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Sample records for hac trial harmonic

  1. [A New HAC Unsupervised Classifier Based on Spectral Harmonic Analysis].

    PubMed

    Yang, Ke-ming; Wei, Hua-feng; Shi, Gang-qiang; Sun, Yang-yang; Liu, Fei

    2015-07-01

    Hyperspectral images classification is one of the important methods to identify image information, which has great significance for feature identification, dynamic monitoring and thematic information extraction, etc. Unsupervised classification without prior knowledge is widely used in hyperspectral image classification. This article proposes a new hyperspectral images unsupervised classification algorithm based on harmonic analysis(HA), which is called the harmonic analysis classifer (HAC). First, the HAC algorithm counts the first harmonic component and draws the histogram, so it can determine the initial feature categories and the pixel of cluster centers according to the number and location of the peak. Then, the algorithm is to map the waveform information of pixels to be classified spectrum into the feature space made up of harmonic decomposition times, amplitude and phase, and the similar features can be gotten together in the feature space, these pixels will be classified according to the principle of minimum distance. Finally, the algorithm computes the Euclidean distance of these pixels between cluster center, and merges the initial classification by setting the distance threshold. so the HAC can achieve the purpose of hyperspectral images classification. The paper collects spectral curves of two feature categories, and obtains harmonic decomposition times, amplitude and phase after harmonic analysis, the distribution of HA components in the feature space verified the correctness of the HAC. While the HAC algorithm is applied to EO-1 satellite Hyperion hyperspectral image and obtains the results of classification. Comparing with the hyperspectral image classifying results of K-MEANS, ISODATA and HAC classifiers, the HAC, as a unsupervised classification method, is confirmed to have better application on hyperspectral image classification.

  2. HAC: Band Gap, Photoluminescence, and Optical/Near-Infrared Absorption

    NASA Technical Reports Server (NTRS)

    Witt, Adolf N.; Ryutov, Dimitri; Furton, Douglas G.

    1996-01-01

    We report results of laboratory measurements which illustrate the wide range of physical properties found among hydrogenated amorphous carbon (HAC) solids. Within this range, HAC can match quantitatively the astronomical phenomena ascribed to carbonaceous coatings on interstellar grains. We find the optical band gap of HAC to be well correlated with other physical properties of HAC of astronomical interest, and conclude that interstellar HAC must be fairly hydrogen-rich with a band gap of E(sub g) is approx. greater than 2.0 eV.

  3. HAC: Band Gap, Photoluminescence, and Optical/Near-Infrared Absorption

    NASA Technical Reports Server (NTRS)

    Witt, Adolf N.; Ryutov, Dimitri; Furton, Douglas G.

    1996-01-01

    We report results of laboratory measurements which illustrate the wide range of physical properties found among hydrogenated amorphous carbon (HAC) solids. Within this range, HAC can match quantitatively the astronomical phenomena ascribed to carbonaceous coatings on interstellar grains. We find the optical band gap of HAC to be well correlated with other physical properties of HAC of astronomical interest, and conclude that interstellar HAC must be fairly hydrogen-rich with a band gap of E(sub g) is approx. greater than 2.0 eV.

  4. Allergen Immunotherapy Clinical Trial Outcomes and Design: Working Toward Harmonization of Methods and Principles.

    PubMed

    Nelson, Harold S; Calderon, Moises A; Bernstein, David I; Casale, Thomas B; Durham, Stephen R; Andersen, Jens S; Esch, Robert; Cox, Linda S; Nolte, Hendrik

    2017-03-01

    Progress has been made in the harmonization of efficacy and safety outcome measures for allergen immunotherapy (AIT) trials, but unresolved issues still remain. Furthermore, there are discrepancies in recommendations from professional medical societies and regulatory agencies regarding requirements for AIT trials. In this article, we reviewed published recommendations and current data from recent clinical trials, as well as the criteria applied by regulatory authorities for approval of AIT products, to provide updated considerations for conducting phase 3 AIT trials. Topics discussed include analysis of outcomes and trial designs for pediatric and asthma indications, as well as trial designs for perennial allergic rhinoconjunctivitis. In addition, the need for harmonization of safety reporting is emphasized. Considerations presented in this article may further effort to find common ground among professional medical societies and government agencies in developing future recommendations for AIT trial design.

  5. Global Harmonization of Quality Assurance Naming Conventions in Radiation Therapy Clinical Trials

    SciTech Connect

    Melidis, Christos; Bosch, Walther R.; Izewska, Joanna; Fidarova, Elena; Zubizarreta, Eduardo; Ulin, Kenneth; Ishikura, Satoshi; Followill, David; Galvin, James; Haworth, Annette; Besuijen, Deidre; Clark, Clark H.; Miles, Elizabeth; Aird, Edwin; and others

    2014-12-01

    Purpose: To review the various radiation therapy quality assurance (RTQA) procedures used by the Global Clinical Trials RTQA Harmonization Group (GHG) steering committee members and present the harmonized RTQA naming conventions by amalgamating procedures with similar objectives. Methods and Materials: A survey of the GHG steering committee members' RTQA procedures, their goals, and naming conventions was conducted. The RTQA procedures were classified as baseline, preaccrual, and prospective/retrospective data capture and analysis. After all the procedures were accumulated and described, extensive discussions took place to come to harmonized RTQA procedures and names. Results: The RTQA procedures implemented within a trial by the GHG steering committee members vary in quantity, timing, name, and compliance criteria. The procedures of each member are based on perceived chances of noncompliance, so that the quality of radiation therapy planning and treatment does not negatively influence the trial measured outcomes. A comparison of these procedures demonstrated similarities among the goals of the various methods, but the naming given to each differed. After thorough discussions, the GHG steering committee members amalgamated the 27 RTQA procedures to 10 harmonized ones with corresponding names: facility questionnaire, beam output audit, benchmark case, dummy run, complex treatment dosimetry check, virtual phantom, individual case review, review of patients' treatment records, and protocol compliance and dosimetry site visit. Conclusions: Harmonized RTQA harmonized naming conventions, which can be used in all future clinical trials involving radiation therapy, have been established. Harmonized procedures will facilitate future intergroup trial collaboration and help to ensure comparable RTQA between international trials, which enables meta-analyses and reduces RTQA workload for intergroup studies.

  6. Harmonization and streamlining of research oversight for pragmatic clinical trials.

    PubMed

    O'Rourke, P Pearl; Carrithers, Judith; Patrick-Lake, Bray; Rice, Todd W; Corsmo, Jeremy; Hart, Raffaella; Drezner, Marc K; Lantos, John D

    2015-10-01

    The oversight of research involving human participants is a complex process that requires institutional review board review as well as multiple non-institutional review board institutional reviews. This multifaceted process is particularly challenging for multisite research when each site independently completes all required local reviews. The lack of inter-institutional standardization can result in different review outcomes for the same protocol, which can delay study operations from start-up to study completion. Hence, there have been strong calls to harmonize and thus streamline the research oversight process. Although the institutional review board is only one of the required reviews, it is often identified as the target for harmonization and streamlining. Data regarding variability in decision-making and interpretation of the regulations across institutional review boards have led to a perception that variability among institutional review boards is a primary contributor to the problems with review of multisite research. In response, many researchers and policymakers have proposed the use of a single institutional review board of record, also called a central institutional review board, as an important remedy. While this proposal has merit, the use of a central institutional review board for multisite research does not address the larger problem of completing non-institutional review board institutional review in addition to institutional review board review—and coordinating the interdependence of these reviews. In this article, we describe the overall research oversight process, distinguish between institutional review board and institutional responsibilities, and identify challenges and opportunities for harmonization and streamlining. We focus on procedural and organizational issues and presume that the protection of human subjects remains the paramount concern. Suggested modifications of institutional review board processes that focus on time

  7. [Harmonization procedures directed toward clinical trials in laboratory medicine at the National Cancer Center Hospital].

    PubMed

    Ozeki, Mitsuru; Shioya, Kana; Furuta, Koh

    2009-09-01

    Recent advances in pharmacology and molecular sciences made it possible to develop drugs for patients with various maladies. Frustration has existed concerning the delayed provision of these drugs for routine practices in the clinical field. To correct this problem, the importance of clinical trials is increasing. Although there exists a strong demand for participation of clinical laboratories in clinical trials, an awkward attitude in clinical laboratories frustrates those performing clinical trials. We are attempting to correct this problem by introducing our experience with harmonization procedures directed toward clinical trials in laboratory medicine in general. First we described the current status of clinical trials in our hospital. Then we will show personnel in need for clinical trials. Finally we describe in detail our clinical trial procedures. We focus particularly on three aspects of participation in clinical trials: pre-analytical, analytical, and post analytical. Additionally we describe the problems and perspectives in clinical trials by giving special reference to the clinical laboratories in general through discussion with various personnel and specialists. Our goal in the field of laboratory medicine is to benefit patients through the establishment of a harmony between clinical trials and clinical laboratories.

  8. Harmonic scalpel versus bipolar tonsillectomy: a double-blind clinical trial.

    PubMed

    Kemal, Ozgur

    2012-05-01

    This is a double bind clinical trial which evaluated harmonic scalpel versus bipolar diathermy tonsillectomy The study was conducted at Diyarbakir government hospital, Diyarbakir, Turkey. The study population comprised 144 patients, aged 4-18 years (mean 9 years ± 4.12 SD). All patients underwent tonsillectomy with or without adenoidectomy. The indications for tonsillectomy were obstructive sleep apnea (84 patients [58.3%]) and chronic tonsillitis (60 patients [41.7%]). All 144 patients were randomly divided into two groups: bipolar dissection (81 patients [56.2%] with mean age 8.98 years ± 4.22) and harmonic scalpel (63 patients [43.8%] with mean age 9 years ± 4.02). BD group showed statistically significantly less intraoperative bleeding (< 0.05). There was no statistically significant difference on postoperative day 1 but a statistically significant difference was determined on postoperative days 4, 7 and 14. There was no statistically significant difference between the two techniques with regard to immediate and delayed bleeding. The mean operative time was the same in both the groups. Bipolar dissection group showed statistically significant less intraoperative bleeding than harmonic scalpel group. An analysis of postoperative pain scores showed that the harmonic scalpel group pain scores are lower than the bipolar dissection group on all recorded days, and no statistically significant complications was seen in both groups. The results of this study indicate that the HS technique is associated with lower pain scores with the same complication rates as the BD technique.

  9. OsHAC1;1 and OsHAC1;2 Function as Arsenate Reductases and Regulate Arsenic Accumulation.

    PubMed

    Shi, Shulin; Wang, Tao; Chen, Ziru; Tang, Zhong; Wu, Zhongchang; Salt, David E; Chao, Dai-Yin; Zhao, Fang-Jie

    2016-11-01

    Rice is a major dietary source of the toxic metalloid arsenic (As). Reducing its accumulation in rice (Oryza sativa) grain is of critical importance to food safety. Rice roots take up arsenate and arsenite depending on the prevailing soil conditions. The first step of arsenate detoxification is its reduction to arsenite, but the enzyme(s) catalyzing this reaction in rice remains unknown. Here, we identify OsHAC1;1 and OsHAC1;2 as arsenate reductases in rice. OsHAC1;1 and OsHAC1;2 are able to complement an Escherichia coli mutant lacking the endogenous arsenate reductase and to reduce arsenate to arsenite. OsHAC1:1 and OsHAC1;2 are predominantly expressed in roots, with OsHAC1;1 being abundant in the epidermis, root hairs, and pericycle cells while OsHAC1;2 is abundant in the epidermis, outer layers of cortex, and endodermis cells. Expression of the two genes was induced by arsenate exposure. Knocking out OsHAC1;1 or OsHAC1;2 decreased the reduction of arsenate to arsenite in roots, reducing arsenite efflux to the external medium. Loss of arsenite efflux was also associated with increased As accumulation in shoots. Greater effects were observed in a double mutant of the two genes. In contrast, overexpression of either OsHAC1;1 or OsHAC1;2 increased arsenite efflux, reduced As accumulation, and enhanced arsenate tolerance. When grown under aerobic soil conditions, overexpression of either OsHAC1;1 or OsHAC1;2 also decreased As accumulation in rice grain, whereas grain As increased in the knockout mutants. We conclude that OsHAC1;1 and OsHAC1;2 are arsenate reductases that play an important role in restricting As accumulation in rice shoots and grain.

  10. Focus Harmonic Scalpel Compared to Conventional Haemostasis in Open Total Thyroidectomy: A Prospective Randomized Trial

    PubMed Central

    Ferri, Emanuele; Armato, Enrico; Spinato, Giacomo; Spinato, Roberto

    2011-01-01

    The aim of this prospective randomized trial was to compare operative factors, postoperative outcomes and surgical complications of open total thyroidectomy when using the Harmonic Scalpel (HS) versus Conventional Haemostasis (CH). Methods. 100 consecutive patients underwent open total thyroidectomy were randomized into two groups: group CH (Conventional Haemostasis) and group HS (Harmonic Scalpel). We recorded the following: age, sex, pathology, thyroid volume, haemostatic technique, operative time, drainage volume, thyroid weight, postoperative pain, postoperative complications, and hospital stay. The results were analyzed using the Student's t test and χ2 test. Results. No significant difference was found between the two groups concerning mean thyroid weight and mean hospital stay. The mean operative time was significantly shorter in the HS group. The total drainage fluid volume was lower in HS group. Two (4%) transient recurrent laryngeal nerve palsies were observed in CH group and no one (0%) in the HS group. Postoperative transient hypocalcemia occurred more frequently in the CH group. HS group experienced significantly less postoperative pain at 24 and 48 hours. Conclusions. In patients undergoing thyroidectomy, HS is a reliable and safe tool. Comparing with CH techniques, its use reduces operative times, postoperative pain, drainage volume and transient hypocalcemia. PMID:22187563

  11. Region duplication forgery detection technique based on SURF and HAC.

    PubMed

    Mishra, Parul; Mishra, Nishchol; Sharma, Sanjeev; Patel, Ravindra

    2013-01-01

    Region duplication forgery detection is a special type of forgery detection approach and widely used research topic under digital image forensics. In copy move forgery, a specific area is copied and then pasted into any other region of the image. Due to the availability of sophisticated image processing tools, it becomes very hard to detect forgery with naked eyes. From the forged region of an image no visual clues are often detected. For making the tampering more robust, various transformations like scaling, rotation, illumination changes, JPEG compression, noise addition, gamma correction, and blurring are applied. So there is a need for a method which performs efficiently in the presence of all such attacks. This paper presents a detection method based on speeded up robust features (SURF) and hierarchical agglomerative clustering (HAC). SURF detects the keypoints and their corresponding features. From these sets of keypoints, grouping is performed on the matched keypoints by HAC that shows copied and pasted regions.

  12. Region Duplication Forgery Detection Technique Based on SURF and HAC

    PubMed Central

    Mishra, Parul; Sharma, Sanjeev; Patel, Ravindra

    2013-01-01

    Region duplication forgery detection is a special type of forgery detection approach and widely used research topic under digital image forensics. In copy move forgery, a specific area is copied and then pasted into any other region of the image. Due to the availability of sophisticated image processing tools, it becomes very hard to detect forgery with naked eyes. From the forged region of an image no visual clues are often detected. For making the tampering more robust, various transformations like scaling, rotation, illumination changes, JPEG compression, noise addition, gamma correction, and blurring are applied. So there is a need for a method which performs efficiently in the presence of all such attacks. This paper presents a detection method based on speeded up robust features (SURF) and hierarchical agglomerative clustering (HAC). SURF detects the keypoints and their corresponding features. From these sets of keypoints, grouping is performed on the matched keypoints by HAC that shows copied and pasted regions. PMID:24311972

  13. Organization of Synthetic Alphoid DNA Array in Human Artificial Chromosome (HAC) with a Conditional Centromere

    PubMed Central

    Kouprina, Natalay; Samoshkin, Alexander; Erliandri, Indri; Nakano, Megumi; Lee, Hee-Sheung; Fu, Haiging; Iida, Yuichi; Aladjem, Mirit; Oshimura, Mitsuo; Masumoto, Hiroshi; Earnshaw, William C.; Larionov, Vladimir

    2012-01-01

    Human artificial chromosomes (HACs) represent a novel promising episomal system for functional genomics, gene therapy and synthetic biology. HACs are engineered from natural and synthetic alphoid DNA arrays upon transfection into human cells. The use of HACs for gene expression studies requires the knowledge of their structural organization. However, none of de novo HACs constructed so far has been physically mapped in detail. Recently we constructed a synthetic alphoidtetO-HAC that was successfully used for expression of full-length genes to correct genetic deficiencies in human cells. The HAC can be easily eliminated from cell populations by inactivation of its conditional kinetochore. This unique feature provides a control for phenotypic changes attributed to expression of HAC-encoded genes. This work describes organization of a megabase-size synthetic alphoid DNA array in the alphoidtetO-HAC that has been formed from a ~50 kb synthetic alphoidtetO-construct. Our analysis showed that this array represents a 1.1 Mb continuous sequence assembled from multiple copies of input DNA, a significant part of which was rearranged before assembling. The tandem and inverted alphoid DNA repeats in the HAC range in size from 25 to 150 kb. In addition, we demonstrated that the structure and functional domains of the HAC remains unchanged after several rounds of its transfer into different host cells. The knowledge of the alphoidtetO-HAC structure provides a tool to control HAC integrity during different manipulations. Our results also shed light on a mechanism for de novo HAC formation in human cells. PMID:23411994

  14. Involvement of Arabidopsis histone acetyltransferase HAC family genes in the ethylene signaling pathway.

    PubMed

    Li, Chao; Xu, Jiang; Li, Jian; Li, Qingyun; Yang, Hongchun

    2014-02-01

    Epigenetic modifications play a fundamental role in regulating chromatin dynamics and gene expression. The level of histone acetylation is controlled by two functionally antagonistic enzymes, namely histone acetyltransferase (HAT) and histone deacetylase (HDAC). CREB-binding protein (CBP)/p300 proteins, a subfamily of highly conserved HATs, are involved in various physiological events including proliferation, differentiation and apoptosis. In this work, we study the poorly known function of their homologous genes, the HAC genes, in Arabidopsis. We found that hac1-involved mutants displayed pleiotropic phenotypes, in particular hypersensitivity to ethylene both in the dark and in the light. We also found that the transcriptional levels of ethylene-responsive genes are significantly higher in the hac1hac5 double mutant than in wild-type plants. Moreover, an ethylene synthesis inhibitor cannot release the triple responses of hac mutants. These results suggest that HACs are involved in the ethylene signaling pathway.

  15. Re-engineering an alphoidtetO-HAC-based vector to enable high-throughput analyses of gene function

    PubMed Central

    Kononenko, Artem V.; Lee, Nicholas C. O.; Earnshaw, William C.; Kouprina, Natalay; Larionov, Vladimir

    2013-01-01

    Human artificial chromosome (HAC)-based vectors represent an alternative technology for gene delivery and expression with a potential to overcome the problems caused by the use of viral-based vectors. The recently developed alphoidtetO-HAC has an advantage over other HAC vectors because it can be easily eliminated from cells by inactivation of the HAC kinetochore via binding of tTS chromatin modifiers to its centromeric tetO sequences. This provides unique control for phenotypes induced by genes loaded into the alphoidtetO-HAC. However, inactivation of the HAC kinetochore requires transfection of cells by a retrovirus vector, a step that is potentially mutagenic. Here, we describe an approach to re-engineering the alphoidtetO-HAC that allows verification of phenotypic changes attributed to expression of genes from the HAC without a transfection step. In the new HAC vector, a tTS-EYFP cassette is inserted into a gene-loading site along with a gene of interest. Expression of the tTS generates a self-regulating fluctuating heterochromatin on the alphoidtetO-HAC that induces fast silencing of the genes on the HAC without significant effects on HAC segregation. This silencing of the HAC-encoded genes can be readily recovered by adding doxycycline. The newly modified alphoidtetO-HAC-based system has multiple applications in gene function studies. PMID:23558748

  16. Re-engineering an alphoid(tetO)-HAC-based vector to enable high-throughput analyses of gene function.

    PubMed

    Kononenko, Artem V; Lee, Nicholas C O; Earnshaw, William C; Kouprina, Natalay; Larionov, Vladimir

    2013-05-01

    Human artificial chromosome (HAC)-based vectors represent an alternative technology for gene delivery and expression with a potential to overcome the problems caused by the use of viral-based vectors. The recently developed alphoid(tetO)-HAC has an advantage over other HAC vectors because it can be easily eliminated from cells by inactivation of the HAC kinetochore via binding of tTS chromatin modifiers to its centromeric tetO sequences. This provides unique control for phenotypes induced by genes loaded into the alphoid(tetO)-HAC. However, inactivation of the HAC kinetochore requires transfection of cells by a retrovirus vector, a step that is potentially mutagenic. Here, we describe an approach to re-engineering the alphoid(tetO)-HAC that allows verification of phenotypic changes attributed to expression of genes from the HAC without a transfection step. In the new HAC vector, a tTS-EYFP cassette is inserted into a gene-loading site along with a gene of interest. Expression of the tTS generates a self-regulating fluctuating heterochromatin on the alphoid(tetO)-HAC that induces fast silencing of the genes on the HAC without significant effects on HAC segregation. This silencing of the HAC-encoded genes can be readily recovered by adding doxycycline. The newly modified alphoid(tetO)-HAC-based system has multiple applications in gene function studies.

  17. A PILOT STUDY OF THE INFLUENCE OF RESIDENTIAL HAC DUTY CYCLE ON INDOOR AIR QUALITY (AE)

    EPA Science Inventory

    A simple methodology was developed to collect measurements of duty cycle, the fraction of time the heating and air conditioning (HAC) system was operating, inside residences. The primary purpose of the measurements was to assess whether the HAC duty cycle was related to reductio...

  18. A PILOT STUDY OF THE INFLUENCE OF RESIDENTIAL HAC DUTY CYCLE ON INDOOR AIR QUALITY

    EPA Science Inventory

    A simple methodology was developed to collect measurements of duty cycle, the fraction of time the heating and air conditioning (HAC) system was operating inside residences. The primary purpose of the measurements was to assess whether the HAC duty cycle was related to reducti...

  19. A PILOT STUDY OF THE INFLUENCE OF RESIDENTIAL HAC DUTY CYCLE ON INDOOR AIR QUALITY

    EPA Science Inventory

    A simple methodology was developed to collect measurements of duty cycle, the fraction of time the heating and air conditioning (HAC) system was operating inside residences. The primary purpose of the measurements was to assess whether the HAC duty cycle was related to reducti...

  20. The Yeast Rab GTPase Ypt1 Modulates Unfolded Protein Response Dynamics by Regulating the Stability of HAC1 RNA

    PubMed Central

    Tsvetanova, Nikoleta G.; Riordan, Daniel P.; Brown, Patrick O.

    2012-01-01

    The unfolded protein response (UPR) is a conserved mechanism that mitigates accumulation of unfolded proteins in the ER. The yeast UPR is subject to intricate post-transcriptional regulation, involving recruitment of the RNA encoding the Hac1 transcription factor to the ER and its unconventional splicing. To investigate the mechanisms underlying regulation of the UPR, we screened the yeast proteome for proteins that specifically interact with HAC1 RNA. Protein microarray experiments revealed that HAC1 interacts specifically with small ras GTPases of the Ypt family. We characterized the interaction of HAC1 RNA with one of these proteins, the yeast Rab1 homolog Ypt1. We found that Ypt1 protein specifically associated in vivo with unspliced HAC1 RNA. This association was disrupted by conditions that impaired protein folding in the ER and induced the UPR. Also, the Ypt1-HAC1 interaction depended on IRE1 and ADA5, the two genes critical for UPR activation. Decreasing expression of the Ypt1 protein resulted in a reduced rate of HAC1 RNA decay, leading to significantly increased levels of both unspliced and spliced HAC1 RNA, and delayed attenuation of the UPR, when ER stress was relieved. Our findings establish that Ypt1 contributes to regulation of UPR signaling dynamics by promoting the decay of HAC1 RNA, suggesting a potential regulatory mechanism for linking vesicle trafficking to the UPR and ER homeostasis. PMID:22844259

  1. Contrast-harmonic endoscopic ultrasound for the diagnosis of pancreatic adenocarcinoma: a prospective multicenter trial.

    PubMed

    Gincul, Rodica; Palazzo, Maxime; Pujol, Bertrand; Tubach, Florence; Palazzo, Laurent; Lefort, Christine; Fumex, Fabien; Lombard, Alexandra; Ribeiro, Daniel; Fabre, Monique; Hervieu, Valerie; Labadie, Michel; Ponchon, Thierry; Napoléon, Bertrand

    2014-05-01

    Histology is the gold standard for the diagnosis of pancreatic adenocarcinoma. However, the negative predictive value of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for the diagnosis remains low. The aims of this prospective multicenter study were: (1) to compare the performance of contrast-harmonic EUS (CH-EUS) with that of EUS-FNA for the diagnosis of pancreatic adenocarcinoma; (2) to assess the intra- and interobserver concordances of CH-EUS. A total of 100 consecutive patients with a solid pancreatic mass of unknown origin were prospectively included at three centers (July 2009 - April 2010). All patients were examined by CH-EUS followed by EUS-FNA. Absence of vascular enhancement at CH-EUS was regarded as a sign for pancreatic adenocarcinoma. The final diagnosis (gold standard) was based on pathological examination (EUS-FNA, surgery) or 12-month follow-up.  The final diagnoses were: 69 adenocarcinoma, 10 neuroendocrine tumors, 13 chronic pancreatitis, and 8 other lesions. In diagnosing adenocarcinoma, CH-EUS and EUS-FNA had respective accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 95 %, 96 %, 94 %, 97 %, and 91 %, and of 95 %, 93 %, 100 %, 100 %, and 86 % without significant difference. Five false-negative cases with EUS-FNA were correctly classified by CH-EUS. Interobserver agreement (seven endosonographers) was good (kappa 0.66). Intraobserver agreement was good to excellent (kappa 0.76 for junior, 0.90 for senior). The performance of CH-EUS for the diagnosis of pancreatic adenocarcinoma was excellent. The good intra- and interobserver concordances suggest an excellent reproducibility. CH-EUS could help to guide the choice between surgery and follow-up when EUS-FNA is inconclusive. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Harmonizing international trials of early goal-directed resuscitation for severe sepsis and septic shock: methodology of ProCESS, ARISE, and ProMISe

    PubMed Central

    2013-01-01

    Purpose To describe and compare the design of three independent but collaborating multicenter trials of early goal-directed resuscitation for severe sepsis and septic shock. Methods We reviewed the three current trials, one each in the USA (ProCESS: protocolized care for early septic shock), Australasia (ARISE: Australasian resuscitation in sepsis evaluation), and the UK (ProMISe: protocolised management in sepsis). We used the 2010 CONSORT (consolidated standards of reporting trials) statement and the 2008 CONSORT extension for trials assessing non-pharmacologic treatments to describe and compare the underlying rationale, commonalities, and differences. Results All three trials conform to CONSORT guidelines, address the same fundamental questions, and share key design elements. Each trial is a patient-level, equal-randomized, parallel-group superiority trial that seeks to enroll emergency department patients with inclusion criteria that are consistent with the original early goal-directed therapy (EGDT) trial (suspected or confirmed infection, two or more systemic inflammatory response syndrome criteria, and refractory hypotension or elevated lactate), is powered to detect a 6–8 % absolute mortality reduction (hospital or 90-day), and uses trained teams to deliver EGDT. Design differences appear to primarily be driven by between-country variation in health care context. The main difference between the trials is the inclusion of a third, alternative resuscitation strategy arm in ProCESS. Conclusions Harmonization of study design and methods between severe sepsis trials is feasible and may facilitate pooling of data on completion of the trials. PMID:23958738

  3. The fail-safe mechanism of post-transcriptional silencing of unspliced HAC1 mRNA

    PubMed Central

    Di Santo, Rachael; Aboulhouda, Soufiane; Weinberg, David E

    2016-01-01

    HAC1 encodes a transcription factor that is the central effector of the unfolded protein response (UPR) in budding yeast. When the UPR is inactive, HAC1 mRNA is stored as an unspliced isoform in the cytoplasm and no Hac1 protein is detectable. Intron removal is both necessary and sufficient to relieve the post-transcriptional silencing of HAC1 mRNA, yet the precise mechanism by which the intron prevents Hac1 protein accumulation has remained elusive. Here, we show that a combination of inhibited translation initiation and accelerated protein degradation—both dependent on the intron—prevents the accumulation of Hac1 protein when the UPR is inactive. Functionally, both components of this fail-safe silencing mechanism are required to prevent ectopic production of Hac1 protein and concomitant activation of the UPR. Our results provide a mechanistic understanding of HAC1 regulation and reveal a novel strategy for complete post-transcriptional silencing of a cytoplasmic mRNA. DOI: http://dx.doi.org/10.7554/eLife.20069.001 PMID:27692069

  4. Generating a transgenic mouse line stably expressing human MHC surface antigen from a HAC carrying multiple genomic BACs.

    PubMed

    Hasegawa, Yoshinori; Ishikura, Tomoyuki; Hasegawa, Takanori; Watanabe, Takashi; Suzuki, Junpei; Nakayama, Manabu; Okamura, Yoshiaki; Okazaki, Tuneko; Koseki, Haruhiko; Ohara, Osamu; Ikeno, Masashi; Masumoto, Hiroshi

    2015-03-01

    The human artificial chromosome (HAC) vector is a promising tool to improve the problematic suppression and position effects of transgene expression frequently seen in transgenic cells and animals produced by conventional plasmid or viral vectors. We generated transgenic mice maintaining a single HAC vector carrying two genomic bacterial artificial chromosomes (BACs) from human HLA-DR loci (DRA and DRB1). Both transgenes on the HAC in transgenic mice exhibited tissue-specific expression in kidney, liver, lung, spleen, lymph node, bone marrow, and thymus cells in RT-PCR analysis. Stable functional expression of a cell surface HLA-DR marker from both transgenes, DRA and DRB1 on the HAC, was detected by flow cytometric analysis of splenocytes and maintained through at least eight filial generations. These results indicate that the de novo HAC system can allow us to manipulate multiple BAC transgenes with coordinated expression as a surface antigen through the generation of transgenic animals.

  5. Human artificial chromosome (HAC) vector with a conditional centromere for correction of genetic deficiencies in human cells.

    PubMed

    Kim, Jung-Hyun; Kononenko, Artem; Erliandri, Indri; Kim, Tae-Aug; Nakano, Megumi; Iida, Yuichi; Barrett, J Carl; Oshimura, Mitsuo; Masumoto, Hiroshi; Earnshaw, William C; Larionov, Vladimir; Kouprina, Natalay

    2011-12-13

    Human artificial chromosome (HAC)-based vectors offer a promising system for delivery and expression of full-length human genes of any size. HACs avoid the limited cloning capacity, lack of copy number control, and insertional mutagenesis caused by integration into host chromosomes that plague viral vectors. We previously described a synthetic HAC that can be easily eliminated from cell populations by inactivation of its conditional kinetochore. Here, we demonstrate the utility of this HAC, which has a unique gene acceptor site, for delivery of full-length genes and correction of genetic deficiencies in human cells. A battery of functional tests was performed to demonstrate expression of NBS1 and VHL genes from the HAC at physiological levels. We also show that phenotypes arising from stable gene expression can be reversed when cells are "cured" of the HAC by inactivating its kinetochore in proliferating cell populations, a feature that provides a control for phenotypic changes attributed to expression of HAC-encoded genes. This generation of human artificial chromosomes should be suitable for studies of gene function and therapeutic applications.

  6. SCFCdc4-mediated degradation of the Hac1p transcription factor regulates the unfolded protein response in Saccharomyces cerevisiae.

    PubMed

    Pal, Bhupinder; Chan, Nickie C; Helfenbaum, Leon; Tan, Kaeling; Tansey, William P; Gething, Mary-Jane

    2007-02-01

    The Saccharomyces cerevisiae basic leucine zipper transcription factor Hac1p is synthesized in response to the accumulation of unfolded polypeptides in the lumen of the endoplasmic reticulum (ER), and it is responsible for up-regulation of approximately 5% of all yeast genes, including ER-resident chaperones and protein-folding catalysts. Hac1p is one of the most short-lived yeast proteins, having a half-life of approximately 1.5 min. Here, we have shown that Hac1p harbors a functional PEST degron and that degradation of Hac1p by the proteasome involves the E2 ubiquitin-conjugating enzyme Ubc3/Cdc34p and the SCF(Cdc4) E3 complex. Consistent with the known nuclear localization of Cdc4p, rapid degradation of Hac1p requires the presence of a functional nuclear localization sequence, which we demonstrated to involve basic residues in the sequence (29)RKRAKTK(35). Two-hybrid analysis demonstrated that the PEST-dependent interaction of Hac1p with Cdc4p requires Ser146 and Ser149. Turnover of Hac1p may be dependent on transcription because it is inhibited in cell mutants lacking Srb10 kinase, a component of the SRB/mediator module of the RNA polymerase II holoenzyme. Stabilization of Hac1p by point mutation or deletion, or as the consequence of defects in components of the degradation pathway, results in increased unfolded protein response element-dependent transcription and improved cell viability under ER stress conditions.

  7. SCFCdc4-mediated Degradation of the Hac1p Transcription Factor Regulates the Unfolded Protein Response in Saccharomyces cerevisiae

    PubMed Central

    Pal, Bhupinder; Chan, Nickie C.; Helfenbaum, Leon; Tan, Kaeling; Tansey, William P.

    2007-01-01

    The Saccharomyces cerevisiae basic leucine zipper transcription factor Hac1p is synthesized in response to the accumulation of unfolded polypeptides in the lumen of the endoplasmic reticulum (ER), and it is responsible for up-regulation of ∼5% of all yeast genes, including ER-resident chaperones and protein-folding catalysts. Hac1p is one of the most short-lived yeast proteins, having a half-life of ∼1.5 min. Here, we have shown that Hac1p harbors a functional PEST degron and that degradation of Hac1p by the proteasome involves the E2 ubiquitin-conjugating enzyme Ubc3/Cdc34p and the SCFCdc4 E3 complex. Consistent with the known nuclear localization of Cdc4p, rapid degradation of Hac1p requires the presence of a functional nuclear localization sequence, which we demonstrated to involve basic residues in the sequence 29RKRAKTK35. Two-hybrid analysis demonstrated that the PEST-dependent interaction of Hac1p with Cdc4p requires Ser146 and Ser149. Turnover of Hac1p may be dependent on transcription because it is inhibited in cell mutants lacking Srb10 kinase, a component of the SRB/mediator module of the RNA polymerase II holoenzyme. Stabilization of Hac1p by point mutation or deletion, or as the consequence of defects in components of the degradation pathway, results in increased unfolded protein response element-dependent transcription and improved cell viability under ER stress conditions. PMID:17108329

  8. Telomerase-mediated life-span extension of human primary fibroblasts by human artificial chromosome (HAC) vector

    SciTech Connect

    Shitara, Shingo; Kakeda, Minoru; Nagata, Keiko; Hiratsuka, Masaharu; Sano, Akiko; Osawa, Kanako; Okazaki, Akiyo; Katoh, Motonobu; Kazuki, Yasuhiro; Oshimura, Mitsuo; Tomizuka, Kazuma

    2008-05-09

    Telomerase-mediated life-span extension enables the expansion of normal cells without malignant transformation, and thus has been thought to be useful in cell therapies. Currently, integrating vectors including the retrovirus are used for human telomerase reverse transcriptase (hTERT)-mediated expansion of normal cells; however, the use of these vectors potentially causes unexpected insertional mutagenesis and/or activation of oncogenes. Here, we established normal human fibroblast (hPF) clones retaining non-integrating human artificial chromosome (HAC) vectors harboring the hTERT expression cassette. In hTERT-HAC/hPF clones, we observed the telomerase activity and the suppression of senescent-associated SA-{beta}-galactosidase activity. Furthermore, the hTERT-HAC/hPF clones continued growing beyond 120 days after cloning, whereas the hPF clones retaining the silent hTERT-HAC senesced within 70 days. Thus, hTERT-HAC-mediated episomal expression of hTERT allows the extension of the life-span of human primary cells, implying that gene delivery by non-integrating HAC vectors can be used to control cellular proliferative capacity of primary cultured cells.

  9. Effect of sodium zirconium cyclosilicate on potassium lowering for 28 days among outpatients with hyperkalemia: the HARMONIZE randomized clinical trial.

    PubMed

    Kosiborod, Mikhail; Rasmussen, Henrik S; Lavin, Philip; Qunibi, Wajeh Y; Spinowitz, Bruce; Packham, David; Roger, Simon D; Yang, Alex; Lerma, Edgar; Singh, Bhupinder

    2014-12-03

    Hyperkalemia is a common electrolyte abnormality that may be difficult to manage because of a lack of effective therapies. Sodium zirconium cyclosilicate is a nonabsorbed cation exchanger that selectively binds potassium in the intestine. To evaluate the efficacy and safety of zirconium cyclosilicate for 28 days in patients with hyperkalemia. HARMONIZE was a phase 3, multicenter, randomized, double-blind, placebo-controlled trial evaluating zirconium cyclosilicate in outpatients with hyperkalemia (serum potassium ≥5.1 mEq/L) recruited from 44 sites in the United States, Australia, and South Africa (March-August 2014). Patients (n = 258) received 10 g of zirconium cyclosilicate 3 times daily in the initial 48-hour open-label phase. Patients (n = 237) achieving normokalemia (3.5-5.0 mEq/L) were then randomized to receive zirconium cyclosilicate, 5 g (n = 45 patients), 10 g (n = 51), or 15 g (n = 56), or placebo (n = 85) daily for 28 days. The primary end point was mean serum potassium level in each zirconium cyclosilicate group vs placebo during days 8-29 of the randomized phase. In the open-label phase, serum potassium levels declined from 5.6 mEq/L at baseline to 4.5 mEq/L at 48 hours. Median time to normalization was 2.2 hours, with 84% of patients (95% CI, 79%-88%) achieving normokalemia by 24 hours and 98% (95% CI, 96%-99%) by 48 hours. In the randomized phase, serum potassium was significantly lower during days 8-29 with all 3 zirconium cyclosilicate doses vs placebo (4.8 mEq/L [95% CI, 4.6-4.9], 4.5 mEq/L [95% CI, 4.4-4.6], and 4.4 mEq/L [95% CI, 4.3-4.5] for 5 g, 10 g, and 15 g; 5.1 mEq/L [95% CI, 5.0-5.2] for placebo; P < .001 for all comparisons). The proportion of patients with mean potassium <5.1 mEq/L during days 8-29 was significantly higher in all zirconium cyclosilicate groups vs placebo (36/45 [80%], 45/50 [90%], and 51/54 [94%] for the 5-g, 10-g, and 15-g groups, vs 38/82 [46%] with placebo; P < .001 for each dose

  10. HAC-POA policy effects on hospitals, other payers, and patients.

    PubMed

    Sorensen, Asta; Jarrett, Nikki; Tant, Elizabeth; Bernard, Shulamit; McCall, Nancy

    2014-01-01

    Prior to the implementation of the Hospital-Acquired Condition-Present on Admission (HAC-POA) payment policy, concerns regarding its potential impact were raised by a number of organizations and individuals. The purpose of this study was to explore direct and indirect effects of the HAC-POA payment policy on hospitals, patients, and other payers during the policy's first 3 years of implementation. The study included semi-structured telephone interviews with representatives of national organizations, hospitals, patient advocacy organizations, and other payers. Interview notes were coded using QSR NVivo qualitative analysis software using inductive and deductive qualitative analysis techniques. We conducted interviews with 106 individuals representing 56 organizations. Hospital staff included physicians, nurses, patient safety officers, coders, and finance, senior management, and information management staff. Individuals from other organizations represented leadership positions. Key changes to hospitals included: cultural shifts involving attention, commitment, and support from hospital leadership for patient safety; hiring new staff to assure the accuracy of clinical documentation and POA oversight structures; increased time burden for physicians, nurses, and coders; need to upgrade or purchase new software; and need to collaborate with hospital departments or staff that did not interface directly in the past. The policy was adopted by a majority of other payers, although the list of conditions and payment penalties varies. The HAC-POA policy is invisible to patients; therefore, the presence or lack of unintended consequences to patients cannot be fully assessed at this time. Understanding of policy effects to all stakeholders is important for maximizing its successful implementation and desired impact.

  11. Guideline harmonization and implementation plan for the BETTER trial: Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Family Practice

    PubMed Central

    Rogers, Jess; Manca, Donna; Lang-Robertson, Kelly; Bell, Stephanie; Salvalaggio, Ginetta; Greiver, Michelle; Korownyk, Christina; Klein, Doug; Carroll, June C.; Kahan, Mel; Meuser, Jamie; Buchman, Sandy; Barrett, Rebekah M.; Grunfeld, Eva

    2014-01-01

    Background The aim of the Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Family Practice (BETTER) randomized controlled trial is to improve the primary prevention of and screening for multiple conditions (diabetes, cardiovascular disease, cancer) and some of the associated lifestyle factors (tobacco use, alcohol overuse, poor nutrition, physical inactivity). In this article, we describe how we harmonized the evidence-based clinical practice guideline recommendations and patient tools to determine the content for the BETTER trial. Methods We identified clinical practice guidelines and tools through a structured literature search; we included both indexed and grey literature. From these guidelines, recommendations were extracted and integrated into knowledge products and outcome measures for use in the BETTER trial. End-users (family physicians, nurse practitioners, nurses and dieticians) were engaged in reviewing the recommendations and tools, as well as tailoring the content to the needs of the BETTER trial and family practice. Results In total, 3–5 high-quality guidelines were identified for each condition; from these, we identified high-grade recommendations for the prevention of and screening for chronic disease. The guideline recommendations were limited by conflicting recommendations, vague wording and different taxonomies for strength of recommendation. There was a lack of quality evidence for manoeuvres to improve the uptake of guidelines among patients with depression. We developed the BETTER clinical algorithms for the implementation plan. Although it was difficult to identify high-quality tools, 180 tools of interest were identified. Interpretation The intervention for the BETTER trial was built by integrating existing guidelines and tools, and working with end-users throughout the process to increase the intervention’s utility for practice. Trial registration: ISRCTN07170460 PMID:25077119

  12. Practical Thermal Evaluation Methods For HAC Fire Analysis In Type B Radiaoactive Material (RAM) Packages

    SciTech Connect

    Abramczyk, Glenn; Hensel, Stephen J; Gupta, Narendra K.

    2013-03-28

    Title 10 of the United States Code of Federal Regulations Part 71 for the Nuclear Regulatory Commission (10 CFR Part 71.73) requires that Type B radioactive material (RAM) packages satisfy certain Hypothetical Accident Conditions (HAC) thermal design requirements to ensure package safety during accidental fire conditions. Compliance with thermal design requirements can be met by prototype tests, analyses only or a combination of tests and analyses. Normally, it is impractical to meet all the HAC using tests only and the analytical methods are too complex due to the multi-physics non-linear nature of the fire event. Therefore, a combination of tests and thermal analyses methods using commercial heat transfer software are used to meet the necessary design requirements. The authors, along with his other colleagues at Savannah River National Laboratory in Aiken, SC, USA, have successfully used this 'tests and analyses' approach in the design and certification of several United States' DOE/NNSA certified packages, e.g. 9975, 9977, 9978, 9979, H1700, and Bulk Tritium Shipping Package (BTSP). This paper will describe these methods and it is hoped that the RAM Type B package designers and analysts can use them for their applications.

  13. HAC1 and HAF1 Histone Acetyltransferases Have Different Roles in UV-B Responses in Arabidopsis

    PubMed Central

    Fina, Julieta P.; Masotti, Fiorella; Rius, Sebastián P.; Crevacuore, Franco; Casati, Paula

    2017-01-01

    Arabidopsis has 12 histone acetyltransferases grouped in four families: the GNAT/HAG, the MYST/HAM, the p300/CBP/HAC and the TAFII250/HAF families. We previously showed that ham1 and ham2 mutants accumulated higher damaged DNA after UV-B exposure than WT plants. In contrast, hag3 RNA interference transgenic plants showed less DNA damage and lower inhibition of plant growth by UV-B, and increased levels of UV-B-absorbing compounds. These results demonstrated that HAM1, HAM2, and HAG3 participate in UV-B-induced DNA damage repair and signaling. In this work, to further explore the role of histone acetylation in UV-B responses, a putative function of other acetyltransferases of the HAC and the HAF families was analyzed. Neither HAC nor HAF acetyltrasferases participate in DNA damage and repair after UV-B radiation in Arabidopsis. Despite this, haf1 mutants presented lower inhibition of leaf and root growth by UV-B, with altered expression of E2F transcription factors. On the other hand, hac1 plants showed a delay in flowering time after UV-B exposure and changes in FLC and SOC1 expression patterns. Our data indicate that HAC1 and HAF1 have crucial roles for in UV-B signaling, confirming that, directly or indirectly, both enzymes also have a role in UV-B responses. PMID:28740501

  14. Harmonic statistics

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2017-05-01

    The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their 'public relations' for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford's law, and 1/f noise.

  15. Steps toward harmonization for clinical development of medicines in pediatric ulcerative colitis-a global scientific discussion, part 2: data extrapolation, trial design, and pharmacokinetics.

    PubMed

    Sun, Haihao; Vesely, Richard; Nelson, Robert M; Taminiau, Jan; Szitanyi, Peter; Isaac, Maria; Klein, Agnes; Uzu, Shinobu; Griebel, Donna; Mulberg, Andrew E

    2014-06-01

    To facilitate global drug development, the International Pediatric Inflammatory Bowel Disease Working Group (i-IBD Working Group) discussed data extrapolation, trial design, and pharmacokinetic (PK) considerations for drugs intended to treat pediatric ulcerative colitis (UC), and considered possible approaches toward harmonized drug development. Representatives from the US Food and Drug Administration, European Medicines Agency, Health Canada, and the Pharmaceuticals and Medical Devices Agency of Japan convened monthly to explore existing regulatory approaches, reviewed the results of a literature search, and provided perspectives on pediatric UC drug development based on the available medical literature. Although pediatric UC, when compared with UC in adults, has a similar disease progression and response to intervention, the similarity of the exposure-response relation has not been adequately established. Consequently, clinical endpoints should be selected to optimally assess efficacy in children. The inclusion of a placebo control in pediatric trials to assure assay sensitivity may be appropriate under limited circumstances. In clinical studies, although the drug under investigation could provide possible direct benefit, placebo treatment should present no more than a minor increase over minimal risk to children with UC. Partial extrapolation of efficacy from informative adult studies may be appropriate. Placebo-controlled efficacy trials are scientifically and ethically appropriate for pediatric UC given appropriate patient selection and the use of early escape. Clinical studies in pediatric UC may include initial dose-finding studies and exposure-response modeling followed by an efficacy and safety study to further explore the exposure-response relation.

  16. Guideline harmonization and implementation plan for the BETTER trial: Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Family Practice.

    PubMed

    Campbell-Scherer, Denise; Rogers, Jess; Manca, Donna; Lang-Robertson, Kelly; Bell, Stephanie; Salvalaggio, Ginetta; Greiver, Michelle; Korownyk, Christina; Klein, Doug; Carroll, June C; Kahan, Mel; Meuser, Jamie; Buchman, Sandy; Barrett, Rebekah M; Grunfeld, Eva

    2014-01-01

    The aim of the Building on Existing Tools to Improve Chronic Disease Prevention and Screening in Family Practice (BETTER) randomized controlled trial is to improve the primary prevention of and screening for multiple conditions (diabetes, cardiovascular disease, cancer) and some of the associated lifestyle factors (tobacco use, alcohol overuse, poor nutrition, physical inactivity). In this article, we describe how we harmonized the evidence-based clinical practice guideline recommendations and patient tools to determine the content for the BETTER trial. We identified clinical practice guidelines and tools through a structured literature search; we included both indexed and grey literature. From these guidelines, recommendations were extracted and integrated into knowledge products and outcome measures for use in the BETTER trial. End-users (family physicians, nurse practitioners, nurses and dieticians) were engaged in reviewing the recommendations and tools, as well as tailoring the content to the needs of the BETTER trial and family practice. In total, 3-5 high-quality guidelines were identified for each condition; from these, we identified high-grade recommendations for the prevention of and screening for chronic disease. The guideline recommendations were limited by conflicting recommendations, vague wording and different taxonomies for strength of recommendation. There was a lack of quality evidence for manoeuvres to improve the uptake of guidelines among patients with depression. We developed the BETTER clinical algorithms for the implementation plan. Although it was difficult to identify high-quality tools, 180 tools of interest were identified. The intervention for the BETTER trial was built by integrating existing guidelines and tools, and working with end-users throughout the process to increase the intervention's utility for practice. ISRCTN07170460.

