered microbubbles has been shown to locally, transiently and reversibly increase the permeability of the blood-brain barrier (BBB), thus allowing targeted delivery of therapeutic agents in the brain for the treatment of central nervous system diseases. Currently, microbubbles are the only agents that have been used to facilitate the FUS-induced BBB opening. However, they are constrained within the intravascular space due to their micron-size diameters, limiting the delivery effect at or near the microvessels. In the present study, acoustically-activated nanodroplets were used as a new class of contrast agents to mediate FUS-induced BBB opening in order to study the feasibility of utilizing these nanoscale phase-shift particles for targeted drug delivery in the brain. Significant dextran delivery was achieved in the mouse hippocampus using nanodroplets at clinically relevant pressures. Passive cavitation detection was used in the attempt to establish a correlation between the amount of dextran delivered in the brain and the acoustic emission recorded during sonication. Conventional microbubbles with the same lipid shell composition and perfluorobutane core as the nanodroplets were also used to compare the efficiency of an FUS-induced dextran delivery. It was found that nanodroplets had a higher BBB opening pressure threshold but a lower stable cavitation threshold than microbubbles, suggesting that contrast agent-dependent acoustic emission monitoring was needed. A more homogeneous dextran delivery within the targeted hippocampus was achieved using nanodroplets without inducing inertial cavitation or compromising safety. Our results offered a new means of developing the FUS-induced BBB opening technology for potential extravascular targeted drug delivery in the brain, extending the potential drug delivery region beyond the cerebral vasculature. PMID:24096019

Chen, Cherry C; Sheeran, Paul S; Wu, Shih-Ying; Olumolade, Oluyemi O; Dayton, Paul A; Konofagou, Elisa E

2013-12-28

3

Nakagami imaging for detecting thermal lesions induced by high-intensity focused ultrasound in tissue.  

PubMed

High-intensity focused ultrasound induces focalized tissue coagulation by increasing the tissue temperature in a tight focal region. Several methods have been proposed to monitor high-intensity focused ultrasound-induced thermal lesions. Currently, ultrasound imaging techniques that are clinically used for monitoring high-intensity focused ultrasound treatment are standard pulse-echo B-mode ultrasound imaging, ultrasound temperature estimation, and elastography-based methods. On the contrary, the efficacy of two-dimensional Nakagami parametric imaging based on the distribution of the ultrasound backscattered signals to quantify properties of soft tissue has recently been evaluated. In this study, ultrasound radio frequency echo signals from ex vivo tissue samples were acquired before and after high-intensity focused ultrasound exposures and then their Nakagami parameter and scaling parameter of Nakagami distribution were estimated. These parameters were used to detect high-intensity focused ultrasound-induced thermal lesions. Also, the effects of changing the acoustic power of the high-intensity focused ultrasound transducer on the Nakagami parameters were studied. The results obtained suggest that the Nakagami distribution's scaling and Nakagami parameters can effectively be used to detect high-intensity focused ultrasound-induced thermal lesions in tissue ex vivo. These parameters can also be used to understand the degree of change in tissue caused by high-intensity focused ultrasound exposures, which could be interpreted as a measure of degree of variability in scatterer concentration in various parts of the high-intensity focused ultrasound lesion. PMID:24264647

Rangraz, Parisa; Behnam, Hamid; Tavakkoli, Jahan

2014-01-01

4

Focused ultrasound induced blood-brain barrier disruption to enhance chemotherapeutic drugs (BCNU) delivery for glioblastoma treatment  

NASA Astrophysics Data System (ADS)

Focused ultrasound has been recently found to capable of temporally and reversibly disrupt local blood-brain barrier (BBB) and opens new frontier in delivering varies type of drugs into brain for central nerve system (CNS) disorder treatment. In this study, we aim to investigate the feasibility of delivering 1, 3-bits (2-chloroethyl) -1-nitrosourea (BCNU) to treat glioblastoma in animal models and evaluate whether this approach would gain treatment efficacy. Under the presence of microbubbles administration, a 400-kHz focused ultrasound was employed to deliver burst-tone ultrasonic energy stimulation to disrupt BBB in animal brains transcranially, and in-vivo monitored by magnetic-resonance imaging (MRI). C6-glioma cells were cultured and implanted into Sprague-Dawley rats as the brain-tumor model. BCNU deposited in brain was quantified by using high-performance liquid chromatography (HPLC), and brain tissues were examined histologically. MRI was employed to longitudinal evaluate the brain tumor treatment including the analysis of tumor progression and animal survival. We confirmed that the focused ultrasound, under the secure ultrasonic energy level, can significantly enhance the BCNU penetration through BBB over 300% than control without cause hemorrhage. Apparent improvement of treatment efficacy achieved by combining focused ultrasound with BCNU delivery, including significant suppression of tumor growth and a prolonged animal survival. This study highly support that this treatment strategy could be clinically-relevant and may help to provide another potential strategy in increasing local chemotherapeutic drugs for brain-tumor treatment.

Liu, Hao-Li; Hua, Mu-Yi; Chen, Pin-Yuan; Huang, Chiung-Yin; Wang, Jiun-Jie; Wei, Kuo-Chen

2010-03-01

5

Feasibility of optoacoustic visualization of high-intensity focused ultrasound-induced thermal lesions in live tissue  

PubMed Central

A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which could operate at 755 nm and 1064 nm, was used to illuminate excised tissue and mice using a bifurcated fiber bundle resulting in two wide beams of light. Tomographic images were obtained while the specimens were rotated within a sphere outlined by a concave arc-shaped array of 64 piezo-composite transducers. These images were then combined to reconstruct 3-D volume images (voxel resolution 0.5 mm), which were acquired before and after HIFU exposure. In vivo optoacoustic images acquired at 1064 nm provided visualization of HIFU lesions. The lesion was indicated by a negative optoacoustic contrast. The molecular nature of such contrast may possibly be associated with reduction of the optical absorption due to reduced concentration of blood, tissue dehydration, denaturation of proteins and porphyrins, and reduction of thermoacoustic efficiency in the thermally treated tissue. These preliminary results demonstrate the potential of optoacoustic imaging to assess and monitor the progress of HIFU therapy.

Chitnis, Parag V.; Brecht, Hans-Peter; Su, Richard; Oraevsky, Alexander A.

2010-01-01

6

Feasibility of optoacoustic visualization of high-intensity focused ultrasound-induced thermal lesions in live tissue.  

PubMed

A 3-D optoacoustic imaging system was used to visualize thermal lesions produced in vivo using high-intensity focused ultrasound (HIFU). A 7.5-MHz, surgical, focused transducer with a radius of curvature of 35 mm and an aperture diameter of 23 mm was used to generate HIFU. A pulsed laser, which could operate at 755 nm and 1064 nm, was used to illuminate excised tissue and mice using a bifurcated fiber bundle resulting in two wide beams of light. Tomographic images were obtained while the specimens were rotated within a sphere outlined by a concave arc-shaped array of 64 piezo-composite transducers. These images were then combined to reconstruct 3-D volume images (voxel resolution 0.5 mm), which were acquired before and after HIFU exposure. In vivo optoacoustic images acquired at 1064 nm provided visualization of HIFU lesions. The lesion was indicated by a negative optoacoustic contrast. The molecular nature of such contrast may possibly be associated with reduction of the optical absorption due to reduced concentration of blood, tissue dehydration, denaturation of proteins and porphyrins, and reduction of thermoacoustic efficiency in the thermally treated tissue. These preliminary results demonstrate the potential of optoacoustic imaging to assess and monitor the progress of HIFU therapy. PMID:20459235

Chitnis, Parag V; Brecht, Hans-Peter; Su, Richard; Oraevsky, Alexander A

2010-01-01

7

Permeability assessment of the focused ultrasound-induced blood-brain barrier opening using dynamic contrast-enhanced MRI  

NASA Astrophysics Data System (ADS)

Focused ultrasound (FUS) in conjunction with microbubbles has been shown to successfully open the blood-brain barrier (BBB) in the mouse brain. In this study, we compute the BBB permeability after opening in vivo. The spatial permeability of the BBB-opened region was assessed using dynamic contrast-enhanced MRI (DCE-MRI). The DCE-MR images were post-processed using the general kinetic model (GKM) and the reference region model (RRM). Permeability maps were generated and the Ktrans values were calculated for a predefined volume of interest in the sonicated and the control area for each mouse. The results demonstrated that Ktrans in the BBB-opened region (0.02 ± 0.0123 for GKM and 0.03 ± 0.0167 min-1 for RRM) was at least two orders of magnitude higher when compared to the contra-lateral (control) side (0 and 8.5 × 10-4 ± 12 × 10-4 min-1, respectively). The permeability values obtained with the two models showed statistically significant agreement and excellent correlation (R2 = 0.97). At histological examination, it was concluded that no macroscopic damage was induced. This study thus constitutes the first permeability assessment of FUS-induced BBB opening using DCE-MRI, supporting the fact that the aforementioned technique may constitute a safe, non-invasive and efficacious drug delivery method.

Vlachos, F.; Tung, Y.-S.; Konofagou, E. E.

2010-09-01

8

Pressure and microbubble size dependence study of focused ultrasound-induced blood-brain barrier opening reversibility in vivo  

NASA Astrophysics Data System (ADS)

Most currently available therapeutic compounds cannot cross the blood-brain barrier (BBB), and their delivery to the brain remains a critical impediment. Focused Ultrasound (FUS) in conjunction with systemically administered microbubbles has been shown to open the BBB locally, non-invasively and reversibly. In this study, we investigated the dependence of BBB opening's reversibility timeline on the peak-rarefactional pressure (PRP) varied from 0.30 MPa to 0.60 MPa and the microbubble size in mice in vivo. The microbubbles used were monodispersed with diameters of 1-2, 4-5 or 6-8 microns. The contrast agent's (Gd) diffusion was used to quantify the opening, in T1-weighted high resolution MR images acquired on the day of sonication and up to five days thereafter. The volume of opening was found to increase with both pressure and microbubble diameter. The duration required for closing was found to be proportional to the volume of opening on the day of opening, and ranged from 24 hours, for the 1-2 um and 0.45 MPa, to 5 days for the 6-8 um and higher PRPs. Overall, larger bubbles did not show significant differences, and the BBB-opened region reduced steadily and radially towards the focal region until complete reinstatement was achieved.

Samiotaki, Gesthimani; Vlachos, Fotios; Tung, Yao-Sheng; Feshitan, Jameel; Borden, Mark; Konofagou, Elisa E.

2012-10-01

9

Quantitative observation of focused-ultrasound-induced vascular leakage and deformation via fluorescein angiography and optical coherence tomography.  

PubMed

Focused ultrasound (FUS) is a recently discovered noninvasive technique for local and temporal enhancement of vascular permeability, which facilitates drug delivery from the vessels into the surrounding tissue. However, exposure to FUS at a high intensity may cause permanent damage. To investigate the effects of the FUS treatment on blood vessels, we propose to use fluorescein angiography (FA) and optical coherence tomography (OCT) for real-time observation of the diffusion of fluorescence dye from blood vessels and to evaluate the morphological changes of the vessels in vivo. With time-resolved FA imaging, the relationship between the exposed power and the improved permeability of the vessels can be assessed according to the enhancement of the fluorescent intensity due to the dye leakage. Furthermore, the variation of the time-resolved fluorescent intensities can be used to identify the occurrence of dye leakage. In contrast, OCT can be implemented for the reconstruction of tissue microstructures. To quantitatively evaluate the morphological changes of the vessels after the FUS exposure with OCT, a new algorithm was proposed to estimate the vessel area based on the comparison of backscattering properties resulting from the tissue and vascular structures. Results showed that the vessel area increased as the exposed power increased, and the area became significantly larger at a higher FUS exposure power of 10 W. In conclusion, integrated FA and OCT observation can be potentially effective for monitoring the outcome and investigating the effects of FUS treatment. PMID:23812607

Tsai, Meng-Tsan; Lee, Cheng-Kuang; Lin, Kung-Min; Lin, Yu-Xiang; Lin, Tzu-Han; Chang, Ting-Chia; Lee, Jiann-Der; Liu, Hao-Li

2013-01-01

10

Focused Ultrasound-Induced Blood-Brain Barrier Opening to Enhance Temozolomide Delivery for Glioblastoma Treatment: A Preclinical Study  

PubMed Central

The purpose of this study is to assess the preclinical therapeutic efficacy of magnetic resonance imaging (MRI)-monitored focused ultrasound (FUS)-induced blood-brain barrier (BBB) disruption to enhance Temozolomide (TMZ) delivery for improving Glioblastoma Multiforme (GBM) treatment. MRI-monitored FUS with microbubbles was used to transcranially disrupt the BBB in brains of Fisher rats implanted with 9L glioma cells. FUS-BBB opening was spectrophotometrically determined by leakage of dyes into the brain, and TMZ was quantitated in cerebrospinal fluid (CSF) and plasma by LC-MS\\MS. The effects of treatment on tumor progression (by MRI), animal survival and brain tissue histology were investigated. Results demonstrated that FUS-BBB opening increased the local accumulation of dyes in brain parenchyma by 3.8-/2.1-fold in normal/tumor tissues. Compared to TMZ alone, combined FUS treatment increased the TMZ CSF/plasma ratio from 22.7% to 38.6%, reduced the 7-day tumor progression ratio from 24.03 to 5.06, and extended the median survival from 20 to 23 days. In conclusion, this study provided preclinical evidence that FUS BBB-opening increased the local concentration of TMZ to improve the control of tumor progression and animal survival, suggesting its clinical potential for improving current brain tumor treatment.

Wei, Kuo-Chen; Chu, Po-Chun; Wang, Hay-Yan Jack; Huang, Chiung-Yin; Chen, Pin-Yuan; Tsai, Hong-Chieh; Lu, Yu-Jen; Lee, Pei-Yun; Tseng, I-Chou; Feng, Li-Ying; Hsu, Peng-Wei; Yen, Tzu-Chen; Liu, Hao-Li

2013-01-01

11

In vivo transcranial cavitation threshold detection during ultrasound-induced blood-brain barrier opening in mice  

PubMed Central

The in vivo cavitation response associated with blood–brain barrier (BBB) opening as induced by transcranial focused ultrasound (FUS) in conjunction with microbubbles was studied in order to better identify the underlying mechanism in its noninvasive application. A cylindrically focused hydrophone, confocal with the FUS transducer, was used as a passive cavitation detector (PCD) to identify the threshold of inertial cavitation (IC) in the presence of Definity® microbubbles (mean diameter range: 1.1–3.3 ?m, Lantheus Medical Imaging, MA, USA). A vessel phantom was first used to determine the reliability of the PCD prior to in vivo use. A cerebral blood vessel was simulated by generating a cylindrical channel of 610 ?m in diameter inside a polyacrylamide gel and by saturating its volume with microbubbles. The microbubbles were sonicated through an excised mouse skull. Second, the same PCD setup was employed for in vivo noninvasive (i.e. transdermal and transcranial) cavitation detection during BBB opening. After the intravenous administration of Definity® microbubbles, pulsed FUS was applied (frequency: 1.525 or 1.5 MHz, peak-rarefactional pressure: 0.15–0.60 MPa, duty cycle: 20%, PRF: 10 Hz, duration: 1 min with a 30 s interval) to the right hippocampus of twenty-six (n = 26) mice in vivo through intact scalp and skull. T1 and T2-weighted MR images were used to verify the BBB opening. A spectrogram was generated at each pressure in order to detect the IC onset and duration. The threshold of BBB opening was found to be at a 0.30 MPa peak-rarefactional pressure in vivo. Both the phantom and in vivo studies indicated that the IC pressure threshold had a peak-rarefactional amplitude of 0.45 MPa. This indicated that BBB opening may not require IC at or near the threshold. Histological analysis showed that BBB opening could be induced without any cellular damage at 0.30 and 0.45 MPa. In conclusion, the cavitation response could be detected without craniotomy in mice and IC may not be required for BBB opening at relatively low pressures.

Tung, Yao-Sheng; Vlachos, Fotios; Choi, James J; Deffieux, Thomas; Selert, Kirsten; Konofagou, Elisa E

2014-01-01

12

In vivo transcranial cavitation threshold detection during ultrasound-induced blood-brain barrier opening in mice  

NASA Astrophysics Data System (ADS)

The in vivo cavitation response associated with blood-brain barrier (BBB) opening as induced by transcranial focused ultrasound (FUS) in conjunction with microbubbles was studied in order to better identify the underlying mechanism in its noninvasive application. A cylindrically focused hydrophone, confocal with the FUS transducer, was used as a passive cavitation detector (PCD) to identify the threshold of inertial cavitation (IC) in the presence of Definity® microbubbles (mean diameter range: 1.1-3.3 µm, Lantheus Medical Imaging, MA, USA). A vessel phantom was first used to determine the reliability of the PCD prior to in vivo use. A cerebral blood vessel was simulated by generating a cylindrical channel of 610 µm in diameter inside a polyacrylamide gel and by saturating its volume with microbubbles. The microbubbles were sonicated through an excised mouse skull. Second, the same PCD setup was employed for in vivo noninvasive (i.e. transdermal and transcranial) cavitation detection during BBB opening. After the intravenous administration of Definity® microbubbles, pulsed FUS was applied (frequency: 1.525 or 1.5 MHz, peak-rarefactional pressure: 0.15-0.60 MPa, duty cycle: 20%, PRF: 10 Hz, duration: 1 min with a 30 s interval) to the right hippocampus of twenty-six (n = 26) mice in vivo through intact scalp and skull. T1 and T2-weighted MR images were used to verify the BBB opening. A spectrogram was generated at each pressure in order to detect the IC onset and duration. The threshold of BBB opening was found to be at a 0.30 MPa peak-rarefactional pressure in vivo. Both the phantom and in vivo studies indicated that the IC pressure threshold had a peak-rarefactional amplitude of 0.45 MPa. This indicated that BBB opening may not require IC at or near the threshold. Histological analysis showed that BBB opening could be induced without any cellular damage at 0.30 and 0.45 MPa. In conclusion, the cavitation response could be detected without craniotomy in mice and IC may not be required for BBB opening at relatively low pressures.

Tung, Yao-Sheng; Vlachos, Fotios; Choi, James J.; Deffieux, Thomas; Selert, Kirsten; Konofagou, Elisa E.

2010-10-01

13

Paramagnetic perfluorocarbon-filled albumin-(Gd-DTPA) microbubbles for the induction of focused-ultrasound-induced blood-brain barrier opening and concurrent MR and ultrasound imaging.  

PubMed

This paper presents new albumin-shelled Gd-DTPA microbubbles (MBs) that can concurrently serve as a dual-modality contrast agent for ultrasound (US) imaging and magnetic resonance (MR) imaging to assist blood-brain barrier (BBB) opening and detect intracerebral hemorrhage (ICH) during focused ultrasound brain drug delivery. Perfluorocarbon-filled albumin-(Gd-DTPA) MBs were prepared with a mean diameter of 2320 nm and concentration of 2.903×10(9) MBs ml(-1) using albumin-(Gd-DTPA) and by sonication with perfluorocarbon (C(3)F(8)) gas. The albumin-(Gd-DTPA) MBs were then centrifuged and the procedure was repeated until the free Gd(3+) ions were eliminated (which were detected by the xylenol orange sodium salt solution). The albumin-(Gd-DTPA) MBs were also characterized and evaluated both in vitro and in vivo by US and MR imaging. Focused US was used with the albumin-(Gd-DTPA) MBs to induce disruption of the BBB in 18 rats. BBB disruption was confirmed with contrast-enhanced T(1)-weighted turbo-spin-echo sequence MR imaging. Heavy T(2)*-weighted 3D fast low-angle shot sequence MR imaging was used to detect ICH. In vitro US imaging experiments showed that albumin-(Gd-DTPA) MBs can significantly enhance the US contrast in T(1)-, T(2)- and T(2)*-weighted MR images. The r(1) and r(2) relaxivities for Gd-DTPA were 7.69 and 21.35 s(-1)mM(-1), respectively, indicating that the MBs represent a positive contrast agent in T(1)-weighted images. In vivo MR imaging experiments on 18 rats showed that focused US combined with albumin-(Gd-DTPA) MBs can be used to both induce disruption of the BBB and detect ICH. To compare the signal intensity change between pure BBB opening and BBB opening accompanying ICH, albumin-(Gd-DTPA) MB imaging can provide a ratio of 5.14 with significant difference (p = 0.026), whereas Gd-DTPA imaging only provides a ratio of 2.13 and without significant difference (p = 0.108). The results indicate that albumin-(Gd-DTPA) MBs have potential as a US/MR dual-modality contrast agent for BBB opening and differentiating focused-US-induced BBB opening from ICH, and can monitor the focused ultrasound brain drug delivery process. PMID:22510713

Liao, Ai-Ho; Liu, Hao-Li; Su, Chia-Hao; Hua, Mu-Yi; Yang, Hung-Wei; Weng, Yu-Ting; Hsu, Po-Hung; Huang, Sheng-Min; Wu, Shih-Yen; Wang, Hsin-Ell; Yen, Tzu-Chen; Li, Pai-Chi

2012-05-01

14

High-Intensity Focused Ultrasound-Induced, Localized Mild Hyperthermia to Enhance Anti-cancer Efficacy of Systemic Doxorubicin: An Experimental Study.  

PubMed

The aim of this study was to evaluate the enhancement of the efficacy of systemic doxorubicin by pulsed high-intensity focused ultrasound (HIFU)-induced, localized mild hyperthermia. For the in vitro study, the intranuclear uptake of doxorubicin by squamous cell carcinoma (SCC)-7 cells incubated at different temperatures was compared. For the in vivo study, mice with SCC-7 tumors were assigned to either the control, conventional hyperthermia, HIFU hyperthermia, doxorubicin-alone, conventional hyperthermia + doxorubicin or HIFU hyperthermia + doxorubicin group. Conventional hyperthermia was induced by immersing the tumor in warm water (42.5°C), and HIFU hyperthermia was induced by HIFU after optimizing the parameters with direct temperature measurements (frequency = 1 MHz, pulse repetition frequency = 5 Hz, power = 12 W, duty cycle = 50%). In the in vitro study, fluorescence was more intense at 42°C than at 37°C and was time dependent. In the in vivo study, tumor growth in the HIFU hyperthermia + doxorubicin group was most prominently suppressed with the highest apoptotic index compared with all other groups (p < 0.05). Pulsed HIFU-induced localized mild hyperthermia enhanced the anti-cancer efficacy of systemic doxorubicin more than conventional mild hyperthermia. PMID:24642222

Chae, Sun Young; Kim, Young-Sun; Park, Min Jung; Yang, Jehoon; Park, Hajan; Namgung, Mi-Sun; Rhim, Hyunchul; Lim, Hyo Keun

2014-07-01

15

Noninvasive localized delivery of Herceptin to the mouse brain by MRI-guided focused ultrasound-induced blood-brain barrier disruption  

NASA Astrophysics Data System (ADS)

Antibody-based anticancer agents are promising chemotherapeutic agents. Among these agents, Herceptin (trastuzumab), a humanized anti-human epidermal growth factor receptor 2 (HER2/c-erbB2) monoclonal antibody, has been used successfully in patients with breast cancer. However, in patients with brain metastasis, the blood-brain barrier limits its use, and a different delivery method is needed to treat these patients. Here, we report that Herceptin can be delivered locally and noninvasively into the mouse central nervous system through the blood-brain barrier under image guidance by using an MRI-guided focused ultrasound blood-brain barrier disruption technique. The amount of Herceptin delivered to the target tissue was correlated with the extent of the MRI-monitored barrier opening, making it possible to estimate indirectly the amount of Herceptin delivered. Histological changes attributable to this procedure were minimal. This method may represent a powerful technique for the delivery of macromolecular agents such as antibodies to treat patients with diseases of the central nervous system. brain tumor | microbubble

Kinoshita, Manabu; McDannold, Nathan; Jolesz, Ferenc A.; Hynynen, Kullervo

2006-08-01

16

Gold-nanorod contrast-enhanced photoacoustic micro-imaging of focused-ultrasound induced blood-brain-barrier opening in a rat model  

NASA Astrophysics Data System (ADS)

In this study, we develop a novel photoacoustic imaging technique based on gold nanorods (AuNRs) for quantitatively monitoring focused-ultrasound (FUS) induced blood-brain barrier (BBB) opening in a rat model in vivo. This study takes advantage of the strong near-infrared absorption (peak at ~800 nm) of AuNRs and the extravasation tendency from BBB opening foci due to their nano-scale size to passively label the BBB disruption area. Experimental results show that AuNR contrast-enhanced photoacoustic microscopy (PAM) successfully reveals the spatial distribution and temporal response of BBB disruption area in the rat brains. The quantitative measurement of contrast enhancement has potential to estimate the local concentration of AuNRs and even the dosage of therapeutic molecules when AuNRs are further used as nano-carrier for drug delivery or photothermal therapy. The photoacoustic results also provide complementary information to MRI, being helpful to discover more details about FUS induced BBB opening in small animal models.

Wang, Po-Hsun; Liu, Hao-Li; Hsu, Po-Hung; Lin, Chia-Yu; Chris Wang, Churng-Ren; Chen, Pin-Yuan; Wei, Kuo-Chen; Yen, Tzu-Chen; Li, Meng-Lin

2012-06-01

17

Pharmacodynamic Analysis of Magnetic Resonance Imaging-Monitored Focused Ultrasound-Induced Blood-Brain Barrier Opening for Drug Delivery to Brain Tumors  

PubMed Central

Microbubble-enhanced focused ultrasound (FUS) can enhance the delivery of therapeutic agents into the brain for brain tumor treatment. The purpose of this study was to investigate the influence of brain tumor conditions on the distribution and dynamics of small molecule leakage into targeted regions of the brain after FUS-BBB opening. A total of 34 animals were used, and the process was monitored by 7T-MRI. Evans blue (EB) dye as well as Gd-DTPA served as small molecule substitutes for evaluation of drug behavior. EB was quantified spectrophotometrically. Spin-spin (R1) relaxometry and area under curve (AUC) were measured by MRI to quantify Gd-DTPA. We found that FUS-BBB opening provided a more significant increase in permeability with small tumors. In contrast, accumulation was much higher in large tumors, independent of FUS. The AUC values of Gd-DTPA were well correlated with EB delivery, suggesting that Gd-DTPA was a good indicator of total small-molecule accumulation in the target region. The peripheral regions of large tumors exhibited similar dynamics of small-molecule leakage after FUS-BBB opening as small tumors, suggesting that FUS-BBB opening may have the most significant permeability-enhancing effect on tumor peripheral. This study provides useful information toward designing an optimized FUS-BBB opening strategy to deliver small-molecule therapeutic agents into brain tumors.

Chu, Po-Chun; Chai, Wen-Yen; Hsieh, Han-Yi; Wang, Jiun-Jie; Wey, Shiaw-Pyng; Huang, Chiung-Yin; Wei, Kuo-Chen; Liu, Hao-Li

2013-01-01

18

Gold-nanorod contrast-enhanced photoacoustic micro-imaging of focused-ultrasound induced blood-brain-barrier opening in a rat model.  

PubMed

In this study, we develop a novel photoacoustic imaging technique based on gold nanorods (AuNRs) for quantitatively monitoring focused-ultrasound (FUS) induced blood-brain barrier (BBB) opening in a rat model in vivo. This study takes advantage of the strong near-infrared absorption (peak at ? 800 nm) of AuNRs and the extravasation tendency from BBB opening foci due to their nano-scale size to passively label the BBB disruption area. Experimental results show that AuNR contrast-enhanced photoacoustic microscopy (PAM) successfully reveals the spatial distribution and temporal response of BBB disruption area in the rat brains. The quantitative measurement of contrast enhancement has potential to estimate the local concentration of AuNRs and even the dosage of therapeutic molecules when AuNRs are further used as nano-carrier for drug delivery or photothermal therapy. The photoacoustic results also provide complementary information to MRI, being helpful to discover more details about FUS induced BBB opening in small animal models. PMID:22734752

Wang, Po-Hsun; Liu, Hao-Li; Hsu, Po-Hung; Lin, Chia-Yu; Wang, Churng-Ren Chris; Chen, Pin-Yuan; Wei, Kuo-Chen; Yen, Tzu-Chen; Li, Meng-Lin

2012-06-01

19

Improved astigmatic focus error detection method  

NASA Technical Reports Server (NTRS)

All easy-to-implement focus- and track-error detection methods presently used in magneto-optical (MO) disk drives using pre-grooved media suffer from a side effect known as feedthrough. Feedthrough is the unwanted focus error signal (FES) produced when the optical head is seeking a new track, and light refracted from the pre-grooved disk produces an erroneous FES. Some focus and track-error detection methods are more resistant to feedthrough, but tend to be complicated and/or difficult to keep in alignment as a result of environmental insults. The astigmatic focus/push-pull tracking method is an elegant, easy-to-align focus- and track-error detection method. Unfortunately, it is also highly susceptible to feedthrough when astigmatism is present, with the worst effects caused by astigmatism oriented such that the tangential and sagittal foci are at 45 deg to the track direction. This disclosure outlines a method to nearly completely eliminate the worst-case form of feedthrough due to astigmatism oriented 45 deg to the track direction. Feedthrough due to other primary aberrations is not improved, but performance is identical to the unimproved astigmatic method.

Bernacki, Bruce E.

1992-01-01

20

Landing airplanes, detecting traffic, and dark focus.  

PubMed

Misjudgments of position in flight and failures to detect other airborne traffic are casualties of the eternal tug-of-war between visible texture and the pilot's dark focus. The eye is lazy and resists the pull of a distant stimulus, preferring to rest at a relatively short focal distance, as it does in the dark or when looking at the sky. Judgments of apparent size are highly correlated with visual accommodation distance, and the difficulty of detecting airplanes on stationary collision courses is greatly aggravated when focus is trapped by structure close to the eyes. Subject, cockpit design, task, and environment variables all interact to determine what we think we see. PMID:7150159

Roscoe, S N

1982-10-01

21

Vibration detection using focus analysis of interferograms.  

PubMed

This paper proposed an automated technique for vibration detection using statistical focus measure to evaluate interferogram contrast. An interferogram sequence from a Mach-Zehnder interferometer setup is recorded (frame rate: 24 fps) and the gray-level variance (GLVA) is plotted versus time. Occurrence of induced vibration in the setup causes a decrease in the interferogram contrast which, in turn, manifests as an evident rapid drop in the variance plot. The technique is demonstrated experimentally using periodic microvibrations (frequency range, ?6 Hz) and aperiodic disturbances. PMID:22441491

Filipinas, Jae Lord Dexter C; Almoro, Percival F

2012-03-20

22

Controlled Ultrasound-Induced Blood-Brain Barrier Disruption Using Passive Acoustic Emissions Monitoring  

PubMed Central

The ability of ultrasonically-induced oscillations of circulating microbubbles to permeabilize vascular barriers such as the blood-brain barrier (BBB) holds great promise for noninvasive targeted drug delivery. A major issue has been a lack of control over the procedure to ensure both safe and effective treatment. Here, we evaluated the use of passively-recorded acoustic emissions as a means to achieve this control. An acoustic emissions monitoring system was constructed and integrated into a clinical transcranial MRI-guided focused ultrasound system. Recordings were analyzed using a spectroscopic method that isolates the acoustic emissions caused by the microbubbles during sonication. This analysis characterized and quantified harmonic oscillations that occur when the BBB is disrupted, and broadband emissions that occur when tissue damage occurs. After validating the system's performance in pilot studies that explored a wide range of exposure levels, the measurements were used to control the ultrasound exposure level during transcranial sonications at 104 volumes over 22 weekly sessions in four macaques. We found that increasing the exposure level until a large harmonic emissions signal was observed was an effective means to ensure BBB disruption without broadband emissions. We had a success rate of 96% in inducing BBB disruption as measured by in contrast-enhanced MRI, and we detected broadband emissions in less than 0.2% of the applied bursts. The magnitude of the harmonic emissions signals was significantly (P<0.001) larger for sonications where BBB disruption was detected, and it correlated with BBB permeabilization as indicated by the magnitude of the MRI signal enhancement after MRI contrast administration (R2?=?0.78). Overall, the results indicate that harmonic emissions can be a used to control focused ultrasound-induced BBB disruption. These results are promising for clinical translation of this technology.

Arvanitis, Costas D.; Livingstone, Margaret S.; Vykhodtseva, Natalia; McDannold, Nathan

2012-01-01

23

Effect of modulated ultrasound parameters on ultrasound-induced thrombolysis  

NASA Astrophysics Data System (ADS)

The potential of ultrasound to enhance enzyme-mediated thrombolysis by application of constant operating parameters (COP) has been widely demonstrated. In this study, the effect of ultrasound with modulated operating parameters (MOP) on enzyme-mediated thrombolysis was investigated. The MOP protocol was applied to an in vitro model of thrombolysis. The results were compared to a COP with the equivalent soft tissue thermal index (TIS) over the duration of ultrasound exposure of 30 min (p < 0.14). To explore potential differences in the mechanism responsible for ultrasound-induced thrombolysis, a perfusion model was used to measure changes in average fibrin pore size of clot before, after and during exposure to MOP and COP protocols and cavitational activity was monitored in real time for both protocols using a passive cavitation detection system. The relative lysis enhancement by each COP and MOP protocol compared to alteplase alone yielded values of 33.69 ± 12.09% and 63.89 ± 15.02% in a thrombolysis model, respectively (p < 0.007). Both COP and MOP protocols caused an equivalent significant increase in average clot pore size of 2.09 × 10-2 ± 0.01 µm and 1.99 × 10-2 ± 0.004 µm, respectively (p < 0.74). No signatures of inertial or stable cavitation were observed for either acoustic protocol. In conclusion, due to mechanisms other than cavitation, application of ultrasound with modulated operating parameters has the potential to significantly enhance the relative lysis enhancement compared to application of ultrasound with constant operating parameters.

Soltani, Azita; Volz, Kim R.; Hansmann, Doulas R.

2008-12-01

24

A Feed-forward Neural Network Algorithm to Detect Thermal Lesions Induced by High Intensity Focused Ultrasound in Tissue.  

PubMed

Non-invasive ultrasound surgeries such as high intensity focused ultrasound have been developed to treat tumors or to stop bleeding. In this technique, incorporation of a suitable imaging modality to monitor and control the treatments is essential so several imaging methods such as X-ray, Magnetic resonance imaging and ultrasound imaging have been proposed to monitor the induced thermal lesions. Currently, the only ultrasound imaging technique that is clinically used for monitoring this treatment is standard pulse-echo B-mode ultrasound imaging. This paper describes a novel method for detecting high intensity focused ultrasound-induced thermal lesions using a feed forward neural-network. This study was carried on in vitro animal tissue samples. Backscattered radio frequency signals were acquired in real-time during treatment in order to detect induced thermal lesions. Changes in various tissue properties including tissue's attenuation coefficient, integrated backscatter, scaling parameter of Nakagami distribution, frequency dependent scatterer amplitudes and tissue vibration derived from the backscattered radio frequency data acquired 10 minutes after treatment regarding to before treatment were used in this study. These estimated parameters were used as features of the neural network. Estimated parameters of two sample tissues including two thermal lesions and their segmented B-mode images were used along with the pathological results as training data for the neural network. The results of the study shows that the trained feed forward neural network could effectively detect thermal lesions in vitro. Comparing the estimated size of the thermal lesion (9.6 mm × 8.5 mm) using neural network with the actual size of that from physical examination (10.1 mm × 9 mm) shows that we could detect high intensity focused ultrasound thermal lesions with the difference of 0.5 mm × 0.5 mm. PMID:23724369

Rangraz, Parisa; Behnam, Hamid; Shakhssalim, Naser; Tavakkoli, Jahan

2012-10-01

25

A Feed-forward Neural Network Algorithm to Detect Thermal Lesions Induced by High Intensity Focused Ultrasound in Tissue  

PubMed Central

Non-invasive ultrasound surgeries such as high intensity focused ultrasound have been developed to treat tumors or to stop bleeding. In this technique, incorporation of a suitable imaging modality to monitor and control the treatments is essential so several imaging methods such as X-ray, Magnetic resonance imaging and ultrasound imaging have been proposed to monitor the induced thermal lesions. Currently, the only ultrasound imaging technique that is clinically used for monitoring this treatment is standard pulse-echo B-mode ultrasound imaging. This paper describes a novel method for detecting high intensity focused ultrasound-induced thermal lesions using a feed forward neural-network. This study was carried on in vitro animal tissue samples. Backscattered radio frequency signals were acquired in real-time during treatment in order to detect induced thermal lesions. Changes in various tissue properties including tissue's attenuation coefficient, integrated backscatter, scaling parameter of Nakagami distribution, frequency dependent scatterer amplitudes and tissue vibration derived from the backscattered radio frequency data acquired 10 minutes after treatment regarding to before treatment were used in this study. These estimated parameters were used as features of the neural network. Estimated parameters of two sample tissues including two thermal lesions and their segmented B-mode images were used along with the pathological results as training data for the neural network. The results of the study shows that the trained feed forward neural network could effectively detect thermal lesions in vitro. Comparing the estimated size of the thermal lesion (9.6 mm × 8.5 mm) using neural network with the actual size of that from physical examination (10.1 mm × 9 mm) shows that we could detect high intensity focused ultrasound thermal lesions with the difference of 0.5 mm × 0.5 mm.

Rangraz, Parisa; Behnam, Hamid; Shakhssalim, Naser; Tavakkoli, Jahan

2012-01-01

26

LESIONS OF ULTRASOUND-INDUCED LUNG HEMORRHAGE ARE NOT CONSISTENT WITH THERMAL INJURY  

PubMed Central

Thermal injury, a potential mechanism of ultrasound-induced lung hemorrhage, was studied by comparing lesions induced by an infrared laser (a tissue-heating source) with those induced by pulsed ultrasound. A 600-mW continuous-wave CO2 laser (wavelength ?10.6 ?m) was focused (680-?m beamwidth) on the surface of the lungs of rats for a duration between 10 to 40 s; ultrasound beamwidths were between 310 and 930 ?m. After exposure, lungs were examined grossly and then processed for microscopic evaluation. Grossly, lesions induced by laser were somewhat similar to those induced by ultrasound; however, microscopically, they were dissimilar. Grossly, lesions were oval, red to dark red and extended into subjacent tissue to form a cone. The surface was elevated, but the center of the laser-induced lesions was often depressed. Microscopically, the laser-induced injury consisted of coagulation of tissue, cells and fluids, whereas injury induced by ultrasound consisted solely of alveolar hemorrhage. These results suggest that ultrasound-induced lung injury is most likely not caused by a thermal mechanism.

Zachary, James F.; Blue, James P.; Miller, Rita J.; Ricconi, Brian J.; Eden, J. Gary; O'Brien, William D.

2007-01-01

27

Focused Synthetic Microwave Array for Mine Detection and Imaging.  

National Technical Information Service (NTIS)

This report presents the results of a contract performed to evaluate the feasibility of a proposed focused synthetic rectangular array for microwave detection and imaging of mines. The proposed technique uses a bistatic antenna system with transmitter and...

W. J. Graham

1991-01-01

28

Ultrasound-induced release of micropallets with cells  

PubMed Central

Separation of selected adherent live cells attached on an array of microelements, termed micropallets, from a mixed population is an important process in biomedical research. We demonstrated that adherent cells can be safely, selectively, and rapidly released from the glass substrate together with micropallets using an ultrasound wave. A 3.3-MHz ultrasound transducer was used to release micropallets (500??m?×?500??m?×?300??m) with attached HeLa cells, and a cell viability of 92% was obtained after ultrasound release. The ultrasound-induced release process was recorded by a high-speed camera, revealing a proximate velocity of ?0.5?m/s.

Guo, Sijia; Wang, Yuli; Allbritton, Nancy; Jiang, Xiaoning

2012-01-01

29

Multifocus image fusion scheme using focused region detection and multiresolution  

NASA Astrophysics Data System (ADS)

To solve the fusion problem of the multifocus images of the same scene, a novel algorithm based on focused region detection and multiresolution is proposed. In order to integrate the advantages of spatial domain-based fusion methods and transformed domain-based fusion methods, we use a technique of focused region detection and a new fusion method of multiscale transform (MST) to guide pixel combination. Firstly, the initial fused image is acquired with a novel multiresolution image fusion method. The pixels of the original images, which are similar to the corresponding initial fused image pixels, are considered to be located in the sharply focused regions. By this method, the initial focused regions can be determined, and the techniques of morphological opening and closing are employed for post-processing. Then the pixels within the focused regions in each source image are selected as the pixels of the fused image; meanwhile, the initial fused image pixels which are located at the focused border regions are retained as the pixels of the final fused image. The fused image is then obtained. The experimental results show that the proposed fusion approach is effective and performs better in fusing multi-focus images than some current methods.

Chai, Yi; Li, Huafeng; Li, Zhaofei

2011-09-01

30

Attention focusing and anomaly detection in systems monitoring  

NASA Technical Reports Server (NTRS)

Any attempt to introduce automation into the monitoring of complex physical systems must start from a robust anomaly detection capability. This task is far from straightforward, for a single definition of what constitutes an anomaly is difficult to come by. In addition, to make the monitoring process efficient, and to avoid the potential for information overload on human operators, attention focusing must also be addressed. When an anomaly occurs, more often than not several sensors are affected, and the partially redundant information they provide can be confusing, particularly in a crisis situation where a response is needed quickly. The focus of this paper is a new technique for attention focusing. The technique involves reasoning about the distance between two frequency distributions, and is used to detect both anomalous system parameters and 'broken' causal dependencies. These two forms of information together isolate the locus of anomalous behavior in the system being monitored.

Doyle, Richard J.

1994-01-01

31

Preface to the focus issue: chaos detection methods and predictability.  

PubMed

This Focus Issue presents a collection of papers originating from the workshop Methods of Chaos Detection and Predictability: Theory and Applications held at the Max Planck Institute for the Physics of Complex Systems in Dresden, June 17-21, 2013. The main aim of this interdisciplinary workshop was to review comprehensively the theory and numerical implementation of the existing methods of chaos detection and predictability, as well as to report recent applications of these techniques to different scientific fields. The collection of twelve papers in this Focus Issue represents the wide range of applications, spanning mathematics, physics, astronomy, particle accelerator physics, meteorology and medical research. This Preface surveys the papers of this Issue. PMID:24985454

Gottwald, Georg A; Skokos, Charalampos

2014-06-01

32

Effective parameters for ultrasound-induced in vivo neurostimulation.  

PubMed

Ultrasound-induced neurostimulation has recently gained increasing attention, but little is known about the mechanisms by which it affects neural activity or about the range of acoustic parameters and stimulation protocols that elicit responses. We have established conditions for transcranial stimulation of the nervous system in vivo, using the mouse somatomotor response. We report that (1) continuous-wave stimuli are as effective as or more effective than pulsed stimuli in eliciting responses, and responses are elicited with stimulus onset rather than stimulus offset; (2) stimulation success increases as a function of both acoustic intensity and acoustic duration; (3) interactions of intensity and duration suggest that successful stimulation results from the integration of stimulus amplitude over a time interval of 50 to 150 ms; and (4) the motor response elicited appears to be an all-or-nothing phenomenon, meaning stronger stimulus intensities and durations increase the probability of a motor response without affecting the duration or strength of the response. PMID:23219040

King, Randy L; Brown, Julian R; Newsome, William T; Pauly, Kim Butts

2013-02-01

33

Characterization of ultrasound-induced pulmonary capillary hemorrhage in rats.  

PubMed

Routine pulmonary ultrasound for diagnosis of disease or injury relies on interpretation of image features, such as comet-tail artifacts, which can also be indicative of the poorly understood phenomenon of ultrasound-induced pulmonary capillary hemorrhage (PCH). Evans blue extraction and bronchoalveolar lavage (BAL) were evaluated for assessment of PCH induced by ultrasound scanning. Rats anesthetized with ketamine with or without xylazine received sham or scanning for 5min with a 7.6MHz linear array. Evans blue extraction and BAL albumin measurements failed to demonstrate significant increases for scanning, even though the induction of comet-tail artifacts was significant. BAL cell counts had an insignificant increase relative to shams at a near-threshold mechanical index (MI) of 0.52 (P=0.07), but a highly significant increase at MI=0.9 (P=0.001). The possibility of xylazine-induced elevated albumin was tested, but no significant decrease was found for sham or scanned rats with ketamine-only anesthesia. Interestingly, without xylazine, the widths of comet-tail artifacts in the ultrasound images were significantly smaller (P=0.001) and cell counts in BAL fluid also were reduced (P=0.014). The BAL cell-count method provides a valuable additional means of PCH quantification. PMID:24583360

Miller, Douglas L; Suresh, M V; Dou, Chunyan; Yu, B; Raghavendran, Krishnan

2014-05-01

34

Relativistic electron beams detection in a dense plasma focus  

NASA Astrophysics Data System (ADS)

Fast electron beams into a hollow anode of a small plasma focus machine (2 kJ, 4 ?F) were measured. The diagnostic method designed for this purpose is founded in a small Rogowski coil introduced into a cavity performed in the anode. By means of this, electron beam pulses of about 10 ns width generated in the plasma focus are detected. Simultaneously, hard X-ray signals obtained from a scintillator-photomultiplier system are registered. The electron beam energy was measured through the time-of-flight of the electrons between probe and anode top. The beams are found to be relativistic and its energy is into the range of hard X-rays energy. An analysis of signal intensities and relative delays for three hundred shots are here presented.

Pouzo, J.; Acuña, H.; Milanese, M.; Moroso, R.

2002-10-01

35

Computer-assisted detection of epileptiform focuses on SPECT images  

NASA Astrophysics Data System (ADS)

Epilepsy is a common nervous system disease often related to consciousness disturbances and muscular spasm which affects about 1% of the human population. Despite major technological advances done in medicine in the last years there was no sufficient progress towards overcoming it. Application of advanced statistical methods and computer image analysis offers the hope for accurate detection and later removal of an epileptiform focuses which are the cause of some types of epilepsy. The aim of this work was to create a computer system that would help to find and diagnose disorders of blood circulation in the brain This may be helpful for the diagnosis of the epileptic seizures onset in the brain.

Grzegorczyk, Dawid; Dunin-W?sowicz, Dorota; Mulawka, Jan J.

2010-06-01

36

Microchip UV absorbance detection applied to isoelectric focusing of proteins.  

PubMed

Isoelectric focusing (IEF) is considered as an attractive separation technique for biologically amphoteric compounds (e.g., proteins and peptides) based on their isoelectric point (pI). With the advancement in micromachining technology, microchip format IEF has attracted significant attention. Both single-point and whole column imaging detection (WCID) methods have been employed for analyzing the separation performance in a microchip. WCID is more favorable than single-point detection because the latter requires the focused bands to be mobilized and thus adds more complexity to the design and operation of such microchips. Fluorescence- and UV absorbance-based WCID have been successfully adapted in glass and PDMS microchips. We have developed polydimethylsiloxane (PDMS) microchips for IEF applications where UV-WCID is employed for evaluating the separation performance. The chips are designed for use in the iCE280 analyzer (Convergent Bioscience Inc., Toronto), for capillary-based IEF where UV-WCID is employed for analyzing the separation performance. Three kinds of microchips that have been successfully developed using standard soft lithography technology are described in detail. PMID:23329463

Ou, Junjie; Ren, Carolyn L

2013-01-01

37

Complete Inhibition Of Ultrasound Induced Cytolysis In The Presence Of Inertial Cavitation  

NASA Astrophysics Data System (ADS)

The investigation of ultrasound for biotechnological applications including non-invasive surgery (HIFU), drug/gene delivery to cells (sonoporation) or through the skin (sonophoresis) and ultrasound assisted bioreactors has focused mainly on the physical effects of ultrasound. The beneficial effects of ultrasound rely on a number of application-dependent mechanisms, and may include tissue heating, acoustic streaming or cavitation. Although acoustic cavitation is necessary in some systems, cavitation bubbles simultaneously result in uncontrollable cell damage and cytolysis. Thus, the development of a number of biotechnological uses of ultrasound has been hampered by the necessity to constrain exposure parameters in order to prevent the occurrence of acoustic cavitation or to at least limit the detrimental effects of cavitation. The current study shows that non-toxic concentrations of specific n-alkyl solutes completely inhibit ultrasound induced cytolysis of in vitro suspensions of human leukemia cells (HL-60). Protection of the whole cell population from cytolysis is achieved even under extreme ultrasound exposure conditions that result in cytolysis of 100 % of the cell population in the absence of the n-alkyl solutes. Furthermore, the n-alkyl solutes did not hinder the process of inertial cavitation. This method may allow utilization of beneficial effects of ultrasound and cavitation while protecting cells from cavitation induced cytolysis and thereby presents new possibilities for ultrasound in medicine and biology.

Sostaric, Joe Z.; Miyoshi, Norio; Riesz, Peter; de Graff, William G.; Mitchell, James B.

2006-05-01

38

Localization of ultrasound-induced in vivo neurostimulation in the mouse model.  

PubMed

Developments in the use of ultrasound to stimulate and modulate neural activity have raised the possibility of using ultrasound as a new investigative and therapeutic tool in brain research. Although the phenomenon of ultrasound-induced neurostimulation has a long history dating back many decades, until now there has been little evidence of a clearly localized effect in the brain, a necessary requirement for the technique to become genuinely useful. Here we report clearly distinguishable effects in sonicating rostral and caudal regions of the mouse motor cortex. Motor responses measured by normalized electromyography in the neck and tail regions changed significantly when sonicating the two different areas of motor cortex. Response latencies varied significantly according to sonication location, suggesting that different neural circuits are activated depending on the precise focus of the ultrasound beam. Taken together, our findings present good evidence of the ability to target selective parts of the motor cortex with ultrasound neurostimulation in the mouse, an advance that should help to set the stage for developing new applications in larger animal models, including humans. PMID:24642220

King, Randy L; Brown, Julian R; Pauly, Kim Butts

2014-07-01

39

Focus  

NSDL National Science Digital Library

The Institute for Research on Poverty at University of Wisconsin-Madison held a welfare reform conference in March 1997. Both the summary and full proceedings of the conference are available. Note that the summary is available in Focus. The Personal Responsibility and Work Opportunity Reconciliation Act of 1996 was passed on August 22, 1996. The Act "changed the nation's welfare system into one that requires work in exchange for time-limited assistance."