  17. Evidence That Base-pairing Interaction between Intron and mRNA Leader Sequences Inhibits Initiation of HAC1 mRNA Translation in Yeast*

    PubMed Central

    Sathe, Leena; Bolinger, Cheryl; Mannan, M. Amin-ul; Dever, Thomas E.; Dey, Madhusudan

    2015-01-01

    The Hac1 transcription factor in yeast up-regulates a collection of genes that control protein homeostasis. Base-pairing interactions between sequences in the intron and the 5′-untranslated region (5′ UTR) of the HAC1 mRNA represses Hac1 protein production under basal conditions, whereas cytoplasmic splicing of the intron by the Ire1 kinase-endonuclease, activated under endoplasmic reticulum stress conditions, relieves the inhibition and enables Hac1 synthesis. Using a random mutational screen as well as site-directed mutagenesis, we identify point mutations within the 5′ UTR-intron interaction site that derepress translation of the unspliced HAC1 mRNA. We also show that insertion of an in-frame AUG start codon upstream of the interaction site releases the translational block, demonstrating that an elongating ribosome can disrupt the interaction. Moreover, overexpression of translation initiation factor eIF4A, a helicase, enhances production of Hac1 from an mRNA containing an upstream AUG start codon at the beginning of the base-paired region. These results suggest that the major block of translation occurs at the initiation stage. Supporting this interpretation, the point mutations that enhanced Hac1 production resulted in an increased percentage of the HAC1 mRNA associating with polysomes versus free ribosomal subunits. Thus, our results provide evidence that the 5′ UTR-intron interaction represses translation initiation on the unspliced HAC1 mRNA. PMID:26175153

  18. The effect of pioglitazone on aldosterone and cortisol production in HAC15 human adrenocortical carcinoma cells.

    PubMed

    Pan, Zhi-qiang; Xie, Ding; Choudhary, Vivek; Seremwe, Mutsa; Tsai, Ying-Ying; Olala, Lawrence; Chen, Xunsheng; Bollag, Wendy B

    2014-08-25

    Pioglitazone belongs to the class of drugs called thiazolidinediones (TZDs), which are widely used as insulin sensitizers in the treatment of diabetes. A major side effect of TZDs is fluid retention. The steroid hormone aldosterone also promotes sodium and fluid retention; however, the effect of pioglitazone on aldosterone production is controversial. We analyzed the effect of pioglitazone alone and in combination with angiotensin II (AngII) on the late rate-limiting step of adrenocortical steroidogenesis in human adrenocortical carcinoma HAC15 cells. Treatment with pioglitazone for 24 h significantly increased the expression of CYP11B2 and enhanced AngII-induced CYP11B2 expression. Despite the observed changes in mRNA levels, pioglitazone significantly inhibited AngII-induced aldosterone production and CYP11B2 protein levels. On the other hand, pioglitazone stimulated the expression of the unfolded protein response (UPR) marker DDIT3, with this effect occurring at early times and inhibitable by the PPARγ antagonist GW9962. The levels of DDIT3 (CHOP) and phospho-eIF2α (Ser51), a UPR-induced event that inhibits protein translation, were also increased. Thus, pioglitazone promotes CYP11B2 expression but nevertheless inhibits aldosterone production in AngII-treated HAC15 cells, likely by blocking global protein translation initiation through DDIT3 and phospho-eIF2α. In contrast, pioglitazone promoted AngII-induced CYP11B1 expression and cortisol production. Since cortisol enhances lipolysis, this result suggests the possibility that PPARs, activated by products of fatty acid oxidation, stimulate cortisol secretion to promote utilization of fatty acids during fasting. In turn, the ability of pioglitazone to stimulate cortisol production could potentially underlie the effects of this drug on fluid retention.

  19. Presence of PAH or HAC below 900 km in the Titan's stratosphere?

    NASA Astrophysics Data System (ADS)

    Cordier, Daniel; COURS, Thibaud; Rey, Michael; Maltagliati, Luca; Seignovert, Benoit; Biennier, Ludovic

    2016-10-01

    In 2006, during Cassini's 10th flyby of Titan (T10), Bellucci et al. (2009) observed a solar occultation by Titan's atmosphere through the solar port of the Cassini/VIMS instrument. These authors noticed the existence of an unexplained additional absorption superimposed to the CH4 3.3 microns band. Because they were unable to model this absorption with gases, they attributed this intriguing feature to the signature of solid state organic components. Kim et al. (2011) revisited the data collected by Bellucci et al. (2009) and they considered the possible contribution of aerosols formed by hydrocarbon ices. They specifically took into account C2H6, CH4, CH3CN, C5H12 and C6H12 ices. More recently, Maltagliati et al. (2015) analyzed a set of four VIMS solar occultations, corresponding to flybys performed between January 2006 and September 2011 at different latitudes. They confirmed the presence of the 3.3 µm absorption in all occultations and underlined the possible importance of gaseous ethane, which has a strong plateau of absorption lines in that wavelength range. In this work, we show that neither hydrocarbon ices nor molecular C2H6 cannot satisfactorily explain the observed absorption. Our simulations speak in favor of an absorption due to the presence of PAH molecules or HAC in the stratosphere of Titan. PAH have been already considered by Lopes-Puertas et al. (2013) at altitudes larger than ~900 km and tentatively identified in the stratosphere by Maltagliati et al. (2015); PAH and HAC are good candidates for Titan's aerosols precursors.

  20. Discriminating harmonicity

    NASA Astrophysics Data System (ADS)

    Kidd, Gerald; Mason, Christine R.; Brughera, Andrew; Chiu, Chung-Yiu Peter

    2003-08-01

    Simultaneous tones that are harmonically related tend to be grouped perceptually to form a unitary auditory image. A partial that is mistuned stands out from the other tones, and harmonic complexes with different fundamental frequencies can readily be perceived as separate auditory objects. These phenomena are evidence for the strong role of harmonicity in perceptual grouping and segregation of sounds. This study measured the discriminability of harmonicity directly. In a two interval, two alternative forced-choice (2I2AFC) paradigm, the listener chose which of two sounds, signal or foil, was composed of tones that more closely matched an exact harmonic relationship. In one experiment, the signal was varied from perfectly harmonic to highly inharmonic by adding frequency perturbation to each component. The foil always had 100% perturbation. Group mean performance decreased from greater than 90% correct for 0% signal perturbation to near chance for 80% signal perturbation. In the second experiment, adding a masker presented simultaneously with the signals and foils disrupted harmonicity. Both monaural and dichotic conditions were tested. Signal level was varied relative to masker level to obtain psychometric functions from which slopes and midpoints were estimated. Dichotic presentation of these audible stimuli improved performance by 3-10 dB, due primarily to a release from ``informational masking'' by the perceptual segregation of the signal from the masker.

  1. Lactobacillus plantarum HAC01 regulates gut microbiota and adipose tissue accumulation in a diet-induced obesity murine model.

    PubMed

    Park, Soyoung; Ji, Yosep; Jung, Hoe-Yune; Park, Hyunjoon; Kang, Jihee; Choi, Sang-Haeng; Shin, Heuynkil; Hyun, Chang-Kee; Kim, Kyong-Tai; Holzapfel, Wilhelm H

    2017-02-01

    The functional features of Lactobacillus plantarum HAC01 (HAC01), isolated from fermented Korean kimchi, were studied with regard to the fat mass, immunometabolic biomarkers and dysbiosis in a diet-induced obesity (DIO) murine model. L. rhamnosus GG (LGG) served as reference strain and a PBS-treated group as control. The administration of L. plantarum HAC01 resulted in reduction of the mesenteric adipose depot, the conjunctive tissue closely associated with the gastrointestinal tract, where lipid oxidative gene expression was upregulated compared to the control group. Metagenome analysis of intestinal microbiota showed that both strains HAC01 and LGG influenced specific bacterial families such as the Lachnospiraceae and Ruminococcaceae rather than the phyla Firmicutes and Bacteroidetes as a whole. The relative abundance of the Lachnospiraceae (phylum Firmicutes) was significantly higher in both LAB-treated groups than in the control. Comparing the impact of the two Lactobacillus strains on microbial composition in the gut also suggests strain-specific effects. The study emphasises the need for deeper studies into functional specificity of a probiotic organism at the strain level. Alleviation of obesity-associated dysbiosis by modulation of the gut microbiota appears to be associated with "indicator" bacterial taxa such as the family Lachnospiraceae. This may provide further insight into mechanisms basic to the mode of probiotic action against obesity and associated dysbiosis.

  2. A Novel Role for Protein Kinase Kin2 in Regulating HAC1 mRNA Translocation, Splicing, and Translation

    PubMed Central

    Anshu, Ashish; Mannan, M. Amin-ul; Chakraborty, Abhijit; Chakrabarti, Saikat

    2014-01-01

    A signaling network called the unfolded protein response (UPR) resolves the protein-folding defects in the endoplasmic reticulum (ER) from yeasts to humans. In the yeast Saccharomyces cerevisiae, the UPR activation involves (i) aggregation of the ER-resident kinase/RNase Ire1 to form an Ire1 focus, (ii) targeting HAC1 pre-mRNA toward the Ire1 focus that cleaves out an inhibitory intron from the mRNA, and (iii) translation of Hac1 protein from the spliced mRNA. Targeting HAC1 mRNA to the Ire1 focus requires a cis-acting bipartite element (3′BE) located at the 3′ untranslated leader. Here, we report that the 3′BE plays an additional role in promoting translation from the spliced mRNA. We also report that a high dose of either of two paralogue kinases, Kin1 and Kin2, overcomes the defective UPR caused by a mutation in the 3′BE. These results define a novel role for Kin kinases in the UPR beyond their role in cell polarity and exocytosis. Consistently, targeting, splicing, and translation of HAC1 mRNA are substantially reduced in the kin1Δ kin2Δ strain. Furthermore, we show that Kin2 kinase domain itself is sufficient to activate the UPR, suggesting that Kin2 initiates a signaling cascade to ensure an optimum UPR. PMID:25348718

  3. Different functions of the histone acetyltransferase HAC1 gene traced in the model species Medicago truncatula, Lotus japonicus and Arabidopsis thaliana.

    PubMed

    Boycheva, Irina; Vassileva, Valya; Revalska, Miglena; Zehirov, Grigor; Iantcheva, Anelia

    2017-03-01

    In eukaryotes, histone acetyltransferases regulate the acetylation of histones and transcription factors, affecting chromatin structural organization, transcriptional regulation, and gene activation. To assess the role of HAC1, a gene encoding for a histone acetyltransferase in Medicago truncatula, stable transgenic lines with modified HAC1 expression in the model plants M. truncatula, Lotus japonicus, and Arabidopsis thaliana were generated by Agrobacterium-mediated transformation and used for functional analyses. Histochemical, transcriptional, flow cytometric, and morphological analyses demonstrated the involvement of HAC1 in plant growth and development, responses to internal stimuli, and cell cycle progression. Expression patterns of a reporter gene encoding beta-glucuronidase (GUS) fused to the HAC1 promoter sequence were associated with young tissues comprised of actively dividing cells in different plant organs. The green fluorescent protein (GFP) signal, driven by the HAC1 promoter, was detected in the nuclei and cytoplasm of root cells. Transgenic lines with HAC1 overexpression and knockdown showed a wide range of phenotypic deviations and developmental abnormalities, which provided lines of evidence for the role of HAC1 in plant development. Synchronization of A. thaliana root tips in a line with HAC1 knockdown showed the involvement of this gene in the acetylation of two core histones during S phase of the plant cell cycle.

  4. Biocompatibility and Osteogenic Capacity of Periodontal Ligament Stem Cells on nHAC/PLA and HA/TCP Scaffolds.

    PubMed

    He, Huixia; Yu, Jinhua; Cao, Junkai; E, Lingling; Wang, Dongsheng; Zhang, Haizhong; Liu, Hongchen

    2011-01-01

    This study investigated the effects of a newly-developed scaffold, nano-hydroxyapatite/collagen/poly(L-lactide) (nHAC/PLA), on the attachment, proliferation and osteogenic capability of dog periodontal ligament stem cells (PDLSCs) in vitro and in vivo. Hydroxyapatite/tricalcium phosphate (HA/TCP), a commonly used bone substitute, was used as a positive control. PDLSCs isolated from dog molar were incubated in an osteogenic medium to evaluate their osteogenic differentiation in vitro, and then seeded onto nHAC/PLA and HA/TCP scaffolds. In vitro cell attachment, proliferation and differentiation were assessed by scanning electron microscopy (SEM), cell counting, 3-[4,5-dimethythiazol-2-yl]-5-[3-carboxy-phenyl]-2-[4-sulfophenyl]-2H-tetrazolium and alkaline phosphate activity, and reverse transcription-polymerase chain reaction, respectively. Finally, the constructs were implanted subcutaneously into dogs to investigate their osteogenic capacity. After osteogenic induction for 21 days, PDLSCs differentiated into osteogenic lineage, as indicated by the expressions of osteoblastic differentiation genes CoL-I, OCN and OPN mRNA, and the formation of mineral deposits. When seeded onto scaffolds, the cells attached and spread well, and retained their osteogenic phenotypes on both scaffolds. Comparatively, cell number and proliferative viability on nHAC/PLA constructs were greater than those on HA/TCP constructs (P < 0.05). Histological results showed that new bone and osteoid was formed in both groups, and histomorphometric analysis demonstrated that the amount of newly formed bone in the nHAC/PLA group was higher than that in the HA/TCP group (P < 0.05). This study suggests that nHAC/PLA can be used as a potent scaffold for alveolar bone regeneration.

  5. The prevalence of Pediculus humanus capitis in two primary schools of Hacılar, Kayseri.

    PubMed

    Çetinkaya, Ülfet; Hamamcı, Berna; Delice, Safiye; Ercal, Barış Derya; Gücüyetmez, Süheyla; Yazar, Süleyman; Şahin, İzzet

    2011-01-01

    Pediculosis capitis is a worldwide public health concern, and today, head lice are seen in all socio-economic levels. The infestation usually occurs by head-to-head contact and children, primarily girls, aged 3-12 years are mostly affected. In the present study a total of 405 pupils (214 boys and 191 girls) from two pre- and primary schools in the Kayseri-Hacılar region were examined for pediculosis capitis during March 2010. Lice and/or eggs were detected by visual examination of the children's hair. Out of 405 children, 44 (10.9%) were infested with head lice. There were significant differences between the schools and the gender while no significant differences could be found between infestation and child's age, education of the parents, income of the family, housing type, source of water, and the presence or absence of a bathroom. Head lice remain a public health problem and more emphasis should be given to the education of parents regarding their biology and control.

  6. HacA-Independent Functions of the ER Stress Sensor IreA Synergize with the Canonical UPR to Influence Virulence Traits in Aspergillus fumigatus

    PubMed Central

    Richie, Daryl L.; Aimanianda, Vishukumar; Hartl, Lukas; Grahl, Nora; Powers-Fletcher, Margaret V.; Zhang, Minlu; Fuller, Kevin K.; Nierman, William C.; Lu, Long Jason; Latgé, Jean-Paul; Woollett, Laura; Newman, Simon L.; Cramer, Robert A.; Rhodes, Judith C.; Askew, David S.

    2011-01-01

    Endoplasmic reticulum (ER) stress is a condition in which the protein folding capacity of the ER becomes overwhelmed by an increased demand for secretion or by exposure to compounds that disrupt ER homeostasis. In yeast and other fungi, the accumulation of unfolded proteins is detected by the ER-transmembrane sensor IreA/Ire1, which responds by cleaving an intron from the downstream cytoplasmic mRNA HacA/Hac1, allowing for the translation of a transcription factor that coordinates a series of adaptive responses that are collectively known as the unfolded protein response (UPR). Here, we examined the contribution of IreA to growth and virulence in the human fungal pathogen Aspergillus fumigatus. Gene expression profiling revealed that A. fumigatus IreA signals predominantly through the canonical IreA-HacA pathway under conditions of severe ER stress. However, in the absence of ER stress IreA controls dual signaling circuits that are both HacA-dependent and HacA-independent. We found that a ΔireA mutant was avirulent in a mouse model of invasive aspergillosis, which contrasts the partial virulence of a ΔhacA mutant, suggesting that IreA contributes to pathogenesis independently of HacA. In support of this conclusion, we found that the ΔireA mutant had more severe defects in the expression of multiple virulence-related traits relative to ΔhacA, including reduced thermotolerance, decreased nutritional versatility, impaired growth under hypoxia, altered cell wall and membrane composition, and increased susceptibility to azole antifungals. In addition, full or partial virulence could be restored to the ΔireA mutant by complementation with either the induced form of the hacA mRNA, hacA i, or an ireA deletion mutant that was incapable of processing the hacA mRNA, ireA Δ10. Together, these findings demonstrate that IreA has both HacA-dependent and HacA-independent functions that contribute to the expression of traits that are essential for virulence in A. fumigatus

  7. French Jardé's law and European regulation on drug trials: Harmonization and implementation of new rules.

    PubMed

    Deplanque, Dominique; Sénéchal-Cohen, Sophie; Lemaire, François

    2017-02-01

    Jardé's law, concerning research studies in humans, was enacted in March 2012 but did not come into force until November 2016. This delay is largely explained by the adoption of a European regulation on clinical trials on medicinal products that will probably not be applicable until October 2018. In addition to covering the respective areas of the French and European legislation, the round table provided an opportunity to discuss the principal measures that will apply to future research, particularly those concerning the operational procedures of the ethics committees and the national committee for research in humans, as well as measures relating to the management of serious adverse effects, more specifically in phase I studies in subjects not presenting with any disorder. This round table also enabled the formulation of recommendations to better anticipate the practical difficulties that the regulatory changes might engender. Finally, we highlight the numerous challenges in terms of training that these important regulatory changes impose and the absolute necessity to best adapt the restrictions to those that are planned in numerous other European countries so that France remains competitive in terms of clinical research and so that French patients may continue to benefit rapidly from the most innovative treatments.

  8. Clinical trials update from the European Society of Cardiology-Heart Failure meeting 2015: AUGMENT-HF, TITRATION, STOP-HF, HARMONIZE, LION HEART, MOOD-HF, and renin-angiotensin inhibitors in patients with heart and renal failure.

    PubMed

    Pellicori, Pierpaolo; Clark, Andrew L

    2015-09-01

    This article provides an overview on the key trials relevant to the pathophysiology, prevention, and treatment of heart failure (HF) presented at the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) annual meeting held in Seville, Spain in May 2015. Trials reported include AUGMENT-AF (myocardial injections of calcium-alginate hydrogel), a propensity score-matched study of renin-angiotensin system antagonists in patients with HF and severe renal dysfunction, HARMONIZE (sodium zirconium cyclosilicate used to bind potassium), TITRATION, comparing two regimes for introducing LCZ696, STOP-HF, a trial of intramyocardial stromal cell-derived factor-1, MOOD-HF (escitalopram for patients with heart failure and depression), and LION HEART, a trial of intermittent levosimendan therapy. Unpublished reports should be considered as preliminary, since analyses may change in the final publication.

  9. Harmonic engine

    DOEpatents

    Bennett, Charles L [Livermore, CA

    2009-10-20

    A high efficiency harmonic engine based on a resonantly reciprocating piston expander that extracts work from heat and pressurizes working fluid in a reciprocating piston compressor. The engine preferably includes harmonic oscillator valves capable of oscillating at a resonant frequency for controlling the flow of working fluid into and out of the expander, and also preferably includes a shunt line connecting an expansion chamber of the expander to a buffer chamber of the expander for minimizing pressure variations in the fluidic circuit of the engine. The engine is especially designed to operate with very high temperature input to the expander and very low temperature input to the compressor, to produce very high thermal conversion efficiency.

  10. Applicability of equine hydroxyapatite collagen (eHAC) bone blocks for lateral augmentation of the alveolar crest. A histological and histomorphometric analysis in rats.

    PubMed

    Zecha, P J; Schortinghuis, J; van der Wal, J E; Nagursky, H; van den Broek, K C; Sauerbier, S; Vissink, A; Raghoebar, G M

    2011-05-01

    This study assessed the mechanical characteristics, biocompatibility and osteoconductive properties of an equine hydroxyapatite collagen (eHAC) bone block when applied as a bone substitute for lateral augmentation of rat mandible. 96 rats underwent lateral augmentation of the mandible, using two substitute bone blocks (eHAC or Bio-Oss spongiosa) or autologous bone grafts. Signs of inflammation, amount of bone formation and ingrowth of bone into the bone blocks were assessed at 1 and 3 months. eHAC blocks were mechanically rigid and could be fixed firmly and easily. Bio-Oss spongiosa blocks were brittle and fixation was difficult. eHAC and Bio-Oss spongiosa blocks were biocompatible and induced few or no signs of inflammation. Inflammation prevalence between the groups was not statistically different. Bone formation and bone growth into the blocks was significantly higher in eHAC than Bio-Oss spongiosa blocks, but lower than in autologous bone grafts (after 1 and 3 months). Regression analysis showed that the autologous bone graft predicted new bone formation at both time points. The eHAC block was only a predictor at 1 month; a trend was found at 3 months. The application of biodegradable membranes was not related to more bone ingrowth.

  11. Harmonic engine

    DOEpatents

    Bennett, Charles L.; Sewall, Noel; Boroa, Carl

    2014-08-19

    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into of the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. Upon releasing the inlet valve the inlet valve head undergoes a single oscillation past the equilibrium positio to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. Protrusions carried either by the inlet valve head or piston head are used to bump open the inlet valve from the closed position and initiate the single oscillation of the inlet valve head, and protrusions carried either by the outlet valve head or piston head are used to close the outlet valve ahead of the bump opening of the inlet valve.

  12. Regulating unfolded protein response activator HAC1p for production of thermostable raw-starch hydrolyzing α-amylase in Pichia pastoris.

    PubMed

    Huang, Mengmeng; Gao, Yanyun; Zhou, Xiangshan; Zhang, Yuanxing; Cai, Menghao

    2017-03-01

    Unfolded protein response (UPR) usually happens when expressing heterologous proteins in high level, which may help cells to facilitate protein processing. Here, we evaluated the effects of the UPR activator HAC1p on a raw-starch hydrolyzing α-amylase (Gs4j-amyA), so as to improve heterologous production of the enzyme in Pichia pastoris. The gene (amyA) encoding Gs4j-amyA was first codon-optimized and expressed in P. pastoris under the control of the AOX1 promoter. A high gene dosage (12 copies) of amyA facilitated amylase expression which produced an enzyme activity of 305 U/ml. A spliced HAC1 encoding an UPR activator HAC1p was then co-expressed and the dosage effects of HAC1 on amylase expression was investigated. Six copies of HAC1 driven by AOX1 promoter produced a high amylase activity of 2200 U/ml, further increasing by 621%. However, excessive gene dosages driven by the same promoter led to a titration effect of its transcription factors and decreased the amount of amyA transcripts. Thus, constitutive expression of HAC1 by GAP promotor was further involved and Gs4j-amyA activity reached 3700 U/ml finally, which was further increased by 68.2%. Moreover, Gs4j-amyA was glycosylated in P. pastoris which generated higher enzyme activity than that in E. coli. Generally, regulating HAC1p expression by different strategies enhanced amylase production by 11.1 folds, indicating a reference for expression of other proteins in P. pastoris.

  13. Predicting Effects of Corrosion Erosion of High Strength Steel Pipelines Elbow on CO2-Acetic Acid (HAc) Solution

    NASA Astrophysics Data System (ADS)

    Asmara, Y. P.; Ismail, M. F.; Giok Chui, L.; Halimi, Jamiludin

    2016-02-01

    Simultaneously effect of erosion combined with corrosion becomes the most concern in oil and gas industries. It is due to the fast deterioration of metal as effects of solid particles mixed with corrosive environment. There are many corrosion software to investigate possible degradation mechanisms developed by researchers. They are using many combination factors of chemical reactions and physical process. However effects of CO2 and acid on pipelines orientations are still remain uncovered in their simulation. This research will investigate combination effects of CO2 and HAc on corrosion and erosion artificial environmental containing sands particles in 45°, 90° and 180° elbow pipelines. The research used theoretical calculations combined with experiments for verification. The main concerns are to investigate the maximum erosion corrosion rate and maximum shear stress at the surface. Methodology used to calculate corrosion rate are Linear Polarization Resistance (LPR) and weight loss. The results showed that at 45°, erosion rate is the more significant effects in contributing degradation of the metal. The effects of CO2 and HAc gave significant effects when flow rate of the solution are high which reflect synergism effects of solid particles and those chemical compositions.

  14. Ectopic osteogenesis of an injectable nHAC/CSH loaded with blood-acquired mesenchymal progenitor cells in a nude mice model.

    PubMed

    Han, Xue; Wu, Xia; Liu, Hongchen; Wang, Dongsheng; E, Lingling; Zhou, Wei

    2015-01-01

    An injectable bone cement, nHAC/CSH, which consists of nano-hydroxyapatite/collagen (nHAC) and calcium sulphate hemihydrate (CaSO4.½H2O; CSH) was investigated as a tissue-engineered scaffold material with blood-acquired mesenchymal progenitor cells (BMPCs) as seeding cells. An in vitro study on the cytocompatability of nHAC/CSH and an in vivo study on the ectopic bone formation of nHAC/CSH loaded with dBMPCs were both conducted. The dBMPCs morphology, proliferation, differentiation and apoptosis assays were conducted using the direct contact and extract method. The cells tests exhibited normal growth and bioactive function in vitro. Studies in vivo showed that this injectable tissue engineered bone (ITB) formed bone structure in the heterotopic site of nude mice. These findings indicate that the ITB composed of nHAC/CSH and dBMPCs may represent a useful strategy for clinical reconstruction of irregular bone defects.

  15. Development of a novel HAC-based “gain of signal” quantitative assay for measuring chromosome instability (CIN) in cancer cells

    PubMed Central

    Kim, Jung-Hyun; Lee, Hee-Sheung; Lee, Nicholas C. O.; Goncharov, Nikolay V.; Kumeiko, Vadim; Masumoto, Hiroshi; Earnshaw, William C.; Kouprina, Natalay; Larionov, Vladimir

    2016-01-01

    Accumulating data indicates that chromosome instability (CIN) common to cancer cells can be used as a target for cancer therapy. At present the rate of chromosome mis-segregation is quantified by laborious techniques such as coupling clonal cell analysis with karyotyping or fluorescence in situ hybridization (FISH). Recently, a novel assay was developed based on the loss of a non-essential human artificial chromosome (HAC) carrying a constitutively expressed EGFP transgene (“loss of signal” assay). Using this system, anticancer drugs can be easily ranked on by their effect on HAC loss. However, it is problematic to covert this “loss of signal” assay into a high-throughput screen to identify drugs and mutations that increase CIN levels. To address this point, we re-designed the HAC-based assay. In this new system, the HAC carries a constitutively expressed shRNA against the EGFP transgene integrated into human genome. Thus, cells that inherit the HAC display no green fluorescence, while cells lacking the HAC do. We verified the accuracy of this “gain of signal” assay by measuring the level of CIN induced by known antimitotic drugs and added to the list of previously ranked CIN inducing compounds, two newly characterized inhibitors of the centromere-associated protein CENP-E, PF-2771 and GSK923295 that exhibit the highest effect on chromosome instability measured to date. The “gain of signal” assay was also sensitive enough to detect increase of CIN after siRNA depletion of known genes controlling mitotic progression through distinct mechanisms. Hence this assay can be utilized in future experiments to uncover novel human CIN genes, which will provide novel insight into the pathogenesis of cancer. Also described is the possible conversion of this new assay into a high-throughput screen using a fluorescence microplate reader to characterize chemical libraries and identify new conditions that modulate CIN level. PMID:26943579

  16. Poster 7: Could PAH or HAC explain the Titan's stratosphere absorption around 3.4 µm revealed by solar occultations?

    NASA Astrophysics Data System (ADS)

    Cordier, Daniel; Cours, Thibaud; Rey, Michael; Maltagliati, Luca; Seignovert, Benoit; Biennier, Ludovic

    2016-06-01

    In 2006, during Cassini's 10th flyby of Titan (T10), Bellucci et al. (2009) observed a solar occultation by Titan's atmosphere through the solar port of the Cassini/VIMS instrument. These authors noticed the existence of an unexplained additional absorption superimposed to the CH4 3.3 µm band. Because they were unable to model this absorption with gases, they attributed this intriguing feature to the signature of solid state organic components. Kim et al. (2011) revisited the data collected by Bellucci et al. (2009) and they considered the possible contribution of aerosols formed by hydrocarbon ices. They specifically took into account C2H6, CH4, CH3CN, C5H12 and C6H12 ices. More recently, Maltagliati et al. (2015) analyzed a set of four VIMS solar occultations, corresponding to flybys performed between January 2006 and September 2011 at different latitudes. They confirmed the presence of the 3.3 µm absorption in all occultations and underlined the possible importance of gaseous ethane, which has a strong plateau of absorption lines in that wavelength range.In this work, we show that neither hydrocarbon ices nor molecular C2H6 cannot satisfactorily explain the observed absorption. Our simulations speak in favor of an absorption due to the presence of PAH molecules or HAC in the stratosphere of Titan. PAH have been already considered by Lopes-Puertas et al. (2013) at altitudes larger than ˜900 km and tentatively identified in the stratosphere by Maltagliati et al. (2015); PAH and HAC are good candidates for Titan's aerosols precursors.

  17. Validation of phantom-based harmonization for patient harmonization.

    PubMed

    Panetta, Joseph V; Daube-Witherspoon, Margaret E; Karp, Joel S

    2017-07-01

    To improve the precision of multicenter clinical trials, several efforts are underway to determine scanner-specific parameters for harmonization using standardized phantom measurements. The goal of this study was to test the correspondence between quantification in phantom and patient images and validate the use of phantoms for harmonization of patient images. The National Electrical Manufacturers' Association image quality phantom with hot spheres was scanned on two time-of-flight PET scanners. Whole-body [(18) F]-fluorodeoxyglucose (FDG)-PET scans were acquired of subjects on the same systems. List-mode events from spheres (diam.: 10-28 mm) measured in air on each scanner were embedded into the phantom and subject list-mode data from each scanner to create lesions with known uptake with respect to the local background in the phantom and each subject's liver and lung regions, as a proxy to characterize true lesion quantification. Images were analyzed using the contrast recovery coefficient (CRC) typically used in phantom studies and serving as a surrogate for the standardized uptake value used clinically. Postreconstruction filtering (resolution recovery and Gaussian smoothing) was applied to determine if the effect on the phantom images translates equivalently to subject images. Three postfiltering strategies were selected to harmonize the CRCmean or CRCmax values between the two scanners based on the phantom measurements and then applied to the subject images. Both the average CRCmean and CRCmax values for lesions embedded in the lung and liver in four subjects (BMI range 25-38) agreed to within 5% with the CRC values for lesions embedded in the phantom for all lesion sizes. In addition, the relative changes in CRCmean and CRCmax resulting from the application of the postfilters on the subject and phantom images were consistent within measurement uncertainty. Further, the root mean squared percent difference (RMSpd ) between CRC values on the two scanners

  18. Harmonic analysis of homogeneous networks.

    PubMed

    Wolfe, W J; Rothman, J A; Chang, E H; Aultman, W; Ripton, G

    1995-01-01

    We introduce a generalization of mutually inhibitory networks called homogeneous networks. Such networks have symmetric connection strength matrices that are circulant (one-dimensional case) or block circulant with circulant blocks (two-dimensional case). Fourier harmonics provide universal eigenvectors, and we apply them to several homogeneous examples: k-wta, k-cluster, on/center off/surround, and the assignment problem. We also analyze one nonhomogeneous case: the subset-sum problem. We present the results of 10000 trials on a 50-node k-cluster problem and 100 trials on a 25-node subset-sum problem.

  19. Color harmonization for images

    NASA Astrophysics Data System (ADS)

    Tang, Zhen; Miao, Zhenjiang; Wan, Yanli; Wang, Zhifei

    2011-04-01

    Color harmonization is an artistic technique to adjust a set of colors in order to enhance their visual harmony so that they are aesthetically pleasing in terms of human visual perception. We present a new color harmonization method that treats the harmonization as a function optimization. For a given image, we derive a cost function based on the observation that pixels in a small window that have similar unharmonic hues should be harmonized with similar harmonic hues. By minimizing the cost function, we get a harmonized image in which the spatial coherence is preserved. A new matching function is proposed to select the best matching harmonic schemes, and a new component-based preharmonization strategy is proposed to preserve the hue distribution of the harmonized images. Our approach overcomes several shortcomings of the existing color harmonization methods. We test our algorithm with a variety of images to demonstrate the effectiveness of our approach.

  20. A novel mouse model for Down syndrome that harbor a single copy of human artificial chromosome (HAC) carrying a limited number of genes from human chromosome 21.

    PubMed

    Miyamoto, Kenichi; Suzuki, Nobutaka; Sakai, Kosuke; Asakawa, Shuichi; Okazaki, Tsuneko; Kudoh, Jun; Ikeno, Masashi; Shimizu, Nobuyoshi

    2014-04-01

    Down syndrome (DS), also known as Trisomy 21, is the most common chromosome aneuploidy in live-born children and displays a complicated symptom. To date, several kinds of mouse models have been generated to understand the molecular pathology of DS, yet the gene dosage effects and gene(s)-phenotype(s) correlation are not well understood. In this study, we established a novel method to generate a partial trisomy mice using the mouse ES cells that harbor a single copy of human artificial chromosome (HAC), into which a small human DNA segment containing human chromosome 21 genes cloned in a bacterial artificial chromosome (BAC) was recombined. The produced mice were found to maintain the HAC carrying human genes as a mini-chromosome, hence termed as a Trans-Mini-Chromosomal (TMC) mouse, and HAC was transmitted for more than twenty generations independent from endogenous mouse chromosomes. The three human transgenes including cystathionine β-synthase, U2 auxiliary factor and crystalline alpha A were expressed in several mouse tissues with various expression levels relative to mouse endogenous genes. The novel system is applicable to any of human and/or mouse BAC clones. Thus, the TMC mouse carrying a HAC with a limited number of genes would provide a novel tool for studying gene dosage effects involved in the DS molecular pathogenesis and the gene(s)-phenotype(s) correlation.

  1. The bZIP Transcription Factor HAC-1 Is Involved in the Unfolded Protein Response and Is Necessary for Growth on Cellulose in Neurospora crassa

    PubMed Central

    Larrondo, Luis F.

    2015-01-01

    High protein secretion capacity in filamentous fungi requires an extremely efficient system for protein synthesis, folding and transport. When the folding capacity of the endoplasmic reticulum (ER) is exceeded, a pathway known as the unfolded protein response (UPR) is triggered, allowing cells to mitigate and cope with this stress. In yeast, this pathway relies on the transcription factor Hac1, which mediates the up-regulation of several genes required under these stressful conditions. In this work, we identified and characterized the ortholog of the yeast HAC1 gene in the filamentous fungus Neurospora crassa. We show that its mRNA undergoes an ER stress-dependent splicing reaction, which in N. crassa removes a 23 nt intron and leads to a change in the open reading frame. By disrupting the N. crassa hac-1 gene, we determined it to be crucial for activating UPR and for proper growth in the presence of ER stress-inducing chemical agents. Neurospora is naturally found growing on dead plant material, composed primarily by lignocellulose, and is a model organism for the study of plant cell wall deconstruction. Notably, we found that growth on cellulose, a substrate that requires secretion of numerous enzymes, imposes major demands on ER function and is dramatically impaired in the absence of hac-1, thus broadening the range of physiological functions of the UPR in filamentous fungi. Growth on hemicellulose however, another carbon source that necessitates the secretion of various enzymes for its deconstruction, is not impaired in the mutant nor is the amount of proteins secreted on this substrate, suggesting that secretion, as a whole, is unaltered in the absence of hac-1. The characterization of this signaling pathway in N. crassa will help in the study of plant cell wall deconstruction by fungi and its manipulation may result in important industrial biotechnological applications. PMID:26132395

  2. Simple Harmonic Motion in Harmonic Plane Waves.

    ERIC Educational Resources Information Center

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  3. Simple Harmonic Motion in Harmonic Plane Waves.

    ERIC Educational Resources Information Center

    Benumof, Reuben

    1980-01-01

    Discusses the distribution of kinetic and potential energy in transverse and longitudinal waves and examines the transmission of power and momentum. This discussion is intended to aid in understanding the simple harmonic motion of a particle involved in the propagation of a harmonic mechanical plane wave. (HM)

  4. Harmonization of Biodiesel Specifications

    SciTech Connect

    Alleman, T. L.

    2008-02-01

    Worldwide biodiesel production has grown dramatically over the last several years. Biodiesel standards vary across countries and regions, and there is a call for harmonization. For harmonization to become a reality, standards have to be adapted to cover all feedstocks. Additionally, all feedstocks cannot meet all specifications, so harmonization will require standards to either tighten or relax. For harmonization to succeed, the biodiesel market must be expanded with the alignment of test methods and specification limits, not contracted.

  5. MR harmonic quad study

    SciTech Connect

    Yang, M.-J.; /Fermilab

    1995-01-01

    To understand the effect of Main Ring harmonic quadruple correctors. Previous data taken with the harmonic quads did not agree well with the SYNCH calculation. The ultimate goal of this study was to be able to change the harmonic quads and verify the changes in lattice function.

  6. A portable BRCA1-HAC (human artificial chromosome) module for analysis of BRCA1 tumor suppressor function.

    PubMed

    Kononenko, Artem V; Bansal, Ruchi; Lee, Nicholas C O; Grimes, Brenda R; Masumoto, Hiroshi; Earnshaw, William C; Larionov, Vladimir; Kouprina, Natalay

    2014-12-01

    BRCA1 is involved in many disparate cellular functions, including DNA damage repair, cell-cycle checkpoint activation, gene transcriptional regulation, DNA replication, centrosome function and others. The majority of evidence strongly favors the maintenance of genomic integrity as a principal tumor suppressor activity of BRCA1. At the same time some functional aspects of BRCA1 are not fully understood. Here, a HAC (human artificial chromosome) module with a regulated centromere was constructed for delivery and expression of the 90 kb genomic copy of the BRCA1 gene into BRCA1-deficient human cells. A battery of functional tests was carried out to demonstrate functionality of the exogenous BRCA1. In separate experiments, we investigated the role of BRCA1 in maintenance of heterochromatin integrity within a human functional kinetochore. We demonstrated that BRCA1 deficiency results in a specific activation of transcription of higher-order alpha-satellite repeats (HORs) assembled into heterochromatin domains flanking the kinetochore. At the same time no detectable elevation of transcription was observed within HORs assembled into centrochromatin domains. Thus, we demonstrated a link between BRCA1 deficiency and kinetochore dysfunction and extended previous observations that BRCA1 is required to silence transcription in heterochromatin in specific genomic loci. This supports the hypothesis that epigenetic alterations of the kinetochore initiated in the absence of BRCA1 may contribute to cellular transformation.

  7. Pulsed-field gel electrophoresis proficiency testing trials: toward European harmonization of the typing of food and clinical strains of Listeria monocytogenes.

    PubMed

    Félix, Benjamin; Niskanen, Taina; Vingadassalon, Noémie; Dao, Trinh Tam; Asséré, Adrien; Lombard, Bertrand; Brisabois, Anne; Roussel, Sophie

    2013-10-01

    The European Union Reference Laboratory for Listeria monocytogenes (EURL for Lm) coordinates a European network of 35 National Reference Laboratories (NRLs), most of which perform food, environmental, and veterinary Lm strain surveillance in their respective countries. The EURL activities resulted in the recent creation of a database (EURL Lm DB). Typing and related epidemiological data submitted to the EURL Lm DB will be collected and shared by all the NRLs. For a given NRL, the only criterion required in order to submit pulsed-field gel electrophoresis (PFGE) profiles to the database was the successful participation with at least one EURL PFGE and PFGE profile interpretation Proficiency Testing (PT) trial. In this context, the EURL organized a PT trial in 2012 to evaluate the NRL's ability to perform PFGE and profile interpretation. A total of 18 NRLs took part in this study. Upon request from the Food- and Waterborne Diseases and Zoonoses Programme of the European Centre for Disease Prevention and Control, 10 National Public Health Reference Laboratories (NPHLs) also took part in this PT trial. Of the 28 participating laboratories, 16 obtained results classified as "good" or "satisfactory." These 16 laboratories included 10 NRLs (56%) and 6 NPHLs (60%). Of the 22 NRLs and NHPLs that participated in the part of the PT trial related to PFGE profile interpretation, 11 laboratories obtained good results. These 11 laboratories included eight NRLs, which therefore can now submit profiles to the EURL Lm DB. This PT trial provided a valuable opportunity to facilitate and to stimulate the sharing of reproducible PFGE profiles between human and food reference laboratories.

  8. From selective full-length genes isolation by TAR cloning in yeast to their expression from HAC vectors in human cells.

    PubMed

    Kouprina, Natalay; Lee, Nicholas C O; Kononenko, Artem V; Samoshkin, Alexander; Larionov, Vladimir

    2015-01-01

    Transformation-associated recombination (TAR) cloning allows selective isolation of full-length genes and genomic loci as large circular Yeast Artificial Chromosomes (YACs) in yeast. The method has a broad application for structural and functional genomics, long-range haplotyping, characterization of chromosomal rearrangements, and evolutionary studies. In this paper, we describe a basic protocol for gene isolation by TAR as well as a method to convert TAR isolates into Bacterial Artificial Chromosomes (BACs) using a retrofitting vector. The retrofitting vector contains a 3' HPRT-loxP cassette to allow subsequent gene loading into a unique loxP site of the HAC-based (Human Artificial Chromosome) gene delivery vector. The benefit of combining the TAR gene cloning technology with the HAC gene delivery system for gene expression studies is discussed.

  9. Pulsed-field gel electrophoresis, conventional, and molecular serotyping of Listeria monocytogenes from food proficiency testing trials toward an harmonization of subtyping at European level.

    PubMed

    Félix, Benjamin; Dao, Trinh Tam; Grout, Joël; Lombard, Bertrand; Asséré, Adrien; Brisabois, Anne; Roussel, Sophie

    2012-08-01

    The European Union Reference Laboratory for Listeria monocytogenes (EURL for L. monocytogenes) coordinates a European network of 29 National Reference Laboratories (NRLs). Depending on a national decision, NRLs undertake food, environmental, and veterinary L. monocytogenes strain surveillance in their respective countries. In the framework of the PulseNet Europe network, two pulsed-field gel electrophoresis (PFGE) subtyping proficiency testing (PT) trials were carried out in 2003 and 2006. The obtained data showed that PFGE profiles can be compared and exchanged between laboratories. However, no further PT trial had been performed since 2006. In this context, two PT trials were organized by the EURL to evaluate the ability of NRLs to perform conventional serotyping, molecular serotyping and PFGE subtyping. Eleven well-characterized isolates of L. monocytogenes were used: six and nine isolates were tested in 2009 and 2010, respectively. Three isolates were repeated between the two studies. In the 2010 panel, a strain was tested in duplicate, and two strains were related to the same epidemiological group. The strains were analyzed blind in different laboratories (17 in 2009 and 25 in 2010) using (1) their own in-house method for serotyping methods and (2) standardized protocols based on the PulseNet protocol for PFGE. For conventional serotyping, 86.0% in 2009 and 91.0% in 2010 of the serotypes obtained were in agreement with the EURL data. For molecular serotyping, 93.5% of the results in 2009 and 95.2% in 2010 matched the EURL data. For PFGE, 68.9% in 2009 and 81.7% of the combined AscI/ApaI profiles were indistinguishable from the EURL reference profiles. The variations observed could be attributed to slight standardization defaults or, in a few cases, to a failure in DNA extraction. These PT trials provided a valuable opportunity to improve the subtyping ability of NRLs and facilitate exchanges of subtyping data in the future.

  10. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  11. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  12. Chitosan/nHAC/PLGA microsphere vehicle for sustained release of rhBMP-2 and its derived synthetic oligopeptide for bone regeneration.

    PubMed

    Ji, Yanhui; Wang, Mingbo; Liu, Weiqiang; Chen, Changsheng; Cui, Wei; Sun, Tingfang; Feng, Qingling; Guo, Xiaodong

    2016-11-10

    Both of the osteogenic factor and the suitable delivery system in bone tissue engineering are essential for bone regeneration. In this study, we manufactured two kinds of composite vehicles for sustained release of rhBMP-2 and its derived synthetic oligopeptide (Peptide-24, abbreviated as P24) for osteogenesis and bone defect repair. The composite vehicle was based on cross-linked chitosan, nano-hydroxyapatite/collagen (nHAC), and poly (lactide-co-glycolide) acid microsphere. The physicochemical properties of the composite vehicles (abbreviated as CS/nHAC/PLGA-MS) were investigated. The rhBMP-2 and P24 release kinetics from the vehicles were examined and the secondary structure of rhBMP-2 and P24 after 28 days' release process was analyzed. In vitro cell proliferation, osteogenic differentiation and rat calvarial defect repair were evaluated. The results proved that the composite vehicle had favorable compressive strength, elastic modulus, the porosity, and the bulk density. The secondary structures of rhBMP-2 and P24 kept stability during microencapsulation and release process. P24 from the vehicle kept a geared-up release and rhBMP-2 from the vehicle kept a three-stage mode release process. The results of in vitro cell detection showed that the composite vehicle had good biocompatibility and osteoinduction. In vivo rat calvarial defect repair demonstrated that both groups of vehicles with rhBMP2 and P24 exhibited satisfied bone defect repair. This research showed that the composite vehicle could exhibit sustained release of osteogenic factors. CS/nHAC/PLGA-MS loading rhBMP-2 or P24 could be a novel and ideal scaffold for bone regeneration. This article is protected by copyright. All rights reserved.

  13. Harmonic Cancellation System.

    DTIC Science & Technology

    1980-09-01

    memory and those containing memory. - Meory less sys turms ( bou lIinea r ,nfLC nonlinear) have the property that the system OUtput t each instant oL...representations displays the structure of the harmonic distortion products in a different way Equation (2-5) shows that each term in the power series...expansion of the nonlinearity develops a sum * of carriers at (alternate) harmonics of the fundamental frequency and that the fundamental phase term (t) is

  14. Lasing on higher harmonics

    SciTech Connect

    Warren, R.W.

    1990-01-01

    Lasing at short wavelengths with an accelerator of modest energy can only be achieved with a wiggler of short period and high field operating, perhaps, at a high harmonic of the fundamental frequency. We discuss the characteristics of wigglers of this kind, designed to lase with harmonic numbers as large as fifty or so, emphasizing their gain, efficiency, and sensitivity to emittance and energy spread. 5 refs., 3 figs.

  15. Comparison of outcomes of patients with ST-segment elevation myocardial infarction with versus without previous coronary artery bypass grafting (from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI] trial).

    PubMed

    Nikolsky, Eugenia; Mehran, Roxana; Yu, Jennifer; Witzenbichler, Bernhard; Brodie, Bruce R; Kornowski, Ran; Brener, Sorin; Xu, Ke; Dangas, George D; Stone, Gregg W

    2013-05-15

    The present substudy from the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial assessed the outcomes and their relation to different antithrombotic regimens in patients with previous coronary artery bypass grafting (CABG) treated with primary percutaneous coronary intervention. Of 3,599 patients with information regarding a history of CABG, 105 (2.9%) had previously undergone CABG. Of these 105 patients, 46 were randomized to heparin plus a glycoprotein IIb/IIIa inhibitor and 59 to bivalirudin. The patients with versus without previous CABG were less frequently triaged to primary percutaneous coronary intervention (83.8% vs 93.2%, p = 0.0002) and had a longer door-to-balloon time (median 1.9 vs 1.6 hours, p = 0.047), lower rates of final Thrombolysis In Myocardial Infarction flow grade 2 to 3 in the intervened vessel (92.6% vs 97.8%, p = 0.007), and less frequent rates of complete or partial ST-segment resolution (66.3% vs 77.6%, p = 0.019). At 3 years, previous CABG was associated with a significantly greater incidence of major adverse cardiovascular events (36.4% vs 21.4%, p <0.001) owing to greater rates of mortality (11.2% vs 6.7%, p = 0.08), reinfarction (11.6% vs 7.1%, p = 0.09), stroke (5.1% vs 1.8%, p = 0.013), and ischemic target vessel revascularization (23.6% vs 12.9%, p = 0.005). The outcomes did not differ significantly as a function of the antithrombotic regimen. On multivariate analysis, previous CABG was an independent predictor of 3-year ischemic stroke (hazard ratio 3.57, 95% confidence interval 1.09 to 11.66). Intervention on the saphenous vein graft versus the native vessel predicted 3-year major adverse cardiovascular events (hazard ratio 2.69, 95% confidence interval 1.17 to 6.19). In the HORIZONS-AMI trial, previous CABG was associated with a delay to mechanical reperfusion and lower rates of percutaneous coronary intervention and patency of the infarct related vessel along

  16. Harmonizing Optimal Strategy for Treatment of coronary artery diseases--comparison of REDUCtion of prasugrEl dose or POLYmer TECHnology in ACS patients (HOST-REDUCE-POLYTECH-ACS RCT): study protocol for a randomized controlled trial.

    PubMed

    Lee, Joo Myung; Jung, Ji-Hyun; Park, Kyung Woo; Shin, Eun-Seok; Oh, Seok Kyu; Bae, Jang-Whan; Rhew, Jay Young; Lee, Namho; Kim, Dong-Bin; Kim, Ung; Han, Jung-Kyu; Lee, Sang Eun; Yang, Han-Mo; Kang, Hyun-Jae; Koo, Bon-Kwon; Kim, Sanghyun; Cho, Yun Kyeong; Shin, Won-Yong; Lim, Young-Hyo; Rha, Seung-Woon; Kim, Seok-Yeon; Lee, Sung Yun; Kim, Young-Dae; Chae, In-Ho; Cha, Kwang Soo; Kim, Hyo-Soo

    2015-09-15

    Antiplatelet treatment is an important component in optimizing the clinical outcomes after percutaneous coronary intervention (PCI) especially in patients with acute coronary syndrome (ACS). Prasugrel, which is a new P2Y12 inhibitor, has been confirmed as efficacious in a large trial in Western countries, and a similar trial is also to be launched in Asian countries. Although a 60-mg loading dose of prasugrel followed by 10 mg per day should be acceptable, there have been no data regarding the optimal dose in Asian patients. Furthermore, serum levels of prasugrel and the rates of platelet inhibition are known to be higher in Asians than Caucasians with the same dose of the drug. Polymer, a key component of drug-eluting stents (DES), has been suggested as the cause of inflammation leading to late complications, and has driven many companies to develop biodegradable-polymer DES. Currently, there are limited data regarding the head-to-head comparison between BP-BES and the biostable polymer CoCr-EES or the newest platinum-chromium everolimus-eluting stent (PtCr-EES). Furthermore, the polymer issue may be more important in ACS where there is ruptured thrombotic plaque where polymer-induced inflammation may affect the local milieu of the stented artery. Therefore, the present study dedicated only to ACS patients, will offer important information on the optimal prasugrel dose in the Asian population by comparing a 10-mg versus a 5-mg maintenance dose beyond 1 month after PCI, as well as giving important insight into the polymer issue by comparing BP-BES versus biostable-polymer PtCr-EES. Harmonizing Optimal Strategy for Treatment of coronary artery diseases--comparison of REDUCtion of prasugrEl dose or POLYmer TECHnology in ACS patients (HOST-REDUCE-POLYTECH-ACS) trial is a multicenter, randomized and open-label clinical study with a 2 × 2 factorial design, according to the type of stent (PtCr-EES versus BP-BES) and prasugrel maintenance dose (5 mg versus 10 mg), to

  17. Optical harmonic generator

    DOEpatents

    Summers, M.A.; Eimerl, D.; Boyd, R.D.

    1982-06-10

    A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The extraordinary or e directions of the crystal elements are oriented in the integral assembly to be in quadrature (90/sup 0/). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude o and e components. For a third-harmonic generation, the input fundamental wave has o and e components whose amplitudes are in a ratio of 2:1 (o:e reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10/sup 0/. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axeses (o).

  18. Optical harmonic generator

    DOEpatents

    Summers, Mark A.; Eimerl, David; Boyd, Robert D.

    1985-01-01

    A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").

  19. Harmonic uniflow engine

    DOEpatents

    Bennett, Charles L.

    2016-03-22

    A reciprocating-piston uniflow engine includes a harmonic oscillator inlet valve capable of oscillating at a resonant frequency for controlling the flow of working fluid into the engine. In particular, the inlet valve includes an inlet valve head and a spring arranged together as a harmonic oscillator so that the inlet valve head is moveable from an unbiased equilibrium position to a biased closed position occluding an inlet. When released, the inlet valve head undergoes a single oscillation past the equilibrium position to a maximum open position and returns to a biased return position close to the closed position to choke the flow and produce a pressure drop across the inlet valve causing the inlet valve to close. In other embodiments, the harmonic oscillator arrangement of the inlet valve enables the uniflow engine to be reversibly operated as a uniflow compressor.

  20. Harmonic Frequency Lowering

    PubMed Central

    Kirchberger, Martin

    2016-01-01

    A novel algorithm for frequency lowering in music was developed and experimentally tested in hearing-impaired listeners. Harmonic frequency lowering (HFL) combines frequency transposition and frequency compression to preserve the harmonic content of music stimuli. Listeners were asked to make judgments regarding detail and sound quality in music stimuli. Stimuli were presented under different signal processing conditions: original, low-pass filtered, HFL, and nonlinear frequency compressed. Results showed that participants reported perceiving the most detail in the HFL condition. In addition, there was no difference in sound quality across conditions. PMID:26834122

  1. Booster Double Harmonic Setup Notes

    SciTech Connect

    Gardner, C. J.

    2015-02-17

    The motivation behind implementing a booster double harmonic include the reduced transverse space charge force from a reduced peak beam current and reduced momentum spread of the beam, both of which can be achieved from flattening the RF bucket. RF capture and acceleration of polarized protons (PP) is first set up in the single harmonic mode with RF harmonic h=1. Once capture and acceleration have been set up in the single harmonic mode, the second harmonic system is brought on and programmed to operate in concert with the single harmonic system.

  2. RESONANT HARMONIC GENERATION AND NONLINEAR OPTICS.

    DTIC Science & Technology

    OSCILLATORS, *QUANTUM THEORY, *OPTICS, HARMONIC GENERATORS, OSCILLATORS, HARMONIC GENERATORS, OSCILLATORS, HARMONIC GENERATORS, NONLINEAR SYSTEMS, QUARTZ, TOURMALINE , ZINC COMPOUNDS, OXIDES, HYDRATES, NIOBATES, TENSOR ANALYSIS.

  3. A novel HAC1-based dual-luciferase reporter vector for detecting endoplasmic reticulum stress and unfolded protein response in yeast Saccharomyces cerevisiae.

    PubMed

    Fang, Zhijia; Kuang, Xin; Zhang, Youshang; Shi, Ping; Huang, Zhiwei

    2015-05-01

    Unfolded protein response (UPR) is an important cellular phenomenon induced by over-accumulation of unfolded proteins in the endoplasmic reticulum (ER) lumen. ER stress and UPR are implicated in human diseases such as diabetes, atherosclerosis and neurodegenerative diseases. Current methods for measuring ER stress levels and UPR activation usually include cells lysis and other complicated procedures such as reverse transcription-PCR (RT-PCR). These methods typically have low sensitivity and are not suitable for live detection. In this study, we developed a dual-luciferase gene reporter system to monitor UPR activation in live cells of the yeast Saccharomyces cerevisiae by taking advantage of the HAC1 intron and its unconventional splicing-regulation mechanism. We showed that this reporter can be used to monitor UPR in live cells with high sensitivity. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  5. Introducing Simple Harmonic Motion.

    ERIC Educational Resources Information Center

    Roche, John

    2002-01-01

    Explains the origin and significance of harmonic motion which is an important topic that has wide application in the world. Describes the phenomenon by using an auxiliary circle to help illustrate the key relationships between acceleration, displacement, time, velocity, and phase. (Contains 16 references.) (Author/YDS)

  6. Stress in Harmonic Serialism

    ERIC Educational Resources Information Center

    Pruitt, Kathryn Ringler

    2012-01-01

    This dissertation proposes a model of word stress in a derivational version of Optimality Theory (OT) called Harmonic Serialism (HS; Prince and Smolensky 1993/2004, McCarthy 2000, 2006, 2010a). In this model, the metrical structure of a word is derived through a series of optimizations in which the "best" metrical foot is chosen…

  7. Stress in Harmonic Serialism

    ERIC Educational Resources Information Center

    Pruitt, Kathryn Ringler

    2012-01-01

    This dissertation proposes a model of word stress in a derivational version of Optimality Theory (OT) called Harmonic Serialism (HS; Prince and Smolensky 1993/2004, McCarthy 2000, 2006, 2010a). In this model, the metrical structure of a word is derived through a series of optimizations in which the "best" metrical foot is chosen…

  8. Extended range harmonic filter

    NASA Technical Reports Server (NTRS)

    Jankowski, H.; Geia, A. J.; Allen, C. C.

    1973-01-01

    Two types of filters, leaky-wall and open-guide, are combined into single component. Combination gives 10 db or greater additional attenuation to fourth and higher harmonics, at expense of increasing loss of fundamental frequency by perhaps 0.05 to 0.08 db. Filter is applicable to all high power microwave transmitters, but is especially desirable for satellite transmitters.

  9. A Harmonic Motion Experiment

    ERIC Educational Resources Information Center

    Gluck, P.; Krakower, Zeev

    2010-01-01

    We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)

  10. A Harmonic Motion Experiment

    ERIC Educational Resources Information Center

    Gluck, P.; Krakower, Zeev

    2010-01-01

    We present a unit comprising theory, simulation and experiment for a body oscillating on a vertical spring, in which the simultaneous use of a force probe and an ultrasonic range finder enables one to explore quantitatively and understand many aspects of simple and damped harmonic motions. (Contains 14 figures.)

  11. Living with power system harmonics

    SciTech Connect

    Palko, E.

    1992-06-18

    This paper reports the effect of harmonics on electronic equipment in manufacturing plants which was essentially a nonproblem as recently as nine years ago. In years past, harmonics were essentially a problem experienced by electric utility companies, with a relatively few types of industries impressing a serous degree of harmonics onto the utility system. Utilities typically solved their harmonic problems by imposing limits on the amount of harmonics that a customer was permitted to reflect onto the utility system, and assessing heavy financial penalties for noncompliance. Today's electronic equipment creates a problem that feeds on itself: solid-state electronic equipment is a flagrant generator of harmonics, and solid-state equipment is, itself, intolerant of harmonics and is susceptible to malfunction and failure when served from a harmonic-laden power source.

  12. Young children's harmonic perception.

    PubMed

    Costa-Giomi, Eugenia

    2003-11-01

    Harmony and tonality are two of the most difficult elements for young children to perceive and manipulate and are seldom taught in the schools until the end of early childhood. Children's gradual harmonic and tonal development has been attributed to their cumulative exposure to Western tonal music and their increasing experiential knowledge of its rules and principles. Two questions that are relevant to this problem are: (1) Can focused and systematic teaching accelerate the learning of the harmonic/tonal principles that seem to occur in an implicit way throughout childhood? (2) Are there cognitive constraints that make it difficult for young children to perceive and/or manipulate certain harmonic and tonal principles? A series of studies specifically addressed the first question and suggested some possible answers to the second one. Results showed that harmonic instruction has limited effects on children's perception of harmony and indicated that the drastic improvement in the perception of implied harmony noted approximately at age 9 is due to development rather than instruction. I propose that young children's difficulty in perceiving implied harmony stems from their attention behaviors. Older children have less memory constraints and more strategies to direct their attention to the relevant cues of the stimulus. Younger children focus their attention on the melody, if present in the stimulus, and specifically on its concrete elements such as rhythm, pitch, and contour rather than its abstract elements such as harmony and key. The inference of the abstract harmonic organization of a melody required in the perception of implied harmony is thus an elusive task for the young child.

  13. Quaternionic Harmonic Analysis of Texture

    SciTech Connect

    Mason, J.

    2012-10-01

    QHAT uses various functions and data structures native to MATLAB to analyze crystallographic texture information using harmonic functions on the space of rotations represented as normalized quaternions. These harmonic functions generalize the spherical harmonics in three dimensions, and form the basis for the irreducible representations of the four-dimensional rotation group. This allows the basis of harmonic functions to be reduced to linearly independent combinations that satisfy the crystal and sample symmetry point groups.

  14. Harmonization, Trade, and the Environment.

    ERIC Educational Resources Information Center

    Stevens, Candice

    1993-01-01

    Discusses the harmonization of international methods for the development and administration of product standards. Defines the term "harmonization" and discusses the harmonization of environmental policies and purposes involving product standards; environmental regulations on production methods, technologies, and practices; and life-cycle…

  15. Harmonization, Trade, and the Environment.

    ERIC Educational Resources Information Center

    Stevens, Candice

    1993-01-01

    Discusses the harmonization of international methods for the development and administration of product standards. Defines the term "harmonization" and discusses the harmonization of environmental policies and purposes involving product standards; environmental regulations on production methods, technologies, and practices; and life-cycle…

  16. Analysis of crustal structure of Venus utilizing residual Line-of-Sight (LOS) gravity acceleration and surface topography data. A trial of global modeling of Venus gravity field using harmonic spline method

    NASA Technical Reports Server (NTRS)

    Fang, Ming; Bowin, Carl

    1992-01-01

    To construct Venus' gravity disturbance field (or gravity anomaly) with the spacecraft-observer line of site (LOS) acceleration perturbation data, both a global and a local approach can be used. The global approach, e.g., spherical harmonic coefficients, and the local approach, e.g., the integral operator method, based on geodetic techniques are generally not the same, so that they must be used separately for mapping long wavelength features and short wavelength features. Harmonic spline, as an interpolation and extrapolation technique, is intrinsically flexible to both global and local mapping of a potential field. Theoretically, it preserves the information of the potential field up to the bound by sampling theorem regardless of whether it is global or local mapping, and is never bothered with truncation errors. The improvement of harmonic spline methodology for global mapping is reported. New basis functions, a singular value decomposition (SVD) based modification to Parker & Shure's numerical procedure, and preliminary results are presented.

  17. Second harmonic inversion for ultrasound contrast harmonic imaging.

    PubMed

    Pasovic, Mirza; Danilouchkine, Mike; Faez, Telli; van Neer, Paul L M J; Cachard, Christian; van der Steen, Antonius F W; Basset, Olivier; de Jong, Nico

    2011-06-07

    Ultrasound contrast agents (UCAs) are small micro-bubbles that behave nonlinearly when exposed to an ultrasound wave. This nonlinear behavior can be observed through the generated higher harmonics in a back-scattered echo. In past years several techniques have been proposed to detect or image harmonics produced by UCAs. In these proposed works, the harmonics generated in the medium during the propagation of the ultrasound wave played an important role, since these harmonics compete with the harmonics generated by the micro-bubbles. We present a method for the reduction of the second harmonic generated during nonlinear-propagation-dubbed second harmonic inversion (SHI). A general expression for the suppression signals is also derived. The SHI technique uses two pulses, p' and p″, of the same frequency f(0) and the same amplitude P(0) to cancel out the second harmonic generated by nonlinearities of the medium. Simulations show that the second harmonic is reduced by 40 dB on a large axial range. Experimental SHI B-mode images, from a tissue-mimicking phantom and UCAs, show an improvement in the agent-to-tissue ratio (ATR) of 20 dB compared to standard second harmonic imaging and 13 dB of improvement in harmonic power Doppler.

  18. Harmonic multiplication using resonant tunneling

    NASA Technical Reports Server (NTRS)

    Sollner, T. C. L. G.; Brown, E. R.; Goodhue, W. D.; Correa, C. A.

    1988-01-01

    This paper demonstrates the use of resonant-tunneling diodes as varistors for harmonic multiplication. It is shown that efficient odd-harmonic conversion is possible and that even harmonics do not appear because of the antisymmetry of the current-voltage (I-V) curve. It is also shown that, with the proper choice of resonant-tunneling structure and pump amplitude, most of the harmonic output power can be confined to a single odd-harmonic frequency. Fifth-harmonic multiplication was demonstrated with an output at 21.75 GHz and a power conversion efficiency of 0.5 percent, and a fifth-harmonic efficiency of 2.7 percent was achieved in a circuit simulation using an improved I-V curve.

  19. SEI Approach to Harmonization

    DTIC Science & Technology

    2008-07-18

    Osterweil: Little JIL process language • Amescua, Garcia , Sanchez et. al.: Patterns • Others Multimodel Harmonization Builds on Existing Works © 2008...James, A Systems Approach to Process Infrastructure, INCOSE Symposium 2005 [Amescua-Sanchez] Amescua, Antonio, Javier Garcia , Maria-Isabel Sanchez-Segura...Industrial Design Engineering at the Royal College of Art (RCA) in London. [Byrnes –Vasques 07] Byrnes, Paul D. and Renato Chaves Vasques, Integrated

  20. A Improved Transmission System Harmonic Modeling Technique.

    NASA Astrophysics Data System (ADS)

    Akram, Muhammad Fayyaz

    1994-01-01

    The development of a comprehensive approach to the modeling of electric power transmission systems at harmonic frequencies is presented. For harmonic analysis it is not practically possible to model a large transmission system with its neighboring interconnected systems in detail due to computer time and memory limitations. A large number of components of a large system also makes switching studies a recognized problem with respect to the desired accuracy, and required engineering and computer time. Current methods depend on the trial and error approach or the individual analyst's knowledge of the system, which are imprecise and expensive to develop at harmonic frequencies. The approach to solve this problem involves the development of a formal method for dividing large-scale transmission systems into a main study system and a group of external systems. Then, using an efficient and appropriate method of adjoint network sensitivity analysis, the size of the system model is reduced, keeping the same frequency characteristics as that of the original system. This reduction in model size in turn accommodates larger transmission system size and increases the accuracy and computational efficiency. An efficient and accurate method is also presented that determines the relative importance of external system equivalents on the harmonic impedance of a transmission network. The bilinear theorem provides an economical method of determining the appropriate locations for simplification of external systems. Using this technique, the system model error bounds can be fixed and the high error range of the external system equivalent impedance can be reduced. For filter designs, the most important issue of computing harmonic impedance boundaries is improved by using an efficient adjoint network sensitivity analysis. Using this sensitivity analysis an order of critical components is developed. The number of outage contingencies to be analyzed is reduced by a large factor which

  1. Second-harmonic radiating imaging probes and harmonic holography

    NASA Astrophysics Data System (ADS)

    Pu, Ye; Psaltis, Demetri

    2016-10-01

    Compared with other imaging probes such as fluorescent dyes and quantum dots, second-harmonic radiating imaging probes (SHRIMPs) provide a unique ultrafast, coherent optical contrast that is free of photobleaching and emission intermittency. Using the second-harmonic signal emitted from SHRIMPs, harmonic holography achieves threedimensional holographic imaging with a color contrast similar to fluorescence microscopy where the uninterested background scattering is efficiently suppressed by an optical filter. The coherent contrast provided by SHRIMPs also enables imaging through turbid media via digital phase conjugation. Here we review the developments and applications of SHRIMPs and harmonic holography.

  2. Maelstrom Research guidelines for rigorous retrospective data harmonization

    PubMed Central

    Raina, Parminder; Van den Heuvel, Edwin R; Griffith, Lauren E; Craig, Camille; Saliba, Matilda; Doiron, Dany; Stolk, Ronald P; Knoppers, Bartha M; Ferretti, Vincent; Granda, Peter; Burton, Paul

    2017-01-01

    Abstract Background: It is widely accepted and acknowledged that data harmonization is crucial: in its absence, the co-analysis of major tranches of high quality extant data is liable to inefficiency or error. However, despite its widespread practice, no formalized/systematic guidelines exist to ensure high quality retrospective data harmonization. Methods: To better understand real-world harmonization practices and facilitate development of formal guidelines, three interrelated initiatives were undertaken between 2006 and 2015. They included a phone survey with 34 major international research initiatives, a series of workshops with experts, and case studies applying the proposed guidelines. Results: A wide range of projects use retrospective harmonization to support their research activities but even when appropriate approaches are used, the terminologies, procedures, technologies and methods adopted vary markedly. The generic guidelines outlined in this article delineate the essentials required and describe an interdependent step-by-step approach to harmonization: 0) define the research question, objectives and protocol; 1) assemble pre-existing knowledge and select studies; 2) define targeted variables and evaluate harmonization potential; 3) process data; 4) estimate quality of the harmonized dataset(s) generated; and 5) disseminate and preserve final harmonization products. Conclusions: This manuscript provides guidelines aiming to encourage rigorous and effective approaches to harmonization which are comprehensively and transparently documented and straightforward to interpret and implement. This can be seen as a key step towards implementing guiding principles analogous to those that are well recognised as being essential in securing the foundational underpinning of systematic reviews and the meta-analysis of clinical trials. PMID:27272186

  3. Maelstrom Research guidelines for rigorous retrospective data harmonization.

    PubMed

    Fortier, Isabel; Raina, Parminder; Van den Heuvel, Edwin R; Griffith, Lauren E; Craig, Camille; Saliba, Matilda; Doiron, Dany; Stolk, Ronald P; Knoppers, Bartha M; Ferretti, Vincent; Granda, Peter; Burton, Paul

    2017-02-01

    It is widely accepted and acknowledged that data harmonization is crucial: in its absence, the co-analysis of major tranches of high quality extant data is liable to inefficiency or error. However, despite its widespread practice, no formalized/systematic guidelines exist to ensure high quality retrospective data harmonization. To better understand real-world harmonization practices and facilitate development of formal guidelines, three interrelated initiatives were undertaken between 2006 and 2015. They included a phone survey with 34 major international research initiatives, a series of workshops with experts, and case studies applying the proposed guidelines. A wide range of projects use retrospective harmonization to support their research activities but even when appropriate approaches are used, the terminologies, procedures, technologies and methods adopted vary markedly. The generic guidelines outlined in this article delineate the essentials required and describe an interdependent step-by-step approach to harmonization: 0) define the research question, objectives and protocol; 1) assemble pre-existing knowledge and select studies; 2) define targeted variables and evaluate harmonization potential; 3) process data; 4) estimate quality of the harmonized dataset(s) generated; and 5) disseminate and preserve final harmonization products. This manuscript provides guidelines aiming to encourage rigorous and effective approaches to harmonization which are comprehensively and transparently documented and straightforward to interpret and implement. This can be seen as a key step towards implementing guiding principles analogous to those that are well recognised as being essential in securing the foundational underpinning of systematic reviews and the meta-analysis of clinical trials.

  4. Towards automated biomedical ontology harmonization.

    PubMed

    Uribe, Gustavo A; Lopez, Diego M; Blobel, Bernd

    2014-01-01

    The use of biomedical ontologies is increasing, especially in the context of health systems interoperability. Ontologies are key pieces to understand the semantics of information exchanged. However, given the diversity of biomedical ontologies, it is essential to develop tools that support harmonization processes amongst them. Several algorithms and tools are proposed by computer scientist for partially supporting ontology harmonization. However, these tools face several problems, especially in the biomedical domain where ontologies are large and complex. In the harmonization process, matching is a basic task. This paper explains the different ontology harmonization processes, analyzes existing matching tools, and proposes a prototype of an ontology harmonization service. The results demonstrate that there are many open issues in the field of biomedical ontology harmonization, such as: overcoming structural discrepancies between ontologies; the lack of semantic algorithms to automate the process; the low matching efficiency of existing algorithms; and the use of domain and top level ontologies in the matching process.

  5. Why plasma harmonics?

    SciTech Connect

    Ganeev, R A

    2015-09-30

    We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics. (review)

  6. Next generation data harmonization

    NASA Astrophysics Data System (ADS)

    Armstrong, Chandler; Brown, Ryan M.; Chaves, Jillian; Czerniejewski, Adam; Del Vecchio, Justin; Perkins, Timothy K.; Rudnicki, Ron; Tauer, Greg

    2015-05-01

    Analysts are presented with a never ending stream of data sources. Often, subsets of data sources to solve problems are easily identified but the process to align data sets is time consuming. However, many semantic technologies do allow for fast harmonization of data to overcome these problems. These include ontologies that serve as alignment targets, visual tools and natural language processing that generate semantic graphs in terms of the ontologies, and analytics that leverage these graphs. This research reviews a developed prototype that employs all these approaches to perform analysis across disparate data sources documenting violent, extremist events.

  7. RtcB, a novel RNA ligase, can catalyze tRNA splicing and HAC1 mRNA splicing in vivo.

    PubMed

    Tanaka, Naoko; Meineke, Birthe; Shuman, Stewart

    2011-09-02

    RtcB enzymes are novel RNA ligases that join 2',3'-cyclic phosphate and 5'-OH ends. The phylogenetic distribution of RtcB points to its candidacy as a tRNA splicing/repair enzyme. Here we show that Escherichia coli RtcB is competent and sufficient for tRNA splicing in vivo by virtue of its ability to complement growth of yeast cells that lack the endogenous "healing/sealing-type" tRNA ligase Trl1. RtcB also protects yeast trl1Δ cells against a fungal ribotoxin that incises the anticodon loop of cellular tRNAs. Moreover, RtcB can replace Trl1 as the catalyst of HAC1 mRNA splicing during the unfolded protein response. Thus, RtcB is a bona fide RNA repair enzyme with broad physiological actions. Biochemical analysis of RtcB highlights the uniqueness of its active site and catalytic mechanism. Our findings draw attention to tRNA ligase as a promising drug target.

  8. Harmonic generation at high intensities

    SciTech Connect

    Schafer, K.J.; Krause, J.L.; Kulander, K.C.

    1993-06-01

    Atomic electrons subject to intense laser fields can absorb many photons, leading either to multiphoton ionization or the emission of a single, energetic photon which can be a high multiple of the laser frequency. The latter process, high-order harmonic generation, has been observed experimentally using a range of laser wavelengths and intensities over the past several years. Harmonic generation spectra have a generic form: a steep decline for the low order harmonics, followed by a plateau extending to high harmonic order, and finally an abrupt cutoff beyond which no harmonics are discernible. During the plateau the harmonic production is a very weak function of the process order. Harmonic generation is a promising source of coherent, tunable radiation in the XUV to soft X-ray range which could have a variety of scientific and possibly technological applications. Its conversion from an interesting multiphoton phenomenon to a useful laboratory radiation source requires a complete understanding of both its microscopic and macroscopic aspects. We present some recent results on the response of single atoms at intensities relevant to the short pulse experiments. The calculations employ time-dependent methods, which we briefly review in the next section. Following that we discuss the behavior of the harmonics as a function of laser intensity. Two features are notable: the slow scaling of the harmonic intensities with laser intensity, and the rapid variation in the phase of the individual harmonics with respect to harmonic order. We then give a simple empirical formula that predicts the extent of the plateau for a given ionization potential, wavelength and intensity.

  9. Harmonic Series Meets Fibonacci Sequence

    ERIC Educational Resources Information Center

    Chen, Hongwei; Kennedy, Chris

    2012-01-01

    The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

  10. MODEL HARMONIZATION POTENTIAL AND BENEFITS

    EPA Science Inventory

    The IPCS Harmonization Project, which is currently ongoing under the auspices of the WHO, in the context of chemical risk assessment or exposure modeling, does not imply global standardization. Instead, harmonization is thought of as an effort to strive for consistency among appr...

  11. Harmonic Series Meets Fibonacci Sequence

    ERIC Educational Resources Information Center

    Chen, Hongwei; Kennedy, Chris

    2012-01-01

    The terms of a conditionally convergent series may be rearranged to converge to any prescribed real value. What if the harmonic series is grouped into Fibonacci length blocks? Or the harmonic series is arranged in alternating Fibonacci length blocks? Or rearranged and alternated into separate blocks of even and odd terms of Fibonacci length?

  12. MODEL HARMONIZATION POTENTIAL AND BENEFITS

    EPA Science Inventory

    The IPCS Harmonization Project, which is currently ongoing under the auspices of the WHO, in the context of chemical risk assessment or exposure modeling, does not imply global standardization. Instead, harmonization is thought of as an effort to strive for consistency among appr...

  13. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  14. 3D field harmonics

    SciTech Connect

    Caspi, S.; Helm, M.; Laslett, L.J.

    1991-03-30

    We have developed an harmonic representation for the three dimensional field components within the windings of accelerator magnets. The form by which the field is presented is suitable for interfacing with other codes that make use of the 3D field components (particle tracking and stability). The field components can be calculated with high precision and reduced cup time at any location (r,{theta},z) inside the magnet bore. The same conductor geometry which is used to simulate line currents is also used in CAD with modifications more readily available. It is our hope that the format used here for magnetic fields can be used not only as a means of delivering fields but also as a way by which beam dynamics can suggest correction to the conductor geometry. 5 refs., 70 figs.

  15. Nine Principles of Semantic Harmonization

    PubMed Central

    Cunningham, James A.; Van Speybroeck, Michel; Kalra, Dipak; Verbeeck, Rudi

    2016-01-01

    Medical data is routinely collected, stored and recorded across different institutions and in a range of different formats. Semantic harmonization is the process of collating this data into a singular consistent logical view, with many approaches to harmonizing both possible and valid. The broad scope of possibilities for undertaking semantic harmonization do lead however to the development of bespoke and ad-hoc systems; this is particularly the case when it comes to cohort data, the format of which is often specific to a cohort’s area of focus. Guided by work we have undertaken in developing the ‘EMIF Knowledge Object Library’, a semantic harmonization framework underpinning the collation of pan-European Alzheimer’s cohort data, we have developed a set of nine generic guiding principles for developing semantic harmonization frameworks, the application of which will establish a solid base for constructing similar frameworks. PMID:28269840

  16. Nine Principles of Semantic Harmonization.

    PubMed

    Cunningham, James A; Van Speybroeck, Michel; Kalra, Dipak; Verbeeck, Rudi

    2016-01-01

    Medical data is routinely collected, stored and recorded across different institutions and in a range of different formats. Semantic harmonization is the process of collating this data into a singular consistent logical view, with many approaches to harmonizing both possible and valid. The broad scope of possibilities for undertaking semantic harmonization do lead however to the development of bespoke and ad-hoc systems; this is particularly the case when it comes to cohort data, the format of which is often specific to a cohort's area of focus. Guided by work we have undertaken in developing the 'EMIF Knowledge Object Library', a semantic harmonization framework underpinning the collation of pan-European Alzheimer's cohort data, we have developed a set of nine generic guiding principles for developing semantic harmonization frameworks, the application of which will establish a solid base for constructing similar frameworks.

  17. Synchronous Discrete Harmonic Oscillator

    SciTech Connect

    Antippa, Adel F.; Dubois, Daniel M.

    2008-10-17

    We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.

  18. Upper Campanian calciclastic turbidite sequences from the Hacımehmet area (eastern Pontides, NE Turkey): integrated biostratigraphy and microfacies analysis

    NASA Astrophysics Data System (ADS)

    Sari, Bilal; Kandemir, Raif; Özer, Sacit; Walaszczyk, Ireneusz; Görmüş, Muhittin; Demircan, Huriye; Yilmaz, Cemil

    2014-12-01

    The upper Campanian (Cretaceous) of the Hacımehmet area (south of the city of Trabzon; Eastern Pontides) is mainly composed of calciclastic turbidites. The basinal unit of the 119 m thick succession includes thin red pelagic limestone interlayers and conglomerates dominated by volcanic clasts. The overlying upper slope and lower slope units of the sequence consist of an alternation of allochthonous calcarenite/calcirudite beds and pelagic marls and mudstones. Calcarenite/calcirudite beds dominate the upper slope unit of the succession and are composed of transported material, including benthic foraminifers, red algae, bryozoan, crinoid and rudist fragments, inoceramid bivalve prisms and neritic and pelagic carbonate lithoclasts. The occurrence of Helicorbitoides boluensis (Sirel) extracted from the calcarenite/calcirudite beds indicates a Campanian age. Identifiable rudists such as Joufia reticulata Boehm, Bournonia cf. anatolica Ozer, Biradiolites cf. bulgaricus Pamouktchiev and ?Biradiolites sp. from the upper slope unit of the succession indicate a late Campanian- Maastrichtian age. The planktonic foraminifers within the red pelagic limestone beds, marls and mudstones throughout the succession consist mainly of Campanian-Maastrichtian forms and suggest mainly basinal depositional conditions. The presence of Radotruncana cf. calcarata (Cushman) accompanied by Globotruncanita elevata (Brotzen) in the basinal unit of the succession indicates an early late Campanian age for the lower part of the succession. Inoceramid bivalves have been collected from the upper part of the succession. The fauna is dominated by `Inoceramus' tenuilineatus Hall and Meek, 1854 and Cataceramus haldemensis (Giers, 1964); other taxa recognised are: `Inoceramus' algeriensis Heinz, 1932, Platyceramus vanuxemi (Meek and Hayden, 1860), `Inoceramus' cf. nebrascensis Owen, 1852, Cataceramus aff. barabini (Morton, 1834), Cataceramus gandjaensis (Aliev, 1956), and `Inoceramus' sp.; the assemblage

  19. Harmonic Measure of Critical Curves

    SciTech Connect

    Bettelheim, E.; Rushkin, I.; Gruzberg, I.A.; Wiegmann, P.

    2005-10-21

    Fractal geometry of critical curves appearing in 2D critical systems is characterized by their harmonic measure. For systems described by conformal field theories with central charge c{<=}1, scaling exponents of the harmonic measure have been computed by Duplantier [Phys. Rev. Lett. 84, 1363 (2000)] by relating the problem to boundary two-dimensional gravity. We present a simple argument connecting the harmonic measure of critical curves to operators obtained by fusion of primary fields and compute characteristics of the fractal geometry by means of regular methods of conformal field theory. The method is not limited to theories with c{<=}1.

  20. Lattice harmonics expansion revisited

    NASA Astrophysics Data System (ADS)

    Kontrym-Sznajd, G.; Holas, A.

    2017-04-01

    The main subject of the work is to provide the most effective way of determining the expansion of some quantities into orthogonal polynomials, when these quantities are known only along some limited number of sampling directions. By comparing the commonly used Houston method with the method based on the orthogonality relation, some relationships, which define the applicability and correctness of these methods, are demonstrated. They are verified for various sets of sampling directions applicable for expanding quantities having the full symmetry of the Brillouin zone of cubic and non-cubic lattices. All results clearly show that the Houston method is always better than the orthogonality-relation one. For the cubic symmetry we present a few sets of special directions (SDs) showing how their construction and, next, a proper application depend on the choice of various sets of lattice harmonics. SDs are important mainly for experimentalists who want to reconstruct anisotropic quantities from their measurements, performed at a limited number of sampling directions.

  1. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  2. Staging Evaluation and Response Criteria Harmonization (SEARCH) for Childhood, Adolescent and Young Adult Hodgkin Lymphoma (CAYAHL): Methodology statement.

    PubMed

    Flerlage, Jamie E; Kelly, Kara M; Beishuizen, Auke; Cho, Steve; De Alarcon, Pedro A; Dieckmann, Ute; Drachtman, Richard A; Hoppe, Bradford S; Howard, Scott C; Kaste, Sue C; Kluge, Regine; Kurch, Lars; Landman-Parker, Judith; Lewis, Jocelyn; Link, Michael P; McCarten, Kathleen; Punnett, Angela; Stoevesandt, Dietrich; Voss, Stephan D; Wallace, William Hamish; Mauz-Körholz, Christine; Metzger, Monika L

    2017-07-01

    International harmonization of staging evaluation and response criteria is needed for childhood, adolescence, and young adulthood Hodgkin lymphoma. Two Hodgkin lymphoma protocols from cooperative trials in Europe and North America were compared for areas in need of harmonization, and an evidence-based approach is currently underway to harmonize staging and response evaluations with a goal to enhance comparisons, expedite identification of effective therapies, and aid in the approval process for new agents by regulatory agencies. © 2017 Wiley Periodicals, Inc.

  3. Morrey spaces in harmonic analysis

    NASA Astrophysics Data System (ADS)

    Adams, David R.; Xiao, Jie

    2012-10-01

    Through a geometric capacitary analysis based on space dualities, this paper addresses several fundamental aspects of functional analysis and potential theory for the Morrey spaces in harmonic analysis over the Euclidean spaces.

  4. Pythagorean Triples from Harmonic Sequences.

    ERIC Educational Resources Information Center

    DiDomenico, Angelo S.; Tanner, Randy J.

    2001-01-01

    Shows how all primitive Pythagorean triples can be generated from harmonic sequences. Use inductive and deductive reasoning to explore how Pythagorean triples are connected with another area of mathematics. (KHR)

  5. Explaining the harmonic sequence paradox.

    PubMed

    Schmidt, Ulrich; Zimper, Alexander

    2012-05-01

    According to the harmonic sequence paradox, an expected utility decision maker's willingness to pay for a gamble whose expected payoffs evolve according to the harmonic series is finite if and only if his marginal utility of additional income becomes zero for rather low payoff levels. Since the assumption of zero marginal utility is implausible for finite payoff levels, expected utility theory - as well as its standard generalizations such as cumulative prospect theory - are apparently unable to explain a finite willingness to pay. This paper presents first an experimental study of the harmonic sequence paradox. Additionally, it demonstrates that the theoretical argument of the harmonic sequence paradox only applies to time-patient decision makers, whereas the paradox is easily avoided if time-impatience is introduced.

  6. Azimuthal anisotropy: The higher harmonics

    SciTech Connect

    Poskanzer, Arthur M.; STAR Collaboration

    2004-03-12

    We report the first observations of the fourth harmonic (v{sub 4}) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v{sub 4} is about a factor of 10 smaller than v{sub 2}. For the sixth (v{sub 6}) and eighth (v{sub 8}) harmonics upper limits on the magnitudes are reported.

  7. Echo-Enabled Harmonic Generation

    SciTech Connect

    Stupakov, Gennady; /SLAC

    2012-06-28

    A recently proposed concept of the Echo-Enabled Harmonic Generation (EEHG) FEL uses two laser modulators in combination with two dispersion sections to generate a high-harmonic density modulation in a relativistic beam. This seeding technique holds promise of a one-stage soft x-ray FEL that radiates not only transversely but also longitudinally coherent pulses. Currently, an experimental verification of the concept is being conducted at the SLAC National Accelerator Laboratory aimed at the demonstration of the EEHG.

  8. Spherical harmonics in texture analysis

    NASA Astrophysics Data System (ADS)

    Schaeben, Helmut; van den Boogaart, K. Gerald

    2003-07-01

    The objective of this contribution is to emphasize the fundamental role of spherical harmonics in constructive approximation on the sphere in general and in texture analysis in particular. The specific purpose is to present some methods of texture analysis and pole-to-orientation probability density inversion in a unifying approach, i.e. to show that the classic harmonic method, the pole density component fit method initially introduced as a distinct alternative, and the spherical wavelet method for high-resolution texture analysis share a common mathematical basis provided by spherical harmonics. Since pole probability density functions and orientation probability density functions are probability density functions defined on the sphere Ω3⊂ R3 or hypersphere Ω4⊂ R4, respectively, they belong at least to the space of measurable and integrable functions L1( Ωd), d=3, 4, respectively. Therefore, first a basic and simplified method to derive real symmetrized spherical harmonics with the mathematical property of providing a representation of rotations or orientations, respectively, is presented. Then, standard orientation or pole probability density functions, respectively, are introduced by summation processes of harmonic series expansions of L1( Ωd) functions, thus avoiding resorting to intuition and heuristics. Eventually, it is shown how a rearrangement of the harmonics leads quite canonically to spherical wavelets, which provide a method for high-resolution texture analysis. This unified point of view clarifies how these methods, e.g. standard functions, apply to texture analysis of EBSD orientation measurements.

  9. Harmonic analysis of electrical distribution systems

    SciTech Connect

    1996-03-01

    This report presents data pertaining to research on harmonics of electric power distribution systems. Harmonic data is presented on RMS and average measurements for determination of harmonics in buildings; fluorescent ballast; variable frequency drive; georator geosine harmonic data; uninterruptible power supply; delta-wye transformer; westinghouse suresine; liebert datawave; and active injection mode filter data.

  10. Relation of squeezed states between damped harmonic and simple harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Um, Chung-In; Yeon, Kyu-Hwang; George, Thomas F.; Pandey, Lakshmi N.

    1993-01-01

    The minimum uncertainty and other relations are evaluated in the framework of the coherent states of the damped harmonic oscillator. It is shown that the coherent states of the damped harmonic oscillator are the squeezed coherent states of the simple harmonic oscillator. The unitary operator is also constructed, and this connects coherent states with damped harmonic and simple harmonic oscillators.

  11. Asymmetric Gaussian harmonic steering in second-harmonic generation

    NASA Astrophysics Data System (ADS)

    Olsen, M. K.

    2013-11-01

    Intracavity second-harmonic generation is one of the simplest of the quantum optical processes and is well within the expertise of most optical laboratories. It is well understood and characterized, both theoretically and experimentally. We show that it can be a source of continuous-variable asymmetric Gaussian harmonic steering with fields which have a coherent excitation, hence combining the important effects of harmonic entanglement and asymmetric steering in one easily controllable device, adjustable by the simple means of tuning the cavity loss rates at the fundamental and harmonic frequencies. We find that whether quantum steering is available via the standard measurements of the Einstein-Podolsky-Rosen correlations can depend on which quadrature measurements are inferred from output spectral measurements of the fundamental and the harmonic. Altering the ratios of the cavity loss rates can be used to tune the regions where symmetric steering is available, with the results becoming asymmetric over all frequencies as the cavity damping at the fundamental frequency becomes significantly greater than at the harmonic. This asymmetry and its functional dependence on frequency is a potential new tool for experimental quantum information science, with possible utility for quantum key distribution. Although we show the effect here for Gaussian measurements of the quadratures, and cannot rule out a return of the steering symmetry for some class of non-Gaussian measurements, we note here that the system obeys Gaussian statistics in the operating regime investigated and Gaussian inference is at least as accurate as any other method for calculating the necessary correlations. Perhaps most importantly, this system is simpler than any other methods we are aware of which have been used or proposed to create asymmetric steering.

  12. Compact, harmonic multiplying gyrotron amplifiers

    SciTech Connect

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H.

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  13. Tomato heat stress transcription factor HsfB1 represents a novel type of general transcription coactivator with a histone-like motif interacting with the plant CREB binding protein ortholog HAC1.

    PubMed

    Bharti, Kapil; Von Koskull-Döring, Pascal; Bharti, Sanita; Kumar, Pravir; Tintschl-Körbitzer, Angelika; Treuter, Eckardt; Nover, Lutz

    2004-06-01

    In contrast with the class A heat stress transcription factors (HSFs) of plants, a considerable number of HSFs assigned to classes B and C have no evident function as transcription activators on their own. However, in the following article, we provide evidence that tomato (Lycopersicon peruvianum) HsfB1 represents a novel type of coactivator cooperating with class A HSFs (e.g., with tomato HsfA1). Provided the appropriate promoter architecture, the two HSFs assemble into an enhanceosome-like complex, resulting in strong synergistic activation of reporter gene expression. Moreover, HsfB1 also cooperates in a similar manner with other activators, for example, with the ASF1/2 enhancer binding proteins of the 35S promoter of Cauliflower mosaic virus or with yet unidentified activators controlling housekeeping gene expression. By these effects, HsfB1 may help to maintain and/or restore expression of certain viral or housekeeping genes during ongoing heat stress. The coactivator function of HsfB1 depends on a histone-like motif in its C-terminal domain with an indispensable Lys residue in the center (GRGKMMK). This motif is required for recruitment of the plant CREB binding protein (CBP) ortholog HAC1. HsfA1, HsfB1, and HAC1/CBP form ternary complexes in vitro and in vivo with markedly enhanced efficiency in promoter recognition and transcription activation in plant and mammalian (COS7) cells. Using small interfering RNA-mediated knock down of HAC1 expression in Arabidopsis thaliana mesophyll protoplasts, the crucial role for the coactivator function of HsfB1 was confirmed.

  14. Reduction of harmonic pollution in distribution networks

    SciTech Connect

    Lawrance, W.B.; Michalik, G.; Mielczarski, W.; Szczepanik, J.

    1995-12-31

    The paper presents two new schemes of harmonic current reduction in distribution of harmonic current reduction in distribution circuits. The first scheme aims at the reduction of harmonics generated by six pulse bridge rectifiers which are common nonlinear load in industry. The new approach is based on injection of the third harmonic current into the transformer secondary. The current injected is generated in two passive filters connected between the outputs of the bridge and the common point of transformer secondary. The scheme is very effective reducing harmonic distortion in the supply current from 27% to 4--5%. The second scheme presented aims at the reduction of harmonic distortion caused by fluorescent lamp systems. It assumes the installation of a series filter in the neutral conductor. A specially designed filter provides a low impedance path for the first harmonic current and high impedance for higher harmonics. Simulation and laboratory tests show significant reduction of harmonics in the neutral and phase conductors.

  15. Harmonic Nanoparticles for Regenerative Research

    PubMed Central

    Ronzoni, Flavio; Magouroux, Thibaud; Vernet, Remi; Extermann, Jérôme; Crotty, Darragh; Prina-Mello, Adriele; Ciepielewski, Daniel; Volkov, Yuri; Bonacina, Luigi; Wolf, Jean-Pierre; Jaconi, Marisa

    2014-01-01

    In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength. Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed. PMID:24836220

  16. Second Harmonic Breakdown in KSTAR

    SciTech Connect

    Bae, Y. S.; England, A. C.; Kwon, M.; Lee, G. S.

    2007-09-28

    An 84-GHz electron cyclotron heating (ECH) system is being installed on the KSTAR tokamak. KSTAR adopts ECH-assisted start-up for the flexibility and reliability of the KSTAR operation with the plasma breakdown voltage reduced. The available maximum power of the 84 GHz ECH system is presently 500 kW with maximum duration of 2 s. Currently, the second harmonic ECH-assisted start-up is under consideration because a low toroidal field of B{sub T}{approx}1.5 T is desirable for safety and also for the high-beta experiments in the initial operation phase. The studies in this paper are on the effectiveness of the second harmonic breakdown using a 0-D time dependent plasma evolution code and the comparison with the recent DIII-D experimental results on the second harmonic pre-ionization.

  17. Covariant harmonic oscillators: 1973 revisited

    NASA Technical Reports Server (NTRS)

    Noz, M. E.

    1993-01-01

    Using the relativistic harmonic oscillator, a physical basis is given to the phenomenological wave function of Yukawa which is covariant and normalizable. It is shown that this wave function can be interpreted in terms of the unitary irreducible representations of the Poincare group. The transformation properties of these covariant wave functions are also demonstrated.

  18. Combined diplexer and harmonic filter

    NASA Technical Reports Server (NTRS)

    Allen, C. C.

    1973-01-01

    By using two directional filters having circular waveguide filter cavities, diplexing and harmonic filtering functions can be combined into a more compact integrated waveguide assembly. Device is filter which passes power within its pass band limits, but also has a directional characteristic so power transmitted into two-port output waveguide will travel in only one direction.

  19. Second harmonic microscopy of axonemes.

    PubMed

    Odin, Christophe; Heichette, Claire; Chretien, Denis; Le Grand, Yann

    2009-05-25

    We performed Second Harmonic Microscopy of axonemes obtained from sea urchin sperm. Using polarization analysis and a trade-off between signal and photodamage, we were able to determine, for the first time to our knowledge, the nonlinear susceptibility chizxx/chixzx = 1.1+/-0.2 and chizzz/chixzx = 4+/-0.5 of axonemes.

  20. Harmonic undulator radiations with constant magnetic field

    NASA Astrophysics Data System (ADS)

    Jeevakhan, Hussain; Mishra, G.

    2015-01-01

    Harmonic undulators has been analysed in the presence of constant magnetic field along the direction of main undulator field. The spectrum modifications in harmonic undulator radiations and intensity degradation as a function of constant magnetic field magnitude at fundamental and third harmonics have been evaluated with a numerical integration method and generalised Bessel function. The role of harmonic field to overcome the intensity reduction due to constant magnetic field and energy spread in electron beam has also been demonstrated.

  1. Waveguide harmonic damper for klystron amplifier.

    SciTech Connect

    Kang, Y.

    1998-10-27

    A waveguide harmonic damper was designed for removing the harmonic frequency power from the klystron amplifiers of the APS linac. Straight coaxial probe antennas are used in a rectangular waveguide to form a damper. A linear array of the probe antennas is used on a narrow wall of the rectangular waveguide for damping klystron harmonics while decoupling the fundamental frequency in dominent TE{sub 01} mode. The klystron harmonics can exist in the waveguide as waveguide higher-order modes above cutoff. Computer simulations are made to investigate the waveguide harmonic damping characteristics of the damper.

  2. Data harmonization and model performance

    NASA Astrophysics Data System (ADS)

    The Joint Committee on Urban Storm Drainage of the International Association for Hydraulic Research (IAHR) and International Association on Water Pollution Research and Control (IAWPRC) was formed in 1982. The current committee members are (no more than two from a country): B. C. Yen, Chairman (USA); P. Harremoes, Vice Chairman (Denmark); R. K. Price, Secretary (UK); P. J. Colyer (UK), M. Desbordes (France), W. C. Huber (USA), K. Krauth (FRG), A. Sjoberg (Sweden), and T. Sueishi (Japan).The IAHR/IAWPRC Joint Committee is forming a Task Group on Data Harmonization and Model Performance. One objective is to promote international urban drainage data harmonization for easy data and information exchange. Another objective is to publicize available models and data internationally. Comments and suggestions concerning the formation and charge of the Task Group are welcome and should be sent to: B. C. Yen, Dept. of Civil Engineering, Univ. of Illinois, 208 N. Romine St., Urbana, IL 61801.

  3. Axisymmetric generalized harmonic evolution code

    SciTech Connect

    Sorkin, Evgeny

    2010-04-15

    We describe the first axisymmetric numerical code based on the generalized harmonic formulation of the Einstein equations, which is regular at the axis. We test the code by investigating gravitational collapse of distributions of complex scalar field in a Kaluza-Klein spacetime. One of the key issues of the harmonic formulation is the choice of the gauge source functions, and we conclude that a damped-wave gauge is remarkably robust in this case. Our preliminary study indicates that evolution of regular initial data leads to formation both of black holes with spherical and cylindrical horizon topologies. Intriguingly, we find evidence that near threshold for black hole formation the number of outcomes proliferates. Specifically, the collapsing matter splits into individual pulses, two of which travel in the opposite directions along the compact dimension and one which is ejected radially from the axis. Depending on the initial conditions, a curvature singularity develops inside the pulses.

  4. Orthogonality of spherical harmonic coefficients

    NASA Technical Reports Server (NTRS)

    Mcleod, M. G.

    1980-01-01

    Orthogonality relations are obtained for the spherical harmonic coefficients of functions defined on the surface of a sphere. Following a brief discussion of the orthogonality of Fourier series coefficients, consideration is given to the values averaged over all orientations of the coordinate system of the spherical harmonic coefficients of a function defined on the surface of a sphere that can be expressed in terms of Legendre polynomials for the special case where the function is the sum of two delta functions located at two different points on the sphere, and for the case of an essentially arbitrary function. It is noted that the orthogonality relations derived have found applications in statistical studies of the geomagnetic field.

  5. Exact propagators in harmonic superspace

    NASA Astrophysics Data System (ADS)

    Kuzenko, Sergei M.

    2004-10-01

    Within the background field formulation in harmonic superspace for quantum N = 2 super-Yang-Mills theories, the propagators of the matter, gauge and ghost superfields possess a complicated dependence on the SU(2) harmonic variables via the background vector multiplet. This dependence is shown to simplify drastically in the case of an on-shell vector multiplet. For a covariantly constant background vector multiplet, we exactly compute all the propagators. In conjunction with the covariant multi-loop scheme developed in arxiv:hep-th/0302205, these results provide an efficient (manifestly N = 2 supersymmetric) technical setup for computing multi-loop quantum corrections to effective actions in N = 2 supersymmetric gauge theories, including the N = 4 super-Yang-Mills theory.