1976-01-01

40

Ultrasound-Induced Blood-Brain Barrier Opening  

PubMed Central

Over 4 million U.S. men and women suffer from Alzheimer's disease; 1 million from Parkinson's disease; 350,000 from multiple sclerosis (MS); and 20,000 from amyotrophic lateral sclerosis (ALS). Worldwide, these four diseases account for more than 20 million patients. In addition, aging greatly increases the risk of neurodegenerative disease. Although great progress has been made in recent years toward understanding of these diseases, few effective treatments and no cures are currently available. This is mainly due to the impermeability of the blood-brain barrier (BBB) that allows only 5% of the 7000 small-molecule drugs available to treat only a tiny fraction of these diseases. On the other hand, safe and localized opening of the BBB has been proven to present a significant challenge. Of the methods used for BBB disruption shown to be effective, Focused Ultrasound (FUS), in conjunction with microbubbles, is the only technique that can induce localized BBB opening noninvasively and regionally. FUS may thus have a huge impact in trans-BBB brain drug delivery. The primary objective in this paper is to elucidate the interactions between ultrasound, microbubbles and the local microenvironment during BBB opening with FUS, which are responsible for inducing the BBB disruption. The mechanism of the BBB opening in vivo is monitored through the MRI and passive cavitation detection (PCD), and the safety of BBB disruption is assessed using H&E histology at distinct pressures, pulse lengths and microbubble diameters. It is hereby shown that the BBB can be disrupted safely and transiently under specific acoustic pressures (under 0.45 MPa) and microbubble (diameter under 8 ?m) conditions.

Konofagou, Elisa E.; Tung, Yao-Sheng; Choi, James; Deffieux, Thomas; Baseri, Babak; Vlachos, Fotios

2014-01-01

41

High Resolution Focusing Analysis and Inversion for Small Scatterer Detection.  

National Technical Information Service (NTIS)

This report, in slightly different format, was submitted to the monitor November, 1994. We have adapted our current inversion algorithm to the length and time scales of the sea mine detection problem. We produced inversion output for numerically generated...

N. Bleistein J. K. Cohen

1996-01-01

42

Electronic detection of focused Cherenkov rings from aerogel  

NASA Astrophysics Data System (ADS)

The recent development of highly transparent aerogel has permitted its use as a Cherenkov radiator in a focused (non-Rayleigh-scattered) mode. We report on the optical properties of this aerogel obtained by observation of Cherenkov rings with single-electron-sensitive phototubes. The dependence on aerogel radiator thickness of the number of Cherenkov ring hit points and background is shown and compared to expectations. A 5 cm thick radiator of this aerogel will permit {?}/{K} identification up to 20 GeV/c.

De Leo, R.; Lagamba, L.; Manzari, V.; Nappi, E.; Scognetti, T.; Alemi, M.; Becker, H.; Forty, R.; Adachi, I.; Suda, R.; Sumiyoshi, T.; Leone, A.; Perrino, R.; Matteuzzi, C.; Seguinot, J.; Ypsilantis, T.; Cisbani, E.; Frullani, S.; Garibaldi, F.; Iodice, M.; Urciuoli, G. M.

1997-02-01

43

Detection of liquid hazardous molecules using linearly focused Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In security, it is an important issue to analyze hazardous materials in sealed bottles. Particularly, prompt nondestructive checking of sealed liquid bottles in a very short time at the checkpoints of crowded malls, stadiums, or airports is of particular importance to prevent probable terrorist attack using liquid explosives. Aiming to design and fabricate a detector for liquid explosives, we have used linearly focused Raman spectroscopy to analyze liquid materials in transparent or semi-transparent bottles without opening their caps. Continuous lasers with 532 nm wavelength and 58 mW/130 mW beam energy have been used for the Raman spectroscopy. Various hazardous materials including flammable liquids and explosive materials have successfully been distinguished and identified within a couple of seconds. We believe that our technique will be one of suitable methods for fast screening of liquid materials in sealed bottles.

Cho, Soo Gyeong; Chung, Jin Hyuk

2013-05-01

44

Theoretical Studies on Ultrasound Induced Hall Voltage and Its Application in Hall Effect Imaging  

NASA Astrophysics Data System (ADS)

Based on the principles of the Hall effect for ultrasound excitation and wave propagation in a static magnetic field, the theory of ultrasound induced Hall voltage generation is derived in explicit formulae with consideration of the acoustic radiation for a planar transducer. It is proved by numerical simulations that the induced Hall voltage is mainly generated at the conductivity boundary and can be used to map the spatial variation of the conductivity value along the acoustic transmission path. Both the simulated Hall voltage and the reconstructed image show good agreement with the experimental results of Wen [Ultrasonic Imaging 20 (1998) 206, 21 (1999) 186]. The promising simulation results suggest the potential of implementing medical electrical impedance imaging by means of ultrasound induced Hall effect imaging.

Chen, Xuan-Ze; Ma, Qing-Yu; Zhang, Feng; Sun, Xiao-Dong; Cui, Hao-Chuan

2012-09-01

45

7C-6 Motion Artifact Reduction by ECG Gating in Ultrasound Induced Thermal Strain Imaging  

Microsoft Academic Search

Cardiac motion related artifact in ultrasound induced thermal strain imaging (TSI) was reduced in-vitro and in-vivo using ECG gating. Tissue motion due to the heart beat is a major challenge for in-vivo TSI application, especially for cardiovascular systems. Temporal variation of the relative position between the transducer and the artery will induce decorrelation in speckle tracking. Tissue deformation produces mechanical

K. Kim; S.-W. Huang; R. Olafsson; C. Jia; R. S. Witte; M. O'Donnell

2007-01-01

46

Ultrasonic Sensitivity of Strain-Insensitive Fiber Bragg Grating Sensors and Evaluation of Ultrasound-Induced Strain  

PubMed Central

In conventional ultrasound detection in structures, a fiber Bragg grating (FBG) is glued on or embedded in the structure. However, application of strain to the structure can influence the sensitivity of the FBG toward ultrasound and can prevent its effective detection. An FBG can work as a strain-insensitive ultrasound sensor when it is not directly glued to the monitored structure, but is instead applied to a small thin plate to form a mobile sensor. Another possible configuration is to affix an FBG-inscribed optical fiber without the grating section attached to the monitored structure. In the present study, sensitivity to ultrasound propagated through an aluminum plate was compared for a strain-insensitive FBG sensor and an FBG sensor installed in a conventional manner. Strains induced by ultrasound from a piezoelectric transducer and by quasi-acoustic emission of a pencil lead break were also quantitatively evaluated from the response amplitude of the FBG sensor. Experimental results showed that the reduction in the signal-to-noise ratio for ultrasound detection with strain-insensitive FBG sensors, relative to traditionally-installed FBG sensors, was only 6 dB, and the ultrasound-induced strain varied within a range of sub-micron strains.

Tsuda, Hiroshi; Kumakura, Kenji; Ogihara, Shinji

2010-01-01

47

Ultrasound-induced contraction of the carotid artery in vitro.  

PubMed

Ultrasound is known to produce a range of nonlethal responses in cells and tissues. Frequencies in the kilohertz ultrasound range have been shown to produce relaxation in large arteries. The present work explores the effects of insonation at MHz frequencies, representative of those used diagnostically and therapeutically, in an in vitro preparation of the carotid artery. Fresh 12.7 mm wide rings of equine common carotid artery obtained from the abattoir were mounted in a purpose-made myograph. They were immersed in a bath of Krebs-Ringer buffer at 37 degrees C and were positioned at the focus of an ultrasound beam from a weakly focused 3.2 MHz source. Continuous wave insonation produced contraction. The tension increased rapidly over the first 2 min, followed by a slower increase for the duration of the exposure up to 15 min. At a power of 145 mW a maximum contractile stress of 0.04 +/- 0.03 mN/mm(2) (mean +/- SD, n = 77) was measured, which was approximately 4% of the maximum wall stress generated by noradrenaline (0.1 mM). The magnitude of the response was weakly dependent on power in the range 72-145 mW and was not significantly different for pulsed and continuous wave stimulation where time averaged power was constant. The response was unaffected by mechanical removal of the endothelium. The ultrasound beam generated insufficient radiation force to produce a measurable effect and streaming at the vessel surface was very small compared with flow rates known to produce physiologic effects. The temperature rise at the beam focus was approximately 0.3 degrees C and we hypothesise that this contributes to the observed response, probably through changes in ion channel activity in smooth muscle cell membranes. (E-mail: e.martin@exeter.ac.uk). PMID:19900746

Martin, Eleanor M; Duck, Francis A; Ellis, Richard E; Winlove, C Peter

2010-01-01

48

Ultrasound-induced cellular uptake of plasmonic gold nanorods  

NASA Astrophysics Data System (ADS)

Delivery of contrast agents and their interaction with cells is emerging as an important tool in cancer imaging and therapy. An alternative to traditional molecular targeting schemes that induce endocytotic uptake of contrast agents in cells is presented here. Specifically, the application of high-intensity, focused ultrasound (HIFU) was used to enhance uptake of gold nanorods in pancreatic cancer cells in vitro. A significant increase was observed in gold nanorod uptake when cells were incubated with nanorods and treated with HIFU. Additionally, inclusion of liquid-filled, perfluorocarbon (PFC) microdroplets in cell samples incubated with nanorods and treated with HIFU exhibited greater uptake of gold over those samples exposed to HIFU without microdroplets. Furthermore, the level of acoustic pressure required to increase nanoparticle uptake did not significantly decrease cell viability. Therefore, improved intracellular delivery of nanoparticle contrast agents is possible using HIFU without compromising cell viability. Since nanoparticle delivery is mechanically induced, this method can apply to a broad range of cancer imaging and therapy applications.

Hannah, Alexander; Wilson, Katheryne; Homan, Kimberly; Emelianov, Stanislav

2011-02-01

49

Detection of explosives by Terahertz synthetic aperture imaging—focusing and spectral classification  

Microsoft Academic Search

In the adaptation of Terahertz (THz) synthetic aperture imaging to stand-off screening of concealed weapons and explosives, the incoming THz wavefronts exhibit significant curvature that must be considered in the image reconstruction. Consequently, the imaging array must be focused at a specific distance to correct for the wavefront curvature. In addition to the focusing correction, detection of explosives requires spectral

Alexander Sinyukov; Ivan Zorych; Zoi-Heleni Michalopoulou; Dale Gary; Robert Barat; John F. Federici

2008-01-01

50

A Detection Theoretic Approach to Digital Fingerprinting With Focused Receivers Under Uniform Linear Averaging Gaussian Attacks  

Microsoft Academic Search

We consider the digital fingerprinting problem where colluders apply uniform linear averaging followed by AWGN. For each user, the receiver computes the correlation between the attacked signal and that user's fingerprint, and performs thresholding (focused detection). We model the finger- printing problem as a multi-user communications problem and develop a detection theoretic framework. Assuming independent colluders, we derive generic exact

Ozgur Dalkilic; Ersen Ekrem; Suphi Eray Varlik; Mehmet Kivanç Mihçak

2010-01-01

51

Low-intensity ultrasound-induced cellular destruction and autophagy of nasopharyngeal carcinoma cells  

PubMed Central

Ultrasound therapy, as a non-invasive modality, has been attracting extensive attention in the management of malignant tumors. The present study aimed to investigate low-intensity ultrasound-induced cellular destruction and autophagy in nasopharyngeal carcinoma cells in vitro. Nasopharyngeal carcinoma CNE2 cells were subjected to ultrasound exposure, as tumor model cells, at an intensity of 1.35 W/cm2. Cytotoxicity was investigated 24 h after ultrasound treatment. Nuclear damage was observed using nuclear staining with Hoechst 33258. Mitochondrial dysfunction was measured using confocal laser scanning microscopy with rhodamine123 staining. Mitochondrial morphology and autophagy were observed using transmission electron microscopy (TEM). Low-intensity ultrasound significantly killed CNE2 cells proportional to the ultrasonic treatment time. Upon nuclear staining, nuclear condensation and typical apoptotic bodies were noted in the CNE2 cells exposed to ultrasound wave for 12 sec. A collapse in mitochondrial membrane potential was noted in the treated cells. Upon TEM, swollen mitochondria, more vacuoles and autophagy were noted after ultrasound treatment. Our findings demonstrate that low-intensity ultrasound significantly damages CNE2 cells and emphasize that autophagy may be an important event in ultrasound-induced cell death.

WANG, PING; LEUNG, ALBERT WINGNANG; XU, CHUANSHAN

2011-01-01

52

Comparison of isoelectric focusing and polymerase chain reaction for the detection of ?-lactamases.  

PubMed

Extended spectrum ?-lactamases (ESBLs) have been observed in virtually all the species of family Enterobacteriaceae. Threat posed by antibiotic resistance because of ESBLs is more serious as a number of technical problems are associated with the detection of these enzymes. Although a number of detection methods have been designed for ESBLs, every method has its own benefits and shortcomings as well. In earlier days, isoelectric focusing (IEF) was used as the gold standard for ESBL detection. This study was undertaken to compare IEF with polymerase chain reaction, a method which has been extensively used for ESBL detection these days. PMID:20966574

Sharma, J; Ray, P; Sharma, M; Ghosh, S

2010-01-01

53

Mechanism of the protective effects of long chain n-alkyl glucopyranosides against ultrasound-induced cytolysis of HL-60 cells  

PubMed Central

Recently it has been shown that long chain (C5 to C8) n-alkyl glucopyranosides completely inhibit ultrasound-induced cytolysis [1]. This protective effect has possible applications in HIFU (high intensity focused ultrasound) for tumor treatment, and in ultrasound assisted drug delivery and gene therapy. n-Alkyl glucopyranosides with hexyl (5mM), heptyl (3mM), octyl (2mM) n-alkyl chains protected 100% of HL-60 cells in-vitro from 1.057 MHz ultrasound induced cytolysis under a range of conditions that resulted in 35% to 100% cytolysis in the absence of glucopyranosides. However the hydrophilic methyl-?-D-glucopyranoside did not protect cells. The surface active n-alkyl glucopyranosides accumulate at the gas-liquid interface of cavitation bubbles. The OH radicals and H atoms formed in collapsing cavitation bubbles react by H-atom abstraction from either the n-alkyl chain or the glucose moiety of the n-alkyl glucopyranosides. Owing to the high concentration of the long chain surfactants at the gas-liquid interface of cavitation bubbles, the initially formed carbon radicals on the alkyl chains are transferred to the glucose moieties to yield radicals which react with oxygen leading to the formation of hydrogen peroxide. In this work we find that the sonochemically produced hydrogen peroxide yields from oxygen-saturated solutions of long chain (hexyl, octyl) n-alkyl glucopyranosides at 614 kHz and 1.057 MHz ultrasound increase with increasing n-alkyl glucopyranoside concentration but are independent of concentration for methyl-?-D-glucopyranoside. These results are consistent with the previously proposed mechanism of sonoprotection [1]. This sequence of events prevents sonodynamic cell killing by initiation of lipid peroxidation chain reactions in cellular membranes by peroxyl and/or alkoxyl radicals [2].

Cheng, Jason Y.; Riesz, Peter

2007-01-01

54

Controlled trial of serum isoelectric focusing in the detection of the cystic fibrosis gene  

Microsoft Academic Search

Three independent observers assessed the discriminating power of serum isoelectric focusing in detecting the presence of the cystic fibrosis gene. On the basis of average scores, four out of 23 cystic fibrosis patients, six out of 22 heterozygotes, and three out of 16 controls were misclassified. However, the mean scores for the cystic fibrosis and heterozygote groups were significantly different

David J. H. Brock; Caroline Hayward; Maurice Super

1982-01-01

55

A Distance Measure for Attention Focusing and Anomaly Detection in Systems Monitoring  

NASA Technical Reports Server (NTRS)

Any attempt to introduce automation into the monitoring of complex physical systems must start from a robust anomaly detection capability. This task is far from straightforward, for a single definition of what constitutes an anomaly is difficult to come by. In addition, to make the monitoring process efficient, and to avoid the potential for information overload on human operators, attention focusing must also be addressed. When an anomaly occurs, more often than not several sensors are affected, and the partially redundant information they provide can be confusing, particularly in a crisis situation where a response is needed quickly. Previous results on extending traditional anomaly detection techniques are summarized. The focus of this paper is a new technique for attention focusing.

Doyle, R.

1994-01-01

56

Effect of gravitational focusing on annual modulation in dark-matter direct-detection experiments.  

PubMed

The scattering rate in dark-matter direct-detection experiments should modulate annually due to Earth's orbit around the Sun. The rate is typically thought to be extremized around June 1, when the relative velocity of Earth with respect to the dark-matter wind is maximal. We point out that gravitational focusing can alter this modulation phase. Unbound dark-matter particles are focused by the Sun's gravitational potential, affecting their phase-space density in the lab frame. Gravitational focusing can result in a significant overall shift in the annual-modulation phase, which is most relevant for dark matter with low scattering speeds. The induced phase shift for light O(10)??GeV dark matter may also be significant, depending on the threshold energy of the experiment. PMID:24483881

Lee, Samuel K; Lisanti, Mariangela; Peter, Annika H G; Safdi, Benjamin R

2014-01-10

57

Diffraction analysis and evaluation of several focus- and track-error detection schemes for magneto-optical disk systems  

NASA Technical Reports Server (NTRS)

A commonly used tracking method on pre-grooved magneto-optical (MO) media is the push-pull technique, and the astigmatic method is a popular focus-error detection approach. These two methods are analyzed using DIFFRACT, a general-purpose scalar diffraction modeling program, to observe the effects on the error signals due to focusing lens misalignment, Seidel aberrations, and optical crosstalk (feedthrough) between the focusing and tracking servos. Using the results of the astigmatic/push-pull system as a basis for comparison, a novel focus/track-error detection technique that utilizes a ring toric lens is evaluated as well as the obscuration method (focus error detection only).

Bernacki, Bruce E.; Mansuripur, M.

1992-01-01

58

Isoelectric focusing and ELISA for detecting adulteration of donkey milk with cow milk.  

PubMed

Donkey milk has been recently revalued intensely due to its nutritional properties. Moreover, donkey milk has been proposed as an effective alternative food for some infants with cow milk allergy. Two fast analytical methods were proposed to detect the fraudulent practice of blending cow milk to donkey milk. Detection of cow ?s1-casein bands along the profiles of experimental donkey-cow milk mixtures analyzed by isoelectric focusing was adequate to estimate cow milk used as adulterant of donkey milk starting from 5% (v/v). An ELISA-based method using the antipeptide antibodies raised against the 1-28 sequence stretch of cow ?-casein was also developed for an accurate definition of composition of donkey-cow milk mixtures. The presence of cow milk at levels as low as 0.5% (v/v) was detected in donkey-cow milk mixtures prepared at laboratory scale and assayed by ELISA. PMID:24892189

Pizzano, Rosa; Salimei, Elisabetta

2014-06-25

59

Ultrasound-induced cell lysis and sonoporation enhanced by contrast agents.  

PubMed

The enhancement of ultrasound-induced cell destruction, lysis, and sonoporation in low cell concentration suspensions (2 x 10(5)/mL) by the presence of contrast agents (gas bubble to cell ratio = 230) was demonstrated using cervical cancer cells (HeLa S3) suspensions containing micron-size denatured albumin microspheres filled with air (Albunex) or octafluoropropane (Optison). The suspensions were insonificated by 2-MHz continuous or tone burst ultrasound in near field. The spatial peak-pressure amplitude was 0.2 MPa. The enhancement of cell destruction due to Optison was shown to be much higher than that due to Albunex for similar bubble concentration and ultrasound conditions. For tone burst exposures, significant lysis and sonoporation only occurred in the presence of a contrast agent. The majority of the bioeffects observed occurred in the first 5 min of exposure. The relationship between the enhancement of bioeffects and duty cycle of tone burst ultrasound appears to indicate that both stable gas spheres of contrast agents and cavitation nuclei created by the disruption of the gas spheres play a significant role in causing the bioeffects. PMID:10335644

Ward, M; Wu, J; Chiu, J F

1999-05-01

60

Detection of Cracks at Welds in Steel Tubing Using Flux Focusing Electromagnetic Probe  

NASA Technical Reports Server (NTRS)

The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected by simply snaking an eddy current coil into the intake tube of the vessel. The drawback of the eddy current method has been the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at weldments [1]. The flaw detection mechanism of the flux focusing electromagnetic probe can help alleviate these difficulties and provide a unique capability for detecting longitudinal fatigue cracks in critical tube structures. The Flux Focusing Electromagnetic Flaw Detector, originally invented for the detection of fatigue and corrosion damage in aluminum plates [2-3], has been adapted for use in testing steel tubing for longitudinal fatigue cracks. The modified design allows for the probe to be placed axisymmetrically into the tubing, inducing eddy currents in the tube wall. The pickup coil of the probe is fixed slightly below the primary windings and is rotated 90 so that its axis is normal to the tube wall. The magnetic flux of the primary coil is focused through the use of ferromagnetic material so that in the absence of fatigue damage there will be no flux linkage with the pickup coil. The presence of a longitudinal fatigue crack will cause the eddy currents induced in the tube wall to flow around the flaw and directly under the pickup coil. The magnetic field associated with these currents will then link the pickup coil and an unambiguous increase in the output voltage of the probe will be measured. The use of the flux focusing electromagnetic probe is especially suited for the detection of flaws originating at or near tube welds. The probe is shown to discriminate against signals due solely to the weld joint so that flaw signals are not hidden in the background in these locations. Experimental and finite element modeling results are presented for the flaw detection capabilities of the probe in stainless steel tubes.

Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min

1994-01-01

61

Isoelectric focusing in agarose gel for detection of oligoclonal bands in cerebrospinal and other biological fluids.  

PubMed

Isoelectric focusing (IEF) coupled with immunodetection (immunofixation or immunoblotting) has become the leading technique for the detection and study of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) and also is increasingly used in other body fluids such as the tear and serum. Limited commercial availability of precast agarose IEF gels for research and a need for customization prompted reporting a detailed general protocol for the preparation and casting of agarose IEF gel along with sample, control, and isoelectric point marker preparation and carrying out the focusing itself for CSF OCBs. However, the method is readily adaptable to the use of other body fluid specimens and, possibly, research specimens such as culture fluids as well. PMID:22585491

Csako, Gyorgy

2012-01-01

62

Magnetic focusing immunosensor for the detection of Salmonella typhimurium in foods  

NASA Astrophysics Data System (ADS)

From 1988 through 1992 Salmonellosis accounted for 27% of the total reported foodborne disease outbreaks and 57% of the outbreaks in which the pathogen was identified. The prevalence of Salmonellosis and the new requirements to monitor the organism as a marker in pathogen reduction programs will drive the need for rapid, on-site testing. A compact fiber optic fluorometer using a red diode laser as an excitation source and fiber probes for analyte detection has been constructed and used to measure Salmonella. The organisms were isolated with anti-Salmonella magnetic beads and were labeled with a secondary antibody conjugated to a red fluorescent dye. The response of the system was proportional to the concentration of Salmonella typhimurium from 3.2 X 105 colony forming units (CFU)/ml to 1.6 X 107 CFU/ml. The system was developed to utilize a fiber-optic magnetic focusing problem that attracted the magnetic microspheres to the surface of a sample chamber directly in front of the excitation and emission fibers. The signal obtained from a homogenous suspension of fluorescent magnetic microspheres was 9 to 10 picowatts. After focusing, the signal from the fluorescent labeled magnetic microspheres increased to 200 picowatts, approximately 20 times greater than the homogeneous suspension. The magnetic focusing assay detected 1.59 X 105 colony forming units/ml of Salmonella typhimurium cultured in growth media. The process of magnetic focusing in front of the fibers has the potential to reduce the background fluorescence from unbound secondary antibodies, eliminating several rinsing steps, resulting in a simple rapid assay.

Pivarnik, Philip E.; Cao, He; Letcher, Stephen V.; Pierson, Arthur H.; Rand, Arthur G.

1999-01-01

63

Oligoclonal bands in cerebrospinal fluid detected by PhastSystem isoelectric focusing.  

PubMed

Pharmacia's "PhastSystem" for semi-automated isoelectric focusing (IEF) in thin precast polyacrylamide gels (PAGE) was found to be as sensitive as high-resolution protein electrophoresis (HRPE) in agarose gels and conventional PAGE-IEF for detection of oligoclonal banding (OB) in concentrated cerebrospinal fluid (CSF) samples. Both PhastSystem IEF and HRPE revealed OB in CSF from eight of nine multiple sclerosis patients and four of 10 patients with various types of infection of the central nervous system as opposed to only two of 70 patients with miscellaneous neuropsychiatric disorders. The PhastSystem also frequently detected OB in silver-stained, unconcentrated CSF from patients with multiple sclerosis. PMID:1688744

Wybo, I; Van Blerk, M; Malfait, R; Goubert, P; Gorus, F

1990-01-01

64

Capillary isoelectric focusing of proteins and microorganisms in dynamically modified fused silica with UV detection.  

PubMed

We suggest a method for the reproducible and efficient capillary isoelectric focusing of proteins and microorganisms in the pH gradient 3-10. The method involves the segmental injection of the simple ampholytes, the solution of the selected electrolytes, and the sample mixture of bioanalytes and carrier ampholytes to the fused silica capillaries dynamically modified by poly(ethylene glycol), PEG 4000, which is added to the catholyte, the anolyte and injected solutions. In order to receive the reproducible results, the capillaries were rinsed by the mixture of acetone/ethanol between analyses. For the tracing of the pH gradients the low-molecular-mass pI markers were used. The simple proteins and the mixed cultures of microorganisms, Saccharomyces cerevisiae CCM 8191, Escherichia coli CCM 3954, Candida albicans CCM 8180, Candida parapsilosis, Candida krusei, Staphylococcus aureus, Streptococcus agalactiae CCM 6187, Enterococcus faecalis CCM 4224, Staphylococcus epidermidis CCM 4418 and Stenotrophomonas maltophilia, were focused and separated by the method suggested. The minimum detectable number of microbial cells was 5x10(2) to 1x10(3) with on-column UV detection at 280 nm. PMID:16765111

Horká, Marie; R?zicka, Filip; Horký, Jaroslav; Holá, Veronika; Slais, Karel

2006-09-01

65

Optical Generation and Detection of High-Frequency Focused Ultrasound and Associated Nonlinear Effects  

NASA Astrophysics Data System (ADS)

In this thesis, optical generation and detection of high-frequency ultrasound are presented. On the generation side, high-efficiency optical transmitters have been devised and developed which can generate high-frequency and high-amplitude pressure. Conventional optoacoustic transmitters have suffered from poor optoacoustic energy conversion efficiency (10-7˜10-8). Therefore, pressure amplitudes were usually weak for long-range imaging (several cm) and too weak to induce any therapeutic effects. Here, far beyond such traditional regime, therapeutic pressure amplitudes of tens of MPa were achieved optoacoustically. First, high-efficiency optoacoustic sources were developed in planar geometries by using carbon nanotubepolymer composites. The planar transmitters could generate 18-fold stronger pressure than thin metallic films used as references, together with providing broadband and high-frequency spectra over 120 MHz. Then, the thin-film transmitters were formed on concave substrates to generate and simultaneously focus the ultrasound. Unprecedented optoacoustic pressure was achieved at lens focus: >50 MPa in positive and >20 MPa in negative peaks. These amplitudes were sufficient to induce strong shock waves and acoustic cavitation. Due to the high-frequency operation, such therapeutic pressure and the induced effects were tightly localized onto focal widths of 75microm in lateral and 400 microm in axial directions, which are an order of magnitude smaller than those of traditional piezoelectric transducers. The shock waves and the cavitation effects were investigated in various ways. High focal gains and short distances for shock formation were suggested as main features. The optoacoustic approach is expected to open numerous opportunities for a broad range of biomedical applications demanding high-accuracy treatment with minimal damage volumes around focal zones. For optical detection of ultrasound, optical microring resonators have been used due to their broadband frequency responses (˜100 MHz) and high sensitivity. However, their spatial responses due to the particular ring shape have not been investigated especially for high-frequency ranges. Here, the microring responses were characterized in this regime. As a final subject, the microrings were used to detect focused ultrasound and realize novel optoacoustic 4f imaging systems which have capabilities of fast 3-D imaging without requiring mathematical reconstruction steps. High-resolution performances were demonstrated by resolving polymer microspheres of 100-microm diameter.

Baac, Hyoung Won

66

Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection  

NASA Astrophysics Data System (ADS)

We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si3N4 and W/Si3N4 to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations.

Patterson, N.; Adams, D. P.; Hodges, V. C.; Vasile, M. J.; Michael, J. R.; Kotula, P. G.

2008-06-01

67

Detecting electrical and hydraulic heterogeneities using seismic focusing and seismoelectric conversions  

NASA Astrophysics Data System (ADS)

When a seismic wave propagates through a porous material and encounters a discontinuity in hydraulic or electrical properties, part of its energy is converted into an electromagnetic signal. Recording and interpreting this signal can be used to infer properties of the subsurface such as electrical conductivity, porosity, permeability, and saturation. However, a major issue of this method is that the amplitude of the converted electromagnetic signal is usually quite low and difficult to measure directly in the field. Sava & Revil recently proposed a seismic focusing technique (which will be referred to as "beamforming"), where multiple seismic sources located around the area of interest (usually placed in boreholes) are used to concentrate seismic energy at a desired location and time. If the focus point is located at a heterogeneity, a seismoelectric conversion will take place with a much greater amplitude than if a unique source had been used, making the converted signal easier to detect. So far, this new technique has only been tested on a simple case study and further investigations are needed to assess its strengths, weaknesses, and future potential applications. In this thesis, I develop a finite-element numerical model for the beamforming technique (coupled with seismoelectric conversions) in the frequency domain. I then perform a set of important numerical tests to assess the properties of the converted electromagnetic signals generated by the beamforming technique. Finally, the numerical beamforming model is successfully applied to track the location of a water saturation front inside an oil reservoir undergoing a water flooding process.

Barnier, Guillaume

68

Femtomolar concentration detection limit and zeptomole mass detection limit for protein separation by capillary isoelectric focusing and laser-induced fluorescence detection.  

PubMed

Fluorescence tends to produce the lowest detection limits for most forms of capillary electrophoresis. Two issues have discouraged its use in capillary isoelectric focusing. The first issue is fluorescent labeling of proteins. Most labeling reagents react with lysine residues and convert the cationic residue to a neutral or anionic product. At best, these reagents perturb the isoelectric point of the protein. At worse, they convert each protein into hundreds of different fluorescent products that confound analysis. The second issue is the large background signal generated by impurities within commercial ampholytes. This background signal is particularly strong when excited in the blue portion of the spectrum, which is required by many common fluorescent labeling reagents. This paper addresses these issues. For labeling, we employ Chromeo P540, which is a fluorogenic reagent that converts cationic lysine residues to cationic fluorescent products. The reaction products are excited in the green, which reduces the background signal generated by impurities present within the ampholytes. To further reduce the background signal, we photobleach ampholytes with high-power photodiodes. Photobleaching reduced the noise in the ampholyte blank by an order of magnitude. Isoelectric focusing performed with photobleached pH 3-10 ampholytes produced concentration detection limits of 270 +/- 25 fM and mass detection limits of 150 +/- 15 zmol for Chromeo P540 labeled beta-lactoglobulin. Concentration detection limits were 520 +/- 40 fM and mass detection limits were 310 +/- 30 zmol with pH 4-8 ampholytes. A homogenate was prepared from a Barrett's esophagus cell line and separated by capillary isoelectric focusing, reproducibly generating dozens of peaks. The sample taken for the separation was equal to the labeled protein homogenate from three cells. PMID:19206532

Ramsay, Lauren M; Dickerson, Jane A; Dada, Oluwatosin; Dovichi, Norman J

2009-03-01

69

Femtomolar Concentration Detection Limit and Zeptomole Mass Detection Limit for Protein Separation by Capillary Isoelectric Focusing and Laser-induced Fluorescence Detection  

PubMed Central

Fluorescence tends to produce the lowest detection limits for most forms of capillary electrophoresis. Two issues have discouraged its use in capillary isoelectric focusing. The first issue is fluorescent labeling of proteins. Most labeling reagents react with lysine residues and convert the cationic residue to a neutral or anionic product. At best, these reagents perturb the isoelectric point of the protein. At worse, they convert each protein into hundreds of different fluorescent products that confound analysis. The second issue is the large background signal generated by impurities within commercial ampholytes. This background signal is particularly strong when excited in the blue portion of the spectrum, which is required by many common fluorescent labeling reagents. This paper addresses these issues. For labeling, we employ Chromeo P540, which is a fluorogenic reagent that converts cationic lysine residues to cationic fluorescent products. The reaction products are excited in the green, which reduces the background signal generated by impurities present within the ampholytes. To further reduce the background signal, we photobleach ampholytes with high-power photodiodes. Photobleaching reduced the noise in the ampholyte blank by an order of magnitude. Isoelectric focusing performed with photobleached pH 3–10 ampholytes produced concentration detection limits of 270 ± 25 fM and mass detection limits of 150 ± 15 zmol for Chromeo P540 labeled ?-lactoglobulin. Concentration detection limits were 520 ± 40 fM and mass detection limits were 310 ± 30 zmol with pH 4–8 ampholytes. A homogenate was prepared from a Barrett’s esophagus cell line and separated by capillary isoelectric focusing, reproducibly generating dozens of peaks. The sample taken for the separation was equal to the labeled protein homogenate from three cells.

Ramsay, Lauren M.; Dickerson, Jane A.; Dada, Oluwatosin; Dovichi, Norman J.

2009-01-01

70

High-efficiency molecular counting in solution: Single-molecule detection in electrodynamically focused microdroplet streams  

SciTech Connect

We report fluorescence detection of individual rhodamine 6G molecules using a linear quadrupole to focus streams of microdroplets through the waist of a counterpropagating cw Ar{sup +} laser. Since the terminal velocity scales as the square of the droplet diameter, the droplet-laser interaction time was `tunable` between 5 and 200 ms by using water samples spiked with a small, variable (2-5% v/v) amount of glycerol. Fluorescence bursts from droplets containing single molecules were clearly distinguished from the blanks in real time with an average signal-to-noise ratio of about 10, limited primarily by photobleaching and droplet size fluctuations (<1%). The volume throughput rates associated with this approach (approx. 10 pL/s) are roughly 10{sup 3} higher than those associated with particle levitation techniques, with minimal sacrifice in sensitivity. Total molecular detection efficiencies of about 80% (at >99% confidence) were obtained for 100 and 15 fM rhodamine 6G solutions, in good agreement with detailed theoretical calculations and statistical limitations. 39 refs., 7 figs., 1 tab.

Lermer, N.; Barnes, M.D.; Kung, C.Y.; Whitten, W.B.; Ramsey, J.M. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States)

1997-06-01

71

SEIS/INSIGHT and Mars seismology: Development status and focus on the Impact detection  

NASA Astrophysics Data System (ADS)

The INSIGHT NASA Discovery mission will deploy in September 2016 a 3 axis Very Broad band seismometer and a 3 axis SP seismometer, as well as other instruments enabling the installation of a complete geophysical observatory recording seismic, heat flow, magnetic and geodetic signals, in addition to atmospheric wind, pressure and temperature. We first present the science goals status of the SEIS experiment and its development status. The SEIS sensor assembly, which contains both the VBB and SP seismometer, will be deployed on the Martian ground by a robotic arm from a Phoenix-type lander platform and protected by a wind and thermal shield. The wind and thermal shield, a vacuum sphere for VBBs and a passive compensation system will achieve a very high protection of the seismometers against temperature and pressure variations, allowing the sensor to operate in the rough Martian thermal environment while reaching a detection threshold below 10^(-9) m/s/s Hz^(-1/2) in the VBB bandwidth and 10^(-8) m/s/s Hz^(-1/2) for the SP. A levelling system will allow the VBB to operate, while providing to both seismometer the best possible mechanical coupling with the ground motion. The SEIS instrument will be provided by CNES, which will coordinate a wide set of international contributors from the Institut de Physique du Globe de Paris, the Imperial College from London and the Open University, the Max-Planck Insitute of Lindau, the École polytechnique fédérale de Zurich (ETHZ), the Jet Propulsion Laboratory and the Institut de l'Aéronautique et de l'Espace from Toulouse. We then illustrate the science goals by a focus on the capability of INSIGHT to detect either seismic or acoustic signals from impacts, with both the seismometers and the pressure sensor, and present both amplitude and occurrence expectation, based on comparative modeling between Mars, Earth and the Moon.

Lognonne, Philippe; Banerdt, William; Pike, Tom; Giardini, Domenico; Christensen, Ulli; Banfield, Don; Mimoun, David; Laudet, Philippe; de Raucourt, Sebastien; Bierwirth, Marco; Zweifel, Peter; Calcutt, Simon; Hurst, Ken; Bruce, Carl

2014-05-01

72

Capillary isoelectric focusing and fluorometric detection of proteins and microorganisms dynamically modified by poly(ethylene glycol) pyrenebutanoate.  

PubMed

The nonionogenic pyrene-based tenside, poly(ethylene glycol) pyrenebutanoate, was prepared and applied in capillary isoelectric focusing with fluorometric detection. This dye was used here as a buffer additive in capillary isoelectric focusing for a dynamic modification of the sample of proteins and microorganisms. The values of the isoelectric points of the labeled bioanalytes were calculated with use of the fluorescent pI markers and were found comparable with pI of the native compounds. The mixed cultures of proteins and microorganisms, Escherichia coli CCM 3954, Staphylococcus epidermidis CCM 4418, Proteus vulgaris, Enterococcus faecalis CCM 4224, and Stenotrophomonas maltophilia, the strains of the yeast cells, Candida albicans CCM 8180, Candida krusei, Candida parapsilosis, Candida glabrata, Candida tropicalis, and Saccharomyces cerevisiae were reproducibly focused and separated by the suggested technique. Using UV excitation for the on-column fluorometric detection, the minimum detectable amount was down to 10 cells injected on the separation capillary. PMID:17165837

Horka, Marie; Ruzicka, Filip; Horký, Jaroslav; Holá, Veronika; Slais, Karel

2006-12-15

73

The role of heating, cavitation and acoustic streaming in mediating ultrasound-induced changes of TGF-beta gene expression in bone cells  

NASA Astrophysics Data System (ADS)

This paper relates ultrasound-induced changes in bone cell function to quantitative data assessing the level of several interaction mechanisms within the exposure environment. Characterisation of ultrasound fields in terms of resultant levels of heating, cavitation and acoustic streaming may provide a novel means of accurately assessing the likelihood of biological effects in vitro.

Harle, J.; Mayia, F.

2004-01-01

74

Digital holographic microscope with automatic focus tracking by detecting sample displacement in real time.  

PubMed

We propose a new method for focus tracking during the recording of a sequence of digital holograms while the sample experiences axial displacement. Corrected reconstruction distances can be automatically calculated, and well-focused amplitude and phase-contrast images can be obtained for each digitized hologram. The method is demonstrated for inspection of microelectromechanical systems subjected to thermal load. The method can be applied as a quasi-real-time procedure. PMID:12885039

Ferraro, Pietro; Coppola, Giuseppe; De Nicola, Sergio; Finizio, Andrea; Pierattini, Giovanni

2003-07-15

75

Focus detection in digital holography by cross-sectional images of propagating waves  

NASA Astrophysics Data System (ADS)

In digital holography, computing a focused image of an object requires a prior knowledge of the distance of the object from the camera. When this distance is not known, it is necessary to repeat the image reconstruction at a range of distances followed by evaluation of each image with a sharpness metric to determine the in-focus distance of the object. Here, we present a method to nd the focus distance by processing the image transverse to the object plane instead of the processing in the image plane as it is usually done. Since the reconstructed hologram image is spatially symmetric around the focus point along the propagation axis, simply nding the symmetry points in the image cross-section speci es the focus location, and no other sharpness metrics are necessary to use. Also with this method, it is possible to nd the focus distances of multiple objects simultaneously, including the phase only objects without any staining. We will present the simulations and the experimental results obtained by a digital holographic microscope.

Özcan, Meriç

2014-02-01

76

Sol-gel column technology for capillary isoelectric focusing of microorganisms and biopolymers with UV or fluorometric detection.  

PubMed

The sol-gel surface modification is used for capillary isoelectric focusing of microorganisms and biopolymers. The coating strongly decreases the electroosmotic flow so that it enables the use of the short capillaries down to 100 mm in the separation length. The examples of capillary isoelectric focusing of the low-molecular-mass pI markers and mixed cultures of microbial populations of Escherichia coli, Candida albicans, Staphylococcus epidermidis, and Enteroccocus faecalis with UV detection are shown. It is possible to quantify bacterial cells according to their peak areas; the minimum detectable number of microbial cells was 5 x 10(2)-1 x 10(3). The compatibility of sol-gel capillaries with sensitive fluorometric detection of fluorescent pI markers together with fluorescein labeled proteins is demonstrated. PMID:12731023

Horká, Marie; Planeta, Josef; R?zicka, Filip; Slais, Karel

2003-05-01

77

A rapid method for separation and detection of human salivary amylase isoenzymes by isoelectric focusing in polyacrylamide gel.  

PubMed

Human salivary proteins were separated by isoelectric focusing on polyacrylamide gel in flat beds at 1000 V for 40 min. Amylase activity was detected after immersing the gel in 0.4 M tris-HCI buffer pH 7.4 to equilibrate the pH gradient. The enzyme activity was detected after diffusion into an overlayer of agarose gel containing an insoluble dye-starch polymer (Phadebas). Both whole human saliva and parotid saliva from 15 different persons contained four amylase components, except in three cases where only three bands were detected. The bands were all focused within a rather narrow pH range (pH 5.4-7.2) and the results were very reproducible. PMID:1065950

Wadström, T; Nord, C E; Kjellgren, M

1976-07-01

78

A Distance Measure for Attention Focusing and Anaomaly Detection in Systems Monitoring  

NASA Technical Reports Server (NTRS)

Any attempt to introduce automation into the monitoring of complex physical systems must start from a robust anomaly detection capability. This task is far from straightforward, for a single definition of what constitutes an anomaly is difficult to come by.

Doyle, R. J.

1994-01-01

79

Detection of high tritium activity on the central titanium electrode of a plasma focus device  

Microsoft Academic Search

In this paper a 2-kJ Mather plasma focus device is used to deuterate the top end surface (or tip) of its central titanium electrode to investigate the occurrence of anomalous nuclear reactions in the context of the cold fusion phenomenon. The tip of the central titanium electrode is found to develop at least a few tens of microcuries of tritium

R. K. Rout; M. Spinivasan; A. Shyam; V. Chitra

1991-01-01

80

Capillary isoelectric focusing--useful tool for detection of the biofilm formation in Staphylococcus epidermidis.  

PubMed

The biofilm formation is an important factor of S. epidermidis virulence. Biofilm-positive strains might be clinically more important than biofilm-negative ones. Unlike biofilm-negative staphylococci, biofilm-positive staphylococci are surrounded with an extracellular polysaccharide substance. The presence of this substance on the surface can affect physico-chemical properties of the bacterial cell, including surface charge. 73 S. epidermidis strains were examined for the presence of ica operon, for the ability to form biofilm by Christensen test tube method and for the production of slime by Congo red agar method. Isoelectric points (pI) of these strains were determined by means of Capillary Isoelectric Focusing. The biofilm negative strains focused near pI value 2.3, while the pI values of the biofilm positive strains were near 2.6. Isoelectric point is a useful criterion for the differentiation between biofilm-positive and biofilm-negative S. epidermidis strains. PMID:17157942

Ruzicka, Filip; Horka, Marie; Hola, Veronika; Votava, Miroslav

2007-03-01

81

Detection and differentiation of microbial siderophores by isoelectric focusing and chrome azurol S overlay  

Microsoft Academic Search

Siderophores are microbial, low molecular weight iron-chelating compounds. Fluorescent Pseudomonads produce different, strain-specific fluorescent siderophores (pyoverdines) as well as non-fluorescent siderophores in response to low iron conditions. We present an isoelectric focusing method applicable to unpurified as well as to purified pyoverdine samples where the fluorescent siderophores are visualized under UV illumination. Siderophores from different Pseudomonas sp., amongst which are

Nico Koedam; Etienne Wittouck; Ahmed Gaballa; Anja Gillis; Monica Höfte; Pierre Cornelis

1994-01-01

82

Ultrasound-induced hyperthermia for the spatio-temporal control of gene expression in bone repair  

NASA Astrophysics Data System (ADS)

Spatial and temporal control over the expression of growth/differentiation factors is of great interest for regeneration of bone, but technologies capable of providing tight and active control over gene expression remain elusive. We propose the use of focused ultrasound for the targeted activation of heat shock-sensitive expression systems in engineered bone. We report in vitro results with cells that express firefly luciferase (fLuc) under the control of a heat shock protein promoter. Cells were embedded in fibrin scaffolds and exposed to focused ultrasound, using a custom 3.3MHz transducer (focal length 4", f-number 1.33", focal dimension 1.2mm lateral FWHM) in CW mode for 2-20 minutes at intensities ISPTA=120-440 W/cm2. The kinetics of ultrasound-mediated activation of the cells was compared with that of strictly thermal activation. Bioluminescence imaging revealed fLuc expression in an area >=2.5mm in diameter at the position of the ultrasound focus, and the diameter and intensity of the signal increased with the amplitude of the acoustic energy. We also found that ultrasound activated fLuc expression with substantially shorter exposures than thermal activation. Our results demonstrate the potential for focused ultrasound to selectively activate the expression of a gene of interest in an engineered tissue and suggest that focused ultrasound activates the heat shock pathway by a combination of thermal and non-thermal mechanisms.

Wilson, Christopher; Padilla, Frédéric; Zhang, Man; Vilaboa, Nuria; Kripfgans, Oliver; Fowlkes, Brian; Franceschi, Renny

2012-10-01

83

Detection of Silver Nanoparticles inside Marine Diatom Thalassiosira pseudonana by Electron Microscopy and Focused Ion Beam  

PubMed Central

In the following article an electron/ion microscopy study will be presented which investigates the uptake of silver nanoparticles (AgNPs) by the marine diatom Thalassiosira pseudonana, a primary producer aquatic species. This organism has a characteristic silica exoskeleton that may represent a barrier for the uptake of some chemical pollutants, including nanoparticles (NPs), but that presents a technical challenge when attempting to use electron-microscopy (EM) methods to study NP uptake. Here we present a convenient method to detect the NPs interacting with the diatom cell. It is based on a fixation procedure involving critical point drying which, without prior slicing of the cell, allows its inspection using transmission electron microscopy. Employing a combination of electron and ion microscopy techniques to selectively cut the cell where the NPs were detected, we are able to demonstrate and visualize for the first time the presence of AgNPs inside the cell membrane.

Pascual Garcia, Cesar; Burchardt, Alina D.; Carvalho, Raquel N.; Gilliland, Douglas; C. Antonio, Diana; Rossi, Francois; Lettieri, Teresa

2014-01-01

84

Agroterrorism targeting livestock: a review with a focus on early detection systems.  

PubMed

Agroterrorism targeting livestock can be described as the intentional introduction of an animal disease agent against livestock with the purpose of causing economic damage, disrupting socioeconomic stability of a country, and creating panic and distress. This type of terrorism can be alluring to terrorists because animal disease agents are easily available. This review addresses the vulnerabilities of the livestock industry to agroterrorism. However, we also show that early detection systems have recently been developed for agroterrorism and deliberate spread of animal pathogens in livestock, including an agroterrorism intelligence cycle, syndromic surveillance programs, and computer-based clinical decision support systems that can be used for early detection of notifiable animal diseases. The development of DIVA-vaccines in the past 10 to 15 years has created, in principle, an excellent response instrument to counter intentional animal disease outbreaks. These developments have made our animal agriculture less vulnerable to agroterrorism. But we cannot relax; there are still many challenges, in particular with respect to integration of first line of defense, law enforcement, and early detection systems for animal diseases. PMID:23971814

Elbers, Armin; Knutsson, Rickard

2013-09-01

85

Capillary Array Isoelectric Focusing With Laser Induced Fluorescence Detection: Milli-pH Unit Resolution and Yoctomole Mass Detection Limits in a 32 Channel System  

PubMed Central

We report a multiplexed capillary electrophoresis system employing an array of 32 capillaries with a micromachined sheath flow cuvette as the detection chamber. The sample streams were simultaneously excited with a 473 nm laser beam, and the fluorescence emission was imaged on a CCD camera with a pair of doublet achromat lens. The instrument produced mass detection limits of 380 ± 120 yoctomoles for fluorescein in zone electrophoresis. Capillary isoelectric focusing of fluorescent standards produced peaks with an average width of 0.0029 ± 0.0008 pH. Capillary coating stability limits the reproducibility of the analysis.

Dada, Oluwatosin O.; Ramsay, Lauren M.; Dickerson, Jane A.; Cermak, Nathan; Jiang, Rong; Zhu, Cuiru; Dovichi, Norman J.

2011-01-01

86

[Tuberculosis control programme for the elderly with special focus on early detection].  