  6. Harmon Craig (1926-2003)

    NASA Astrophysics Data System (ADS)

    Weiss, Ray

    Harmon Craig, one of the great pioneers of isotope geochemistry died on 14 March after suffering a massive heart attack at his home in La Jolla, California. He was one day shy of his 77th birthday. Through an academic career of more than fifty years, Craig—or simply “Harmon,” as he was known throughout the world of geochemistry—made a remarkable number of fundamental and far-reaching contributions in a wide range of important areas concerned with the chemical and physical processes by which the solid Earth, the oceans, the atmosphere, and the solar system interact. While his research was broad in scope, it was also characterized by a strong emphasis on meticulous field and laboratory work, and on original and insightful interpretations of the resulting observations.

  7. Orthogonality of spherical harmonic coefficients

    NASA Technical Reports Server (NTRS)

    Mcleod, M. G.

    1980-01-01

    Orthogonality relations are obtained for the spherical harmonic coefficients of functions defined on the surface of a sphere. Following a brief discussion of the orthogonality of Fourier series coefficients, consideration is given to the values averaged over all orientations of the coordinate system of the spherical harmonic coefficients of a function defined on the surface of a sphere that can be expressed in terms of Legendre polynomials for the special case where the function is the sum of two delta functions located at two different points on the sphere, and for the case of an essentially arbitrary function. It is noted that the orthogonality relations derived have found applications in statistical studies of the geomagnetic field.

  8. Tailored semiconductors for high-harmonic optoelectronics

    NASA Astrophysics Data System (ADS)

    Sivis, Murat; Taucer, Marco; Vampa, Giulio; Johnston, Kyle; Staudte, André; Naumov, Andrei Yu.; Villeneuve, D. M.; Ropers, Claus; Corkum, P. B.

    2017-07-01

    The advent of high-harmonic generation in gases 30 years ago set the foundation for attosecond science and facilitated ultrafast spectroscopy in atoms, molecules, and solids. We explore high-harmonic generation in the solid state by means of nanostructured and ion-implanted semiconductors. We use wavelength-selective microscopic imaging to map enhanced harmonic emission and show that the generation medium and the driving field can be locally tailored in solids by modifying the chemical composition and morphology. This enables the control of high-harmonic technology within precisely engineered solid targets. We demonstrate customized high-harmonic wave fields with wavelengths down to 225 nanometers (ninth-harmonic order of 2-micrometer laser pulses) and present an integrated Fresnel zone plate target in silicon, which leads to diffraction-limited self-focusing of the generated harmonics down to 1-micrometer spot sizes.

  9. Harmonic oscillator and nuclear pseudospin

    SciTech Connect

    Lisboa, Ronai; Malheiro, Manuel; Castro, Antonio S. de; Alberto, Pedro; Fiolhais, Manuel

    2004-12-02

    A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U, linear in r. Setting either {sigma} = S + V or {delta} = V - S to zero, analytical solutions for bound states are found. The eingenenergies and their nonrelativistic limits are presented and particular cases are discussed, especially the case {sigma} = 0, for which pseudospin symmetry is exact.

  10. Fast generic polar harmonic transforms.

    PubMed

    Hoang, Thai V; Tabbone, Salvatore

    2014-07-01

    Generic polar harmonic transforms have recently been proposed to extract rotation-invariant features from images and their usefulness has been demonstrated in a number of pattern recognition problems. However, direct computation of these transforms from their definition is inefficient and is usually slower than some efficient computation strategies that have been proposed for other methods. This paper presents a number of novel computation strategies to compute these transforms rapidly. The proposed methods are based on the inherent recurrence relations among complex exponential and trigonometric functions used in the definition of the radial and angular kernels of these transforms. The employment of these relations leads to recursive and addition chain-based strategies for fast computation of harmonic function-based kernels. Experimental results show that the proposed method is about 10× faster than direct computation and 5× faster than fast computation of Zernike moments using the q-recursive strategy. Thus, among all existing rotation-invariant feature extraction methods, polar harmonic transforms are the fastest.

  11. Perceptual segregation of a harmonic from a vowel by interaural time difference and frequency proximity.

    PubMed

    Darwin, C J; Hukin, R W

    1997-10-01

    The five experiments reported here examine the conditions under which sounds differing in their interaural time difference (ITD) are segregated for the purposes of perceiving a vowel's identity. Experiment 1 confirms previous findings that (i) a difference in ITD provides only a very weak cue for segregating a vowel's 500-Hz harmonic from the remainder of an isolated vowel; (ii) embedding the harmonic in a series of 500-Hz tones produces some segregation, which is enhanced if the harmonic and the tones differ in ITD from the rest of the vowel; and (iii) when these latter sounds are presented in the same block as isolated vowels, they facilitate segregation of the harmonic by ITD in the isolated vowels. The subsequent experiments show that this last effect, across-trial facilitation, is only produced by sounds which cue both the frequency and the ITD of the harmonic; either alone is insufficient. We also show that: (i) a single cue tone at the frequency of the harmonic is sufficient to facilitate the use of ITD in grouping; (ii) sequential organization by frequency proximity dominates over sequential organization by ITD when simultaneous sound sources are present; and (iii) the effectiveness of a cue tone can be abolished by capturing it into a synchronous harmonic complex. The experiments clarify the conditions under which ITDs contribute to the segregation of simultaneous sounds.

  12. Development of Dry Lubricated Harmonic Drives for Space Applications ('HarmLES')

    NASA Astrophysics Data System (ADS)

    Jansson, Markus; Koenen, Hans; Viviente, Jose-Luis; Tvaruzka, Adam; Merstallinger, Andreas

    2013-09-01

    Today, Harmonic Drive® gears are used in several space flight mechanisms as they provide advantages like zero backlash, a high gear stiffness and a high transmission accuracy. In most cases those gears are used in grease lubricated condition, whereas this is always linked to the risk of outgassing and limits significantly the operational temperature.In order to increase the temperature range, trials to apply solid lubricants to Harmonic Drive® gears, as commonly used for e. g. bearings, were performed. Based on these trials it was found that the gears can be operated even at -269°C. Anyhow, although being used in various cryogenic applications, the reachable lifetime is comparably short. Hence the EU - funded project harmLES was started in 2011 in order to increase the accessible lifetime by developing a new Harmonic Drive® gear type. This activity is based on an integrated approach covering gear design, materials and coating.

  13. Harmonic generation in the generalized Sagdeev pseudopotential

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.

    2017-09-01

    In this paper, we study the nonlinear harmonic generation effect in different oscillator models. For weakly nonlinear systems, we use the generalized forced Korteweg de Vries Burgers (KdVB) and modified KdVB (mKdVB) models in order to classify three fundamentally different harmonic structures in a nonlinear dynamical system. The first is called the internal harmonic structure which exists due to the self oscillation of the system in the absence of dissipation effect and is shown to follow either relations of nf or (2n - 1)f depending on the symmetry of oscillator potential in which n is an integer number and f is the fundamental frequency which is exactly obtained for the Helmholtz oscillator. The second structure is the resonant harmonics which appears in the presence of damping and follows the harmonic structure nf0 in which f0 is the linear resonance frequency. Finally, the last harmonic structure appears in the presence of dissipation and external periodic forcing effects which we call the external harmonic pattern. It is shown that the external harmonic pattern, in which f1 is the driving frequency, always follows the nf1 rule regardless of the potential symmetry. We then extend our analysis to study the harmonic generation in the fully nonlinear generalized Sagdeev potential for real plasmas with isothermal and adiabatic ion fluids and investigate the effects of different plasma parameters such as the fractional ion temperature and normalized ion acoustic speed on all three kinds of harmonic generation.

  14. Fast Harmonic Splines and Parameter Choice Methods

    NASA Astrophysics Data System (ADS)

    Gutting, Martin

    2017-04-01

    Solutions to boundary value problems in geoscience where the boundary is the Earth's surface are constructed in terms of harmonic splines. These are localizing trial functions that allow regional modeling or the improvement of a global model in a part of the Earth's surface. Some cases of the occurring kernels can be equipped with a fast matrix-vector multiplication using the fast multipole method (FMM). The main idea of the fast multipole algorithm consists of a hierarchical decomposition of the computational domain into cubes and a kernel approximation for the more distant points. The numerical effort of the matrix-vector multiplication becomes linear in reference to the number of points for a prescribed accuracy of the kernel approximation. This fast spline approximation which also allows the treatment of noisy data requires the choice of a smoothing parameter. We investigate several methods to (ideally automatically) choose this parameter with and without prior knowledge of the noise level. However, in order to keep a fast solution algorithm we do no longer have access to the whole matrix or e.g. its singular values whose computation requires a much larger numerical effort. This must be reflected by the parameter choice methods. Therefore, in some cases a further approximation is necessary. The performance of these methods is considered for different types of noise in a large simulation study with applications to gravitational field modeling as well as to boundary value problems.

  15. High-harmonic spectroscopy of aligned molecules

    NASA Astrophysics Data System (ADS)

    Yun, Hyeok; Yun, Sang Jae; Lee, Gae Hwang; Nam, Chang Hee

    2017-01-01

    High harmonics emitted from aligned molecules driven by intense femtosecond laser pulses provide the opportunity to explore the structural information of molecules. The field-free molecular alignment technique is an expedient tool for investigating the structural characteristics of linear molecules. The underlying physics of field-free alignment, showing the characteristic revival structure specific to molecular species, is clearly explained from the quantum-phase analysis of molecular rotational states. The anisotropic nature of molecules is shown from the harmonic polarization measurement performed with spatial interferometry. The multi-orbital characteristics of molecules are investigated using high-harmonic spectroscopy, applied to molecules of N2 and CO2. In the latter case the two-dimensional high-harmonic spectroscopy, implemented using a two-color laser field, is applied to distinguish harmonics from different orbitals. Molecular high-harmonic spectroscopy will open a new route to investigate ultrafast dynamics of molecules.

  16. Harmonics and Resonance Issues with Wind Plants

    SciTech Connect

    Bradt, M.; Badrzadeh, Babak; Camm, E H; Castillo, Nestor; Mueller, David; Siebert, T.; Schoene, Jens; Smith, Travis M; Starke, Michael R; Walling, R.

    2011-01-01

    Wind plants are susceptible to lightly-damped resonances which can attract and amplify ambient grid harmonic distortion and magnify wind turbine harmonic generation. Long-accepted harmonic modeling assumptions and practices are not appropriate for wind plants. VSCs are not ideal current sources and grid impedance is important. Attention to modeling detail and thorough evaluation over range of conditions is critical to meaningful analysis. In general, wind turbines are very slight sources of harmonics. Most harmonic issues are a result of resonance, caused by capacitor banks (for reactive power compensation) or from the extensive underground cabling in a collector system. Converter controls instability can be exacerbated by power system resonances. In some cases this has caused severe voltage distorDon and other problems. The IEEE 519 recommended guidelines are very restrictive. I recommend that they are used to resolve serious harmonic issues, and not to create petty problems.

  17. Symmetries of coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1993-01-01

    It is shown that the system of two coupled harmonic oscillators possesses many interesting symmetries. It is noted that the symmetry of a single oscillator is that of the three-parameter group Sp(2). Thus two uncoupled oscillator exhibits a direct product of two Sp(2) groups, with six parameters. The coupling can be achieved through a rotation in the two-dimensional space of two oscillator coordinates. The closure of the commutation relations for the generators leads to the ten-parameter group Sp(4) which is locally isomorphic to the deSitter group O(3,2).

  18. Polarization-fan high-order harmonics

    NASA Astrophysics Data System (ADS)

    Fleischer, Avner; Bordo, Eliyahu; Kfir, Ofer; Sidorenko, Pavel; Cohen, Oren

    2017-02-01

    We predict high-order harmonics in which the polarization within the spectral bandwidth of each harmonic varies with frequency continuously and significantly. For example, the interaction of counter-rotating circularly-polarized bichromatic drivers having close central frequencies with isotropic gas leads to the emission of polarization-fan harmonics where each harmonic in the spectrum has the following property: it is nearly circularly-polarized in one tail of the harmonic peak, linear in the center of the peak and nearly circular with the opposite helicity in the opposite tail. Also, we show that polarization-fan high harmonics with modulated ellipticity are obtained when elliptical drivers are used. Polarization-fan harmonics are obtained as a result of multiple (at least two) head-on recollisions of electrons with their parent ions occurring from different angles in a two-dimensional plane. The use of bichromatic drivers with close central frequencies largely preserves the single-cycle, single-atom and macroscopic physics of ‘ordinary’ high harmonic generation, where both the driver and high harmonics are linearly polarized. Thus, it should offer several attracting features, including (i) a direct route for extending the maximal photon energy of observed helical high harmonics to keV by using bichromatic drivers only in the mid-IR region and (ii) utilizing phase matching methods that were developed for ‘ordinary’ high harmonic generation driven by quasi-monochromatic pulses (e.g. pressure tuning phase matching). These polarization-fan harmonics may be utilized for exploring non-repetitive ultrafast chiral phenomena, e.g. dynamics of magnetic domains, in a single shot.

  19. The harmonic oscillator behind all aberrations

    SciTech Connect

    Wolf, Kurt Bernardo

    2010-12-23

    The group-theoretical structure of the harmonic oscillator appears in many guises. Originally developed by Marcos Moshinsky among several others for applications in nuclear physics, we point out here that the harmonic oscillator structure appears in aberrations of geometric optics, particularly in their classification by rank, symplectic spin and weight. And further, the finite harmonic oscillator appears again in the nonlinear transformations of finite Hamiltonian systems, when applied to the parallel processing of signals.

  20. Harmonic generation in magnetized quantum plasma

    SciTech Connect

    Kumar, Punit; Singh, Abhisek Kumar; Singh, Shiv

    2016-05-06

    A study of second harmonic generation by propagation of a linearly polarized electromagnetic wave through homogeneous high density quantum plasma in the presence of transverse magnetic field. The nonlinear current density and dispersion relations for the fundamental and second harmonic frequencies have been obtained using the recently developed quantum hydrodynamic (QHD) model. The effect of quantum Bohm potential, Fermi pressure and the electron spin have been taken into account. The second harmonic is found to be less dispersed than the first.

  1. Killing vector fields and harmonic superfield theories

    SciTech Connect

    Groeger, Josua

    2014-09-15

    The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.

  2. Killing vector fields and harmonic superfield theories

    NASA Astrophysics Data System (ADS)

    Groeger, Josua

    2014-09-01

    The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.

  3. Global Harmonization of Comparator Products for Bioequivalence Studies.

    PubMed

    Gwaza, Luther; Gordon, John; Leufkens, Hubert; Stahl, Matthias; García-Arieta, Alfredo

    2017-05-01

    Comparator products should be the products that were shown to be safe and efficacious in pivotal clinical trials to ensure prescribability of generics. The use of a common comparator ensures switchability between generics. The selection of the comparator is a national responsibility and may be different between countries. This paper discusses the current recommendations on selection of comparators, the associated problems, and the possibility of harmonization. Most countries follow the World Health Organization (WHO) recommendations for selecting comparator products and require the comparator product to be obtained from their national markets to ensure switchability between the local comparator and their generics. These recommendations are only feasible in the few countries where the repetition of the bioequivalence study is economically feasible, but they are impracticable in all other countries. Furthermore, the exclusive use of the local comparator to ensure switchability is ethically and scientifically questionable. The innovator product from well-regulated markets should be the global comparator. This harmonization is feasible as the concept already applies in the WHO prequalification program. It is ineffectual to harmonize only the requirements for performing bioequivalence studies, if such a study has to be repeated for every single country simply because of the different comparator products.

  4. Second-harmonic optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-05-01

    Second-harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical responses of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second-harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second-harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second-harmonic generation on molecular and tissue structures, this technique imparts contrast and resolution enhancement to conventional optical coherence tomography.

  5. A neural network model of harmonic detection

    NASA Astrophysics Data System (ADS)

    Lewis, Clifford F.

    2003-04-01

    Harmonic detection theories postulate that a virtual pitch is perceived when a sufficient number of harmonics is present. The harmonics need not be consecutive, but higher harmonics contribute less than lower harmonics [J. Raatgever and F. A. Bilsen, in Auditory Physiology and Perception, edited by Y. Cazals, K. Horner, and L. Demany (Pergamon, Oxford, 1992), pp. 215-222 M. K. McBeath and J. F. Wayand, Abstracts of the Psychonom. Soc. 3, 55 (1998)]. A neural network model is presented that has the potential to simulate this operation. Harmonics are first passed through a bank of rounded exponential filters with lateral inhibition. The results are used as inputs for an autoassociator neural network. The model is trained using harmonic data for symphonic musical instruments, in order to test whether it can self-organize by learning associations between co-occurring harmonics. It is shown that the trained model can complete the pattern for missing-fundamental sounds. The Performance of the model in harmonic detection will be compared with experimental results for humans.

  6. Ultrafast adiabatic second harmonic generation

    NASA Astrophysics Data System (ADS)

    Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim

    2017-03-01

    We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.

  7. Ultrafast adiabatic second harmonic generation.

    PubMed

    Dahan, Asaf; Levanon, Assaf; Katz, Mordechai; Suchowski, Haim

    2017-03-01

    We introduce a generalization of the adiabatic frequency conversion method for an efficient conversion of ultrashort pulses in the full nonlinear regime. Our analysis takes into account dispersion as well as two-photon processes and Kerr effect, allowing complete analysis of any three waves with arbitrary phase mismatched design and any nonlinear optical process. We use this analysis to design an efficient and robust second harmonic generation, the most widely used nonlinear process for both fundamental and applied research. We experimentally show that such design not only allows for very efficient conversion of various of ultrashort pulses, but is also very robust to variations in the parameters of both the nonlinear crystal and the incoming light. These include variation of more than 100 °C in the crystal temperature, a wide bandwidth of up to 75 nm and a chirp variation of 300 fs to 3.5 ps of the incoming pulse. Also, we show the dependency of the adiabatic second harmonic generation design on the pump intensity and the crystal length. Our study shows that two photon absorption plays a critical role in such high influence nonlinear dynamics, and that it must be considered in order to achieve agreement with experimental results.

  8. Neural correlates of processing harmonic expectancy violations in children and adolescents with OCD.

    PubMed

    Buse, Judith; Roessner, Veit

    2016-01-01

    It has been suggested that patients with obsessive-compulsive disorder (OCD) exhibit enhanced awareness of embedded stimulus patterns as well as enhanced allocation of attention towards unexpected stimuli. Our study aimed at investigating these OCD characteristics by running the harmonic expectancy violation paradigm in 21 boys with OCD and 29 healthy controls matched for age, gender and IQ during a functional magnetic resonance imaging (fMRI) scan. Each trial consisted of a chord sequence in which the first four chords induced a strong expectancy for a harmonic chord at the next position. In 70% of the trials the fifth chord fulfilled this expectancy (harmonic condition), while in 30% the expectancy was violated (disharmonic condition). Overall, the harmonic condition elicited blood-oxygen-level dependent (BOLD) activation in the auditory cortex, while during the disharmonic condition the precuneus, the auditory cortex, the medial frontal gyrus, the premotor cortex, the lingual gyrus, the inferior frontal gyrus and the superior frontal gyrus were activated. In a cluster extending from the right superior temporal gyrus to the inferior frontal gyrus, boys with OCD exhibited increased activation compared to healthy controls in the harmonic condition and decreased activation in the disharmonic condition. Our findings might indicate that patients with OCD are excessively engaged in processing the implicit structure embedded in music stimuli, but they speak against the suggestion that OCD is associated with a misallocation of attention towards the processing of unexpected stimuli.

  9. Neural correlates of processing harmonic expectancy violations in children and adolescents with OCD

    PubMed Central

    Buse, Judith; Roessner, Veit

    2015-01-01

    It has been suggested that patients with obsessive–compulsive disorder (OCD) exhibit enhanced awareness of embedded stimulus patterns as well as enhanced allocation of attention towards unexpected stimuli. Our study aimed at investigating these OCD characteristics by running the harmonic expectancy violation paradigm in 21 boys with OCD and 29 healthy controls matched for age, gender and IQ during a functional magnetic resonance imaging (fMRI) scan. Each trial consisted of a chord sequence in which the first four chords induced a strong expectancy for a harmonic chord at the next position. In 70% of the trials the fifth chord fulfilled this expectancy (harmonic condition), while in 30% the expectancy was violated (disharmonic condition). Overall, the harmonic condition elicited blood-oxygen-level dependent (BOLD) activation in the auditory cortex, while during the disharmonic condition the precuneus, the auditory cortex, the medial frontal gyrus, the premotor cortex, the lingual gyrus, the inferior frontal gyrus and the superior frontal gyrus were activated. In a cluster extending from the right superior temporal gyrus to the inferior frontal gyrus, boys with OCD exhibited increased activation compared to healthy controls in the harmonic condition and decreased activation in the disharmonic condition. Our findings might indicate that patients with OCD are excessively engaged in processing the implicit structure embedded in music stimuli, but they speak against the suggestion that OCD is associated with a misallocation of attention towards the processing of unexpected stimuli. PMID:26900566

  10. Imaging with Second-Harmonic Generation Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hsieh, Chia-Lung

    Second-harmonic generation nanoparticles show promise as imaging probes due to their coherent and stable signal with a broad flexibility in the choice of excitation wavelength. In this thesis, we developed and demonstrated barium titanate nanoparticles as second-harmonic radiation imaging probes. We studied the absolute second-harmonic generation efficiency of the nanoparticles on single-particle level. The polarization dependent second-harmonic signal of single nanoparticles was studied in detail. From the measured polar response, we were able to find the orientation of the nanoparticle. We developed a biochemical interface for using the second-harmonic nanoprobes as biomarkers, including in vitro cellular imaging and in vivo live animal imaging. The nanoparticles were surface functionalized with primary amine groups for stable colloidal dispersion. We achieved specific labeling of the second-harmonic nanoprobes via immunostaining where the antibodies were covalently conjugated onto the nanoparticles. We observed no toxicity of the functionalized nanoparticles to biological cells. The coherent second-harmonic signal radiated from the nanoparticles offers opportunities for new imaging techniques. Using interferometric detection, namely harmonic holography, both amplitude and phase of the second-harmonic field can be captured. Through digital beam propagation, three-dimensional field distribution, reflecting three-dimensional distribution of the nanoparticles, can be reconstructed. We achieved a scan-free three-dimensional imaging of nanoparticles in biological cells with sub-micron spatial resolution by using the harmonic holographic microscope. We further exploited the coherent second-harmonic signal for imaging through scattering media by performing optical phase conjugation of the second-harmonic signal. We demonstrated an all-digital optical phase conjugation of the second-harmonic signal originated from a nanoparticle by combining harmonic holography and

  11. Impact of stray capacitance on hvdc harmonics

    SciTech Connect

    Larsen, E.V.; Sublich, M.; Kapoor, S.C.

    1989-01-01

    Recent experience suggests that a new approach is needed to determining harmonic generation from hvdc converters for the purpose of telephone interference evaluation. This paper presents simulation results showing the effect on harmonic generation of stray capacitances inherent to hvdc converters. These simulation results illustrate the basic characteristics of the phenomenon, which agree qualitatively with field experience.

  12. Sunspots and Their Simple Harmonic Motion

    ERIC Educational Resources Information Center

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  13. Higher Harmonics in Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Jeon, Sangyong

    2013-03-01

    As the QGP expands and cools, it carries much information on its creation and evolution imprinted on the patterns of higher harmonic flow. In this proceeding we report on the progress in simulating and understanding the higher harmonics by the McGill group using the 3+1D event-by-event viscous hydrodynamics simulation suite named MUSIC.

  14. Dynamics and control of instrumented harmonic drives

    NASA Technical Reports Server (NTRS)

    Kazerooni, H.; Ellis, S. R. (Principal Investigator)

    1995-01-01

    Since torque in harmonic drives is transmitted by a pure couple, harmonic drives do not generate radial forces and therefore can be instrumented with torque sensors without interference from radial forces. The installation of torque sensors on the stationary component of harmonic drives (the Flexipline cup in this research work) produce backdrivability needed for robotic and telerobotic compliant maneuvers. Backdrivability of a harmonic drive, when used as torque increaser, means that the output shaft can be rotated via finite amount of torque. A high ratio harmonic drive is non-backdrivable because its output shaft cannot be turned by applying a torque on it. This article first develops the dynamic behavior of a harmonic drive, in particular the non-backdrivability, in terms of a sensitivity transfer function. The instrumentation of the harmonic drive with torque sensor is then described. This leads to a description of the control architecture which allows modulation of the sensitivity transfer function within the limits established by the closed-loop stability. A set of experiments on an active hand controller, powered by a DC motor coupled to an instrumented harmonic drive, is given to exhibit this method's limitations.

  15. Sunspots and Their Simple Harmonic Motion

    ERIC Educational Resources Information Center

    Ribeiro, C. I.

    2013-01-01

    In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

  16. Harmonic oscillator states in aberration optics

    NASA Technical Reports Server (NTRS)

    Wolf, Kurt Bernardo

    1993-01-01

    The states of the three-dimensional quantum harmonic oscillator classify optical aberrations of axis-symmetric systems due to the isomorphism between the two mathematical structures. Cartesian quanta and angular momentum classifications have their corresponding aberration classifications. The operation of concatenation of optical elements introduces a new operation between harmonic oscillator states.

  17. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  18. Dynamics and control of instrumented harmonic drives

    NASA Technical Reports Server (NTRS)

    Kazerooni, H.; Ellis, S. R. (Principal Investigator)

    1995-01-01

    Since torque in harmonic drives is transmitted by a pure couple, harmonic drives do not generate radial forces and therefore can be instrumented with torque sensors without interference from radial forces. The installation of torque sensors on the stationary component of harmonic drives (the Flexipline cup in this research work) produce backdrivability needed for robotic and telerobotic compliant maneuvers. Backdrivability of a harmonic drive, when used as torque increaser, means that the output shaft can be rotated via finite amount of torque. A high ratio harmonic drive is non-backdrivable because its output shaft cannot be turned by applying a torque on it. This article first develops the dynamic behavior of a harmonic drive, in particular the non-backdrivability, in terms of a sensitivity transfer function. The instrumentation of the harmonic drive with torque sensor is then described. This leads to a description of the control architecture which allows modulation of the sensitivity transfer function within the limits established by the closed-loop stability. A set of experiments on an active hand controller, powered by a DC motor coupled to an instrumented harmonic drive, is given to exhibit this method's limitations.

  19. The Harmonic Series Diverges Again and Again

    ERIC Educational Resources Information Center

    Kifowit, Steven J.; Stamps, Terra A.

    2006-01-01

    The harmonic series is one of the most celebrated infinite series of mathematics. A quick glance at a variety of modern calculus textbooks reveals that there are two very popular proofs of the divergence of the harmonic series. In this article, the authors survey these popular proofs along with many other proofs that are equally simple and…

  20. Practical Tools to Foster Harmonic Understanding

    ERIC Educational Resources Information Center

    Johnson, Erik

    2013-01-01

    Among the elements required to develop a comprehensive understanding of music is students' ability to perceive, recognize, and label the harmonies they hear. Harmonic dictation is among the strategies that teachers have traditionally chosen to help students develop harmonic awareness. However, the highly idiosyncratic ways that students approach…

  1. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  2. Constraining topology in harmonic space

    SciTech Connect

    Kunz, M.; Aghanim, N.; Forni, O.; Cayon, L.; Riazuelo, A.; Uzan, J. P.

    2006-01-15

    We consider several ways to test for topology directly in harmonic space by comparing the measured a{sub lm} with the expected correlation matrices. Two tests are of a frequentist nature while we compute the Bayesian evidence as the third test. Using correlation matrices for cubic and slab-space tori, we study how these tests behave as a function of the minimal scale probed and as a function of the size of the Universe. We also apply them to different first-year Wilkinson microwave anisotropy probe CMB maps and confirm that the Universe is compatible with being infinitely big for the cases considered. We argue that there is an information theoretical limit (given by the Kullback-Leibler divergence) on the size of the topologies that can be detected.

  3. Libsharp - spherical harmonic transforms revisited

    NASA Astrophysics Data System (ADS)

    Reinecke, M.; Seljebotn, D. S.

    2013-06-01

    We present libsharp, a code library for spherical harmonic transforms (SHTs), which evolved from the libpsht library and addresses several of its shortcomings, such as adding MPI support for distributed memory systems and SHTs of fields with arbitrary spin, but also supporting new developments in CPU instruction sets like the Advanced Vector Extensions (AVX) or fused multiply-accumulate (FMA) instructions. The library is implemented in portable C99 and provides an interface that can be easily accessed from other programming languages such as C++, Fortran, Python, etc. Generally, libsharp's performance is at least on par with that of its predecessor; however, significant improvements were made to the algorithms for scalar SHTs, which are roughly twice as fast when using the same CPU capabilities. The library is available at http://sourceforge.net/projects/libsharp/ under the terms of the GNU General Public License.

  4. Electron cyclotron harmonic wave acceleration

    NASA Technical Reports Server (NTRS)

    Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

    1987-01-01

    A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

  5. Electron cyclotron harmonic wave acceleration

    NASA Technical Reports Server (NTRS)

    Karimabadi, H.; Menyuk, C. R.; Sprangle, P.; Vlahos, L.

    1987-01-01

    A nonlinear analysis of particle acceleration in a finite bandwidth, obliquely propagating electromagnetic cyclotron wave is presented. It has been suggested by Sprangle and Vlahos in 1983 that the narrow bandwidth cyclotron radiation emitted by the unstable electron distribution inside a flaring solar loop can accelerate electrons outside the loop by the interaction of a monochromatic wave propagating along the ambient magnetic field with the ambient electrons. It is shown here that electrons gyrating and streaming along a uniform, static magnetic field can be accelerated by interacting with the fundamental or second harmonic of a monochromatic, obliquely propagating cyclotron wave. It is also shown that the acceleration is virtually unchanged when a wave with finite bandwidth is considered. This acceleration mechanism can explain the observed high-energy electrons in type III bursts.

  6. Quantum wormholes and harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Garay, Luis J.

    1993-01-01

    The quantum state of a wormhole can be represented by a path integral over all asymptotically Euclidean four-geometries and all matter fields which have prescribed values, the arguments of the wave function, on a three-surface which divides the space time manifold into two disconnected parts. Minisuperspace models which consist of a homogeneous massless scalar field coupled to a Friedmann-Robertson-Walker space time are considered. Once the path integral over the lapse function is performed, the requirement that the space time be asymptotically Euclidean can be accomplished by fixing the asymptotic gravitational momentum in the remaining path integral. It is argued that there does not exist any wave function which corresponds to asymptotic field configurations such that the effective gravitational constant is negative in the asymptotic region. Then, the wormhole wave functions can be written as linear combinations of harmonic oscillator wave functions.

  7. Harmonic analysis of perfusion pumps.

    PubMed

    Dougherty, F Carroll; Donovan, F M; Townsley, Mary I

    2003-12-01

    The controversy over the use of nonpulsatile versus pulsatile pumps for maintenance of normal organ function during ex vivo perfusion has continued for many years, but resolution has been limited by lack of a congruent mathematical definition of pulsatility. We hypothesized that the waveform frequency and amplitude, as well as the underlying mean distending pressure are all key parameters controlling vascular function. Using discrete Fourier Analysis, our data demonstrate the complexity of the pulmonary arterial pressure waveform in vivo and the failure of commonly available perfusion pumps to mimic in vivo dynamics. In addition, our data show that the key harmonic signatures are intrinsic to the perfusion pumps, are similar for flow and pressure waveforms, and are unchanged by characteristics of the downstream perfusion circuit or perfusate viscosity.

  8. High Orbital Angular Momentum Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Vieira, J.; Trines, R. M. G. M.; Alves, E. P.; Fonseca, R. A.; Mendonça, J. T.; Bingham, R.; Norreys, P.; Silva, L. O.

    2016-12-01

    We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.

  9. Harmonic generation with a dual frequency pulse.

    PubMed

    Keravnou, Christina P; Averkiou, Michalakis A

    2014-05-01

    Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

  10. High Orbital Angular Momentum Harmonic Generation.

    PubMed

    Vieira, J; Trines, R M G M; Alves, E P; Fonseca, R A; Mendonça, J T; Bingham, R; Norreys, P; Silva, L O

    2016-12-23

    We identify and explore a high orbital angular momentum (OAM) harmonics generation and amplification mechanism that manipulates the OAM independently of any other laser property, by preserving the initial laser wavelength, through stimulated Raman backscattering in a plasma. The high OAM harmonics spectra can extend at least up to the limiting value imposed by the paraxial approximation. We show with theory and particle-in-cell simulations that the orders of the OAM harmonics can be tuned according to a selection rule that depends on the initial OAM of the interacting waves. We illustrate the high OAM harmonics generation in a plasma using several examples including the generation of prime OAM harmonics. The process can also be realized in any nonlinear optical Kerr media supporting three-wave interactions.

  11. Coherence properties of high order harmonic radiation

    SciTech Connect

    Ditmire, T.; Budil, K.S.; Crane, J.K.; Nguyen, H.; Perry, M.D.; Salieres, P.; Huillier, A.L.

    1994-05-01

    The results of a series of experiments to characterize the coherence properties of xuv radiation produced by high-order harmonic generation in helium, neon and argon are reported and compared to predictions from an effective order model. The harmonics exhibit smooth, near gaussian spatial profiles, and have a divergence that is approximately constant ( < 12 mrad) in the plateau region and decreases ({approx}4 mrad) in the cutoff for f/17 focusing. For a bandwidth limited, 140 fsec incident pulse, we measure a harmonic line width of {Delta}{lambda}/{lambda} {approx} 2 {times} 10{sup {minus}3} at 30.3 nm. By reducing the spectral width of the driving pulse, harmonics with {Delta}{lambda}/{lambda} {approx} 2 {times} 10{sup {minus}4} can be produced. Absolute conversion efficiency as high as 10{sup {minus}7} for harmonic radiation as short as 20 nm has been achieved by using 400 fsec, 526 nm pulses from an Nd:Glass laser.

  12. Power Factor Correction to Mitigate Harmonic Distortion

    NASA Astrophysics Data System (ADS)

    Kochetkov, Gary

    Many direct current (DC) devices must receive their power from the alternating current (AC) grid. Rectifiers use diodes to create DC for these devices. Due to diodes' non-linear nature however, harmonics are created and these travel back into the grid. A significant presence of harmonics causes component heating and possible malfunction. A harmonic mitigation procedure is needed. With the correct usage of transistors, the current drawn by a rectifier can be manipulated to remove almost all harmonics. This process is called power factor correction (PFC), and formally acts to reduce the total harmonic distortion (THD) of the current. To investigate this, a three phase active rectifier was computer simulated and a controller was designed to provide switching signals for the transistors. Finally, the device was constructed in the laboratory to drive a DC motor, verifying its operating principle outside of the idealities of simulation.

  13. Harmonicity in slow protein dynamics

    NASA Astrophysics Data System (ADS)

    Hinsen, Konrad; Petrescu, Andrei-Jose; Dellerue, Serge; Bellissent-Funel, Marie-Claire; Kneller, Gerald R.

    2000-11-01

    The slow dynamics of proteins around its native folded state is usually described by diffusion in a strongly anharmonic potential. In this paper, we try to understand the form and origin of the anharmonicities, with the principal aim of gaining a better understanding of the principal motion types, but also in order to develop more efficient numerical methods for simulating neutron scattering spectra of large proteins. First, we decompose a molecular dynamics (MD) trajectory of 1.5 ns for a C-phycocyanin dimer surrounded by a layer of water into three contributions that we expect to be independent: the global motion of the residues, the rigid-body motion of the sidechains relative to the backbone, and the internal deformations of the sidechains. We show that they are indeed almost independent by verifying the factorization of the incoherent intermediate scattering function. Then, we show that the global residue motions, which include all large-scale backbone motions, can be reproduced by a simple harmonic model which contains two contributions: a short-time vibrational term, described by a standard normal mode calculation in a local minimum, and a long-time diffusive term, described by Brownian motion in an effective harmonic potential. The potential and the friction constants were fitted to the MD data. The major anharmonic contribution to the incoherent intermediate scattering function comes from the rigid-body diffusion of the sidechains. This model can be used to calculate scattering functions for large proteins and for long-time scales very efficiently, and thus provides a useful complement to MD simulations, which are best suited for detailed studies on smaller systems or for shorter time scales.

  14. Strong Enhancement of Second Harmonic Emission by Plasmonic Resonances at the Second Harmonic Wavelength.

    PubMed

    Metzger, Bernd; Gui, Lili; Fuchs, Jaco; Floess, Dominik; Hentschel, Mario; Giessen, Harald

    2015-06-10

    We perform second harmonic spectroscopy of aluminum nanoantenna arrays that exhibit plasmonic resonances at the second harmonic wavelength between 450 and 570 nm by focusing sub-30 fs laser pulses tunable from 900 to 1140 nm onto the nanoantenna arrays. We find that a plasmonic resonance at the second harmonic wavelength boosts the overall nonlinear process by more than an order of magnitude. In particular, in the measurement the resonant second harmonic polarization component is a factor of about 70 stronger when compared to the perpendicular off-resonant second harmonic polarization. Furthermore, the maximum of the second harmonic conversion efficiency is found to be slightly blue-shifted with respect to the peak of the linear optical far-field spectrum. This fact can be understood from a simple model that accounts for the almost off-resonant absorption at the fundamental wavelength and the resonant emission process at the second harmonic.

  15. High order harmonic generation in rare gases

    SciTech Connect

    Budil, Kimberly Susan

    1994-05-01

    The process of high order harmonic generation in atomic gases has shown great promise as a method of generating extremely short wavelength radiation, extending far into the extreme ultraviolet (XUV). The process is conceptually simple. A very intense laser pulse (I ~1013-1014 W/cm2) is focused into a dense (~1017 particles/cm3) atomic medium, causing the atoms to become polarized. These atomic dipoles are then coherently driven by the laser field and begin to radiate at odd harmonics of the laser field. This dissertation is a study of both the physical mechanism of harmonic generation as well as its development as a source of coherent XUV radiation. Recently, a semiclassical theory has been proposed which provides a simple, intuitive description of harmonic generation. In this picture the process is treated in two steps. The atom ionizes via tunneling after which its classical motion in the laser field is studied. Electron trajectories which return to the vicinity of the nucleus may recombine and emit a harmonic photon, while those which do not return will ionize. An experiment was performed to test the validity of this model wherein the trajectory of the electron as it orbits the nucleus or ion core is perturbed by driving the process with elliptically, rather than linearly, polarized laser radiation. The semiclassical theory predicts a rapid turn-off of harmonic production as the ellipticity of the driving field is increased. This decrease in harmonic production is observed experimentally and a simple quantum mechanical theory is used to model the data. The second major focus of this work was on development of the harmonic "source". A series of experiments were performed examining the spatial profiles of the harmonics. The quality of the spatial profile is crucial if the harmonics are to be used as the source for experiments, particularly if they must be refocused.

  16. The Effect of Cochlear Damage on the Sensitivity to Harmonicity.

    PubMed

    Bonnard, Damien; Dauman, René; Semal, Catherine; Demany, Laurent

    A sum of simultaneous pure tones with harmonic relationships (i.e., simple frequency ratios) is normally heard as a single sound, with a single pitch, even when its components are fully resolved in the auditory periphery. This perceptual phenomenon called "harmonic fusion" is thought to play an important role in auditory scene analysis as listeners often have to segregate simultaneous harmonic sounds with different fundamental frequencies. The present study explored the consequences of mild or moderate cochlear hearing loss for the sensitivity to harmonicity and the detection of inharmonicity. The subjects were 12 normal-hearing (NH) listeners and 8 listeners with cochlear hearing loss amounting to 30 to 50 dB (mean: 42 dB) from 0.25 to 3 kHz. In each subject, thresholds for the detection of a change in the frequency ratio of simultaneous pure tones were measured with an adaptive forced-choice procedure. The standard frequency ratio was either harmonic (2:1, i.e., one octave) or inharmonic (0.8 or 1.2 octaves). The tones were presented at a low sensation level (at most 15 dB) within broadband noise, to minimize their cochlear interactions. In the main experimental conditions, the frequency register of the stimuli varied randomly within each trial, so that subjects were forced to process frequency ratios to achieve good performance; frequency discrimination was not sufficient. In other conditions, by contrast, frequency discrimination was sufficient to perform the task optimally. For both groups of subjects, thresholds in the main experimental conditions were lower (i.e., better) when the standard frequency ratio was harmonic than when it was inharmonic. This effect, revealing sensitivity to harmonicity, was weak for some members of the hearing-impaired group, but could be observed even in subjects showing a very poor frequency discrimination ability. The two groups, however, differed from each other with respect to the detection of inharmonicity: for the NH group

  17. Intravascular ultrasound tissue harmonic imaging in vivo.

    PubMed

    Frijlink, Martijn E; Goertz, David E; van Damme, Luc C A; Krams, Rob; van der Steen, Antonius F W

    2006-10-01

    Tissue harmonic imaging (THI) has been shown to increase image quality of medical ultrasound in the frequency range from 2 to 10 MHz and might, therefore, also be used to improve image quality in intravascular ultrasound (IVUS). In this study we constructed a prototype IVUS system that could operate in both fundamental frequency and second harmonic imaging modes. This system uses a conventional, continuously rotating, single-element IVUS catheter and was operated in fundamental 20 MHz, fundamental 40 MHz, and harmonic 40 MHz modes (transmit 20 MHz, receive 40 MHz). Hydrophone beam characterization measurements demonstrated the build-up of a second harmonic signal as a function of increasing pressure. Imaging experiments were conducted in both a tissue-mimicking phantom and in an atherosclerotic animal model in vivo. Acquisitions of fundamental 20 and 40 MHz and second harmonic acquisitions resulted in cross sections of the phantom and a rabbit aorta. The harmonic results of the imaging experiments showed the feasibility of intravascular THI with a conventional IVUS catheter both in a phantom and in vivo. The harmonic acquisitions also showed the potential of THI to reduce image artifacts compared to fundamental imaging.

  18. Clinical use of ultrasound tissue harmonic imaging.

    PubMed

    Tranquart, F; Grenier, N; Eder, V; Pourcelot, L

    1999-07-01

    The recent introduction of tissue harmonic imaging could resolve the problems related to ultrasound in technically difficult patients by providing a marked improvement in image quality. Tissue harmonics are generated during the transmit phase of the pulse-echo cycle, that is, while the transmitted pulse propagates through tissue. Tissue harmonic images are formed by utilizing the harmonic signals that are generated by tissue and by filtering out the fundamental echo signals that are generated by the transmitted acoustic energy. To achieve this, two processes could be used; one by using filters for fundamental and harmonic imaging and the second using two simultaneous pulses with a 180 degrees difference in phase. The introduction of harmonics allows increased penetration without a loss of detail, by obtaining a clearer image at depth with significantly less compromise to the image quality caused by the use of lower frequencies. This imaging mode could be used in different organs with a heightening of low-contrast lesions through artefact reduction, as well as by the induced greater intrinsic contrast sensitivity of the harmonic imaging mode.

  19. Harmonization in laboratory medicine: the complete picture.

    PubMed

    Plebani, Mario

    2013-04-01

    Evidence of the acute lack of interchangeable laboratory results and consensus in current practice among clinical laboratories has underpinned greater attention to standardization and harmonization projects. Although the focus is mainly on the standardization of measurement procedures, the scope of harmonization goes beyond method and analytical results: it includes all other aspects of laboratory testing, including terminology and units, report formats, reference intervals and decision limits, as well as test profiles and criteria for the interpretation of results. This review provides further insight on the issue of harmonization in laboratory medicine in view of the urgent need for a complete picture now that old and new drivers are calling for more effective efforts in this field. The main drivers for standardization and harmonization projects are first and foremost patient safety, but also the increasing trends towards consolidation and networking of clinical laboratories, accreditation programs, clinical governance, and advances in Information Technology (IT), including the electronic patient record. The harmonization process, which should be considered a three-tier approach involving local, national and international fronts, must go beyond the harmonization of methods and analytical results to include all other aspects of laboratory testing. A pertinent example of the importance of a complete picture in harmonization programs is given by the National Bone Health Alliance working in the field of bone turnover markers in cooperation with scientific societies including the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC).

  20. Near BPS skyrmions and restricted harmonic maps

    NASA Astrophysics Data System (ADS)

    Speight, J. M.

    2015-06-01

    Motivated by a class of near BPS Skyrme models introduced by Adam, Sánchez-Guillén and Wereszczyński, the following variant of the harmonic map problem is introduced: a map φ :(M, g) →(N, h) between Riemannian manifolds is restricted harmonic if it locally extremizes E2 on its SDiff(M) orbit, where SDiff(M) denotes the group of volume preserving diffeomorphisms of (M, g), and E2 denotes the Dirichlet energy. It is conjectured that near BPS skyrmions tend to restricted harmonic maps in the BPS limit. It is shown that φ is restricted harmonic if and only if φ∗ h has exact divergence, and a linear stability theory of restricted harmonic maps is developed, from which it follows that all weakly conformal maps are stable restricted harmonic. Examples of restricted harmonic maps in every degree class R3 → SU(2) and R2 →S2 are constructed. It is shown that the axially symmetric BPS skyrmions on which all previous analytic studies of near BPS Skyrme models have been based, are not restricted harmonic, casting doubt on the phenomenological predictions of such studies. The problem of minimizing E2 for φ :Rk → N over all linear volume preserving diffeomorphisms is solved explicitly, and a deformed axially symmetric family of Skyrme fields constructed which are candidates for approximate near BPS skyrmions at low baryon number. The notion of restricted harmonicity is generalized to restricted F-criticality where F is any functional on maps (M, g) →(N, h) which is, in a precise sense, geometrically natural. The case where F is a linear combination of E2 and E4, the usual Skyrme term, is studied in detail, and it is shown that inverse stereographic projection R3 →S3 ≡ SU(2) is stable restricted F-critical for every such F.

  1. Instanton solutions on the polymer harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Austrich-Olivares, Joan A.; Garcia-Chung, Angel; Vergara, J. David

    2017-06-01

    We have computed, using instanton methods, the first allowed energy band for the polymer harmonic oscillator. The eigenvalues within the band are labelled by a discrete parameter λ which results from the non-separability of the polymer Hilbert space. It is shown throughout the article the role played by λ in the full quantization of the polymer harmonic oscillator. The result is consistent with the band structure of the standard quantum pendulum but with pure point spectrum. Consequently, an effective infinite degeneracy emerges in the formal limit μ/l0 \\to 0 where l 0 is the characteristic length of the vacuum eigenfunction of a quantum harmonic oscillator.

  2. Asymptotic porosity of planar harmonic measure

    NASA Astrophysics Data System (ADS)

    Graczyk, Jacek; Świaţek, Grzegorz

    2013-04-01

    We study the distribution of harmonic measure on connected Julia sets of unicritical polynomials. Harmonic measure on a full compact set in ℂ is always concentrated on a set which is porous for a positive density of scales. We prove that there is a topologically generic set {A} in the boundary of the Mandelbrot set such that for every cin {A}, β>0, and λ∈(0,1), the corresponding Julia set is a full compact set with harmonic measure concentrated on a set which is not β-porous in scale λ n for n from a set with positive density amongst natural numbers.

  3. Harmonic Analysis on Quantum Tori

    NASA Astrophysics Data System (ADS)

    Chen, Zeqian; Xu, Quanhua; Yin, Zhi

    2013-09-01

    This paper is devoted to the study of harmonic analysis on quantum tori. We consider several summation methods on these tori, including the square Fejér means, square and circular Poisson means, and Bochner-Riesz means. We first establish the maximal inequalities for these means, then obtain the corresponding pointwise convergence theorems. In particular, we prove the noncommutative analogue of the classical Stein theorem on Bochner-Riesz means. The second part of the paper deals with Fourier multipliers on quantum tori. We prove that the completely bounded L p Fourier multipliers on a quantum torus are exactly those on the classical torus of the same dimension. Finally, we present the Littlewood-Paley theory associated with the circular Poisson semigroup on quantum tori. We show that the Hardy spaces in this setting possess the usual properties of Hardy spaces, as one can expect. These include the quantum torus analogue of Fefferman's H1-BMO duality theorem and interpolation theorems. Our analysis is based on the recent developments of noncommutative martingale/ergodic inequalities and Littlewood-Paley-Stein theory.

  4. A randomized clinical trial comparing long-term clopidogrel vs aspirin monotherapy beyond dual antiplatelet therapy after drug-eluting coronary stent implantation: Design and rationale of the Harmonizing Optimal Strategy for Treatment of coronary artery stenosis-Extended Antiplatelet Monotherapy (HOST-EXAM) trial.

    PubMed

    Lee, Heesun; Koo, Bon-Kwon; Park, Kyung Woo; Shin, Eun-Seok; Lim, Sang Wook; Rha, Seung-Woon; Bae, Jang-Whan; Jeon, Dong Woon; Oh, Seok-Kyu; Hur, Seung-Ho; Kim, Bum-Su; Lee, Jung-Hee; Park, Tae-Ho; Lee, Nam Ho; Kim, Hyo-Soo

    2017-03-01

    Percutaneous coronary intervention (PCI) has been developed by drug-eluting stent (DES), but stent implantation has brought the issue of stent thrombosis and optimal antiplatelet therapy. Guidelines recommend at least 6- to 12 months of dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 receptor inhibitor such as clopidogrel. Beyond DAPT after PCI with DES, however, there has been still a debate for antiplatelet regimen. Therefore, we report on the upcoming HOST-EXAM trial (NCT02044250), which will evaluate the efficacy and safety of aspirin and clopidogrel monotherapies beyond DAPT after DES implantation. The HOST-EXAM is a prospective, randomized, open-label, multicenter, comparative effectiveness trial, to compare between clopidogrel (75 mg once daily) and aspirin (100 mg once daily) as long-term antiplatelet agents. A total of 5,530 patients with no clinical events during combined antiplatelet therapy for 12±6 months after index PCI will be screened, enrolled, and randomized to either group (1:1 ratio) receiving antiplatelet monotherapy for 2 years. The primary endpoint will be the rate of clinical events defined as a composite of all-cause death, nonfatal myocardial infarction, stroke, readmission due to acute coronary syndrome, or major bleeding at 24 months after randomization. The HOST-EXAM will be the first large-scale randomized controlled study to directly compare the efficacy and safety of long-term antiplatelet monotherapy beyond DAPT after DES implantation. This study will provide clinical evidence to establish optimal regimen for long-term antiplatelet therapy after DES implantation. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. The International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR) - A Pathway for Harmonization.