PubMed

1. Epidemiological trend of TB and its diagnosis among the elderly: Masako OHMORI (Research Institute of Tuberculosis, JATA). It is estimated that over 10,000 TB patients will occur among the elderly aged over 75 years of age during 2010 and 2020. Though the new TB patients among the elderly over 65 years of age decreased in number from 1987 to 2001, sputum smear positive patients, which are highly infectious increased by 1.3 times for the same age group, and 2.3 times for that of over 80 years of age. 17.6% of those elderly patients were detected in institutions, either hospitals or nursing homes. These indicate that the elderly will become higher risk of TB for causing early death and infection to others during their admission in the hospitals or nursing homes. 2. Clinical characteristics of TB among the elderly: Nobuhiko NAGATA (Department of Internal Medicine, National Ohmuta Hospital). Analysis of the 93 elderly TB patients shows that TB diagnosis was delayed among the elderly. For TB diagnosis, 43.2% took over 1 month, and 27.3% over 2 months among the patients over 75 years of age, compared to 22.9% and 9.7% respectively for the patients under 65 years. The prognosis was also poor. Of all who died in the hospital during TB treatment, 40.9% (mostly complicated with other diseases) was among the elderly over 75 years, while it was 6.5% among those under 65 years. Complication of dementia delayed the diagnosis. 79.4% of the smear positive patients over 75 years were diagnosed while admitted in a general ward, and 40% had been admitted 2 weeks or more before diagnosis. 3. Use of serological tests for the diagnosis of TB among the elderly: Atsuyuki KURASHIMA (Department of Clinical Research, National Tokyo Hospital). As TB diagnosis is difficult for the elderly due to non-specific appearances of signs/symptoms, X-ray shadows or negative tuberculin reaction, some serological tests, which have been recently developed, can be useful as a supplementary diagnostic tool. One of them is anti-lipoarabinomannan antibody. 74.3% was positive to this among 148 bacteriologically confirmed TB cases; 77.8% for those aged 65 years and above, and 71.1% for those under 65 years. To anti TBGL antibody, 78% of 170 confirmed TB cases were positive; 75% for those aged 65 years and above, 79.8% for those less than 65 years. Multi-lipo antibody developed by Japan BCG Laboratory showed higher sensitivity of 91.5%. GPL-core antibody may increase the sensitivity. 4. Mode of TB detection in nursing homes: Shinji SHISHIDO (Research Institute of Tuberculosis, JATA). 15 elderly TB patients who had been diagnosed in 23 nursing homes in the last 5 years were analyzed. The average age was 80.7 years. 10 were male and 5 were female. 11 were sputum smear positive. The symptoms were fever (8), cough (7), wheezing (2), hemoptysis (1), chest pain (1), body weight loss (1), appetite loss (1). Number of patients by time durations before consulting a doctor of within 2 weeks, 2 weeks to 1 month, 1 to 2 months, 2 to 3 months, 3 to 6 months, and more than 6 months were 6, 1, 1, 3, 2, 2 respectively. The prognosis: 4 died within 10 days after diagnosis, 4 needed examinations for the symptoms but were delayed in diagnosis as they were not admitted due to dementia or disability. The orientation and training to the staff of the nursing homes are needed for early TB diagnosis. 5. Programme for the early detection of TB among the elderly: Tadayuki AHIKO (Murayama Public Health Center, Yamagata Prefecture). Based on the analysis of 138 confirmed TB cases registered in Yamagata Prefecture in 1998, services for early TB detection among the elderly should be 1) periodical chest X-ray examinations by the patients home doctors when underlying high risk diseases such as diabetes or cancer exist, and 2) -sputum examination for the symptomatic patients. A survey to 31 local governments conducting special TB services showed the special screening programme for the bedridden elderly in nursing homes was not so efficient due to low quality of the available X-ray facilities and low

Kajiki, Akira; Ishikawa, Nobukatsu

2004-02-01

87

A study of ultrasound-induced microstreaming in blood vessels of tropical fish.  

PubMed Central

Tails of the tropical fish Xiphophorous maculatus have been studied by light microscopy during irradiation with continuous wave 780 kHz ultrasound. Acoustically-induced microstreaming was observed in blood vessels during irradiation with peak intensities above 1 Wcm-2. The microstreaming took the form of rotation of single blood cells and clusters of a few cells and occurred at positions close to the edges of cartilage rods supporting the tail. Streaming was detected initially in vessels 5-10 micrometers across where it impeded blood flow, and as the blood velocity fell it was also observed in larger vessels 15-30 micrometers across. Measurements of rotation speed showed that streaming velocity increased with intensity. The microstreaming is thought to result from radiation torque created by the complex standing wave field produced by reflection from the irradiation tank window and the cartilage rods, or by vibration of the rods in the sound field.

Martin, C. J.; Pratt, B. M.; Watmough, D. J.

1982-01-01

88

Diagnostic Ultrasound Induced Inertial Cavitation to Non-Invasively Restore Coronary and Microvascular Flow in Acute Myocardial Infarction  

PubMed Central

Ultrasound induced cavitation has been explored as a method of dissolving intravascular and microvascular thrombi in acute myocardial infarction. The purpose of this study was to determine the type of cavitation required for success, and whether longer pulse duration therapeutic impulses (sustaining the duration of cavitation) could restore both microvascular and epicardial flow with this technique. Accordingly, in 36 hyperlipidemic atherosclerotic pigs, thrombotic occlusions were induced in the mid-left anterior descending artery. Pigs were then randomized to either a) ½ dose tissue plasminogen activator (0.5 mg/kg) alone; or same dose plasminogen activator and an intravenous microbubble infusion with either b) guided high mechanical index short pulse (2.0 MI; 5 usec) therapeutic ultrasound impulses; or c) guided 1.0 mechanical index long pulse (20 usec) impulses. Passive cavitation detectors indicated the high mechanical index impulses (both long and short pulse duration) induced inertial cavitation within the microvasculature. Epicardial recanalization rates following randomized treatments were highest in pigs treated with the long pulse duration therapeutic impulses (83% versus 59% for short pulse, and 49% for tissue plasminogen activator alone; p<0.05). Even without epicardial recanalization, however, early microvascular recovery occurred with both short and long pulse therapeutic impulses (p<0.005 compared to tissue plasminogen activator alone), and wall thickening improved within the risk area only in pigs treated with ultrasound and microbubbles. We conclude that although short pulse duration guided therapeutic impulses from a diagnostic transducer transiently improve microvascular flow, long pulse duration therapeutic impulses produce sustained epicardial and microvascular re-flow in acute myocardial infarction.

Xie, Feng; Gao, Shunji; Wu, Juefei; Lof, John; Radio, Stanley; Vignon, Francois; Shi, William; Powers, Jeffry; Unger, Evan; Everbach, E. Carr; Liu, Jinjin; Porter, Thomas R.

2013-01-01

89

Optimization of the Ultrasound-Induced Blood-Brain Barrier Opening  

PubMed Central

Current treatments of neurological and neurodegenerative diseases are limited due to the lack of a truly non-invasive, transient, and regionally selective brain drug delivery method. The brain is particularly difficult to deliver drugs to because of the blood-brain barrier (BBB). The impermeability of the BBB is due to the tight junctions connecting adjacent endothelial cells and highly regulatory transport systems of the endothelial cell membranes. The main function of the BBB is ion and volume regulation to ensure conditions necessary for proper synaptic and axonal signaling. However, the same permeability properties that keep the brain healthy also constitute the cause of the tremendous obstacles posed in its pharmacological treatment. The BBB prevents most neurologically active drugs from entering the brain and, as a result, has been isolated as the rate-limiting factor in brain drug delivery. Until a solution to the trans-BBB delivery problem is found, treatments of neurological diseases will remain impeded. Over the past decade, methods that combine Focused Ultrasound (FUS) and microbubbles have been shown to offer the unique capability of noninvasively, locally and transiently open the BBB so as to treat central nervous system (CNS) diseases. Four of the main challenges that have been taken on by our group and discussed in this paper are: 1) assess its safety profile, 2) unveil the mechanism by which the BBB opens and closes, 3) control and predict the opened BBB properties and duration of the opening and 4) assess its premise in brain drug delivery. All these challenges will be discussed, findings in both small (mice) and large (non-human primates) animals are shown and finally the clinical potential for this technique is shown.

Konofagou, Elisa E.

2012-01-01

90

Modelling ultrasound-induced mild hyperthermia of hyperplasia in vascular grafts  

PubMed Central

Background Expanded polytetrafluoroethylene (ePTFE) vascular grafts frequently develop occlusive neointimal hyperplasia as a result of myofibroblast over-growth, leading to graft failure. ePTFE exhibits higher ultrasound attenuation than native soft tissues. We modelled the selective absorption of ultrasound by ePTFE, and explored the feasibility of preventing hyperplasia in ePTFE grafts by ultrasound heating. Specifically, we simulated the temperature profiles of implanted grafts and nearby soft tissues and blood under ultrasound exposure. The goal was to determine whether ultrasound exposure of an ePTFE graft can generate temperatures sufficient to prevent cell growth on the graft without damaging nearby soft tissues and blood. Methods Ultrasound beams from two transducers (1.5 and 3.2 MHz) were simulated in two graft/tissue models, with and without an intra-graft cellular layer mimicking hyperplasia, using the finite-difference time-domain (FDTD) method. The resulting power deposition patterns were used as a heat source for the Pennes bioheat equation in a COMSOL® Multiphysics heat transfer model. 50°C is known to cause cell death and therefore the transducer powers were adjusted to produce a 13°C temperature rise from 37°C in the ePTFE. Results Simulations showed that both the frequency of the transducers and the presence of hyperplasia significantly affect the power deposition patterns and subsequent temperature profiles on the grafts and nearby tissues. While neither transducer significantly raised the temperature of the blood, the 1.5-MHz transducer was less focused and heated larger volumes of the graft and nearby soft tissues than the 3.2-MHz transducer. The presence of hyperplasia had little effect on the blood's temperature, but further increased the temperature of the graft and nearby soft tissues in response to either transducer. Skin cooling and blood flow play a significant role in preventing overheating of the native tissues. Conclusions Modelling shows that ultrasound can selectively heat ePTFE grafts and produce temperatures that cause cell death on the graft. The temperature increase in blood is negligible and that in the adjacent soft tissues may be minimized by skin cooling and using appropriate transducers. Therefore, ultrasound heating may have the potential to reduce neointimal hyperplasia and failure of ePTFE vascular grafts.

2011-01-01

91

Ultrasound-induced thermal therapy of hyperplasia in ringed expanded polytetrafluoroethylene (eptfe) access grafts  

NASA Astrophysics Data System (ADS)

Hemodialysis vascular access, the interface between a dialysis patient and a dialysis machine, is quite literally the lifeblood of a patient's health. Vascular access dysfunction is the leading cause of hospitalization in hemodialysis patients. The occlusive growth of neointimal hyperplasia (NH) in expanded polytetrafluoroethylene (ePTFE) ringed grafts is the primary cause of failure. To further develop a proposed thermal ultrasound treatment to reduce or prevent NH in arteriovenous vascular grafts, the acoustic properties of ePTFE were studied in water and alcohol solutions. Previous reports of ePTFE acoustic properties are critiqued. It was found that the acoustic transmission and attenuation through ePTFE, and therefore the potential for an ultrasound-based therapy for NH, are heavily dependent on the medium in which the graft is immersed, suggesting that the acoustic properties of implanted grafts will change as grafts mature in vivo. The acoustic impedance and attenuation of water-soaked ePTFE were 0.478 +/- 1.43 x 10-2 MRayl and 1.78 +/- 0.111 Np/cm*MHz, respectively, while the acoustic impedance and attenuation of ePTFE in alcohol were 1.49 +/- 0.149 MRayl and 0.77 +/- 1.1 x 10-2 Np/cm*MHz, respectively. The use of focused ultrasound to heat implanted ringed ePTFE grafts was numerically modeled from 1.35- and 1.443-MHz transducers for in vitro geometries. Power deposition and heating, in turn, differed by an order of magnitude between various graft acoustic properties. Graft rings were predicted to be substantial absorbing and scattering features. In vitro phantom models were constructed: one with and one without thermocouples. At 1 W of acoustic power, the maximum temperature rise was 8? C. The thermocouple model containing a water-soaked graft did not experience heating in the far graft wall. The MRTI model confirmed that the graft rings are an absorbing/scattering feature. Heating was not prevented in the presence of water flow through the graft. Water was not heated significantly. Overall, results suggest ultrasound exposure can be used to generate temperature rises corresponding with the potential prevention or inhibition of NH in ringed ePTFE vascular grafts. A hybrid therapeutic/diagnostic transducer design with a therapeutic semi-annular array surrounding a diagnostic linear array is presented. Compared to a solid transducer of the same dimensions, there were only marginal aberrations in the focal plane. Numerical optimization of the element drive configuration indicated that the least distorted focal plane was produced by uniform phase and magnitude at each element.

Query, Michael Earl

92

Optical imaging of high-frequency focused ultrasonic field using a Nomarski interferometer coupled with multichannel lock-in detection  

NASA Astrophysics Data System (ADS)

We present a nondestructive optical technique for quantitatively imaging a focused ultrasonic field in continuous-wave mode within clear media. We used a Nomarski interferometer configuration coupled with a couple charge device array and multichannel lock-in detection. A two-dimensional full-field image of pressure amplitude can be obtained in only one acquisition. This method was experimentally demonstrated with a high-frequency ultrasonic transducer and experimental measurements of acoustic pressure obtained at 27 MHz. This technique is very interesting because it does not introduce any disturbance in the ultrasonic field and does not need any scanning mechanisms to acquire images. It can be useful for probing high-frequency acoustic fields and for calibrating HF-piezo-electric transducers.

Baït, Lyès; Femmam, Smain; Claude Boccara, A.; Roger, Jean Paul

2012-07-01

93

Detection of AMP-activated protein kinase ?1 by isoelectric focusing in sera of patients with metabolic diseases.  

PubMed

The aim of this study is to determine by isoelectric focusing the level of AMPK?1, an energy sensor, in sera of patients who are in energy-demanding situation. After Western blotting, detection was performed with specific antibodies against AMPK? and its phosphorylated form. To evaluate the effect of weight loss on AMPK, sera from 24 patients were collected before and after intragastric balloon insertion over a 16-week follow-up period. Compared to baseline, all patients showed postoperatively an increase of AMPK. Patients with ischemic heart, with inflammatory bowel disease, with chronic undernutrition or with hepatic diseases were examined. Compared to control subjects, the majority of them showed a significant increase of AMPK. These results suggest that serum AMPK may have a potential for diagnosis of several metabolic diseases. However, this has to be confirmed by further studies with additional biomarkers and with more specific techniques. PMID:22930535

Malvoisin, Etienne

2012-09-01

94

Investigation of the pH gradient formation and cathodic drift in microchip isoelectric focusing with imaged UV detection.  

PubMed

This paper reports the protein analysis by using microchip IEF carried on an automated chip system. We herein focused on two important topics of microchip IEF, the pH gradient and cathodic drift. The computer simulation clarified that the EOF could delay the establishment of pH gradient and move the carrier ampholytes (CAs) to cathode, which probably caused a cathodic drift to happen. After focusing, the peak positions of components in a calibration kit with broad pI were plotted against their pI values to know the actual pH gradient in a microchannel varying time. It was found that the formed pH gradient was stable, not decayed after readily steady state, and migrated to cathode at a rate of 10.0??m/s that determined by the experimental conditions such as chip material, internal surface coating and field strength. The theoretical pH gradient was parallel with the actual pH gradient, which was demonstrated in two types of microchip with different channel lengths. No compression of pH gradient was observed when 2% w/v hydroxypropyl methyl cellulose was added in sample and electrolytes. The effect of CAs concentration on current and cathodic drift was also explored. With the current automatic chip system, the calculated peak capacity was 23-48, and the minimal pI difference was 0.20-0.42 for the used single channel microchip with the effective length of 40.5?mm. The LOD for the analysis of CA-I and CA-II was around 0.32??g/mL by using normal imaged UV detection, the detected amount is ca. 0.07?ng. PMID:20925054

Xu, Zhongqi; Okabe, Noboru; Arai, Akihiro; Hirokawa, Takeshi

2010-10-01

95

Two-dimensional capillary electrophoresis: capillary isoelectric focusing and capillary zone electrophoresis with laser-induced fluorescence detection  

PubMed Central

Capillary isoelectric focusing and capillary zone electrophoresis are coupled with laser-induced fluorescence detection to create an ultrasensitive two-dimensional separation method for proteins. In this method, two capillaries are joined through a buffer filled interface. Separate power supplies control the potential at the injection end of the first capillary and at the interface; the detector is held at ground potential. Proteins are labeled with the fluorogenic reagent Chromeo P503, which preserves the isoelectric point of the labeled protein. The labeled proteins were mixed with ampholytes and injected into the first dimension capillary. A focusing step was performed with the injection end of the capillary at high pH and the interface at low pH. To mobilize components, the interface was filled with a high pH buffer, which was compatible with the second dimension separation. A fraction was transferred to the second dimension capillary for separation. The process of fraction transfer and second dimension separation was repeated two dozen times. The separation produced a spot capacity of 125.

Dickerson, Jane A.; Ramsay, Lauren M.; Dada, Oluwatosin O.; Cermak, Nathan

2011-01-01

96

Rapid and high-resolution glycoform profiling of recombinant human erythropoietin by capillary isoelectric focusing with whole column imaging detection.  

PubMed

Human erythropoietin (hEPO) is a glycoprotein hormone produced primarily by the kidney, which stimulates red blood cell production. Recombinant human erythropoietin (rhEPO), generally produced in Chinese hamster ovary (CHO) cells, can be used as not only a therapeutic protein but also a doping agent in sports. Profiling of EPO glycoforms is a critical means for quality control in pharmaceutical industrial and anti-doping analysis of misuse in sports. However, the existing methods for the analysis of EPO are associated with either time consuming or poor resolution. In this work, a rapid and high-resolution glycoform profiling method was presented based on capillary isoelectric focusing (cIEF) with whole column imaging detection (WCID). Experimental conditions that influence the separation were investigated. Under optimized conditions, rhEPO from three different sources were resolved into distinct populations within 5 min with excellent reproducibility. As compared with existing methods, the presented method exhibited the advantages of speed and high resolution. If combined with an effective sample enrichment step and a much more sensitive WCID version, the method can be a potential alternative for the detection of rhEPO misuse in sports. PMID:18374347

Dou, Peng; Liu, Zhen; He, Jiangang; Xu, Jing-Juan; Chen, Hong-Yuan

2008-05-01

97

First molecular detection of Leishmania major within naturally infected Phlebotomus salehi from a zoonotic cutaneous leishmaniasis focus in southern Iran.  

PubMed

Human cutaneous leishmaniasis (CL) is a major notifiable public health problem in many parts of Iran. It is often caused by the zooflagellate parasite Leishmania major which is mainly transmitted by the bites of female phlebotomine sandflies belonging to the genus Phlebotomus (Diptera: Psychodidae). The annual incidence of CL in Fars province, southern Iran, was about 108-144 in 2007. The leishmanial infections of wild sandflies that may act as vectors were thus investigated at an endemic focus in this province. In all 330 female Phlebotomus sandflies were screened for the detection of Leishmania-specific kinetoplast DNA (kDNA) by polymerase chain reaction (PCR) methods. A two stage nested PCR protocol was used to establish the identity of Leishmania major species in naturally infected sandflies. The L. major kDNA was detected in 18 (5.5%) individual sandflies which belonged to four different Phlebotomus species (Phlebotomus papatasi, Phlebotomus salehi, Phlebotomus sergenti and P. major group). For the first time, one naturally infected P. salehi specimen contained the kDNA of the protozoan parasite, L. major, with a main band of 560 base pairs identified using the nested PCR method. It seems most likely therefore that P. salehi is potentially a rare sylvatic vector of L. major parasites in parts of this province. This is the first combined morphological and molecular studies of P. salehi in Iran. PMID:22543597

Azizi, K; Fakoorziba, M R; Jalali, M; Moemenbellah-Fard, M D

2012-03-01

98

Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device  

Microsoft Academic Search

A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two

T. K. Borthakur; N. Talukdar; N. K. Neog; C. V. S. Rao; A. Shyam

2011-01-01

99

Rapid Focused Sequencing: A Multiplexed Assay for Simultaneous Detection and Strain Typing of Bacillus anthracis, Francisella tularensis, and Yersinia pestis  

PubMed Central

Background The intentional release of Bacillus anthracis in the United States in 2001 has heightened concern about the use of pathogenic microorganisms in bioterrorism attacks. Many of the deadliest bacteria, including the Class A Select Agents Bacillus anthracis, Francisella tularensis, and Yersinia pestis, are highly infectious via the pulmonary route when released in aerosolized form. Hence, rapid, sensitive, and reliable methods for detection of these biothreats and characterization of their potential impact on the exposed population are of critical importance to initiate and support rapid military, public health, and clinical responses. Methodology/Principal Findings We have developed microfluidic multiplexed PCR and sequencing assays based on the simultaneous interrogation of three pathogens per assay and ten loci per pathogen. Microfluidic separation of amplified fluorescently labeled fragments generated characteristic electrophoretic signatures for identification of each agent. The three sets of primers allowed significant strain typing and discrimination from non-pathogenic closely-related species and environmental background strains based on amplicon sizes alone. Furthermore, sequencing of the 10 amplicons per pathogen, termed “Rapid Focused Sequencing,” allowed an even greater degree of strain discrimination and, in some cases, can be used to determine virulence. Both amplification and sequencing assays were performed in microfluidic biochips developed for fast thermal cycling and requiring 7 µL per reaction. The 30-plex sequencing assay resulted in genotypic resolution of 84 representative strains belonging to each of the three biothreat species. Conclusions/Significance The microfluidic multiplexed assays allowed identification and strain differentiation of the biothreat agents Bacillus anthracis, Francisella tularensis, and Yersinia pestis and clear discrimination from closely-related species and several environmental background strains. The assays may be extended to detect a large number of pathogens, are applicable to the evaluation of both environmental and clinical samples, and have the potential to be applied in military, public health, and clinical diagnostic settings.

Zolotova, Anna; Tan, Eugene; Selden, Richard F.

2013-01-01

100

In vivo multispectral, multiparameter, photoacoustic lymph flow cytometry with natural cell focusing, label-free detection and multicolor nanoparticle probes.  

PubMed

Compared with blood tests, cell assessment in lymphatics is not well-established. The goal of this work was to develop in vivo lymph tests using the principles of flow cytometry. Cells in living animals were counted by laser (420-2,300 nm) generation of photoacoustic (PA) signals in individual cells hydrodynamically focused by lymph valves into a single file flow, and using endogenous absorption as intrinsic cell-specific markers, or gold nanorods, nanoshells, and carbon nanotubes as multicolor probes. PA data were verified by high-speed transmission, photothermal, and fluorescent imaging. Counting of melanoma and immune-related cells in normal, apoptotic, and necrotic states in lymphatics in vivo was demonstrated to have the unprecedented sensitivity as one metastatic cell among millions of white blood cells. The time-resolved PA spectral identification of flowing cells was achieved using multicolor labels and laser pulses of different wavelengths and time delays. Multiparameter, noninvasive, portable flow cytometer can be used for preclinical studies on animals with the potential of translation to humans for in vivo PA mapping of colorless lymph vessels and sentinel nodes with simultaneous single cell detection and metastasis assessment without labeling or use of contrast dyes and/or novel low-toxic multicolor probes with different absorption spectra. PMID:18677768

Galanzha, Ekaterina I; Shashkov, Evgeny V; Tuchin, Valery V; Zharov, Vladimir P

2008-10-01

101

The Dense Plasma Focus Opportunities in Detection of Hidden Objects by Using Nanosecond Impulse Neutron Inspection System (NINIS)  

SciTech Connect

Dense Plasma Focus device is proposed for use as a neutron source to generate very powerful pulses of neutrons in the nanosecond (ns) range of its duration. Our devices PF-6, recently put into operation at the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland, and PF-10 belonging to the Institute for Theoretical and Experimental Physics, Moscow, Russia, have energy storages in its capacitor banks 7.4 kJ and 13 kJ as a maximum. Operated with the DPF chambers of a special design they have a current maximum up to {approx}760 kA with a quarter period of the discharge equal to 1 microsecond. They generate circa 109 of 2.5-MeV neutrons in one pulse of congruent with 10-ns duration when working with deuterium, what permit to expect 1011 14-MeV neutrons at their operation with DT-mixture. This feature gives a principal possibility to create a ''single-shot detection system'' for interrogation of hidden objects. It means that all necessary information will be received during a single bright pulse of neutrons having duration in a nanosecond range by means of the time-of-flight technique with a short flight base. It might be a base for the creation of the Nanosecond Impulse Neutron Inspection System (NINIS). These characteristics of the neutron source open a number of opportunities while interrogation time in this case would now depend only on the data-processing system.

Gribkov, V.; Karpinski, L.; Miklaszewski, R.; Paduch, M.; Scholz, M.; Strzyzewski, P.; Tomaszewski, K. [A.I. Alikhanov Institute for Theoretical and Experimental Physics, ul. Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Dubrovsky, A. [Institute of Plasma Physics and Laser Microfusion, ul. Hery 23, Warsaw 01-497 (Poland)

2006-12-04

102

Detection systems for mass spectrometry imaging: a perspective on novel developments with a focus on active pixel detectors.  

PubMed

Instrumental developments for imaging and individual particle detection for biomolecular mass spectrometry (imaging) and fundamental atomic and molecular physics studies are reviewed. Ion-counting detectors, array detection systems and high mass detectors for mass spectrometry (imaging) are treated. State-of-the-art detection systems for multi-dimensional ion, electron and photon detection are highlighted. Their application and performance in three different imaging modes--integrated, selected and spectral image detection--are described. Electro-optical and microchannel-plate-based systems are contrasted. The analytical capabilities of solid-state pixel detectors--both charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) chips--are introduced. The Medipix/Timepix detector family is described as an example of a CMOS hybrid active pixel sensor. Alternative imaging methods for particle detection and their potential for future applications are investigated. PMID:23239313

Jungmann, Julia H; Heeren, Ron M A

2013-01-15

103

Detection of unlabeled particles in the low micrometer size range using light scattering and hydrodynamic 3D focusing in a microfluidic system.  

PubMed

In this paper, we describe a microfluidic device composed of integrated microoptical elements and a two-layer microchannel structure for highly sensitive light scattering detection of micro/submicrometer-sized particles. In the two-layer microfluidic system, a sample flow stream is first constrained in the out-of-plane direction into a narrow sheet, and then focused in-plane into a small core region, obtaining on-chip three-dimensional (3D) hydrodynamic focusing. All the microoptical elements, including waveguides, microlens, and fiber-to-waveguide couplers, and the in-plane focusing channels are fabricated in one SU-8 layer by standard photolithography. The channels for out-of-plane focusing are made in a polydimethylsiloxane (PDMS) layer by a single cast using a SU-8 master. Numerical and experimental results indicate that the device can realize 3D hydrodynamic focusing reliably over a wide range of Reynolds numbers (0.5 < Re < 20). Polystyrene particles of three sizes (2, 1, and 0.5 ?m) were measured in the microfluidic device with integrated optics, demonstrating the feasibility of this approach to detect particles in the low micrometer size range by light scattering detection. PMID:22740459

Zhuang, Guisheng; Jensen, Thomas G; Kutter, Jörg P

2012-07-01

104

ZnS/ 6Li scintillation material as an alternative to 6Li-glass scintillators for neutron detection in time focusing geometry  

NASA Astrophysics Data System (ADS)

As an alternative of using 6Li-glass scintillators for neutron detection in time focusing geometry the effects of ZnS/ 6Li scintillation material on the measuring efficiency will be discussed on example of the high resolution RTOF device FSS at GKSS Geesthacht, Germany.

Kreyssig, A.; Irmer, K.; Hartung, U.

1994-09-01

105

A pulsed THz imaging system with a line focus and a balanced 1-D detection scheme with two industrial CCD line-scan cameras.  

PubMed

We present a pulsed THz Imaging System with a line focus intended to speed up measurements. A balanced 1-D detection scheme working with two industrial line-scan cameras is used. The instrument is implemented without the need for an amplified laser system, increasing the industrial applicability. The instrumental characteristics are determined. PMID:20389575

Wiegand, Christian; Herrmann, Michael; Bachtler, Sebastian; Klier, Jens; Molter, Daniel; Jonuscheit, Joachim; Beigang, René

2010-03-15

106

High-precision topography measurement through accurate in-focus plane detection with hybrid digital holographic microscope and white light interferometer module.  

PubMed

High-precision topography measurement of micro-objects using interferometric and holographic techniques can be realized provided that the in-focus plane of an imaging system is very accurately determined. Therefore, in this paper we propose an accurate technique for in-focus plane determination, which is based on coherent and incoherent light. The proposed method consists of two major steps. First, a calibration of the imaging system with an amplitude object is performed with a common autofocusing method using coherent illumination, which allows for accurate localization of the in-focus plane position. In the second step, the position of the detected in-focus plane with respect to the imaging system is measured with white light interferometry. The obtained distance is used to accurately adjust a sample with the precision required for the measurement. The experimental validation of the proposed method is given for measurement of high-numerical-aperture microlenses with subwavelength accuracy. PMID:24787417

Li?ewski, Kamil; Tomczewski, S?awomir; Kozacki, Tomasz; Kostencka, Julianna

2014-04-10

107

Windows of detection of lorazepam in urine, oral fluid and hair, with a special focus on drug-facilitated crimes.  

PubMed

The purported lowering of sex opposition, coupled with a possible abrupt unconsciousness-inducing effect and ease of administration in spiked drinks have resulted in the use of hypnotics in cases of drug-facilitated offense. Among these compounds, lorazepam possesses amnesic properties and can impair an individual rapidly. The chances to detect this substance increase if the most sensitive methods are used and if the biological fluid which allows the longest possible detection time is available. In order to document the window of detection of lorazepam, we have orally administered 2.5 mg of the drug to three volunteers and collected oral fluid (n = l) over 8 h, urine (n = 2) over 144 h and hair (n = 3) 4 weeks after exposure. Lorazepam was analyzed by LC-MS/MS after alkalinisation (to pH 8.4 with phosphate buffer) and extraction by dichloromethane/diethyl ether in presence of diazepam-d5, used as internal standard. Reversed-phase separation on a XTerra C18 column was achieved in 12 min, under gradient conditions. Molecular ions (m/z 321 and 290 for lorazepam and the IS, respectively) were selected in Ql and the corresponding daughter ions (m/z 303 and 275 for lorazepam and m/z 154 and 198 for the IS) were detected in Q3 after collision with argon. Urine tested positive for lorazepam over 144 h (2-4 ng/ml), with a peak detected after 24 h exposure (411-880 ng/ml). Oral fluid tested positive for lorazepam over 8 h (0.7 ng/ml). Despite a limit of quantitation at 1 pg/mg, we were unable to detect a single lorazepam dose in hair, contrarily to most other benzodiazepines that are detectable. Therefore, in case of drug-facilitated crimes involving lorazepam, urine appears as the best specimen to document exposure, particularly if LC-MS/MS is used. PMID:15451084

Kintz, Pascal; Villain, Marion; Cirimele, Vincent; Pépin, Gilbert; Ludes, Bertrand

2004-10-29

108

Space-time Bayesian small area disease risk models: development and evaluation with a focus on cluster detection  

PubMed Central

This paper extends the spatial local-likelihood model and the spatial mixture model to the space-time (ST) domain. For comparison, a standard random effect space-time (SREST) model is examined to allow evaluation of each model’s ability in relation to cluster detection. To pursue this evaluation, we use the ST counterparts of spatial cluster detection diagnostics. The proposed criteria are based on posterior estimates (e.g., misclassification rate) and some are based on post-hoc analysis of posterior samples (e.g., exceedance probability). In addition, we examine more conventional model fit criteria including mean square error (MSE). We illustrate the methodology with a real ST dataset, Georgia throat cancer mortality data for the years 1994–2005, and a simulated dataset where different levels and shapes of clusters are embedded. Overall, it is found that conventional SREST models fair well in ST cluster detection and in goodness-of-fit, while for extreme risk detection the local likelihood ST model does best.

Lawson, Andrew B.

2010-01-01

109

A new multichannel time reversal focusing method for circumferential Lamb waves and its applications for defect detection in thick-walled pipe with large-diameter.  

PubMed

This paper proposes a new multichannel time reversal focusing (MTRF) method for circumferential Lamb waves which is based on modified time reversal algorithm and applies this method for detecting different kinds of defects in thick-walled pipe with large-diameter. The principle of time reversal of circumferential Lamb waves in pipe is presented along with the influence from multiple guided wave modes and propagation paths. Experimental study is carried out in a thick-walled and large-diameter pipe with three artificial defects, namely two axial notches on its inner and outer surface respectively, and a corrosion-like defect on its outer surface. By using the proposed MTRF method, the multichannel signals focus at the defects, leading to the amplitude improvement of the defect scattered signal. Besides, another energy focus arises in the direct signal due to the partial compensation of dispersion and multimode of circumferential Lamb waves, alongside the multichannel focusing, during MTRF process. By taking the direct focus as a time base, accurate defect localization is implemented. Secondly, a new phenomenon is exhibited in this paper that defect scattered wave packet appears just before the right boundary of truncation window after time reversal, and to which two feasible explanations are given. Moreover, this phenomenon can be used as the theoretical basis in the determination of defect scattered waves in time reversal response signal. At last, in order to detect defects without prior knowing their exact position, a large-range truncation window is used in the proposed method. As a result, the experimental operation of MTRF method is simplified and defect detection and localization are well accomplished. PMID:24877582

Liu, Zenghua; Xu, Qinglong; Gong, Yu; He, Cunfu; Wu, Bin

2014-09-01

110

Two-dimensional FDTD analysis of a pulsed microwave confocal system for breast cancer detection: fixed-focus and antenna-array sensors  

Microsoft Academic Search

A novel focused active microwave system is investigated for detecting tumors in the breast. In contrast to X-ray and ultrasound modalities, the method reviewed here exploits the breast-tissue physical properties unique to the microwave spectrum, namely, the translucent nature of normal breast tissues and the high dielectric contrast between malignant tumors and surrounding lesion-free normal breast tissues. The system uses

Susan C. Hagness; Allen Taflove; Jack E. Bridges

1998-01-01

111

Exploring recruitment barriers and facilitators in early cancer detection trials: the use of pre-trial focus groups  

PubMed Central

Background Recruiting to randomized controlled trials is fraught with challenges; with less than one third recruiting to their original target. In preparation for a trial evaluating the effectiveness of a blood test to screen for lung cancer (the ECLS trial), we conducted a qualitative study to explore the potential barriers and facilitators that would impact recruitment. Methods Thirty two people recruited from community settings took part in four focus groups in Glasgow and Dundee (UK). Thematic analysis was used to code the data and develop themes. Results Three sub-themes were developed under the larger theme of recruitment strategies. The first of these themes, recruitment options, considered that participants largely felt that the invitation to participate letter should come from GPs, with postal reminders and face-to-face reminders during primary care contacts. The second theme dealt with understanding randomization and issues related to the control group (where bloods were taken but not tested). Some participants struggled with the concept or need for randomization, or for the need for a control group. Some reported that they would not consider taking part if allocated to the control group, but others were motivated to take part even if allocated to the control group by altruism. The final theme considered perceived barriers to participation and included practical barriers (such as flexible appointments and reimbursement of travel expenses) and psychosocial barriers (such as feeling stigmatized because of their smoking status and worries about being coerced into stopping smoking). Conclusions Focus groups provided useful information which resulted in numerous changes to proposed trial documentation and processes. This was in order to address participants information needs, improve comprehension of the trial documentation, enhance facilitators and remove barriers to participation. The modifications made in light of these findings may enhance trial recruitment and future trials may wish to consider use of pretrial focus groups.

2014-01-01

112

Saving cells from ultrasound-induced apoptosis: quantification of cell death and uptake following sonication and effects of targeted calcium chelation  

PubMed Central

Applications of ultrasound for non-invasive drug and gene delivery have been limited by associated cell death due to sonication. In this study, we sought to quantify the distribution of cellular bioeffects caused by low-frequency ultrasound (24 kHz) and test the hypothesis that Ca2+ chelation after sonication can shift this distribution by saving cells from death by apoptosis. Using flow cytometry, we quantitatively categorized sonicated cells among four populations: (1) cells that appear largely unaffected, (2) cells reversibly permeabilized, (3) cells rendered nonviable during sonication and (4) cells that appear to be viable shortly after sonication, but later undergo apoptosis and die. By monitoring cells for 6 h after ultrasound exposure, we found that up to 15% of intact cells fell into this final category. Those apoptotic cells initially had the highest levels of uptake of a marker compound, calcein; also had highly elevated levels of intracellular Ca2+; and contained an estimated plasma membrane wound radius of 100 – 300 nm. Finally, we showed that chelation of intracellular Ca2+ after sonication reduced apoptosis by up to 44%, thereby providing a strategy to save cells. We conclude that cells can be saved from ultrasound-induced death by appropriate selection of ultrasound conditions and Ca2+ chelation after sonication.

Hutcheson, J.D.; Schlicher, R.K.; Hicks, H.K.; Prausnitz, M.R.

2010-01-01

113

Attention focusing in a sit-and-wait forager: a spider controls its prey-detection ability in different web sectors by adjusting thread tension.  

PubMed

Focusing attention is a way for animals to search for and to obtain food efficiently. This study examines whether a sit-and-wait forager, the orb-web spider Cyclosa octotuberculata, focuses its attention on limited foraging areas. Video records of foraging activity revealed that the spiders detected prey trapped in the west and east sectors of their web less frequently than prey trapped in the north and south sectors. Comparison of photos of the web hub area with and without spiders present revealed that the spiders pulled radii towards the centre when waiting for prey. Radius pulling is stronger in the north and south web sectors than in the west and east sectors, possibly causing more tension in radii running vertically. Experimental manipulation indicated that the spiders responded to prey quicker when thread tension was increased. The results suggest that C. octotuberculata focus their attention on the web areas above and below the spider by adjusting the tension in web threads; and this causes higher prey detection rates in these areas. PMID:19812081

Nakata, Kensuke

2010-01-01

114

First detection of Leishmania infantum DNA in wild caught Phlebotomus papatasi in endemic focus of cutaneous leishmaniasis, South of Iran  

PubMed Central

Objective To identify the vectors and reservoirs of cutaneous leishmaniasis in the endemic focus of Farashband, Fars Province, South of Iran. Methods Sticky papers and Sherman trap were used for collection of sand flies and rodents, respectively. Polymerase chain reaction (PCR) of kDNA, ITS1-rDNA were used for identification of Leishmania parasite in sand flies as well as rodents. Results Totally 2?010 sand flies were collected and the species of Phlebotomus papatasi Scopoli was the common specimen in outdoors and indoors places. PCR technique was employed on 130 females of Phlebotomus papatasi. One of them (0.76%) was positive to parasite Leishmania major (L. major) and one specimen (0.76%) was positive to Leishmania infantum. Microscopic investigation on blood smear of the animal reservoirs for amastigote parasites revealed 16 (44%) infected Tatera indica. Infection of them to L. major was confirmed by PCR against kDNA loci of the parasite. Conclusions The results indicated that Phlebotomus papatasi was the dominant species circulating two species of parasites including L. major and Leishmania infantum among human and reservoirs. Furthermore, Tatera indica is the only main host reservoir for maintenance of the parasite source in the area.

Yavar, Rassi; Hadi, Karami; Reza, Abai Mohammad; Mohebali, M; Hasan, Bakshi; Ali, Oshaghi Mohammad; Sina, Rafizadeh; Habib, Bagherpoor Hagigi; Abodolrahim, Hosseini; Manuchehr, Gholami

2013-01-01

115

Very focused expulsion of pore fluid along the western Nankai accreionary complex detected by closely-spaced heat flow measurements  

NASA Astrophysics Data System (ADS)

During the KR02-10 cruise onboard R/V KAIREI, JAMSTEC, intensive heat flow measurements were carried out across the western and middle Nankai Trough areas, in order to reveal thermal and hydrological process across the frontal thrust and the Large Thrust Slice Zone (LTSZ). Previous heat flow data suggest that the Nankai accretionary complex is basically thermal-conduction dominant, except for strongly channelized flow along the faults. Heat flow was measured using two types of geothermal probes: a 4.5m geothermal probe lowered from the ship, and two 60cm probes manipulated by ROV KAIKO. Probe positions were controlled using SSBL acoustic navigation with the accuracy of 30-70 m. We obtained 19 heat flow data across the second frontal thrust off Muroto. Heat flow is highest at the base of the second frontal thrust. Maximum heat flow reaches up to 280 mW/m2 and its width is probably less than 50 m. We observed no indication of seepage activity at this site. Upslope we found a cold seep site, which was distributed along a topographic contour of 4620 m. Although we measured heat flow in the middle of seep site, no heat flow anomaly was detected. We obtained 12 heat flow data across the lower part of LTSZ off Muroto. Two local heat flow anomalies of up to 250 mW/m2 were detected, both of which are related to cold seep activities. The amplitude of heat flow anomalies is similar to that observed in the frontal thrust area, although the basal heat flow here, 60-80 mW/m2, is much lower that in the frontal thrust area. Also, the width of the anomaly seems similar to frontal thrust area. These data indicates that fluid flow is restricted within the fault or in the hanging wall, and otherwise the thermal regime in the accretionary complex is conduction dominant. On the other hand, difference in heat flow anomaly locations between two areas may provide insights into the maturity of cold seep activity and the thrust as fluid conduits.

Kinoshita, M.; Goto, S.; Gulick, S. P.; Mikada, H.

2002-12-01

116

Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device.  

PubMed

A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made. PMID:22047294

Borthakur, T K; Talukdar, N; Neog, N K; Rao, C V S; Shyam, A

2011-10-01

117

New pediatric vision screener employing polarization-modulated, retinal-birefringence-scanning-based strabismus detection and bull's eye focus detection with an improved target system: opto-mechanical design and operation.  

PubMed

ABSTRACT. Amblyopia ("lazy eye") is a major public health problem, caused by misalignment of the eyes (strabismus) or defocus. If detected early in childhood, there is an excellent response to therapy, yet most children are detected too late to be treated effectively. Commercially available vision screening devices that test for amblyopia's primary causes can detect strabismus only indirectly and inaccurately via assessment of the positions of external light reflections from the cornea, but they cannot detect the anatomical feature of the eyes where fixation actually occurs (the fovea). Our laboratory has been developing technology to detect true foveal fixation, by exploiting the birefringence of the uniquely arranged Henle fibers delineating the fovea using retinal birefringence scanning (RBS), and we recently described a polarization-modulated approach to RBS that enables entirely direct and reliable detection of true foveal fixation, with greatly enhanced signal-to-noise ratio and essentially independent of corneal birefringence (a confounding variable with all polarization-sensitive ophthalmic technology). Here, we describe the design and operation of a new pediatric vision screener that employs polarization-modulated, RBS-based strabismus detection and bull's eye focus detection with an improved target system, and demonstrate the feasibility of this new approach. PMID:24911020

Irsch, Kristina; Gramatikov, Boris I; Wu, Yi-Kai; Guyton, David L

2014-06-01

118

Magnetic Resonance Thermometry at 7T for Real-Time Monitoring and Correction of Ultrasound Induced Mild Hyperthermia  

PubMed Central

While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (?7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1°C.

Fite, Brett Z.; Liu, Yu; Kruse, Dustin E.; Caskey, Charles F.; Walton, Jeffrey H.; Lai, Chun-Yen; Mahakian, Lisa M.; Larrat, Benoit; Dumont, Erik; Ferrara, Katherine W.

2012-01-01

119

Magnetic resonance thermometry at 7T for real-time monitoring and correction of ultrasound induced mild hyperthermia.  

PubMed

While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (?7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1°C. PMID:22536396

Fite, Brett Z; Liu, Yu; Kruse, Dustin E; Caskey, Charles F; Walton, Jeffrey H; Lai, Chun-Yen; Mahakian, Lisa M; Larrat, Benoit; Dumont, Erik; Ferrara, Katherine W

2012-01-01

120

Pharmacokinetics of BPA in Gliomas with Ultrasound Induced Blood-Brain Barrier Disruption as Measured by Microdialysis  

PubMed Central

The blood-brain barrier (BBB) can be transiently disrupted by focused ultrasound (FUS) in the presence of microbubbles for targeted drug delivery. Previous studies have illustrated the pharmacokinetics of drug delivery across the BBB after sonication using indirect visualization techniques. In this study, we investigated the in vivo extracellular kinetics of boronophenylalanine-fructose (BPA-f) in glioma-bearing rats with FUS-induced BBB disruption by microdialysis. After simultaneous intravenous administration of BPA and FUS exposure, the boron concentration in the treated brains was quantified by inductively coupled plasma mass spectroscopy. With FUS, the mean peak concentration of BPA-f in the glioma dialysate was 3.6 times greater than without FUS, and the area under the concentration-time curve was 2.1 times greater. This study demonstrates that intracerebral microdialysis can be used to assess local BBB transport profiles of drugs in a sonicated site. Applying microdialysis to the study of metabolism and pharmacokinetics is useful for obtaining selective information within a specific brain site after FUS-induced BBB disruption.

Yang, Feng-Yi; Lin, Yi-Li; Chou, Fong-In; Lin, Yu-Chuan; Hsueh Liu, Yen-Wan; Chang, Lun-Wei; Hsieh, Yu-Ling

2014-01-01

121

Qualitative and Quantitative Analysis of Molecular Delivery Through the Ultrasound-Induced Blood-Brain Barrier Opening in Mice  

NASA Astrophysics Data System (ADS)

Recent studies have proven that focused ultrasound (FUS) in the presence of microbubbles can deliver large molecules across the blood-brain barrier (BBB) locally, transiently and non-invasively. In this study, the cellular effects, the size estimation of the opening and the amount delivered were inferred through qualitative and quantitative analysis of molecular delivery to the brain parenchyma in a murine model. The ultimate purpose was to build the foundation for future ultrasound-facilitated neurodegenerative disease treatment in humans. A bolus of microbubbles at 1 ?l/g body weight concentration was intravenously injected. Pulsed FUS was applied to the left hippocampus through the intact skin and skull followed by intravenously administration of fluorescence-conjugated dextran at 3 kDa, 10 kDa and 70 kDa. The brain were either sectioned for fluorescence imaging or homogenized for quantitative analysis. The concentration of 3 kDa, 10 kDa and 70 kDa dextrans delivered to the left brain hemisphere was quantified to be 7.9+/-4.9 ?g/g, 2.4+/-1.3 ?g/g and 0.9+/-0.47 ?g/g of brain weight. Smooth muscle cells engulfing the arterioles exhibited higher fluorescence in the case of 70 kDa dextran, compared to the 3 kDa dextran, demonstrating that fluorescence imaging can help with the understanding of the type of mechanism of molecular uptake by different brain cells.

Wang, Shougang; Baseri, Babak; Choi, James J.; Tung, Yao-Sheng; Morrison, Barclay; Konofagou, Elisa E.

2009-04-01

122

Capillary isoelectric focusing of microorganisms in the pH range 2-5 in a dynamically modified FS capillary with UV detection.  

PubMed

The isoelectric points of many microbial cells lie within the pH range spanning from 1.5 to 4.5. In this work, we suggest a CIEF method for the separation of cells according to their isoelectric points in the pH range of 2-5. It includes the segmental injection of the sample pulse composed of the segment of the selected simple ampholytes, the segment of the bioanalytes and the segment of carrier ampholytes into fused silica capillaries dynamically modified by poly(ethylene glycole). This polymer dissolved in the catholyte, in the anolyte and in the injected sample pulse was used for a prevention of the bioanalyte adsorption on the capillary surface and for the reduction of the electroosmotic flow. Between each focusing run, the capillaries were washed with the mixture of acetone/ethanol to achieve the reproducible and efficient CIEF. In order to trace of pH gradients, low-molecular-mass pI markers were used. The mixed cultures of microorganisms, Escherichia coli CCM 3954, Candida albicans CCM 8180, Candida parapsilosis, Candida krusei, Candida glabrata, Candida tropicalis, CCM 8223, Proteus vulgaris, Klebsiela pneumoniae, Staphylococcus aureus CCM 3953, Streptococcus agalactiae CCM 6187, Enterococcus faecalis CCM 4224 and Staphylococcus epidermidis CCM 4418, were focused and separated by the CIEF method suggested here. This CIEF method enables the separation and detection of the microbes from the mixed cultures within several minutes. The minimum detectable number of microbial cells was less than 10(3). PMID:16791563

Horká, Marie; R?zicka, Filip; Holá, Veronika; Slais, Karel

2006-07-01

123

Molecules of various pharmacologically-relevant sizes can cross the ultrasound-induced blood-brain barrier opening in vivo  

PubMed Central

Focused ultrasound (FUS) is hereby shown to noninvasively and selectively deliver compounds at pharmacologically relevant molecular weights through the opened blood-brain barrier (BBB). A complete examination on the size of the FUS-induced BBB opening, the spatial distribution of the delivered agents and its dependence on the agent's molecular weight were imaged and quantified using fluorescence microscopy. BBB opening in mice (n=13) was achieved in vivo after systemic administration of microbubbles and subsequent application of pulsed FUS (frequency: 1.525 MHz, peak-rarefactional pressure in situ: 569 kPa) to the left murine hippocampus through the intact skin and skull. BBB-impermeant, fluorescent-tagged dextrans at three distinct molecular weights spanning over several orders of magnitude were systemically administered and acted as model therapeutic compounds. First, dextrans of 3 and 70 kDa were delivered trans-BBB while 2000 kDa dextran was not. Second, compared to 70 kDa dextran, a higher concentration of 3 kDa dextran was delivered through the opened BBB. Third, the 3 and 70 kDa dextrans were both diffusely distributed throughout the targeted brain region. However, high concentrations of 70 kDa dextran appeared more punctated throughout the targeted region. In conclusion, FUS combined with microbubbles opened the BBB sufficiently to allow passage of compounds of at least 70 kDa, but not greater than 2000 kDa, into the brain parenchyma. This noninvasive and localized BBB opening technique could thus provide a unique means for the delivery of compounds of several magnitudes of kDa that include agents with shown therapeutic promise in vitro, but whose in vivo translation has been hampered by their associated BBB impermeability.

Choi, James J.; Wang, Shougang; Tung, Yao-Sheng; Morrison, Barclay; Konofagou, Elisa E.

2009-01-01

124

The Dependence of the Ultrasound-Induced Blood-Brain Barrier Opening Characteristics on Microbubble Size In Vivo  

NASA Astrophysics Data System (ADS)

Recent neuropharmaceutical developments have led to potent disease-modifying drugs. In spite of these advancements, most agents cannot traverse the blood-brain barrier (BBB) and deposit in the brain. Focused ultrasound (FUS) with microbubbles has been shown to induce noninvasive, localized, and transient BBB opening. Although promising, safety and efficacy concerns still remain. Previously reported experiments used conventional imaging contrast agents that have a wide size distribution. In this study, we hypothesize that BBB opening characteristics are dependent on bubble diameter. A 25 ?l bolus of in-house manufactured, lipid-shelled bubbles with either 1-2 or 4-5 ?m diameter ranges was injected intravenously. Pulsed FUS (frequency: 1.5 MHz, peak-negative pressure: 146-607 kPa, duty cycle: 20%, duration: 1-min) was then applied to the left hippocampus of mice (n = 16) in vivo through the intact skin and skull. MRI or fluorescence microscopy was used to determine BBB opening. Contrast-enhanced (Omniscan™ 0.75 mL; molecular weight: 574 Da) MRI (9.4-T) was acquired on multiple days after sonication to determine BBB opening and closing. Fluorescence microscopy was also used to determine the feasibility of delivering large, 3 kDa dextran compounds through the BBB. The BBB opening acoustic pressure threshold for the 4-5?m bubbles was in the 146-304 kPa range while the threshold for the 1-2?m bubbles was higher. In conclusion, FUS-induced BBB opening and closing was shown to be dependent on the bubble diameter indicating the possibility of specifically designing bubbles to enhance this therapeutic application.