    PubMed

    Myers, Gary L; Miller, W Greg

    2016-02-01

    Results from clinical laboratory measurement procedures must be equivalent to enable effective use of clinical guidelines for disease diagnosis and patient management. Analytical results that are harmonized and independent of the measurement system, time, and location of testing is essential for providing adequate patient care. The key to generating harmonized results is establishing traceability to an accepted reference standard where available. Awareness of the benefits of having traceable measurement results that are harmonized has increased along with efforts to develop approaches to enable and facilitate the implementation of harmonization. Although several organizations are addressing harmonization of test procedures, centralized and cooperative global oversight is needed to ensure that the most important tests are being addressed and resources are optimally used. Working with its domestic and international partners, the American Association for Clinical Chemistry (AACC) has created an International Consortium for Harmonization of Clinical Laboratory Results. Advances in this area will improve the quality of patient care.

  6. Geomagnetic local and regional harmonic analyses.

    USGS Publications Warehouse

    Alldredge, L.R.

    1982-01-01

    Procedures are developed for using rectangular and cylindrical harmonic analyses in local and regional areas. Both the linear least squares analysis, applicable when component data are available, and the nonlinear least squares analysis, applicable when only total field data are available, are treated. When component data are available, it is advantageous to work with residual fields obtained by subtracting components derived from a harmonic potential from the observed components. When only total field intensity data are available, they must be used directly. Residual values cannot be used. Cylindrical harmonic analyses are indicated when fields tend toward cylindrical symmetry; otherwise, rectangular harmonic analyses will be more advantageous. Examples illustrating each type of analysis are given.-Author

  7. SEVENTH HARMONIC 20 GHz CO-GENERATOR

    SciTech Connect

    Hirshfield, Jay L

    2014-04-08

    To satisfy the need for multi-MW rf sources in frequency ranges where commercial sources do not exist, a study was undertaken on a class of devices based on gyro-harmonic frequency multiplication. This mechanism relies upon adding energy in gyrating motion to a linear electron beam that traverses a rotating-mode TE111-mode drive cavity in a dc magnetic field. The beam then drifts along the magnetic field into a second cavity, operating in the TEn11-mode tuned to the nth harmonic of the drive cavity. Studies of this configuration have been carried out for 2 < n < 7. Results are given for multi-MW, efficient operation of a 7th harmonic device operating at 20 GHz, and a 2nd harmonic device operating at 22.4 GHz.

  8. Tracking Comb Filter Suppresses Welder Harmonics

    NASA Technical Reports Server (NTRS)

    Delcher, Ray C.

    1992-01-01

    Tracking comb filter includes charge-coupled-device delay line and phase-locked loop. Filter removes harmonics of frequency of repetition of welding-current pulses from acoustic-emission signal. Spurious signals reduced almost to fundamental limit.

  9. Perturbative High Harmonic Wave Front Control

    NASA Astrophysics Data System (ADS)

    Li, Zhengyan; Brown, Graham; Ko, Dong Hyuk; Kong, Fanqi; Arissian, Ladan; Corkum, P. B.

    2017-01-01

    We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method. We will show that it is possible to enhance the peak intensity by orders of magnitude without a physical optical element in the path of the extreme ultraviolet (XUV) beam. Through perturbative wave-front control, XUV beams can be created with a flexibility approaching what technology allows for visible and infrared light.

  10. New ladder operators for the monopole harmonics

    SciTech Connect

    Fakhri, H.; Dehghani, A.; Jafari, A.

    2007-02-15

    Using the ladder operators shifting the index m of the associated Jacobi functions, for a given n, the monopole harmonics and their corresponding angular momentum operators are, respectively, extracted as the irreducible representation space and generators of su(2) Lie algebra. The indices n and m play the role of principal and azimuthal quantum numbers. By introducing the ladder operators shifting the index n of the same associated Jacobi functions, we also get a new type of the raising and lowering relations which are realized by the operators shifting only the index n of the monopole harmonics. Moreover, other symmetries, including the transformation of the irreducible representation spaces into each other, are derived based on the operators that shift the indices n and m of the monopole harmonics simultaneously and agreeably as well as simultaneously and inversely. Our results are reduced to spherical harmonics by eliminating magnetic charge of the monopole.

  11. Tracking Comb Filter Suppresses Welder Harmonics

    NASA Technical Reports Server (NTRS)

    Delcher, Ray C.

    1992-01-01

    Tracking comb filter includes charge-coupled-device delay line and phase-locked loop. Filter removes harmonics of frequency of repetition of welding-current pulses from acoustic-emission signal. Spurious signals reduced almost to fundamental limit.

  12. Improved Efficiency Type II Second Harmonic Generation

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J., Jr.

    2009-01-01

    Second harmonic efficiency is limited by lateral and temporal separation of the ordinary and extraordinary components of the fundamental. A mode locked dual beam laser demonstrated these effects and a novel method to minimize them.

  13. Terahertz optics: Terahertz-driven harmonics

    NASA Astrophysics Data System (ADS)

    Kim, K. Y.; You, Y. S.

    2014-02-01

    Researchers have demonstrated high-harmonic generation using strong terahertz pulses in a bulk solid without damaging it. The mechanism underpinning such an extreme nonlinearity also generates coherent electromagnetic radiation covering the terahertz, infrared and optical regions.

  14. Dispersion-enhanced third-harmonic microscopy

    NASA Astrophysics Data System (ADS)

    Stock, Christian; Zlatanov, Kaloyan; Halfmann, Thomas

    2017-06-01

    We demonstrate strong enhancements of signal yield and image contrast in third-harmonic microscopy by appropriate choice of driving laser wavelength to modulate the phase-matching conditions of the conversion process by dispersion control. Tuning the laser wavelength in the range of 1010 - 1350 nm at samples containing interfaces with water and glass, we obtained large signal enhancements up to a factor of 19, and improvements in the image contrast by an order of magnitude. The effect is most pronounced at interfaces with media of small and/or not too different nonlinear optical susceptibilities, e.g., as it is the case in typical samples in harmonic microscopy. Beyond the demonstration of this new variant of third-harmonic microscopy, our findings are also of relevance to a proper choice of laser systems for harmonic microscopy setups.

  15. The Case of the Missing Harmonic Structure

    SciTech Connect

    Arp, U.

    2007-01-19

    Classical synchrotron radiation theory predicts emission in harmonics of the revolution frequency of the radiating particles. The Synchrotron Ultraviolet Radiation Facility SURF is an electron storage ring based on the weak focusing principle. The particles travel on a near perfect circular path, which makes SURF an ideal test-bed for synchrotron radiation theory. The harmonic structure of the radiation emitted by the electrons stored in SURF will be explored.

  16. Harmonic distortion in microwave photonic filters.

    PubMed

    Rius, Manuel; Mora, José; Bolea, Mario; Capmany, José

    2012-04-09

    We present a theoretical and experimental analysis of nonlinear microwave photonic filters. Far from the conventional condition of low modulation index commonly used to neglect high-order terms, we have analyzed the harmonic distortion involved in microwave photonic structures with periodic and non-periodic frequency responses. We show that it is possible to design microwave photonic filters with reduced harmonic distortion and high linearity even under large signal operation.

  17. Power Divider for Harmonically Rich Waveforms

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III (Inventor)

    2001-01-01

    A power divider divides an RF signal into two output signals having a phase difference of 180 deg. or a multiple thereof. When the RF signal is a square wave or another harmonically rich signal. the phases of the fundamental and the harmonics have the proper relationship. The divider can be implemented in the form of microstrips on a board, with one of the output microstrips having several bends to provide a different electrical length from the other.

  18. Prediction of Metastasis Using Second Harmonic Generation

    DTIC Science & Technology

    2016-07-01

    photon focal volume and the thin tissue section), producing a single F and B image for each sample. Then an arbitrary threshold was chosen by a blinded...AWARD NUMBER: W81XWH-15-1-0040 TITLE: Prediction of Metastasis Using Second Harmonic Generation PRINCIPAL INVESTIGATOR: Edward Brown...ABOVE ADDRESS. 1. REPORT DATE July 2016 2. REPORT TYPE Final 3. DATES COVERED 1May2015 - 30Apr2016 Prediction of Metastasis Using Second Harmonic

  19. Flight Operations for Higher Harmonic Control Research

    DTIC Science & Technology

    1991-03-01

    Harmonic Control System," Journal of the American Helicopter Society, January 1985. 7. McKeown, J.C., "Helicopter Design Requirements ," Lecture notes...0 NAVAL POSTGRADUATE SCHOOL Monterey, California AD-A242 478 ,j’ STATS4 G’CtAD’%3P’ THESIS FLIGHT OPERATIONS FOR HIGHER HARMONIC CONTROL RESEARCH by...SECURITY CLASSIFICATION OF THIS PAGE Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 la REPORT SECURITY CLASSIFICATION Ib RESTRICTIVE

  20. Time-Variant Least Squares Harmonic Modeling

    DTIC Science & Technology

    2003-01-01

    SNR situations. We show applicability to high accuracy speech pitch and heart sound beat epoch estimation. 1. INTRODUCTION Harmonic modeling...techniques have been successfully used for low bit-rate speech coding; however their performance degrades at low SNR . The LSH model is capable of...producing more accurate and robust harmonic analysis, even at very low SNR ; however, as will be shown, its performance degrades significantly with rapid

  1. Coherent states for the nonlinear harmonic oscillator

    SciTech Connect

    Ghosh, Subir

    2012-06-15

    Wave packets for the quantum nonlinear oscillator are considered in the generalized coherent state framework. To first order in the nonlinearity parameter the coherent state behaves very similar to its classical counterpart. The position expectation value oscillates in a simple harmonic manner. The energy-momentum uncertainty relation is time independent as in a harmonic oscillator. Various features (such as the squeezed state nature) of the coherent state have been discussed.

  2. Making A Circular-Harmonic Filter

    NASA Technical Reports Server (NTRS)

    Cheng, Yeou Yen

    1989-01-01

    Optical image-correlating system made rotationally invariant. Experiment shows circular-harmonic filter generated optically. Hologram made by phase-shifted-double-exposure procedure. Filter used in optical image-recognition system based on correlation between target (image to be recognized) and matched spatial filter. In addition to usual invariance under translation of target, circular harmonic filter invariant under rotation of target; peak intensity of illumination at origin of correlation plane does not vary when target rotated about optical axis.

  3. Object recognition using cylindrical harmonic filter.

    PubMed

    Guerrero Bermúdez, Jáder

    2004-06-28

    We present the cylindrical harmonic filter for three-dimensional (3D) discrete correlation between range data. The filter guarantees invariance of the correlation peak intensity under target rotation around z-axis. It can be considered a harmonic decomposition, in cylindrical coordinates, of the 3D Fourier spectrum of the target. Some simulation results confirm the in-plane rotation invariance and the discrimination of the filter.

  4. HARMONIC CAVITY PERFORMANCE FOR NSLS-II

    SciTech Connect

    BLEDNYKH, A.; KRINSKY, S.; PODOBEDOV, B.; ROSE, J.; TOWNE, N.; WANG, J.M.

    2005-05-15

    NSLS-II is a 3 GeV ultra-high brightness storage ring planned to succeed the present NSLS rings at BNL. Ultralow emittance combined with short bunch length means that it is critical to minimize the effects of Touschek scattering and coherent instabilities. Improved lifetime and stability can be achieved by including a third-harmonic RF cavity in the baseline design. This paper describes the required harmonic RF parameters and the expected system performance.

  5. Quantum harmonic oscillator with superoscillating initial datum

    SciTech Connect

    Buniy, R. V.; Struppa, D. C.; Colombo, F.; Sabadini, I.

    2014-11-15

    In this paper, we study the evolution of superoscillating initial data for the quantum driven harmonic oscillator. Our main result shows that superoscillations are amplified by the harmonic potential and that the analytic solution develops a singularity in finite time. We also show that for a large class of solutions of the Schrödinger equation, superoscillating behavior at any given time implies superoscillating behavior at any other time.

  6. Measuring Spherical Harmonic Coefficients on a Sphere

    SciTech Connect

    Pollaine, S; Haan, S W

    2003-05-16

    The eigenfunctions of Rayleigh-Taylor modes on a spherical capsule are the spherical harmonics Y{sub l,m} These can be measured by measuring the surface perturbations along great circles and fitting them to the first few modes by a procedure described in this article. For higher mode numbers, it is more convenient to average the Fourier power spectra along the great circles, and then transform them to spherical harmonic modes by an algorithm derived here.

  7. Higher-Order Harmonic Generation from Fullerene by Means of the Plasma Harmonic Method

    SciTech Connect

    Ganeev, R. A.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ozaki, T.; Wong, M. C. H.; Brichta, J. P.; Bhardwaj, V. R.

    2009-01-09

    We demonstrate, for the first time, high-order harmonic generation from C{sub 60} by an intense femtosecond Ti:sapphire laser. Laser-produced plasmas from C{sub 60}-rich epoxy and C{sub 60} films were used as the nonlinear media. Harmonics up to the 19th order were observed. The harmonic yield from fullerene-rich plasma is about 25 times larger compared with those produced from a bulk carbon target. Structural studies of plasma debris confirm the presence and integrity of fullerenes within the plasma plume, indicating fullerenes as the source of high-order harmonics.

  8. Limitations in Using Multiple Imputation to Harmonize Individual Participant Data for Meta-Analysis.

    PubMed

    Siddique, Juned; de Chavez, Peter J; Howe, George; Cruden, Gracelyn; Brown, C Hendricks

    2017-02-27

    Individual participant data (IPD) meta-analysis is a meta-analysis in which the individual-level data for each study are obtained and used for synthesis. A common challenge in IPD meta-analysis is when variables of interest are measured differently in different studies. The term harmonization has been coined to describe the procedure of placing variables on the same scale in order to permit pooling of data from a large number of studies. Using data from an IPD meta-analysis of 19 adolescent depression trials, we describe a multiple imputation approach for harmonizing 10 depression measures across the 19 trials by treating those depression measures that were not used in a study as missing data. We then apply diagnostics to address the fit of our imputation model. Even after reducing the scale of our application, we were still unable to produce accurate imputations of the missing values. We describe those features of the data that made it difficult to harmonize the depression measures and provide some guidelines for using multiple imputation for harmonization in IPD meta-analysis.

  9. Harmonic Oscillators as Bridges between Theories

    NASA Astrophysics Data System (ADS)

    Kim, Y. S.; Noz, Marilyn E.

    2005-03-01

    Other than scattering problems where perturbation theory is applicable, there are basically two ways to solve problems in physics. One is to reduce the problem to harmonic oscillators, and the other is to formulate the problem in terms of two-by-two matrices. If two oscillators are coupled, the problem combines both two-by-two matrices and harmonic oscillators. This method then becomes a powerful research tool to cover many different branches of physics. Indeed, the concept and methodology in one branch of physics can be translated into another through the common mathematical formalism. It is noted that the present form of quantum mechanics is largely a physics of harmonic oscillators. Special relativity is the physics of the Lorentz group which can be represented by the group of by two-by-two matrices commonly called SL(2, c). Thus the coupled harmonic oscillators can therefore play the role of combining quantum mechanics with special relativity. Both Paul A. M. Dirac and Richard P. Feynman were fond of harmonic oscillators, while they used different approaches to physical problems. Both were also keenly interested in making quantum mechanics compatible with special relativity. It is shown that the coupled harmonic oscillators can bridge these two different approaches to physics.

  10. High order harmonics from relativistic electron spikes

    NASA Astrophysics Data System (ADS)

    Pirozhkov, Alexander S.; Kando, Masaki; Esirkepov, Timur Zh; Gallegos, Pablo; Ahmed, Hamad; Ragozin, Eugene N.; Faenov, Anatoly Ya; Pikuz, Tatiana A.; Kawachi, Tetsuya; Sagisaka, Akito; Koga, James K.; Coury, Mireille; Green, James; Foster, Peta; Brenner, Ceri; Dromey, Brendan; Symes, Dan R.; Mori, Michiaki; Kawase, Keigo; Kameshima, Takashi; Fukuda, Yuji; Chen, Liming; Daito, Izuru; Ogura, Koichi; Hayashi, Yukio; Kotaki, Hideyuki; Kiriyama, Hiromitsu; Okada, Hajime; Nishimori, Nobuyuki; Imazono, Takashi; Kondo, Kiminori; Kimura, Toyoaki; Tajima, Toshiki; Daido, Hiroyuki; Rajeev, Pattathil; McKenna, Paul; Borghesi, Marco; Neely, David; Kato, Yoshiaki; Bulanov, Sergei V.

    2014-09-01

    A new regime of relativistic high-order harmonic generation has been discovered (Pirozhkov 2012 Phys. Rev. Lett. 108 135004). Multi-terawatt relativistic-irradiance (>1018 W cm-2) femtosecond (˜30-50 fs) lasers focused to underdense (few × 1019 cm-3) plasma formed in gas jet targets produce comb-like spectra with hundreds of even and odd harmonic orders reaching the photon energy of 360 eV, including the ‘water window’ spectral range. Harmonics are generated either by linearly or circularly polarized pulses from the J-KAREN (KPSI, JAEA) and Astra Gemini (CLF, RAL, UK) lasers. The photon number scalability has been demonstrated with a 120 TW laser, producing 40 μJ sr-1 per harmonic at 120 eV. The experimental results are explained using particle-in-cell simulations and catastrophe theory. A new mechanism of harmonic generation by sharp, structurally stable, oscillating electron spikes at the joint of the boundaries of the wake and bow waves excited by a laser pulse is introduced. In this paper, detailed descriptions of the experiments, simulations and model are provided and new features are shown, including data obtained with a two-channel spectrograph, harmonic generation by circularly polarized laser pulses and angular distribution.

  11. Linking high harmonics from gases and solids

    NASA Astrophysics Data System (ADS)

    Vampa, G.; Hammond, T. J.; Thiré, N.; Schmidt, B. E.; Légaré, F.; McDonald, C. R.; Brabec, T.; Corkum, P. B.

    2015-06-01

    When intense light interacts with an atomic gas, recollision between an ionizing electron and its parent ion creates high-order harmonics of the fundamental laser frequency. This sub-cycle effect generates coherent soft X-rays and attosecond pulses, and provides a means to image molecular orbitals. Recently, high harmonics have been generated from bulk crystals, but what mechanism dominates the emission remains uncertain. To resolve this issue, we adapt measurement methods from gas-phase research to solid zinc oxide driven by mid-infrared laser fields of 0.25 volts per ångström. We find that when we alter the generation process with a second-harmonic beam, the modified harmonic spectrum bears the signature of a generalized recollision between an electron and its associated hole. In addition, we find that solid-state high harmonics are perturbed by fields so weak that they are present in conventional electronic circuits, thus opening a route to integrate electronics with attosecond and high-harmonic technology. Future experiments will permit the band structure of a solid to be tomographically reconstructed.

  12. Absorption of harmonic light in plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Vincenti, Maria A.; de Ceglia, Domenico; Scalora, Michael

    2016-09-01

    Surface plasmons are known for their ability to provide large field enhancement at the interface between a metal and another medium. They can be observed in a variety of structures ranging from plain metallic films to nanoparticles and gratings. Thanks to their large electric field enhancement, surface plasmons have also been exploited for the enhancement of second and third harmonic generation. In fact, metals possess a relatively high third order susceptibility and, although dipole-allowed quadratic nonlinearities are not present in the bulk, they also display an effective second order response that arises from symmetry breaking at the surface, magnetic dipoles (Lorentz force), inner-core electrons, convective nonlinear sources, and electron gas pressure. While much attention has been devoted to achieve efficient excitation of surface plasmons to improve far-field harmonic generation, little or no attention has been paid to the dissipation of the generated harmonic light. Therefore, we undertake a discussion of both harmonic generation and absorption in simple metallic/dielectric interfaces with or without excitation of surface plasmons. We demonstrate that, despite the best efforts embarked upon to study plasmon excitation, the absorbed harmonic energy can far surpass the energy emitted in the far-field. These findings suggest that quantification of the absorbed harmonic light should be an important parameter in evaluating designs of plasmonic nanostructures for frequency mixing.

  13. Spherical Harmonic Analysis via Bayesian Inference

    NASA Astrophysics Data System (ADS)

    Muir, J. B.; Tkalcic, H.

    2014-12-01

    The real spherical harmonics form a compact, simple and commonly used set of basis functions for describing fields in tomographic inverse problems. It is therefore often useful to perform spherical harmonic analysis on data to represent it in the spherical harmonic parametrisation. Most existing algorithms, based on Fourier transforms, require that data be interpolated to a regular grid; this is not appropriate for the sparse, irregularly distributed data found in many geophysical applications. Instead, this work casts the problem of spherical harmonic analysis as an inverse problem, and applies the methods of Bayesian inference to overcome regularization problems in the inversion. This allows irregular data to be easily handled, and directly provides error estimates for the inverted spherical harmonic parameters. Synthetic tests have shown that this method easily handles relatively large amounts of added Gaussian noise. So far, this method has been applied to estimate the power in each harmonic degree for tomographic maps of the deep mantle based on PKP-PKIKP and PcP-P differential travel times, showing that they agree at global length scales despite local heterogeneity results being heavily influenced by data coverage. This potentially allows for simple heuristic arguments to constrain the global variation in core-mantle boundary topography based on the similarity between PKP and PcP derived tomographic maps.

  14. Harmonic moment dynamics in Laplacian growth.

    PubMed

    Leshchiner, Alexander; Thrasher, Matthew; Mineev-Weinstein, Mark B; Swinney, Harry L

    2010-01-01

    Harmonic moments are integrals of integer powers of z=x+iy over a domain. Here, the domain is an exterior of a bubble of air growing in an oil layer between two horizontal closely spaced plates. Harmonic moments are a natural basis for such Laplacian growth phenomena because, unlike other representations, these moments linearize the zero surface tension problem [S. Richardson, J. Fluid Mech. 56, 609 (1972)], so that all moments except the lowest one (the area of the bubble) are conserved in time. In our experiments, we directly determine the harmonic moments and show that for nonzero surface tension, all moments (except the lowest one) decay in time rather than exhibiting the divergences of other representations. Further, we derive an expression that relates the derivative of the k(th) harmonic moment M(k) to measurable quantities (surface tension, viscosity, the distance between the plates, and a line integral over the contour encompassing the growing bubble). The laboratory observations are in good accord with the expression we derive for dM(k)/dt , which is proportional to the surface tension; thus in the zero surface tension limit, the moments (above k=0) are all conserved, in accord with Richardson's theory. In addition, from the measurements of the time evolution of the harmonic moments we obtain a value for the surface tension that is within 20% of the accepted value. In conclusion, our analysis and laboratory observations demonstrate that an interface dynamics description in terms of harmonic moments is physically realizable and robust.

  15. Stability and harmonics in thyristor controlled reactors

    SciTech Connect

    Bohmann, L.J.; Lasseter, R.H. )

    1990-04-01

    Harmonics that arise from the interaction of thyristor controlled reactors (TCRs) and power systems can sometimes cause stability problems that are difficult to analyze since the harmonics are affected by the power system. The classical method for calculating harmonics is to calculate the harmonic current assuming an infinite bus at the high side of the TCR transformer. This current is then used as a harmonic current source on the ac system. The basic problem with this method is that many of the interactions between the ac system and the TCR are neglected. In this paper two methods for studying the neglected interactions are described. The first uses state variables to analyze the circuit containing the TCR. The resulting equations are linear differential equations with periodic coefficients. This formulation allows the study of stability, periodic operation, and resonance which can not be achieved by other methods. The second method uses a fourier matrix description of the TCR. In this model the coupling between the different harmonics due to the switching is clearly shown.

  16. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, Walter F.

    1985-01-01

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  17. Dual aperture dipole magnet with second harmonic component

    DOEpatents

    Praeg, W.F.

    1983-08-31

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  18. Second harmonic generation in collagen

    NASA Astrophysics Data System (ADS)

    Reiser, Karen M.; Stoller, Patrick; Celliers, Peter; Rubenchik, Alexander; Bratton, Clay; Yankelevich, Diego

    2003-11-01

    Collagen possesses a strong second order nonlinear susceptibility; when it is irradiated with intense laser light, some of the reflected and transmitted light will have twice the frequency of the incident beam, a phenomenon known as second harmonic generation (SHG). Polarization modulation of an ultra-short pulse laser beam can be used to simultaneously measure collagen fiber orientation, SHG intensity, and a parameter related to the second order non-linear susceptibility. This technique has made it possible to discriminate among patterns of fibrillar orientation in many tissues. In the present study the role that organizational complexity plays in the relationship between nonlinear optical properties and collagen structure is investigated. As a component of tissues and organs, collagen"s structure and function is inextricably intertwined with that of the many other matrix components; to what extent do these noncollagenous components affect its nonlinear properties? To answer this, we investigated SHG in two different collagenous tissues, liver and cartilage; in addition we looked at the effect of progressive pathological changes in these tissues on SHG. At the other end of the spectrum, we studied collagen organized at the minimal level of complexity necessary for SHG detection: fibrils generated from solutions containing only a single type of collagen. Data obtained from these studies suggest that collagen"s strong nonlinear susceptibility, a property no other biologically significant macromolecule shares to the same degree, may serve as more than the basis of a novel imaging device for soft tissue. Collagen"s nonlinear optical properties in conjunction with its vast capacity for self-initiated conformational change--through self-assembly, site recognition, post-translational modification, and the like -make it an attractive candidate molecule for any of several demanding engineering applications, such as nanopatterning.

  19. Anharmonic free energies and phonon dispersions from the stochastic self-consistent harmonic approximation: Application to platinum and palladium hydrides

    NASA Astrophysics Data System (ADS)

    Errea, Ion; Calandra, Matteo; Mauri, Francesco

    2014-02-01

    Harmonic calculations based on density-functional theory are generally the method of choice for the description of phonon spectra of metals and insulators. The inclusion of anharmonic effects is, however, delicate as it relies on perturbation theory requiring a considerable amount of computer time, fast increasing with the cell size. Furthermore, perturbation theory breaks down when the harmonic solution is dynamically unstable or the anharmonic correction of the phonon energies is larger than the harmonic frequencies themselves. We present here a stochastic implementation of the self-consistent harmonic approximation valid to treat anharmonicity at any temperature in the nonperturbative regime. The method is based on the minimization of the free energy with respect to a trial density matrix described by an arbitrary harmonic Hamiltonian. The minimization is performed with respect to all the free parameters in the trial harmonic Hamiltonian, namely, equilibrium positions, phonon frequencies, and polarization vectors. The gradient of the free energy is calculated following a stochastic procedure. The method can be used to calculate thermodynamic properties, dynamical properties, and even anharmonic corrections to the Eliashberg function of the electron-phonon coupling. The scaling with the system size is greatly improved with respect to perturbation theory. The validity of the method is demonstrated in the strongly anharmonic palladium and platinum hydrides. In both cases, we predict a strong anharmonic correction to the harmonic phonon spectra, far beyond the perturbative limit. In palladium hydrides, we calculate thermodynamic properties beyond the quasiharmonic approximation, while in PtH, we demonstrate that the high superconducting critical temperatures at 100 GPa predicted in previous calculations based on the harmonic approximation are strongly suppressed when anharmonic effects are included.

  20. Third harmonic transmit phasing for SNR improvement in tissue harmonic imaging with Golay-encoded excitation.

    PubMed

    Shen, Che-Chou; Shi, Tai-Yu

    2011-07-01

    Ultrasound tissue harmonic signal generally provides superior image quality as compared to the linear signal. However, since the generation of the tissue harmonic signal is based on finite amplitude distortion of the propagating waveform, the penetration and the sensitivity in tissue harmonic imaging are markedly limited because of the low signal-to-noise ratio (SNR). The method of third harmonic (3f(0)) transmit phasing can improve the tissue harmonic SNR by transmitting at both the fundamental (2.25MHz) and the 3f(0) (6.75MHz) frequencies to achieve mutual enhancement between the frequency-sum and the frequency-difference components of the second harmonic signal. To further increase the SNR without excessive transmit pressure, coded excitation can be incorporated in 3f(0) transmit phasing to boost the tissue harmonic generation. Our analyses indicate that the phase-encoded Golay excitation is suitable in 3f(0) transmit phasing due to its superior transmit bandwidth efficiency. The resultant frequency-sum and frequency-difference components of tissue harmonic signal can be simultaneously Golay-encoded for SNR improvement. The increase of the main-lobe signal with the Golay excitation in 3f(0) transmit phasing are consistent between the tissue harmonic measurements and the simulations. B-mode images of the speckle generating phantom also demonstrate the increases of tissue harmonic SNR for about 11dB without noticeable compression artifacts. For tissue harmonic imaging in combination with the 3f(0) transmit phasing method, the Golay excitation can provide further SNR improvement. Meanwhile, the axial resolution can be effectively restored by pulse compression while the lateral resolution remains unchanged. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. [Globalization of clinical trials].

    PubMed

    Akaza, Hideyuki; Fukuoka, Masahiro; Ohtsu, Atsushi; Usami, Michiyuki; Ikeda, Tadashi; Aiba, Keisuke; Isonishi, Seiji; Ohashi, Yasuo; Saijo, Nagahiro; Sone, Saburo; Tsukagoshi, Shigeru; Tsuruo, Takashi; Kato, Masuhiro; Mikami, Osamu; Dong, Rui-Ping; von Euler, Mikael; Blackledge, George; Stribling, Don

    2003-04-01

    Based on reviews of the Japanese clinical trial situation in lung cancer, gastric cancer, prostate cancer and breast cancer, it was clear that much progress has been made in short time. There are considerable differences between Japan and the West and also differences between clinical areas in Japan. For regulatory purposes bridging studies have become increasingly important. Use of identical protocols are required for effective bridging. Participations in global phase III trials is the best way of achieving registration in Japan. For successful global trials in Japan it is important to include Japanese investigators in the preparation of the protocol and to recognise the challenges facing such a project. Clinical practice in diagnosis and treatment have many differences, thus it is recommended to have clear and detailed information in the protocol. Hard end points like survival are important since they are not biased by cultural differences. There are clear difficulties with HE or QOL outcomes. The emergence of focus on evidence based medicine is also happening in Japan and will help to harmonize documentation across the world. For large adjuvant or prevention cancer global trials are essential. To facilitate global studies further development of infrastructure is necessary in Japan. Use of electronic data capture web based communication etc. will help overcome communication difficulties. Other improvements that will make Japanese participation in global trials easier and better include establishment of clinical trial centre at each hospital, introduction of trial coordinators or study nurses and an improved collaboration with company staff. A critical issue that also need addressing is agreement of centre target recruitment. We need to introduce a new flexible system in Japan if participation in global trial is to be optimised. If we can address these issues Japanese investigators and collaborative groups should be able to initiate and lead global trials in the

  2. Beam Conditioning and Harmonic Generation in Free ElectronLasers

    SciTech Connect

    Charman, A.E.; Penn, G.; Wolski, A.; Wurtele, J.S.

    2004-07-05

    The next generation of large-scale free-electron lasers (FELs) such as Euro-XFEL and LCLS are to be devices which produce coherent X-rays using Self-Amplified Spontaneous Emission (SASE). The performance of these devices is limited by the spread in longitudinal velocities of the beam. In the case where this spread arises primarily from large transverse oscillation amplitudes, beam conditioning can significantly enhance FEL performance. Future X-ray sources may also exploit harmonic generation starting from laser-seeded modulation. Preliminary analysis of such devices is discussed, based on a novel trial-function/variational-principle approach, which shows good agreement with more lengthy numerical simulations.

  3. Modified ADALINE algorithm for harmonic estimation and selective harmonic elimination in inverters

    NASA Astrophysics Data System (ADS)

    Vasumathi, B.; Moorthi, S.

    2011-11-01

    In digital signal processing, algorithms are very well developed for the estimation of harmonic components. In power electronic applications, an objective like fast response of a system is of primary importance. An effective method for the estimation of instantaneous harmonic components, along with conventional harmonic elimination technique, is presented in this article. The primary function is to eliminate undesirable higher harmonic components from the selected signal (current or voltage) and it requires only the knowledge of the frequency of the component to be eliminated. A signal processing technique using modified ADALINE algorithm has been proposed for harmonic estimation. The proposed method stays effective as it converges to a minimum error and brings out a finer estimation. A conventional control based on pulse width modulation for selective harmonic elimination is used to eliminate harmonic components after its estimation. This method can be applied to a wide range of equipment. The validity of the proposed method to estimate and eliminate voltage harmonics is proved with a dc/ac inverter as a simulation example. Then, the results are compared with existing ADALINE algorithm for illustrating its effectiveness.

  4. The impact of harmonization on ELISPOT assay performance.

    PubMed

    Janetzki, Sylvia; Britten, Cedrik M

    2012-01-01

    During more than 25 years of application in immunological sciences, ELISPOT has been established as a routine, robust, versatile, and reliable assay. From basic research to clinical immune monitoring, ELISPOT is being used to address the quantification and (to a lesser extent) functional characterization of immune cells secreting different molecules in the context of health and disease, immune intervention, and therapy in humans and other species [Kalyuzhny (Ed.) (2005) Handbook of Elispot: methods and protocols, Vol. 302, Humana Press Inc., Totowa, NJ]. Over the last decade, ELISPOT assays have been increasingly implemented as an immune-monitoring tool in clinical trials [Schmittel et al. J Immunother 23:289-295, 2000; Whiteside Immunol Invest 29:149-162, 2000; Nagata et al. Ann N Y Acad Sci 1037:10-15, 2004; Cox et al. (2005) Cellular immune assays for evaluation of vaccine efficacy in developing countries., In Manual of Clinical Immunology Laboratory (Rose, N. R., Hamilton, R. G., and Detrick, B., Eds.), p 301, ASM Press, Washington, DC; Cox et al. Methods 38:274-282, 2006]. While the principles of the original protocol have changed little since its first introduction [Czerkinsky J Immunol Methods 110:29-36, 1988], individual laboratories have adapted assay procedures based on experimental needs, availability of reagents and equipment, obtained recommendations, and gained experience, leading to a wide disparity of applied ELISPOT protocols with inevitable consequences. This chapter addresses the resulting challenges for ELISPOT use in clinical trial settings, and discusses the influence of harmonization strategies as a tool for overcoming these challenges. Furthermore, harmonization is discussed in the context of assay standardization and validation strategies.

  5. Development of a HACS User Interface Module.

    DTIC Science & Technology

    1981-09-30

    ISRC)/1O ISRC=LIST(I ,2)-10*ITYP-ISRC JSRC=ISRC+1 IX=LIST( IP6 ) TAG=UNIT( ISYSPITYP) C C -------- IF FIELD IS REAL, APPLY OUTPUT CONVERSION AND DISPLAY...BNCONCENTRPBHATION VSp8H TIME ATP 18H A FIXEDP’H POINT -p8H MODEL C/ ODATA (PTIT (I)iI= IP6 )/8HMAX GROUy8HND CONC v8HVS TIME/P 18HDISTANCEPBH

  6. Possible role of cochlear nonlinearity in the detection of mistuning of a harmonic component in a harmonic complex

    NASA Astrophysics Data System (ADS)

    Stoelinga, Christophe; Heo, Inseok; Long, Glenis; Lee, Jungmee; Lutfi, Robert; Chang, An-Chieh

    2015-12-01

    The human auditory system has a remarkable ability to "hear out" a wanted sound (target) in the background of unwanted sounds. One important property of sound which helps us hear-out the target is inharmonicity. When a single harmonic component of a harmonic complex is slightly mistuned, that component is heard to separate from the rest. At high harmonic numbers, where components are unresolved, the harmonic segregation effect is thought to result from detection of modulation of the time envelope (roughness cue) resulting from the mistuning. Neurophysiological research provides evidence that such envelope modulations are represented early in the auditory system, at the level of the auditory nerve. When the mistuned harmonic is a low harmonic, where components are resolved, the harmonic segregation is attributed to more centrally-located auditory processes, leading harmonic components to form a perceptual group heard separately from the mistuned component. Here we consider an alternative explanation that attributes the harmonic segregation to detection of modulation when both high and low harmonic numbers are mistuned. Specifically, we evaluate the possibility that distortion products in the cochlea generated by the mistuned component introduce detectable beating patterns for both high and low harmonic numbers. Distortion product otoacoustic emissions (DPOAEs) were measured using 3, 7, or 12-tone harmonic complexes with a fundamental frequency (F0) of 200 or 400 Hz. One of two harmonic components was mistuned at each F0: one when harmonics are expected to be resulted and the other from unresolved harmonics. Many non-harmonic DPOAEs are present whenever a harmonic component is mistuned. These non-harmonic DPOAEs are often separated by the amount of the mistuning (ΔF). This small frequency difference will generate a slow beating pattern at ΔF, because this beating is only present when a harmonic component is mistuned, it could provide a cue for behavioral detection

  7. High-harmonic spectroscopy of molecular isomers

    SciTech Connect

    Wong, M. C. H.; Brichta, J.-P.; Bhardwaj, V. R.; Spanner, M.; Patchkovskii, S.

    2011-11-15

    We demonstrate that high-order-harmonic generation (HHG) spectroscopy can be used to probe stereoisomers of randomly oriented 1,2-dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and 2-butene (C{sub 4}H{sub 8}). The high-harmonic spectra of these isomers are distinguishable over a range of laser intensities and wavelengths. Time-dependent numerical calculations of angle-dependent ionization yields for 1,2-dichloroethylene suggest that the harmonic spectra of molecular isomers reflect differences in their strong-field ionization. The subcycle ionization yields for the cis isomer are an order of magnitude higher than those for the trans isomer. The sensitivity in discrimination of the harmonic spectra of cis- and trans- isomers is greater than 8 and 5 for 1,2-dichloroethylene and 2-butene, respectively. We show that HHG spectroscopy cannot differentiate the harmonic spectra of the two enantiomers of the chiral molecule propylene oxide (C{sub 3}H{sub 6}O).

  8. Nonlinear harmonic generation in the STARS FEL

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Goldammer, K.; Kamps, T.; Knobloch, J.; Kuske, B.; Leitner, T.; Meseck, A.

    2008-08-01

    BESSY proposes to build STARS, an FEL to demonstrate cascaded High Gain Harmonic Generation (HGHG). In two HGHG stages, a laser source of 700-900 nm is converted down to a wavelength of 40-70 nm. The STARS facility consists of a normal-conducting RF photoinjector, three superconducting TESLA-type acceleration modules, a magnetic bunch compressor and two stages of HGHG, each consisting of a modulator, dispersive chicane and a radiator. At the entrance of the undulator section, the beam energy is 325 MeV and the peak current is about 500 A. With these parameters, the STARS FEL reaches saturation with a peak power of 100-350 MW. A superradiant mode is also foreseen which boosts the radiation power to the GW-level. Due to nonlinear harmonic generation (NHG), free electron lasers also radiate coherently at higher harmonics of the FEL resonant frequency. STARS can hence extend its output range to even shorter wavelengths. This paper presents studies of the STARS harmonic content in the wavelength range of 6-20 nm. Seeding with high harmonic generation pulses at 32 nm is also discussed.

  9. Promoting clinical and laboratory interaction by harmonization.

    PubMed

    Plebani, Mario; Panteghini, Mauro

    2014-05-15

    The lack of interchangeable results in current practice among clinical laboratories has underpinned greater attention to standardization and harmonization projects. Although the focus was mainly on the standardization and harmonization of measurement procedures and their results, the scope of harmonization goes beyond method and analytical results: it includes all other aspects of laboratory testing, including terminology and units, report formats, reference limits and decision thresholds, as well as test profiles and criteria for the interpretation of results. In particular, as evidence collected in last decades demonstrates that pre-pre- and post-post-analytical steps are more vulnerable to errors, harmonization initiatives should be performed to improve procedures and processes at the laboratory-clinical interface. Managing upstream demand, down-stream interpretation of laboratory results, and subsequent appropriate action through close relationships between laboratorians and clinicians remains a crucial issue of the laboratory testing process. Therefore, initiatives to improve test demand management from one hand and to harmonize procedures to improve physicians' acknowledgment of laboratory data and their interpretation from the other hand are needed in order to assure quality and safety in the total testing process.

  10. High-harmonic generation in amorphous solids

    DOE PAGES

    You, Yong Sing; Yin, Yanchun; Wu, Yi; ...

    2017-09-28

    High-harmonic generation in isolated atoms and molecules has been widely utilized in extreme ultraviolet photonics and attosecond pulse metrology. Recently, high-harmonic generation has been observed in solids, which could lead to important applications such as all-optical methods to image valance charge density and reconstruct electronic band structures, as well as compact extreme ultraviolet light sources. So far these studies are confined to crystalline solids; therefore, decoupling the respective roles of long-range periodicity and high density has been challenging. Here we report the observation of high-harmonic generation from amorphous fused silica. We also decouple the role of long-range periodicity by comparingmore » harmonics generated from fused silica and crystalline quartz, which contain the same atomic constituents but differ in long-range periodicity. These results advance current understanding of the strong-field processes leading to high-harmonic generation in solids with implications for the development of robust and compact extreme ultraviolet light sources.« less

  11. Harmonic Inverse Free Electron Laser Micro-Buncher

    NASA Astrophysics Data System (ADS)

    Pottorf, S.; Wang, X. J.

    2002-04-01

    The Inverse Free Electron (IFEL) and its applications are first briefly reviewed. The concept of harmonic IFEL was proposed for electron beam micro-bunching. A tightly micro-bunched electron beam could be used either as a laser accelerator injector or for femto-second X-ray generation by ultra-high harmonic radiation. For a planar undulator, the electron beam is strongly coupled to both the fundamental and odd harmonic if the undulator parameter is greater than 1, K > 1. The 1-D equation of motion for the IFEL was first extended to the third harmonic. 1-D simulations were performed for both fundamental only IFEL and harmonic IFEL. Two configurations of harmonic IFEL were considered. First, a single undulator with both fundamental and third harmonic IFEL presented simultaneously was studied. Second, a configuration employing a fundamental IFEL followed by a third harmonic IFEL. Better and efficient bunching was achieved for both harmonic IFEL compared to the fundamental IFEL only.

  12. Theory of harmonic dissipation in disordered solids

    NASA Astrophysics Data System (ADS)

    Damart, T.; Tanguy, A.; Rodney, D.

    2017-02-01

    Mechanical spectroscopy, i.e., cyclic deformations at varying frequencies, is used theoretically and numerically to compute dissipation in model glasses. From a normal mode analysis, we show that in the high-frequency terahertz regime where dissipation is harmonic, the quality factor (or loss angle) can be expressed analytically. This expression is validated through nonequilibrium molecular dynamics simulations applied to a model of amorphous silica (SiO2). Dissipation is shown to arise from nonaffine relaxations triggered by the applied strain through the excitation of vibrational eigenmodes that act as damped harmonic oscillators. We discuss an asymmetry vector field, which encodes the information about the structural origin of dissipation computed by mechanical spectroscopy. In the particular case of silica, we find that the motion of oxygen atoms, which induce a deformation of the Si-O-Si bonds, is the main contributor to harmonic energy dissipation.

  13. Optical Third-Harmonic Generation in Graphene

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Young; Dadap, Jerry I.; Petrone, Nicholas; Yeh, Po-Chun; Hone, James; Osgood, Richard M., Jr.

    2013-04-01

    We report strong third-harmonic generation in monolayer graphene grown by chemical vapor deposition and transferred to an amorphous silica (glass) substrate; the photon energy is in three-photon resonance with the exciton-shifted van Hove singularity at the M point of graphene. The polarization selection rules are derived and experimentally verified. In addition, our polarization- and azimuthal-rotation-dependent third-harmonic-generation measurements reveal in-plane isotropy as well as anisotropy between the in-plane and out-of-plane nonlinear optical responses of graphene. Since the third-harmonic signal exceeds that from bulk glass by more than 2 orders of magnitude, the signal contrast permits background-free scanning of graphene and provides insight into the structural properties of graphene.

  14. Relativistic harmonics for turbulent wakefield diagnostics

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Yasuhiro; Chen, Shih-Hung

    2017-06-01

    The propagation properties of relativistic harmonics excited in a plasma with an intense laser pulse is investigated theoretically and numerically. Focusing on the frequency separation, a cold electron fluid model in two spatial dimension is discussed to obtain the harmonic amplitude. The theoretical predictions are verified by performing particle-in-cell simulations in two spatial dimensions. When the laser amplitude is large, the strong ponderomotive force expels the electrons, creating a large amplitude density structures associated with the wakefield. The harmonics propagate obliquely with respect to the laser propagation direction, which is well represented by the structure of the high density layer resulting from the transverse poderomotive force. We also discuss a possible experimental setup to observe the density structures relevant to wakefield.

  15. Coded excitation for ultrasound tissue harmonic imaging.

    PubMed

    Song, Jaehee; Kim, Sangwon; Sohn, Hak-Yeol; Song, Tai-Kyong; Yoo, Yang Mo

    2010-05-01

    Coded excitation can improve the signal-to-noise ratio (SNR) in ultrasound tissue harmonic imaging (THI). However, it could suffer from the increased sidelobe artifact caused by incomplete pulse compression due to the spectral overlap between the fundamental and harmonic components of ultrasound signal after nonlinear propagation in tissues. In this paper, three coded tissue harmonic imaging (CTHI) techniques based on bandpass filtering, power modulation and pulse inversion (i.e., CTHI-BF, CTHI-PM, and CTHI-PI) were evaluated by measuring the peak range sidelobe level (PRSL) with varying frequency bandwidths. From simulation and in vitro studies, the CTHI-PI outperforms the CTHI-BF and CTHI-PM methods in terms of the PRSL, e.g., -43.5dB vs. -24.8dB and -23.0dB, respectively. Copyright 2010 Elsevier B.V. All rights reserved.

  16. Optical High Harmonic Generation in C60

    NASA Astrophysics Data System (ADS)

    Zhang, Guoping

    2005-03-01

    C60 et al. Physical Review Letters Physical Review B High harmonic generation (HHG) requires a strong laser field, but in a relatively weak laser field is sufficient. Numerical results presented here show while its low order harmonics result from the laser field, its high order ones are mainly from the multiple excitations. Since high order harmonics directly correlate electronic transitions, the HHG spectrum accurately measures transition energies. Therefore, is not only a promising material for HHG, but may also present an opportunity to develop HHG into an electronic structure probing tool. References: G. P. Zhang, 91, 176801 (2003); G. P. Zhang and T. F. George, 68, 165410 (2003); P. B. Corkum, 71, 1994 (1993); G. P. Zhang and Thomas F. George, 93, 147401 (2004); H. Niikura ,ature 417, 917 (2002); ibid. 421, 826 (2003); Y. Mairesse ,cience 302, 1540 (2003); A. Baltuska ,ature 421, 611 (2003).

  17. Degradation in finite-harmonic subcarrier demodulation

    NASA Technical Reports Server (NTRS)

    Feria, Y.; Townes, S.; Pham, T.

    1995-01-01

    Previous estimates on the degradations due to a subcarrier loop assume a square-wave subcarrier. This article provides a closed-form expression for the degradations due to the subcarrier loop when a finite number of harmonics are used to demodulate the subcarrier, as in the case of the buffered telemetry demodulator. We compared the degradations using a square wave and using finite harmonics in the subcarrier demodulation and found that, for a low loop signal-to-noise ratio, using finite harmonics leads to a lower degradation. The analysis is under the assumption that the phase noise in the subcarrier (SC) loop has a Tikhonov distribution. This assumption is valid for first-order loops.

  18. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io-L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  19. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  20. The harmonic oscillator and nuclear physics

    NASA Technical Reports Server (NTRS)

    Rowe, D. J.

    1993-01-01

    The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.

  1. Superresonant Radiation Stimulated by Higher Harmonics

    NASA Astrophysics Data System (ADS)

    Lourés, Cristian Redondo; Roger, Thomas; Faccio, Daniele; Biancalana, Fabio

    2017-01-01

    Solitons propagating in media with higher-order dispersion will shed radiation known as resonant radiation, with applications in frequency broadening, deep UV sources for spectroscopy, and fundamental studies of soliton physics. Using a recently proposed equation that models the behavior of ultrashort optical pulses in nonlinear media using the analytic signal, we find that the resonant radiation associated with the third-harmonic generation term of the equation is parametrically stimulated with an unprecedented gain. Resonant radiation levels, typically only a small fraction of the soliton, are now as intense as the soliton itself. The mechanism is universal and works also in normal dispersion and with harmonics higher than the third. We report experimental hints of this superresonant radiation stimulated by the fifth harmonic in diamond.

  2. Microscopic optical buffering in a harmonic potential

    PubMed Central

    Sumetsky, M.