Choi, James J.; Feshitan, Jameel A.; Wang, Shougang; Tung, Yao-Sheng; Baseri, Babak; Borden, Mark A.; Konofagou, Elisa E.

2009-04-01

125

Nested Polymerase Chain Reaction and Sequence- Based Detection of Leishmania Infection of Sand Flies in Recently Emerged Endemic Focus of Zoonotic Cutaneous Leishmaniasis, Southern Iran  

PubMed Central

Background: Geographical distribution of zoonotic cutaneous leishmaniasis (ZCL) has continuously been extended in recent years in Iran. The Beiza District is one of the newly-emerged endemic foci of ZCL in southern Iran. The main aim of the present study was to detect the vector(s) of ZCL in this area. Methods: To detect the fauna and vectors of ZCL in this district, sand flies were caught using sticky papers. Seventy randomly selected female sand flies out of 730 were molecularly investigated for Leishmania infection using species-specific nested polymerase chain reaction (PCR) assay between April and October 2010. Results: A total of 2543 sand flies were caught. The fauna was identified as 10 species (five Phlebotomus spp. and five Sergentomyia spp.). Phlebotomus papatasi was the most dominant species both indoors and outdoors (37.55% and 16.35 %, respectively). L. major was detected in 5 out of 48 investigated Phlebotomus papatasi (10.41%). Sequence-based characterization was carried out to confirm the PCR findings. The positive samples were shown to have 75-88% similarity with L. major sequences in GenBank. Conclusion: According to the findings of the present study, similar to the other foci of ZCL in Iran, P. papatasi is the proven and primary vector of CL. This study could be drawn upon for future strategy planning in this newly emerged endemic focus.

Azizi, Kourosh; Badzohreh, Abdollah; Sarkari, Bahador; Fakoorziba, Mohammad Reza; Kalantari, Mohsen; Moemenbellah-Fard, Mohammad Djaefar; Ali-Akbarpour, Mohsen

2013-01-01

126

Nested polymerase chain reaction and sequence- based detection of leishmania infection of sand flies in recently emerged endemic focus of zoonotic cutaneous leishmaniasis, southern iran.  

PubMed

Background: Geographical distribution of zoonotic cutaneous leishmaniasis (ZCL) has continuously been extended in recent years in Iran. The Beiza District is one of the newly-emerged endemic foci of ZCL in southern Iran. The main aim of the present study was to detect the vector(s) of ZCL in this area. Methods: To detect the fauna and vectors of ZCL in this district, sand flies were caught using sticky papers. Seventy randomly selected female sand flies out of 730 were molecularly investigated for Leishmania infection using species-specific nested polymerase chain reaction (PCR) assay between April and October 2010. Results: A total of 2543 sand flies were caught. The fauna was identified as 10 species (five Phlebotomus spp. and five Sergentomyia spp.). Phlebotomus papatasi was the most dominant species both indoors and outdoors (37.55% and 16.35 %, respectively). L. major was detected in 5 out of 48 investigated Phlebotomus papatasi (10.41%). Sequence-based characterization was carried out to confirm the PCR findings. The positive samples were shown to have 75-88% similarity with L. major sequences in GenBank. Conclusion: According to the findings of the present study, similar to the other foci of ZCL in Iran, P. papatasi is the proven and primary vector of CL. This study could be drawn upon for future strategy planning in this newly emerged endemic focus. PMID:24031105

Azizi, Kourosh; Badzohreh, Abdollah; Sarkari, Bahador; Fakoorziba, Mohammad Reza; Kalantari, Mohsen; Moemenbellah-Fard, Mohammad Djaefar; Ali-Akbarpour, Mohsen

2013-06-01

127

Reorganization of gap junctions after focused ultrasound blood-brain barrier opening in the rat brain  

PubMed Central

Ultrasound-induced opening of the blood–brain barrier (BBB) is an emerging technique for targeted drug delivery to the central nervous system. Gap junctions allow transfer of information between adjacent cells and are responsible for tissue homeostasis. We examined the effect of ultrasound-induced BBB opening on the structure of gap junctions in cortical neurons, expressing Connexin 36, and astrocytes, expressing Connexin 43, after focused 1-MHz ultrasound exposure at 1.25?MPa of one hemisphere together with intravenous microbubble (Optison, Oslo, Norway) application. Quantification of immunofluorescence signals revealed that, compared with noninsonicated hemispheres, small-sized Connexin 43 and 36 gap-junctional plaques were markedly reduced in areas with BBB breakdown after 3 to 6 hours (34.02±6.04% versus 66.49±2.16%, P=0.02 for Connexin 43; 33.80±1.24% versus 36.77±3.43%, P=0.07 for Connexin 36). Complementing this finding, we found significant increases in large-sized gap-junctional plaques (5.76±0.96% versus 1.02±0.84%, P=0.05 for Connexin 43; 5.62±0.22% versus 4.65±0.80%, P=0.02 for Connexin 36). This effect was reversible at 24 hours after ultrasound exposure. Western blot analyses did not show any change in the total connexin amount. These results indicate that ultrasound-induced BBB opening leads to a reorganization of gap-junctional plaques in both neurons and astrocytes. The plaque-size increase may be a cellular response to imbalances in extracellular homeostasis after BBB leakage.

Alonso, Angelika; Reinz, Eileen; Jenne, Jurgen W; Fatar, Marc; Schmidt-Glenewinkel, Hannah; Hennerici, Michael G; Meairs, Stephen

2010-01-01

128

In-line silica capillary tube all-silica fiber-optic Fabry-Perot interferometric sensor for detecting high intensity focused ultrasound fields.  

PubMed

Aiming at detecting high intensity focused ultrasound (HIFU) fields, this letter reports on a novel in-line silica capillary tube all-silica fiber-optic Fabry-Perot (ILSCT-ASFP) interferometric sensor fabricated by splicing a commercially available silica capillary tube to two single-mode fibers. The experimental results show that such a novel ILSCT-ASFP interferometric sensor with a cavity length of ?60.76 ?m has an excellent fringe visibility of up to ?20 dB, and the fringe visibility is still good when the cavity length extends up to ?1031.07 ?m. The measured wavelength-temperature sensitivity of 0.000858 nm/°C shows that the wavelength drift of the fabricated ILSCT-ASFP interferometric sensor towards temperature is extremely low. Meanwhile, the measurement of HIFU fields by this novel sensor is demonstrated, and the experimental results indicate that the signal-to-noise ratio of the sensing system for sensing a 0.93 MHz HIFU field with a pressure of 2.69 MPa in the focus area can reach 42.8 dB. The corresponding noise equivalent pressure is 0.0194 MPa, and the calculated acoustic sensitivity is 65.4 mV/MPa over a 2.5 MHz measurement bandwidth. PMID:22660116

Wang, D H; Wang, S J; Jia, P G

2012-06-01

129

Multispectral photoacoustic imaging of tissue denaturation induced by high-intensity focused ultrasound treatment  

NASA Astrophysics Data System (ADS)

This paper presents an ex vivo study in imaging high-intensity focused ultrasound induced tissue denaturation with multispectral photoacoustic approach. Beef tissues treated by both water bath and high-intensity focused ultrasound were imaged and evaluated by photoacoustic imaging method, where light in multiple optical wavelengths between 700nm and 900nm is applied. Tissue denaturation after being treated by water bath and high-intensity focused ultrasound has been observed in multispectral photoacoustic images. The denaturation is more striking in relatively shorter optical wavelength photoacoustic images than in relatively longer optical wavelength photoacoustic images. This study suggests that multispectral photoacoustic imaging method is promising in the evaluation of tissue denaturation induced by high- intensity focused ultrasound treatment.

Sun, Yao; Li, King C. P.; O'Neill, Brian

2013-03-01

130

Detection, identification and molecular typing of Leishmania major in Phlebotomus papatasi from a focus of zoonotic cutaneous leishmaniasis in central of Iran.  

PubMed

Leishmania major is the causative agent and Phlebotomus papatasi is the main vector of rural zoonotic cutaneous leishmaniasis (ZCL) in Iran and elsewhere. Nested PCR protocols were used to amplify a region of the ribosomal RNA amplicon of Leishmania (ITS1-5.8S rRNA gene) in female P. papatasi. In the current investigation, L. major was found in Natanz, Isfahan province in centre of Iran, in a focus of rural ZCL. Ten (1.8%) out of 549 female P. papatasi was found to be infected with L. major based on the PCR detection and sequencing of parasite ITS-rDNA. Nine (1.8%) out of 498 female P. papatasi infected with L. major came from animal shelters, inside houses and yards. And one (1.9%) out of 51 female P. papatasi infected with L. major came from gerbil borrows. Infection rates were higher for females containing red blood meals, large eggs (semi-mature and mature) than for those without either blood meals or eggs. From the 10 infections detected three different haplotypes of L. major were identified. Two haplotypes were found to be novel. The other haplotypes of L. major was found to be identical to that of isolates of L. major from Iran and in elsewhere using GenBank data. Comparisons of infection rates between habitats will be inaccurate when the proportions of blood-fed and gravid flies differ among sandfly samples. PMID:19854172

Parvizi, Parviz; Baghban, Nassrin; Novin, Elnaz Alaee; Absavaran, Azad

2010-02-01

131

Performance assessment of HIFU lesion detection by Harmonic Motion Imaging for Focused Ultrasound (HMIFU): A 3D finite-element-based framework with experimental validation  

PubMed Central

Harmonic Motion Imaging for Focused Ultrasound (HMIFU) is a novel high-intensity focused ultrasound (HIFU) therapy monitoring method with feasibilities demonstrated in vitro, ex vivo and in vivo. Its principle is based on Amplitude-modulated (AM) - Harmonic Motion Imaging (HMI), an oscillatory radiation force used for imaging the tissue mechanical response during thermal ablation. In this study, a theoretical framework of HMIFU is presented, comprising a customized nonlinear wave propagation model, a finite-element (FE) analysis module, and an image-formation model. The objective of this study is to develop such a framework in order to 1) assess the fundamental performance of HMIFU in detecting HIFU lesions based on the change in tissue apparent elasticity, i.e., the increasing Young's modulus, and the HIFU lesion size with respect to the HIFU exposure time and 2) validate the simulation findings ex vivo. The same HMI and HMIFU parameters as in the experimental studies were used, i.e., 4.5-MHz HIFU frequency and 25 Hz AM frequency. For a lesion-to-background Young's modulus ratio of 3, 6, and 9, the FE and estimated HMI displacement ratios were equal to 1.83, 3.69, 5.39 and 1.65, 3.19, 4.59, respectively. In experiments, the HMI displacement followed a similar increasing trend of 1.19, 1.28, and 1.78 at 10-s, 20-s, and 30-s HIFU exposure, respectively. In addition, moderate agreement in lesion size growth was also found in both simulations (16.2, 73.1 and 334.7 mm2) and experiments (26.2, 94.2 and 206.2 mm2). Therefore, the feasibility of HMIFU for HIFU lesion detection based on the underlying tissue elasticity changes was verified through the developed theoretical framework, i.e., validation of the fundamental performance of the HMIFU system for lesion detection, localization and quantification, was demonstrated both theoretically and ex vivo.

Hou, Gary Y.; Luo, Jianwen; Marquet, Fabrice; Maleke, Caroline; Vappou, Jonathan; Konofagou, Elisa E.

2014-01-01

132

Focused Screening and Treatment (FSAT): A PCR-Based Strategy to Detect Malaria Parasite Carriers and Contain Drug Resistant P. falciparum, Pailin, Cambodia  

PubMed Central

Recent studies have shown that Plasmodium falciparum malaria parasites in Pailin province, along the border between Thailand and Cambodia, have become resistant to artemisinin derivatives. To better define the epidemiology of P. falciparum populations and to assess the risk of the possible spread of these parasites outside Pailin, a new epidemiological tool named “Focused Screening and Treatment” (FSAT), based on active molecular detection of asymptomatic parasite carriers was introduced in 2010. Cross-sectional malariometric surveys using PCR were carried out in 20 out of 109 villages in Pailin province. Individuals detected as P. falciparum carriers were treated with atovaquone-proguanil combination plus a single dose of primaquine if the patient was non-G6PD deficient. Interviews were conducted to elicit history of cross-border travel that might contribute to the spread of artemisinin-resistant parasites. After directly observed treatment, patients were followed up and re-examined on day 7 and day 28. Among 6931 individuals screened, prevalence of P. falciparum carriers was less than 1%, of whom 96% were asymptomatic. Only 1.6% of the individuals had a travel history or plans to go outside Cambodia, with none of those tested being positive for P. falciparum. Retrospective analysis, using 2010 routine surveillance data, showed significant differences in the prevalence of asymptomatic carriers discovered by FSAT between villages classified as “high risk” and “low risk” based on malaria incidence data. All positive individuals treated and followed-up until day 28 were cured. No mutant-type allele related to atovaquone resistance was found. FSAT is a potentially useful tool to detect, treat and track clusters of asymptomatic carriers of P. falciparum along with providing valuable epidemiological information regarding cross-border movements of potential malaria parasite carriers and parasite gene flow.

Hoyer, Stefan; Nguon, Sokomar; Kim, Saorin; Habib, Najibullah; Khim, Nimol; Sum, Sarorn; Christophel, Eva-Maria; Bjorge, Steven; Thomson, Andrew; Kheng, Sim; Chea, Nguon; Yok, Sovann; Top, Samphornarann; Ros, Seyha; Sophal, Uth; Thompson, Michelle M.; Mellor, Steve; Ariey, Frederic; Witkowski, Benoit; Yeang, Chhiang; Yeung, Shunmay; Duong, Socheat; Newman, Robert D.; Menard, Didier

2012-01-01

133

A highly sensitive method for quantification of myosin light chain phosphorylation by capillary isoelectric focusing with laser-induced fluorescence detection.  

PubMed

Activation of myosin II by phosphorylation of the 20 kDa regulatory light chains (LC20) has been implicated in numerous contractile and motile events, e.g., smooth muscle contraction, cytokinesis, and cell migration. The ability to analyze LC20 phosphorylation in minute samples is critical to determine the importance of LC20 phosphorylation in diverse physiological processes. We have developed a method for the separation and quantification of unphosphorylated, monophosphorylated, and diphosphorylated LC20 with a detection limit of 1 pg (50 amol). LC20 is initially isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transblotted to a polyvinlyidene difluoride (PVDF) membrane. The region of the membrane containing the LC20 band (identified by electrophoresis of purified LC20 in a neighboring lane) is cut out and fluorescently labeled with Alexa Fluor 488 C5 maleimide. The labeled LC20 is eluted from the membrane with detergent and subjected to capillary isoelectric focusing (CIEF) to separate unphosphorylated, mono-, and diphosphorylated LC20, which are detected and quantified by laser-induced fluorescence (LIF). A linear relationship between log(peak area) and log(LC20 amount) is observed over the range of 50 amol-150 fmol. Quantification of LC20 phosphorylation by CIEF with LIF detection was compared with three commonly used methods with much lower levels of sensitivity: urea/glycerol-PAGE with Western blotting, phosphorylation by [gamma-32P]ATP with Cerenkov counting, and phosphorylation by [gamma-32P]ATP followed by SDS-PAGE, autoradiography, and scanning densitometry. All four methods gave very similar quantitative results, the major difference being that the new method exhibits 3000-fold enhanced sensitivity. This method is therefore applicable to quantitative analysis of phosphorylation of minute quantities of LC20. PMID:15690429

Shiraishi, Mitsuya; Loutzenhiser, Rodger D; Walsh, Michael P

2005-02-01

134

Investigations into ultrasound induced atomization.  

PubMed

The present work deals with measurements of the droplet size distribution in an ultrasonic atomizer using photographic analysis with an objective of understanding the effect of different equipment parameters such as the operating frequency, power dissipation and the operating parameters such as the flow rate and liquid properties on the droplet size distribution. Mechanistic details about the atomization phenomena have also been established using photographic analysis based on the capture of the growth of the instability and sudden ejection of droplets with high velocity. Velocity of these droplets has been measured by capturing the motion of droplets as streaks. It has been observed that the droplet size decreases with an increase in the frequency of atomizer. Droplet size distribution was found to change from the narrow to wider range with an increase in the intensity of ultrasound. The drop size was found to decrease with an increase in the fluid viscosity. The current work has clearly highlighted the approach for the selection of operating parameters for achieving a desired droplet size distribution using ultrasonic atomization and has also established the controlling mechanisms for the formation of droplet. An empirical correlation for the prediction of the droplet size has been developed based on the liquid and equipment operating properties. PMID:22672979

Ramisetty, Kiran A; Pandit, Aniruddha B; Gogate, Parag R

2013-01-01

135

Particle focusing in microfluidic devices  

Microsoft Academic Search

Focusing particles (both biological and synthetic) into a tight stream is usually a necessary step prior to counting, detecting,\\u000a and sorting them. The various particle focusing approaches in microfluidic devices may be conveniently classified as sheath\\u000a flow focusing and sheathless focusing. Sheath flow focusers use one or more sheath fluids to pinch the particle suspension\\u000a and thus focus the suspended

Xiangchun Xuan; Junjie Zhu; Christopher Church

2010-01-01

136

Molecular detection and identification of Leishmania infection in naturally infected sand flies in a focus of cutaneous leishmaniasis in northern Morocco  

PubMed Central

Background Cutaneous leishmaniasis is an infectious disease caused by various species of the flagellate protozoan Leishmania. During the past 20 years, cutaneous leishmaniasis has emerged as a major public health threat in Morocco. The main objective of this study was to study the occurrence of Leishmania infection in vectors and to identify sand fly blood meal sources in an endemic locality of cutaneous leishmaniasis within Sefrou province, where the vectors of leishmaniasis were still unknown. Methods 2650 sand flies were collected using CDC miniature light traps and identified morphologically. The identified sand flies were tested for Leishmania infection by nested PCR. The source of blood meal of 10 freshly engorged females: 6 Phlebotomus longicuspis and 4 Phlebotomus sergenti, was determined using the Cyt b sequence. Results The collected sand flies consisted of 10 species, seven of which belonged to the genus Phlebotomus and three to the genus Sergentomyia. The most abundant species was P. longicuspis, accounting for 72% of the total sand flies collected. In females of three P. longicuspis and four P. sergenti, Leishmania infantum and Leishmania tropica DNA was detected, respectively. The source of blood meal of engorged females showed that all sand flies tested fed on humans. Conclusions We report for the first time the natural infection of P. longicuspis with L. infantum in Morocco. The high frequency of this species in this region, in addition to its anthropophilic character make P. longicuspis the putative vector of L. infantum in this cutaneous leishmaniasis focus where L. tropica is confirmed as the causative agent of the disease and P. sergenti as its vector. The presence of L. infantum, and its presumed vector in this area, makes this a site of high risk of visceral leishmaniasis, mostly because of the proximity of a focus of human and canine visceral leishmaniasis.

2014-01-01

137

Detection and molecular typing of Leishmania tropica from Phlebotomus sergenti and lesions of cutaneous leishmaniasis in an emerging focus of Morocco  

PubMed Central

Background Cutaneous leishmaniasis is an infectious disease caused by flagellate protozoa of the genus Leishmania. In Morocco, anthroponotic cutaneous leishmaniasis due to Leishmania tropica is considered as a public health problem, but its epidemiology has not been fully elucidated. The main objective of this study was to detect Leishmania infection in the vector, Phlebotomus sergenti and in human skin samples, in the El Hanchane locality, an emerging focus of cutaneous leishmaniasis in central Morocco. Methods A total of 643 sand flies were collected using CDC miniature light traps and identified morphologically. Leishmania species were characterized by ITS1 PCR-RFLP and ITS1-5.8S rRNA gene nested-PCR of samples from 123 females of Phlebotomus sergenti and 7 cutaneous leishmaniasis patients. Results The sand flies collected consisted of 9 species, 7 of which belonged to the genus Phlebotomus and two to the genus Sergentomyia. Phlebotomus sergenti was the most predominant (76.67%). By ITS1 PCR-RFLP Leishmania tropica was found in three Phlebotomus sergenti females and four patients (4/7). Using nested PCR Leishmania tropica was identified in the same three Phlebotomus sergenti females and all the 7 patients. The sequencing of the nested PCR products recognized 7 haplotypes, of which 6 have never been described. Conclusions This is the first molecular detection and identification of Leishmania tropica in human skin samples and Phlebotomus sergenti in support of its vector status in El Hanchane. The finding of seven Leishmania tropica haplotypes underscores heterogeneity of this species at a high level in Morocco.

2013-01-01

138

Detection of metalloproteins in human liver cytosol by synchrotron radiation X-ray fluorescence combined with gel filtration chromatography and isoelectric focusing separation.  

PubMed

Synchrotron radiation X-ray fluorescence (SRXRF) spectroscopy is an advanced method of quantitative multielemental analysis with space resolution of several microm and sensitivities in the microg g(-1) range. It can be used for keeping track of trace elements after an electrophoretic separation of biological samples. In this paper, proteins in human liver cytosol were separated with gel filtration chromatography and thin layer isoelectric focusing (IEF). The contents of metal ions in protein bands were determined by SRXRF. The results showed that in the molecular weight (MW) range of 10 approximately 25 kDa, there were at least 2 Zn-containing bands with isoelectric point (pI) of 5 approximately 6 and 6.2 approximately 7, respectively and about 11 Fe-containing proteins with pI of 4.4, 4.6, 4.8, 5.0, 5.2, 5.3, 5.5, 5.6, 6.6, 6.8, and 7.2, respectively, present in human liver cytosol. The Zn-containing band with pI of 5-6 is the dominant species of zinc in this MW range. In addition, the Cu-containing bands with pI of 5.0 and below 4.8 were also detected. It is demonstrated that the procedure could be widely used in further investigations of the chemical species of trace elements in biological samples. PMID:12537382

Gao, Yuxi; Chen, Chunying; Chai, Zhifang; Zhao, Jiujiang; Liu, Jing; Zhang, Peiqun; Heb, a Wei; Huang, Yuying

2002-12-01

139

Adiabatic Focuser  

SciTech Connect

Theoretical analysis is made of an intense relativistic electron beam. such as would be available from a linear collider, moving through a plasma of increasing density, but density always less than that of the beam (underdense). In this situation. the plasma electrons are expelled from the beam channel and the electrons are subject to an ever-increasing focusing force provided by the channel ions. Analysis is made on the beam radiation energy loss in the classical, the transition, and the quantum regimes. It is shown that the focuser is insensitive to the beam energy spread due to radiation loss. Furthermore, because of the different scaling behaviors in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded. The sensitivity of the system to the optic mismatch and the nonlinearity is also analyzed. Examples are given with SLC-type and TLC-type parameters.

Chen, P.; Oide, K.; Sessler, Andrew M.; Yu, S.S.

1989-08-01

140

Integration of dialysis membranes into a poly(dimethylsiloxane) microfluidic chip for isoelectric focusing of proteins using whole-channel imaging detection.  

PubMed

A poly(dimethylsiloxane) microfluidic chip-based cartridge is developed and reported here for protein analysis using isoelectic focusing (IEF)-whole-channel imaging detection (WCID) technology. In this design, commercial dialysis membranes are integrated to separate electrolytes and samples and to reduce undesired pressure-driven flow. Fused-silica capillaries are also incorporated in this design for sample injection and channel surface preconditioning. This structure is equivalent to that of a commercial fused-silica capillary-based cartridge for adapting to an IEF analyzer (iCE280 analyzer) to perform IEF-WCID. The successful integration of dialysis membranes into a microfluidic chip significantly improves IEF repeatability by eliminating undesired pressure-driven hydrodynamics and also makes sample injection much easier than that using the first-generation chip as reported recently. In this study, two microfluidic chips with a 100-microm-high, 100-microm-wide and a 200-microm-high, 50-microm-wide microchannel, respectively, were applied for qualitative and quantitative analysis of proteins. The mixture containing six pI markers with a pH range of 3-10 was successfully separated using IEF-WCID. The pH gradient exhibited a good linearity by plotting the pI value versus peak position, and the correlation coefficient reached 0.9994 and 0.9995 separately for the two chips. The separation of more complicated human hemoglobin control sample containing HbA, HbF, HbS, and HbC was also achieved. Additionally, for the quantitative analysis, a good linearity of IEF peak value versus myoglobin concentration in the range of 20-100 microg/mL was obtained. PMID:18754670

Ou, Junjie; Glawdel, Tomasz; Samy, Razim; Wang, Shuwen; Liu, Zhen; Ren, Carolyn L; Pawliszyn, Janusz

2008-10-01

141

Metal distribution patterns in the mussel Mytilus edulis cytosols using size-exclusion chromatography and double focusing ICP-MS detection.  

PubMed

In order to estimate metal distribution patterns in biomolecules of different sizes and their possible relationship with environmental heavy metal contamination, multi-elemental distributions in different fractions of the cytosols of mussels were studied. To do so, samples were collected from natural populations of two coastal regions in Spain: a wild (uncontaminated) coast and an industrialised (contaminated) area in Asturias. Moreover, some commercial mussels from the Galicia coast were also investigated for comparison. Aliquots of the mussel cytosol extracts from each sample were applied to a calibrated Sephadex G-75 column (100 x 1 cm) and forty 3 ml fractions were obtained. After suitable dilution, 18 trace metals were determined by double focusing inductively coupled plasma mass spectrometry (DF-ICP-MS). The use of DF-ICP-MS detection allowed the resolution of several spectral interferences that cannot be resolved by quadrupole ICP-MS. Accurate results for ultratrace elements at basal levels are possible even after sample dilution to prevent matrix effects. After biomolecule-metal association pattern has been established, quantitative analysis of mussel cytosols from the three coastal areas was carried out, using external aqueous calibration plus standard additions to correct for possible matrix effects. Results showed that total metal contents increased following the expected order: wild coast < Galicia coast < industrial area coast. Speciation of Cu, Zn, Ca, U, Ni, Mo, Mn, Cr, V, Cd, Al and Sb showed a similar distribution pattern among cytosolic ligands for all the studied samples. Conversely, Fe, Pb, Sn, Co, Hg and Ag were found to exhibit different speciation patterns when samples from industrialised (contaminated) and non-industrialised areas were compared. PMID:11219056

Ferrarello, C N; Fernández de la Campa, M R; Sariego Muñiz, C; Sanz-Medel, A

2000-12-01

142

Electrophoretic Focusing  

NASA Technical Reports Server (NTRS)

Electrophoretic focusing is a new method of continuous flow electrophoresis that introduces precision flow control to achieve high resolution separations. The electric field is applied perpendicular to an incoming sample lamina and buffer but also perpendicular to the broad faces of the thin rectangular chamber. A uniform fluid cross-flow then enters and exits the separation chamber through the same broad faces which are porous. A balance is achieved by adjusting either the electric field or the cross-flow so the desired sample fraction with its specific migration velocity encounters an opposing flow of the same velocity. Applying an electric field transverse to the incoming sample lamina and opposing this field with a carefully configured buffer flow, a sample constituent can be selected and focused into a narrow stream for subsequent analysis. Monotonically changing either electric field or buffer cross-flow will yield a scan of all constituents of the sample. Stopping the scan increases the collection time for minor constituents to improve their analysis. Using the high voltage gradients and/or cross-flow to rapidly deflect extraneous sample through the porous screens and into either of the side (purge) chambers, the selected sample is focused in the center plane of the separation chamber and collected without contact or interaction with the separation chamber walls. Results will be presented on the separation of a range of materials including dyes, proteins, and monodisperse polystyrene latexes. Sources of sample dispersion inherent in other electrokinetic techniques will be shown to be negligible for a variety of sample concentrations, buffer properties and operating conditions.

Snyder, Robert S.

2001-01-01

143

Theoretical and experimental study on temperature elevation behind ribs caused by weakly focused ultrasound  

PubMed Central

Temperature distribution in tissues behind ribs produced by weakly focused ultrasound had been calculated using Pennes bioheat equation, and the validity of the theoretical model was experimentally confirmed in vitro using porcine live. We found that the position of the maximum temperature in tissue is strongly influenced by the distance between the transducer and ribs, while the gap between ribs is the determining factor for the maximum achievable temperature. Within the focal length, when the distance between the transducer and ribs increases, the maximum temperature increases and its position shifts away from the transducer. The rib width has little effect on the position of the maximum temperature but affects the achievable peak temperature. Our results provide useful information for treating liver cancers using ultrasound induced hyperthermia.

Liu, Xiaozhou; Yin, Chang; Gong, Xiufen; Cao, Wenwu

2010-01-01

144

On-line focusing of 5-hydroxy-tryptamine type 3 receptor antagonists via the combination of field-enhanced sample injection and dynamic pH junction in capillary electrophoresis with amperometric detection.  

PubMed

In the present work, an on-line dual focusing technique based on field-enhance sample injection (FASI) and dynamic pH junction (DypH) was developed for the analysis of two 5-hydroxy-tryptamine type 3 receptor (5-HT3) antagonists ondansetron (Ond) and tropisetron (Tro) by capillary electrophoresis with amperometric detection (CE-AD) system. By preparing the sample in a lower conductivity (FASI condition) and lower pH value (DypH condition) matrix relative to the background electrolyte (BGE) solution, a simple and effective dual focusing approach, FASI-DypH was achieved. In this stacking mode, a large amount of analytes could be electrokinetically injected into the capillary and stacked at the boundary of the sample and the BGE zone as a result of deprotonation and decrease in the electric field. Effects of separation, detection and FASI-DypH focusing conditions were investigated in detail. Under the optimum conditions, good separation for Ond and Tro was achieved within 8min. In comparison with the conventional CE-AD analysis method, the present dual focusing technique enabled the enhancement factors in terms of peak heights to reach 357-fold and 345-fold for Ond and Tro, respectively. The limits of detection (LODs) (S/N=3) for Ond and Tro were 2nM and 5nM, respectively. The intraday and interday repeatabilities (RSDs) were less than 4.5% and 2.9% for peak height and migration time, respectively. The proposed method was successfully applied for the analysis of Ond and Tro in human urine sample. PMID:24461640

Li, Libo; Xu, Lei; Huang, Jianshe; You, Tianyan

2014-02-28

145

A dense plasma focus-based neutron source for a single-shot detection of illicit materials and explosives by a nanosecond neutron pulse  

NASA Astrophysics Data System (ADS)

Recent progress in a single-pulse Nanosecond Impulse Neutron Investigation System (NINIS) intended for interrogation of hidden objects by means of measuring elastically scattered neutrons is presented in this paper. The method uses very bright neutron pulses having duration of the order of 10 ns only, which are generated by dense plasma focus (DPF) devices filled with pure deuterium or DT mixture as a working gas. The small size occupied by the neutron bunch in space, number of neutrons per pulse and mono-chromaticity (?E/E~1%) of the neutron spectrum provides the opportunity to use a time-of-flight (TOF) technique with flying bases of about a few metres. In our researches we used DPF devices having bank energy in the range 2-7 kJ. The devices generate a neutron yield of the level of 108-109 2.45 MeV and 1010-1011 14 MeV neutrons per pulse with pulse duration ~10-20 ns. TOF base in the tests was 2.2-18.5 m. We have demonstrated the possibility of registering of neutrons scattered by the substances under investigation—1 litre bottles with methanol (CH3OH), phosphoric (H2PO4) and nitric (HNO3) acids as well as a long object—a 1 m gas tank filled with deuterium at high pressure. It is shown that the above mentioned short TOF bases and relatively low neutron yields are enough to distinguish different elements' nuclei composing the substance under interrogation and to characterize the geometry of lengthy objects in some cases. The wavelet technique was employed to 'clean' the experimental data registered. The advantages and restrictions of the proposed and tested NINIS technique in comparison with other methods are discussed.

Gribkov, V. A.; Latyshev, S. V.; Miklaszewski, R. A.; Chernyshova, M.; Drozdowicz, K.; Wi?cek, U.; Tomaszewski, K.; Lemeshko, B. D.

2010-03-01

146

Simultaneous Measurement of Thermophysical Properties of Tissue-Mimicking Phantoms for High Intensity Focused Ultrasound (HIFU) Exposures  

NASA Astrophysics Data System (ADS)

Tissue-mimicking phantoms, including bovine serum albumin phantoms and egg white phantoms, have been developed for, and in laboratory use for, real-time visualization of high intensity focused ultrasound-induced thermal coagulative necrosis since 2001. However, until now, very few data are available concerning their thermophysical properties. In this article, a step-wise transient plane source method has been used to determine the values of thermal conductivity, thermal diffusivity, and specific heat capacity of egg white phantoms with elevated egg white concentrations (0 v/v% to 40 v/v%, by 10 v/v% interval) at room temperature (~20 °C). The measured thermophysical properties were close to previously reported values; the thermal conductivity and thermal diffusivity were linearly proportional to the egg white concentration within the investigation range, while the specific heat capacity decreased as the egg white concentration increased. Taking account of large differences between real experiment and ideal model, data variations within 20 % were accepted.

Gao, Jing; You, Jiang; Huang, Zhihong; Cochran, Sandy; Corner, George

2012-03-01

147

Comprehensive two-dimensional separation system by coupling capillary reverse-phase liquid chromatography to capillary isoelectric focusing for peptide and protein mapping with laser-induced fluorescence detection.  

PubMed

A comprehensive two-dimensional (2-D) separation system, coupling capillary reverse-phase liquid chromatography (cRPLC) to capillary isoelectric focusing (CIEF), is described for protein and peptide mapping. cRPLC, the first dimension, provided high-resolution separations for salt-free proteins. CIEF, the second dimension with an orthogonal mechanism to cRPLC afforded excellent resolution capability for proteins with efficient protein enrichment. Since all sample fractions in cRPLC effluents could be transferred to the CIEF dimensions, the combination of the two high-efficiency separations resulted in maximal separation capabilities of each dimension. Separation effectiveness of this approach was demonstrated using complex protein/peptide samples, such as yeast cytosol and a BSA tryptic digest. A peak capacity of more than 10 000 had been achieved. A laser-induced fluorescence (LIF) detector, developed for this system, allowed for high-sensitive detection, with a fmol level of peptide detection for the BSA digest. FITC and BODIPY maleimide were used to tag the proteins, and the latter was found better both for separation and detection in our 2-D system. PMID:14518059

Mao, Yu; Zhang, Xiangmin

2003-09-01

148

Method of focusing optical apparatus  

SciTech Connect

Automatic focusing apparatus comprising a beam focusing assembly disposed for directing through an axially spaced focal spot a scanning light beam having a periodic translational movement characterized by a first fundamental frequency component, a focus evaluating assembly disposed for detecting adjacent the focal spot a periodic translational movement of the focused beam characterized by a fundamental frequency component which is compared with said first fundamental frequency component to determine the relative phase relationship, and a target positioning assembly disposed for automatically positioning a selected surface of a target at the focal spot in accordance with the periodic translational movement of the focused beam and said determination of relative phase relationship. This automatic focusing apparatus may be embodied in a laser material removal system having a laser source connected to the focus evaluating assembly for automatic activation when the selected surface of a target is positioned at the focal spot to direct a light beam of suitably high energy onto the selected surface for removing material therefrom.

Luck Jr., C. F.

1985-02-26

149

Reciprocal focus profile.  

PubMed

A focus profile having a steeper peak is more resistant to image noise in the autofocus (AF) process of a digital camera. However, a focus profile of such shape normally has a flatter out-of-focus region on either side of the profile, resulting in a slow AF process due to the lack of clue about where the lens should move when the lens is in such regions. To address the problem, we provide a statistical analysis of the focus profile and show that a strictly monotonic transformation of the focus profile preserves the accuracy of the AF. On the basis of this analysis, we propose a new focus profile representation that transforms the focus profile to the reciprocal domain in which the reciprocal focus profile is modeled by a polynomial function. This transformation makes the AF mathematically tractable and boosts the search speed. Experimental results are shown to demonstrate the advantage of the proposed representation. PMID:21843991

Tsai, Dong-Chen; Chen, Homer H

2012-02-01

150

In Focus Online  

MedlinePLUS

... P rofessionals & Researchers Funded Grants Applications and Forms Foundation Written Articles Clinical Trials Eye Conditions Resources R ... Releases In Focus in focus Online Multimedia Conferences Foundation News J oin the Fight Donate Other Ways ...

151

Acoustic characterization of high intensity focused ultrasound fields: a combined measurement and modeling approach.  

PubMed

Acoustic characterization of high intensity focused ultrasound (HIFU) fields is important both for the accurate prediction of ultrasound induced bioeffects in tissues and for the development of regulatory standards for clinical HIFU devices. In this paper, a method to determine HIFU field parameters at and around the focus is proposed. Nonlinear pressure waveforms were measured and modeled in water and in a tissue-mimicking gel phantom for a 2 MHz transducer with an aperture and focal length of 4.4 cm. Measurements were performed with a fiber optic probe hydrophone at intensity levels up to 24,000 W/cm(2). The inputs to a Khokhlov-Zabolotskaya-Kuznetsov-type numerical model were determined based on experimental low amplitude beam plots. Strongly asymmetric waveforms with peak positive pressures up to 80 MPa and peak negative pressures up to 15 MPa were obtained both numerically and experimentally. Numerical simulations and experimental measurements agreed well; however, when steep shocks were present in the waveform at focal intensity levels higher than 6000 W/cm(2), lower values of the peak positive pressure were observed in the measured waveforms. This underrepresentation was attributed mainly to the limited hydrophone bandwidth of 100 MHz. It is shown that a combination of measurements and modeling is necessary to enable accurate characterization of HIFU fields. PMID:19062878

Canney, Michael S; Bailey, Michael R; Crum, Lawrence A; Khokhlova, Vera A; Sapozhnikov, Oleg A

2008-10-01

152

Acoustic characterization of high intensity focused ultrasound fields: A combined measurement and modeling approach  

PubMed Central

Acoustic characterization of high intensity focused ultrasound (HIFU) fields is important both for the accurate prediction of ultrasound induced bioeffects in tissues and for the development of regulatory standards for clinical HIFU devices. In this paper, a method to determine HIFU field parameters at and around the focus is proposed. Nonlinear pressure waveforms were measured and modeled in water and in a tissue-mimicking gel phantom for a 2 MHz transducer with an aperture and focal length of 4.4 cm. Measurements were performed with a fiber optic probe hydrophone at intensity levels up to 24 000 W?cm2. The inputs to a Khokhlov–Zabolotskaya–Kuznetsov-type numerical model were determined based on experimental low amplitude beam plots. Strongly asymmetric waveforms with peak positive pressures up to 80 MPa and peak negative pressures up to 15 MPa were obtained both numerically and experimentally. Numerical simulations and experimental measurements agreed well; however, when steep shocks were present in the waveform at focal intensity levels higher than 6000 W?cm2, lower values of the peak positive pressure were observed in the measured waveforms. This underrepresentation was attributed mainly to the limited hydrophone bandwidth of 100 MHz. It is shown that a combination of measurements and modeling is necessary to enable accurate characterization of HIFU fields.

Canney, Michael S.; Bailey, Michael R.; Crum, Lawrence A.; Khokhlova, Vera A.; Sapozhnikov, Oleg A.

2008-01-01

153

Plasma Focus Breeder.  

National Technical Information Service (NTIS)

High voltage generation on pinched plasma by a plasma focus device was investigated. Fissile fuels are bred with the help of high current plasma focus device. A mechanism of accelerating proton beam in plasma focus device to high energy changes the induct...

K. Ikuta

1981-01-01

154

Plasma focus devices  

Microsoft Academic Search

The paper examines the principle of operation and the characteristic plasma properties (dimensions of the plasma focus, density, lifetime and macroscopic instability, electric and magnetic fields, electron temperature, turbulence, electron beams, and X-ray emission, ion temperature, ion distribution function, neutron emission) of plasma focus devices. The plasma focus is considered as a source of neutrons, energy, light and X-rays, and

G. Decker; R. Wienecke

1976-01-01

155

Alternating phase focused linacs  

DOEpatents

A heavy particle linear accelerator employing rf fields for transverse and ongitudinal focusing as well as acceleration. Drift tube length and gap positions in a standing wave drift tube loaded structure are arranged so that particles are subject to acceleration and succession of focusing and defocusing forces which contain the beam without additional magnetic or electric focusing fields.

Swenson, Donald A. (Los Alamos, NM)

1980-01-01

156

Plasma Focus Breeder.  

National Technical Information Service (NTIS)

Instead of using linear accelerators, it is possible to breed fissile fuels with the help of high current plasma focus device. A mechanism of accelerating proton beam in plasma focus device to high energy would be a change of inductance in plasma column b...

K. Ikuta

1981-01-01

157

Microfabricated particle focusing device  

DOEpatents

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.

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

158

Focus, 2000-2001.  

ERIC Educational Resources Information Center

These three issues of 2000-2001 "Focus" present a collection of papers focusing on issues related to poverty. The first issue discusses child support enforcement policy and low-income families, highlighting such issues as fragile families and child wellbeing; low-income families and the child support enforcement system; child support enforcement…

Focus, 2001

2001-01-01

159

Agreement, Shells, and Focus.  

ERIC Educational Resources Information Center

Reconsiders development and licensing of agreement as a syntactic projection and argues for a productive developmental relation between agreement and the category of focus. Suggests that focus projections are initially selected by a variety of functional heads with real semantic content, then, over time decays into a simple concord shell. Upon…

Simpson, Andrew; Wu, Zoe

2002-01-01

160

inFocus  

NSDL National Science Digital Library

The inFocus feature is quite useful if you want to focus in on a particular feature of a website. Visitors can just type in any given website, and they will have the ability to create rectangles that highlight certain areas of interest. It's very easy to utilize and it is compatible with all operating systems.

2012-06-22

161

OECD Focus Hot File  

NSDL National Science Digital Library

In each issue of the Organization for Economic Co-operation and Development (OECD)'s Focus Hot File, recent books and government reports of interest are listed with summaries and contact information. Past listings may be browsed by country in the Focus Compendium, and related publications are hyperlinked throughout.

162

BringFocus  

NSDL National Science Digital Library

Everyone knows that it is easy to go down the proverbial rabbit hole while working online. One minute you could be checking on some higher education statistics and you might end up at IMDB.com for a solid hour. BringFocus helps users stay on task by helping them stay focused on one task at a time. Visitors can view screenshots of the program and also view a short demonstration video for more information on how BringFocus works. This version is compatible with Windows operating systems.

2012-02-17

163

MetroFocus  

NSDL National Science Digital Library

Metro Focus is a multi-platform news magazine focusing on the New York region. The program includes commentary on current events, in-depth reporting, and news updates on areas such as education, transportation, and poverty. Visitors can look around at the organization's programs via the Topics tab at the top of the page and also just scroll through recent episodes which cover everything from the history of Brooklyn, the state of affordable health care in New York, and solutions to assist the chronically homeless. The Watch MetroFocus area affords access to hundreds of complete episodes.

164

Subsurface contaminants focus area.  

National Technical Information Service (NTIS)

The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, includi...

1996-01-01

165

Focusing corner cube  

DOEpatents

This invention retortreflects and focuses a beam of light. The invention comprises a modified corner cube reflector wherein one reflective surface is planar, a second reflective surface is spherical, and the third reflective surface may be planar or convex cylindrical.

Monjes, J.A.

1985-09-12

166

Inertial focusing in microfluidics.  

PubMed

When Segré and Silberberg in 1961 witnessed particles in a laminar pipe flow congregating at an annulus in the pipe, scientists were perplexed and spent decades learning why such behavior occurred, finally understanding that it was caused by previously unknown forces on particles in an inertial flow. The advent of microfluidics opened a new realm of possibilities for inertial focusing in the processing of biological fluids and cellular suspensions and created a field that is now rapidly expanding. Over the past five years, inertial focusing has enabled high-throughput, simple, and precise manipulation of bodily fluids for a myriad of applications in point-of-care and clinical diagnostics. This review describes the theoretical developments that have made the field of inertial focusing what it is today and presents the key applications that will make inertial focusing a mainstream technology in the future. PMID:24905880

Martel, Joseph M; Toner, Mehmet

2014-07-11

167

Focus on Varicose Veins  

MedlinePLUS

What are varicose veins? Varicose veins are the visible and large, bulging, surface veins, felt under the skin. They generally are larger ... and treatment Focus on Varicose Veins How are varicose veins diagnosed? The diagnosis of varicose veins is made ...

168

Final focus nomenclature  

SciTech Connect

The formal names and common names for all devices in the final focus system of the SLC are listed. The formal names consist of a device type designator, microprocessor designator, and a four-digit unit number. (LEW)

Erickson, R.

1986-08-08

169

Planar-focusing cathodes.  

SciTech Connect

Conventional {pi}-mode rf photoinjectors typically use magnetic solenoids for emittance compensation. This provides independent focusing strength but can complicate rf power feed placement, introduce asymmetries (due to coil crossovers), and greatly increase the cost of the photoinjector. Cathode-region focusing can also provide for a form of emittance compensation. Typically this method strongly couples focusing strength to the field gradient on the cathode, however, and usually requires altering the longitudinal position of the cathode to change the focusing. We propose a new method for achieving cathode-region variable-strength focusing for emittance compensation. The new method reduces the coupling to the gradient on the cathode and does not require a change in the longitudinal position of the cathode. Expected performance for an S-band system is similar to conventional solenoid-based designs. This paper presents the results of rf cavity and beam dynamics simulations of the new design. We have proposed a method for performing emittance compensation using a cathode-region focusing scheme. This technique allows the focusing strength to be adjusted somewhat independently of the on-axis field strength. Beam dynamics calculations indicate performance should be comparable to presently in-use emittance compensation schemes, with a simpler configuration and fewer possibilities for emittance degradation due to the focusing optics. There are several potential difficulties with this approach, including cathode material selection, cathode heating, and peak fields in the gun. We hope to begin experimenting with a cathode of this type in the near future, and several possibilities exist for reducing the peak gradients to more acceptable levels.

Lewellen, J. W.; Noonan, J.; Accelerator Systems Division (APS)

2005-01-01

170

Neutron focusing using converging guides  

NASA Astrophysics Data System (ADS)

The neutron current density can be increased by using a converging guide; this can be particularly useful as the last section of a long straight guide. We give the expected flux gains for such a system. This increased density is obtained at the expense of increased divergence of the beam, which is unimportant in neutron absorption techniques, such as prompt gamma activation analysis and neutron depth profiling. These experiments can benefit from improved detection limits available when the neutron beam is focused by a neutron optical element such as a converging guide.

Mildner, D. F. R.

1991-10-01

171

EDITORIAL: Focus on Plasmonics FOCUS ON PLASMONICS  

NASA Astrophysics Data System (ADS)

Plasmonics is an emerging field in optics dealing with the so-called surface plasmons whose extraordinary properties are being both analyzed from a fundamental point of view and exploited for numerous technological applications. Surface plasmons associated with surface electron density oscillations decorating metal dielectric interfaces were discovered by Rufus Ritchie in the 1950s. Since the seventies, the subwavelength confinement of electromagnetic fields as well as their enhancement inherent to the surface plasmon excitation has been widely used for spectroscopic purposes. Recent advances in nano-fabrication, characterization and modelling techniques have allowed unique properties of these surface electromagnetic modes to be explored with respect to subwavelength field localization and waveguiding, opening the path to truly nanoscale plasmonic optical devices. This area of investigation also has interesting links with research on photonic band gap materials and the field of optical metamaterials. Nowadays, plasmonics can be seen as a mature interdisciplinary area of research in which scientists coming from different backgrounds (chemistry, physics, optics and engineering) strive to discover and exploit new and exciting phenomena associated with surface plasmons. The already made and forthcoming discoveries will have impacts in many fields of science and technology, including not only photonics and materials science but also computation, biology and medicine, among others. This focus issue of New Journal of Physics is intended to cover all the aforementioned capabilities of surface plasmons by presenting a current overview of state-of-the-art advances achieved by the leading groups in this field of research. Focus on Plasmonics Contents Directional coupling between dielectric and long-range plasmon waveguides Aloyse Degiron, Sang-Yeon Cho, Talmage Tyler, Nan Marie Jokerst and David R Smith Nanoantenna array-induced fluorescence enhancement and reduced lifetimes Reuben M Bakker, Vladimir P Drachev, Zhengtong Liu, Hsiao-Kuan Yuan, Rasmus H Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph Irudayaraj, Alexander V Kildishev and Vladimir M Shalaev Confinement and propagation characteristics of subwavelength plasmonic modes R F Oulton, G Bartal, D F P Pile and X Zhang Theory on the scattering of light and surface plasmon polaritons by arrays of holes and dimples in a metal film F de León-Pérez, G Brucoli, F J García-Vidal and L Martín-Moreno Shaping and manipulation of light fields with bottom-up plasmonic structures C Girard, E Dujardin, G Baffou and R Quidant Gold nanorods and nanospheroids for enhancing spontaneous emission A Mohammadi, V Sandoghdar and M Agio Generation of surface plasmons at single subwavelength slits: from slit to ridge plasmon J-Y Laluet, A Drezet, C Genet and T W Ebbesen Mode mapping of plasmonic stars using TPL microscopy P Ghenuche, S Cherukulappurath and R Quidant Controlling optical transmission through magneto-plasmonic crystals with an external magnetic field G A Wurtz, W Hendren, R Pollard, R Atkinson, L Le Guyader, A Kirilyuk, Th Rasing, I I Smolyaninov and A V Zayats Nanoplasmonic renormalization and enhancement of Coulomb interactions M Durach, A Rusina, V I Klimov and M I Stockman Bulk and surface sensitivities of surface plasmon waveguides Pierre Berini Mapping plasmons in nanoantennas via cathodoluminescence R Gómez-Medina, N Yamamoto, M Nakano and F J García de Abajo Theoretical analysis of gold nano-strip gap plasmon resonators T Søndergaard, J Jung, S I Bozhevolnyi and G Della Valle Surface plasmon polariton-mediated enhancement of the emission of dye molecules on metallic gratings J Gómez Rivas, G Vecchi and V Giannini Nanoshells to nanoeggs to nanocups: optical properties of reduced symmetry core shell nanoparticles beyond the quasistatic limit Mark W Knight and Naomi J Halas Single emitters coupled to plasmonic nano-antennas: angular emission and collection efficiency T H Taminiau, F D Stefani and N F van Hulst Green's tensor calculations of plasmon resonances of single ho

Bozhevolnyi, Sergey; García-Vidal, Francisco

2008-10-01

172

Decontamination & decommissioning focus area  

SciTech Connect

In January 1994, the US Department of Energy Office of Environmental Management (DOE EM) formally introduced its new approach to managing DOE`s environmental research and technology development activities. The goal of the new approach is to conduct research and development in critical areas of interest to DOE, utilizing the best talent in the Department and in the national science community. To facilitate this solutions-oriented approach, the Office of Science and Technology (EM-50, formerly the Office of Technology Development) formed five Focus AReas to stimulate the required basic research, development, and demonstration efforts to seek new, innovative cleanup methods. In February 1995, EM-50 selected the DOE Morgantown Energy Technology Center (METC) to lead implementation of one of these Focus Areas: the Decontamination and Decommissioning (D & D) Focus Area.

NONE

1996-08-01

173

Tate Online: In Focus  

NSDL National Science Digital Library

The Tate Gallery in London has received numerous accolades for its fine online educational resources, including archived public presentations and lectures. The In Focus website is yet another one of these types of Internet resources, and allows those with an interest in art to hone in on various subjects in greater detail. By looking through their "In Focus" series, visitors may learn about landscape painting in America, the "pop art" movement of the 1960s, and surrealism. A real treat on the site is the "Works in Focus" section, which allows visitors close and contextual appraisals of a number of modern installations, such as Damien Hirst's provocative "Pharmacy" and that most famous painting, "Ophelia" by John Everett Millais. The Millais feature is also notable as it includes a fine interactive timeline of Millais's life, along with a detailed look at the materials and techniques deployed in the creation of this powerful and popular piece of craftsmanship.

174

NICMOS Focus Stability  

NASA Astrophysics Data System (ADS)

++++++++++++++++ Visits 11, 12, 21 have not been corrected for missing POS TARG OFFSET {Jan-19-2005} Visit 22, 13, 31, 32, 41, 42 have been corrected {Jan-19-2005} ++++++++++++++++ The purpose of this activity is to determine if the best focus. This program will execute in one month intervals starting about 1 month after the last execution of proposal 9994 {the previous focus monitoring program}. The program starts with a focus sweep using only the NIC1 camera {visit 11}. The following observation is with the NIC2 camera {visit 12} after about 45 days. This pattern is repeated throughout the period except for Feb 15 where also the NIC3 camera is used. In total this will result in 9 orbits. Notice that VISIT #1 #2 refers to visits for #1 sequential visit number for a given camera #2 camera in question visit 32 is therefore the third visit for camera 2.

Wiklind, Tommy

2004-07-01

175

Sagittal focusing Laue monochromator  

SciTech Connect

An x-ray focusing device generally includes a slide pivotable about a pivot point defined at a forward end thereof, a rail unit fixed with respect to the pivotable slide, a forward crystal for focusing x-rays disposed at the forward end of the pivotable slide and a rearward crystal for focusing x-rays movably coupled to the pivotable slide and the fixed rail unit at a distance rearward from the forward crystal. The forward and rearward crystals define reciprocal angles of incidence with respect to the pivot point, wherein pivoting of the slide about the pivot point changes the incidence angles of the forward and rearward crystals while simultaneously changing the distance between the forward and rearward crystals.

Zhong; Zhong (Stony Brook, NY), Hanson; Jonathan (Wading River, NY), Hastings; Jerome (Stanford, CA), Kao; Chi-Chang (Setauket, NY), Lenhard; Anthony (Medford, NY), Siddons; David Peter (Cutchogue, NY), Zhong; Hui (Coram, NY)

2009-03-24

176

Focus on Basics, 1997.  

ERIC Educational Resources Information Center

Together, these four newsletters contain 36 articles devoted to adult literacy research and practice and the relationship between them. The following articles are included: "A Productive Partnership" (Richard J. Murnane, Bob Bickerton); "Welcome to 'Focus on Basics'" (Barbara Garner); "Applying Research on the Last Frontier" (Karen Backlund, Kathy…

Focus on Basics, 1997

1997-01-01

177

Plasma Focus Device Study.  

National Technical Information Service (NTIS)

A program to determine the X-ray and neutron yields from a plasma focus device as a function of capacitor bank energy was carried out. The capacitor bank energy was varied from 20 kJ to 90 kJ, and empirical scaling laws were determined. In addition, X-ray...

H. F. Rugge D. E. Maxwell S. A. Zwick

1967-01-01

178

Focus: International Economics.  

ERIC Educational Resources Information Center

The "Focus" series, part of the National Council on Economic Education's (NCEE) EconomicsAmerica program, uses economics to enhance learning in subjects such as history, geography, civics, and personal finance, as well as economics. Activities are interactive, reflecting the belief that students learn best through active, highly personalized…

Lynch, Gerald J.; Watts, Michael W.; Wentworth, Donald R.

179

Focus on Dark Matter  

Microsoft Academic Search

This `Focus on Dark Matter' cluster of articles is the very first in a series of featured topics to appear in New Journal of Physics that will be of great interest to the physics community. The idea is to bring together contributions from leading researchers in topical fields to provide insights into the key issues for both experts and non-specialists

Klaus Pretzl

2000-01-01

180

[Focus: Family Communication].  

ERIC Educational Resources Information Center

This issue of the "Journal of the Wisconsin Communication Association" focuses on family communication and contains the following articles: "Marital Typologies: An Alternative Approach to the Study of Communication in Enduring Relations" by Mary Anne Fitzpatrick, "Intimate Communication and the Family" by Marilyn D. LaCourt, and "A Study in…

Barnes, Richard E., Ed.

1977-01-01

181

Neutron focusing using microguides  

NASA Astrophysics Data System (ADS)

Analytical techniques which are dependent solely on the neutron capture reaction rate may be advanced by neutron focusing. We describe a system composed of curved totally reflecting mirrors for the focusing of neutrons by the superposition of intensity transmitted through many thin silicon films, each of which points individually to the desired focus. The acceptance technique shows that the maximum current density is obtained with a large number of microguide sheets of minimum thickness, a short focal length, and a large radius of curvature. This analysis indicates the transmission properties of continuously curved neutron guides as a function of wavelength, and enables the calculation of an estimate of transmission efficiency. Reflection losses increase geometrically with the average number of reflections. The major losses in transmission are caused by misalignment of the layers which diffuse the focus from its theoretical maximum. We propose using 25 ?m thin silicon wafers with a 100 nm coating of nickel, loaded into a cassette specially fabricated to ensure overlapping and to enable a small curvature to be maintained. The length of the system should be as short as possible (˜ few cm) to reduce both reflection losses from the nickel coating and scattering losses in the neutron transmitting medium of silicon.

Mildner, D. F. R.

1990-11-01

182

School Reform. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue addresses school reform, focusing on accountability, attrition, public-supported private education, equitable education, and schoolwide reform. "School-Student Performance and Accountability" (Jose A. Cardenas) discusses what constitutes good performance in school; the shifting emphasis among the input, output, and process of…

IDRA Newsletter, 1998

1998-01-01

183

Curriculum Mapping. Focus On  

ERIC Educational Resources Information Center

This "Focus On" discusses curriculum mapping, a process that allows educators to align the curriculum both within and across grades and to ensure that the curriculum is in line with school, local, and state standards. It outlines the steps of the curriculum mapping process from planning the mapping initiative to creating and editing curriculum…

Molineaux, Rebecca

2008-01-01

184

Focusing of electromagnetic waves.  

National Technical Information Service (NTIS)

The focusing of electromagnetic waves inside a slab has been examined together with two special cases in which the slab is reduced to a single interface or a single medium. To that end the exact solutions for the fields inside a layered medium have been u...

V. Dhayalan

1996-01-01

185

Instructional Technology. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue includes five articles that focus on implementing instructional technology in ways that benefit all students, including limited-English-proficient, minority, economically disadvantaged, and at-risk students. "Cruising the Web with English Language Learners" (Laura Chris Green) presents three scenarios using the World Wide Web in…

IDRA Newsletter, 1997

1997-01-01

186

Focusing educational initiatives  

NASA Technical Reports Server (NTRS)

The United States will soon be facing a critical shortage of aerospace scientists and engineers. To address this problem, Space Grant Colleges can assist in focusing interest in existing educational initiatives and in creating new educational opportunities, particularly for women and underrepresented minorities.

Parks, George K.

1990-01-01

187

Education Policy. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue includes five articles that focus on educational policy in the Texas legislature in relation to student retention, Internet access, and sexual harassment. "1999 Texas Legislative Session--End of an Era?" (Albert Cortez, Maria Robledo Montecel) examines educational equity issues facing legislators: school funding, including the…

IDRA Newsletter, 1998

1998-01-01

188

ENC Focus Review.  

ERIC Educational Resources Information Center

The mission of the Eisenhower National Clearinghouse (ENC) is to identify effective curriculum resources, create high-quality professional development materials, and disseminate useful information and products to improve K-12 mathematics and science teaching and learning. This issue of "ENC Focus" contains articles related to mathematics teaching…

Thorson, Annette, Ed.

189

Focused Ion Beam Fabrication.  

National Technical Information Service (NTIS)

Two types of machines are being used for research in focused ion beam applications. The first system has mass separation and can produce beams of the dopants of Si and GaAs with diameters below 0.1 micrometer. This system, used for ion implantation and li...

J. Melngailis

1988-01-01

190

Equity. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue focuses on equity in children's literature, public funding for private schools, women in educational fields, female dropouts, and the relationship between school violence and family and community violence. "Violence in Our Schools" (Bradley Scott) explores reasons for school violence (media violence, isolation from family, racial…

IDRA Newsletter, 1998

1998-01-01

191

Focusing on the Invisible  

ERIC Educational Resources Information Center

This article seeks to answer the question of whether or not the design and development of an educational laboratory really changes when the focus is on nanotechnology. It explores current laboratory building trends and the added considerations for building a nanotechnology laboratory. The author leaves the reader with additional points to consider…

Haley, Tim R.

2008-01-01

192

Focus: Economic Systems.  

ERIC Educational Resources Information Center

The "Focus" series, part of the National Council on Economic Education's (NCEE) EconomicsAmerica program, uses economics to enhance learning in subjects such as history, geography, civics, and personal finance, as well as economics. Activities are interactive, reflecting the belief that students learn best through active, highly personalized…

McCorkle, Sarapage; Meszaros, Bonnie T.; Odorzynski, Sandra J.; Schug, Mark C.; Watts, Michael

193

Young Children. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue includes five articles that focus on educational, cognitive, and brain research with implications for early childhood educators, including those who work with limited-English-proficient, minority, and economically disadvantaged children. "Coming to Grips with Reading Instruction at the Early Grades" (Christie L. Goodman) reports…

IDRA Newsletter, 1998

1998-01-01

194

An adiabatic focuser  

SciTech Connect

Theoretical analysis is made of an intense relativistic electron beam, such as would be available from a linear collider, moving through a plasma of increasing density, but density always less than that of the beam (underdense). In this situation, the plasma electrons are expelled from the beam channel and the electrons are subject to an ever-increasing focusing force provided by the channel ions. Analysis is made on the beam radiation energy loss in the classical, the transition, and the quantum regimes. It is shown that the focuser is insensitive to the beam energy spread behaviors in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded. The sensitivity of the system to the topic mismatch and the nonlinearity is also analyzed. Examples are given with SLC-type and TLC-type parameters. 9 refs., 1 tab.

Chen, P.; Oide, K.; Sessler, A.M.; Yu, S.S. (Stanford Linear Accelerator Center, Menlo Park, CA (USA); Lawrence Berkeley Lab., CA (USA); Lawrence Livermore National Lab., CA (USA))

1989-08-01

195

Focused ion beam system  

DOEpatents

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 {mu}m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 m or less. 13 figs.

Leung, K.; Gough, R.A.; Ji, Q.; Lee, Y.Y.

1999-08-31

196

Focused ion beam system  

DOEpatents

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 .mu.m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 .mu.m or less.

Leung, Ka-Ngo (Hercules, CA); Gough, Richard A. (Kensington, CA); Ji, Qing (Berkeley, CA); Lee, Yung-Hee Yvette (Berkeley, CA)

1999-01-01

197

Identifying inferences in focus  

Microsoft Academic Search

Conventional approaches to 'the syntax-semantics in terface' concentrate on matching static syntactic structures directly to semantic forms. Th is fails to account for the possibility that underspecified and\\/or procedural meaning may be grammatically encoded, creating observed truth-conditional interpretations only via inferent ial processes. Here I argue that the Hungarian 'focus position' provides evidence for the latter k ind of analysis,

Daniel Wedgwood

198

Globalization in Focus  

NSDL National Science Digital Library

This site comes to the Web courtesy of Foreign Policy in Focus (FPIF, see the September 8, 1998 Scout Report for Social Sciences). Here users will find a more critical look at the WTO as well as the World Bank and the International Monetary Fund (IMF). FPIF here collects links to articles, event announcements, reports, and other resources. Be sure to scroll down the page to see all of the offerings.

2001-01-01

199

Nature Web Focus: SARS  

NSDL National Science Digital Library

The journal Nature offers this free Web focus on Severe Acute Respiratory Syndrome (SARS), in which Nature's reporters pose key questions about the outbreak, and assess our preparedness to deal with future viral threats. Reader will find dozens of articles, including editorials, Science Updates, and Brief Communications from the journal. The articles trace the chronology of the SARS epidemic, and the section titled What Have We Learned? offers an excellent overview of what we know and what remains to be seen.

2007-12-12

200

Recent plasma focus research  

Microsoft Academic Search

The paper shows that the recently reported high pressure limit for the operation of Mather-type plasma focus devices makes discrimination difficult between the scaling laws proposed for the neutron yield. Experimental results are examined, and it is suggested that this limit may explain some well-known contingencies in neutron production. Finally, attention is given to the interpretation of X-ray anisotropy measurements

A. Banuelos; H. Bruzzone; R. Delellis; J. Gratton; R. Gratton; H. Kelly; M. Milanese; J. Pouzo; F. R. Trelles

1979-01-01

201

Unconventional plasma focus devices  

Microsoft Academic Search

The Plasma Focus (PF) characteristics have been investigated in the Two-Guns configuration (TWIN) with a 10-kJ class device. Electrodes with two different heads shapes, hollow (GYN) or hemispherical (PHAL), have been tested and the results show that the neutron yield is greater in the GYN configuration. In simple Two-Guns configuration, with the two anodes facing frontally in the vacuum vessel,

Maurizio Samuelli; Luigi Rapezzi; Maurizio Angelone; Mario Pillon; Massimo Rapisarda; Silvia Vitulli

2006-01-01

202

Transference-focused psychotherapy.  

PubMed

Transference-Focused Psychotherapy (TFP) is a manualized evidence-based treatment for borderline and other severe personality disorders that is based on psychoanalytic object relations theory. The treatment contracting/setting the frame, managing countertransference, and the interpretative process are three critical components of TFP. We provide vignettes to illustrate these techniques and data that support their role in facilitating treatment outcome. PMID:24000869

Yeomans, Frank E; Levy, Kenneth N; Caligor, Eve

2013-09-01

203

Fedgazette Focus: Hog Markets  

NSDL National Science Digital Library

This January 1999 issue of Fedgazette from the Federal Reserve Bank of Minneapolis focuses on the recent downward spiral of hog prices to historic lows in the Midwest. Over ten articles explore pork prices, agricultural finance, and whether or not "agriculture is in crisis" across the nation. Additional links to maps, charts and economic statistics offer other educational resources on the issue from the Ninth Federal Reserve District site.

1999-01-01

204

Subsurface contaminants focus area  

SciTech Connect

The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, including radionuclides, heavy metals; and dense non-aqueous phase liquids (DNAPLs). More than 5,700 known DOE groundwater plumes have contaminated over 600 billion gallons of water and 200 million cubic meters of soil. Migration of these plumes threatens local and regional water sources, and in some cases has already adversely impacted off-site rsources. In addition, the Subsurface Contaminants Focus Area is responsible for supplying technologies for the remediation of numerous landfills at DOE facilities. These landfills are estimated to contain over 3 million cubic meters of radioactive and hazardous buried Technology developed within this specialty area will provide efective methods to contain contaminant plumes and new or alternative technologies for development of in situ technologies to minimize waste disposal costs and potential worker exposure by treating plumes in place. While addressing contaminant plumes emanating from DOE landfills, the Subsurface Contaminants Focus Area is also working to develop new or alternative technologies for the in situ stabilization, and nonintrusive characterization of these disposal sites.

NONE

1996-08-01

205

Enhanced Tumor Uptake and Penetration of Virotherapy Using Polymer Stealthing and Focused Ultrasound  

PubMed Central

Background Oncolytic viruses are among the most powerful and selective cancer therapeutics under development and are showing robust activity in clinical trials, particularly when administered directly into tumor nodules. However, their intravenous administration to treat metastatic disease has been stymied by unfavorable pharmacokinetics and inefficient accumulation in and penetration through tumors. Methods Adenovirus (Ad) was “stealthed” with a new N-(2-hydroxypropyl)methacrylamide polymer, and circulation kinetics were characterized in Balb/C SCID mice (n = 8 per group) bearing human ZR-75-1 xenograft tumors. Then, to noninvasively increase extravasation of the circulating polymer-coated Ad into the tumor, it was coinjected with gas microbubbles and the tumor was exposed to 0.5 MHz focused ultrasound at peak rarefactional pressure of 1.2MPa. These ultrasound exposure conditions were designed to trigger inertial cavitation, an acoustic phenomenon that produces shock waves and can be remotely monitored in real-time. Groups were compared with Student t test or one-way analysis of variance with Tukey correction where groups were greater than two. All statistical tests were two-sided. Results Polymer-coating of Ad reduced hepatic sequestration, infection (>8000-fold; P < .001), and toxicity and improved circulation half-life (>50-fold; P = .001). Combination of polymer-coated Ad, gas bubbles, and focused ultrasound enhanced tumor infection >30-fold; (4×106 photons/sec/cm2; standard deviation = 3×106 with ultrasound vs 1.3×105; standard deviation = 1×105 without ultrasound; P = .03) and penetration, enabling kill of cells more than 100 microns from the nearest blood vessel. This led to substantial and statistically significant retardation of tumor growth and increased survival. Conclusions Combining drug stealthing and ultrasound-induced cavitation may ultimately enhance the efficacy of a range of powerful therapeutics, thereby improving the treatment of metastatic cancer.

2013-01-01

206

Dielectrophoretic columnar focusing device  

DOEpatents

A dielectrophoretic columnar focusing device uses interdigitated microelectrodes to provide a spatially non-uniform electric field in a fluid that generates a dipole within particles in the fluid. The electric field causes the particles to either be attracted to or repelled from regions where the electric field gradient is large, depending on whether the particles are more or less polarizable than the fluid. The particles can thereby be forced into well defined stable paths along the interdigitated microelectrodes. The device can be used for flow cytometry, particle control, and other process applications, including cell counting or other types of particle counting, and for separations in material control.

James, Conrad D. (Albuquerque, NM) [Albuquerque, NM; Galambos, Paul C. (Albuquerque, NM) [Albuquerque, NM; Derzon, Mark S. (Tijeras, NM) [Tijeras, NM

2010-05-11

207

SecurityFocus  

NSDL National Science Digital Library

This news service from SecurityFocus is an excellent resource to learn about important computer security warnings and alerts. The Web site keeps track of many widely used software applications, while reporting known vulnerabilities as they are found. Viruses and worms are another key topic that receives significant attention. Several columns offer expert advice and tips to efficiently use and understand software for different platforms. Government security is covered in the news section, discussing federal practices and legislation related to the national network infrastructure. Because the articles have such a broad scope, the material can be useful for both home and business users.

1999-01-01

208

Focus on magnetoplasmonics  

NASA Astrophysics Data System (ADS)

In this ‘focus on’ collection, a snapshot of the new, fast emerging field of magnetoplasmonics is presented. The research in the field deals with the combination of plasmonics and magnetism to elucidate the fundamentals of spin--plasmon interactions and reach new functionalities such as the enhancement of magneto-optical activity in various materials, active control of plasmons with weak magnetic fields, magnetoplasmonics-based bio- and chemical sensing, magnetophotonic and magnetoplasmonic crystals as modulators of light transmission and reflection, and many others.

Armelles, Gaspar; Dmitriev, Alexandre

2014-04-01

209

Nutrition News Focus  

NSDL National Science Digital Library

Written by David M. Klurfeld, Professor and Chairman of the Department of Nutrition and Food Science at Wayne State University in Detroit, this free, daily newsletter offers concise nutrition tips and analyses of breaking nutrition news. Nutrition News Focus aims at delivering information that ordinary people can use and understand, with a minimum of jargon and no tolerance for "mumbo-jumbo." Users can subscribe to the newsletter at the site. Subscribers receive one short mailing per day, with the topic briefly described and followed by analysis. Old newsletters are added to the archive two weeks after publication, and users can browse the archive by issue date or topic.

210

Focused crossed Andreev reflection  

NASA Astrophysics Data System (ADS)

We consider non-local transport mediated by Andreev reflection in a two-dimensional electron gas (2DEG) connected to one superconducting and two normal metal terminals. A robust scheme is presented for observing crossed Andreev reflection (CAR) between the normal metal terminals based on electron focusing by weak perpendicular magnetic fields. At slightly elevated temperatures the CAR signature can be easily distinguished from a background of quantum interference fluctuations. The CAR-induced entanglement between electrons can be switched on and off over large distances by the magnetic field.

Haugen, H.; Brataas, A.; Waintal, X.; Bauer, G. E. W.

2011-03-01

211

Collective Focusing Ion Accelerator  

NASA Astrophysics Data System (ADS)

The principal subject of this dissertation is the trapping and confinement of pure electron plasmas in bumpy toroidal magnetic fields, with particular attention given to the trapping procedure and the behavior of the plasma during the final equilibrium. The most important aspects of the equilibrium which were studied were the qualitative nature of the plasma configuration and motion and its density, distribution, and stability. The motivation for this study was that an unneutralized cloud of electrons contained in a toroidal system, sufficiently dense and stable, may serve to electrostatically focus ions (against centrifugal and self space-charge forces) in a cyclic ion accelerator. Such an accelerator, known as a Collective Focusing Ion Accelerator (C.F.I.A.), could be far smaller than conventional designs (which use external magnetic fields directly to focus the ions) due to the smaller gyro-radius of an electron in a magnetic field of given strength. A toroidal electric field, induced by a changing magnetic flux, would accelerate the ions. To prevent the electrons from being accelerated and shorting out this field (and possibly instigating a two-stream instability), the strength of the toroidal magnetic field which contains the electrons is given spacial periodicity in the toroidal direction. Suitably prepared electrons will not circulate toroidally in such a "bumpy" field due to the mirror effect of the field maxima. These experiments, then, have involved essentially independent electron clouds contained within the magentic "cells" formed by the bumpy field. Supporting experiments performed in a linear mirror system eliminated the complexity of the gradient inherent in a toroidal field and admitted experiments not possible in a torus. These included performing measurements on electrons ejected out one end. Technical developments in injection were also carried out in this simpler system. The electron cloud generally drifted poloidally at a finite radius from the toroidal minor axis. As this would preclude focusing ions with such clouds, damping this motion was investigated. Finite resistance in the normally perfectly conductive vessel wall did this. In further preparation for a working C.F.I.A., additional experiments studied the effect of ions on the stability of the electron cloud.

Goldin, Fletcher Joshua

212

Focus group on telepharmacy.  

PubMed

The focus group strongly believed that telepharmacy will change the practice of pharmacy and that it is not a matter of if or when but how. Consumers' expectations and the need for efficient health care delivery will drive the use of technology. Pharmacists have considerable lever-age in this technological world because of the money associated with the use of medications. Telepharmacy holds great promise for the profession and should result in greater visibility of pharmacists and enhanced patient access to their services. PMID:11202543

2001-01-15

213

Isoelectric focusing in space  

NASA Technical Reports Server (NTRS)

The potential of space electrophoresis is conditioned by the fact that all electrophoretic techniques require the suppression of gravity-caused convection. Isoelectric focusing (IEF) is a powerful variant of electrophoresis, in which amphoteric substances are separated in a pH gradient according to their isoelectric points. A new apparatus for large scale IEF, utilizing a recycling principle, has been developed. In the ground-based prototype, laminar flow is provided by a series of parallel filter elements. The operation of the apparatus is monitored by an automated array of pH and ultraviolet absorption sensors under control of a desk-top computer. The apparatus has proven to be useful for the purification of a variety of enzymes, snake venom proteins, peptide hormones, and other biologicals, including interferon produced by genetic engineering techniques. In planning for a possible space apparatus, a crucial question regarding electroosmosis needs to be addressed To solve this problem, simple focusing test modules are planned for inclusion in an early Shuttle flight.

Bier, M.; Egen, N. B.; Mosher, R. A.; Twitty, G. E.

1982-01-01

214

Electrostatic Focusing Lens  

NASA Astrophysics Data System (ADS)

We developed an electrostatic focusing lens capable of generating DD reactions, by focusing deuterium ions generated from a pointed emitter at a frozen heavy water target. Due to difficulty with the pointed emitter, we later switched to a hollow cathode design. To model the lenses, chamber, and calculate the dimensions for the design that would maximize ion energy and density, the program SIMION was used. During stable operation, vacuum was hand adjusted around 10-13 mTorr. To keep stable beam, DC voltage generator was varied between 15-25kV. Hand adjusting was necessary, because at points in the operation the frozen heavy water would release vapor at an increased rate. This caused the pressure to rise and the beam current to spike, creating instabilities and an arc to the lens. Three methods were used to determine successful DD production. (1) Two differently shielded Geiger counters (unshielded and UHMW-PE insulated tube), (2) Spectrophotometer comparing control peaks with heavy water tests, and (3) a calibrated bubble dosimeter specific to neutrons. Analysis of the results suggest the neutrons flux varied from 532 to 1.4x10^6 neutrons/ sec, and require further tests to plot and narrow results.

Thomas, Eric; Hopkins, Demitri

2011-11-01

215

Improvement of Detection of Bacterial Pathogens in Normally Sterile Body Sites with a Focus on Orthopedic Samples by Use of a Commercial 16S rRNA Broad-Range PCR and Sequence Analysis  

PubMed Central

A new commercially available universal 16S and 18S rRNA gene PCR test, which is followed by sequence analysis of amplicons (SepsiTest), was evaluated for rapid identification of pathogens in the diagnosis of bone and joint infections. Eighty-three orthopedic samples and 21 specimens from other normally sterile body sites collected from 84 patients were analyzed in parallel by culture and PCR for detection of bacteria and fungi. Compared to culture, the diagnostic sensitivity and specificity of PCR were 88.5% and 83.5%, respectively. The detection rate of PCR (34.6%) was higher than that of bacterial culture (25.0%) as a consequence of the presence of fastidious and noncultivable species in samples and antibiotic treatment of patients. Thirteen culture-negative infections were identified by PCR, and PCR was able to detect culture-proven polymicrobial infections. On the other hand, three samples were culture positive but PCR negative. SepsiTest was demonstrated to be a valuable supplemental tool in the rapid detection of bacteria, especially for fastidious and noncultivable organisms, allowing earlier initiation of pathogen-adapted therapy in patients with bone and joint infections.

Grif, K.; Heller, I.; Lechleitner, K.; Lass-Florl, C.; Orth, D.

2012-01-01

216

Highly Focused Supersonic Microjets  

NASA Astrophysics Data System (ADS)

This paper describes the production of thin, focused microjets with velocities of up to 850m/s by the rapid vaporization of a small mass of liquid in an open liquid-filled capillary. The vaporization is caused by the absorption of a low-energy laser pulse. A likely explanation of the observed phenomenon is based on the impingement of the shock wave caused by the nearly instantaneous vaporization on the free surface of the liquid. We conduct an experimental study of the dependence of the jet velocity on several parameters and develop a semiempirical relation for its prediction. The coherence of the jets and their high velocity, good reproducibility, and controllability are unique features of the system. A possible application is to development of needle-free drug-injection systems that would be of great importance for health care worldwide.

Tagawa, Yoshiyuki; Oudalov, Nikolai; Visser, Claas Willem; Peters, Ivo R.; van der Meer, Devaraj; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

2012-07-01

217

Retroreflection Focusing Schlieren System  

NASA Technical Reports Server (NTRS)

A retroreflective type focusing schlieren system which permits the light source to be positioned on the optic side of the system is introduced. The system includes an extended light source, as opposed to a point source, located adjacent to a beam splitter which projects light through the flow field onto a reflecting grating in the form of a grid which generates sheets of light that are directed back through the flow field and the beam splitter onto a primary lens behind which is located a cut-off grid having a grid pattern which corresponds to the grid pattern of the reflecting grating. The cut-off grid is adjustably positioned behind the primary lens and an image plane for imaging the turbulence is adjustably located behind the cut-off grid.

Heineck, James T. (Inventor)

1996-01-01

218

Focus on granular segregation  

NASA Astrophysics Data System (ADS)

Ordinary fluids mix themselves through thermal motions, or can be even more efficiently mixed by stirring. In contrast, granular materials such as sand often unmix when they are stirred, shaken or sheared. This granular segregation is both a practical means to separate materials in industry, and a persistent challenge to uniformly mixing them. While segregation phenomena are ubiquitous, a large number of different mechanisms have been identified and the underlying physics remains the subject of much inquiry. Particle size, shape, density and even surface roughness can play significant roles. The aim of this focus issue is to provide a snapshot of the current state of the science, covering a wide range of packing densities and driving mechanisms, from thermal-like dilute systems to dense flows.

Daniels, Karen E.; Schröter, Matthias

2013-03-01

219

Focusing on customer service.  

PubMed

This booklet is devoted to a consideration of how good customer service in family planning programs can generate demand for products and services, bring customers back, and reduce costs. Customer service is defined as increasing client satisfaction through continuous concern for client preferences, staff accountability to clients, and respect for the rights of clients. Issues discussed include the introduction of a customer service approach and gaining staff commitment. The experience of PROSALUD in Bolivia in recruiting appropriate staff, supervising staff, soliciting client feedback, and marketing services is offered as an example of a successful customer service approach. The key customer service functions are described as 1) establishing a welcoming atmosphere, 2) streamlining client flow, 3) personalizing client services, and 4) organizing and providing clear information to clients. The role of the manager in developing procedures is explored, and the COPE (Client-Oriented Provider-Efficient) process is presented as a good way to begin to make improvements. Techniques in staff training in customer service include brainstorming, role playing, using case studies (examples of which are provided), and engaging in practice sessions. Training also leads to the development of effective customer service attitudes, and the differences between these and organizational/staff-focused attitudes are illustrated in a chart. The use of communication skills (asking open-ended questions, helping clients express their concerns, engaging in active listening, and handling difficult situations) is considered. Good recovery skills are important when things go wrong. Gathering and using client feedback is the next topic considered. This involves identifying, recording, and discussing customer service issues as well as taking action on these issues and evaluating the results. The booklet ends by providing a sample of customer service indicators, considering the maintenance of a customer service focus, and reporting comments from the reviewers of the booklet. PMID:12320174

1996-01-01

220

Outbound Intrusion Detection  

Microsoft Academic Search

This paper describes a variation to the traditional intrusion detection approach motivated by longstanding challenges and recent trends in information security. Intrusion detection systems have historically focused on the protection of local resources by identifying signs of malicious activity that may help administrators prevent a break-in and limit its effects. Outbound intrusion detection focuses, not on preventing a host from

Salvador Mandujano; Arturo Galv

221

Latin-Focus  

NSDL National Science Digital Library

Launched in 1998, Latin-Focus "enables executives and research analysts alike to find the latest available data from government sources, economic forecasts, market analysis covering economic performance, political risk assessments and financial market developments" in Latin American countries. The front page of the site offers current data as well as daily news and commentary. In the News and Commentary section, the title and source of the article are given, along with the subject country and language. Past articles are archived by date, although the site does note that news briefs may have expired. News may also be searched by country. Along the left side of the screen, eight countries, including Argentina, Brazil, Mexico, and Venezuela, are highlighted. Clicking on one of these countries will bring up a menu consisting of Economic Indicators, Economic Forecasts, Release Calendar, Economic Briefing, Fact Sheet, and Web Directory. Each of these topics links to further subtopics or a variety of short online reports and graphs. This well-designed site offers clear, basic information for those studying economic issues in Latin America.

222

COMPRENDO: Focus and approach.  

PubMed

Tens of thousands of man-made chemicals are in regular use and discharged into the environment. Many of them are known to interfere with the hormonal systems in humans and wildlife. Given the complexity of endocrine systems, there are many ways in which endocrine-disrupting chemicals (EDCs) can affect the body's signaling system, and this makes unraveling the mechanisms of action of these chemicals difficult. A major concern is that some of these EDCs appear to be biologically active at extremely low concentrations. There is growing evidence to indicate that the guiding principle of traditional toxicology that "the dose makes the poison" may not always be the case because some EDCs do not induce the classical dose-response relationships. The European Union project COMPRENDO (Comparative Research on Endocrine Disrupters--Phylogenetic Approach and Common Principles focussing on Androgenic/Antiandrogenic Compounds) therefore aims to develop an understanding of potential health problems posed by androgenic and antiandrogenic compounds (AACs) to wildlife and humans by focusing on the commonalities and differences in responses to AACs across the animal kingdom (from invertebrates to vertebrates) . PMID:16818253

Schulte-Oehlmann, Ulrike; Albanis, Triantafyllos; Allera, Axel; Bachmann, Jean; Berntsson, Pia; Beresford, Nicola; Carnevali, Daniela Candia; Ciceri, Francesca; Dagnac, Thierry; Falandysz, Jerzy; Galassi, Silvana; Hala, David; Janer, Gemma; Jeannot, Roger; Jobling, Susan; King, Isabella; Klingmüller, Dietrich; Kloas, Werner; Kusk, Kresten Ole; Levada, Ramon; Lo, Susan; Lutz, Ilka; Oehlmann, Jörg; Oredsson, Stina; Porte, Cinta; Rand-Weaver, Marian; Sakkas, Vasilis; Sugni, Michela; Tyler, Charles; van Aerle, Ronny; van Ballegoy, Christoph; Wollenberger, Leah

2006-04-01

223

Focusing on flu  

PubMed Central

School-located immunization programs (SLIP) will only be successful if parents consent to their children's participation. It is critical to understand parent perspectives regarding the factors that make them more or less likely to provide that consent. Organizations creating SLIPs will be able to capitalize on the aspects of SLIPs that parents appreciate, and address and correct issues that may give rise to parent concerns. This study involved five focus groups among the parents of school students in a large, urban school district. Findings highlight the broad range of concepts important to parents when considering participation in a SLIP. The safety and trust issues regarding vaccines in general that are so important to parents are also important to parents when considering participation in a SLIP. Effective communication strategies that include assurances regarding tracking of information and the competence and experience of immunizers will be helpful when addressing parents regarding SLIPs. In addition, parents were very cognizant of and positive regarding the public health benefits associated with SLIPs. Further study among larger populations of parents will further refine these ideas and aid in the development of successful influenza vaccine SLIPs that directly address and communicate with parents about the issues most important to them.

Middleman, Amy B.; Short, Mary B.; Doak, Jean S.

2012-01-01

224

EDITORIAL: Focus on Graphene  

NASA Astrophysics Data System (ADS)

Graphene physics is currently one of the most active research areas in condensed matter physics. Countless theoretical and experimental studies have already been performed, targeting electronic, magnetic, thermal, optical, structural and vibrational properties. Also, studies that modify pristine graphene, aiming at finding new physics and possible new applications, have been considered. These include patterning nanoribbons and quantum dots, exposing graphene's surface to different chemical species, studying multilayer systems, and inducing strain and curvature (modifying in this way graphene's electronic properties). This focus issue includes many of the latest developments on graphene research. Focus on Graphene Contents Electronic properties of graphene and graphene nanoribbons with 'pseudo-Rashba' spin-orbit coupling Tobias Stauber and John Schliemann Strained graphene: tight-binding and density functional calculations R M Ribeiro, Vitor M Pereira, N M R Peres, P R Briddon and A H Castro Neto The effect of sublattice symmetry breaking on the electronic properties of doped graphene A Qaiumzadeh and R Asgari Interfaces within graphene nanoribbons J Wurm, M Wimmer, I Adagideli, K Richter and H U Baranger Weak localization and transport gap in graphene antidot lattices J Eroms and D Weiss Electronic properties of graphene antidot lattices J A Fürst, J G Pedersen, C Flindt, N A Mortensen, M Brandbyge, T G Pedersen and A-P Jauho Splitting of critical energies in the n=0 Landau level of graphene Ana L C Pereira Double-gated graphene-based devices S Russo, M F Craciun, M Yamamoto, S Tarucha and A F Morpurgo Pinning and switching of magnetic moments in bilayer graphene Eduardo V Castro, M P López-Sancho and M A H Vozmediano Electronic transport properties of graphene nanoribbons Katsunori Wakabayashi, Yositake Takane, Masayuki Yamamoto and Manfred Sigrist Many-body effects on out-of-plane phonons in graphene J González and E Perfetto Graphene zigzag ribbons, square lattice models and quantum spin chains Mahdi Zarea and Nancy Sandler On the universal ac optical background in graphene V P Gusynin, S G Sharapov and J P Carbotte Heat conduction in graphene: experimental study and theoretical interpretation S Ghosh, D L Nika, E P Pokatilov and A A Balandin Calculation of the Raman G peak intensity in monolayer graphene: role of Ward identities D M Basko Electronic transport in bilayer graphene Mikito Koshino Magnetic Kronig-Penney model for Dirac electrons in single-layer graphene M Ramezani Masir, P Vasilopoulos and F M Peeters Electrical transport in high-quality graphene pnp junctions Jairo Velasco Jr, Gang Liu, Wenzhong Bao and Chun Ning Lau Local density of states and scanning tunneling currents in graphene N M R Peres, Ling Yang and Shan-Wen Tsai Gaps and tails in graphene and graphane B Dóra and K Ziegler Quasi-ferromagnet spintronics in the graphene nanodisc-lead system Motohiko Ezawa Range and correlation effects in edge disordered graphene nanoribbons Alessandro Cresti and Stephan Roche Remarks on the tight-binding model of graphene Cristina Bena and Gilles Montambaux

Peres, N. M. R.; Ribeiro, Ricardo M.

2009-09-01

225

Spatio-temporal analysis of molecular delivery through the blood brain barrier using focused ultrasound  

NASA Astrophysics Data System (ADS)

The deposition of gadolinium through ultrasound-induced blood-brain barrier (BBB) openings in the murine hippocampus was investigated. First, wave propagation simulations through the intact mouse skull revealed minimal beam distortion while thermal deposition simulations, at the same sonication parameters used to induce BBB opening in vivo, revealed temperature increases lower than 0.5 °C. The simulation results were validated experimentally in ex vivo skulls (m = 6) and in vitro tissue specimens. Then, in vivo mice (n = 9) were injected with microbubbles (Optison™ 25-50 µl) and sonicated (frequency: 1.525 MHz, pressure amplitudes: 0.5-1.1 MPa, burst duration: 20 ms, duty cycle: 20%, durations: 2-4 shots, 30 s per shot, 30 s interval) at the left hippocampus, through intact skin and skull. Sequential, high-resolution, T1-weighted MRI (9.4 Tesla, in-plane resolution: 75 µm, scan time: 45-180 min) with gadolinium (Omniscan™ 0.5 ml) injected intraperitoneally revealed a threshold of the BBB opening at 0.67 MPa and BBB closing within 28 h from opening. The contrast-enhancement area and gadolinium deposition path were monitored over time and the influence of vessel density, size and location was determined. Sonicated arteries, or their immediate surroundings, depicted greater contrast enhancement than sonicated homogeneous brain tissue regions. In conclusion, gadolinium was delivered through a transiently opened BBB and contained to a specific brain region (i.e., the hippocampus) using a single-element focused ultrasound transducer. It was also found that the amount of gadolinium deposited in the hippocampal region increased with the acoustic pressure and that the spatial distribution of the BBB opening was determined not only by the ultrasound beam, but also by the vasculature of the targeted brain region.

Choi, J. J.; Pernot, M.; Brown, T. R.; Small, S. A.; Konofagou, E. E.

2007-09-01

226

Cable Diagnostic Focused Initiative  

SciTech Connect

This report summarizes an extensive effort made to understand how to effectively use the various diagnostic technologies to establish the condition of medium voltage underground cable circuits. These circuits make up an extensive portion of the electric delivery infrastructure in the United States. Much of this infrastructure is old and experiencing unacceptable failure rates. By deploying efficient diagnostic testing programs, electric utilities can replace or repair circuits that are about to fail, providing an optimal approach to improving electric system reliability. This is an intrinsically complex topic. Underground cable systems are not homogeneous. Cable circuits often contain multiple branches with different cable designs and a range of insulation materials. In addition, each insulation material ages differently as a function of time, temperature and operating environment. To complicate matters further, there are a wide variety of diagnostic technologies available for assessing the condition of cable circuits with a diversity of claims about the effectiveness of each approach. As a result, the benefits of deploying cable diagnostic testing programs have been difficult to establish, leading many utilities to avoid the their use altogether. This project was designed to help address these issues. The information provided is the result of a collaborative effort between Georgia Tech NEETRAC staff, Georgia Tech academic faculty, electric utility industry participants, as well as cable system diagnostic testing service providers and test equipment providers. Report topics include: •How cable systems age and fail, •The various technologies available for detecting potential failure sites, •The advantages and disadvantages of different diagnostic technologies, •Different approaches for utilities to employ cable system diagnostics. The primary deliverables of this project are this report, a Cable Diagnostic Handbook (a subset of this report) and an online knowledge based system (KBS) that helps utilities select the most effective diagnostic technologies for a given cable circuit and circuit conditions.

Hartlein, R.A.; Hampton, R.N.

2010-12-30

227

The evaluation of text quality: expert-focused and reader-focused methods compared  

Microsoft Academic Search

The authors compare a reader-focused text evaluation with an expert-focused evaluation by technical writers and subject\\/audience experts. The experts were asked to predict the problems readers had signaled in a government brochure about alcohol. On average, they predicted less than 15% of the reader problems and produced a lot of new problem detections. In addition, the experts showed little mutual

L EO LENTZ; MENNO DE JONG

1997-01-01

228

Focus point supersymmetry in extended gauge mediation  

NASA Astrophysics Data System (ADS)

We propose a small extension of the minimal gauge mediation through the combination of extended gauge mediation and conformal sequestering. We show that the focus point supersymmetry can be realized naturally, and the fine tuning is significantly reduced compared to the minimal gauge mediation and extended gauge mediation without focus point. The Higgs boson mass is around 125 GeV, the gauginos remain light, and the gluino is likely to be detected at the next run of the LHC. However, the multi-TeV squarks is out of the reach of the LHC. The numerical calculation for fine-tuning shows that this model remains natural.

Ding, Ran; Li, Tianjun; Staub, Florian; Zhu, Bin

2014-03-01

229

Isoelectric focusing of proteins and peptides  

NASA Technical Reports Server (NTRS)

Egg-white solution was chosen as the reference solution in order to assess the effects of operational parameters (voltage, flow rate, ampholine pH range and concentration, and protein concentration) of the RIEF apparatus on protein resolution. Topics of discussion include: (1) comparison of RIEF apparatus to conventional IEF techniques (column and PAG) with respect to resolution and throughput; (2) peptide and protein separation (AHF, Thymosin - Fraction 5, vasoactive peptide, L-asparaginase and ACP); and (3) detection of peptides - dansyl derivatives of amino acids and peptides, post-focusing fluorescent labeling of amino acids, peptides and proteins, and ampholine extraction from focused gels.

Egen, N.

1979-01-01

230

A study on the flip angle for an optimal T1-weighted image based on the 3D-THRIVE MRI technique: Focusing on the detection of a hepatocellular carcinoma (HCC)  

NASA Astrophysics Data System (ADS)

This study examined the optimal flip angle (FA) for a T1-weighted image in the detection of a hepatocellular carcinoma (HCC). A 3D-T1-weighted high-resolution isotropic volume examination (THRIVE) technique was used to determine the dependence of the signal to noise ratio (SNR) and the contrast-to-noise ratio (CNR) on the change in FA. This study targeted 40 liver cancer patients (25 men and 15 women aged 50 to 70 years with a mean age of 60.32 ± 6.2 years) who visited this hospital to undergo an abdominal MRI examination from January to June 2013. A 3.0 Tesla MRI machine (Philips, Medical System, Achieva) and a MRI receiver coil for data reception with a 16-channel multicoil were used in this study. The THRIVE (repetition time (TR): 8.1 ms, echo time (TE): 3.7 ms, matrix: 172 × 172, slice thickness: 4 mm, gap: 2 mm, field of view (FOV): 350 mm, and band width (BW): 380.1 Hz) technique was applied as a pulse sequence. The time required for the examination was 19 seconds, and the breath-hold technique was used. Axial images were obtained at five FAs: 5, 10, 15, 20 and 25°. The signal intensities of the liver, the lesion and the background noise were measured based on the acquired images before the SNR and the CNR were calculated. To evaluate the image at the FA, we used SPSS for Windows ver. 17.0 to conduct a one-way ANOVA test. A Bonferroni test was conducted as a post-hoc test. The SNRs of the hemorrhagic HCC in the 3D-THRIVE technique were 35.50 ± 4.12, 97.00 ± 10.24, 66.09 ± 7.29, 53.84 ± 5.43, and 42.92 ± 5.11 for FAs of 5, 10, 15, 20, and 25°, respectively (p = 0.0430), whereas the corresponding CNRs were 30.50 ± 3.84, 43.00 ± 5.42, 36.54 ± 4.09, 32.30 ± 2.79, and 31.69 ± 3.21 (p = 0.0003). At a small FA of 10, the SNR and the CNR showed the highest values. As the FA was increased, the SNR and the CNR values showed a decreasing tendency. In conclusion, the optimal T1-weighted image FA should be set to 10° to detect a HCC by using the 3D-THRIVE abdominal MRI technique.

Dong, Kyung-Rae; Goo, Eun-Hoe; Lee, Jae-Seung; Chung, Woon-Kwan; Kim, Young-Jae

2014-04-01

231

Microflow Cytometers with Integrated Hydrodynamic Focusing  

PubMed Central

This study demonstrates the suitability of microfluidic structures for high throughput blood cell analysis. The microfluidic chips exploit fully integrated hydrodynamic focusing based on two different concepts: Two-stage cascade focusing and spin focusing (vortex) principle. The sample—A suspension of micro particles or blood cells—is injected into a sheath fluid streaming at a substantially higher flow rate, which assures positioning of the particles in the center of the flow channel. Particle velocities of a few m/s are achieved as required for high throughput blood cell analysis. The stability of hydrodynamic particle positioning was evaluated by measuring the pulse heights distributions of fluorescence signals from calibration beads. Quantitative assessment based on coefficient of variation for the fluorescence intensity distributions resulted in a value of about 3% determined for the micro-device exploiting cascade hydrodynamic focusing. For the spin focusing approach similar values were achieved for sample flow rates being 1.5 times lower. Our results indicate that the performances of both variants of hydrodynamic focusing suit for blood cell differentiation and counting. The potential of the micro flow cytometer is demonstrated by detecting immunologically labeled CD3 positive and CD4 positive T-lymphocytes in blood.

Frankowski, Marcin; Theisen, Janko; Kummrow, Andreas; Simon, Peter; Ragusch, Hulya; Bock, Nicole; Schmidt, Martin; Neukammer, Jorg

2013-01-01

232

Range from focus-error  

Microsoft Academic Search

We derive theoretically and demonstrate experimentally an approach to range-from-focus with an important improvement over all previous methods. Previous methods rely on subjective measures of sharpness to focus a selected locale of the image. Our method uses measured physical features of the optical signal to generate an objective focus-error distance map. To compute range-from-focus-error distance it is not necessary to

M. W. Siegel; M. L. Leary

233

AADD-FOCUSED Mailing List  

NSDL National Science Digital Library

The AADD-FOCUSED mailing list is an unmoderated focused discussion list for adults who have ADD (Attention Deficit Disorder). Although there are other forums available for discussion of ADD-related topics, they are often too broadly defined and receive many postings not having to do with Adult ADD. Therefore AADD-FOCUSED has been created specifically for those who wish to read fewer, more focused messages per day on the subject of Adult ADD.

234

Focusing Electron Beams at SLAC.  

ERIC Educational Resources Information Center

Describes the development of a set of magnets that focus high-energy electron and positron beams causing them to collide, annihilate each other, and generate new particles. Explains how dipoles bend the beam, how quadrupoles focus the beam, how the focal length is calculated, and the superconducting final focus. (MDH)

Taylor, Richard L.

1993-01-01

235

Pyramid based depth from focus  

Microsoft Academic Search

A method is presented for depth recovery through the analysis of scene sharpness across changing focus position. Modeling a defocused image as the application of a low pass-filter on a properly focused image of the same scene, the authors can compare the high spatial frequency content of regions in each image and determine the correct focus position. Recovering depth in

Trevor Darrell; Kwangyoen Wohn

1988-01-01

236

Neutron focusing optic for submillimeter materials analysis  

SciTech Connect

A neutron lens constructed with polycapillary glass fibers is used to focus a 50[times]45 mm[sup 2] beam exiting a cold neutron guide onto a spot of 0.53 mm (full width at half maximum) with a current density gain of 80. The characteristics of the lens are presented. This lens is designed to enhance the detection limit and lateral resolution for prompt gamma activation analysis using cold neutron beams.