    2015-01-01

    In the early days of quantum mechanics, Schrödinger noticed that oscillations of a wave packet in a one-dimensional harmonic potential well are periodic and, in contrast to those in anharmonic potential wells, do not experience distortion over time. This original idea did not find applications up to now since an exact one-dimensional harmonic resonator does not exist in nature and has not been created artificially. However, an optical pulse propagating in a bottle microresonator (a dielectric cylinder with a nanoscale-high bump of the effective radius) can exactly imitate a quantum wave packet in the harmonic potential. Here, we propose a tuneable microresonator that can trap an optical pulse completely, hold it as long as the material losses permit, and release it without distortion. This result suggests the solution of the long standing problem of creating a microscopic optical buffer, the key element of the future optical signal processing devices. PMID:26689546

  3. Second International Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo (Editor); Wolf, Kurt Bernardo (Editor)

    1995-01-01

    The Second International Workshop on Harmonic Oscillators was held at the Hotel Hacienda Cocoyoc from March 23 to 25, 1994. The Workshop gathered 67 participants; there were 10 invited lecturers, 30 plenary oral presentations, 15 posters, and plenty of discussion divided into the five sessions of this volume. The Organizing Committee was asked by the chairman of several Mexican funding agencies what exactly was meant by harmonic oscillators, and for what purpose the new research could be useful. Harmonic oscillators - as we explained - is a code name for a family of mathematical models based on the theory of Lie algebras and groups, with applications in a growing range of physical theories and technologies: molecular, atomic, nuclear and particle physics; quantum optics and communication theory.

  4. Xe/+/ -induced ion-cyclotron harmonic waves

    NASA Astrophysics Data System (ADS)

    Jones, D.

    Xenon ion sources on an ejectable package separated from the main payload during the flights of Porcupine rockets F3 and F4 which were launched from Kiruna, Sweden on March 19 and 31, 1979, respectively. The effects of the xenon ion beam, detected by the LF (f less than 16 kHz) wideband electric field experiment and analyzed by using a sonograph, are discussed. Particular attention is given to the stimulation of the ion-cyclotron harmonic waves which are usually linked to the local proton gyro-frequency, but are sometimes related to half that frequency. It was found that in a plasma dominated by O(+) ions, a small amount (1-10%) of protons could cause an effect such that the O(+) cyclotron harmonic waves are set up by the hydrogen ions, the net result being the observation of harmonic emissions separated by the hydrogen ion gyro frequency.

  5. High harmonic phase in molecular nitrogen

    SciTech Connect

    McFarland, Brian K.

    2009-10-17

    Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N{sub 2}. The phase is measured interferometrically by beating the N{sub 2} harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2{pi} is observed in the vicinity of the HHG spectral minimum, where a shift of {pi} had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N{sub 2} that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.

  6. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  7. Second Harmonic Hectometric Radio Emission at Jupiter

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Groene, J. B.

    1998-01-01

    Galileo has been in orbit around Jupiter since December 1995. The plasma wave instrument on board the spacecraft has occasionally detected a rotationally modulated attenuation band in the hectometric (HOM) emission that most likely is due to scattering of the radiation from density fluctuations along the Io L-shell, as reported earlier. The occurrence of the attenuation band is likely to be dependent on Io activity and the presence of density scattering centers along the Io-L-shell as well as the location of the source region. Some of the attenuation bands show clear indications of second harmonic emission. Without polarization measurements, it is difficult to place constraints on the local generation conditions based on the cyclotron maser instability, but the results imply that second harmonic emission could be present in the decametric (DAM) radiation as well. A survey of the data has revealed about 30 examples of second harmonic HOM.

  8. GRACE Harmonic and Mascon Solutions at JPL

    NASA Astrophysics Data System (ADS)

    Watkins, M. M.; Yuan, D.; Kuang, D.; Bertiger, W.; Kim, M.; Kruizinga, G. L.

    2005-12-01

    Gravity field solutions at JPL over the past few years have explored use of range, range-rate, and range-acceleration K/Ka-band satellite-satellite data types (with and without GPS), and with both spherical harmonic and mascon-type local mass representations. Until recently, resource and computing limitations have limited the scope of our mascon and other local solutions to a few months and/or small spatial regions and the standard GRACE products have remained spherical harmonic fields. The use of a new very large (~500 node) beowulf machine at JPL is now enabling a wider range of solutions over longer time spans and deeper understanding of their characteristics. These include much higher spherical harmonic degrees, mascons, and hybrids of the two. We will present the current status for several solution types, strengths and weaknesses of each, and our assessments of limiting errors including data noise and aliasing sensitivity.

  9. On the symplectic structure of harmonic superspace

    SciTech Connect

    Kachkachi, M.; Saidi, E.H. )

    1992-11-10

    In this paper, the symplectic properties of harmonic superspace are studied. It is shown that Diff(S[sup 2]) is isomorphic to Diff[sub 0](S[sup 3])/Ab(Diff[sub 0](S[sup 3])), where Diff[sub 0](S[sup 3]) is the group of the diffeomorphisms of S[sup 3] preserving the Cartan charge operator D[sup 0] and Ab(Diff[sub 0](S[sup 3])) is its Abelian subgroup generated by the Cartan vectors L[sub 0] = w[sup 0]D[sup 0]. The authors show also that the eigenvalue equation D[sup 0] [lambda](z) = 0 defines a symplectic structure in harmonic superspace, and the authors calculate the corresponding algebra. The general symplectic invariant coupling of the Maxwell prepotential is constructed in both flat and curved harmonic superspace. Other features are discussed.

  10. Spherical harmonic analysis of steady photospheric flows

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.

    1987-01-01

    A technique is presented in which full disk Doppler velocity measurements are analyzed using spherical harmonic functions to determine the characteristics of the spectrum of spherical harmonic modes and the nature of steady photospheric flows. Synthetic data are constructed in order to test the technique. In spite of the mode mixing due to the lack of information about the motions on the backside of the sun, solar rotation and differential rotation can be accurately measured and monitored for secular changes, and meridional circulations with small amplitudes can be measured. Furthermore, limb shift measurements can be accurately obtained, and supergranules can be fully resolved and separated from giant cells by their spatial characteristics.

  11. Nonlinear harmonic generation in distributed optical klystrons

    SciTech Connect

    H.P. Freund; George R. Neil

    2001-12-01

    A distributed optical klystron has the potential for dramatically shortening the total interaction length in high-gain free-electron lasers (INP 77-59, Novosibirsk, 1977; Nucl. Instr. and Meth A 304 (1991) 463) in comparison to a single-wiggler-segment configuration. This shortening can be even more dramatic if a nonlinear harmonic generation mechanism is used to reach the desired wavelength. An example operating at a 4.5{angstrom} fundamental and a 1.5{angstrom} harmonic is discussed.

  12. Dark-field third-harmonic imaging

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, L. V.; Lanin, A. A.; Fedotov, I. V.; Ivashkina, O. I.; Zots, M. A.; Fedotov, A. B.; Anokhin, K. V.; Zheltikov, A. M.

    2013-08-01

    Coherent cancellation of third-harmonic generation (THG) in a tightly focused laser beam is shown to enable a label-free imaging of individual neurons in representative brain tissues. The intrinsic coherence of third-harmonic buildup and cancellation combined with the nonlinear nature of the process enhances the locality of the dark signal in THG, translating into a remarkable sharpness of dark-field THG images. Unique advantages of this technique for high-contrast subcellular-resolution neuroimaging are demonstrated by comparing THG images of hippocampus and somatosensory cortex in a mouse brain with images visualizing fluorescent protein biomarkers.

  13. Broadband beam shaping with harmonic diffractive optics.

    PubMed

    Singh, Manisha; Tervo, Jani; Turunen, Jari

    2014-09-22

    We consider spatial shaping of broadband (either stationary or pulsed) spatially coherent light, comparing refractive, standard diffractive, and harmonic diffractive (modulo 2πM) elements. Considering frequency-integrated target profiles we show that, contrary to common belief, standard diffractive (M = 1) elements work reasonably well for, e.g., Gaussian femtosecond pulses and spatially coherent amplified-spontaneous-emission sources such as superluminescent diodes. It is also shown that harmonic elements with M ≥ 5 behave in essentially the same way as refractive elements and clearly outperform standard diffractive elements for highly broadband light.

  14. Quantum stochastic thermodynamic on harmonic networks

    NASA Astrophysics Data System (ADS)

    Deffner, Sebastian

    2016-01-01

    Fluctuation theorems are symmetry relations for the probability to observe an amount of entropy production in a finite-time process. In a recent paper Pigeon et al (2016 New. J. Phys. 18 013009) derived fluctuation theorems for harmonic networks by means of the large deviation theory. Their novel approach is illustrated with various examples of experimentally relevant systems. As a main result, however, Pigeon et al provide new insight how to consistently formulate quantum stochastic thermodynamics, and provide new and robust tools for the study of the thermodynamics of quantum harmonic networks.

  15. Quantum stochastic thermodynamic on harmonic networks

    DOE PAGES

    Deffner, Sebastian

    2016-01-04

    Fluctuation theorems are symmetry relations for the probability to observe an amount of entropy production in a finite-time process. In a recent paper Pigeon et al (2016 New. J. Phys. 18 013009) derived fluctuation theorems for harmonic networks by means of the large deviation theory. Furthermore, their novel approach is illustrated with various examples of experimentally relevant systems. As a main result, however, Pigeon et al provide new insight how to consistently formulate quantum stochastic thermodynamics, and provide new and robust tools for the study of the thermodynamics of quantum harmonic networks.

  16. Application of harmonic detection technology in methane telemetry

    NASA Astrophysics Data System (ADS)

    Huo, Yuehua; Fan, Weiqiang

    2017-08-01

    Methane telemetry plays a vital role in ensuring the safe production of coal mines and monitoring the leakage of natural gas pipelines. Harmonic detection is the key technology of methane telemetry accuracy and sensitivity, but the current telemetry distance is short, the relationship between different modulation parameters is complex, and the harmonic signal is affected by noise interference. These factors seriously affect the development of harmonic detection technology. In this paper, the principle of methane telemetry based on harmonic detection technology is introduced. The present situation and characteristics of harmonic detection technology are expounded. The problems existing in harmonic detection are analyzed. Finally, the future development trend is discussed.

  17. Extraction of small boat harmonic signatures from passive sonar.

    PubMed

    Ogden, George L; Zurk, Lisa M; Jones, Mark E; Peterson, Mary E

    2011-06-01

    This paper investigates the extraction of acoustic signatures from small boats using a passive sonar system. Noise radiated from a small boats consists of broadband noise and harmonically related tones that correspond to engine and propeller specifications. A signal processing method to automatically extract the harmonic structure of noise radiated from small boats is developed. The Harmonic Extraction and Analysis Tool (HEAT) estimates the instantaneous fundamental frequency of the harmonic tones, refines the fundamental frequency estimate using a Kalman filter, and automatically extracts the amplitudes of the harmonic tonals to generate a harmonic signature for the boat. Results are presented that show the HEAT algorithms ability to extract these signatures.

  18. Development of a Standard Protocol for the Harmonic Analysis of Radial Pulse Wave and Assessing Its Reliability in Healthy Humans.

    PubMed

    Chang, Chi-Wei; Chen, Jiang-Ming; Wang, Wei-Kung

    2015-01-01

    This study was aimed to establish a standard protocol and to quantitatively assess the reliability of harmonic analysis of the radial pulse wave measured by a harmonic wave analyzer (TD01C system). Both intraobserver and interobserver assessments were conducted to investigate whether the values of harmonics are stable in successive measurements. An intraclass correlation coefficient (ICC) and a Bland-Altman plot were used for this purpose. For the reliability assessments of the intraobserver and the interobserver, 22 subjects (mean age 45 ± 14 years; 14 males and 8 females) were enrolled. The first eleven harmonics of the radial pulse wave presented excellent repeatability ([Formula: see text] and [Formula: see text]) for the intraobserver assessment and high reproducibility (ICCs range from 0.83 to 0.96 and [Formula: see text]) for the interobserver assessment. The Bland-Altman plot indicated that more than 90% of harmonic values fell within two standard deviations of the mean difference. Thus, we concluded that the harmonic analysis of the radial pulse wave using the TD01C system is a feasible and reliable method to assess a hemodynamic characteristic in clinical trial.

  19. The exact transformation from spherical harmonic to ellipsoidal harmonic coefficients for gravitational field modeling

    NASA Astrophysics Data System (ADS)

    Hu, Xuanyu

    2016-06-01

    The spherical and ellipsoidal harmonic series of the external gravitational potential for a given mass distribution are equivalent in their mutual region of uniform convergence. In an instructive case, the equality of the two series on the common coordinate surface of an infinitely large sphere reveals the exact correspondence between the spherical and ellipsoidal harmonic coefficients. The transformation between the two sets of coefficients can be accomplished via the numerical methods by Walter (Celest Mech 2:389-397, 1970) and Dechambre and Scheeres (Astron Astrophys 387:1114-1122, 2002), respectively. On the other hand, the harmonic coefficients are defined by the integrals of mass density moments in terms of the respective solid harmonics. This paper presents general algebraic formulas for expressing the solid ellipsoidal harmonics as a linear combination of the corresponding solid spherical harmonics. An exact transformation from spherical to ellipsoidal harmonic coefficients is found by incorporating these connecting expressions into the density integral. A computational procedure is proposed for the transformation. Numerical results based on the nearly ellipsoidal Martian moon, Phobos, are presented for validation of the method.

  20. Credentialing for participation in clinical trials

    PubMed Central

    Followill, David S.; Urie, Marcia; Galvin, James M.; Ulin, Kenneth; Xiao, Ying; FitzGerald, Thomas J.

    2012-01-01

    The National Cancer Institute (NCI) clinical cooperative groups have been instrumental over the past 50 years in developing clinical trials and evidence-based clinical trial processes for improvements in patient care. The cooperative groups are undergoing a transformation process to launch, conduct, and publish clinical trials more rapidly. Institutional participation in clinical trials can be made more efficient and include the expansion of relationships with international partners. This paper reviews the current processes that are in use in radiation therapy trials and the importance of maintaining effective credentialing strategies to assure the quality of the outcomes of clinical trials. The paper offers strategies to streamline and harmonize credentialing tools and processes moving forward as the NCI undergoes transformative change in the conduct of clinical trials. PMID:23272300

  1. Geomagnetic main field analysis at the core-mantle boundary - Spherical harmonics compared with harmonic splines

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Kohl, Benjamin C.

    1986-01-01

    An optimum truncation level, N, in a spherical-harmonic analysis of the geomagnetic main field at the core-mantle boundary is determined by harmonic-spline analysis. Specifically, that value of N is found at which the two analyses are closest in a well defined sense and, for that value of N, the 'closeness' of two models is determined. Depending slightly on the definition of closeness, optimum N is found to be either 10 or 11. For those values the two analyses give remarkably similar results, showing that the conveniences of spherical harmonics can be retained with little penalty.

  2. Geomagnetic main field analysis at the core-mantle boundary - Spherical harmonics compared with harmonic splines

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Kohl, Benjamin C.

    1986-01-01

    An optimum truncation level, N, in a spherical-harmonic analysis of the geomagnetic main field at the core-mantle boundary is determined by harmonic-spline analysis. Specifically, that value of N is found at which the two analyses are closest in a well defined sense and, for that value of N, the 'closeness' of two models is determined. Depending slightly on the definition of closeness, optimum N is found to be either 10 or 11. For those values the two analyses give remarkably similar results, showing that the conveniences of spherical harmonics can be retained with little penalty.

  3. Harmonic segregation through mistuning can improve fundamental frequency discrimination.

    PubMed

    Bernstein, Joshua G W; Oxenham, Andrew J

    2008-09-01

    This study investigated the relationship between harmonic frequency resolution and fundamental frequency (f(0)) discrimination. Consistent with earlier studies, f(0) discrimination of a diotic bandpass-filtered harmonic complex deteriorated sharply as the f(0) decreased to the point where only harmonics above the tenth were presented. However, when the odd harmonics were mistuned by 3%, performance improved dramatically, such that performance nearly equaled that found with only even harmonics present. Mistuning also improved performance when alternating harmonics were presented to opposite ears (dichotic condition). In a task involving frequency discrimination of individual harmonics within the complexes, mistuning the odd harmonics yielded no significant improvement in the resolution of individual harmonics. Pitch matches to the mistuned complexes suggested that the even harmonics dominated the pitch for f(0)'s at which a benefit of mistuning was observed. The results suggest that f(0) discrimination performance can benefit from perceptual segregation based on inharmonicity, and that poor performance when only high-numbered harmonics are present is not due to limited peripheral harmonic resolvability. Taken together with earlier results, the findings suggest that f(0) discrimination may depend on auditory filter bandwidths, but that spectral resolution of individual harmonics is neither necessary nor sufficient for accurate f(0) discrimination.

  4. Double-Blind, Randomized, Placebo-Controlled Trial of Metoclopramide for Hypersalivation Associated With Clozapine.

    PubMed

    Kreinin, Anatoly; Miodownik, Chanoch; Mirkin, Vitaly; Gaiduk, Yulia; Yankovsky, Yan; Bersudsky, Yuly; Lerner, Paul P; Bergman, Joseph; Lerner, Vladimir

    2016-06-01

    Hypersalivation is a frequent, disturbing, and uncomfortable adverse effect of clozapine therapy that frequently leads to noncompliance. The aim of this study was to examine the efficacy of metoclopramide (dopamine D2 antagonist, antiemetic medication) as an option for management of hypersalivation associated with clozapine (HAC). A 3-week, double-blind, placebo-controlled trial was conducted in university-based research clinics from January 2012 to May 2014, on 58 inpatients treated with clozapine who were experiencing hypersalivation. The subjects were randomly divided into placebo and metoclopramide groups. The starting dose was 10 mg/d. Participants who did not respond were up-titrated 10 mg/d weekly to a total of 30 mg/d during the third week. The number of placebo capsules was increased accordingly up to 3 capsules per day. Primary outcome was the change from baseline to the end of study in the severity of hypersalivation as measured with the Nocturnal Hypersalivation Rating Scale and the Drooling Severity Scale. Secondary outcomes included Clinical Global Impression of Improvement scale and adverse effect scales. Significant improvement on the Nocturnal Hypersalivation Rating Scale was demonstrated in the metoclopramide group from the end of the second week (P < 0.004), and on the Drooling Severity Scale (P < 0.02) in the third week. Clinical Global Impression-Improvement scale scores revealed major improvement. Twenty subjects (66.7%) treated with metoclopramide reported significant decline or total disappearance of HAC in comparison to 8 patients (28.6%) who received placebo (P = 0.031). No adverse effects to metoclopramide were reported. Metoclopramide was found to be safe and effective for the treatment of HAC.

  5. Mapping from rectangular to harmonic representation

    SciTech Connect

    Schneider, W.; Bateman, G.

    1986-08-01

    An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface average needed for 1-1/2-D transport codes and MHD stability codes from an equilibrium flux function given on a rectangular grid.

  6. Quantum nondemolition measurements of harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Thorne, K. S.; Caves, C. M.; Zimmermann, M.; Sandberg, V. D.; Drever, R. W. P.

    1978-01-01

    Measuring systems to determine the real component of the complex amplitude of a harmonic oscillator are described. This amplitude is constant in the absence of driving forces, and the uncertainty principle accounts for the fact that only the real component can be measured precisely and continuously ('quantum nondemolition measurement'). Application of the measuring systems to the detection of gravitational waves is considered.

  7. Harmonic generation with multiple wiggler schemes

    SciTech Connect

    Bonifacio, R.; De Salvo, L.; Pierini, P.

    1995-02-01

    In this paper the authors give a simple theoretical description of the basic physics of the single pass high gain free electron laser (FEL), describing in some detail the FEL bunching properties and the harmonic generation technique with a multiple-wiggler scheme or a high gain optical klystron configuration.

  8. Energy Statistics in Open Harmonic Networks

    NASA Astrophysics Data System (ADS)

    Benoist, Tristan; Jakšić, Vojkan; Pillet, Claude-Alain

    2017-09-01

    We relate the large time asymptotics of the energy statistics in open harmonic networks to the variance-gamma distribution and prove a full large deviation principle. We consider both Hamiltonian and stochastic dynamics, the later case including electronic RC networks. We compare our theoretical predictions with the experimental data obtained by Ciliberto et al. (Phys. Rev. Lett. 110:180601, 2013).

  9. Light and harmonicity: the golden section

    NASA Astrophysics Data System (ADS)

    Raftopoulos, Dionysios G.

    2015-09-01

    Adhering to Werner Heisenberg's and to the school of Copenhagen's physical philosophy we introduce the localized observer as an absolutely necessary element of a consistent physical description of nature. Thus we have synthesized the theory of the harmonicity of the field of light, which attempts to present a new approach to the events in the human perceptible space. It is an axiomatic theory based on the selection of the projective space as the geometrical space of choice, while its first fundamental hypothesis is none other than special relativity theory's second hypothesis, properly modified. The result is that all our observations and measurements of physical entities always refer not to their present state but rather to a previous one, a conclusion evocative of the "shadows" paradigm in Plato's cave allegory. In the kinematics of a material point this previous state we call "conjugate position", which has been called the "retarded position" by Richard Feynman. We prove that the relation of the present position with its conjugate is ruled by a harmonic tetrad. Thus the relation of the elements of the geometrical (noetic) and the perceptible space is harmonic. In this work we show a consequence of this harmonic relation: the golden section.

  10. Harmonic phase angles used for nanoparticle sensing.

    PubMed

    Shi, Yipeng; Khurshid, Hafsa; Ness, Dylan B; Weaver, John B

    2017-10-04

    A series of techniques have been developed to use magnetic nanoparticles as biosensors to characterize their local microenvironment. Two approaches have been used to obtain quantitative information: model based approaches and scaling based approaches. We have favored scaling based approaches, because approximations made in models can lead to limitations in the accuracy. Currently all the scaling approaches use harmonic ratios to retrieve physical parameters like temperature, viscosity and relaxation time. In this work, we showed that the phase angle of the signal at a single harmonic frequency is an alternative to the ratio. The phase angle is nanoparticle density-independent, and can be used to improve sensitivity, enabling us to measure smaller biomedical effects. With the phase angle as an example, we showed that scaling methods are general and do not depend on specific approximations. We showed that the same scaling techniques can be used with both the phase angle and harmonic ratio because they both depend on the same combinations of physical parameters. Using the phase angle improves the precision and using the combination of phase angles and harmonic ratio provides the best precision.

  11. Group Theory of Covariant Harmonic Oscillators

    ERIC Educational Resources Information Center

    Kim, Y. S.; Noz, Marilyn E.

    1978-01-01

    A simple and concrete example for illustrating the properties of noncompact groups is presented. The example is based on the covariant harmonic-oscillator formalism in which the relativistic wave functions carry a covariant-probability interpretation. This can be used in a group theory course for graduate students who have some background in…

  12. Background independent duals of the harmonic oscillator.

    PubMed

    Husain, Viqar

    2006-06-09

    We show that a class of topological field theories are quantum duals of the harmonic oscillator. This is demonstrated by establishing a correspondence between the creation and annihilation operators and nonlocal gauge invariant observables of the topological field theory. The example is used to discuss some issues concerning background independence and the relation of vacuum energy to the problem of time in quantum gravity.

  13. Harmonic moments of radial viscous fingering patterns

    NASA Astrophysics Data System (ADS)

    Swinney, Harry L.; Leshchiner, Alexander; Thrasher, Matthew; Mineev-Weinstein, Mark

    2006-11-01

    We measure the displacement of oil by air in a Hele-Shaw cell constructed of circular glass plates 288 mm in diameter, separated by a gap of 0.38 mm [1]. Oil is removed from the cell perimeter and is replaced by air that enters through a hole in the bottom plate. High resolution digital imaging is used to track the growth of the air bubble, which develops viscous fingers. We determine the pattern's harmonic moments, which are integrals of integer powers of z = x + iy over the oil domain. The results for the harmonic moments are in accord with Richardson's theory [2], which predicts that harmonic moments should be time invariant in the absence of surface tension. Extending the theory to include surface tension, we obtain from measurements of the time evolution of the harmonic moments a value for the surface tension that is within 10 percent of the accepted value. [1] L. Ristroph, M. Thrasher, M. B. Mineev-Weinstein, and H. L. Swinney, Phys. Rev. E 74, 015201 (2006). [2] S. Richardson, J. Fluid Mechanics 56, 609 (1972).

  14. Group Theory of Covariant Harmonic Oscillators

    ERIC Educational Resources Information Center

    Kim, Y. S.; Noz, Marilyn E.

    1978-01-01

    A simple and concrete example for illustrating the properties of noncompact groups is presented. The example is based on the covariant harmonic-oscillator formalism in which the relativistic wave functions carry a covariant-probability interpretation. This can be used in a group theory course for graduate students who have some background in…

  15. Mapping from rectangular to harmonic representation

    SciTech Connect

    Schneider, W.; Bateman, G.

    1987-07-01

    An algorithm is developed to determine the Fourier harmonics representing the level contours of a scalar function given on a rectangular grid. This method is applied to the problem of computing the flux coordinates and flux surface averages needed for 11/2D transport codes and MHD stability codes from an equilibrium flux function on a rectangular grid. copyright 1987 Academic Press, Inc.

  16. Force-Free Time-Harmonic Plasmoids

    DTIC Science & Technology

    1992-10-01

    and the energy equivalent to a fifty-watt lightbulb burning for five minutes. 37 APPENDIX A THE I = FAR FIELD In this appendix, the far-field...about 15,000 Joules. The wavelength of the harmonic wave would he 101&m; and the energy equivalent to a fifty-watt lightbulb burning for five minutes

  17. Quantum harmonic oscillator in a thermal bath

    NASA Technical Reports Server (NTRS)

    Zhang, Yuhong

    1993-01-01

    The influence functional path-integral treatment of quantum Brownian motion is briefly reviewed. A newly derived exact master equation of a quantum harmonic oscillator coupled to a general environment at arbitrary temperature is discussed. It is applied to the problem of loss of quantum coherence.

  18. Hyperbolic Harmonic Mapping for Surface Registration.

    PubMed

    Shi, Rui; Zeng, Wei; Su, Zhengyu; Jiang, Jian; Damasio, Hanna; Lu, Zhonglin; Wang, Yalin; Yau, Shing-Tung; Gu, Xianfeng

    2016-05-12

    Automatic computation of surface correspondence via harmonic map is an active research field in computer vision, computer graphics and computational geometry. It may help document and understand physical and biological phenomena and also has broad applications in biometrics, medical imaging and motion capture inducstries. Although numerous studies have been devoted to harmonic map research, limited progress has been made to compute a diffeomorphic harmonic map on general topology surfaces with landmark constraints. This work conquers this problem by changing the Riemannian metric on the target surface to a hyperbolic metric so that the harmonic mapping is guaranteed to be a diffeomorphism under landmark constraints. The computational algorithms are based on Ricci flow and nonlinear heat diffusion methods. The approach is general and robust. We employ our algorithm to study the constrained surface registration problem which applies to both computer vision and medical imaging applications. Experimental results demonstrate that, by changing the Riemannian metric, the registrations are always diffeomorphic and achieve relatively high performance when evaluated with some popular surface registration evaluation standards.

  19. Condition for minimal harmonic oscillator action

    NASA Astrophysics Data System (ADS)

    Moriconi, M.

    2017-08-01

    We provide an elementary proof that the action for the physical trajectory of the one-dimensional harmonic oscillator is guaranteed to be a minimum if and only if τ<π/ω , where τ is the elapsed time and ω is the oscillator's natural frequency.

  20. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN...

  1. Harmonic cascade FEL designs for LUX

    SciTech Connect

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  2. Markovian evolution of strongly coupled harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Joshi, Chaitanya; Öhberg, Patrik; Cresser, James D.; Andersson, Erika

    2014-12-01

    We investigate how to model Markovian evolution of coupled harmonic oscillators, each of them interacting with a local environment. When the coupling between the oscillators is weak, dissipation may be modeled using local Lindblad terms for each of the oscillators in the master equation, as is commonly done. When the coupling between oscillators is strong, this model may become invalid. We derive a master equation for two coupled harmonic oscillators that are subject to individual heat baths modeled by a collection of harmonic oscillators and show that this master equation in general contains nonlocal Lindblad terms. We compare the resulting time evolution with that obtained for dissipation through local Lindblad terms for each individual oscillator and show that the evolution is different in the two cases. In particular, the two descriptions give different predictions for the steady state and for the entanglement between strongly coupled oscillators. This shows that when describing strongly coupled harmonic oscillators, one must take great care in how dissipation is modeled and that a description using local Lindblad terms may fail. This may be particularly relevant when attempting to generate entangled states of strongly coupled quantum systems.

  3. A Model for Generative Harmonic Dictation.

    ERIC Educational Resources Information Center

    Bales, W. Kenton

    This BASIC computer program designed to help music theory students practice harmonic dictation generates examples for students to use in a drill and practice approach in developing aural skills. To facilitate the implementation of effective generative algorithms, the author has used a non-linear analytical technique similar to the chord symbol…

  4. A "Step-Up" approach for harmonization.

    PubMed

    Van Uytfanghe, Katleen; De Grande, Linde A; Thienpont, Linda M

    2014-05-15

    According to the measurement paradigm, assays claiming the same measurand should give equivalent results within clinically relevant constraints. The key to accomplish this paradigm is standardization of assays to an SI-traceable reference measurement system. However, measurement results for complex analytes often are not expressed in SI-, but in arbitrary units, defined, for example, by an international conventional measurement standard. Traceability to such a standard mostly does not lead to among assay equivalence. To achieve this, the concept of harmonization has been proposed. We describe here the practical aspects involved with the "Step-Up" design. It essentially comprises a sequence of method comparisons with selected sets of commutable samples. The outcome of each phase allows to decide whether the step-up to the next phase can be set. The harmonization process itself uses a statistically valid location measure as surrogate reference measurement procedure. The design also foresees a protocol for sustaining the first-established harmonization status. For the design to be successful, it is essential that as many assays as possible are involved in the method comparison leading to the harmonization target, and that it can be shown that they sufficiently correlate to that target with consistency of performance over the covered measurement range.

  5. REUSE or Rule Harmonization: Just a Project?

    ERIC Educational Resources Information Center

    Munnich, Monika

    2000-01-01

    Describes the REUSE projects in Germany that were the result of the demand for harmonization of German cataloging rules with AACR2 (Anglo American Cataloging Rules 2). Discusses the comparison of bibliographic data; international authority files; USMARC format; and the trend toward internationality. (Author/LRW)

  6. Harmonization of Clinical Laboratory Test Results.

    PubMed

    2016-02-01

    Clinical laboratory testing is now a global activity with laboratories no longer working in isolation but as regional and national networks, and often at international levels. We now have all of the electronic gadgetry via internet technology at our fingertips to rapidly and accurately measure and report on laboratory testing but are our test results harmonized?

  7. Power Divider for Waveforms Rich in Harmonics

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III

    2005-01-01

    A method for dividing the power of an electronic signal rich in harmonics involves the use of an improved divider topology. A divider designed with this topology could be used, for example, to propagate a square-wave signal in an amplifier designed with a push-pull configuration to enable the generation of more power than could be generated in another configuration.

  8. Control of Differential Mode Harmonic Drive Systems

    NASA Astrophysics Data System (ADS)

    Lemmer, László; Kiss, Bálint

    This paper reports the modeling and control of harmonic drives in differential gearing configuration where none of its shafts is fixed. This configuration makes it possible to solve a control problem where one applies two actuators in order to carry out simultaneous position and torque control on two different axes.

  9. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN...

  10. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN...

  11. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN...

  12. 21 CFR 26.48 - Harmonization.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Harmonization. 26.48 Section 26.48 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL MUTUAL RECOGNITION OF PHARMACEUTICAL GOOD MANUFACTURING PRACTICE REPORTS, MEDICAL DEVICE QUALITY SYSTEM AUDIT REPORTS, AND CERTAIN...

  13. Medicinal products in the European Union--between harmonization and divergence.

    PubMed

    Lojko, Natalia

    2010-03-01

    The rules governing the manufacture and trade in medicinal products in the European Union are, to a large extent, harmonized covering almost the entire life cycle of a medicinal product, starting from the conduct of clinical trials (Directive 2001/20, 2005/28), through manufacture (Directive 2003/94), registration, distribution and pharmacovigilance (Directive 2001/83) to the principles concerning pricing and reimbursement (Directive 89/105). A unified registration procedure has been established with respect to highly innovative medicinal products (Regulation 726/2004). There is also abundant case law of the European Court of Justice concerning medicinal products. The harmonization both judicial and legislative--took place in spite of the lack of explicit competence of the EU as regards healthcare and was based to a large extent on the provisions of economic nature, whose aim was to ensure the unfettered functioning of the internal market. In spite of those harmonization efforts, national rules governing pharmaceuticals are still to a large extent divergent, in particular as regards financing and distribution of medicinal products. This paper explores the level of harmonization of pharmaceutical market in Europe, in particular in the light of the primary competence of the Member States in the field of healthcare and discusses its implications.

  14. Harmonic versus LigaSure hemostasis technique in thyroid surgery: A meta-analysis.

    PubMed

    Upadhyaya, Arun; Hu, Tianpeng; Meng, Zhaowei; Li, Xue; He, Xianghui; Tian, Weijun; Jia, Qiang; Tan, Jian

    2016-08-01

    Harmonic scalpel and LigaSure vessel sealing systems have been suggested as options for saving surgical time and reducing postoperative complications. The aim of the present meta-analysis was to compare surgical time, postoperative complications and other parameters between them in for the open thyroidectomy procedure. Studies were retrieved from MEDLINE, Cochrane Library, EMBASE and ISI Web of Science until December 2015. All the randomized controlled trials (RCTs) comparing Harmonic scalpel and LigaSure during open thyroidectomy were selected. Following data extraction, statistical analyses were performed. Among the 24 studies that were evaluated for eligibility, 7 RCTs with 981 patients were included. The Harmonic scalpel significantly reduced surgical time compared with LigaSure techniques (8.79 min; 95% confidence interval, -15.91 to -1.67; P=0.02). However, no significant difference was observed for the intraoperative blood loss, postoperative blood loss, duration of hospital stay, thyroid weight and serum calcium level postoperatively in either group. The present meta-analysis indicated superiority of Harmonic Scalpel only in terms of surgical time compared with LigaSure hemostasis techniques in open thyroid surgery.

  15. Strongly Dispersive Transient Bragg Grating for High Harmonics

    SciTech Connect

    Farrell, J.; Spector, L.S.; Gaarde, M.B.; McFarland, B.K.; Bucksbaum, P.H.; Guhr, Markus; /SLAC, PULSE /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.

    2010-06-04

    We create a transient Bragg grating in a high harmonic generation medium using two counterpropagating pulses. The Bragg grating disperses the harmonics in angle and can diffract a large bandwidth with temporal resolution limited only by the source size.

  16. Wiggler magnetic field assisted second harmonic generation in clusters

    NASA Astrophysics Data System (ADS)

    Aggarwal, Munish; Vij, Shivani; Kant, Niti

    2015-06-01

    Wiggler magnetic field assisted second harmonic generation in clusters has been investigated theoretically. An intense short-pulse laser propagating through a gas embedded with atomic clusters, converts it into hot plasma balls. For clusters with radius less than one tenth of the laser wavelength, the nonlinear restoration force dominates, which leads to second harmonic generation. The magnetic wiggler provides the uncompensated momentum to second harmonic photon, to make the process of harmonic generation resonant. We explore the impact of laser intensity and cluster size on the efficiency of second harmonic generation. Pulse slippage of second harmonic pulse out of the domain of fundamental laser pulse has been observed on account of group velocity mismatch between the fundamental and second harmonic pulse. Enhancement in the efficiency of the second harmonic is seen for the optimum values of wiggler magnetic field.

  17. Voltage harmonic elimination with RLC based interface smoothing filter

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, K.; Ramachandaramurthy, V. K.

    2015-04-01

    A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.

  18. Complete Vector Spherical Harmonic Expansion for Maxwell's Equations

    ERIC Educational Resources Information Center

    Lambert, R. H.

    1978-01-01

    Conventional expansions of solutions to Maxwell's equations in vector spherical harmonics apply only outside the sources. The complete solution, applying both inside and outside the sources, is given here. Harmonic time dependence is assumed. (Author/GA)

  19. Complete Vector Spherical Harmonic Expansion for Maxwell's Equations

    ERIC Educational Resources Information Center

    Lambert, R. H.

    1978-01-01

    Conventional expansions of solutions to Maxwell's equations in vector spherical harmonics apply only outside the sources. The complete solution, applying both inside and outside the sources, is given here. Harmonic time dependence is assumed. (Author/GA)

  20. Feasibility of 3D harmonic contrast imaging.

    PubMed

    Voormolen, M M; Bouakaz, A; Krenning, B J; Lancée, C T; ten Cate, F J; de Jong, N

    2004-04-01

    Improved endocardial border delineation with the application of contrast agents should allow for less complex and faster tracing algorithms for left ventricular volume analysis. We developed a fast rotating phased array transducer for 3D imaging of the heart with harmonic capabilities making it suitable for contrast imaging. In this study the feasibility of 3D harmonic contrast imaging is evaluated in vitro. A commercially available tissue mimicking flow phantom was used in combination with Sonovue. Backscatter power spectra from a tissue and contrast region of interest were calculated from recorded radio frequency data. The spectra and the extracted contrast to tissue ratio from these spectra were used to optimize the excitation frequency, the pulse length and the receive filter settings of the transducer. Frequencies ranging from 1.66 to 2.35 MHz and pulse lengths of 1.5, 2 and 2.5 cycles were explored. An increase of more than 15 dB in the contrast to tissue ratio was found around the second harmonic compared with the fundamental level at an optimal excitation frequency of 1.74 MHz and a pulse length of 2.5 cycles. Using the optimal settings for 3D harmonic contrast recordings volume measurements of a left ventricular shaped agar phantom were performed. Without contrast the extracted volume data resulted in a volume error of 1.5%, with contrast an accuracy of 3.8% was achieved. The results show the feasibility of accurate volume measurements from 3D harmonic contrast images. Further investigations will include the clinical evaluation of the presented technique for improved assessment of the heart.

  1. Harmonics and instabilities in switching circuits

    SciTech Connect

    Lasseter, R.H.; Dobson, I.; Jalali, S.G. . Coll. of Engineering)

    1993-05-01

    Over the last couple of years there has been significant activity in the development of Flexible AC Transmission Systems (FACTS). Much of this work has been directed towards advanced series compensation (ASC) systems based on a Thyristor Controlled Reactor (TCR) connected in parallel with a fixed capacitor. This results in a controllable series impedance element for use in transmission systems. FACTS devices generate harmonics which interact with the transmission system causing voltage distortions. These distortions can change the operation of such circuits. The authors have found new instabilities in both FACTS and static VAR circuits in which switching times change suddenly, or bifurcate as a system parameter varies slowly. The switching time bifurcation instabilities are explained and their mechanisms are illustrated by both analysis and simulation. The TCR is a periodically operated, nonlinear circuit which may be studied using a Poincare map. The Poincare map is computed and a simple formula for its Jacobian matrix is derived. This formula which describes the stability of the steady state periodic operation of the circuit is used to demonstrate that conventional bifurcations do not occur in this TCR example. The harmonic coupling solution method as developed by Bohmann and Lasseter has been extensively used to compute the steady state solutions of the TCR circuits. In this method, Fourier techniques are used to calculate the system harmonics. By expressing the TCR voltage and current as a Fourier series, a TCR harmonic admittance matrix is constructed and incorporated into a power system providing a general method of computing the power system harmonics. The authors have extended this method to single phase line commutated converters and shown how much circuit may have highly nonlinear and unexpected behavior.

  2. Amplitude-modulated circular-harmonic filter for pattern recognition.

    PubMed

    Chen, X W; Chen, Z P

    1995-02-10

    An amplitude-modulated circular-harmonic filter is proposed for rotation-invariant pattern recognition. We investigate the filter characteristics by varying two design parameters, A(ρ) and B(ρ), and select optimum values to design an amplitude-modulated circular-harmonic filter. When compared with the phase-only circular-harmonic filter, the amplitude-modulated circular-harmonic filter is found to yield a sharper correlation peak, a better noise tolerance, and an improved correlation discrimination.

  3. Reduced Switching Frequency Active Harmonic Elimination for Multilevel Converters

    SciTech Connect

    Du, Zhong; Tolbert, Leon M; Chiasson, John N; Ozpineci, Burak

    2008-01-01

    This paper presents a reduced switching-frequency active-harmonic-elimination method (RAHEM) to eliminate any number of specific order harmonics of multilevel converters. First, resultant theory is applied to transcendental equations to eliminate low-order harmonics and to determine switching angles for a fundamental frequency-switching scheme. Next, based on the number of harmonics to be eliminated, Newton climbing method is applied to transcendental equations to eliminate high-order harmonics and to determine switching angles for the fundamental frequency-switching scheme. Third, the magnitudes and phases of the residual lower order harmonics are computed, generated, and subtracted from the original voltage waveform to eliminate these low-order harmonics. Compared to the active-harmonic-elimination method (AHEM), which generates square waves to cancel high-order harmonics, RAHEM has lower switching frequency. The simulation results show that the method can effectively eliminate all the specific harmonics, and a low total harmonic distortion (THD) near sine wave is produced. An experimental 11-level H-bridge multilevel converter with a field-programmable gate-array controller is employed to experimentally validate the method. The experimental results show that RAHEM does effectively eliminate any number of specific harmonics, and the output voltage waveform has low switching frequency and low THD.

  4. A Look at Damped Harmonic Oscillators through the Phase Plane

    ERIC Educational Resources Information Center

    Daneshbod, Yousef; Latulippe, Joe

    2011-01-01

    Damped harmonic oscillations appear naturally in many applications involving mechanical and electrical systems as well as in biological systems. Most students are introduced to harmonic motion in an elementary ordinary differential equation (ODE) course. Solutions to ODEs that describe simple harmonic motion are usually found by investigating the…

  5. A Comparison of Scalar and Root Harmonic Aural Perception Techniques.

    ERIC Educational Resources Information Center

    Alvarez, Manuel

    1980-01-01

    Seventy-two junior high general music students were taught to identify primary harmonic functions by using either a scalar or root harmonic aural perception technique. Students were then tested with an aural identification battery. The scalar technique appeared to be the more effective procedure for teaching primary harmonic functions. (Author/SJL)

  6. Second-harmonic superprism effect in photonic crystals.

    PubMed

    Centeno, Emmanuel

    2005-05-01

    By exploitation of the nonlinear optical properties of two-dimensional photonic crystals, a second-harmonic superprism effect is demonstrated. The anisotropy of the dispersion curves allows control of the propagation direction of the second-harmonic field. Smooth variations of the fundamental wavelength or the angle of incidence produce a drastic angular shift of the second-harmonic emission.

  7. Harmonization of USMARC, CAN/MARC, and UKMARC.

    ERIC Educational Resources Information Center

    McCallum, Sally H.

    2000-01-01

    Discusses efforts by the Library of Congress, the National Library of Canada, and the British Library to harmonize their respective MARC (Machine Readable Cataloging) formats. Describes the harmonization of USMARC and CAN/MARC and explains why problems make the harmonization with UKMARC not feasible at the present time. (LRW)

  8. A Look at Damped Harmonic Oscillators through the Phase Plane

    ERIC Educational Resources Information Center

    Daneshbod, Yousef; Latulippe, Joe

    2011-01-01

    Damped harmonic oscillations appear naturally in many applications involving mechanical and electrical systems as well as in biological systems. Most students are introduced to harmonic motion in an elementary ordinary differential equation (ODE) course. Solutions to ODEs that describe simple harmonic motion are usually found by investigating the…

  9. Twenty-Four Tuba Harmonics Using a Single Pipe Length

    ERIC Educational Resources Information Center

    Holmes, Bud; Ruiz, Michael J.

    2017-01-01

    Harmonics arise naturally from the resonances in strings and pipes. A video demonstration (Ruiz 2016 "YouTube: Tuba Harmonics" (https://youtu.be/souhEzOP9c4)) is provided where a tubist (coauthor Holmes) produces a phenomenal 24 harmonics using a single tuba pipe length by controlling the buzz of his lips. The frequencies of the…

  10. Clinical Trials

    MedlinePlus

    ... Sponsors Why Are They Important How Do They Work Who Can Participate What To Expect During Benefits and Risks How They Protect Participants Finding Clinical Trials Links Children & Clinical Studies NHLBI Trials Clinical Trial Websites What Are Clinical ...

  11. Twenty-four tuba harmonics using a single pipe length

    NASA Astrophysics Data System (ADS)

    Holmes, Bud; Ruiz, Michael J.

    2017-03-01

    Harmonics arise naturally from the resonances in strings and pipes. A video demonstration (Ruiz 2016 YouTube: Tuba Harmonics (https://youtu.be/souhEzOP9c4)) is provided where a tubist (coauthor Holmes) produces a phenomenal 24 harmonics using a single tuba pipe length by controlling the buzz of his lips. The frequencies of the harmonics, measured with the free software program Audacity, fall excellently on a linear fit using a spreadsheet. The skillful musical production of so many harmonics with a fixed pipe length is an extraordinary illustration of physics.

  12. Harmonic generation by circularly polarized laser beams propagating in plasma

    SciTech Connect

    Agrawal, Ekta; Hemlata,; Jha, Pallavi

    2015-04-15

    An analytical theory is developed for studying the phenomenon of generation of harmonics by the propagation of an obliquely incident, circularly polarized laser beam in homogeneous, underdense plasma. The amplitudes of second and third harmonic radiation as well as detuning distance have been obtained and their variation with the angle of incidence is analyzed. The amplitude of harmonic radiation increases with the angle of incidence while the detuning distance decreases, for a given plasma electron density. It is observed that the generated second and third harmonic radiation is linearly and elliptically polarized, respectively. The harmonic radiation vanishes at normal incidence of the circularly polarized laser beam.

  13. Third Harmonic Mechanism in Complex Plasmonic Fano Structures.

    PubMed

    Metzger, Bernd; Schumacher, Thorsten; Hentschel, Mario; Lippitz, Markus; Giessen, Harald

    2014-06-18

    We perform third harmonic spectroscopy of dolmen-type nanostructures, which exhibit plasmonic Fano resonances in the near-infrared. Strong third harmonic emission is predominantly radiated close to the low energy peak of the Fano resonance. Furthermore, we find that the third harmonic polarization of the subradiant mode interferes destructively and diminishes the nonlinear signal in the far-field. By comparing the experimental third harmonic spectra with finite element simulations and an anharmonic oscillator model, we find strong indications that the source of the third harmonic is the optical nonlinearity of the bare gold enhanced by the resonant plasmonic polarization.

  14. [Practical skills of harmonic scalpel in laparoscopic gastrointestinal surgery].

    PubMed

    Li, Guo-xin

    2013-10-01

    Harmonic scalpel, one of the most commonly used energy tools, have been recognized as an important revolutionary development in surgical device. Due to its convenience in cutting, coagulating, and dissecting harmonic scalpel has been increasingly used to performed surgery by more and more surgeons. In gastrointestinal surgeries, however, many manipulationssuch as dissecting soft connective tissues off the stomach or colon, isolating and cutting particular vessels, would require proper techniques in handling harmonic scalpels. Thus, based on our experiences of using harmonic scalpel in laparoscopic gastrointestinal surgeries, we summarized a "nine-word tactics", which may be helpful for beginners to use harmonic scalpels in a proper and efficient manner.

  15. Harmonized Medical Device Regulation: Need, Challenges, and Risks of not Harmonizing the Regulation in Asia.

    PubMed

    Kaushik, A; Saini, Ks; Anil, B; Rambabu, S

    2010-01-01

    Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well.

  16. Harmonized Medical Device Regulation: Need, Challenges, and Risks of not Harmonizing the Regulation in Asia

    PubMed Central

    Kaushik, A; Saini, KS; Anil, B; Rambabu, S

    2010-01-01

    Medical device sector is one of the most complex and challenging business segments of the healthcare industry with close collaboration between science and engineering. Despite the fact that Asia has 60% of the world population providing large market potential, Asian healthcare expenditure constitutes only 15% of the global healthcare expenditure. The accelerated ageing population and increasing prevalence of chronic disease are the key drivers that contribute toward the increase in the total healthcare expenditure on medical devices in the region. Several policies clearly showed the eagerness of the government to provide better healthcare infrastructure with better medical devices and facilities. The fundamental objective of the regulatory harmonization is to improve the efficiency of national economies and their ability to adopt to change and remain competitive. After the era of liberalization and globalization, the desires of developing economies is to ensure safety and performance of the product brought to their markets and for this harmonized regulation is an important tool for strengthening the same. If we talk about the industry need, then this approach will eliminate redundant requirements that do not contribute to safety and effectiveness. In addition, Asia is diverse in many respects and with it come the various challenges to harmonizing the regulation which includes diversity in culture, politics, economy, historical issues, etc. If, by any reason, the regulation of medical devices is not harmonized and consequently, the harmonized regulation is not adopted, then it leads to serious concerns like delayed or absent access to innovative technology, continued rise in the cost of medical therapies, etc. So this issue is written to attract all stakeholders to move toward the concept of harmonization, keeping in mind their need, challenges, and risks of not harmonizing the regulation as well. PMID:21331201

  17. Harmonics in a Wind Power Plant: Preprint

    SciTech Connect

    Preciado, V.; Madrigal, M.; Muljadi, E.; Gevorgian, V.

    2015-04-02

    Wind power generation has been growing at a very fast pace for the past decade, and its influence and impact on the electric power grid is significant. As in a conventional power plant, a wind power plant (WPP) must ensure that the quality of the power being delivered to the grid is excellent. At the same time, the wind turbine should be able to operate immune to small disturbances coming from the grid. Harmonics are one of the more common power quality issues presented by large WPPs because of the high switching frequency of the power converters and the possible nonlinear behavior from electric machines (generator, transformer, reactors) within a power plant. This paper presents a summary of the most important issues related to harmonics in WPPs and discusses practical experiences with actual Type 1 and Type 3 wind turbines in two WPPs.