Xiao, Q.F. (X-Ray Optical Systems, Inc., Albany, New York 12205 (United States)); Chen, H. (National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)); Sharov, V.A. (X-Ray Optical Systems, Inc., Albany, New York 12205 (United States)); Mildner, D.F.R.; Downing, R.G. (National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)); Gao, N.; Gibson, D.M. (X-Ray Optical Systems, Inc., Albany, New York 12205 (United States))

1994-11-01

237

Power Evaluation of Focused Cluster Tests  

PubMed Central

Many statistical tests have been developed to assess the significance of clusters of disease located around known sources of environmental contaminants, also known as focused disease clusters. The majority of focused-cluster tests were designed to detect a particular spatial pattern of clustering, one in which the disease cluster centers around the pollution source and declines in a radial fashion with distance. However, other spatial patterns of environmentally related disease clusters are likely given that the spatial dispersion patterns of environmental contaminants, and thus human exposure, depend on a number of factors (i.e., meteorology and topography). For this study, data were simulated with five different spatial patterns of disease clusters, reflecting potential pollutant dispersion scenarios: 1) a radial effect decreasing with increasing distance, 2) a radial effect with a defined peak and decreasing with distance, 3) a simple angular effect, 4) an angular effect decreasing with increasing distance and 5) an angular effect with a defined peak and decreasing with distance. The power to detect each type of spatially distributed disease cluster was evaluated using Stone’s Maximum Likelihood Ratio Test, Tango's Focused Test, Bithell's Linear Risk Score Test, and variations of the Lawson-Waller Score Test. Study findings underscore the importance of considering environmental contaminant dispersion patterns, particularly directional effects, with respect to focused-cluster test selection in cluster investigations. The effect of extra variation in risk also is considered, although its effect is not substantial in terms of the power of tests.

Puett, RC; Lawson, AB; Clark, AB; Hebert, JR; Kulldorff, M

2012-01-01

238

EDITORIAL: Focus on Quantum Control  

NASA Astrophysics Data System (ADS)

Control of quantum phenomena has grown from a dream to a burgeoning field encompassing wide-ranging experimental and theoretical activities. Theoretical research in this area primarily concerns identification of the principles for controlling quantum phenomena, the exploration of new experimental applications and the development of associated operational algorithms to guide such experiments. Recent experiments with adaptive feedback control span many applications including selective excitation, wave packet engineering and control in the presence of complex environments. Practical procedures are also being developed to execute real-time feedback control considering the resultant back action on the quantum system. This focus issue includes papers covering many of the latest advances in the field. Focus on Quantum Control Contents Control of quantum phenomena: past, present and future Constantin Brif, Raj Chakrabarti and Herschel Rabitz Biologically inspired molecular machines driven by light. Optimal control of a unidirectional rotor Guillermo Pérez-Hernández, Adam Pelzer, Leticia González and Tamar Seideman Simulating quantum search algorithm using vibronic states of I2 manipulated by optimally designed gate pulses Yukiyoshi Ohtsuki Efficient coherent control by sequences of pulses of finite duration Götz S Uhrig and Stefano Pasini Control by decoherence: weak field control of an excited state objective Gil Katz, Mark A Ratner and Ronnie Kosloff Multi-qubit compensation sequences Y Tomita, J T Merrill and K R Brown Environment-invariant measure of distance between evolutions of an open quantum system Matthew D Grace, Jason Dominy, Robert L Kosut, Constantin Brif and Herschel Rabitz Simplified quantum process tomography M P A Branderhorst, J Nunn, I A Walmsley and R L Kosut Achieving 'perfect' molecular discrimination via coherent control and stimulated emission Stephen D Clow, Uvo C Holscher and Thomas C Weinacht A convenient method to simulate and visually represent two-photon power spectra of arbitrarily and adaptively shaped broadband laser pulses M A Montgomery and N H Damrauer Accurate and efficient implementation of the von Neumann representation for laser pulses with discrete and finite spectra Frank Dimler, Susanne Fechner, Alexander Rodenberg, Tobias Brixner and David J Tannor Coherent strong-field control of multiple states by a single chirped femtosecond laser pulse M Krug, T Bayer, M Wollenhaupt, C Sarpe-Tudoran, T Baumert, S S Ivanov and N V Vitanov Quantum-state measurement of ionic Rydberg wavepackets X Zhang and R R Jones On the paradigm of coherent control: the phase-dependent light-matter interaction in the shaping window Tiago Buckup, Jurgen Hauer and Marcus Motzkus Use of the spatial phase of a focused laser beam to yield mechanistic information about photo-induced chemical reactions V J Barge, Z Hu and R J Gordon Coherent control of multiple vibrational excitations for optimal detection S D McGrane, R J Scharff, M Greenfield and D S Moore Mode selectivity with polarization shaping in the mid-IR David B Strasfeld, Chris T Middleton and Martin T Zanni Laser-guided relativistic quantum dynamics Chengpu Liu, Markus C Kohler, Karen Z Hatsagortsyan, Carsten Muller and Christoph H Keitel Continuous quantum error correction as classical hybrid control Hideo Mabuchi Quantum filter reduction for measurement-feedback control via unsupervised manifold learning Anne E B Nielsen, Asa S Hopkins and Hideo Mabuchi Control of the temporal profile of the local electromagnetic field near metallic nanostructures Ilya Grigorenko and Anatoly Efimov Laser-assisted molecular orientation in gaseous media: new possibilities and applications Dmitry V Zhdanov and Victor N Zadkov Optimization of laser field-free orientation of a state-selected NO molecular sample Arnaud Rouzee, Arjan Gijsbertsen, Omair Ghafur, Ofer M Shir, Thomas Back, Steven Stolte and Marc J J Vrakking Controlling the sense of molecular rotation Sharly Fleischer, Yuri Khodorkovsky, Yehiam Prior and Ilya Sh Averbukh Optimal control of interacting particles: a

Rabitz, Herschel

2009-10-01

239

Focus Groups Help To Focus the Marketing Strategy.  

ERIC Educational Resources Information Center

A university-based degree completion program for adults conducted focus group research to refine market positioning and promotion. Focus groups averaged five current students and recent graduates who reflected, demographically, the current student population. Results gave insight into reasons for selecting the university, aspects of the program…

Ashar, Hanna; Lane, Maureen

1996-01-01

240

Shifting focus: Assessing cataloging service through focus groups  

Microsoft Academic Search

Focus groups are a valuable research tool for evaluating library services but they are overlooked as a means of analyzing the performance of internal library units like technical services. In this study, focus group meetings were held with departmental library personnel to gather data related to the perception of centralized cataloging services in the decentralized library system at the University

K. C. Elhard; Qiang Jin

2004-01-01

241

MR imaging of shear waves generated by focused ultrasound  

Microsoft Academic Search

1 This study has shown that magnetic resonance elastography (MRE) can detect shear waves excited by focused ultrasound (FUS) in both gel phantoms and ex vivo muscle. Good agree- ment was shown between the shear modulus measured from MRE images generated using FUS and that using previously reported MRE techniques. The shear wave displacement ampli- tude at the FUS focus

Tao Wu; Joel P. Felmlee; James F. Greenleaf; Stephen J. Riederer; Richard L. Ehman

2000-01-01

242

Ultrasonic inspection apparatus and method using a focused wave device  

DOEpatents

An ultrasonic pulse echo inspection apparatus and method for detecting structural failures. A focus lens is coupled to the transducer to focus the ultrasonic signal on an area to be inspected and a stop is placed in the focus lens to block selected ultrasonic waves. Other waves are not blocked and are transmitted through the structure to arrive at interfaces therein concurrently to produce an echo response with significantly less distortion.

Gieske, John H. (Albuquerque, NM); Roach, Dennis P. (Albuquerque, NM); Walkington, Phillip D. (Albuquerque, NM)

2001-01-01

243

Fast-moving laser focus  

Microsoft Academic Search

If a laser pulse is passed through a nonlinear medium, its focus can move rapidly. The paraxial-ray approximation is used to calculate analytically the position and radius of a moving laser focus as a function of time-dependent laser power and properties of the nonlinear medium.

F. S. Felber; G. Busse; Hochschule der Bundeswehr Munchen

1980-01-01

244

Absolute focus lock for microscopes  

NASA Technical Reports Server (NTRS)

Mechanism absolutely immobilizes microscope stage at a preset focus, preserving focus indefinitely. The lock is a second-class lever consisting of a straight body having a fulcrum with a cylindrical bearing surface at one end and a thumbscrew at the other end.

Cone, C. D., Jr.; Loop, R. W.; Tongier, M., Jr.

1970-01-01

245

Detecting and Understanding Differences in Postural Sway. Focus on \\  

Microsoft Academic Search

Postural sway during quiet standing reflects the interplay between destabilizing forces acting on the body and actions by the postural control system to prevent a loss of balance. Hence, balance impairments caused by altered sensory, motor, or central nervous function related to such factors as older age and pathology (e.g., Parkinson's disease, peripheral neuropathy) will be reflected in altered characteristics

Michael J. Pavol

2004-01-01

246

Compact electron beam focusing column  

SciTech Connect

A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

2001-07-13

247

Focus and VP Ellipsis1  

PubMed Central

In spoken English, pitch accents can convey the focus associated with new or contrasted constituents. Two listening experiments were conducted to determine whether accenting a subject makes its predicate a more tempting antecedent for an elided verb phrase, presumably because the accent helps focus the subject of the antecedent clause, increasing its likelihood of contrasting with the subject of the elided clause. The results of Experiment 1 supported the predictions of this “contrasted remnant hypothesis” but in principle could also be caused by listeners avoiding antecedents containing a focused (F-marked) constituent. Experiment 2 disconfirmed the hypothesis that listeners avoid antecedents containing a focused constituent, although pitch accents within a potential antecedent VP affected ellipsis resolution.

Frazier, Lyn; Clifton, Charles; Carlson, Katy

2006-01-01

248

Focusing light through living tissue  

NASA Astrophysics Data System (ADS)

Tissues such as skin, fat or cuticle are non-transparent because inhomogeneities in the tissue scatter light. We demonstrate experimentally that light can be focused through turbid layers of living tissue, in spite of scattering. Our method is based on the fact that coherent light forms an interference pattern, even after hundreds of scattering events. By spatially shaping the wavefront of the incident laser beam, this interference pattern was modified to make the scattered light converge to a focus. In contrast to earlier experiments, where light was focused through solid objects, we focused light through living pupae of Drosophila melanogaster. We discuss a dynamic wavefront shaping algorithm that follows changes due to microscopic movements of scattering particles in real time. We relate the performance of the algorithm to the measured timescale of the changes in the speckle pattern and analyze our experiment in the light of Laser Doppler flowmetry. Applications in particle tracking, imaging, and optical manipulation are discussed.

Vellekoop, I. M.; Aegerter, C. M.

2010-02-01

249

Wayside Teaching: Focusing on Relationships  

ERIC Educational Resources Information Center

Wayside teaching focuses on building and maintaining positive relationships with students. Teachers can implement certain wayside teaching practices to end the year in a positive way and begin preparing for the next school year.

Powell, Sara Davis

2011-01-01

250

Wolter Optics for Neutron Focusing  

NASA Technical Reports Server (NTRS)

Focusing optics based on Wolter optical geometries developed for x-ray grazing incidence beams can be designed for neutron beams. Wolter optics are formed by grazing incidence reflections from two concentric conic sections (for example, a paraboloid and a hyperboloid). This has transformed observational X-ray astronomy by increasing the sensitivity by many orders of magnitude for research in astrophysics and cosmology. To increase the collection area, many reflecting mirrors of different diameters are nested with a common focal plane. These mirrors are fabricated using nickel-electroformed replication techniques. We apply these ideas to neutron focusing using nickel mirrors. We show an initial test of a conical mirror using a beam of cold neutrons. key words: electroformed nickel replication, focusing optics, grazing angle incidence, mirror reflection, neutron focusing, Wolter optics

Mildner, D. F. R.; Gubarev, M. V.

2010-01-01

251

Isoelectric Focusing in a Drop  

PubMed Central

A novel approach to molecular separations is investigated using a technique termed droplet-based isoelectric focusing. Drops are manipulated discretely on a superhydrophobic surface, subjected to low voltages for isoelectric focusing, and split—resulting in a preparative separation. A universal indicator dye demonstrates the generation of stable, reversible pH gradients (3–10) in ampholyte buffers and these gradients lead to protein focusing within the drop length. Focusing was visually characterized, spectroscopically verified, and assessed quantitatively by non-invasive light scattering measurements. It was found to correlate with a quantitative model based on 1D steady state theory. This work illustrates that molecular separations can be deployed within a single open drop and the differential fractions can be separated into new discrete liquid elements.

Weiss, Noah G.; Hayes, Mark A.; Garcia, Antonio A.; Ansari, Rafat R.

2010-01-01

252

Nursing education: focus on flexibility.  

PubMed

Curricular change requires input from both service and education. However, it is sometimes difficult to obtain a complete picture of nursing practice from the clinical arena. The curriculum committee of the University of San Diego Philip Y. Hahn School of Nursing conducted a study with focus groups comprised of nurses from several different areas of practice to obtain information for curriculum changes. Both the focus group process and its outcomes are reported here. Flexibility was the key theme that emerged from all of the focus group sessions. Other themes were categorized in terms of issues addressed and included professional issues, healthcare systems issues, nursing education issues, and advanced practice issues. The focus group strategy proved to be an effective means of gaining the broad spectrum of insights needed for curriculum revision. PMID:9067868

Clark, M J

1997-03-01

253

Developing a Focused Research Effort.  

ERIC Educational Resources Information Center

The author discusses a method to produce a cluster of focused nursing research projects. Her method includes (1) focal topic identification, (2) development, (3) communication, (4) integration, (5) collaboration, and (6) balance. (CH)

Lenz, Elizabeth R.

1987-01-01

254

Line-Focus Sun Trackers.  

National Technical Information Service (NTIS)

Sun trackers have been a troublesome component for line-focus concentrating collector systems. The problems have included poor accuracy, component failures, false locks on clouds, and restricted tracker operating ranges. In response to these tracking diff...

R. Gee

1980-01-01

255

Focusing on Contact Lens Safety  

MedlinePLUS

... E-mail Consumer Updates RSS Feed Focusing on Contact Lens Safety Search the Consumer Updates Section Print & ... Updates RSS Feed On this page Types of Contact Lenses Getting a Prescription Tips for Buying Proper ...

256

Qualitative research. Introducing focus groups.  

PubMed Central

This paper introduces focus group methodology, gives advice on group composition, running the groups, and analysing the results. Focus groups have advantages for researchers in the field of health and medicine: they do not discriminate against people who cannot read or write and they can encourage participation from people reluctant to be interviewed on their own or who feel they have nothing to say. Images p301-a

Kitzinger, J.

1995-01-01

257

Near-field focusing plates  

Microsoft Academic Search

Using a modulated grating-like surface, referred to as a near-field focusing plate, we experimentally demonstrate focusing well beyond the diffraction limit. The reported near-field plate achieves a resolution of ap lambda0\\/20 at a frequency of 1.027 GHz, where lambda0 is the free space wavelength. Along with these experimental results, the intrinsic properties of near-field plates are reviewed and a general

Anthony Grbic; Lei Jiang; Roberto Merlin

2008-01-01

258

Oculometer focus and mirror control  

NASA Technical Reports Server (NTRS)

An automatic focusing system designed around an ultrasonic range measurement is described. Besides maintaining the focus, subject distance is a by-product which could lighten the NOVA computational effort. An automatic head tracking unit is also discussed. It is intended to reduce the search time required when track is lost. An X-Y ultrasonic measurement is also made in this design to control the deflection mirrors.

Guy, W. J.

1982-01-01

259

Focused X-shaped pulses  

Microsoft Academic Search

The space-time focusing of a (continuous) succession of localized X-shaped pulses is obtained by suitably integrating over their speed, i.e., over their axicon angle, thus generalizing a previous (discrete) approach. New superluminal wave pulses are first constructed and then tailored so that they become temporally focused at a chosen spatial point, where the wave field can reach very high intensities

Michel Zamboni-Rached; Amr M. Shaarawi; Erasmo Recami

2004-01-01

260

Infra-red radiation focusators  

NASA Astrophysics Data System (ADS)

This paper presents the results of investigations in the field of diffractive or 'binary' computer-generated optics for the infrared region of the spectrum. The problem of a CO2-laser beam focusing into a complicated focal domain is considered in detail. Special ray-tracing methods are elaborated to calculate the new analytic functions of diffractive optical elements, called focusators. The development of IR focusators into a ring, uniform planar spots, segments of a straight line, and other focal domains for the CO2 lasers powered from several watts up to 3 kW is reported. Reflective-type focusators are manufactured by a specific microrelief technology that has some features in common with normal microelectronic technology. Experimental results for focused-beam interaction with rubber, wood, fabric, and plastics are presented for the case of a 30-W laser. Effective laser heat-hardening of steel is achieved by 3-kW CO2 laser by means of a computer-generated reflective focusator.

Golub, M. A.; Sisakian, I. N.; Soifer, V. A.

261

AXAF SIM focus mechanism study  

NASA Technical Reports Server (NTRS)

The design requirements and initial design concept for the AXAF-I Science Instrument Module (SIM) were reviewed at Ball on September 29, 1993. The concept design SIM focus mechanism utilizes a planetary gearset, with redundant motors, to drive a large ring (called 'main housing bearing') via a spur gearset. This large drive ring actuates three tangent bar links (called 'push rods'), which in turn actuate three levers (called 'pin levers'). Each of the three pin levers rotates an 'eccentric pin,' which in turn moves the base of a bipod flexure in both the radial (normal to optical axis) and axial (focus along optical axis) directions. Three bipod flexures are employed, equally spaced at 120 degrees apart, the base of each being translated in the two directions as described above. A focus adjustment is made by rotating the drive ring, which drives the push rods and therefore the pin levers, which in turn rotate the eccentric pins, finally imparting the two motions to the base of each of the bipod flexures. The axial translation (focus adjustment) of the focused structure is the sum of the direct axial motion plus axial motion which comes from uniformly squeezing the three bipod bases radially inward. SAO documented the following concerns regarding the focus mechanism in memo WAP-FY94-001, dated October 7, 1993: (1) The focus adjustment depends, in large part, on the structural properties (stiffnesses and end fixities) of the bipod flexures, push rods, pin levers and eccentric pins. If these properties are not matched very well, then lateral translations as well as unwanted rotations of the focussed structure will accompany focus motion. In addition, the stackup of linkage tolerances and any nonuniform wear in the linkages will result in the same unwanted motions. Thermal gradients will also affect these motions. At the review Ball did not present supporting analyses to support their choice of this design concept. (2) The proposed 'primary' method of measuring focus is by counting motor steps. The 'backup' method is by a pot mounted on the drive ring. Neither method provides for a direct measurement of the quantity desired (focus position). This is of concern because of the long and indirect relationship between focus and the sensed quantity (drive ring rotation). There are three sinusoidal relationships and structural stiffness in the path, and the resulting calibration is likely to be highly nonlinear. These methods would require an accurate ground calibration. (3) Ground calibration (and verification) of focus vs. drive position must be done in 1-g on the ground. This calibration will be complicated by both the structural characteristics of the bipods and the fact that the CG of the translating portion of the SIM is not on the optical axis (thereby causing unwated rotations and changing the focus position vs. motor step and pot readout relationships). The SIM translating weight could be offloaded, but the calibration then becomes sensitive to any errors in offloading (both magnitude and direction). There are concerns as to whether a calibration to the required accuracy can be accomplished on the ground. (4) The choice of a potentiometer as the focus position sensor is questionable in terms of reliability for a five year mission. The results of SAO's study of items 1, 2 and 3 described above are presented in this report.

Tananbaum, H. D.; Whitbeck, E.

1994-01-01

262

Focus cues affect perceived depth  

PubMed Central

Depth information from focus cues—accommodation and the gradient of retinal blur—is typically incorrect in three-dimensional (3-D) displays because the light comes from a planar display surface. If the visual system incorporates information from focus cues into its calculation of 3-D scene parameters, this could cause distortions in perceived depth even when the 2-D retinal images are geometrically correct. In Experiment 1 we measured the direct contribution of focus cues to perceived slant by varying independently the physical slant of the display surface and the slant of a simulated surface specified by binocular disparity (binocular viewing) or perspective/texture (monocular viewing). In the binocular condition, slant estimates were unaffected by display slant. In the monocular condition, display slant had a systematic effect on slant estimates. Estimates were consistent with a weighted average of slant from focus cues and slant from disparity/texture, where the cue weights are determined by the reliability of each cue. In Experiment 2, we examined whether focus cues also have an indirect effect on perceived slant via the distance estimate used in disparity scaling. We varied independently the simulated distance and the focal distance to a disparity-defined 3-D stimulus. Perceived slant was systematically affected by changes in focal distance. Accordingly, depth constancy (with respect to simulated distance) was significantly reduced when focal distance was held constant compared to when it varied appropriately with the simulated distance to the stimulus. The results of both experiments show that focus cues can contribute to estimates of 3-D scene parameters. Inappropriate focus cues in typical 3-D displays may therefore contribute to distortions in perceived space.

Watt, Simon J.; Akeley, Kurt; Ernst, Marc O.; Banks, Martin S.

2007-01-01

263

Ultrasound-induced acoustophoretic motion of microparticles in three dimensions.  

PubMed

We derive analytical expressions for the three-dimensional (3D) acoustophoretic motion of spherical microparticles in rectangular microchannels. The motion is generated by the acoustic radiation force and the acoustic streaming-induced drag force. In contrast to the classical theory of Rayleigh streaming in shallow, infinite, parallel-plate channels, our theory does include the effect of the microchannel side walls. The resulting predictions agree well with numerics and experimental measurements of the acoustophoretic motion of polystyrene spheres with nominal diameters of 0.537 and 5.33 ?m. The 3D particle motion was recorded using astigmatism particle tracking velocimetry under controlled thermal and acoustic conditions in a long, straight, rectangular microchannel actuated in one of its transverse standing ultrasound-wave resonance modes with one or two half-wavelengths. The acoustic energy density is calibrated in situ based on measurements of the radiation dominated motion of large 5-?m-diameter particles, allowing for quantitative comparison between theoretical predictions and measurements of the streaming-induced motion of small 0.5-?m-diameter particles. PMID:24032923

Muller, P B; Rossi, M; Marín, A G; Barnkob, R; Augustsson, P; Laurell, T; Kähler, C J; Bruus, H

2013-08-01

264

Understanding ultrasound induced sonoporation: definitions and underlying mechanisms.  

PubMed

In the past two decades, research has underlined the potential of ultrasound and microbubbles to enhance drug delivery. However, there is less consensus on the biophysical and biological mechanisms leading to this enhanced delivery. Sonoporation, i.e. the formation of temporary pores in the cell membrane, as well as enhanced endocytosis is reported. Because of the variety of ultrasound settings used and corresponding microbubble behavior, a clear overview is missing. Therefore, in this review, the mechanisms contributing to sonoporation are categorized according to three ultrasound settings: i) low intensity ultrasound leading to stable cavitation of microbubbles, ii) high intensity ultrasound leading to inertial cavitation with microbubble collapse, and iii) ultrasound application in the absence of microbubbles. Using low intensity ultrasound, the endocytotic uptake of several drugs could be stimulated, while short but intense ultrasound pulses can be applied to induce pore formation and the direct cytoplasmic uptake of drugs. Ultrasound intensities may be adapted to create pore sizes correlating with drug size. Small molecules are able to diffuse passively through small pores created by low intensity ultrasound treatment. However, delivery of larger drugs such as nanoparticles and gene complexes, will require higher ultrasound intensities in order to allow direct cytoplasmic entry. PMID:24270006

Lentacker, I; De Cock, I; Deckers, R; De Smedt, S C; Moonen, C T W

2014-06-01

265

An extensive empirical evaluation of focus measures for digital photography  

NASA Astrophysics Data System (ADS)

Automatic focusing of a digital camera in live preview mode, where the camera's display screen is used as a viewfinder, is done through contrast detection. In focusing using contrast detection, a focus measure is used to map an image to a value that represents the degree of focus of the image. Many focus measures have been proposed and evaluated in the literature. However, previous studies on focus measures have either used a small number of benchmarks images in their evaluation, been directed at microscopy and not digital cameras, or have been based on ad hoc evaluation criteria. In this paper, we perform an extensive empirical evaluation of focus measures for digital photography and advocate using three standard statistical measures of performance— precision, recall, and mean absolute error—as evaluation criteria. Our experimental results indicate that (i) some popular focus measures perform poorly when applied to autofocusing in digital photography, and (ii) simple focus measures based on taking the first derivative of an image perform exceedingly well in digital photography.

Mir, Hashim; Xu, Peter; van Beek, Peter

2014-03-01

266

Fast and precise continuous focusing with focus tunable lenses  

NASA Astrophysics Data System (ADS)

Focusing in milliseconds without translational mechanics involved is possible with electrically tunable lenses. Fast shape-changing lenses enable fast imaging systems which can focus at distances from infinity to a few centimeters with a high optical quality. Furthermore, rapid laser processing in three dimensions is realized without mechanical translation of the focusing lens or the sample. With tunable lenses the entire optics can be made compact, robust and abrasion-free. Different configurations are discussed, how to integrate the tunable lens in the optical path. For machine vision applications, the achievable optical quality depends on the chosen combination of the tunable lens with a fixed focal length lens and a camera. It is recommended to use a fixed focus lens with a short distance between the stop position and the front of the lens. Furthermore, important points are presented how to achieve optimal performance in laser processing applications such as orientation and position of the tunable lens and the diameter of the beam incident on the lens. Additionally, different approaches will be discussed for monitoring the focal length of the tunable lens. The focal length of the tunable lens is sensitive to temperature changes, as the lens material is a fluid. However, in contrast to conventional lenses, the focal length of the tunable lens can be corrected electrically. For that purpose, the tunable lens exhibits an integrated temperature sensor for temperature compensation. Also optical feedback solutions will be presented for applications requiring highest precision and tracking of the absolute focal length value.

Casutt, Selina; Bueeler, Michael; Blum, Mark; Aschwanden, Manuel

2014-03-01

267

Magnetically focused liquid drop radiator  

DOEpatents

A magnetically focused liquid drop radiator for application in rejecting rgy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

Botts, Thomas E. (Fairfax, VA) [Fairfax, VA; Powell, James R. (Shoreham, NY) [Shoreham, NY; Lenard, Roger (Redondo Beach, CA) [Redondo Beach, CA

1986-01-01

268

Magnetically focused liquid drop radiator  

DOEpatents

A magnetically focused liquid drop radiator for application in rejecting energy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

Botts, T.E.; Powell, J.R.; Lenard, R.

1984-12-10

269

EUV Focus Sensor: Design and Modeling  

SciTech Connect

We describe performance modeling and design optimization of a prototype EUV focus sensor (FS) designed for use with existing 0.3-NA EUV projection-lithography tools. At 0.3-NA and 13.5-nm wavelength, the depth of focus shrinks to 150 nm increasing the importance of high-sensitivity focal-plane detection tools. The FS is a free-standing Ni grating structure that works in concert with a simple mask pattern of regular lines and spaces at constant pitch. The FS pitch matches that of the image-plane aerial-image intensity: it transmits the light with high efficiency when the grating is aligned with the aerial image laterally and longitudinally. Using a single-element photodetector, to detect the transmitted flux, the FS is scanned laterally and longitudinally so the plane of peak aerial-image contrast can be found. The design under consideration has a fixed image-plane pitch of 80-nm, with aperture widths of 12-40-nm (1-3 wavelengths), and aspect ratios of 2-8. TEMPEST-3D is used to model the light transmission. Careful attention is paid to the annular, partially coherent, unpolarized illumination and to the annular pupil of the Micro-Exposure Tool (MET) optics for which the FS is designed. The system design balances the opposing needs of high sensitivity and high throughput optimizing the signal-to-noise ratio in the measured intensity contrast.

Goldberg, Kenneth A.; Teyssier, Maureen E.; Liddle, J. Alexander

2005-05-01

270

NICMOS Optimum Coronagraphic Focus Determinaton  

NASA Astrophysics Data System (ADS)

As originally designed the NICMOS coronagraph had two focii at conjugate points in the optical path with the coronagraphic hole at the f/24 focus of the input OTA beam, and the detector at the reimaged f/45 focus in Camera 2. Because of the forward displacement of the cold optical bench holding the Camera 2 detector, as a result of the larger-than-expected expansion of the solid N2 cryogen {as described and documented by the 'Dewar Anomoly Review Board'}, the two focii are now aconjugate. For direct imaging this is of little concern, and the HST/NICMOS Camera 2 focus interface is established by co-locating the f/45 image plane on the detector. This is done by de-spacing the relayed focus through a translative motion {with compensating comal tilt correction} of the Pupil Alignment Mechanism {PAM}. The mirror which this mechanism drives is upstream of the field divider mirror upon which the coronagraphic hole resides. Therefore, achieving a "best" focus at the detector results in a "soft" focus {in the f/24 image plane} at the coronagraphic hole. This leads to a wavelength-dependent increase in the diffracted energy in the now-defocused unocculted wings of a PSF from a target placed inside of the coronagraphic hole {as the f/24 image plane will fall behind the surface of the camera 2 field divider mirror} increasing the scattered and diffracted background around the target and lowering the field contrast at the detector image plane. In principal the coronagraphic stray light rejection would be most efficient by minimizing the spot size of an input PSF in the hole. This, however, is traded against a small degree of defocus at the detector. Ultimately, the best coronagraphic performance is achieved where the image contrast between an unocculted target and the residual background from an occulted source {both affected differently by focus and subsequent scattering} is maximized. The purpose of this test is to find the optimum PAM position to maximize the coronagraphic image:background contrast ratio. Further details and background information may be found in the SMOV/7157 test report "NICMOS Optimal Coronagraphic Focus Determination" available from the NICMOS IDT.

Schneider, Glenn

2001-07-01

271

Focusing of pseudoradial polarized beams.  

PubMed

The focusing of a light beam with radial polarization has substantial advantages as the irradiance distribution in the focal plane is symmetric and there is maximum absorption at the focus. Using half wave plates cut into four quadrants with each quadrant having a linear polarization directed outwards gives a total field that approximates radial polarization, called pseudoradial polarization. The irradiance distributions in the focal region for different polarizations and beam profiles are compared. The irradiance is calculated by the numerical integration of the two-dimensional Rayleigh-Sommerfeld diffraction integral of the first kind using the 2DSC method for both circular and annular apertures. PMID:19494972

Cooper, I; Roy, M; Sheppard, C J

2005-02-21

272

Speeding chemical reactions by focusing  

NASA Astrophysics Data System (ADS)

We present numerical results for a chemical reaction of colloidal particles which are transported by a laminar fluid and are focused by periodic obstacles in such a way that the two components are well mixed and consequently the chemical reaction is speeded up. The roles of the various system parameters (diffusion coefficients, reaction rate, and obstacles sizes) are studied. We show that focusing speeds up the reaction from the diffusion limited rate ~t-1/2 to very close to the perfect mixing rate, ~t-1.

Lacasta, A. M.; Ramírez-Piscina, L.; Sancho, J. M.; Lindenberg, K.

2013-04-01

273

Heating in vascular tissue and flow-through tissue phantoms induced by focused ultrasound  

NASA Astrophysics Data System (ADS)

High intensity focused ultrasound (HIFU) can be used to control bleeding, both from individual blood vessels as well as from gross damage to the capillary bed. This process, called acoustic hemostasis, is being studied in the hope that such a method would ultimately provide a lifesaving treatment during the so-called "golden hour", a brief grace period after a severe trauma in which prompt therapy can save the life of an injured person. Thermal effects play a major role in occlusion of small vessels and also appear to contribute to the sealing of punctures in major blood vessels. However, aggressive ultrasound-induced tissue heating can also impact healthy tissue and can lead to deleterious mechanical bioeffects. Moreover, the presence of vascularity can limit one's ability to elevate the temperature of blood vessel walls owing to convective heat transport. In an effort to better understand the heating process in tissues with vascular structure we have developed a numerical simulation that couples models for ultrasound propagation, acoustic streaming, ultrasound heating and blood cooling in Newtonian viscous media. The 3-D simulation allows for the study of complicated biological structures and insonation geometries. We have also undertaken a series of in vitro experiments, in non-uniform flow-through tissue phantoms, designed to provide a ground truth verification of the model predictions. The calculated and measured results were compared over a range of values for insonation pressure, insonation time, and flow rate; we show good agreement between predictions and measurements. We then conducted a series of simulations that address two limiting problems of interest: hemostasis in small and large vessels. We employed realistic human tissue properties and considered more complex geometries. Results show that the heating pattern in and around a blood vessel is different for different vessel sizes, flow rates and for varying beam orientations relative to the flow axis. Complete occlusion and wall-puncture sealing are both possible depending on the exposure conditions. These results concur with prior clinical observations and may prove useful for planning of a more effective procedure in HIFU treatments.

Huang, Jinlan

274

Nuclear fusion - Focus on Tokamak  

Microsoft Academic Search

An overview of nuclear fusion engineering is presented covering: basic fusion technology, magnetic and inertial confinement schemes, fusion fuel, tritium breeding, blankets, tritium containment and disposal, fusion process waste management, power generation costs, environmental impact, and safety. Attention is focused on closed magnetic confinement systems, specifically Tokamak systems. The outlook for pulsed\\/batch or continuous Tokamak operation is assessed. Power supplies

D. Steiner

1977-01-01

275

Work and Family. Special Focus.  

ERIC Educational Resources Information Center

This newsletter issue focuses on issues concerning families with both parents employed outside the home and describes several employer programs designed to help employees balance their work and family life. The newsletter includes the following articles: (1) "Work and Family: 1992"; (2) "Levi Strauss and Co.--A Work/Family Program in Action"; (3)…

Goetz, Kathy, Ed.

1992-01-01

276

Focused X-ray source  

DOEpatents

An intense, relatively inexpensive X-ray source (as compared to a synchrotron emitter) for technological, scientific, and spectroscopic purposes. A conical radiation pattern produced by a single foil or stack of foils is focused by optics to increase the intensity of the radiation at a distance from the conical radiator.

Piestrup, Melvin A. (Woodside, CA); Boyers, David G. (Mountain View, CA); Pincus, Cary I. (Sunnyvale, CA); Maccagno, Pierre (Stanford, CA)

1990-01-01

277

Focused X-ray source  

DOEpatents

Disclosed is an intense, relatively inexpensive X-ray source (as compared to a synchrotron emitter) for technological, scientific, and spectroscopic purposes. A conical radiation pattern produced by a single foil or stack of foils is focused by optics to increase the intensity of the radiation at a distance from the conical radiator. 8 figs.

Piestrup, M.A.; Boyers, D.G.; Pincus, C.I.; Maccagno, P.

1990-08-21

278

ERS Focus On: Educating Boys  

ERIC Educational Resources Information Center

This issue of "Focus On" examines where boys are underachieving and some possible reasons for their under-achievement, including biological and environmental factors. It also offers strategies that teachers can employ in their classrooms in order to address the educational needs of boys. Books in Brief; Web Resources; and Related ERS Resources are…

Clarke, Suzanne

2007-01-01

279

On Task: Focused Literacy Learning.  

ERIC Educational Resources Information Center

This book focuses on learning as a social process. The language of teaching and learning within classroom literacy lessons, and how this language contributes to building a culture of learning, is a key principle that underlies each concept presented in the book. Each of the chapters asks teachers to examine the interactive nature of classroom life…

Edwards-Groves, Christine

280

Focused word segmentation for ASR  

Microsoft Academic Search

We propose a new set of features based on the temporal statistics of the spectral entropy of speech. We show why these features make good inputs for a speech detector. Moreover, we propose a back-end that uses the evidence from the above features in a 'focused' manner. Subsequently, by means of recognition ex- periments we show that using the above

Amarnag Subramanya; Jeff Bilmes; Chia-Ping Chen

2005-01-01

281

Teaching and Learning. IDRA Focus.  

ERIC Educational Resources Information Center

This theme issue includes four articles that focus on teaching and learning strategies to benefit all students, including limited-English-proficient, minority, economically disadvantaged, and at-risk students. "Would You Read Me a Story?: In Search of Reading Strategies That Work for the Early Childhood Classroom" (Hilaria Bauer) discusses how…

IDRA Newsletter, 1997

1997-01-01

282

Developing the Strategically Focused School  

ERIC Educational Resources Information Center

This article builds a conceptual framework to examine how school leaders can move away from a planning framework that emphasizes only short-term target setting and move to an effective strategic approach. It examines early evidence from research on what dimensions are critical in establishing a strategically focused school within a medium-term…

Davies, Brent

2004-01-01

283

Focus Constraints on Language Generation  

Microsoft Academic Search

Computer generation of natural language requires the ability to make reasoned choices from a large number of possible things to say as well as from a large number of expressive possibilities. This paper examines in detail how one influence on a generated text, focus of attention, can be used to constrain the many possibilities that a generation system must consider.

Kathleen Mckeown

1983-01-01

284

LBL neutralized beam focusing experiment  

SciTech Connect

An intense neutralized Cs/sup +1/ beam has been focused by an electrostatic polarization field induced by a solenoidal magnetic field of 10-25 gauss. This report describes the experiment and compares the results with the predictions of an analytic linearized fluid model and a particle-in-cell simulation which treats the motion of the warm electrons in detail.

Krafft, G.A.; Kim, C.H.; Smith, L.

1985-05-01

285

Tsunami Amplification due to Focusing  

NASA Astrophysics Data System (ADS)

Tsunami runup measurements over the periphery of the Pacific Ocean after the devastating Great Japan tsunami of 11 March 2011 showed considerable variation in far-field and near-field impact. This variation of tsunami impact have been attributed to either directivity of the source or by local topographic effects. Directivity arguments alone, however, cannot explain the complexity of the radiated patterns in oceans with trenches and seamounts. Berry (2007, Proc. R. Soc. Lond. A 463, 3055-3071) discovered how such underwater features may concentrate tsunamis into cusped caustics and thus cause large local amplifications at specific focal points. Here, we examine focusing and local amplification, not by considering the effects of underwater diffractive lenses, but by considering the details of the dipole nature of the initial profile, and propose that certain regions of coastline are more at-risk, not simply because of directivity but because typical tsunami deformations create focal regions where abnormal tsunami wave height can be registered (Marchuk and Titov, 1989, Proc. IUGG/IOC International Tsunami Symposium, Novosibirsk, USSR). In this work, we present a new general analytical solution of the linear shallow-water wave equation for the propagation of a finite-crest-length source over a constant depth without any restriction on the initial profile. Unlike the analytical solution of Carrier and Yeh (2005, Comp. Mod. Eng. & Sci. 10(2), 113-121) which was restricted to initial conditions with Gaussian profiles and involved approximation, our solution is not only exact, but also general and allows the use of realistic initial waveform such as N-waves as defined by Tadepalli and Synolakis (1994, Proc. R. Soc. Lond. A 445, 99-112). We then verify our analytical solution for several typical wave profiles, both with the NOAA tsunami forecast model MOST (Titov and Synolakis, 1998, J. Waterw. Port Coast. Ocean Eng. 124(4), 157-171) which is validated and verified through (Synolakis et al., 2008, Pure Appl. Geophys. 165(11-12), 2197-2228), and with a Boussinesq model, to illustrate the role focusing can play for different initial conditions, and to show the robust nature of focusing with respect to dispersion. We also show how the focusing effect might have played a role in the 17 July 1998 Papua New Guinea and 17 July 2006 Java events, and also the 11 March 2011 Great Japan earthquake and tsunami. Our results strongly imply that focusing increases the shoreline amplification of the tsunami.; Schematic of focusing; initial displacement (upper left), wave evolution (upper right, lower left), maximum wave amplitude with focusing (lower right).

Moore, C. W.; Kanoglu, U.; Titov, V. V.; Aydin, B.; Spillane, M. C.; Synolakis, C. E.

2012-12-01

286

FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics  

NASA Astrophysics Data System (ADS)

Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and technology and promote new research and development in this field.

Ohashi, Naoki

2011-06-01

287

Early Detection Research Worldwide  

Cancer.gov

Genetic research on cancer has grown tremendously in the last decade, and the increase in the number of published research articles has been truly phenomenal. However, molecular and genetic research focusing on the early detection of cancer is still lagging.

288

EDITORIAL: Focus on Gravitational Lensing  

NASA Astrophysics Data System (ADS)

Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies or quasars which are strongly magnified and sheared. In the last decade, double and quadruply imaged systems due to galactic lenses have been studied with optical and radio observations. An interesting result obtained from the flux ratio 'anomalies' of quadruply imaged systems is the statistical detection of dark sub-clumps in galaxy halos. More broadly, while we have learned a lot about the mass distribution in lens galaxies and improved time delay constraints on the Hubble constant, the limitations of cosmological studies with strong lensing due to uncertainties in lens mass models have also come to be appreciated. That said, progress will no doubt continue with qualitative advances in observations such as astrometric counterparts to the flux anomalies, clever ideas such as the use of spectroscopic signatures to assemble the SLACS lens sample, and combining optical imaging, spectroscopy and radio data to continue the quest for a set of golden lenses to measure the Hubble constant. Galaxy clusters are a fascinating arena for studying the distribution of dark and baryonic matter. Weak and strong lensing information can be combined with dynamical information from the spectroscopic measurements of member galaxies and x-ray/Sunyaev Zeldovich measurements of the hot ionized gas. Hubble Space Telescope observations have yielded spectacular images of clusters, such as Abell 1689, which has over a hundred multiply imaged arcs. Mass measurements have progressed to the level of 10 percent accuracy for several clusters. Unfortunately, it is unclear if one can do much better for individual clusters given inherent limitations such as unknown projection effects. The statistical study of clusters is likely to remain a promising way to study dark matter, gravity theories, and cosmology. Techniques to combine weak and strong lensing information to obtain the mass distribution of clusters have also advanced, and work continues on parameter-free techniques that are agnostic to the relation of cluster light and mass. An interesting twist in cluster lensing was provided by the pos

Jain, Bhuvnesh

2007-11-01

289

Focusing properties of linear undulators  

NASA Astrophysics Data System (ADS)

This paper investigates the focusing properties of linear magnetic undulators, i.e., devices characterized by weak defocusing properties in the horizontal (wiggling) plane and strongly focusing in the vertical plane. The problem of identifying the conditions that ensure the existence of the electron beam eigenstates in the undulator lattice for a given working point of electron beam energy Eb and resonant wavelength ?r is studied. For any given undulator lattice, a bandlike structure is identified defining regions in the (Eb,?r) plane where no periodic matching condition can be found, i.e., it is not possible to transport the electron beam so that optical functions are periodic at lattice boundaries. Some specific cases are discussed for the SPARC FEL undulator.

Quattromini, M.; Artioli, M.; Di Palma, E.; Petralia, A.; Giannessi, L.

2012-08-01

290

Wolter optics for neutron focusing  

NASA Astrophysics Data System (ADS)

Focusing optics based on Wolter optical geometries developed for X-ray grazing incidence beams can be designed for neutron beams. Wolter optics are formed by grazing incidence reflections from two concentric conic sections (for example, a paraboloid and a hyperboloid). This has transformed observational X-ray astronomy by increasing the sensitivity by many orders of magnitude for research in astrophysics and cosmology. To increase the collection area, many reflecting mirrors of different diameters are nested with a common focal plane. These mirrors are fabricated using nickel-electroformed replication techniques. We apply these ideas to neutron focusing using nickel mirrors. We show an initial test of a conical mirror using a beam of cold neutrons.

Mildner, D. F. R.; Gubarev, M. V.

2011-04-01

291

Dual-focus stereo imaging  

NASA Astrophysics Data System (ADS)

We present a novel stereo imaging technique called dual-focus stereo imaging or DFSI. DFSI uses a pair of images captured from different viewpoints and at different foci, but with identical wide aperture size. Each image in an DFSI pair exhibits different defocus blur, and the two images form a defocused stereo pair. To model defocus blur, we introduce a defocus kernel map (DKM) that computes the size of the blur disk at each pixel. We derive a novel disparity defocus constraint for computing the DKM in DFSI, and integrate DKM estimation with disparity map estimation to simultaneously recover both maps. We show that the recovered DKMs provide useful guidance for segmenting the in-focus regions. We demonstrate using DFSI in a variety of imaging applications, including low-light imaging, automatic defocus matting, and multifocus photomontage.

Li, Feng; Sun, Jian; Wang, Jue; Yu, Jingyi

2010-10-01

292

Ballistic Focusing of Polyenergetic Protons Driven by Petawatt Laser Pulses  

Microsoft Academic Search

By using a thick (250mum) target with 350mum radius of curvature, the intense proton beam driven by a petawatt laser is focused at a distance of ˜1mm from the target for all detectable energies up to ˜25MeV. The thickness of the foil facilitates beam focusing as it suppresses the dynamic evolution of the beam divergence caused by peaked electron flux

S. Kar; K. Markey; M. Borghesi; D. C. Carroll; P. McKenna; D. Neely; M. N. Quinn; M. Zepf

2011-01-01

293

Focused electron beam in pyroelectric electron probe microanalyzer  

SciTech Connect

We report a method to focus the electron beam generated using a pyroelectric crystal. An electron beam with a spot size of 100 ?m was achieved by applying an electrical field to an electroconductive needle tip set on a pyroelectric crystal. When the focused electron beam bombarded a sample, characteristic X-rays of the sample were only detected due to the production of an electric field between the needle tip and the sample.

Imashuku, Susumu; Imanishi, Akira; Kawai, Jun [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)] [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

2013-07-15

294

Focus Issue: Signaling Across Membranes  

NSDL National Science Digital Library

This week’s issues of Science and Science’s STKE focus on movement of molecules and information across cellular membranes. Science highlights the mechanisms by which proteins, ions, and DNA cross the membranes of eukaryotic and prokaryotic cells. STKE addresses how information is transmitted across cell membranes to allow cells to communicate with each other and to respond to signals in their environments.

Nancy R. Gough (American Association for the Advancement of Science;Science's STKE REV)

2005-12-06

295

Focus on phosphoaspartate and phosphoglutamate  

Microsoft Academic Search

Protein phosphorylation is a common signalling mechanism in both prokaryotic and eukaryotic organisms. Whilst the focus of\\u000a protein phosphorylation research has primarily been on protein serine\\/threonine or tyrosine phosphorylation, there are other\\u000a phosphoamino acids that are also biologically important. Two of the phosphoamino acids that are functionally involved in the\\u000a biochemistry of protein phosphorylation and signalling pathways are phosphoaspartate and

P. V. Attwood; P. G. Besant; Matthew J. Piggott

2011-01-01

296

Focused Ultrasound for Tumor Ablation  

Microsoft Academic Search

This chapter reviews the basic principles of focused ultrasound therapy. The physical principles are discussed and explained.\\u000a The technical requirements and instrumentation used are illustrated. The critical value of using magnetic resonance (MR) as\\u000a an image guidance method for planning, delivering, and monitoring this form of ablation therapy is reviewed, and its application\\u000a in uterine leiomyomas is highlighted as an

Clare Tempany; Nathan MacDonold; Elizabeth A. Stewart; Kullervo Hynynen

297

Focused plenoptic camera and rendering  

NASA Astrophysics Data System (ADS)

Plenoptic cameras, constructed with internal microlens arrays, capture both spatial and angular information, i.e., the full 4-D radiance, of a scene. The design of traditional plenoptic cameras assumes that each microlens image is completely defocused with respect to the image created by the main camera lens. As a result, only a single pixel in the final image is rendered from each microlens image, resulting in disappointingly low resolution. A recently developed alternative approach based on the focused plenoptic camera uses the microlens array as an imaging system focused on the image plane of the main camera lens. The flexible spatioangular trade-off that becomes available with this design enables rendering of final images with significantly higher resolution than those from traditional plenoptic cameras. We analyze the focused plenoptic camera in optical phase space and present basic, blended, and depth-based rendering algorithms for producing high-quality, high-resolution images. We also present our graphics-processing-unit-based implementations of these algorithms, which are able to render full screen refocused images in real time.

Georgiev, Todor; Lumsdaine, Andrew

2010-04-01

298

Finite sample effect in temperature gradient focusing.  

PubMed

Temperature gradient focusing (TGF) is a new and promising equilibrium gradient focusing method which can provide high concentration factors for improved detection limits in combination with high-resolution separation. In this technique, temperature-dependent buffer chemistry is employed to generate a gradient in the analyte electrophoretic velocity. By the application of a convective counter-flow, a zero-velocity point is created within a microchannel, at which location the ionic analytes accumulate or focus. In general, the analyte concentration is small when compared with buffer ion concentrations, such that the focusing mechanism works in the ideal, linearized regime. However, this presumption may at times be violated due to significant sample concentration growth or the use of a low-concentration buffer. Under these situations the sample concentration becomes non-negligible and can induce strong nonlinear interactions with buffer ions, which eventually lead to peak shifting and distortion, and the loss of detectability and resolution. In this work we combine theory, simulation, and experimental data to present a detailed study on nonlinear sample-buffer interactions in TGF. One of the key results is the derivation of a generalized Kohlrausch regulating function (KRF) that is valid for systems in which the electrophoretic mobilities are not constant but vary spatially. This generalized KRF greatly facilitates analysis, allowing reduction of the problem to a single equation describing sample concentration evolution, and is applicable to other problems with heterogeneous electrophoretic mobilities. Using this sample evolution equation we have derived an understanding of the nonlinear peak deformation phenomenon observed experimentally in TGF. We have used numerical simulations to validate our theory and to quantitatively predict TGF. Our simulation results demonstrate excellent agreement with experimental data, and also indicate that the proper inclusion of Taylor dispersion is important for the accurate modeling of TGF. This work is an important first step towards the understanding and prediction of the more complex, nonlinear, and multi-species interactions which often occur in on-chip electrophoretic assays such as TGF. PMID:18497919

Lin, Hao; Shackman, Jonathan G; Ross, David

2008-06-01

299

Remote focusing for programmable multi-layer differential multiphoton microscopy  

PubMed Central

We present the application of remote focusing to multiphoton laser scanning microscopy and utilize this technology to demonstrate simultaneous, programmable multi-layer imaging. Remote focusing is used to independently control the axial location of multiple focal planes that can be simultaneously imaged with single element detection. This facilitates volumetric multiphoton imaging in scattering specimens and can be practically scaled to a large number of focal planes. Further, it is demonstrated that the remote focusing control can be synchronized with the lateral scan directions, enabling imaging in orthogonal scan planes.

Hoover, Erich E.; Young, Michael D.; Chandler, Eric V.; Luo, Anding; Field, Jeffrey J.; Sheetz, Kraig E.; Sylvester, Anne W.; Squier, Jeff A.

2010-01-01

300

Probe-pattern grating focus monitor through scatterometry calibration  

NASA Astrophysics Data System (ADS)

This paper presents a new highly sensitive scatterometry based Probe-Pattern Grating (PPG) focus monitor and its printing assessment on an advanced exposure tool. The high sensitivity is achieved by placing transparent lines spaced at the strong focus spillover distance from the centerline of a 90 degree phase-shifted probe line that functions as an interferometer detector. The monitor translates the focus error into the probe line trench depth, which can be measured by scatterometry techniques. The sensitivity of the defocus measurement through scatterometry calibration is around 1.1nm defocus / nm trench depth. This result indicates that the PPG focus monitor from a single wafer focus setting can detect the defocus distance to well under 0.05 Rayleigh Units.

Xue, Jing; Spanos, Costas J.; Neureuther, Andrew R.

2008-04-01

301

Career Pathways: Focus on Biotechnology  

NSDL National Science Digital Library

Career Pathways: Focus on Biotechnology is a students' guide to biotechnology careers in North Carolina. North Carolina has made biotechnology a central part of its economic development strategy and is home to over 350 bioscience companies who offer a wide variety of career opportunities. North Carolina has committed to programs at community colleges and universities that are industry-focused and provide hands-on training for an industry that places enormous value on the scientific and technical training of its employees. To support this industry, we want to assure that potential employees know about the opportunities available in biotechnology and the preparation required in high school and at the community college and university levels to make career choices in this field. Career pathways offer an approach to education that links what happens in the schools with opportunities in the real-world economy. At the high school level, career pathways group careers in related fields and indicate the courses students will need to succeed in any one of the careers. A career pathway is a course of study, focused on subjects related to a particular group of careers, which prepares students for their next steps in education. The North Carolina Department of Public Instruction has made a commitment to support the biotechnology industry. This guide defines the biotechnology industry by grouping related careers, describing the careers, and identifying courses students need in high school to choose careers in their area of interest. By linking education and the world of work, particularly the specific opportunities and workforce needs in biotechnology, schools can target instruction to fit students? needs, inspire students to build their own futures, and help create a workforce that meets the needs of the state economy.

2009-11-24

302

The quest for customer focus.  

PubMed

Companies have poured enormous amounts of money into customer relationship management, but in many cases the investment hasn't really paid off. That's because getting closer to customers isn't about building an information technology system. It's a learning journey-one that unfolds over four stages, requiring people and business units to coordinate in progressively more sophisticated ways. The journey begins with the creation of a companywide repository containing each interaction a customer has with the company, organized not by product, purchase, or location, but by customer. Communal coordination is what's called for at this stage, as each group contributes its information to the data pool separately from the others and then taps into it as needed. In the second stage, one-way serial coordination from centralized IT through analytical units and out to the operating units allows companies to go beyond just assembling data to drawing inferences. In stage three, companies shift their focus from past relationships to future behavior. Through symbiotic coordination, information flows back and forth between central analytic units and various organizational units like marketing, sales, and operations, as together they seek answers to questions like "How can we prevent customers from switching to a competitor?" and "Who would be most likely to buy a new product in the future"? In stage four, firms begin to move past discrete, formal initiatives and, through integral coordination, bring an increasingly sophisticated understanding oftheir customers to bear in all day-to-day operations. Skipping stages denies organizations the sure foundation they need to build a lasting customer-focused mind-set. Those that recognize this will invest their customer relationship dollars much more wisely-and will see their customer-focusing efforts pay offon the bottom line. PMID:15807042

Gulati, Ranjay; Oldroyd, James B

2005-04-01

303

NICMOS Optimum Coronagraphic Focus Determination  

NASA Astrophysics Data System (ADS)

As originally designed the NICMOS coronagraph had two fixed focii in the optical path: {a} at the coronagraphic hole {image plane obscuration} in the camera 2 field divider mirror {at the f/24 focus of the input OTA beam} and, {b} at the detector {reimaged focal plane of the f/45 camera 2 relay optics}. Because of the forward displacement of the cold optical bench holding the Camera 2 detector resulting from the larger-than-expected expansion of the solid N2 cryogen early in HST Cycle 7 {as described and documented by the 'Dewar Anomaly Review Board'}, the two focii are now aconjugate. For direct {non-coronagraphic} imaging, this is of little concern and "best focus" at the detector is readily achieved by adjustment of NICMOS's Pupil Alignment Mechanism mirror. This, however, results in a "soft" focus at the upstream f/24 image plane of the coronagraphic hole and a degradation in coronagraphic contrast. Further deformation and hysteretic displacement of the NICMOS dewar and associated differential stresses on its mounting straps are likely to result from power cycling the NCS during SM4. As a result, the intended locations of the camera 2 focal planes in the cold well at the detector, and in the warm optics outside of the dewar, are likely to change. Such a change was seen following the warmup and cooldown of the NICMOS dewar following cryogen depletion in January 2000 and the installation of the NCS in 2002. If uncompensated, through informed investigation, coronagraphy will be adversely affected since the scattered and diffracted background light from a target afocally imaged in the coronagraphic hole will increase and thus reduce the achievable contrast at the detector image plane. The coronagraphic stray light rejection is most efficient by minimizing the spot size of an input PSF in the coronagraphic hole, but is traded against image defocus at the detector. The purpose of this test is to find the optimum wavelength-dependent compromise in the PAM position to maximize the coronagraphic image:background contrast ratio at the detector. Further details and background information may be found in the SMOV/7157 test report "NICMOS Optimal Coronagraphic Focus Determination" available from the NICMOS IDT. This proposal corresponds to SMOV activity NIC-11.;

Schneider, Glenn

2008-07-01

304

Innovative point focus solar concentrator  

SciTech Connect

Acurex Corporation has a Cooperative Agreement with the United States Department of Energy (DOE) to design, build and test a 15-meter diameter Innovative Point Focus Solar Concentrator. This report presents the results of the Phase I prototype reflective panel optical test. The approach selected for this test was a quick, simple, and relatively inexpensive evaluation of the first outer reflective panel produced. This approach represented a tradeoff between extent of results and test costs. The test measured the focal quality of the panel, and this result was then related to the focal quality of the complete dish assembly.

Not Available

1986-02-01

305

Focus on topological quantum computation  

NASA Astrophysics Data System (ADS)

Topological quantum computation started as a niche area of research aimed at employing particles with exotic statistics, called anyons, for performing quantum computation. Soon it evolved to include a wide variety of disciplines. Advances in the understanding of anyon properties inspired new quantum algorithms and helped in the characterization of topological phases of matter and their experimental realization. The conceptual appeal of topological systems as well as their promise for building fault-tolerant quantum technologies fuelled the fascination in this field. This ‘focus on’ collection brings together several of the latest developments in the field and facilitates the synergy between different approaches.

Pachos, Jiannis K.; Simon, Steven H.

2014-06-01

306

Focus on nonlinear terahertz studies  

NASA Astrophysics Data System (ADS)

Resulting from the availability of improved sources, research in the terahertz (THz) spectral range has increased dramatically over the last decade, leading essentially to the disappearance of the so-called ‘THz gap’. While most work to date has been carried out with THz radiation of low field amplitude, a growing number of experiments are using THz radiation with large electric and magnetic fields that induce nonlinearities in the system under study. This ‘focus on’ collection contains a number of articles, both experimental and theoretical, in the new subfield of THz nonlinear optics and spectroscopy on various systems, among them molecular gases, superconductors, semiconductors, antiferromagnets and graphene.

Leitenstorfer, Alfred; Nelson, Keith A.; Reimann, Klaus; Tanaka, Koichiro

2014-04-01

307

Rotating apparatus for isoelectric focusing  

NASA Technical Reports Server (NTRS)

This disclosure is directed to an isoelectric focusing apparatus, wherein stabilization of the fluid containing the isolated proteins is achieved by carrying out the separation in a rotating cylinder with the separation cavity of the cylinder being segmented by means of filter elements. The filter elements are constituted of a material offering some degree of resistance to fluid convection, but allowing relatively free and unhindered passage of current and transport of proteins. The combined effect of segmentation and rotation has been found to be superior to either segmentation or rotation alone in maintaining the stability of the migrated fractions.

Bier, Milan (Inventor)

1986-01-01

308

Focus Issue: Uncovering Immunological Secrets  

NSDL National Science Digital Library

This Focus Issue of Science’s STKE complements a Special Issue of Science, which features a collection of Perspectives that describe obstacles to attaining a more complete understanding of the immune system. Taking stock of where the field now stands, the authors identify areas that warrant further investigation and speculate on the likely clinical benefits of achieving a deeper understanding of immune function. Articles in Science’s STKE highlight molecular challenges that immunologists have overcome, new questions that have arisen from their studies, and cutting-edge techniques that will enable immunologists to tackle these problems.

John F. Foley (American Association for the Advancement of Science;Associate Editors of Science's STKE REV); Elizabeth M. Adler (American Association for the Advancement of Science;Associate Editors of Science's STKE REV)

2007-08-07

309

EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS  

NASA Astrophysics Data System (ADS)

Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping elements of the puzzle, and those which combine them. Scales, assumptions and the conditions used in order to describe a particular single process of interest must be consistent with the conditions in clouds. The papers in this focus issue of New Journal of Physics collectively demonstrate (i) the variation in scientific approaches towards investigating cloud processes, (ii) the various stages of shaping elements of the puzzle, and (iii) some attempts to put the pieces together. These papers present just a small subset of loosely arranged elements in an initial stage of puzzle creation. Addressed by this issue is one of the important problems in our understanding of cloud processes—the interaction between cloud particles and turbulence. There is currently a gap between the cloud physics community and scientists working in wind tunnels, on turbulence theory and particle interactions. This collection is intended to narrow this gap by bringing together work by theoreticians, modelers, laboratory experimentalists and those who measure and observe actual processes in clouds. It forms a collage of contributions showing various approaches to cloud processes including: • theoretical works with possible applications to clouds (Bistagnino and Boffetta, Gustavsson et al), • an attempt to construct a phenomenological description of clouds and rain (Lovejoy and Schertzer), • simplified models designed to parameterize turbulence micro- and macro-effects (Celani et al, Derevyanko et al), • focused theoretical research aimed at particular cloud processes (Ayala et al, parts I and II, Wang et al), • laboratory and modeling studies of complex cloud processes (Malinowski et al). This collage is far from being complete but, hopefully, should give the reader a representative impression of the current state of knowledge in the field. We hope it will be useful to all scientists whose work is inspired by cloud processes. Focus on Cloud Physics Contents The development of ice in a cumulus cloud over southwest England Yahui Huang, Alan M Blyth, Philip R A Brown, Tom W Choularton,

Falkovich, Gregory; Malinowski, Szymon P.

2008-07-01

310

Targeted therapy using nanotechnology: focus on cancer.  

PubMed

Recent advances in nanotechnology and biotechnology have contributed to the development of engineered nanoscale materials as innovative prototypes to be used for biomedical applications and optimized therapy. Due to their unique features, including a large surface area, structural properties, and a long circulation time in blood compared with small molecules, a plethora of nanomaterials has been developed, with the potential to revolutionize the diagnosis and treatment of several diseases, in particular by improving the sensitivity and recognition ability of imaging contrast agents and by selectively directing bioactive agents to biological targets. Focusing on cancer, promising nanoprototypes have been designed to overcome the lack of specificity of conventional chemotherapeutic agents, as well as for early detection of precancerous and malignant lesions. However, several obstacles, including difficulty in achieving the optimal combination of physicochemical parameters for tumor targeting, evading particle clearance mechanisms, and controlling drug release, prevent the translation of nanomedicines into therapy. In spite of this, recent efforts have been focused on developing functionalized nanoparticles for delivery of therapeutic agents to specific molecular targets overexpressed on different cancer cells. In particular, the combination of targeted and controlled-release polymer nanotechnologies has resulted in a new programmable nanotherapeutic formulation of docetaxel, namely BIND-014, which recently entered Phase II clinical testing for patients with solid tumors. BIND-014 has been developed to overcome the limitations facing delivery of nanoparticles to many neoplasms, and represents a validated example of targeted nanosystems with the optimal biophysicochemical properties needed for successful tumor eradication. PMID:24531078

Sanna, Vanna; Pala, Nicolino; Sechi, Mario

2014-01-01

311

Craters detection on lunar  

Microsoft Academic Search

This project focuses on identification of craters in terms of its characteristics and detection of these visual features of the moon to determine a safe landing site for a lunar Lander. Cheng et al. proposed using craters as landmarks for navigation purposes because this geometric model grants a robust detection under different lighting conditions. Moreover, craters appear in enough density

Nur Diyana Kamarudin; Siti Noormiza Makhtar; Hizrin Dayana M. Hidzir

2011-01-01

312

Focusing Telescopes in Nuclear Astrophysics  

NASA Astrophysics Data System (ADS)

This volume is the first of its kind on focusing gamma-ray telescopes. Forty-eight refereed papers provide a comprehensive overview of the scientific potential and technical challenges of this nascent tool for nuclear astrophysics. The book features articles dealing with pivotal technologies such as grazing incident mirrors, multilayer coatings, Laue- and Fresnel-lenses - and even an optic using the curvature of space-time. The volume also presents an overview of detectors matching the ambitious objectives of gamma ray optics, and facilities for operating such systems on the ground and in space. The extraordinary scientific potential of focusing gamma-ray telescopes for the study of the most powerful sources and the most violent events in the Universe is emphasized in a series of introductory articles. Practicing professionals, and students interested in experimental high-energy astrophysics, will find this book a useful reference Link: http://www.springer.com/east/home/generic/search/results?SGWID=5-40109-22-173670274-0

von Ballmoos, Peter

2006-12-01

313

Micron-focused ion beamlets  

SciTech Connect

A multiple beam electrode system (MBES) is used to provide focused ion beamlets of elements from a compact microwave plasma. In this study, a honeycomb patterned plasma electrode with micron size apertures for extracting ion beamlets is investigated. The performance of the MBES is evaluated with the help of two widely adopted and commercially available beam simulation tools, AXCEL-INP and SIMION, where the input parameters are obtained from our experiments. A simple theoretical model based upon electrostatic ray optics is employed to compare the results of the simulations. It is found that the results for the beam focal length agree reasonably well. Different geometries are used to optimize the beam spot size and a beam spot {approx}5-10 {mu}m is obtained. The multiple ion beamlets will be used to produce microfunctional surfaces on soft matter like polymers. Additionally, the experimental set-up and plans are presented in the light of above applications.

Chowdhury, Abhishek; Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

2010-05-15

314

Focus on integrated quantum optics  

NASA Astrophysics Data System (ADS)

A key goal of research into quantum information processing is the development of technologies that are scaleable in complexity while allowing the mass manufacture of devices that promise transformative effects on information science. The demonstration that integrated photonics circuits could be made to perform operations that exploit the quantum nature of the photon has turned them into leading candidates for practical quantum information processing technologies. To fully achieve their promise, however, requires research from diverse fields. This focus issue provides a snapshot of some of the areas in which key advances have been made. We are grateful for the contributions from leading teams based around the globe and hope that the degree of progress being made in a challenging and exciting field is apparent from the papers published here.

O'Brien, Jeremy; Patton, Brian; Sasaki, Masahide; Vu?kovi?, Jelena

2013-03-01

315

Focus on Basal Cell Carcinoma  

PubMed Central

Nonmelanoma skin cancers (NMSCs), which include basal and squamous cell cancers are the most common human cancers. BCCs have a relatively low metastatic rate and slow growth and are frequently underreported. Whilst there is a definite role of sunexposure in the pathogenesis of BCC, several additional complex genotypic, phenotypic and environmental factors are contributory. The high prevalence and the frequent occurrence of multiple primary BCC in affected individuals make them an important public health problem. This has led to a substantial increase in search for newer noninvasive treatments for BCC. Surgical excision with predetermined margins remains the mainstay treatment for most BCC. Of the newer non-invasive treatments only photodynamic therapy and topical imiquimod have become established in the treatment of certain BCC subtypes, while the search for other more effective and tissue salvaging therapies continues. This paper focuses on the pathogenesis and management of BCC.

Samarasinghe, Venura; Madan, Vishal; Lear, John T.

2011-01-01

316

Non-focusing active warhead  

DOEpatents

A non-nuclear, non-focusing, active warhead that comprises a high explosive charge contained within a casing of reactive metal is disclosed. When the high explosive is detonated, the reactive metal is dispersed and reacts with the air, which significantly increases the explosive yield of the warhead. The active warhead produces therefore much higher blast effects with significantly reduced weight compared to conventional munitions. The warhead is highly effective against such targets as aircraft which typically have thin fuselages, for example. The explosiveness of this warhead can be enhanced further by elevating the temperature and therefore the reactivity of the reactive metal before or during the explosion. New methods of enhancing the reactivity of the metal are also taught. 4 figs.

Hornig, H.C.

1998-12-22

317

Rotating Apparatus for Isoelectric Focusing  

NASA Technical Reports Server (NTRS)

Remixing of separated fractions prevented. Improved isoelectric focusing apparatus helps to prevent electro-osmosis and convection, both of which cause remixing of separated fractions. Fractionating column segmented and rotated about horizontal axis: Only combined effects of both features fully effective in making good separations. Improved apparatus slowly rotated continuously or rocked (at rotational amplitude of at least 180 degrees) about its horizontal axis so average gravitational vector experienced by fluid is zero and convection is therefore suppressed. Electro-osmosis suppressed and convection further suppressed by separating column into disklike compartments along its length with filters. Experiments have shown dimensions of apparatus not critical. Typical compartment and column volumes are 2 and 40 ml, respectively. Rotation speeds lie between 3 and 30 rpm.

Bier, M.

1986-01-01

318

Clinical focus: infections in pregnancy.  

PubMed

Pregnant women are particularly susceptible to a number of infectious diseases, such as influenza, hepatitis E, malaria, and tuberculosis. The management of many other infections-including urinary tract infections, human immunodeficiency virus, and sexually transmitted diseases-is also made more complex by pregnancy; even if some infections do not pose a great risk to the expectant mother, they can impact fetal and neonatal development, thus posing a treatment challenge to physicians. By focusing on the most important diseases that physicians may encounter in pregnant patients, this review outlines the challenges associated with managing important infectious diseases in the pregnant population and references the most recent evidence and international treatment guidelines. PMID:24769790

Adler, Hugh; Lambert, John S

2014-04-01

319

ESPERE Project: Focus on Agronomy  

NASA Astrophysics Data System (ADS)

ESPERE (Environmental Science Published for Everybody Round the Earth) aims to bring the current scientific knowledge of the climate system and its impacts to schools. The Spanish partner (IAMZ) is responsible for: (1) delivering peer-reviewed, reliable information on the impacts, vulnerability and adaptation of agriculture to climate; (2) promoting the interactive cooperation among scientists and non-scientists in the Spanish Educational System; and (3) working in the Spanish language; and (4) revising the content of the other focus areas for their adequacy in the education system of Spain. The presentation will discuss the approach taken in each of the four actions of IAMZ based on past experience and results, present the progress on cooperation with a Pilot School District, and provide the documents produced in Spanish as initial stages of capacity building and outreach.

de La Osa, J.; Iglesias, A.

2003-04-01

320

Tank Focus Area pretreatment activities  

SciTech Connect

Plans call for the high-level wastes to be retrieved from the tanks and immobilized in a stable waste form suitable for long-term isolation. Chemistry and chemical engineering operations are required to retrieve the wastes, to condition the wastes for subsequent steps, and to reduce the costs of the waste management enterprise. Pretreatment includes those processes between retrieval and immobilization, and includes preparation of suitable feed material for immobilization and separations to partition the waste into streams that yield lower life-cycle costs. Some of the technologies being developed by the Tank Focus Area (TFA) to process these wastes are described. These technologies fall roughly into three areas: (1) solid/liquid separation (SLS), (2) sludge pretreatment, and (3) supernate pretreatment.

McGinnis, C.P.; Welch, T.D. [Oak Ridge National Lab., TN (United States); Manke, K.L. [Pacific Northwest National Lab., Richland, WA (United States)

1997-03-01

321

Focused rigidity casts: an overview.  

PubMed

Focused rigidity casts (FRCs) are a novel treatment made from polymer semi-flexible cast material, used in the management of plantar foot ulceration to offload the site of ulceration. Current anecdotal evidence suggests that use of FRCs helps achieve quicker healing time. While FRCs were first used in the treatment of fractures, previous reports suggest that the FRC may be effective in the treatment of plantar foot ulceration. Although there is a paucity of evidence to support the use of FRCs in the treatment of foot ulceration, current evidence demonstrates a decrease in both wound healing time and plantar pressure. The aim of the paper is to examine the importance of offloading plantar ulcerations and introduce FRCs. PMID:23665658

Dagg, A R; Chockalingam, N; Branthwaite, H

2013-02-01

322

Micron-focused ion beamlets  

NASA Astrophysics Data System (ADS)

A multiple beam electrode system (MBES) is used to provide focused ion beamlets of elements from a compact microwave plasma. In this study, a honeycomb patterned plasma electrode with micron size apertures for extracting ion beamlets is investigated. The performance of the MBES is evaluated with the help of two widely adopted and commercially available beam simulation tools, AXCEL-INP and SIMION, where the input parameters are obtained from our experiments. A simple theoretical model based upon electrostatic ray optics is employed to compare the results of the simulations. It is found that the results for the beam focal length agree reasonably well. Different geometries are used to optimize the beam spot size and a beam spot ~5-10 ?m is obtained. The multiple ion beamlets will be used to produce microfunctional surfaces on soft matter like polymers. Additionally, the experimental set-up and plans are presented in the light of above applications.

Chowdhury, Abhishek; Bhattacharjee, Sudeep

2010-05-01

323

Spatially resolved light scattering diagnostic on plasma focus devices  

Microsoft Academic Search

Three Mather-type focus devices with capacitor bank energies of 280, 250 and 12 kJ, respectively, have been studied by collective scattering of ruby laser light. In order to determine the thermal plasma parameters and detect the occurrence of suprathermal scattering from plasma turbulences, the frequency and wavevector spectra of the ion feature of scattered light have been measured. All scattering

G. Bockle; J. Ehrhardt; P. Kirschesch; N. Wenzel; R. Batzner; H. Hinsch; K. Hubner

1992-01-01

324

SWCX Emission from the Helium Focusing Cone - Preliminary Results.  

National Technical Information Service (NTIS)

Preliminary results from an XMM-Newton campaign to study solar wind charge exchange (SWCX) emission from the heliospheric focusing cone of interstellar helium are presented. The detections of enhanced O VII and O VIII emission from the cone are at the 2(s...

K. D. Kuntz M. R. Collier S. L. Snowden

2008-01-01

325

The focus of working capital management in UK small firms  

Microsoft Academic Search

Working capital management routines of a large random sample of small companies in the UK are examined. Considerable variability in the take-up of 11 working capital management routines was detected. Principal components analysis and cluster analysis confirm the identification of four distinct ‘types’ of companies with regard to patterns of working capital management. The first three ‘types’ of companies focused

Carole Howorth; Paul Westhead

2003-01-01

326

Initial results from the Wisconsin spherically convergent ion focus experiment  

Microsoft Academic Search

Summary form only given. The spherically convergent ion focus (SCIF) is an alternative plasma confinement scheme in which ions are electrostatically confined, accelerated, and concentrated at fusion-relevant energies. This concept has been recently promoted for various near-term applications including waste disposal, particle production, neutron radiography and tomography, plastic explosive detection, materials research, and medical isotope production. The Wisconsin SCIF experiments

T. A. Thorson; R. D. Durst; R. J. Fonck; B. S. Foucher; L. P. Wainwright

1995-01-01

327

Focus Issue: A Sharp Focus on Cell Signaling  

NSDL National Science Digital Library

Among the techniques used to study signal transduction, imaging and microscopy have the undeniable appeal of allowing the experimentalist to see cellular structures and--with the advent of new techniques in live-cell light microscopy--to visualize dynamic interactions among molecules in cell signaling pathways. This week's Science and Science's STKE collate material on imaging techniques in cell biology to bring this dynamic area into a sharp focus. Two Reviews in Science provide fundamental information on live-cell imaging. In an overview of live-cell imaging techniques, Stephens and Allan provide advice for researchers considering fluorescence microscopy and discuss such approaches as total internal reflection fluorescence microscopy (TIRFM), fluorescence resonance energy transfer (FRET), and photobleaching and photoactivation. In a complementary Review, Lippincott-Schwartz and Patterson trace the development and applications of green fluorescent protein (GFP) and its variants, which can be used to create chimeric proteins that can be expressed in cells and used to monitor protein localization and protein-protein interactions.

Elizabeth M. Adler (American Association for the Advancement of Science;Associate Editor of Science's STKE REV); Lisa D. Chong (American Association for the Advancement of Science;Associate Editor of Science's STKE and Associate Editor of Science REV); Nancy R. Gough (American Association for the Advancement of Science;Managing Editor of Science's STKE REV)

2003-04-08

328

MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 20  

NASA Astrophysics Data System (ADS)

Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.;

Holland, Stephen

2011-07-01

329

MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 21  

NASA Astrophysics Data System (ADS)

Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.;

Sana, Hugues

2012-07-01

330

MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 19  

NASA Astrophysics Data System (ADS)

Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

Bostroem, Azalee

2010-07-01

331

MAMA Spectroscopic Sensitivity and Focus Monitor Cycle 18  

NASA Astrophysics Data System (ADS)

Monitor sensitivity of each MAMA grating mode to detect any change due tocontamination or other causes. Also monitor the STIS focus in a spectroscopic and animaging mode.Obtain exposures in each of the 2 low-resolution MAMA spectroscopic modes every 4 months, in each of the 2 medium-resolution modes once a year, and in each of the 4 echelle modes every 3 months,using unique calibration standards for each mode, and ratio the results to the firstobservations to detect any trends. In addition, each L-mode sequence will be preceded by twospectroscopic ACQ/PEAKs with the CCD/G230LB and crossed linear patterns, with the purpose of measuringthe focus {PSF across the dispersion as a function of UV wavelength}; and each M-mode sequence will be preceded by aCCD/F28X50OII direct image also to monitor the focus.Whenever possible, obtain parallel airglow spectra with COS.

Osten, Rachel

2009-07-01

332

Focus on quantum Einstein gravity Focus on quantum Einstein gravity  

NASA Astrophysics Data System (ADS)

The gravitational asymptotic safety program summarizes the attempts to construct a consistent and predictive quantum theory of gravity within Wilson's generalized framework of renormalization. Its key ingredient is a non-Gaussian fixed point of the renormalization group flow which controls the behavior of the theory at trans-Planckian energies and renders gravity safe from unphysical divergences. Provided that the fixed point comes with a finite number of ultraviolet-attractive (relevant) directions, this construction gives rise to a consistent quantum field theory which is as predictive as an ordinary, perturbatively renormalizable one. This opens up the exciting possibility of establishing quantum Einstein gravity as a fundamental theory of gravity, without introducing supersymmetry or extra dimensions, and solely based on quantization techniques that are known to work well for the other fundamental forces of nature. While the idea of gravity being asymptotically safe was proposed by Steven Weinberg more than 30 years ago [1], the technical tools for investigating this scenario only emerged during the last decade. Here a key role is played by the exact functional renormalization group equation for gravity, which allows the construction of non-perturbative approximate solutions for the RG-flow of the gravitational couplings. Most remarkably, all solutions constructed to date exhibit a suitable non-Gaussian fixed point, lending strong support to the asymptotic safety conjecture. Moreover, the functional renormalization group also provides indications that the central idea of a non-Gaussian fixed point providing a safe ultraviolet completion also carries over to more realistic scenarios where gravity is coupled to a suitable matter sector like the standard model. These theoretical successes also triggered a wealth of studies focusing on the consequences of asymptotic safety in a wide range of phenomenological applications covering the physics of black holes, early time cosmology and the big bang, as well as TeV-scale gravity models testable at the Large Hadron Collider. On different grounds, Monte-Carlo studies of the gravitational partition function based on the discrete causal dynamical triangulations approach provide an a priori independent avenue towards unveiling the non-perturbative features of gravity. As a highlight, detailed simulations established that the phase diagram underlying causal dynamical triangulations contains a phase where the triangulations naturally give rise to four-dimensional, macroscopic universes. Moreover, there are indications for a second-order phase transition that naturally forms the discrete analog of the non-Gaussian fixed point seen in the continuum computations. Thus there is a good chance that the discrete and continuum computations will converge to the same fundamental physics. This focus issue collects a series of papers that outline the current frontiers of the gravitational asymptotic safety program. We hope that readers get an impression of the depth and variety of this research area as well as our excitement about the new and ongoing developments. References [1] Weinberg S 1979 General Relativity, an Einstein Centenary Survey ed S W Hawking and W Israel (Cambridge: Cambridge University Press)

Ambjorn, Jan; Reuter, Martin; Saueressig, Frank

2012-09-01

333

EDITORIAL: Focus on Attosecond Physics  

NASA Astrophysics Data System (ADS)

Investigations of light matter interactions and motion in the microcosm have entered a new temporal regime, the regime of attosecond physics. It is a main 'spin-off' of strong field (i.e., intense laser) physics, in which nonperturbative effects are fundamental. Attosecond pulses open up new avenues for time-domain studies of multi-electron dynamics in atoms, molecules, plasmas, and solids on their natural, quantum mechanical time scale and at dimensions shorter than molecular and even atomic scales. These capabilities promise a revolution in our microscopic knowledge and understanding of matter. The recent development of intense, phase-stabilized femtosecond (10-15 s) lasers has allowed unparalleled temporal control of electrons from ionizing atoms, permitting for the first time the generation and measurement of isolated light pulses as well as trains of pulses on the attosecond (1 as = 10-18 s) time scale, the natural time scale of the electron itself (e.g., the orbital period of an electron in the ground state of the H atom is 152 as). This development is facilitating (and even catalyzing) a new class of ultrashort time domain studies in photobiology, photochemistry, and photophysics. These new coherent, sub-fs pulses carried at frequencies in the extreme ultraviolet and soft-x-ray spectral regions, along with their intense, synchronized near-infrared driver waveforms and novel metrology based on sub-fs control of electron light interactions, are spawning the new science of attosecond physics, whose aims are to monitor, to visualize, and, ultimately, to control electrons on their own time and spatial scales, i.e., the attosecond time scale and the sub-nanometre (Ångstrom) spatial scale typical of atoms and molecules. Additional goals for experiment are to advance the enabling technologies for producing attosecond pulses at higher intensities and shorter durations. According to theoretical predictions, novel methods for intense attosecond pulse generation may in future involve using overdense plasmas. Electronic processes on sub-atomic spatio-temporal scales are the basis of chemical physics, atomic, molecular, and optical physics, materials science, and even some life science processes. Research in these areas using the new attosecond tools will advance together with the ability to control electrons themselves. Indeed, we expect that developments will advance in a way that is similar to advances that have occurred on the femtosecond time scale, in which much previous experimental and theoretical work on the interaction of coherent light sources has led to the development of means for 'coherent control' of nuclear motion in molecules. This focus issue of New Journal of Physics is centered on experimental and theoretical advances in the development of new methodologies and tools for electron control on the attosecond time scale. Topics such as the efficient generation of harmonics; the generation of attosecond pulses, including those having only a few cycles and those produced from overdense plasmas; the description of various nonlinear, nonperturbative laser matter interactions, including many-electron effects and few-cycle pulse effects; the analysis of ultrashort propagation effects in atomic and molecular media; and the development of inversion methods for electron tomography, as well as many other topics, are addressed in the current focus issue dedicated to the new field of 'Attosecond Physics'. Focus on Attosecond Physics Contents Observing the attosecond dynamics of nuclear wavepackets in molecules by using high harmonic generation in mixed gases Tsuneto Kanai, Eiji J Takahashi, Yasuo Nabekawa and Katsumi Midorikawa Core-polarization effects in molecular high harmonic generation G Jordan and A Scrinzi Interferometric autocorrelation of an attosecond pulse train calculated using feasible formulae Y Nabekawa and K Midorikawa Attosecond pulse generation from aligned molecules—dynamics and propagation in H2+ E Lorin, S Chelkowski and A D Bandrauk Broadband generation in a Raman crystal driven by a pair of time-de

Bandrauk, André D.; Krausz, Ferenc; Starace, Anthony F.

2008-02-01

334

Knowledge focus via software agents  

NASA Astrophysics Data System (ADS)

The essence of military Command and Control (C2) is making knowledge intensive decisions in a limited amount of time using uncertain, incorrect, or outdated information. It is essential to provide tools to decision-makers that provide: * Management of friendly forces by treating the "friendly resources as a system". * Rapid assessment of effects of military actions againt the "enemy as a system". * Assessment of how an enemy should, can, and could react to friendly military activities. Software agents in the form of mission agents, target agents, maintenance agents, and logistics agents can meet this information challenge. The role of each agent is to know all the details about its assigned mission, target, maintenance, or logistics entity. The Mission Agent would fight for mission resources based on the mission priority and analyze the effect that a proposed mission's results would have on the enemy. The Target Agent (TA) communicates with other targets to determine its role in the system of targets. A system of TAs would be able to inform a planner or analyst of the status of a system of targets, the effect of that status, adn the effect of attacks on that system. The system of TAs would also be able to analyze possible enemy reactions to attack by determining ways to minimize the effect of attack, such as rerouting traffic or using deception. The Maintenance Agent would scheudle maintenance events and notify the maintenance unit. The Logistics Agent would manage shipment and delivery of supplies to maintain appropriate levels of weapons, fuel and spare parts. The central idea underlying this case of software agents is knowledge focus. Software agents are createad automatically to focus their attention on individual real-world entities (e.g., missions, targets) and view the world from that entities perspective. The agent autonomously monitors the entity, identifies problems/opportunities, formulates solutions, and informs the decision-maker. The agent must be able to communicate to receive and disseminate information and provide the decision-maker with assistance via focused knowledge. THe agent must also be able to monitor the state of its own environment and make decisions necessary to carry out its delegated tasks. Agents bring three elements to the C2 domain that offer to improve decision-making. First, they provide higher-quality feedback and provide it more often. In doing so, the feedback loop becomes nearly continuous, reducing or eliminating delays in situation updates to decision-makers. Working with the most current information possible improves the control process, thus enabling effects based operations. Second, the agents accept delegation of actions and perform those actions following an established process. Agents' consistent actions reduce the variability of human input and stabilize the control process. Third, through the delegation of actions, agents ensure 100 percent consideration of plan details.

Henager, Donald E.

2001-09-01

335

Aerosol beam-focus laser-induced plasma spectrometer device  

DOEpatents

An apparatus for detecting elements in an aerosol includes an aerosol beam focuser for concentrating aerosol into an aerosol beam; a laser for directing a laser beam into the aerosol beam to form a plasma; a detection device that detects a wavelength of a light emission caused by the formation of the plasma. The detection device can be a spectrometer having at least one grating and a gated intensified charge-coupled device. The apparatus may also include a processor that correlates the wavelength of the light emission caused by the formation of the plasma with an identity of an element that corresponds to the wavelength. Furthermore, the apparatus can also include an aerosol generator for forming an aerosol beam from bulk materials. A method for detecting elements in an aerosol is also disclosed.

Cheng, Meng-Dawn (Oak Ridge, TN) [Oak Ridge, TN

2002-01-01

336

Neutron focusing using capillary optics  

NASA Astrophysics Data System (ADS)

Using the principle of multiple mirror reflection from smooth surfaces at small grazing angles, polycapillary fibers of narrow inner channels (diameter of a few micrometers) have been used to transport and bend slow neutron beams. Neutrons in the cold and thermal range have been focused to a small spot to produce significant gains ( ~ × 10) in intensity. We report studies of neutron transmission properties of individual capillaries, using cold and thermal neutrons at the CNRF (Cold Neutron Research Facility) of the NBSR (the 20 MW research reactor at the National Institute of Standards and Technology, USA). Several aspects of these properties are investigated, namely, the transmission as a function of bending curvature, of length of the fibers, and of composition of fiber materials. From these studies we obtain information on the critical angle of reflection, the reflectivity, and the roughness of the inner surface. We also report the characterization of the first prototype neutron lens constructed at the Kurchatov Institute in Moscow and show that a focal point of 1 mm has been achieved. Finally we discuss the design of a lens suitable for neutron absorption experiments at the end of a neutron guide.

Chen, H.; Mildner, D. F. R.; Downing, R. G.; Benenson, R. E.; Xiao, Q. F.; Sharov, V. A.

1994-05-01

337

Findings: LANL outsourcing focus groups  

SciTech Connect

In March 1996, a series of 24 3-hour dialog focus groups were held with randomly selected Laboratory employees and contractors to gain their perceptions regarding potentials and problems for privatization and consolidation. A secondary goal was to educate and inform the workforce about potentials and issues in privatization and consolidation. Two hundred and thirty-six participants engaged in a learning session and structured input exercises resulting in 2,768 usable comments. Comments were categorized using standard qualitative methods; resulting categories included positive and negative comments on four models (consolidation, spin offs, outsourcing, and corporate partnering) and implications for the workforce, the Laboratory, and the local economy. Categories were in the areas of increasing/decreasing jobs, expertise, opportunity/salary/benefits, quality/efficiency, and effect on the local area and economy. An additional concern was losing Laboratory culture and history. Data were gathered and categorized on employee opinion regarding elements of successful transition to the four models, and issues emerged in the areas of terms and conditions of employment; communication; involvement; sound business planning; ethics and fairness; community infrastructure. From the aggregated opinion of the participants, it is recommended that decision-makers: Plan using sound business principles and continually communicate plans to the workforce; Respect workforce investments in the Laboratory; Tell the workforce exactly what is going on at all times; Understand that economic growth in Northern New Mexico is not universally viewed as positive; and Establish dialog with stakeholders on growth issues.

Jannotta, M.J.; McCabe, V.B.

1996-12-31

338

Ballistic Focusing of Polyenergetic Protons Driven by Petawatt Laser Pulses  

SciTech Connect

By using a thick (250 {mu}m) target with 350 {mu}m radius of curvature, the intense proton beam driven by a petawatt laser is focused at a distance of {approx}1 mm from the target for all detectable energies up to {approx}25 MeV. The thickness of the foil facilitates beam focusing as it suppresses the dynamic evolution of the beam divergence caused by peaked electron flux distribution at the target rear side. In addition, reduction in inherent beam divergence due to the target thickness relaxes the curvature requirement for short-range focusing. Energy resolved mapping of the proton beam trajectories from mesh radiographs infers the focusing and the data agree with a simple geometrical modeling based on ballistic beam propagation.

Kar, S.; Borghesi, M.; Zepf, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, BT7 1NN (United Kingdom); Markey, K. [Centre for Plasma Physics, School of Mathematics and Physics, Queen's University Belfast, BT7 1NN (United Kingdom); Central Laser Facility, Rutherford Appleton Laboratory, OX11 0QX (United Kingdom); Carroll, D. C; McKenna, P.; Quinn, M. N. [SUPA, Department of Physics, University of Strathclyde, Glasgow, G4 0NG (United Kingdom); Neely, D. [Central Laser Facility, Rutherford Appleton Laboratory, OX11 0QX (United Kingdom)

2011-06-03

339

Ballistic focusing of polyenergetic protons driven by petawatt laser pulses.  

PubMed

By using a thick (250???m) target with 350???m radius of curvature, the intense proton beam driven by a petawatt laser is focused at a distance of ?1??mm from the target for all detectable energies up to ?25??MeV. The thickness of the foil facilitates beam focusing as it suppresses the dynamic evolution of the beam divergence caused by peaked electron flux distribution at the target rear side. In addition, reduction in inherent beam divergence due to the target thickness relaxes the curvature requirement for short-range focusing. Energy resolved mapping of the proton beam trajectories from mesh radiographs infers the focusing and the data agree with a simple geometrical modeling based on ballistic beam propagation. PMID:21702607

Kar, S; Markey, K; Borghesi, M; Carroll, D C; McKenna, P; Neely, D; Quinn, M N; Zepf, M

2011-06-01

340

Does Affect Induce Self-Focused Attention?  

Microsoft Academic Search

Despite growing evidence that depression is linked with self-focused attention, little is known about how depressed individuals become self-focused or, more generally, about what arouses self-focus in everyday life. Two experiments examined the hypothesis that affect itself induces self-focused attention. In Experiment 1, moods were manipulated with an imagination mood-induction procedure. Sad-induction Ss became higher in self-focus than did neutral-induction

Joanne V. Wood; Judith A. Saltzberg; Lloyd A. Goldsamt

1990-01-01

341

Regulatory Focus, Transformational Leadership, and Job Satisfaction  

Microsoft Academic Search

Research has suggested people have two distinct hedonic self-regulatory systems, promotion self-regulatory focus and prevention self-regulatory focus. Individuals in promotion focus are sensitive to the presence of gains and positive results. On the other hand, individuals in prevention focus are sensitive to the absence of losses. In this paper we integrate recent theories of regulatory focus and leadership. We propose

Huang Jingjing; Hao Yingqi

2011-01-01

342

EDITORIAL: Focus on Molecular Electronics FOCUS ON MOLECULAR ELECTRONICS  

NASA Astrophysics Data System (ADS)

The notion 'molecular electronics' has been used more frequently since the 1970s and summarizes a series of physical phenomena and ideas for their application in connection with organic molecules, oligomers, polymers, organic aggregates and solids. The properties studied in this field were connected to optical and electrical phenomena, such as optical absorption, fluorescence, nonlinear optics, energy transport, charge transfer, electrical conductance, and electron and nuclear spin-resonance. The final goal was and is to build devices which can compete or surpass some aspects of inorganic semiconductor devices. For example, on the basis of organic molecules there exist rectifiers, transistors, molecular wires, organic light emitting diodes, elements for photovoltaics, and displays. With respect to applications, one aspect of the organic materials is their broad variability and the lower effort and costs for their processability. The step from microstructures to the investigation of nanostructures is a big challenge also in this field and has lead to what nowadays is called molecular electronics in its narrow sense. In this field the subjects of the studies are often single molecules, e.g. single molecule optical spectroscopy, electrical conductance, i.e. charge transport through a single molecule, the influence of vibrational degrees of freedom, etc. A challenge here is to provide the techniques for addressing in a reproducible way the molecular scale. In another approach small molecular ensembles are studied in order to avoid artefacts from particular contact situations. The recent development of the field is presented in [1 8]. In this Focus Issue we present new results in the field of 'molecular electronics', both in its broad and specialized sense. One of the basic questions is the distribution of the energy levels responsible for optical absorption on the one hand and for the transport of charge on the other. A still unanswered question is whether the Wannier exciton model applies in which the excitation is distributed over several molecules or whether a good description is given by the Frenkel exciton model with the electron and the whole being localized at the same molecular unit. In organic semiconductors the charge transport usually occurs on the basis of holes because of the presence of many defects giving rise to a localization of the electrons. It is therefore a challenge to produce materials with both positive and negative mobile charge carriers. In the 1990s V M Agranovich introduced the idea of hybrid excitons, i.e. of nanostructured materials consisting of both organic and inorganic semiconductors. At the interface between the organic and inorganic parts new excitons can appear, being a superposition of both Frenkel and Wannier excitons and having both the high oscillator strength of the Frenkel and the large optical nonlinearity of the Wannier exciton. The problem is to find optimum combinations of the organic and inorganic parts to enable the hybrid structure concept to work. Micro-cavities also play an important role in the investigation of organic materials resulting in a new state (polariton) as the superposition of a photon and an exciton because of the large exciton photon interaction. A similar excitation arises because of the interaction between plasmons and photons. A special geometrical shape of a nano-cavity increases the interaction between the electromagnetic radiation and a dipole sitting in the cavity. The interaction between vibronic degrees of freedom and electronic excitations plays an important role for various phenomena such as nonlinear processes, the question of coherence, information on the shape of a potential hypersurface, etc. With the help of femtosecond laser pulses, detailed information on such vibrations can be obtained. Also of great importance is the investigation of the energy transfer in artificial light-harvesting systems, e.g. in dendrimers. Finally the combination of experimental and theoretical investigations allows for a comparison of the spectra of two molecules wi

Scheer, Elke; Reineker, Peter

2008-06-01

343

Focused electron beam induced deposition: A perspective  

PubMed Central

Summary Background: Focused electron beam induced deposition (FEBID) is a direct-writing technique with nanometer resolution, which has received strongly increasing attention within the last decade. In FEBID a precursor previously adsorbed on a substrate surface is dissociated in the focus of an electron beam. After 20 years of continuous development FEBID has reached a stage at which this technique is now particularly attractive for several areas in both, basic and applied research. The present topical review addresses selected examples that highlight this development in the areas of charge-transport regimes in nanogranular metals close to an insulator-to-metal transition, the use of these materials for strain- and magnetic-field sensing, and the prospect of extending FEBID to multicomponent systems, such as binary alloys and intermetallic compounds with cooperative ground states. Results: After a brief introduction to the technique, recent work concerning FEBID of Pt–Si alloys and (hard-magnetic) Co–Pt intermetallic compounds on the nanometer scale is reviewed. The growth process in the presence of two precursors, whose flux is independently controlled, is analyzed within a continuum model of FEBID that employs rate equations. Predictions are made for the tunability of the composition of the Co–Pt system by simply changing the dwell time of the electron beam during the writing process. The charge-transport regimes of nanogranular metals are reviewed next with a focus on recent theoretical advancements in the field. As a case study the transport properties of Pt–C nanogranular FEBID structures are discussed. It is shown that by means of a post-growth electron-irradiation treatment the electronic intergrain-coupling strength can be continuously tuned over a wide range. This provides unique access to the transport properties of this material close to the insulator-to-metal transition. In the last part of the review, recent developments in mechanical strain-sensing and the detection of small, inhomogeneous magnetic fields by employing nanogranular FEBID structures are highlighted. Conclusion: FEBID has now reached a state of maturity that allows a shift of the focus towards the development of new application fields, be it in basic research or applied. This is shown for selected examples in the present review. At the same time, when seen from a broader perspective, FEBID still has to live up to the original idea of providing a tool for electron-controlled chemistry on the nanometer scale. This has to be understood in the sense that, by providing a suitable environment during the FEBID process, the outcome of the electron-induced reactions can be steered in a controlled way towards yielding the desired composition of the products. The development of a FEBID-specialized surface chemistry is mostly still in its infancy. Next to application development, it is this aspect that will likely be a guiding light for the future development of the field of focused electron beam induced deposition.

Porrati, Fabrizio; Schwalb, Christian; Winhold, Marcel; Sachser, Roland; Dukic, Maja; Adams, Jonathan; Fantner, Georg

2012-01-01

344

Focus Issue: Building Signaling Connections  

NSDL National Science Digital Library

The STKE Connections Maps database continues to flourish, with new canonical and specific pathways being added throughout the year, and the existing pathways being updated continuously. This year's Special Issue, published in conjunction with a series of Viewpoints in Science, highlights new canonical pathways in immunology [Interleukin 4 (IL-4) and IL-13 Pathways by Kelly-Welch et al. and the Toll-Like Receptor (TLR) Pathway by Barton and Medzhitov], as well as new canonical and specific pathways in neurobiology (Circadian Rhythm Pathways by Van Gelder and Granule Cell Survival Pathway by Leuillet et al.). In addition, the seven transmembrane family of receptors, which most often couple to heterotrimeric guanine nucleotide-binding proteins (G proteins) and are therefore best known as G protein-coupled receptors (GPCRs), are represented with new pathways and Viewpoints. These new pathways, which complement the existing Gαi, Gαs, Gαq, Gα12, and Gα13 seven transmembrane receptor signaling pathways by Iyengar and colleagues, include examples of G protein-independent signaling, as well as signaling pathways mediated by G proteins. Both a canonical and a specific pathway by Kimmel and Parent focus attention on the persistence of signaling from seven transmembrane adenosine 3′,5′ monophosphate (cAMP) receptors even in Dictyostelium discoidium deficient in various G protein genes. Kimmel and Parent also provide a pathway describing the D. discoidium G protein-mediated chemotactic response to cAMP. The seven transmembrane receptor signaling pathways also include a new pathway for Wnt signaling that describes emerging evidence that certain isoforms of Frizzled receptors--best known for their G protein-independent regulation of β-catenin stability and activation of β-catenin as a transcriptional regulator in response to Wnt--can also signal through G proteins to regulate intracellular calcium and guanosine 3′,5′-monophosphate (cGMP) concentrations. Finally, adrenoreceptor signaling, which has important clinical implications in heart disease, is featured in canonical and myocyte-specific pathways by Xiang and Kobilka.

Nancy R. Gough (American Association for the Advancement of Science;Managing Editor of Science's STKE REV); Elizabeth M. Adler (American Association for the Advancement of Science;Associate Editor of Science's STKE REV); L. Bryan Ray (American Association for the Advancement of Science;Editor of Science's STKE and Senior Editor of Science REV)

2003-06-10

345

Recent advances in microfluidic detection systems  

PubMed Central

There are numerous detection methods available for methods are being put to use for detection on these miniaturized systems, with the analyte of interest driving the choice of detection method. In this article, we summarize microfluidic 2 years. More focus is given to unconventional approaches to detection routes and novel strategies for performing high-sensitivity detection.

Baker, Christopher A; Duong, Cindy T; Grimley, Alix; Roper, Michael G

2009-01-01

346

Cold Neutron Focusing with a Wolter Type-I Mirror  

NASA Astrophysics Data System (ADS)

A cold neutron beam from a research reactor was focused using a Wolter type-I mirror which was originally designed for X-ray imaging. The optical system was installed at JRR-3 of Japan Atomic Energy Agency (JAEA). Focused neutron images were taken at wavelengths of 0.6 nm to about 1 nm and they were detected by an imaging plate. The spatial resolution obtained at the focal plane was about 100 ?m, which was limited mainly by the pixel size of the imaging plate.

Aoki, Sadao; Yamamoto, Tsuyoshi; Furukawa, Jun

2012-02-01

347

Dual-focus laser micro-machining  

NASA Astrophysics Data System (ADS)

This paper describes an optical configuration for generating dual-focus from a single laser incident beam. The generated two foci have nearly equivalent spot size and both fall on the optical axis of the focusing optics, but at different focal lengths. The dual-focus optics allows for variations of the laser power of each focal point and the distance between the two focal points. The advantages of dual-focus ablation were demonstrated with a nanosecond UV laser dicing silicon substrates. The experimental results show that, compared to conventional single focus, dual-focus improves ablation rate by a factor of 2 4.

Tan, B.; Venkatakrishnan, K.