  18. A starting earthquake with harmonic effects

    NASA Astrophysics Data System (ADS)

    Babeshko, V. A.; Evdokimova, O. V.; Babeshko, O. M.

    2016-11-01

    The possibility of the occurrence of a starting earthquake with harmonic vibrations (caused by the vertical harmonic effect) of the lithospheric plates and the base on which the plates are resting is considered. This case differs from the static one [1], for which the boundary problem operator is characterized by the presence of manifold eigenvalues. In the dynamic case, the eigenvalues of the operator are single. It is found that the starting earthquake also occurs in this case and, in addition, earthquake hazard can increase due to the appearance of fatigue breakdown conditions in the zone of the approach of lithospheric plates. In turn, fatigue breakdown is related to periodic changes in the effective directions of maximal stresses in this zone.

  19. Spherical harmonics and integration in superspace

    NASA Astrophysics Data System (ADS)

    DeBie, H.; Sommen, F.

    2007-06-01

    In this paper, the classical theory of spherical harmonics in {\\bb R}^m is extended to superspace using techniques from Clifford analysis. After defining a super-Laplace operator and studying some basic properties of polynomial null-solutions of this operator, a new type of integration over the supersphere is introduced by exploiting the formal equivalence with an old result of Pizzetti. This integral is then used to prove orthogonality of spherical harmonics of different degree, Green-like theorems and also an extension of the important Funk-Hecke theorem to superspace. Finally, this integration over the supersphere is used to define an integral over the whole superspace, and it is proven that this is equivalent with the Berezin integral, thus providing a more sound definition of the Berezin integral.

  20. Super/subradiant second harmonic generation

    NASA Astrophysics Data System (ADS)

    Koganov, Gennady A.; Shuker, Reuben

    2017-04-01

    A scheme for active second harmonics generation is suggested. The system comprises N three-level atoms in ladder configuration, situated into a resonant cavity. The system generates the field whose frequency is twice the frequency of the pumping laser, and the field phase is locked to the phase of the pumping field. It is found that the system can lase in either superradiant or subradiant regime, depending on the number of atoms N. When N passes some critical value the transition from the super to subradiance occurs in a phase-transition-like manner. Stability study of the steady state supports this conclusion. For experimental realization of the super/subradiant second harmonics generation we propose semiconductor quantum well structures, superconducting quantum circuits, and evanescently coupled waveguides in which equally spaced levels relevant to this study exist.

  1. Prolate spheroidal harmonic expansion of gravitational field

    SciTech Connect

    Fukushima, Toshio

    2014-06-01

    As a modification of the oblate spheroidal case, a recursive method is developed to compute the point value and a few low-order derivatives of the prolate spheroidal harmonics of the second kind, Q{sub nm} (y), namely the unnormalized associated Legendre function (ALF) of the second kind with its argument in the domain, 1 < y < ∞. They are required in evaluating the prolate spheroidal harmonic expansion of the gravitational field in addition to the point value and the low-order derivatives of P-bar {sub nm}(t), the 4π fully normalized ALF of the first kind with its argument in the domain, |t| ≤ 1. The new method will be useful in the gravitational field computation of elongated celestial objects.

  2. Coulomb time delays in high harmonic generation

    NASA Astrophysics Data System (ADS)

    Torlina, Lisa; Smirnova, Olga

    2017-02-01

    Measuring the time it takes to remove an electron from an atom or molecule during photoionization has been the focus of a number of recent experiments using newly developed attosecond spectroscopies. The interpretation of such measurements, however, depends critically on the measurement protocol and the specific observables available in each experiment. One such protocol relies on high harmonic generation. In this paper, we derive rigorous and general expressions for ionisation and recombination times in high harmonic generation experiments. We show that these times are different from, but related to, ionisation times measured in photoelectron spectroscopy: that is, those obtained using the attosecond streak camera, RABBITT and attoclock methods. We then proceed to use the analytical R-matrix theory to calculate these times and compare them with experimental values.

  3. Second Harmonic Imaging of Membrane Potential.

    PubMed

    Loew, Leslie M; Lewis, Aaron

    2015-01-01

    The non-linear optical effect known as second harmonic generation (SHG) has been recognized since the earliest days of the laser. But it has only been in the last 20 years that it has begun to emerge as a viable microscope imaging contrast mechanism for visualization of cell and tissue structure and function. This is because only small modifications are required to equip a standard laser scanning 2-photon microscope for second harmonic imaging microscopy (SHIM). SHG signals from certain membrane-bound dyes are highly sensitive to membrane potential, indicating that SHIM may become a valuable probe of cell physiology. However, for the current generation of dyes and microscopes, the small signal size limits the number of photons that can be collected during the course of a fast action potential. Better dyes and optimized microscope optics could ultimately lead to the ability to image neuronal electrical activity with SHIM.

  4. Second harmonic generation and sum frequency generation

    SciTech Connect

    Pellin, M.J.; Biwer, B.M.; Schauer, M.W.; Frye, J.M.; Gruen, D.M.

    1990-01-01

    Second harmonic generation and sum frequency generation are increasingly being used as in situ surface probes. These techniques are coherent and inherently surface sensitive by the nature of the mediums response to intense laser light. Here we will review these two techniques using aqueous corrosion as an example problem. Aqueous corrosion of technologically important materials such as Fe, Ni and Cr proceeds from a reduced metal surface with layer by layer growth of oxide films mitigated by compositional changes in the chemical makeup of the growing film. Passivation of the metal surface is achieved after growth of only a few tens of atomic layers of metal oxide. Surface Second Harmonic Generation and a related nonlinear laser technique, Sum Frequency Generation have demonstrated an ability to probe the surface composition of growing films even in the presence of aqueous solutions. 96 refs., 4 figs.

  5. High-order harmonic generation in alkanes

    SciTech Connect

    Altucci, C.; Velotta, R.; Heesel, E.; Springate, E.; Marangos, J. P.; Vozzi, C.; Benedetti, E.; Calegari, F.; Sansone, G.; Stagira, S.; Nisoli, M.; Tosa, V.

    2006-04-15

    We have investigated the process of high-order harmonic generation in light alkanes by using femtosecond laser pulses. We show the experimental results cannot be matched by a model that assumes a single active electron only in a hydrogenic s orbital. Clear evidences are shown of the important role played by the p-like character originating from the covalent C-H bond. By constructing a suitable mixture of s-type and p-type atomic wave functions, an excellent agreement between measurements in methane and simulations is found, thus confirming the validity of the developed method as a general tool for the analysis of high-order harmonic generation in complex molecules.

  6. Harmonic cavities for the NLC damping rings

    SciTech Connect

    de Santis, S.; Wolski, A.

    2003-05-29

    To achieve high luminosity, a linear collider needs damping rings to produce beams with very small transverse emittances. In the NLC, design constraints place the Main Damping Rings in a parameter regime where intrabeam scattering (IBS) is likely to be a limitation on the emittance, and hence on the final luminosity. It is possible to mitigate the effects of IBS by lengthening the bunch: this may be achieved by redesigning the lattice with higher momentum compaction, or by use of higher harmonic cavities. Here, we consider the latter approach. We estimate the required bunch lengthening that might be needed, outline some appropriate parameters for the harmonic cavities, and discuss some of the effects that might be introduced or exacerbated by the cavities, such as synchronous phase variation along the bunch train.

  7. Fast interferometric second harmonic generation microscopy

    PubMed Central

    Bancelin, Stéphane; Couture, Charles-André; Légaré, Katherine; Pinsard, Maxime; Rivard, Maxime; Brown, Cameron; Légaré, François

    2016-01-01

    We report the implementation of fast Interferometric Second Harmonic Generation (I-SHG) microscopy to study the polarity of non-centrosymmetric structures in biological tissues. Using a sample quartz plate, we calibrate the spatially varying phase shift introduced by the laser scanning system. Compensating this phase shift allows us to retrieve the correct phase distribution in periodically poled lithium niobate, used as a model sample. Finally, we used fast interferometric second harmonic generation microscopy to acquire phase images in tendon. Our results show that the method exposed here, using a laser scanning system, allows to recover the polarity of collagen fibrils, similarly to standard I-SHG (using a sample scanning system), but with an imaging time about 40 times shorter. PMID:26977349

  8. Power System Harmonic Elimination to Improve Power Quality

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, K.; Ramachandaramurthy, V. K.

    2015-06-01

    An improvised RLC interface filter for a Dynamic Voltage Restorer (DVR) is proposed. The RLC filter is connected in the front end between the IGBT based Voltage Source Inverter (VSI) and the injection transformer and is able to eliminate voltage harmonics in the system and also switching harmonics generated from VSI. The voltage at the sensitive load end is pure sinusoidal. In this method, the DVR produced Pulse Width Modulation (PWM) voltage with voltage harmonic canceling the voltage harmonic generated from the supply main. The VSI handles harmonic power. The low order switching harmonics generated by the IGBT based VSI is suppressed. The DVR has greater voltage injection capability. Good dynamic and transient results recorded and Total Harmonic Distortion (THD) at the sensitive load end is minimized. The voltage at the sensitive load is sinusoidal and at 1.0 pu. PSCAD/EMTDC is used to validate the performance of the interface filter and the DVR. Simulated results are presented.

  9. Localized waves with spherical harmonic symmetries

    NASA Astrophysics Data System (ADS)

    Mills, M. S.; Siviloglou, G. A.; Efremidis, N.; Graf, T.; Wright, E. M.; Moloney, J. V.; Christodoulides, D. N.

    2012-12-01

    We introduce a class of propagation invariant spatiotemporal optical wave packets with spherical harmonic symmetries in their field configurations. The evolution of these light orbitals is considered theoretically in anomalously dispersive media, and their spinning dynamics are analyzed in terms of their corresponding energy flows. Similarly, localized waves generated via spherical superposition from Archimedean and Platonic solids in k⃗-ω space are investigated in this work.

  10. Comments on the Method of harmonic balance

    NASA Technical Reports Server (NTRS)

    Mickens, R. E.

    1984-01-01

    The advantages and limitations of the harmonic-balance or describing-function approximation scheme for solving nonlinear ordinary differential equations of oscillatory motion are discussed. Advantages include appicability to equations of any order and with large degrees of nonlinearity, ease of determining limit-cycle behavior and its stability, and overall speed and efficiency; the limitation rules are essentially those described by Mickens (1983). It is pointed out that perturbation procedures provide better results when the degree of nonlinearity is small.

  11. Towards harmonization: the European biotechnology patent directive.

    PubMed

    Curley, Duncan

    2002-01-01

    Having first been proposed over a decade ago to harmonize European patent law for the benefit of Europe's fledgling biotechnology industry, the Biotechnology Patent Directive underwent a somewhat tortured introduction to adolescence when its adoption was challenged by a legal annulment action from the Governments of the Netherlands, Italy and Norway. This article explores the nature of the legal challenge to the Directive, which to an extent typify European concerns about biotechnological inventions, particularly the "patenting of life."

  12. Interpolating Spherical Harmonics for Computing Antenna Patterns

    DTIC Science & Technology

    2011-07-01

    and Antenna Patterns 1 2 Short-Wire Antennas 3 3 Spherical Harmonic Expansions 10 4 Adaptive Spline Interpolation ( ASI ) 14 5 Testing the ASI Algorithm...frequency band is possible. This report offers a simple adaptive spline interpolation ( ASI ) algorithm to benchmark more sophisticated pattern...θ, φ) and their expansions. Sec- tion 4 uses one of the antenna patterns to develop the ASI algorithm and the error bounds. Section 5 tests the ASI

  13. High Harmonic Generation at Long Wavelengths

    SciTech Connect

    Sheehy, B.; Martin, J. D. D.; DiMauro, L. F.; Agostini, P.; Schafer, K. J.; Gaarde, M. B.; Kulander, K. C.

    1999-12-20

    High harmonic radiation spectra up to 19th order in alkali metal vapors excited by an intense, picosecond mid-infrared (3-4 {mu} m ) laser are reported and compared to theory. The strong-field dynamics in the alkali metal atoms exhibit significant differences from all previously studied systems due to the strong coupling between their ground and first excited states. (c) 1999 The American Physical Society.

  14. Two atoms in an anisotropic harmonic trap

    SciTech Connect

    Idziaszek, Z.; Calarco, T.

    2005-05-15

    We consider the system of two interacting atoms confined in axially symmetric harmonic trap. Within the pseudopotential approximation, we solve the Schroedinger equation exactly, discussing the limits of quasi-one-and quasi-two-dimensional geometries. Finally, we discuss the application of an energy-dependent pseudopotential, which allows us to extend the validity of our results to the case of tight traps and large scattering lengths.

  15. A call for collaborative semantics harmonization.

    PubMed

    Weng, Chunhua; Fridsma, Douglas B

    2006-01-01

    Semantic interoperability problems occur when shared vocabularies are used for inconsistent meanings in varied contexts among distributed and heterogeneous healthcare information systems. Methods such as XML only work at the syntax level and do not deal with semantics. We are missing the tools that support consensus semantics modeling across multidisciplinary healthcare communities. Here we briefly define what collaborative semantic harmonization is and describe an early design to achieve it.

  16. Maximizing your Process Improvement ROI through Harmonization

    DTIC Science & Technology

    2008-03-01

    ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Carnegie...Mellon University ,Software Engineering Institute (SEI),Pittsburgh,PA,15213 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY...process improvement approaches such organizations need to consider: The 1 st white paper addresses the benefits of a harmonized approach when

  17. Critical slowing down with bistable higher harmonics

    NASA Astrophysics Data System (ADS)

    Sharaby, Yasser A.; Hassan, S. S.; Joshi, A.

    2013-01-01

    Switching response in an optical bistable model of two-level atoms in a ring cavity is investigated outside the rotating wave approximation (RWA) in the high- and low-Q cavity cases. Analytical and numerical investigations of the non-autonomous model Bloch equations, up to first Fourier harmonics, show that the switching time in response to linear perturbation of the incident field at the critical points of the bistable curves is significantly affected by the atomic and cavity detuning parameters. The faster oscillatory behavior outside the RWA reflects itself in the additional ultra-low output (first harmonic) field component, which has reversed bistable feature in both the high-Q and low-Q cases. Irregular oscillations with increased atomic detuning are showed only in the lower bistable branch of the first harmonic field. Irregularity of the oscillations is due to the interference of the oscillations of the higher frequency terms with the atomic dispersive polarization in the high-Q case, and the Rabi oscillations in the low-Q case.

  18. Dark-matter harmonics beyond annual modulation

    SciTech Connect

    Lee, Samuel K.; Lisanti, Mariangela; Safdi, Benjamin R. E-mail: mlisanti@princeton.edu

    2013-11-01

    The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic spectrum. Consequently, the higher-order harmonic modes are a powerful tool for identifying a potential signal from interactions with the Galactic dark-matter halo.

  19. Enhanced dynamical stability with harmonic slip stacking

    DOE PAGES

    Eldred, Jeffrey; Zwaska, Robert

    2016-10-26

    We develop a configuration of radio-frequency (rf) cavities to dramatically improve the performance of slip-stacking. Slip-stacking is an accumulation technique used at Fermilab to nearly double proton intensity by maintaining two beams of different momenta in the same storage ring. The two particle beams are longitudinally focused in the Recycler by two 53 MHz 100 kV rf cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV rf cavity with a frequency at the double the average of the upper and lower main rf frequencies. We show the harmonic rf cavity cancels out themore » resonances generated between the two main rf cavities and we derive the relationship between the harmonic rf voltage and the main rf voltage. We find the area factors that can be used to calculate the available phase space area for any set of beam parameters without individual simulation. We establish Booster beam quality requirements to achieve 99\\% slip-stacking efficiency. We measure the longitudinal distribution of the Booster beam and use it to generate a realistic beam model for slip-stacking simulation. In conclusion, we demonstrate that the harmonic rf cavity can not only reduce particle loss during slip-stacking, but also reduce the final longitudinal emittance.« less

  20. Harmonics of circadian gene transcription in mammals.

    PubMed

    Hughes, Michael E; DiTacchio, Luciano; Hayes, Kevin R; Vollmers, Christopher; Pulivarthy, S; Baggs, Julie E; Panda, Satchidananda; Hogenesch, John B

    2009-04-01

    The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.

  1. Harmonics of Circadian Gene Transcription in Mammals

    PubMed Central

    Hayes, Kevin R.; Vollmers, Christopher; Pulivarthy, S.; Baggs, Julie E.; Panda, Satchidananda; Hogenesch, John B.

    2009-01-01

    The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse. PMID:19343201

  2. The polarization of second harmonic plasma emission

    NASA Technical Reports Server (NTRS)

    Melrose, D. B.; Dulk, G. A.; Smerd, S. F.

    1978-01-01

    It is shown that second-harmonic plasma emission is partially polarized in the sense of the ordinary mode of magnetoionic theory only when the Langmuir waves are confined to a small range of angles (less than 30 deg) to the magnetic-field lines. Consequently, Suzuki and Sheridan's (1977) observations of the polarization of harmonic Type III emission implies that (at least in the cases reported) the Langmuir waves must be nearly one-dimensional. For a nearly one-dimensional distribution, the degree of polarization and the frequency of observation should be related to the magnetic field. For the observed polarization of Type III bursts, the implied magnetic-field strengths are strong enough for induced scattering to cause the Langmuir waves to become nearly one-dimensional, which is consistent with the observed sense of polarization. In other applications of harmonic plasma emission where the Langmuir waves might be isotropic or in a loss-cone distribution, polarization in the sense of the extraordinary mode is predicted.

  3. Enhanced dynamical stability with harmonic slip stacking

    NASA Astrophysics Data System (ADS)

    Eldred, Jeffrey; Zwaska, Robert

    2016-10-01

    We develop a configuration of radio-frequency (rf) cavities to dramatically improve the performance of slip stacking. Slip stacking is an accumulation technique used at Fermilab to nearly double proton intensity by maintaining two beams of different momenta in the same storage ring. The two particle beams are longitudinally focused in the Recycler by two 53 MHz 100 kV rf cavities with a small frequency difference between them. We propose an additional 106 MHz 20 kV rf cavity with a frequency at the double the average of the upper and lower main rf frequencies. We show the harmonic rf cavity cancels out the resonances generated between the two main rf cavities and we derive the relationship between the harmonic rf voltage and the main rf voltage. We find the area factors that can be used to calculate the available phase space area for any set of beam parameters without individual simulation. We establish Booster beam quality requirements to achieve 99% slip stacking efficiency. We measure the longitudinal distribution of the Booster beam and use it to generate a realistic beam model for slip stacking simulation. We demonstrate that the harmonic rf cavity can not only reduce particle loss during slip stacking, but also reduce the final longitudinal emittance.

  4. Ultrafast Plasmonic Control of Second Harmonic Generation

    DOE PAGES

    Davidson, Roderick B.; Yanchenko, Anna; Ziegler, Jed I.; ...

    2016-06-01

    Efficient frequency conversion techniques are crucial to the development of plasmonic metasurfaces for information processing and signal modulation. In principle, nanoscale electric-field confinement in nonlinear materials enables higher harmonic conversion efficiencies per unit volume than those attainable in bulk materials. Here we demonstrate efficient second-harmonic generation (SHG) in a serrated nanogap plasmonic geometry that generates steep electric field gradients on a dielectric metasurface. An ultrafast control pulse is used to control plasmon-induced electric fields in a thin-film material with inversion symmetry that, without plasmonic enhancement, does not exhibit an even-order nonlinear optical response. The temporal evolution of the plasmonic near-fieldmore » is characterized with ~100 as resolution using a novel nonlinear interferometric technique. The serrated nanogap is a unique platform in which to investigate optically controlled, plasmonically enhanced harmonic generation in dielectric materials on an ultrafast time scale. Lastly, this metamaterial geometry can also be readily extended to all-optical control of other nonlinear phenomena, such as four-wave mixing and sum- and difference-frequency generation, in a wide variety of dielectric materials.« less

  5. Ultrafast Plasmonic Control of Second Harmonic Generation

    SciTech Connect

    Davidson, Roderick B.; Yanchenko, Anna; Ziegler, Jed I.; Avanesyan, Sergey M.; Lawrie, Benjamin J.; Haglund, Richard F.

    2016-06-01

    Efficient frequency conversion techniques are crucial to the development of plasmonic metasurfaces for information processing and signal modulation. In principle, nanoscale electric-field confinement in nonlinear materials enables higher harmonic conversion efficiencies per unit volume than those attainable in bulk materials. Here we demonstrate efficient second-harmonic generation (SHG) in a serrated nanogap plasmonic geometry that generates steep electric field gradients on a dielectric metasurface. An ultrafast control pulse is used to control plasmon-induced electric fields in a thin-film material with inversion symmetry that, without plasmonic enhancement, does not exhibit an even-order nonlinear optical response. The temporal evolution of the plasmonic near-field is characterized with ~100 as resolution using a novel nonlinear interferometric technique. The serrated nanogap is a unique platform in which to investigate optically controlled, plasmonically enhanced harmonic generation in dielectric materials on an ultrafast time scale. Lastly, this metamaterial geometry can also be readily extended to all-optical control of other nonlinear phenomena, such as four-wave mixing and sum- and difference-frequency generation, in a wide variety of dielectric materials.

  6. Bounce harmonic Landau damping of plasma waves

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Kabantsev, A. A.; Dubin, D. H. E.; Ashourvan, A.; Driscoll, C. F.

    2016-05-01

    We present measurements of bounce harmonic Landau damping due to z-variations in the plasma potential, created by an azimuthally symmetric "squeeze" voltage Vs applied to the cylindrical wall. Traditional Landau damping on spatially uniform plasma is weak in regimes where the wave phase velocity vp h≡ω/k is large compared to the thermal velocity. However, z-variations in plasma density and potential create higher spatial harmonics, which enable resonant wave damping by particles with bounce-averaged velocities vp h/n , where n is an integer. In our geometry, the applied squeeze predominantly generates a resonance at vp h/3 . Wave-coherent laser induced fluorescence measurements of particle velocities show a distinctive Landau damping signature at vp h/3 , with amplitude proportional to the applied Vs. The measured (small amplitude) wave damping is then proportional to Vs2 , in quantitative agreement with theory over a range of 20 in temperature. Significant questions remain regarding "background" bounce harmonic damping due to ubiquitous confinement fields and regarding the saturation of this damping at large wave amplitudes.

  7. Food legislation and its harmonization in Russia.

    PubMed

    Shamtsyan, Mark

    2014-08-01

    Bringing Russian legislation into compliance with international norms and standards is necessary after its accession to the World Trade Organization. Harmonization of food legislation and of sanitary and phytosanitary measures are among the problems that had to be solved first. Many Russian food and trade regulations had been changed or are still in the process of being reformed, largely owing to a policy of integration pursued by the Customs Union of Russia, Belarus and Kazakhstan. However, as a member of the Eurasian Economic Community, Russia is also engaged not only in harmonization throughout the Customs Union but also Kirgizstan and Tajikistan, and Armenia, Moldova and Ukraine as observer countries. Russia also continues to coordinate policy reforms closely with the European Union, its primary trade partner, ultimately bringing Russian food and sanitary norms closer to international standards (e.g. Codex). Today, all participants in the Russian food production chain, processing and sale of foods have to deal with growing numbers of security standards. Many organizations are certified under several schemes, which leads to unnecessary costs. Harmonization of standards has helped promote solutions in the domestic market as well as import-export of foods and raw materials for production. Priorities have included food safety for human health, consumer protection, removal of hazardous and/or adulterated products and increased competition within the domestic food market as well as mutual recognition of certification in bilateral and multilateral (inter)national agreements. © 2013 Society of Chemical Industry.

  8. A method for suppression of spurious fundamental-harmonic waves in gyrotrons operating at the second cyclotron harmonic

    SciTech Connect

    Kalynov, Yu. K.; Osharin, I. V.; Savilov, A. V.

    2016-05-15

    A typical problem of gyrotrons operating at high harmonics of the electron cyclotron frequency is the suppression of parasitic near-cutoff waves excited at lower harmonics. In this paper, a method for a significant improvement of the selectivity of the second-harmonic gyrotrons is proposed. This method is based on the use of quasi-regular cavities with short irregularities, which provide different effects on the process of excitation of the operating second-harmonic wave and the spurious fundamental-harmonic wave by the electron beam.

  9. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    SciTech Connect

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  10. Harmonic Scalpel versus Electrocautery Dissection in Modified Radical Mastectomy for Breast Cancer: A Meta-Analysis

    PubMed Central

    Huang, Jinbo; Yu, Yinghua; Wei, Changyuan; Qin, Qinghong; Mo, Qinguo; Yang, Weiping

    2015-01-01

    Background Despite the common use of conventional electrocautery in modified radical mastectomy for breast cancer, the harmonic scalpel is recently emerging as a dominant surgical instrument for dissection and haemostasis, which is thought to reduce the morbidity, such as seroma and blood loss. But the results of published trials are inconsistent. So we made the meta-analysis to assess the intraoperative and postoperative endpoints among women undergoing modified radical mastectomy with harmonic scalpel or electrocautery. Methods A comprehensive literature search of case-control studies from PubMed, MEDLINE, EMBASE and Cochrane Library databases involving modified radical mastectomy with harmonic scalpel or electrocautery was performed. We carried out a meta-analysis of primary endpoints including postoperative drainage, seroma development, intraoperative blood loss and secondly endpoints including operative time and wound complications. We used odds ratios (ORs) with 95% confidence intervals (CIs) to evaluate the effect size for categorical outcomes and standardised mean differences (SMDs) for continuous outcomes. Results A total of 11 studies with 702 patients were included for this meta-analysis. There was significant difference in total postoperative drainage (SMD: -0.74 [95%CI: -1.31, -0.16]; P< 0.01), seroma development[OR: 0.49 (0.34, 0.70); P < 0.01], intraoperative blood loss(SMD: -1.14 [95%CI: -1.81,-0.47]; P < 0.01) and wound complications [OR: 0.38 (0.24, 0.59); P < 0.01] between harmonic scalpel dissection and standard electrocautery in modified radical mastectomy for breast cancer. No difference was found as for operative time between harmonic scalpel dissection and standard electrocautery (SMD: 0.04 [95%CI: -0.41, 0.50]; P = 0.85). Conclusion Compared to standard electrocautery, harmonic scalpel dissection presents significant advantages in decreasing postoperative drainage, seroma development, intraoperative blood loss and wound complications in

  11. Harmonic Scalpel versus Electrocautery Dissection in Modified Radical Mastectomy for Breast Cancer: A Meta-Analysis.

    PubMed

    Huang, Jinbo; Yu, Yinghua; Wei, Changyuan; Qin, Qinghong; Mo, Qinguo; Yang, Weiping

    2015-01-01

    Despite the common use of conventional electrocautery in modified radical mastectomy for breast cancer, the harmonic scalpel is recently emerging as a dominant surgical instrument for dissection and haemostasis, which is thought to reduce the morbidity, such as seroma and blood loss. But the results of published trials are inconsistent. So we made the meta-analysis to assess the intraoperative and postoperative endpoints among women undergoing modified radical mastectomy with harmonic scalpel or electrocautery. A comprehensive literature search of case-control studies from PubMed, MEDLINE, EMBASE and Cochrane Library databases involving modified radical mastectomy with harmonic scalpel or electrocautery was performed. We carried out a meta-analysis of primary endpoints including postoperative drainage, seroma development, intraoperative blood loss and secondly endpoints including operative time and wound complications. We used odds ratios (ORs) with 95% confidence intervals (CIs) to evaluate the effect size for categorical outcomes and standardised mean differences (SMDs) for continuous outcomes. A total of 11 studies with 702 patients were included for this meta-analysis. There was significant difference in total postoperative drainage (SMD: -0.74 [95%CI: -1.31, -0.16]; P< 0.01), seroma development[OR: 0.49 (0.34, 0.70); P < 0.01], intraoperative blood loss(SMD: -1.14 [95%CI: -1.81,-0.47]; P < 0.01) and wound complications [OR: 0.38 (0.24, 0.59); P < 0.01] between harmonic scalpel dissection and standard electrocautery in modified radical mastectomy for breast cancer. No difference was found as for operative time between harmonic scalpel dissection and standard electrocautery (SMD: 0.04 [95%CI: -0.41, 0.50]; P = 0.85). Compared to standard electrocautery, harmonic scalpel dissection presents significant advantages in decreasing postoperative drainage, seroma development, intraoperative blood loss and wound complications in modified radical mastectomy for breast

  12. Axial resolution enhancement of third harmonic generation microscopy by harmonic focal point axial modulation

    NASA Astrophysics Data System (ADS)

    Mozdoor Dashtabi, Mahdi; Arabanian, Atoosa Sadat; Massudi, Reza

    2017-02-01

    Harmonic focal point axial modulation (h-FPAM) in nonlinear optical microscopy is introduced and used to enhance the axial resolution and the signal to background ratio by modulating the focal point of a beam of femtosecond pulses train along the axial direction and phase sensitively filtering the resulting signals using a lock-in amplifier. Axial resolution enhancement factor of 2.05 is acquired in 2f detection mode for the third harmonic generation microscopy of glass-oil interfaces. This technique also resolves the image interpretation problem of the fundamental harmonic FPAM technique. Moreover, the potential of this technique for axial sectioning is demonstrated by acquiring images from a red blood cell.

  13. Imaging parameters on third harmonic transmit phasing for tissue harmonic generation.

    PubMed

    Shen, Che-Chou; Wang, Yu-Chun; Yeh, Chih-Kuang

    2008-06-01

    In third harmonic (3f0) transmit phasing, transmit waveforms comprising fundamental (f0) signal and 3f0 signal are used to generate both frequency-sum and frequency-difference components for manipulation of tissue harmonic amplitude. Nevertheless, the acoustic propagation of 3f0 transmit signal suffers from more severe attenuation and phase aberration than the f0 signal and hence degrades the performance of 3f0 transmit phasing. Besides, 3f0 transmit parameters such as aperture size and signal bandwidth are also influential in 3f0 transmit phasing. In this study, extensive simulations were performed to investigate the effects of these imaging parameters. Results indicate that the harmonic enhancement and suppression in 3f0 transmit phasing are compromised when the magnitude of frequency-difference component decreases in the presence of tissue attenuation and phase aberration. To compensate for the reduced frequency-difference component, a higher 3f0 transmit amplitude can be used. When the transmit parameters are concerned, a smaller 3f0 transmit aperture can provide more axially uniform harmonic enhancement and more effective suppression of harmonic amplitude. In addition, the spectral leakage signal also interferes with tissue harmonics and degrades the efficacy of 3f0 transmit phasing. Our results suggest that, in the method of 3f0 transmit phasing, the transmit amplitude, phase and aperture size of 3f0 signal should remain adjustable for optimization of clinical performance. Besides, multipulse sequences such as pulse inversion are also favorable for leakage removal in 3f0 transmit phasing.

  14. The sheath effect on the floating harmonic method

    SciTech Connect

    Lee, Jaewon; Kim, Kyung-Hyun; Chung, Chin-Wook

    2015-12-15

    The floating harmonic method biases sinusoidal voltage to a probe sheath, and as its response, harmonic currents can be obtained. These currents can be used to determine the plasma parameters. However, different shapes of probes have different shapes of sheaths that can affect the diagnostic results. However, no research has been done on the sheath effect on the floating harmonic method. Therefore, we investigate the effect of the sheath during floating harmonic diagnostics by comparing cylindrical and planar probes. While the sinusoidal voltages were applied to a probe, because the sheath oscillated, the time variant ion current and their harmonic currents were added to the electron harmonic currents. In the floating harmonic method, the harmonic currents are composed of only the electron harmonic currents. Therefore, the ion harmonic currents affect the diagnostic results. In particular, the electron temperature obtained by the small probe tip was higher than that of the large probe tip. This effect was exacerbated when the ratio of the probe tip radius to the sheath length was smaller.

  15. Toward Rigorous Data Harmonization in Cancer Epidemiology Research: One Approach.

    PubMed

    Rolland, Betsy; Reid, Suzanna; Stelling, Deanna; Warnick, Greg; Thornquist, Mark; Feng, Ziding; Potter, John D

    2015-12-15

    Cancer epidemiologists have a long history of combining data sets in pooled analyses, often harmonizing heterogeneous data from multiple studies into 1 large data set. Although there are useful websites on data harmonization with recommendations and support, there is little research on best practices in data harmonization; each project conducts harmonization according to its own internal standards. The field would be greatly served by charting the process of data harmonization to enhance the quality of the harmonized data. Here, we describe the data harmonization process utilized at the Fred Hutchinson Cancer Research Center (Seattle, Washington) by the coordinating centers of several research projects. We describe a 6-step harmonization process, including: 1) identification of questions the harmonized data set is required to answer; 2) identification of high-level data concepts to answer those questions; 3) assessment of data availability for data concepts; 4) development of common data elements for each data concept; 5) mapping and transformation of individual data points to common data elements; and 6) quality-control procedures. Our aim here is not to claim a "correct" way of doing data harmonization but to encourage others to describe their processes in order that we can begin to create rigorous approaches. We also propose a research agenda around this issue. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. Coherent harmonic production using a two-section undulator FEL

    SciTech Connect

    Jaroszynski, D.A.; Prazeres, R.; Glotin, F.

    1995-12-31

    We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.

  17. Active harmonic filter technology and market assessment. Final report

    SciTech Connect

    Bhattacharya, S.; Divan, D.; Sutherland, P.

    1998-08-01

    Non-linear loads such as three-phase rectifiers, adjustable speed drives (ASDs), and arcing loads can cause voltage distortion and other power quality problems due to their interaction with the power grid. This report provides a technical and marketing assessment of active harmonic filters, a promising approach to preventing these problems at their source. Although predicting the direction and magnitude of harmonic currents is difficult due to highly interconnected nature of distribution systems, even small harmonic producing loads can result in high levels of harmonic current flow between the utility and a customer and can also cause a resonance problem at sites far removed from the harmonic producing load. The best way to keep voltage distortion low in a utility system is to constrain the harmonic currents at their sources. However, since regulation of harmonic pollution does not provide any additional value to the customer, it is unlikely that any controls will be implemented on a consistent basis in the absence of mandatory requirements. In the United States, a step toward a standard operating practice is the IEEE 519-1992 recommended harmonic standard that provides guidelines for limiting harmonic currents by industrial plants. This report identifies the equipment likely to produce harmonic loads and explains the kinds of problems that harmonic currents can cause in a utility distribution system. It describes possible solutions to these problems, including harmonic filtering and other technologies. The report examines the prospects for wider use of active harmonic filter technology and discusses the important marketing issues for potential active filter marketers and manufacturers, such as the barriers to and drivers of increased use of active filter technology and the price points for active filters.

  18. Influence of a harmonic in the response on randomdec signature

    NASA Astrophysics Data System (ADS)

    Modak, S. V.

    2011-10-01

    Operational Modal Analysis (OMA) extracts modal parameters of a structure using their output response, during operation in general. OMA, when applied to mechanical engineering structures is often faced with the problem of harmonics present in the output response, and can cause erroneous modal extraction. The random decrement (RD) method of OMA helps extract randomdec signature data that can be further processed to obtain modal parameters of a structure. This paper for the first time analyses influence of a harmonic in the response on randomdec signature. Fundamental equations based on probability are derived for analyzing the influence of a harmonic on randomdec signature. These probabilistic equations are then used to predict the amplitude of the harmonic in randomdec signature. Randomdec signature of a pure harmonic signal is also derived and it is shown that it is of the same frequency as that of the harmonic signal, but has an amplitude equal to the trigger level used to find the randomdec. Based on the developed theory, new insights into the influence of harmonic on randomdec are presented based on an example. It is shown that the influence of the harmonic on randomdec is characterized by the conditional probability density function of the harmonic. It is found that more unsymmetrical is this PDF, more is the amplitude of the harmonic that is present in the randomdec signature. The amplitude of the harmonic in the randomdec is shown to be the conditional expected value of the harmonic. It is also shown that as the random component of the response increases then the amplitude of the harmonic in the randomdec decreases and in the limit can be completely eliminated.

  19. Variational study of a two-level system coupled to a harmonic oscillator in an ultrastrong-coupling regime

    SciTech Connect

    Hwang, Myung-Joong; Choi, Mahn-Soo

    2010-08-15

    The nonclassical behavior of a two-level system coupled to a harmonic oscillator is investigated in the ultrastrong coupling regime. We revisit the variational solution of the ground state and find that the existing solutions do not account accurately for nonclassical effects such as squeezing. We suggest a trial wave function and demonstrate that it has an excellent accuracy for the quantum correlation effects as well as for the energy.

  20. 34 GHz second-harmonic peniotron oscillator

    NASA Astrophysics Data System (ADS)

    Dressman, Lawrence Jude

    Harmonic operation of gyro-devices has been proposed as a way to lower the magnetic field required to a level feasible with normal (i.e., non-superconducting) magnets. The problem is, however, that gyrotron efficiency drops dramatically at harmonics greater than two, making development of such a device of limited utility. A promising solution to this quandary is the development of a related device, the peniotron, which is believed capable of achieving both high efficiency and harmonic operation resulting in a reduction of the required axial magnetic field. Although the physics of the peniotron interaction, including its high electronic conversion efficiency, has been understood and experimentally verified, demonstration of characteristics consistent with a practical device has been more elusive. This is the goal of this effort---specifically, to demonstrate high device efficiency (defined as the actual power output as a fraction of the electron beam power) with an electron beam generated by a compact cusp electron gun consistent in size and performance with other microwave vacuum electron devices. The cavity design process revealed that the pi/2 mode couples easily to the output circular waveguide. In fact, the transition to circular waveguide produced such a low reflection coefficient that an iris was needed at the cavity output to achieve the desired Q. Integral couplers were also designed to couple directly into the slotted cavity for diagnostic purposes for simplicity in this proof-of-principle physics experiment. This eliminated the need for a high-power circular vacuum window and allowed the diagnostic coupling to be made in standard WR-28 rectangular waveguide. Although mode competition did prevent the second-harmonic peniotron mode from being tuned over its entire range of magnetic field, the peniotron mode was stable over a range sufficient to allow useful experimental data to be obtained. However, another unexpected problem which occurred during execution

  1. Harmonic analysis of the precipitation in Greece

    NASA Astrophysics Data System (ADS)

    Nastos, P. T.; Zerefos, C. S.

    2009-04-01

    Greece is a country with a big variety of climates due to its geographical position, to the many mountain ranges and also to the multifarious and long coastline. The mountainous volumes are of such orientation that influences the distribution of the precipitation, having as a result, Western Greece to present great differentiations from Central and Eastern Greece. The application of harmonic analysis to the annual variability of precipitation is the goal of this study, so that the components, which compose the annual variability, be elicited. For this purpose, the mean monthly precipitation data from 30 meteorological stations of National Meteorological Service were used for the time period 1950-2000. The initial target is to reduce the number of variables and to detect structure in the relationships between variables. The most commonly used technique for this purpose is the application of Factor Analysis to a table having as columns the meteorological stations-variables and rows the monthly mean precipitation, so that 2 main factors were calculated, which explain the 98% of total variability of precipitation in Greece. Factor 1, representing the so-called uniform field and interpreting the most of the total variance, refers in fact to the Mediterranean depressions, affecting mainly the West of Greece and also the East Aegean and the Asia Minor coasts. In the process, the Fourier Analysis was applied to the factor scores extracted from the Factor Analysis, so that 2 harmonic components are resulted, which explain above the 98% of the total variability of each main factor, and are due to different synoptic and thermodynamic processes associated with Greece's precipitation construction. Finally, the calculation of the time of occurrence of the maximum precipitation, for each harmonic component of each one of the two main factors, gives the spatial distribution of appearance of the maximum precipitation in the Hellenic region.

  2. Algal Supply System Design - Harmonized Version

    SciTech Connect

    Abodeely, Jared; Stevens, Daniel; Ray, Allison; Newby, Deborah; Schaller, Kastli

    2013-03-01

    The objective of this design report is to provide an assessment of current technologies used for production, dewatering, and converting microalgae cultivated in open-pond systems to biofuel. The original draft design was created in 2011 and has subsequently been brought into agreement with the DOE harmonized model. The design report extends beyond this harmonized model to discuss some of the challenges with assessing algal production systems, including the ability to (1) quickly assess alternative algal production system designs, (2) assess spatial and temporal variability, and (3) perform large-scale assessments considering multiple scenarios for thousands of potential sites. The Algae Logistics Model (ALM) was developed to address each of these limitations of current modeling efforts to enable assessment of the economic feasibility of algal production systems across the United States. The (ALM) enables (1) dynamic assessments using spatiotemporal conditions, (2) exploration of algal production system design configurations, (3) investigation of algal production system operating assumptions, and (4) trade-off assessments with technology decisions and operating assumptions. The report discusses results from the ALM, which is used to assess the baseline design determined by harmonization efforts between U.S. DOE national laboratories. Productivity and resource assessment data is provided by coupling the ALM with the Biomass Assessment Tool developed at PNNL. This high-fidelity data is dynamically passed to the ALM and used to help better understand the impacts of spatial and temporal constraints on algal production systems by providing a cost for producing extracted algal lipids annually for each potential site.

  3. High-order harmonic generation from the dressed autoionizing states

    NASA Astrophysics Data System (ADS)

    Fareed, M. A.; Strelkov, V. V.; Thiré, N.; Mondal, S.; Schmidt, B. E.; Légaré, F.; Ozaki, T.

    2017-07-01

    In high-order harmonic generation, resonant harmonics (RH) are sources of intense, coherent extreme-ultraviolet radiation. However, intensity enhancement of RH only occurs for a single harmonic order, making it challenging to generate short attosecond pulses. Moreover, the mechanism involved behind such RH was circumstantial, because of the lack of direct experimental proofs. Here, we demonstrate the exact quantum paths that electron follows for RH generation using tin, showing that it involves not only the autoionizing state, but also a harmonic generation from dressed-AIS that appears as two coherent satellite harmonics at frequencies +/-2Ω from the RH (Ω represents laser frequency). Our observations of harmonic emission from dressed states open the possibilities of generating intense and broadband attosecond pulses, thus contributing to future applications in attosecond science, as well as the perspective of studying the femtosecond and attosecond dynamics of autoionizing states.

  4. Tunneling ionization and harmonic generation in two-color fields

    NASA Astrophysics Data System (ADS)

    Kondo, K.; Kobayashi, Y.; Sagisaka, A.; Nabekawa, Y.; Watanabe, S.

    1996-02-01

    Tunneling ionization and harmonic generation in two-color fields were studied with a fundamental beam ( omega ) and its harmonics (2 omega ,3 omega ) , which were generated by a 100-fs Ti:sapphire laser. Ion yields of atoms and molecules were successfully controlled by means of a change in the relative phase between omega and 3 omega pulses. Two-color interference was clearly observed in photoelectron spectra and harmonic spectra. In the omega - 2 omega field even-order harmonics were observed in which the intensity was almost equal to that of the odd harmonics because of an asymmetric optical field. These results were compared with the quasi-static model for ionization and with the quantum theory for harmonic generation.

  5. Harmonic and Monogenic Potentials in Euclidean Halfspace

    NASA Astrophysics Data System (ADS)

    Brackx, F.; De Bie, H.; De Schepper, H.

    2011-09-01

    In the framework of Clifford analysis a chain of harmonic and monogenic potentials is constructed in the upper half of Euclidean space Rm+1. Their distributional limits at the boundary are computed, obtaining in this way well-known distributions in Rm such as the Dirac distribution, the Hilbert kernel, the square root of the negative Laplace operator, and the like. It is shown how each of those potentials may be recovered from an adjacent kernel in the chain by an appropriate convolution with such a distributional limit.

  6. Second harmonics HOE recording in Bayfol HX

    NASA Astrophysics Data System (ADS)

    Bruder, Friedrich-Karl; Fäcke, Thomas; Hagen, Rainer; Hönel, Dennis; Orselli, Enrico; Rewitz, Christian; Rölle, Thomas; Walze, Günther; Wewer, Brita

    2015-05-01

    Volume Holographic Optical Elements (vHOEs) provide superior optical properties over DOEs (surface gratings) due to high diffraction efficiencies in the -1st order and their excellent Bragg selectivity. Bayer MaterialScience is offering a variety of customized instant-developing photopolymer films to meet requirements for a specific optics design of a phase hologram. For instance, the photopolymer film thickness is an ideal means to adjust the angular and the spectral selectivity while the index modulation can be adopted with the film thickness to achieve a specific required dynamic range. This is especially helpful for transmission type holograms and in multiplex recordings. The selection of different substrates is helpful to achieve the overall optical properties for a targeted application that we support in B2B-focused developments. To provide further guidance on how to record volume holograms in Bayfol HX, we describe in this paper a new route towards the recording of substrate guided vHOEs by using optimized photopolymer films. Furthermore, we discuss special writing conditions that are suitable to create higher 2nd harmonic intensities and their useful applications. Due to total internal reflection (TIR) at the photopolymer-air interface in substrate guided vHOEs, hologram recording with those large diffraction angles cannot usually be done with two free-space beams. Edge-lit recording setups are used to circumvent this limitation. However, such setups require bulky recording blocks or liquid bathes and are complex and hard to align. A different approach that we present in this paper is to exploit 2nd harmonic grating generation in a freespace recording scheme. Those 2nd harmonic components allow the replay of diffraction angles that are normally only accessible with edge-lit writing configurations. Therefore, this approach significantly simplifies master recordings for vHOEs with edge-lit functionalities, which later can be used in contact copy schemes for

  7. Generating Second Harmonics In Nonlinear Resonant Cavities

    NASA Technical Reports Server (NTRS)

    Kozlovsky, William J.; Nabors, C. David; Byer, Robert L.

    1990-01-01

    Single-axial-mode lasers pump very-low-loss doubling crystals. Important advance in making resonant generation of second harmonics possible for diode-laser-pumped solid-state lasers is recent development of monolithic nonplanar ring geometries in neodymium:yttrium aluminum garnet (Nd:YAG) lasers that produce frequency-stable single-mode outputs. Other advance is development of high-quality MgO:LiNbO3 as electro-optically nonlinear material. Series of experiments devised to improve doubling efficiency of low-power lasers, and particularly of diode-laser-pumped continuous-wave Nd:YAG lasers.

  8. Higher harmonic rotor blade pitch control

    NASA Technical Reports Server (NTRS)

    Ewans, J. R.

    1976-01-01

    Tests of a model 'Reverse Velocity Rotor' system at high advance ratios and with twice-per-revolution cyclic pitch control were made under joint Navy-NASA sponsorship in the NASA, Ames 12 ft. pressure tunnel. The results showed significant gains in rotor performance at all advance ratios by using twice-per-revolution control. Detailed design studies have been made of alternative methods of providing higher harmonic motion including four types of mechanical systems and an electro-hydraulic system. The relative advantages and disadvantages are evaluated on the basis of stiffness, weight, volume, reliability and maintainability.

  9. Heat transport in active harmonic chains

    SciTech Connect

    Zheng, Mei C.; Ellis, Fred M.; Kottos, Tsampikos; Fleischmann, Ragnar; Geisel, Theo; Prosen, Tomaz

    2011-08-15

    We show that a harmonic lattice model with amplifying and attenuating elements, when coupled to two thermal baths, exhibits unique heat transport properties. Some of these novel features include anomalous nonequilibrium steady-state heat currents, negative differential thermal conductance, as well as nonreciprocal heat transport. We find that when these elements are arranged in a PT-symmetric manner, the domain of existence of the nonequilibrium steady state is maximized. We propose an electronic experimental setup based on resistive-inductive-capacitive (RLC) transmission lines, where our predictions can be tested.

  10. The defect variance of random spherical harmonics

    NASA Astrophysics Data System (ADS)

    Marinucci, Domenico; Wigman, Igor

    2011-09-01

    The defect of a function f:M\\rightarrow {R} is defined as the difference between the measure of the positive and negative regions. In this paper, we begin the analysis of the distribution of defect of random Gaussian spherical harmonics. By an easy argument, the defect is non-trivial only for even degree and the expected value always vanishes. Our principal result is evaluating the defect variance, asymptotically in the high-frequency limit. As other geometric functionals of random eigenfunctions, the defect may be used as a tool to probe the statistical properties of spherical random fields, a topic of great interest for modern cosmological data analysis.

  11. Harmonic Emission from High Power Gyrotron Oscillators.

    DTIC Science & Technology

    1984-05-01

    rd ( 0. () 2 4 39 . * .. . . a.. . . As discussed in Section 2.1, for the Gaussian ki k1l Leff/2. This relationship with the near cutoff and near...linear changes in I he IF fre- quency by equat ion (3.1). The tlilne scale onl the sCope was cal ibra 1 ed by changing 93 RD -A145 621 HARMONIC EMISSION...cial mi. lin’neaatra pro~ rd helpful in findin~g the comrwq RI: bmpfel "lr kriw" Ife .1.1. eftoai -Olvtoo %*a- fairlh *lattir In ’feur (&*#ft. *vrfil

  12. Gravitational harmonics from shallow resonant orbits

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.; Klosko, S. M.

    1977-01-01

    Gravitational constraint (lumped coefficient) equations are derived from GEOS-2 data and a detailed analysis of the shallow resonance problem. The equations follow from elementary perturbation theory and show that all such lumped coefficients are harmonic in the argument of perigee. The best along-track constraints derived from them account for all but about 2% of the 13th-order resonant information in the tracking data. The equations are also in good agreement with recent comprehensive gravity models which use substantial amounts of GEOS-2 data.