2005-11-01

348

AXAF VETA-I mirror ring focus measurements  

NASA Technical Reports Server (NTRS)

The AXAF VETA-I mirror ring focus measurements were made with an HRI (microchannel plate) X-ray detector. The ring focus is a sharply focused ring formed by X-rays before they reach the VEAT-I focal plane. It is caused by spherical aberrations due to the finite source distance and the despace in the VETA-I test. The ring focus test reveals some aspects fo the test system distortions and the mirror surface figure which are difficult or impossible to detect at the focal plane. The test results show periodic modulations of the ring radius and width which could be caused by gravity, thermal, and/or epoxy shrinkage distortions. The strongest component of the modulation had a 12-fold symmetry, because these distortions were exerted on the mirror through 12 flexures of the VETA-I mount. Ring focus models were developed to simulate the ring image. The models were compared with the data to understand the test system distortions and the mirror glass imperfection. Further studies will be done to complete this work. The ring focus measurement is a very powerful test. We expect that a similar test for the finally assembled mirror of AXAD-I will be highly valuable.

Tananbaum, H. D.; Zhao, P.

1994-01-01

349

Automatic section thickness determination using an absolute gradient focus function.  

PubMed

Quantitative analysis of microstructures using computerized stereology systems is an essential tool in many disciplines of bioscience research. Section thickness determination in current nonautomated approaches requires manual location of upper and lower surfaces of tissue sections. In contrast to conventional autofocus functions that locate the optimally focused optical plane using the global maximum on a focus curve, this study identified by two sharp 'knees' on the focus curve as the transition from unfocused to focused optical planes. Analysis of 14 grey-scale focus functions showed, the thresholded absolute gradient function, was best for finding detectable bends that closely correspond to the bounding optical planes at the upper and lower tissue surfaces. Modifications to this function generated four novel functions that outperformed the original. The 'modified absolute gradient count' function outperformed all others with an average error of 0.56 ?m on a test set of images similar to the training set; and, an average error of 0.39 ?m on a test set comprised of images captured from a different case, that is, different staining methods on a different brain region from a different subject rat. We describe a novel algorithm that allows for automatic section thickness determination based on just out-of-focus planes, a prerequisite for fully automatic computerized stereology. PMID:23078150

Elozory, D T; Kramer, K A; Chaudhuri, B; Bonam, O P; Goldgof, D B; Hall, L O; Mouton, P R

2012-12-01

350

Low-dosage Maximum-A-Posteriori Focusing and Stigmation.  

PubMed

Radiation damage is often an issue during high-resolution imaging, making low-dose focusing and stigmation essential, in particular when no part of the sample can be "sacrificed" for this. An example is serial block-face electron microscopy, where the imaging resolution must be kept optimal during automated acquisition that can last months. Here, we present an algorithm, which we call "Maximum-A-Posteriori Focusing and Stigmation (MAPFoSt)," that was designed to make optimal use of the available signal. We show that MAPFoSt outperforms the built-in focusing algorithm of a commercial scanning electron microscope even at a tenfold reduced total dose. MAPFoSt estimates multiple aberration modes (focus and the two astigmatism coefficients) using just two test images taken at different focus settings. Using an incident electron dose density of 2,500 electrons/pixel and a signal-to-noise ratio of about one, all three coefficients could be estimated to within <7% of the depth of focus, using 19 detected secondary electrons per pixel. A generalization to higher-order aberrations and to other forms of imaging in both two and three dimensions appears possible. PMID:23380003

Binding, Jonas; Mikula, Shawn; Denk, Winfried

2013-02-01

351

Differential spot-size focus servo  

NASA Technical Reports Server (NTRS)

We describe performance of a differential spot-size (wax-wane) focus servo. Crosstalk from the tracks are analyzed in the single detector and differential focus circuits. Magnitude of the crosstalk is reduced by a factor of three in the differential circuit. A false focus-error signal (FES) is present when the spot crosses sector marks at an angle.

Milster, T. D.; Wang, M. S.; Froehlich, F. F.; Kann, J. L.; Treptau, J. P.; Erwin, K. E.

1991-01-01

352

Techniques For Focusing In Zone Electrophoresis  

NASA Technical Reports Server (NTRS)

In two techniques for focusing in zone electrophoresis, force of applied electrical field in each charged particle balanced by restoring force of electro-osmosis. Two techniques: velocity-gradient focusing (VGF), suitable for rectangular electrophoresis chambers; and field-gradient focusing (FGF), suitable for step-shaped electrophoresis chambers.

Sharnez, Rizwan; Twitty, Garland E.; Sammons, David W.

1994-01-01

353

Evaluation of focusing solar energy collectors  

Microsoft Academic Search

An introductory presentation is made concerning means of evaluating the performance of focusing solar energy collectors, with emphasis on common features among different focusing collectors. Term definitions, the advantages of focusing collectors, over flat-plate collectors methods of concentration, an illustrative example, and an economic evaluation criterion are discussed. It is concluded that the key information necessary to evaluate a collector

F. Kreith

1975-01-01

354

FR4 Laser Scanner With Dynamic Focus  

Microsoft Academic Search

An electromagnetically actuated optical scanner made using standard printed circuit board technology with integrated dynamic focusing feature is presented. Dynamic focus is achieved with an independently controlled plunger machined on the flame retardant-4 (FR4) platform. Integration of a laser diode and lens, torsional scanner, and the plunger for dynamic focus adjustment on FR4 platform greatly improves the form factor of

Serhan O. Isikman; Randy B. Sprague; Hakan Urey

2009-01-01

355

Laser focus compensating sensing and imaging device  

Microsoft Academic Search

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when

Vann; Charles S

1993-01-01

356

Focused attention in pervasively hyperactive children  

Microsoft Academic Search

This experiment was designed to investigate the hypothesized distractibility of hyperactive children in a focused attention task. Distractibility was defined in terms of Shiffrin and Schneider's model of focused attention as the ability to ignore irrelevant in favor of relevant information. Failure to inhibit processing of irrelevant information indicates a focused attention deficit. Task efficiency in all children decreased when

Jaap van der MeerU; Joseph Sergeant

1988-01-01

357

Second-order focusing parallel electron energy magnetic sector analyzer designs  

NASA Astrophysics Data System (ADS)

This paper presents parallel magnetic sector analyzer designs that are predicted to have second-order or better focusing properties. Simulation results indicate that by reducing the gap between excitation plates in a compact parallel energy magnetic sector box design, second-order focusing regions in the detected energy spectrum can be obtained. A method for combining a first-order focusing magnetic box sector unit with a larger magnet sector unit is also presented in which, the field strength varies relatively slowly. Simulations predict that using a combination of such magnetic sector units, focusing properties better than second order can be achieved for most of the detected energy range.

Khursheed, Anjam

2011-07-01

358

Three-dimensional hydrodynamic focusing in a microfluidic Coulter counter  

Microsoft Academic Search

Electrical impedance-based particle detection or Coulter counting, offers a lab-on-chip compatible method for flow cytometry. Developments in this area will produce devices with greater portability, lower cost, and lower power requirements than fluorescence-based flow cytometry. Because conventional Coulter apertures are prone to clogging, hydrodynamic focusing improves the device by creating fluid-walled channels with variable width to increase sensitivity without the

R. Scott; P. Sethu; C. K. Harnett

2008-01-01

359

Trapping cavitation bubbles with a self-focused laser beam  

Microsoft Academic Search

We observed that laser-induced cavitation bubbles in water can be trapped in a self-focused laser beam. Both optical imaging and acoustic detection have been utilized to confirm bubble trapping. Transverse and longitudinal trapping forces were measured to be as large as 87 and 11 pN, respectively. This result is contrary to conventional wisdom, since the mechanism of trapping in conventional

Jing Yong Ye; Guoqing Chang; Theodore B. Norris; Christine Tse; Marwa J. Zohdy; Kyle W. Hollman; Matthew O'Donnell; James R. Baker Jr.

2004-01-01

360

Automatic and voluntary focusing of attention.  

PubMed

In this study, we investigate whether attentional focusing, like attentional orienting, comprises two independent mechanisms. We provide direct empirical evidence in favor of the existence of two mechanisms--one exogenous, or automatic, and one endogenous, or voluntary--that play a role in adjusting the size of the focus of attention. When a new object suddenly occurs in the visual field, the focus is first automatically fitted to it, and then an endogenous effort has to be exerted to maintain attention in the focused mode. Also, we provide evidence that voluntary focusing needs a perceptual object in order to operate. PMID:10997040

Turatto, M; Benso, F; Facoetti, A; Galfano, G; Mascetti, G G; Umiltà, C

2000-07-01

361

Quantitative results from the focusing schlieren technique  

NASA Technical Reports Server (NTRS)

An iterative theoretical approach to obtain quantitative density data from the focusing schlieren technique is proposed. The approach is based on an approximate modeling of the focusing action in a focusing schlieren system, and an estimation of an appropriate focal plane thickness. The theoretical approach is incorporated in a computer program, and results obtained from a supersonic wind tunnel experiment evaluated by comparison with CFD data. The density distributions compared favorably with CFD predictions. However, improvements to the system are required in order to reduce noise in the data, to improve specifications of a depth of focus, and to refine the modeling of the focusing action.

Cook, S. P.; Chokani, Ndaona

1993-01-01

362

Autofocus for multispectral camera using focus symmetry.  

PubMed

A multispectral camera acquires spectral color images with high fidelity by splitting the light spectrum into more than three bands. Because of the shift of focal length with wavelength, the focus of each channel should be mechanically adjusted in order to obtain sharp images. Because progressive adjustment is quite time consuming, the clear focus must be determined by using a limited number of images. This paper exploits the symmetry of focus measure distribution and proposes a simple yet efficient autofocus method. The focus measures are computed using first-order image derivatives, and the focus curve is obtained by spline interpolation. The optimal focus position, which maximizes the symmetry of the focus measure distribution, is then computed according to distance metrics. The effectiveness of the proposed method is validated in the multispectral camera system, and it is also applicable to relevant imaging systems. PMID:22614481

Shen, Hui-Liang; Zheng, Zhi-Huan; Wang, Wei; Du, Xin; Shao, Si-Jie; Xin, John H

2012-05-10

363

Decoding the internal focus of attention  

PubMed Central

The significance of the recent introduction to cognitive neuroscience of multivariate pattern analysis (MVPA) is that, unlike univariate approaches which are limited to identifying magnitudes of activity in localized parts of the brain, it affords the detection and characterization of patterns of activity distributed within and across multiple brain regions. This technique supports stronger inferences because it captures neural representations that have markedly higher selectivity than do univariate activation peaks. Recently, we used MVPA to assess the neural consequences of dissociating the internal focus of attention from short-term memory (STM), finding that the information represented in delay-period activity corresponds only to the former (Lewis-Peacock, Drysdale, Oberauer, & Postle, in press). Here we report several additional analyses of these data in which we directly compared the results generated by MVPA vs. those generated by univariate analyses. The sensitivity of MVPA to subtle variations in patterns of distributed brain activity revealed a novel insight: Although overall activity remains elevated in category-selective brain regions corresponding to unattended STM items, the multivariate patterns of activity within these regions reflect the representation of a different category, i.e., the one that is currently being attended to. In addition, MVPA was able to dissociate attended from unattended STM items in brain regions whose univariate activity did not appear to be sensitive to the task. These findings highlight the fallacy of the assumption of homogeneity of representation within putative category-selective regions. They affirm the view that neural representations in STM are highly distributed and overlapping, and they demonstrate the necessity of multivariate analysis for dissociating such representations.

Lewis-Peacock, Jarrod A.; Postle, Bradley R.

2011-01-01

364

Focus and dose characterization of immersion photoclusters  

NASA Astrophysics Data System (ADS)

The process window for state of the art chip manufacturing continues to decrease, driven by higher NA exposure tools and lower k1 values. The benefits of immersion lithography for Depth of Focus (DoF) are well known. Yet even with this immersion boost, NA=1.35 tools can push DoF into sub-100nm territory. In addition, immersion processes are subject to new sources of dose and focus variation. In order to realize the full potential of immersion lithography, it is necessary to characterize, understand and attack all sources of process variation. Previous work has established our dose/focus metrology capability1, in which we expose Process Monitor Grating (PMG) targets with high sensitivity to focus, measure the PMGs using scatterometry, and use the Ausschnitt dose/focus deconvolution approach to determine focus errors to within a few nm and dose errors to within 0.1%. In this paper, we concentrate on applying this capability to the detailed measurements of immersion photoclusters utilizing ASML exposure tools. Results will include: • comparison of Twinscan 1700i and 1900i focus capability • effectiveness of the Reticle Shape Correction (RSC) for non-flat reticles • visualization of non-flat wafer chucks, tilted image planes, and other systematic focus error components • tracking of tool trends over time, using automated monitor wafer flows The highly systematic nature of the observed focus errors suggest potential for future improvements in focus capability.

Brunner, T. A.; Corliss, D.; Wiltshire, T.; Ausschnitt, C. P.

2009-03-01

365

Intrinsic Plagiarism Detection  

Microsoft Academic Search

Abstract Current research in the field of automatic plagiarism detection for text documents focuses on algorithms that compare plagiarized documents against potential original documents. Though these approaches perform well in identify-ing copied or even modified passages, they assume a closed world: a reference collection must be given against which a plagiarized document can be compared. This raises the question whether

Sven Meyer Zu Eissen; Benno Stein

2006-01-01

366

Dataflow Anomaly Detection  

Microsoft Academic Search

Beginning with the work of Forrest et al, several researchers have developed intrusion detection techniques based on modeling program behaviors in terms of system calls. A weakness of these techniques is that they focus on control flows involving system calls, but not their arguments. This weakness makes them susceptible to several classes of attacks, including attacks on security-critical data, race-condition

Sandeep Bhatkar; Abhishek Chaturvedi; R. Sekar

2006-01-01

367

Diffraction depth of focus in optical microscope  

NASA Astrophysics Data System (ADS)

The paper presents the mathematical technique for calculation of the diffraction depth of focus of an optical system of a widefield microscope. The proposed technique applies the Rayleigh criterion based on evaluation of the wave aberration appeared due to defocus in a high aperture optical system. The maximal value of a linear approximation of the defocus wave aberration is used to define the depth of focus. It is proven that in optical systems with numerical aperture higher than 0.5 have the diffraction depth of focus 25 - 40 % smaller than the widely known formula defines. This fact is important for implementation of autofocus and digital focus extension algorithms. The non-sophisticated formula for calculation of the depth of focus is proposed. The results of experimental measurements of the depth of focus are presented and discussed.

Borovytsky, Volodymyr; Fesenko, Andrey

2010-08-01

368

Phase-shift focus monitoring techniques  

NASA Astrophysics Data System (ADS)

Depth of focus (DOF) has become a victim of its mathematical relationship with Numerical Aperture (NA). While NA is being increased towards one to maximize scanner resolution capabilities, DOF is being minimized because of its inverse relationship with NA. Moore's law continues to drive the semiconductor industry towards smaller and smaller devices the need for high NA to resolve these shrinking devices will continue to consume the usable depth of focus (UDOF). Due to the shrinking UDOF a demand has been created for a feature or technology that will give engineers the capability to monitor scanner focus. Developing and implementation of various focus monitoring techniques have been used to prevent undetected tool focus excursions. Two overlay techniques to monitor ArF Scanner focus have been evaluated; our evaluation results will be presented here.

McQuillan, Matthew; Roberts, Bill

2006-04-01

369

Discrimination of positive particles emitted in deuterium plasma focus device using SSNTD  

Microsoft Academic Search

The yields of different positive particles emitted in deutherium plasma focus device were measured. The ? particles, among the other particles, were detected. CR-39 and LR-115 (Kodak) SSNTD were used.

Ž. Todorovi?; R. Antanasijevi?; D. Ševi?; A. Zari?; D. J. Konjevi?; J. Vukovi?; J. Puri?; M. ?uk

1995-01-01

370

Focusing neutrons with tapered capillary optics  

NASA Astrophysics Data System (ADS)

The transmission characteristics of radiation through hollow tapered capillaries may be described by expressions derived for straight capillaries but with a reduced critical angle. The size of the focused beam for recent transmission measurements through a tapered polycapillary focusing optic performed at various different wavelengths gives a measure of the reduced critical angle. We derive the transmission characteristics of the focusing lens from the measured data and compare these with the analytic results. A similar comparison is made for a polychromatic incident beam.

Mildner, D. F. R.; Chen-Mayer, H. H.; Gibson, W. M.

2002-12-01

371

Needs of Non Energy-Focused Contractors  

SciTech Connect

To better understand the informational needs of non energy-focused contractors, including what information they need to motivate them to become energy-focused, the BARA team studied the type of information provided by the national programs, trade associations, and manufacturers that were researched for the related technical report: Effective Communication of Energy Efficiency. While that report focused on the delivery method, format, and strategy of the information, this study examines the content being put forward.

Liaukus, C.

2012-12-01

372

Focusing polychromatic light through strongly scattering media.  

PubMed

We demonstrate feedback-optimized focusing of spatially coherent polychromatic light after transmission through strongly scattering media, and describe the relationship between optimized focus intensity and initial far-field speckle contrast. Optimization is performed using a MEMS spatial light modulator with camera-based or spectrometer-based feedback. We observe that the spectral bandwidth of the optimized focus depends on characteristics of the feedback signal. We interpret this dependence as a modification in the number of independent frequency components, or spectral correlations, transmitted by the sample, and introduce a simple model for polychromatic focus enhancement that is corroborated by experiment with calibrated samples. PMID:23938576

Paudel, Hari P; Stockbridge, Chris; Mertz, Jerome; Bifano, Thomas

2013-07-15

373

Semiclassical Inverse Spectral Theory for Singularities of Focus-Focus Type  

NASA Astrophysics Data System (ADS)

We prove, assuming that the Bohr-Sommerfeld rules hold, that the joint spectrum near a focus-focus singular value of a quantum integrable system determines the classical Lagrangian foliation around the full focus-focus leaf. The result applies, for instance, to ?-pseudodifferential operators on cotangent bundles and Berezin-Toeplitz operators on prequantizable compact symplectic manifolds.

Pelayo, Álvaro; Ng?c, San V?

2014-07-01

374

Laser-induced breakdown versus self-focusing for focused picosecond pulses in water  

NASA Astrophysics Data System (ADS)

We present numerical studies of nonlinear propagation for picosecond pulses focused in water. Depending on the pulse duration and focusing conditions, for some input powers self-focusing may precede laser-induced breakdown and vice versa. We derive a criterion that predicts the relative roles of laser-induced breakdown and self-focusing.

Feng, Q.; Moloney, J. V.; Newell, A. C.; Wright, E. M.

1995-10-01

375

A new focusing method for nondestructive evaluation by surface acoustic wave  

Microsoft Academic Search

The focalization of surface acoustic wave on piezoelectric substrates has been largely studied. It is of great interest, in the nondestructive testing area, to use focused surface acoustic waves to monitor defects like cracks which are hardly detected by acoustic bulk waves. In this paper, a new method for nondestructive testing is reported, which uses cylindrically focused surface acoustic beams.

B. Nongaillard; M. Ourak; J. M. Rouvaen; M. Houze; E. Bridoux

1984-01-01

376

Using Focus Group Research in Public Relations.  

ERIC Educational Resources Information Center

Analyzes a recent instance of focus group research applied to a public relations case (rather than a marketing case). Reviews the advantages and disadvantages of this qualitative method, and describes the case of a county department of mental health relying on focus group research to help plan a program aimed at reducing the stigma of mental…

Grunig, Larissa A.

1990-01-01

377

Focus Groups with Children: Do They Work?  

ERIC Educational Resources Information Center

Discusses the effectiveness of using focus groups with children to explore their information-seeking behavior and describes a study that organized focus groups with children to determine their opinions on currently available Web-based portals designed for children, and how they might be improved. (Author/LRW)

Large, Andrew; Beheshti, Jamshid

2001-01-01

378

On FOCUS: Photographs and Writings by Students.  

ERIC Educational Resources Information Center

Project FOCUS is aimed at enhancing literacy education for non-native speakers of English through the use of photography. It was offered as an elective course within a family literacy program for Hispanic adults. This collection of writings and photographs originated in the program. The collection begins with an overview of Project FOCUS, personal…

Strohmeyer, Beatriz; McGrail, Loren

379

Peer Led Focus Groups and Young People  

ERIC Educational Resources Information Center

Peer led focus groups, a qualitative social science research method, and their use with young people are examined. The paper outlines three developments that have contributed to their emergence, namely: traditional focus groups, peer education and participatory research. Drawing on a study in progress, the advantages and challenges associated with…

Murray, Cathy

2006-01-01

380

Inclusive Focus Particles in English and Korean  

ERIC Educational Resources Information Center

When discussing focus particles, it has been common practice to rely on the dichotomy of inclusive vs. exclusive particles, "a la" Konig (1991). Inclusive focus particles are often further divided into scalar particles, such as "also", "too", and "either", and non-scalar particles, such as "even". In this thesis, I advance a comparative analysis…

Kang, Sang-gu

2011-01-01

381

Neutron focusing lens using polycapillary fibers  

Microsoft Academic Search

Multiple mirror reflection at small grazing angles from the smooth surfaces of the narrow channels of polycapillary fibers can be used to transport, bend, and focus thermal neutron beams. We report the results of the focusing of a polychromatic cold neutron beam using a compact lens of borosilicate fibers and with a focal distance of 57 mm. The intensity profile

H. Chen; D. F. R. Mildner; Q. F. Xiao

1994-01-01

382

A scaling law for plasma focus devices  

Microsoft Academic Search

It is found that the neutron yield (N) in plasma focus devices is scalable with the sheet current (I sub S); here, N is approximately equal to I sub S to the 3.2 power. The efficiency of the current transfer into the sheet can be computed through a scaling law based on a simple fluid model. All focus machines, regardless

H. Krompholz; F. Ruehl; W. Schneider; K. Schoenbach; G. Herziger

1981-01-01

383

Interactive data visualization using focusing and linking  

Microsoft Academic Search

This paper discusses two basic principles for interactive visualization of high dimensional data: focusing and linking. The paper and the accompanying video give examples of how graphical data analysis methods based on focusing and linking are used in applications including linguistics, geographic information systems, time series analysis, of multi-channel images arising in radiology and remote sensing.

Andreas Buja; John Alan McDonald; John Michalak; Werner Stuetzle

1991-01-01

384

Mnemonic Instruction, with a Focus on Transfer.  

ERIC Educational Resources Information Center

Examines mnemonic transfer in the form of knowledge generalization in the context of an artwork-learning task. Results reveal that mnemonic instruction produced memory benefits on a direct test, and that on a transfer task, mnemonic students who were directed to focus on the general style of the artist outperformed students who focused on details…

Carney, Russell N.; Levin, Joel R.

2000-01-01

385

Near-field focused planar microstrip arrays  

Microsoft Academic Search

Near-field focused (NFF) antennas can significantly improve wireless system performance with respect to conventional far-field focused antennas when the receiver\\/target is located in the antenna near-field region. In this paper, a survey on the most recent results on NFF planar arrays will be presented.

A. Buffi; A. A. Serra; P. Nepa; G. Manara; H.-T. Chou

2011-01-01

386

2011 Service Academy Gender Relations Focus Groups.  

National Technical Information Service (NTIS)

The '2011 Service Academy Gender Relations Focus Group' ('2011 SAGR') study is a focus group assessment conducted per U.S. Code 10 as amended by Section 532 of the John Warner National Defense Authorization Act for Fiscal Year 2007. '2011 SAGR' is part of...

L. M. Rock P. J. Cook R. N. Lipari

2011-01-01

387

Identifying Information Focuses in Listening Comprehension  

ERIC Educational Resources Information Center

The study explains the process of learners' listening comprehension within Halliday's information theory in functional grammar, including the skills of identifying focuses while listening in college English teaching. Identifying information focuses in listening is proved to improve the students' communicative listening ability by the means of a…

Zhang, Hong-yan

2011-01-01

388

An auto-focusing CCD camera mount  

NASA Astrophysics Data System (ADS)

The traditional methods of focusing a CCD camera are either time consuming, difficult or, more importantly, indecisive. This paper describes a device designed to allow the observer to be confident that the camera will always be properly focused by sensing a selected star image and automatically adjusting the camera's focal position.

Arbour, R. W.

1994-08-01

389

Using Focused Conversation in the Classroom  

ERIC Educational Resources Information Center

Focused conversation is a method of collecting observations, emotions, interpretations, and decisions from groups that have shared a significant experience. This article reports how the author used focused conversation to discuss the events of September 11 with students in three sections of a master's-level organizational change class in the week…

Spee, James C.

2005-01-01

390

Focus Session Keynote Presentation on Student Development.  

ERIC Educational Resources Information Center

This address focuses upon the expected increases in enrollments of traditional college students in the first decade of the 21st Century, and the impact of this increase on community colleges is discussed. Much recent activity and research at community colleges have focused on adult education, workforce development, technological advancement and…

Nunley, Charlene R.

391

Focus finding using scale invariant patterns  

NASA Astrophysics Data System (ADS)

We present a new method for accurately determining the best focus position of a camera lens in the context of image quality evaluation and modulation transfer function (MTF) measurement. Our method makes use of the "live preview" function of digital cameras to image a test chart containing spatially and rotationally invariant alignment patterns. The patterns can be located to sub-pixel accuracy even under defocus using the technique of blur-invariant phase correlation, which leads to an absolute measure of focus position, independent of any backlash in the lens mechanism. We describe an efficient closed feedback loop algorithm which makes use of this to drive the lens rapidly to best focus. This method achieves the peak focus position to within a single step of the focus drive motor, typically allowing the peak focus MTF to be measured to within 1.4% RMS. The mean time taken to find the peak focus position and drive the focus motor back to that position ready for a comprehensive test exposure is 11.7 seconds, with maximum time 26 seconds, across a variety of lenses of varying focal lengths.

Morgan-Mar, David; Arnison, Matthew R.

2013-01-01

392

Practitioner-Focused Degrees in Politics  

Microsoft Academic Search

This article aims to explore practitioner-focused degrees in politics. It begins by defining the term and outlining the key features in comparison to other politics degrees. The underlying pedagogical principles that inform the design of teaching, learning, and assessment are then explored, before the article moves on to discuss the development of a suite of practitioner-focused degrees at the University

John Craig

2010-01-01

393

Sculpting on polymers using focused ion beam  

Microsoft Academic Search

It has been recently shown that ordered wrinkles can be created on the surface of polymers using focused ion beam irradiation. Here, we provide an overview of the techniques developed for controlled creation of nanoscale wrinkling patterns on the polymer surface using focused ion beam. Moreover, some of the key experimental challenges for precise fabrication of wrinkling patterns were investigated

M.-W. Moon; E.-K. Her; K. H. Oh; K.-R. Lee; A. Vaziri

2008-01-01

394

Diffraction analysis of focusing optical elements  

NASA Astrophysics Data System (ADS)

Potentialities of the computational experiment when studying focusing elements for laser light are analyzed. We substantiate the need for the computational experiment when choosing a method for solving ill-posed inverse problems of the diffraction theory and analyzing new types of elements to focus laser light, the feasibility and efficiency of the optical elements under predetermined physical parameters of an optical system.

Serafimovich, P. G.

2014-04-01

395

Focus Groups with Linguistically Marginalized Populations.  

ERIC Educational Resources Information Center

The focus group method has rapidly gained credibility among researchers in many fields, including public health researchers. The increased use of focus groups by public health researchers has underscored the demonstrable need for the capacity to apply this method of research among populations with limited abilities in or cultural resistance to…

Pardi, Marco M.

396

The Social Contexts of Focus Groups  

Microsoft Academic Search

This article argues that focus group discussions are shaped by multiple social contexts, a fact that is often ignored by researchers. Using data from a focus group study of the effects of violence on everyday life, this article provides an analysis of four such contexts: the associational, status (especially gender), conversational, and relational contexts. These multiple and overlapping contexts foster

Jocelyn A. Hollander

2004-01-01

397

How I Learned to Conduct Focus Groups  

ERIC Educational Resources Information Center

The use of focus groups may provide researchers with important insights into research questions via participant discussion and interaction. As a human services practitioner and researcher, I became interested in learning how to conduct focus groups in order to apply these steps to my research and gain valuable insights about the human experience…

Del Rio-Roberts, Maribel

2011-01-01

398

Attentional Focus Effects in Balance Acrobats  

ERIC Educational Resources Information Center

Performing and learning motor skills has been shown to be enhanced if the performer adopts an external relative to internal focus (or no focus) of attention (Wulf, 2007). The present study examined the generalizability of this effect to top-level performers (balance acrobats). Participants performed a balance task (standing on an inflated rubber…

Wulf, Gabriele

2008-01-01

399

What about focus group interaction data?  

PubMed

The purpose of this article is to discuss issues related to group interaction data in focus groups. How should it be analyzed and reported? The author addresses these questions using qualitative research approaches with examples from her research to foster further discussion regarding focus group research. PMID:15961879

Duggleby, Wendy

2005-07-01

400

The focusing of weak shock waves  

Microsoft Academic Search

The behavior of converging weak shock waves near caustics, aretes, and perfect foci was investigated on the basis of pressure measurements and shadowgraphs. Shocks were focused by reflecting initially plane fronts from concave end walls in a large shock tube. An essentially nonlinear complex wave field developed near the focus of a shock discontinuity. Increased sound speed and nonlinear steepening

B. Sturtevant; V. A. Kulkarny

1976-01-01

401

Final focus systems for linear colliders  

SciTech Connect

The final focus system of a linear collider must perform two primary functions, it must focus the two opposing beams so that their transverse dimensions at the interaction point are small enough to yield acceptable luminosity, and it must steer the beams together to maintain collisions. In addition, the final focus system must transport the outgoing beams to a location where they can be recycled or safely dumped. Elementary optical considerations for linear collider final focus systems are discussed, followed by chromatic aberrations. The design of the final focus system of the SLAC Linear Collider (SLC) is described. Tuning and diagnostics and steering to collision are discussed. Most of the examples illustrating the concepts covered are drawn from the SLC, but the principles and conclusions are said to be generally applicable to other linear collider designs as well. 26 refs., 17 figs. (LEW)

Erickson, R.A.

1987-11-01

402

Thermal imaging for anxiety detection  

Microsoft Academic Search

We propose a revolutionary concept for detecting suspects engaged in illegal and potentially harmful activities in or around critical military or civilian installations. We investigate the use of thermal image analysis to detect at a distance facial patterns of anxiety, alertness, and\\/or fearfulness. This is a totally novel approach to the problem of biometric identification. Instead of focusing on the

I. Pavlidis; J. Levine; P. Baukol

2000-01-01

403

Tanks Focus Area annual report FY2000  

SciTech Connect

The U.S. Department of Energy (DOE) continues to face a major radioactive waste tank remediation effort with tanks containing hazardous and radioactive waste resulting from the production of nuclear materials. With some 90 million gallons of waste in the form of solid, sludge, liquid, and gas stored in 287 tanks across the DOE complex, containing approximately 650 million curies, radioactive waste storage tank remediation is the nation's highest cleanup priority. Differing waste types and unique technical issues require specialized science and technology to achieve tank cleanup in an environmentally acceptable manner. Some of the waste has been stored for over 50 years in tanks that have exceeded their design lives. The challenge is to characterize and maintain these contents in a safe condition and continue to remediate and close each tank to minimize the risks of waste migration and exposure to workers, the public, and the environment. In 1994, the DOE's Office of Environmental Management (EM) created a group of integrated, multiorganizational teams focusing on specific areas of the EM cleanup mission. These teams have evolved into five focus areas managed within EM's Office of Science and Technology (OST): Tanks Focus Area (TFA); Deactivation and Decommissioning Focus Area; Nuclear Materials Focus Area; Subsurface Contaminants Focus Area; and Transuranic and Mixed Waste Focus Area.

None

2000-12-01

404

Laser focus compensating sensing and imaging device  

DOEpatents

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Vann, Charles S. (Fremont, CA)

1993-01-01

405

Laser focus compensating sensing and imaging device  

DOEpatents

A laser focus compensating sensing and imaging device permits the focus of a single focal point of different frequency laser beams emanating from the same source point. In particular it allows the focusing of laser beam originating from the same laser device but having differing intensities so that a low intensity beam will not convert to a higher frequency when passing through a conversion crystal associated with the laser generating device. The laser focus compensating sensing and imaging device uses a Cassegrain system to fold the lower frequency, low intensity beam back upon itself so that it will focus at the same focal point as a high intensity beam. An angular tilt compensating lens is mounted about the secondary mirror of the Cassegrain system to assist in alignment. In addition cameras or CCD's are mounted with the primary mirror to sense the focused image. A convex lens is positioned co-axial with the Cassegrain system on the side of the primary mirror distal of the secondary for use in aligning a target with the laser beam. A first alternate embodiment includes a Cassegrain system using a series of shutters and an internally mounted dichroic mirror. A second alternate embodiment uses two laser focus compensating sensing and imaging devices for aligning a moving tool with a work piece.

Vann, C.S.

1993-08-31

406

Deep-Focusing Time-Distance Helioseismology  

NASA Technical Reports Server (NTRS)

Much progress has been made by measuring the travel times of solar acoustic waves from a central surface location to points at equal arc distance away. Depth information is obtained from the range of arc distances examined, with the larger distances revealing the deeper layers. This method we will call surface-focusing, as the common point, or focus, is at the surface. To obtain a clearer picture of the subsurface region, it would, no doubt, be better to focus on points below the surface. Our first attempt to do this used the ray theory to pick surface location pairs that would focus on a particular subsurface point. This is not the ideal procedure, as Born approximation kernels suggest that this focus should have zero sensitivity to sound speed inhomogeneities. However, the sensitivity is concentrated below the surface in a much better way than the old surface-focusing method, and so we expect the deep-focusing method to be more sensitive. A large sunspot group was studied by both methods. Inversions based on both methods will be compared.

Duvall, T. L., Jr.; Jensen, J. M.; Kosovichev, A. G.; Birch, A. C.; Fisher, Richard R. (Technical Monitor)

2001-01-01

407

Focus optimization of the SPIRIT III radiometer  

NASA Astrophysics Data System (ADS)

The spatial infrared imaging telescope (SPIRIT III) radiometer is the primary instrument aboard the Midcourse Space Experiment (MSX), which was launched on April 24, 1997. The Space Dynamics Laboratory at Utah State University (SDL/USU) developed and implemented a ground-based procedure to optimize the focus of the SPIRIT III radiometer. The procedure used point source data acquired during ground measurements. These measurements were obtained with a calibration source consisting of an illuminated pinhole near the focus of a cryogenically cooled collimator. Simulated point source measurements were obtained at multiple focus positions by translating the pinhole along the optical axis inside and outside the optimum focus of the collimator. The radiometer was found to be slightly out of focus, and the detector focal plane arrays were moved to positions indicated by the test results. This method employed a single cryogenic cycle to measure both the distance and direction needed to adjust each array for optimal focus. The results of the SPIRIT III on- orbit stellar point source observation demonstrate the success of the technique. The method and hardware used to achieve focus optimization are described.

Tansock, Joseph J.; Shumway, Andrew L.

1997-11-01

408

Focus optimization of the SPIRIT III radiometer  

NASA Astrophysics Data System (ADS)

The SPIRIT III (spatial infrared imaging telescope) radiometer is the primary instrument aboard the midcourse space experiment (MSX), which was launched on 24 April 1997. The Space Dynamics Laboratory at Utah State University (SDL/USU) developed and implemented a ground-based procedure to optimize the focus of the SPIRIT III radiometer. The procedure used point source data acquired during ground measurements. These measurements were obtained with a calibration source consisting of an illuminated pinhole near the focus of a cryogenically cooled collimator. Simulated point source measurements were obtained at multiple focus positions by translating the pinhole along the optical axis inside and outside the optimum focus of the collimator. The radiometer was found to be slightly out of focus, and the detector focal plane arrays were moved to positions indicated by the test results. This method employed a single cryogenic cycle to measure both the distance and direction needed to adjust each array for optimal focus. The results of the SPIRIT III on- orbit stellar point source observation demonstrate the success of the technique. This paper describes the method and hardware used to achieve focus optimization.

Tansock, Joseph J.; Shumway, Andrew L.

1997-10-01

409

Three-dimensional hydrodynamic focusing in a microfluidic Coulter counter  

NASA Astrophysics Data System (ADS)

Electrical impedance-based particle detection or Coulter counting, offers a lab-on-chip compatible method for flow cytometry. Developments in this area will produce devices with greater portability, lower cost, and lower power requirements than fluorescence-based flow cytometry. Because conventional Coulter apertures are prone to clogging, hydrodynamic focusing improves the device by creating fluid-walled channels with variable width to increase sensitivity without the associated risk of blocking the channel. We describe a device that focuses the sample in three dimensions, creating a narrow sample stream on the floor of the channel for close interaction with sensing electrodes. The key to this design is a stepped outlet channel fabricated in a single layer with soft lithography. In contrast to previous impedance-based designs, the new design requires minimal alignment with the substrate. Three-dimensional focusing maximizes the sensitivity of the device to cell-size particles within much larger channels. Impedance-based particle sensing experiments within this device show an increase in percentage conductivity change by a factor of 2.5 over devices that only focus the sample in the horizontal direction.

Scott, R.; Sethu, P.; Harnett, C. K.

2008-04-01

410

Three-dimensional hydrodynamic focusing in a microfluidic Coulter counter.  

PubMed

Electrical impedance-based particle detection or Coulter counting, offers a lab-on-chip compatible method for flow cytometry. Developments in this area will produce devices with greater portability, lower cost, and lower power requirements than fluorescence-based flow cytometry. Because conventional Coulter apertures are prone to clogging, hydrodynamic focusing improves the device by creating fluid-walled channels with variable width to increase sensitivity without the associated risk of blocking the channel. We describe a device that focuses the sample in three dimensions, creating a narrow sample stream on the floor of the channel for close interaction with sensing electrodes. The key to this design is a stepped outlet channel fabricated in a single layer with soft lithography. In contrast to previous impedance-based designs, the new design requires minimal alignment with the substrate. Three-dimensional focusing maximizes the sensitivity of the device to cell-size particles within much larger channels. Impedance-based particle sensing experiments within this device show an increase in percentage conductivity change by a factor of 2.5 over devices that only focus the sample in the horizontal direction. PMID:18447562

Scott, R; Sethu, P; Harnett, C K

2008-04-01

411

Isoelectric focusing of sarcoplasmic proteins to distinguish swordfish, blue marlin and Mediterranean spearfish  

Microsoft Academic Search

In the present study we show that the method of isoelectric focusing (IEF) is a simple and reliable one for detecting the fraudulent substitution of cold-smoked fillets of swordfish (Xiphias gladius) with those of lower value blue marlin (Makaira mazara) and for detecting substitution of blue marlin steaks with those of Mediterranean spearfish (Tetrapturus belone). The cold smoking process does

P. Renon; C. Bernardi; R. Malandra; P. A. Biondi

2005-01-01

412

Integration of Single Ion Implantation Method in Focused Ion Beam System for Nanofabrication  

Microsoft Academic Search

A method of single ion implantation based on the online detection of individual ion impacts on a pure silicon substrate has been implemented in a focused ion beam (FIB) system. The optimized silicon detector integrated with a state-of-art low noise electronic system and operated at a low temperature makes it possible to achieve single ion detection with a minimum energy

Changyi Yang; David N. Jamieson; Sean Hearne; Toby Hopf; Chris Pakes; S teven Prawer; Søren E. Andresen; Andrew Dzurak; E. Gauja; F. E. Hudson; R. G. Clark

2006-01-01

413

Designing focusing solenoids for superconducting RF accelerators  

SciTech Connect

The design of a focusing solenoid for use in a superconducting RF linac requires resolving a range of problems with conflicting requirements. Providing the required focusing strength contradicts the goal of minimizing the stray field on the surfaces of adjacent superconducting RF cavities. The requirement of a compact solenoid, able to fit into a gap between cavities, contradicts the need of mechanical support necessary to restrain electromagnetic forces that can result in coil motion and subsequent quenching. In this report we will attempt to address these and other issues arising during the development of focusing solenoids. Some relevant test data will also be presented.

Davis, G.; Kashikhin, V.V.; Page, T.; Terechkine, I.; Tompkins, J.; Wokas, T.; /Fermilab

2006-08-01

414

Neutron focusing lens using polycapillary fibers  

SciTech Connect

Multiple mirror reflection at small grazing angles from the smooth surfaces of the narrow channels of polycapillary fibers can be used to transport, bend, and focus thermal neutron beams. We report the results of the focusing of a polychromatic cold neutron beam using a compact lens of borosilicate fibers and with a focal distance of 57 mm. The intensity profile of the beam at the focus is approximately conical in shape with a full width at half-maximum of 0.49 mm, and with an average gain in intensity of about 20. These experimental results agree well with those obtained by computer simulation.

Chen, H.; Mildner, D.F.R. (National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)); Xiao, Q.F. (X-Ray Optical Systems, Inc., Albany, New York 12222 (United States))

1994-04-18

415

A sharp-focusing schlieren optical deflectometer  

NASA Technical Reports Server (NTRS)

A new instrument capable of localized, nonintrusive turbulence measurements is developed by combining a focusing schlieren system with an optical deflectometer. This instrument records the fluctuating light intensity at a point in the focused schlieren image. Its capability is verified by making benchmark measurements of Kelvin-Helmholtz vortices produced in a low-speed axisymmetric mixing layer. The sharp-focusing effect is demonstrated both visually and quantitatively. The results show that the instrument is capable of optical turbulence measurements within a 4 mm depth-of-field.

Alvi, F. S.; Settles, G. S.; Weinstein, L. M.

1993-01-01

416

Focused ion beam source method and apparatus  

DOEpatents

A focused ion beam having a cross section of submicron diameter, a high ion current, and a narrow energy range is generated from a target comprised of particle source material by laser ablation. The method involves directing a laser beam having a cross section of critical diameter onto the target, producing a cloud of laser ablated particles having unique characteristics, and extracting and focusing a charged particle beam from the laser ablated cloud. The method is especially suited for producing focused ion beams for semiconductor device analysis and modification.

Pellin, Michael J. (Naperville, IL); Lykke, Keith R. (Gaithersburg, MD); Lill, Thorsten B. (Sunnyvale, CA)

2000-01-01

417

Auto focus and image registration techniques for infrared imaging of microelectronic devices  

NASA Astrophysics Data System (ADS)

An infrared (IR) microscope camera system is used to measure the temperature distribution of power devices during electrical stress pulses. A calibration is required to correlate the target temperature to the corresponding raw data of the IR camera. The IR microscope camera system contains a fixed lens; this means that the whole camera has to be moved to detect focus images. During the heating up or cooling down process, the thermo-mechanical expansion influences the measurement results. For the calibration of the power device, focus images and a pixel-by-pixel registration of individual images are required. In this paper, methods are discussed to prepare the images for the calibration process. The issues concerning finding the focus image and guaranteeing a pixel-by-pixel overlap in the image sequence are solved and evaluated by the proposed auto focus and the image correlation algorithms. An IR camera equipped with a fixed focus lens is used to perform the measurements; hence, no geometrical distortion occurs. To detect the focus position and corresponding focus image, the principle of passive focusing is used, where a focus curve is recorded. Different methods are discussed to compute the focus value. Image registration is applied to compute the distortion between the images and guarantee a pixel-by-pixel overlap. In our case, the most significant parameter is the displacement; hence, the SIFT algorithm of Lowe and a simple image correlation algorithm are implemented and compared.

Florian, Daniela; Köck, Helmut; Plankensteiner, Kathrin; Glavanovics, Michael

2013-07-01

418

Elliptic neutron guides—focusing on tiny samples  

NASA Astrophysics Data System (ADS)

We have investigated the focusing properties of the prototype of a transportable elliptic neutron guide. We demonstrate that the elliptic guide allows to map a point-like neutron source in one focal point on a tiny spot in the other focal point. We also show that an elliptically tapered neutron guide increases the neutron flux density in the focal point by at least one order of magnitude compared to the flux density of the original neutron beam. This allows to use neutron beams more efficiently in experiments with small samples. We used the elliptic neutron guide to focus a several centimeters wide neutron beam on a tiny NiS2 sample with the dimensions 0.1 mm3 and easily detected the ordered moment of this antiferromagnetic insulator. This suggests that many more small samples, in particular in high pressure experiments, can be studied with elliptic neutron guides.

Mühlbauer, S.; Niklowitz, P. G.; Stadlbauer, M.; Georgii, R.; Link, P.; Stahn, J.; Böni, P.

2008-02-01

419

Focus Issue: A Niche of One's Own  

NSDL National Science Digital Library

In this Focus Issue of Science Signaling, which complements the Science Special Issue on Microbial Ecology (http://www.sciencemag.org/microbialecology/), we explore signaling mechanisms whereby microbes—both benign and pathogenic—interact with their hosts.

Elizabeth M. Adler (American Association for the Advancement of Science;Science Signaling REV); John F. Foley (American Association for the Advancement of Science;Science Signaling REV)

2008-05-27

420

Adjustable Focus Optical Correction Lens (AFOCL).  

National Technical Information Service (NTIS)

This report describes the activities and accomplishments along with the status of the characterization of a PLZT-based Adjustable Focus Optical Correction Lens (AFOCL) test device. The activities described in this report were undertaken by members of the ...

B. R. Peters

2001-01-01

421

NAS Forums Focus on National Science Topics  

ERIC Educational Resources Information Center

A series of public meetings designed to focus on complex and persistent problems of national importance involving science has been launched. Topics such as drugs, energy, and natural disasters are included. (DF)

Chemical and Engineering News, 1973

1973-01-01

422

Automatic Focusing Devices for Photographic Cameras.  

National Technical Information Service (NTIS)

Automatic focusing systems for either still or movie cameras are defined. System requirements, depending on camera characteristics (aperture), lighting conditions or the use of high-speed color film, are identified. Passive and active systems are consider...

K. Birgmeier A. Hell

1980-01-01

423

Periodic magnetic focusing of sheet electron beams  

SciTech Connect

Sheet electron beams focused by periodically cusped magnetic (PCM) fields are stable against low-frequency velocity-shear instabilities (such as the diocotron mode). This is in contrast to the more familiar unstable behavior in uniform solenoidal magnetic fields. A period-averaged analytic model shows that a PCM-focused beam is stabilized by ponderomotive forces for short PCM periods. Numerical particle simulations for a semi-infinite sheet beam verify this prediction and also indicate diocotron stability for long PCM periods is less constraining than providing for space-charge confinement and trajectory stability in the PCM focusing system. In this article the issue of beam matching and side focusing for sheet beams of finite width is also discussed. A review of past and present theoretical and experimental investigations of sheet-beam transport is presented.

Booske, J.H.; Basten, M.A.; Kumbasar, A.H. (Electrical and Computer Engineering, University of Wisconsin---Madison, Madison, Wisconsin 53706 (United States)); Antonsen, T.M. Jr.; Bidwell, S.W.; Carmel, Y.; Destler, W.W.; Granatstein, V.L.; Radack, D.J. (Laboratory for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States))

1994-05-01

424

Laue focusing effect and its applications  

NASA Astrophysics Data System (ADS)

The focusing of neutrons by means of symmetric Laue-geometry diffraction from thin perfect crystals has been studied. Applications of the effect to small-angle neutron scattering, single crystal, and powder diffraction experiments have been investigated.

Kvardakov, V. V.; Somenkov, V. A.; Lynn, J. W.; Mildner, D. F. R.; Chen, H.

1998-04-01

425

Laue focusing effect and its applications  

NASA Astrophysics Data System (ADS)

The focusing of neutrons by means of symmetric Laue-geometry diffraction from thin perfect crystals has been studied. Applications of the effect to small-angle neutron scattering, single crystal, and powder diffraction experiments have been investigated.

Kvardakov, V. V.; Somenkov, V. A.; Lynn, J. W.; Mildner, D. F. R.; Chen, H.

426

Aerodynamic Focusing of Nanoparticle or Cluster Beams.  

National Technical Information Service (NTIS)

Guidelines for designing lenses or systems for aerodynamic focusing of nanoparticle or cluster beams. The design process may involve obtaining a relationship between particle size, operating pressure and aperture size, and selecting the operating pressure...

F. E. Kruis P. H. McMurry X. Wang

2005-01-01

427

Family Preservation (Family Focus Research Project).  

National Technical Information Service (NTIS)

The Family Focus Research project provided a comprehensive evaluation of home-based crisis intervention strategies for families with children at risk of placement into substitute care. It examined the relative costs and benefits of three types of brief, i...

J. R. Taplin C. Rowland

1983-01-01

428

Focusing Internet Searches for World Music Resources  

ERIC Educational Resources Information Center

Discusses the importance of focusing Internet searches for world music resources. Importance of teaching about music from various cultures; Benefits of identifying a characteristic instrument by name or stylistic terms; Types of music web sites.

Mishra, Jennifer

2004-01-01

429

Hydrodynamic focusing of a particle flux  

SciTech Connect

Based on numerical integration of the equations of mechanics of multiphase media, an effect of focusing of a particle flux generated by a source located on the upper wall of a closed vessel has been revealed and investigated.

Makhviladze, G.M.; Melikhov, O.I.; Nikolova, I.P. [Institute of Mechanics and Biomechanics, Sofia (Bulgaria)

1995-12-01

430

Apparatus for focusing flowing gas streams  

DOEpatents

Apparatus for focusing gas streams. The principle of hydrodynamic focusing is applied to flowing gas streams in order to provide sample concentration for improved photon and sample utilization in resonance ionization mass spectrometric analysis. In a concentric nozzle system, gas samples introduced from the inner nozzle into the converging section of the outer nozzle are focused to streams 50-250-..mu..m in diameter. In some cases diameters of approximately 100-..mu..m are maintained over distances of several centimeters downstream from the exit orifice of the outer nozzle. The sheath gas employed has been observed to further provide a protective covering around the flowing gas sample, thereby isolating the flowing gas sample from possible unwanted reactions with nearby surfaces. A single nozzle variation of the apparatus for achieving hydrodynamic focusing of gas samples is also described.

Nogar, N.S.; Keller, R.A.

1985-05-20

431

Generation of arbitrarily focused images by using multiple differently focused images  

NASA Astrophysics Data System (ADS)

In the paper, we propose a novel method of arbitrarily focused image acquisition using multiple differently focused images. First, we describe our previous select-and-merge method for all-focused image acquisition. We can get god results by using this method but it's not easy to extend this method for generating arbitrarily focused images. Then, based on the assumption that depth of the scene changes stepwise, we derive a formula for reconstruction between the desired arbitrarily focused image and multiple acquired images; we can reconstruct the arbitrarily focused image by iterative use of the formula. We al