  13. Promoting Spontaneous Second Harmonic Generation through Organogelation.

    PubMed

    Marco, A Belén; Aparicio, Fátima; Faour, Lara; Iliopoulos, Konstantinos; Morille, Yohann; Allain, Magali; Franco, Santiago; Andreu, Raquel; Sahraoui, Bouchta; Gindre, Denis; Canevet, David; Sallé, Marc

    2016-07-27

    An organogelator based on the Disperse Red nonlinear optical chromophore was synthesized according to a simple and efficient three-step procedure. The supramolecular gel organization leads to xerogels which display a spontaneous second harmonic generation (SHG) response without any need for preprocessing, and this SHG activity appears to be stable over several months. These findings, based on an intrinsic structural approach, are supported by favorable intermolecular supramolecular interactions, which promote a locally non-centrosymmetric NLO-active organization. This is in sharp contrast with most materials designed for SHG purposes, which generally require the use of expensive or heavy-to-handle external techniques for managing the dipoles' alignment.

  14. Harmonic analysis of the AGS Booster imperfection

    SciTech Connect

    Shoji, Y.; Gardner, C.

    1993-12-31

    The harmonic content of magnetic field imperfections in the AGS Booster has been determined through careful measurements of the required field corrections of transverse resonances. An analysis of the required correction yielded amplitude and phase information which points to possible sources of imperfections. Dipole and quadrupole imperfections, which are proportional to the field of bending magnets (B), are mainly driven by any misalignment of the magnets. Quadrupole and sextupole imperfections, which are proportional to dB/dt, are driven by imperfections of the eddy-current correction system. The observations also suggest the presence of a remnant field.

  15. Second harmonic generation from tyrosine containing peptides

    NASA Astrophysics Data System (ADS)

    Nasir, M. N.; Bergmann, E.; Benichou, E.; Russier-Antoine, I.; Lascoux, N.; Jonin, Ch.; Besson, F.; Brevet, P. F.

    2013-10-01

    The Second Harmonic Generation (SHG) response from Tyrosine-containing peptides at the air-water interface is presented. First, the quadratic hyperpolarizability of the aromatic amino acid Tyrosine obtained by Hyper Rayleigh Scattering is reported, demonstrating its potentiality as an endogenous molecular probe for SHG studies. Then, the single Tyrosine antimicrobial peptide Mycosubtilin is monitored at the air-water interface and compared to another peptide, Surfactin, lacking a Tyrosine residue. Adsorption kinetics and polarization analysis of the SHG intensity for the peptide monolayers clearly demonstrate that the SHG response from Mycosubtilin arises from Tyrosine. Besides, it confirms that indeed Tyrosine can be targeted as an endogenous molecular probe.

  16. Two dipolar atoms in a harmonic trap

    NASA Astrophysics Data System (ADS)

    Ołdziejewski, Rafał; Górecki, Wojciech; Rzążewski, Kazimierz

    2016-05-01

    Two identical dipolar atoms moving in a harmonic trap without an external magnetic field are investigated. Using the algebra of angular momentum we reduce the problem to a simple numerics. We show that the internal spin-spin interactions between the atoms couple to the orbital angular momentum causing an analogue of the Einstein-de Haas effect. We show a possibility of adiabatically pumping our system from the s-wave to the d-wave relative motion. The effective spin-orbit coupling occurs at anti-crossings of the energy levels.

  17. Feshbach resonances of harmonically trapped atoms

    SciTech Connect

    Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro

    2011-03-15

    Employing a short-range two-channel description, we derive an analytic model of atoms in isotropic and anisotropic harmonic traps at a Feshbach resonance. On this basis we obtain a parametrization of the energy-dependent scattering length that differs from the one previously employed. We validate the model by comparison to full numerical calculations for {sup 6}Li-{sup 87}Rb and explain quantitatively the experimental observation of a resonance shift and trap-induced molecules in exited bands. Finally, we analyze the bound state admixture and Landau-Zener transition probabilities.

  18. Harmonic vector fields on pseudo-Riemannian manifolds

    NASA Astrophysics Data System (ADS)

    Friswell, R. M.; Wood, C. M.

    2017-02-01

    The theory of harmonic vector fields on Riemannian manifolds is generalised to pseudo-Riemannian manifolds. The congruence structure of conformal gradient fields on pseudo-Riemannian hyperquadrics and Killing fields on pseudo-Riemannian quadrics is elucidated, and harmonic vector fields of these two types are classified up to congruence. A para-Kähler twisted anti-isometry is used to correlate harmonic vector fields on the quadrics of neutral signature.

  19. Separation of High Order Harmonics with Fluoride Windows

    SciTech Connect

    Allison, Tom; van Tilborg, Jeroen; Wright, Travis; Hertlein, Marcus; Falcone, Roger; Belkacem, Ali

    2010-08-02

    The lower orders produced in high order harmonic generation can be effciently temporally separated into monochromatic pulses by propagation in a Fluoride window while still preserving their femtosecond pulse duration. We present calculations for MgF2, CaF2, and LiF windows for the third, fifth, and seventh harmonics of 800 nm. We demonstrate the use of this simple and inexpensive technique in a femtosecond pump/probe experiment using the fifth harmonic.

  20. The third harmonic in the Russia-Finland DC interconnection

    SciTech Connect

    Kazachkov, Yu. ); Boyarsky, A.; Kraichik, Yu. )

    1994-10-01

    During 12 years of operation of the DC back-to-back tie between Russia and Finland some undesirable phenomena at frequencies close to the third harmonic have been noticed. They may become more severe after the planned upgrading of the converter station. Steady state and transient processes with dominant third harmonic and their improvement by means of filters in the power and control circuits have been studied. Recordings of steady states with noticeable third harmonic are included.

  1. Operation of higher harmonic oscillations in free-electron lasers.

    PubMed

    Sei, N; Ogawa, H; Yamada, K

    2012-01-02

    We report for the first time the experimental achievement of a seventh-harmonic free-electron laser (FEL) oscillation. The measured FEL gains and average FEL powers for higher harmonics were identical to those calculated by a one-dimensional FEL theory. The measured linewidths of the higher-harmonic FELs were narrower than that of the fundamental FEL owing to the narrower spectral widths of the spontaneous emissions. By applying the higher-harmonic FEL oscillation to a resonator-type FEL with an advanced accelerator, an x-ray FEL oscillator can be realized at lower electron-beam energy.

  2. Harmonic analysis of spacecraft power systems using a personal computer

    NASA Technical Reports Server (NTRS)

    Williamson, Frank; Sheble, Gerald B.

    1989-01-01

    The effects that nonlinear devices such as ac/dc converters, HVDC transmission links, and motor drives have on spacecraft power systems are discussed. The nonsinusoidal currents, along with the corresponding voltages, are calculated by a harmonic power flow which decouples and solves for each harmonic component individually using an iterative Newton-Raphson algorithm. The sparsity of the harmonic equations and the overall Jacobian matrix is used to an advantage in terms of saving computer memory space and in terms of reducing computation time. The algorithm could also be modified to analyze each harmonic separately instead of all at the same time.

  3. Analysing harmonic motions with an iPhone’s magnetometer

    NASA Astrophysics Data System (ADS)

    Yavuz, Ahmet; Kağan Temiz, Burak

    2016-05-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone’s (or iPad’s) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone’s magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone’s screen using the Sensor Kinetics application. Data from this application was analysed with Eureqa software to establish the equation of the harmonic motion. Analyses show that the use of an iPhone’s magnetometer to analyse harmonic motion is a practical and effective method for small oscillations and frequencies less than 15-20 Hz.

  4. Role of Excited States In High-order Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Beaulieu, S.; Camp, S.; Descamps, D.; Comby, A.; Wanie, V.; Petit, S.; Légaré, F.; Schafer, K. J.; Gaarde, M. B.; Catoire, F.; Mairesse, Y.

    2016-11-01

    We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

  5. Nonlinear harmonic generation and proposed experimental verification in SASE FELs.

    SciTech Connect

    Biedron, S. G.; Freund, H. P.; Milton, S. V.

    1999-08-24

    Recently, a 3D, polychromatic, nonlinear simulation code was developed to study the growth of nonlinear harmonics in self-amplified spontaneous emission (SASE) free-electron lasers (FELs). The simulation was applied to the parameters for each stage of the Advanced Photon Source (APS) SASE FEL, intended for operation in the visible, UV, and short UV wavelength regimes, respectively, to study the presence of nonlinear harmonic generation. Significant nonlinear harmonic growth is seen. Here, a discussion of the code development, the APS SASE FEL, the simulations and results, and, finally, the proposed experimental procedure for verification of such nonlinear harmonic generation at the APS SASE FEL will be given.

  6. The oblate spheroidal harmonics under coordinate system rotation and translation

    NASA Astrophysics Data System (ADS)

    Panou, Georgios

    2014-05-01

    Several recent studies in geodesy and related sciences make use of oblate spheroidal harmonics. For instance, the Earth's external gravitational potential can be mathematically expanded in an oblate spheroidal harmonic series which converges outside any spheroid enclosing all the masses. In this presentation, we develop the exact relations between the solid oblate spheroidal harmonics in two coordinate systems, related to each other by an arbitrary rotation or translation. We start with the relations which exist between the spherical harmonics in the two coordinate systems. This problem has received considerable attention in the past and equivalent results have been independently derived by several investigators. Then, combining the previous results with the expressions which relate the solid spherical harmonics and the solid spheroidal harmonics, we obtain the relations under consideration. For simplicity, complex notation has been adopted throughout the work. This approach is also suitable and easy to use in the zonal harmonic expansions. The spherical harmonics under coordinate system rotation and translation are obtained as a degenerate case. The above theory can be used in any spheroidal harmonic model. Finally, some simple examples are given, in order to illuminate the mathematical derivations.

  7. High average power second harmonic generation in air

    SciTech Connect

    Beresna, Martynas; Kazansky, Peter G.; Svirko, Yuri; Barkauskas, Martynas; Danielius, Romas

    2009-09-21

    We demonstrate second harmonic vortex generation in atmospheric pressure air using tightly focused femtosecond laser beam. The circularly polarized ring-shaped beam of the second harmonic is generated in the air by fundamental beam of the same circular polarization, while the linear polarized beam produces two-lobe beam at the second harmonic frequency. The achieved normalized conversion efficiency and average second harmonic power are two orders of magnitude higher compared to those previously reported and can be increased up to 20 times by external gas flow. We demonstrate that the frequency doubling originates from the gradient of photoexcited free electrons created by pondermotive force.

  8. Application of higher harmonic blade feathering for helicopter vibration reduction

    NASA Technical Reports Server (NTRS)

    Powers, R. W.

    1978-01-01

    Higher harmonic blade feathering for helicopter vibration reduction is considered. Recent wind tunnel tests confirmed the effectiveness of higher harmonic control in reducing articulated rotor vibratory hub loads. Several predictive analyses developed in support of the NASA program were shown to be capable of calculating single harmonic control inputs required to minimize a single 4P hub response. In addition, a multiple-input, multiple-output harmonic control predictive analysis was developed. All techniques developed thus far obtain a solution by extracting empirical transfer functions from sampled data. Algorithm data sampling and processing requirements are minimal to encourage adaptive control system application of such techniques in a flight environment.

  9. Spatial Mode Control of High-Order Harmonics

    SciTech Connect

    Mercer, I.; Mevel, E.; Zerne, R.; LHuillier, A.; Antoine, P.; Wahlstroem, C. |

    1996-08-01

    We demonstrate that the spatial mode of high-order harmonics can be continuously controlled. The control is achieved by spatially modulating the degree of elliptical polarization of the fundamental field using birefringent optics. A highly sensitive relationship between the efficiency of harmonic generation and the degree of laser elliptical polarization leads to atoms emitting harmonics only in regions of linear polarization. The harmonics are emitted as annular beams whose angles of divergence can be continuously varied. {copyright} {ital 1996 The American Physical Society.}

  10. Perceptual interaction of the harmonic source and noise in voice.

    PubMed

    Kreiman, Jody; Gerratt, Bruce R

    2012-01-01

    Although the amount of inharmonic energy (noise) present in a human voice is an important determinant of vocal quality, little is known about the perceptual interaction between harmonic and inharmonic aspects of the voice source. This paper reports three experiments investigating this issue. Results indicate that perception of the harmonic slope and of noise levels are both influenced by complex interactions between the spectral shape and relative levels of harmonic and noise energy in the voice source. Just-noticeable differences (JNDs) for the noise-to-harmonics ratio (NHR) varied significantly with the NHR and harmonic spectral slope, but NHR had no effect on JNDs for NHR when harmonic slopes were steepest, and harmonic slope had no effect when NHRs were highest. Perception of changes in the harmonic source slope depended on NHR and on the harmonic source slope: JNDs increased when spectra rolled off steeply, with this effect in turn depending on NHR. Finally, all effects were modulated by the shape of the noise spectrum. It thus appears that, beyond masking, understanding perception of individual parameters requires knowledge of the acoustic context in which they function, consistent with the view that voices are integral patterns that resist decomposition.

  11. Tissue Characterization on Ultrasound Harmonic Signals using Nakagami Statistics

    NASA Astrophysics Data System (ADS)

    Lin, Fanglue; Cristea, Anca; Cachard, Christian; Basset, Olivier

    Quantitative ultrasound (QUS) imaging provides a way to characterize biological tissue. The QUS estimates can be obtained from the envelope statistics. Previous studies are mainly based on the whole backscattered signals analysis. However, the ultrasound propagation is a nonlinear process and the harmonic signals can therefore reveal the nonlinear nature of a biological medium. The present study investigates the statistics of harmonic signal envelopes to relate the distribution parameters to the nonlinear coefficients. The main results demonstrate that the distributions exhibit a different behavior for fundamental and harmonic signals and that media with different nonlinearities can be distinguished, when using Nakagami statistics on the harmonic signal envelopes.

  12. Second and third harmonic waves excited by focused Gaussian beams.

    PubMed

    Levy, Uri; Silberberg, Yaron

    2015-10-19

    Harmonic generation by tightly-focused Gaussian beams is finding important applications, primarily in nonlinear microscopy. It is often naively assumed that the nonlinear signal is generated predominantly in the focal region. However, the intensity of Gaussian-excited electromagnetic harmonic waves is sensitive to the excitation geometry and to the phase matching condition, and may depend on quite an extended region of the material away from the focal plane. Here we solve analytically the amplitude integral for second harmonic and third harmonic waves and study the generated harmonic intensities vs. focal-plane position within the material. We find that maximum intensity for positive wave-vector mismatch values, for both second harmonic and third harmonic waves, is achieved when the fundamental Gaussian is focused few Rayleigh lengths beyond the front surface. Harmonic-generation theory predicts strong intensity oscillations with thickness if the material is very thin. We reproduced these intensity oscillations in glass slabs pumped at 1550nm. From the oscillations of the 517nm third-harmonic waves with slab thickness we estimate the wave-vector mismatch in a Soda-lime glass as Δk(H)= -0.249μm(-1).

  13. Role of Excited States In High-order Harmonic Generation.

    PubMed

    Beaulieu, S; Camp, S; Descamps, D; Comby, A; Wanie, V; Petit, S; Légaré, F; Schafer, K J; Gaarde, M B; Catoire, F; Mairesse, Y

    2016-11-11

    We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

  14. Goos-Hänchen shifts in harmonic generation from metals.

    PubMed

    Yallapragada, V J; Gopal, Achanta Venu; Agarwal, G S

    2013-05-06

    We present the first calculation of the Goos-Hänchen shifts in the context of the nonlinear generation of fields. We specifically concentrate on shifts of second harmonic generated at metallic surfaces. At metallic surfaces the second harmonic primarily arises from discontinuities of the field at surfaces which not only result in large harmonic generation but also in significant Goos-Hänchen shifts of the generated second harmonic. Our results can be extended to other shifts like angular shifts and Fedorov-Imbert shifts.

  15. Perceptual interaction of the harmonic source and noise in voice

    PubMed Central

    Kreiman, Jody; Gerratt, Bruce R.

    2012-01-01

    Although the amount of inharmonic energy (noise) present in a human voice is an important determinant of vocal quality, little is known about the perceptual interaction between harmonic and inharmonic aspects of the voice source. This paper reports three experiments investigating this issue. Results indicate that perception of the harmonic slope and of noise levels are both influenced by complex interactions between the spectral shape and relative levels of harmonic and noise energy in the voice source. Just-noticeable differences (JNDs) for the noise-to-harmonics ratio (NHR) varied significantly with the NHR and harmonic spectral slope, but NHR had no effect on JNDs for NHR when harmonic slopes were steepest, and harmonic slope had no effect when NHRs were highest. Perception of changes in the harmonic source slope depended on NHR and on the harmonic source slope: JNDs increased when spectra rolled off steeply, with this effect in turn depending on NHR. Finally, all effects were modulated by the shape of the noise spectrum. It thus appears that, beyond masking, understanding perception of individual parameters requires knowledge of the acoustic context in which they function, consistent with the view that voices are integral patterns that resist decomposition. PMID:22280610

  16. Clinical Trials

    MedlinePlus

    Clinical trials are research studies that test how well new medical approaches work in people. Each study answers scientific ... screen for, diagnose, or treat a disease. Clinical trials may also compare a new treatment to a ...

  17. Comparison of transcranial brain tissue perfusion images between ultraharmonic, second harmonic, and power harmonic imaging.

    PubMed

    Shiogai, Toshiyuki; Takayasu, Natsuko; Mizuno, Toshiki; Nakagawa, Masanori; Furuhata, Hiroshi

    2004-03-01

    To clarify optimal brain tissue perfusion images visualized by transcranial ultrasound harmonic imaging, we compared gray-scale integrated backscatter (IBS) images of new ultraharmonic imaging (UHI) and conventional second harmonic imaging (SHI) with power harmonic imaging (PHI) (harmonic B-mode with harmonic power Doppler images) in 10 patients with and 4 without a temporal skull. Using a SONOS 5500 (Philips), we evaluated transient response images taken after a bolus Levovist injection at a horizontal diencephalic plane via temporal windows. Based on transmitting/receiving frequencies (MHz), 4 imaging procedures using an S3 transducer (SHI2.6 [1.3/2.6], UHI [1.3/3.6], PHI2.6 [1.3/2.6], and PHI3.2 [1.6/3.2]) and 2 imaging procedures using an S4 transducer (SHI3.6 [1.8/3.6] and PHI3.6 [1.8/3.6]) were compared in terms of size and location, peak intensity (PI), contrast area demarcation, and background image quality. In intact skull cases, gray-scale imaging tended to show larger contrast areas than PHI. A large contrast area was most frequently observed in SHI2.6 images, despite there being more high-PI cases in UHI. No contrast area with unclear background was observed in a few cases. In craniectomized cases, all contrast images tended to have large and high PI compared with the intact skull cases. PHI, particularly PHI3.6, demonstrated sharper demarcation and a clearer background than gray-scale imaging. Transcranial gray-scale SHI using a low receiving frequency of 2.6 MHz is the superior method. PHI identifies contrast area localization better than gray-scale imaging and is particularly suitable for intraoperative and postoperative cases.

  18. Limitations and improvements for harmonic generation measurements

    SciTech Connect

    Best, Steven; Croxford, Anthony; Neild, Simon

    2014-02-18

    A typical acoustic harmonic generation measurement comes with certain limitations. Firstly, the use of the plane wave-based analysis used to extract the nonlinear parameter, β, ignores the effects of diffraction, attenuation and receiver averaging which are common to most experiments, and may therefore limit the accuracy of a measurement. Secondly, the method usually requires data obtained from a through-transmission type setup, which may not be practical in a field measurement scenario where access to the component is limited. Thirdly, the technique lacks a means of pinpointing areas of damage in a component, as the measured nonlinearity represents an average over the length of signal propagation. Here we describe a three-dimensional model of harmonic generation in a sound beam, which is intended to provide a more realistic representation of a typical experiment. The presence of a reflecting boundary is then incorporated into the model to assess the feasibility of performing single-sided measurements. Experimental validation is provided where possible. Finally, a focusing acoustic source is modelled to provide a theoretical indication of the afforded advantages when the nonlinearity is localized.

  19. Tissue harmonic synthetic aperture ultrasound imaging.

    PubMed

    Hemmsen, Martin Christian; Rasmussen, Joachim Hee; Jensen, Jørgen Arendt

    2014-10-01

    Synthetic aperture sequential beamforming (SASB) and tissue harmonic imaging (THI) are combined to improve the image quality of medical ultrasound imaging. The technique is evaluated in a comparative study against dynamic receive focusing (DRF). The objective is to investigate if SASB combined with THI improves the image quality compared to DRF-THI. The major benefit of SASB is a reduced bandwidth between the probe and processing unit. A BK Medical 2202 Ultraview ultrasound scanner was used to acquire beamformed RF data for offline evaluation. The acquisition was made interleaved between methods, and data were recorded with and without pulse inversion for tissue harmonic imaging. Data were acquired using a Sound Technology 192 element convex array transducer from both a wire phantom and a tissue mimicking phantom to investigate spatial resolution and penetration. In vivo scans were also performed for a visual comparison. The spatial resolution for SASB-THI is on average 19% better than DRI-THI, and the investigation of penetration showed equally good signal-to-noise ratio. In vivo B-mode scans were made and compared. The comparison showed that SASB-THI reduces the artifact and noise interference and improves image contrast and spatial resolution.

  20. Modelling harmonic generation measurements in solids.

    PubMed

    Best, S R; Croxford, A J; Neild, S A

    2014-02-01

    Harmonic generation measurements typically make use of the plane wave result when extracting values for the nonlinearity parameter, β, from experimental measurements. This approach, however, ignores the effects of diffraction, attenuation, and receiver integration which are common features in a typical experiment. Our aim is to determine the importance of these effects when making measurements of β over different sample dimensions, or using different input frequencies. We describe a three-dimensional numerical model designed to accurately predict the results of a typical experiment, based on a quasi-linear assumption. An experiment is designed to measure the axial variation of the fundamental and second harmonic amplitude components in an ultrasonic beam, and the results are compared with those predicted by the model. The absolute β values are then extracted from the experimental data using both the simulation and the standard plane wave result. A difference is observed between the values returned by the two methods, which varies with axial range and input frequency.

  1. Second Harmonic Light Scattering from Macromolecules: Collagen.

    NASA Astrophysics Data System (ADS)

    Roth, Shmuel

    In this work we present the theory and practice of optical second harmonic generation (SHG) as applied to rat-tail tendon collagen. Our work is the first quantitative application of SHG to biological systems. The angular dependence of SHG is found to display a sharp, intense, forward peak superimposed on a broad background. The sharp peak is shown to imply long-range polar order, while the broad background corresponds to that predicted for the random "up"/"down" array of collagen fibrils seen with the electron microscope. The dependence of fibril diameter distribution on age and state of hydration is measured. Our experiments also reveal information concerning the structure of the fibrils and their arrangement in the tendon. The degree of polar order, the coherence length of tendon for harmonic generation and the absolute magnitude of the nonlinear susceptibility of the collagen fibril are also determined. The biological significance of these findings and the many advantages of SHG for the structural study of biological macromolecules and tissues are discussed.

  2. Harmonization of pre-analytical quality indicators

    PubMed Central

    Plebani, Mario; Sciacovelli, Laura; Aita, Ada; Chiozza, Maria Laura

    2014-01-01

    Quality indicators (QIs) measure the extent to which set targets are attained and provide a quantitative basis for achieving improvement in care and, in particular, laboratory services. A body of evidence collected in recent years has demonstrated that most errors fall outside the analytical phase, while the pre- and post-analytical steps have been found to be more vulnerable to the risk of error. However, the current lack of attention to extra-laboratory factors and related QIs prevent clinical laboratories from effectively improving total quality and reducing errors. Errors in the pre-analytical phase, which account for 50% to 75% of all laboratory errors, have long been included in the ‘identification and sample problems’ category. However, according to the International Standard for medical laboratory accreditation and a patient-centered view, some additional QIs are needed. In particular, there is a need to measure the appropriateness of all test request and request forms, as well as the quality of sample transportation. The QIs model developed by a working group of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) is a valuable starting point for promoting the harmonization of available QIs, but further efforts should be made to achieve a consensus on the road map for harmonization. PMID:24627719

  3. Harmonization of pre-analytical quality indicators.

    PubMed

    Plebani, Mario; Sciacovelli, Laura; Aita, Ada; Chiozza, Maria Laura

    2014-01-01

    Quality indicators (QIs) measure the extent to which set targets are attained and provide a quantitative basis for achieving improvement in care and, in particular, laboratory services. A body of evidence collected in recent years has demonstrated that most errors fall outside the analytical phase, while the pre- and post-analytical steps have been found to be more vulnerable to the risk of error. However, the current lack of attention to extra-laboratory factors and related QIs prevent clinical laboratories from effectively improving total quality and reducing errors. Errors in the pre-analytical phase, which account for 50% to 75% of all laboratory errors, have long been included in the 'identification and sample problems' category. However, according to the International Standard for medical laboratory accreditation and a patient-centered view, some additional QIs are needed. In particular, there is a need to measure the appropriateness of all test request and request forms, as well as the quality of sample transportation. The QIs model developed by a working group of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) is a valuable starting point for promoting the harmonization of available QIs, but further efforts should be made to achieve a consensus on the road map for harmonization.

  4. Balancing Vibrations at Harmonic Frequencies by Injecting Harmonic Balancing Signals into the Armature of a Linear Motor/Alternator Coupled to a Stirling Machine

    NASA Technical Reports Server (NTRS)

    Holliday, Ezekiel S. (Inventor)

    2014-01-01

    Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

  5. Field Balancing and Harmonic Vibration Suppression in Rigid AMB-Rotor Systems with Rotor Imbalances and Sensor Runout

    PubMed Central

    Xu, Xiangbo; Chen, Shao

    2015-01-01

    Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously. PMID:26334281

  6. Field Balancing and Harmonic Vibration Suppression in Rigid AMB-Rotor Systems with Rotor Imbalances and Sensor Runout.

    PubMed

    Xu, Xiangbo; Chen, Shao

    2015-08-31

    Harmonic vibrations of high-speed rotors in momentum exchange devices are primary disturbances for attitude control of spacecraft. Active magnetic bearings (AMBs), offering the ability to control the AMB-rotor dynamic behaviors, are preferred in high-precision and micro-vibration applications, such as high-solution Earth observation satellites. However, undesirable harmonic displacements, currents, and vibrations also occur in the AMB-rotor system owing to the mixed rotor imbalances and sensor runout. To compensate the rotor imbalances and to suppress the harmonic vibrations, two control methods are presented. Firstly, a four degrees-of-freedom AMB-rotor model with the static imbalance, dynamic imbalance, and the sensor runout are described. Next, a synchronous current reduction approach with a variable-phase notch feedback is proposed, so that the rotor imbalances can be identified on-line through the analysis of the synchronous displacement relationships of the geometric, inertial, and rotational axes of the rotor. Then, the identified rotor imbalances, which can be represented at two prescribed balancing planes of the rotor, are compensated by discrete add-on weights whose masses are calculated in the vector form. Finally, a repetitive control algorithm is utilized to suppress the residual harmonic vibrations. The proposed field balancing and harmonic vibration suppression strategies are verified by simulations and experiments performed on a control moment gyro test rig with a rigid AMB-rotor system. Compared with existing methods, the proposed strategies do not require trial weights or an accurate model of the AMB-rotor system. Moreover, the harmonic displacements, currents, and vibrations can be well-attenuated simultaneously.

  7. Clinical Data Acquisition Standards Harmonization importance and benefits in clinical data management

    PubMed Central

    Gaddale, Jagadeeswara Rao

    2015-01-01

    In the clinical trial process, precise and concise data collection at the source is imperative and requires statistical analysis to be performed to derive the primary and secondary endpoints. The quality of raw data collection has a direct impact on the statistical outputs generated as per the statistical analysis plan. Hence, the data collection tools used for data transcription must be clear, understandable, and precise, which helps the investigator to provide the accurate subject data. Clinical Data Acquisition Standards Harmonization (CDASH) provides guidance to develop the case report form (CRF) for domains that are commonly used for the majority of the clinical trials across the therapeutic areas. This white paper describes the importance of CDASH standards, its advantages and its impact on the efforts and the cost in designing the CRF. PMID:26623387

  8. Clinical Data Acquisition Standards Harmonization importance and benefits in clinical data management.

    PubMed

    Gaddale, Jagadeeswara Rao

    2015-01-01

    In the clinical trial process, precise and concise data collection at the source is imperative and requires statistical analysis to be performed to derive the primary and secondary endpoints. The quality of raw data collection has a direct impact on the statistical outputs generated as per the statistical analysis plan. Hence, the data collection tools used for data transcription must be clear, understandable, and precise, which helps the investigator to provide the accurate subject data. Clinical Data Acquisition Standards Harmonization (CDASH) provides guidance to develop the case report form (CRF) for domains that are commonly used for the majority of the clinical trials across the therapeutic areas. This white paper describes the importance of CDASH standards, its advantages and its impact on the efforts and the cost in designing the CRF.

  9. Harmonic millimeter radiation from a microwave FEL amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Y.-H.; Marshall, T. C.

    1997-02-01

    In this project, an electron beam is bunched at a microwave frequency and the harmonics of this bunching drive radiation at millimeter wavelengths, using a FEL, configured as a single-pass travelling wave amplifier. A 10 kW 24 GHz microwave input signal grows to ˜200 kW level using the lower-frequency unstable root of the waveguide FEL dispersion relation. The Columbia FEL facility operates at this frequency in the TE11 mode, using a helical undulator (1.85 cm period) and a 3 mm diameter 600 kV electron beam contained in a 8.7 mm ID cylindrical waveguide. The harmonic currents set up by the microwave are found to cause growth of harmonic power under two conditions. First, we choose the parameters of the device so that the upper frequency root corresponds to the third harmonic, in which case we observe a small amount of third-harmonic emission in the TE11 mode, accompanied by comparable second harmonic. The millimeter harmonic radiation produced is coherent and phase-related to the microwave source. Second, we have found substantial emission at the seventh harmonic, most likely from the TE72 mode — which, in cylindrical waveguide geometry, travels at very nearly the same wave speed as the 24 GHz TE11 power. In order to excite the seventh-harmonic radiation, the electron beam must be displaced from the system axis — ˜2 mm in this device. The seventh-harmonic output is potentially an attractive choice for a CW FEL which must generate appreciable power at ˜2 mm wavelength for plasma electron cyclotron heating since we can produce this radiation for electron beam energy as low as 400 kV. We present a theoretical model of the experiment which predicts that if the microwave signal is strong enough to drive the FEL into saturation, the harmonic emission becomes powerful.

  10. A critique of emerging European legislation in the pharmaceutical industry: a clinical trials analysis.

    PubMed

    Murray, Elizabeth; McAdam, Rodney; Burke, Moira T

    2004-01-01

    The objective of this paper is to critique emerging legislation in the pharmaceutical industry, focusing on the clinical trials sector. Possible changes are identified and discussed inrelation to their impact on phase I clinical trials conducted in the UK. It is concluded that smaller contract research organisations, which have benefited in the past from European Union legislative variation, may have resource problems in trying to cope with the changing business environment created through legislative harmonization. These SMEs must use this opportunity to seek clinical trials research partnerships in a new harmonized EU market.

  11. Generation mechanism of power line harmonic radiation

    NASA Astrophysics Data System (ADS)

    Kostrov, Alexander; Gushchin, Mikhail; Korobkov, Sergei

    The questions concerning the generation of power line harmonic radiation (PLHR) and magne-tospheric line radiation (MLR) are discussed, including the effective source of high harmonics of 50/60 Hz, and fine dynamic structure of the frequency spectrum of PLHR and MLR. It is shown, that thyristor-based power regulators used by large electrical power consumers produce the periodic sequences of current pulses with duration of about 10 microseconds in a power line. The repetition rate of these pulses is typically 100/120 Hz; the bandwidth is as broad as 100 kHz. For high harmonics of 50/60 Hz, the power line represents an effective traveling-wave (or Beverage) antenna, especially in a frequency range of several kHz corresponding to VLF whistler band in Earth ionosphere and magnetosphere. For the fixed length of the power line, which acts as antenna, radiation directivity diagram in relation to horizon depends of frequency. Hence the spatial separation of whistlers emitted at various frequencies (1-10 kHz in a consid-ered case) is possible, with subsequent propagation of whistlers with different frequencies along different L-shells. Estimations show that the efficiency of power line as travelling-wave antenna can be changed by variations of its load, but not more than twice ("weekend effect"). Since the PLHR can represent the sequence of short electromagnetic bursts, then careful se-lection of frequency-time resolution of the data acquisition equipment is needed. Typically, the time constant of the data recording and processing is too large, and the spectra of PLHR or MLR are characterized by a well-known line structure. At the same time, original bursty structure of PLHR can not be defined. Fine structure of MLR is also discussed. Frequency drift of MLR can be explained by the perturbations of the magnetospheric plasma by intense ULF waves and particle flows affecting the propagation of PLHR. Hence the physical nature of PLHR and MLR is the same, excepting the

  12. Analysing Harmonic Motions with an iPhone's Magnetometer

    ERIC Educational Resources Information Center

    Yavuz, Ahmet; Temiz, Burak Kagan

    2016-01-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone's (or iPad's) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone's magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone's screen using the "Sensor Kinetics"…

  13. R-dependent molecular harmonic generation from H2+

    NASA Astrophysics Data System (ADS)

    Feng, Liqiang; Liu, Hang

    2017-03-01

    R-dependent high-order harmonic spectra (R is the nuclear distance) from H2+ have been investigated through solving the Non-Bohn-Oppenheimer time-dependent Schrödinger equation. We found that (i) for the case of the few-cycle pulse, the harmonic emission mainly occurs from R = 3.7 to R = 6, caused by the charge-resonance-enhanced-ionization (CREI) process. (ii) For the case of the multi-cycle pulse, the harmonic emission can be separated into two parts, that is the charge-resonance-enhanced-ionization region from R = 3.7 to R = 8; and the dissociative ionization region when R > 10. (iii) Isotopic investigation showed that the R-dependent harmonic emission process can be moved towards the smaller-R region as the masses of the nuclei are increased (D2+ and T2+). (iv) Multi-minima on the harmonic spectra can be obtained, which is attributed to the two-center interference and the electron-nuclear coupling during the generation of the harmonics. The R-dependent ionization probabilities, the time-dependent nuclear motions and the time-frequency analyses of the harmonic spectra have been shown to explain the R-dependent molecular harmonic emission process.

  14. Convergence rate of spherical harmonic expansions of smooth functions

    NASA Astrophysics Data System (ADS)

    Dai, Feng; Wang, Kunyang

    2008-12-01

    We extend a well-known result of Bonami and Clerc on the almost everywhere (a.e.) convergence of Cesàro means of spherical harmonic expansions. For smooth functions measured in terms of [phi]-derivatives on the unit sphere, we obtained the sharp a.e. convergence rate of Cesàro means of their spherical harmonic expansions.

  15. Use of dominant harmonic active filters in high power applications

    NASA Astrophysics Data System (ADS)

    Cheng, Po-Tai

    The application of power electronics equipment is increasing rapidly. It is estimated that 60% of electrical power will be processed by power electronics equipment by year 2000. These equipments typically require rectifiers for AC-DC power conversion. Due to their nonlinear nature, most rectifiers draw harmonic current from the utility grid. The harmonic current causes higher energy losses, and may excite resonance conditions in the utility grid. Harmonic standards such as IEEE 519 and IEC 1000-3-2 have been proposed to regulate the harmonic current and voltage levels. This work is to develop a dominant harmonic active filter (DHAF) to realize a cost-effective active filtering solution for nonlinear loads in the range of megawatt and above. The DHAF system achieves harmonic isolation at dominant harmonic frequencies, e.g. the 5th and 7th. This approach allows use of low switching frequency and small rating active filter inverters (1%--2% of the load MVA rating) for implementation. Review of conventional passive filters and various active filters based on high bandwidth PWM inverters is provided. The control theory of the DHAF system is presented. Comparison of the DHAF system and other dominant harmonic filtering approach is provided. Simulation results and laboratory prototype test results are presented to validate the effectiveness of the proposed DHAF system.

  16. Perception and cortical neural coding of harmonic fusion in ferrets

    PubMed Central

    Kalluri, Sridhar; Depireux, Didier A.; Shamma, Shihab A.

    2008-01-01

    This study examined the perception and cortical representation of harmonic complex tones, from the perspective of the spectral fusion evoked by such sounds. Experiment 1 tested whether ferrets spontaneously distinguish harmonic from inharmonic tones. In baseline sessions, ferrets detected a pure tone terminating a sequence of inharmonic tones. After they reached proficiency, a small fraction of the inharmonic tones were replaced with harmonic tones. Some of the animals confused the harmonic tones with the pure tones at twice the false-alarm rate. Experiment 2 sought correlates of harmonic fusion in single neurons of primary auditory cortex and anterior auditory field, by comparing responses to harmonic tones with those to inharmonic tones in the awake alert ferret. The effects of spectro-temporal filtering were accounted for by using the measured spectrotemporal receptive field to predict responses and by seeking correlates of fusion in the predictability of responses. Only 12% of units sampled distinguished harmonic tones from inharmonic tones, a small percentage that is consistent with the relatively weak ability of the ferrets to spontaneously discriminate harmonic tones from inharmonic tones in Experiment 1. PMID:18529189

  17. Analysing Harmonic Motions with an iPhone's Magnetometer

    ERIC Educational Resources Information Center

    Yavuz, Ahmet; Temiz, Burak Kagan

    2016-01-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone's (or iPad's) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone's magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone's screen using the "Sensor Kinetics"…

  18. A possible generalization of the harmonic oscillator potential

    NASA Technical Reports Server (NTRS)

    Levai, Geza

    1995-01-01

    A four-parameter potential is analyzed, which contains the three-dimensional harmonic oscillator as a special case. This potential is exactly solvable and retains several characteristics of the harmonic oscillator, and also of the Coulomb problem. The possibility of similar generalizations of other potentials is also pointed out.

  19. Integrable boundary-value problems and nonlinear Fourier harmonics

    SciTech Connect

    Bikbaev, R.F.

    1995-11-10

    For the nonlinear Schrodinger equation, the integrable boundary-value problem on a segment is considered. The concept of nonlinear {theta}-harmonics similar to the ordinary Fourier harmonics in the linear case is suggested. A solution of the initial boundary-value problem on the semi-axis is constructed by means of reduction to the Cauchy problem on the whole axis.

  20. Higher order harmonic detection for exploring nonlinear interactions

    SciTech Connect

    Vasudevan, Rama K; Okatan, M. B.; Rajapaksa, Indrajit; Kim, Yunseok; Marincel, Dan; Trolier-McKinstry, Susan; Jesse, Stephen; Nagarajan, Valanoor; Kalinin, Sergei V

    2013-01-01

    Nonlinear dynamics underpin a vast array of physical phenomena ranging from interfacial motion to jamming transitions. In many cases, decoupling the contributions of competing or co-existing mechanisms to the system response can be achieved through investigation of higher order harmonics. Here, a method using band excitation scanning probe microscopy to investigate higher order harmonics of the electromechanical response, with nanometer scale spatial resolution is presented. The utility of the technique is demonstrated by probing the first three harmonics of strain for a well-known system, a model Pb(Zr1-xTix)O3 ferroelectric capacitor. It is shown that the second order harmonic response is correlated with the first harmonic response, whereas the third harmonic is not. Additionally, nanoscale measurements of the second harmonic response with field reveal significant deviations from Rayleigh-type models in the form of a much more complicated field dependence than is observed in the spatially averaged data. These results illustrate the versatility of combining proximal probe techniques with nth harmonic detection methods in exploring and decoupling nonlinear dynamics in a wide variety of nanoscale materials.

  1. Harmonization of Training in Librarianship, Information Science and Archives.

    ERIC Educational Resources Information Center

    United Nations Educational, Scientific and Cultural Organization, Paris (France). General Information Programme.

    This pamphlet is designed to show why there are many advantages in a harmonized approach to the training of archivists, librarians, and specialists in information science and what these advantages are. Following introductory discussions of the concept of harmonization, a brief history traces Unesco's role in training information professionals in…

  2. Harmonizing and Improvising in the Choral Rehearsal: A Sequential Approach

    ERIC Educational Resources Information Center

    Bell, Cindy L.

    2004-01-01

    This article challenges choral teachers to motivate their choirs to a new level of choral singing and harmonic creativity and outlines a sequential process for introducing improvisation into the daily warm-up. It argues that students can learn to harmonize and improvise by ear as part of each day's warm-up period. Sections include: (1) Chord…

  3. Harmonization: the Sample, the Measurement, and the Report

    PubMed Central

    Tate, Jillian R.; Barth, Julian H.; Jones, Graham R. D.

    2014-01-01

    Harmonization of clinical laboratory results means that results are comparable irrespective of the measurement procedure used and where or when a measurement was made. Harmonization of test results includes consideration of pre-analytical, analytical, and post-analytical aspects. Progress has been made in each of these aspects, but there is currently poor coordination of the effort among different professional organizations in different countries. Pre-analytical considerations include terminology for the order, instructions for preparation of the patient, collection of the samples, and handling and transportation of the samples to the laboratory. Key analytical considerations include calibration traceability to a reference system, commutability of reference materials used in a traceability scheme, and specificity of the measurement of the biomolecule of interest. International organizations addressing harmonization include the International Federation for Clinical Chemistry and Laboratory Medicine, the World Health Organization, and the recently formed International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR). The ICHCLR will provide a prioritization process for measurands and a service to coordinate global harmonization activities to avoid duplication of effort. Post-analytical considerations include nomenclature, units, significant figures, and reference intervals or decision values for results. Harmonization in all of these areas is necessary for optimal laboratory service. This review summarizes the status of harmonization in each of these areas and describes activities underway to achieve the goal of fully harmonized clinical laboratory testing. PMID:24790905

  4. Harmonization: the sample, the measurement, and the report.

    PubMed

    Miller, W Greg; Tate, Jillian R; Barth, Julian H; Jones, Graham R D

    2014-05-01

    Harmonization of clinical laboratory results means that results are comparable irrespective of the measurement procedure used and where or when a measurement was made. Harmonization of test results includes consideration of pre-analytical, analytical, and post-analytical aspects. Progress has been made in each of these aspects, but there is currently poor coordination of the effort among different professional organizations in different countries. Pre-analytical considerations include terminology for the order, instructions for preparation of the patient, collection of the samples, and handling and transportation of the samples to the laboratory. Key analytical considerations include calibration traceability to a reference system, commutability of reference materials used in a traceability scheme, and specificity of the measurement of the biomolecule of interest. International organizations addressing harmonization include the International Federation for Clinical Chemistry and Laboratory Medicine, the World Health Organization, and the recently formed International Consortium for Harmonization of Clinical Laboratory Results (ICHCLR). The ICHCLR will provide a prioritization process for measurands and a service to coordinate global harmonization activities to avoid duplication of effort. Post-analytical considerations include nomenclature, units, significant figures, and reference intervals or decision values for results. Harmonization in all of these areas is necessary for optimal laboratory service. This review summarizes the status of harmonization in each of these areas and describes activities underway to achieve the goal of fully harmonized clinical laboratory testing.

  5. Harmonization of Clinical Laboratory Information - Current and Future Strategies.

    PubMed

    Plebani, Mario

    2016-02-01

    According to a patient-centered viewpoint, the meaning of harmonization in the context of laboratory medicine is that the information should be comparable irrespective of the measurement procedure used and where and/or when a measurement is made. Harmonization represents a fundamental aspect of quality in laboratory medicine as its ultimate goal is to improve patient outcomes through the provision of an accurate and actionable laboratory information. Although the initial focus has to a large extent been to harmonize and standardize analytical processes and methods, the scope of harmonization goes beyond to include all other aspects of the total testing process (TTP), such as terminology and units, report formats, reference intervals and decision limits, as well as tests and test profiles request and criteria for interpretation. Two major progresses have been made in the area of harmonization in laboratory medicine: first, the awareness that harmonization should take into consideration not only the analytical phase but all steps of the TTP, thus dealing with the request, the sample, the measurement, and the report. Second, as the processes required to achieve harmonization are complicated, a systematic approach is needed. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) has played a fundamental and successful role in the development of standardized and harmonized assays, and now it should continue to work in the field through the collaboration and cooperation with many other stakeholders.

  6. Usefulness of Harmonic Focus during anterolateral thigh flap elevation.

    PubMed

    Hamahata, Atsumori; Saitou, Takashi; Kubo, Kazuyuki; Beppu, Takeshi; Yamaki, Takashi; Sakurai, Hiroyuki

    2012-11-01

    Meticulous hemostasis and careful ligation of branches are necessary for pedicle dissection during flap elevation. The aim of this study was to evaluate the effectiveness of the Harmonic Focus handpiece (Ethicon Endo-Surgery, Inc., Blue Ash, Cincinnati, OH, USA) in reducing operation time, bleeding volume, and volume of postoperative drainage during anterolateral thigh flap elevation. Ten patients requiring flap elevation were divided into two groups: (1) Harmonic Focus group (three men, two women), and (2) control group (three men, two women). Operating time was found to be lower in the Harmonic Focus group than in the control group. Bleeding volume and postoperative drainage volume were nearly identical in the Harmonic Focus group and the control group, and the number of silk ligatures was significantly lower in the Harmonic Focus group compared with the control group. Although somewhat costly, the Harmonic Scalpel with the Harmonic Focus handpiece is advantageous for flap elevation, and it is likely that Harmonic Scalpel use will increase in plastic surgery.

  7. Determination of rotor harmonic blade loads from acoustic measurements

    NASA Technical Reports Server (NTRS)

    Kasper, P. K.

    1975-01-01

    The magnitude of discrete frequency sound radiated by a rotating blade is strongly influenced by the presence of a nonuniform distribution of aerodynamic forces over the rotor disk. An analytical development and experimental results are provided for a technique by which harmonic blade loads are derived from acoustic measurements. The technique relates, on a one-to-one basis, the discrete frequency sound harmonic amplitudes measured at a point on the axis of rotation to the blade-load harmonic amplitudes. This technique was applied to acoustic data from two helicopter types and from a series of test results using the NASA-Langley Research Center rotor test facility. The inferred blade-load harmonics for the cases considered tended to follow an inverse power law relationship with harmonic blade-load number. Empirical curve fits to the data showed the harmonic fall-off rate to be in the range of 6 to 9 db per octave of harmonic order. These empirical relationships were subsequently used as input data in a compatible far field rotational noise prediction model. A comparison between predicted and measured off-axis sound harmonic levels is provided for the experimental cases considered.

  8. Data Harmonization in Aging Research: Not So Fast

    PubMed Central

    Gatz, Margaret; Reynolds, Chandra A.; Finkel, Deborah; Hahn, Chris J.; Zhou, Yan; Zavala, Catalina

    2016-01-01

    Background/Study Context Harmonizing measures in order to conduct pooled data analyses has become a scientific priority in aging research. Retrospective harmonization where different studies lack common measures of comparable constructs presents a major challenge. This study compared different approaches to harmonization with a crosswalk sample who completed multiple versions of the measures to be harmonized. Methods Through online recruitment, 1061 participants aged 30 to 98 answered two different depression scales, and 1065 participants answered multiple measures of subjective health. Rational and configural methods of harmonization were applied, using the crosswalk sample to determine their success; and empirical item response theory (IRT) methods were applied in order empirically to compare items from different measures as answered by the same person. Results For depression, IRT worked well to provide a conversion table between different measures. The rational method of extracting semantically matched items from each of the two scales proved an acceptable alternative to IRT. For subjective health, only configural harmonization was supported. The subjective health items used in most studies form a single robust factor. Conclusion Caution is required in aging research when pooling data across studies using different measures of the same construct. Of special concern are response scales that vary widely in the number of response options, especially if the anchors are asymmetrical. A crosswalk sample that has completed items from each of the measures being harmonized allows the investigator to use empirical approaches to identify flawed assumptions in rational or configural approaches to harmonizing. PMID:26524232

  9. Compact fluorescent lamps, LED lamps and harmonic distortion

    NASA Astrophysics Data System (ADS)

    Franco, A. M. R.; Debatin, R. M.; Cotia, F. C. G.; Silva, M. V. M.; Ribeiro, R. S.; Zampilis, R. R. N.

    2015-01-01

    The aim of this paper is to evaluate the harmonic distortion in the current waveform of Compact Fluorescent Lamps (CFL) and Lamps Lighting Emitting Diode (LED). For this, we analysed the power factor, voltage waveform, current waveform, total harmonic distortion (THD) and active power consumed.

  10. 78 FR 73858 - Harmon, Steven A.; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-09

    ... Energy Regulatory Commission Harmon, Steven A.; Notice of Filing Take notice that on November 27, 2013, Steven A. Harmon submitted for filing, an application for authority to hold interlocking positions...); order on reh'g, 114 FERC ] 61,142 (2006) (Order No. 664-A). Any person desiring to intervene or to...

  11. Optical Third-Harmonic Microscopy of Graphene

    NASA Astrophysics Data System (ADS)

    Dadap, Jerry I.; Hong, Sung-Young; Petrone, Nicholas W.; Yeh, Po-Chun; Hone, James C.; Osgood, Richard M., Jr.

    2013-03-01

    We report strong third-harmonic (TH) generation in monolayer graphene mounted on an amorphous silica substrate using a photon energy that is three-photon resonant with the exciton-shifted van Hove singularity at the M-point of graphene. Our polarization-dependent and azimuthal rotation measurements confirm the expected isotropic symmetry properties for the TH nonlinear optical process in graphene. Since this monolayer graphene TH signal exceeds that of bulk glass by more than two orders of magnitude, the signal contrast permits background-free scanning of graphene and provides structural information that is difficult to obtain via linear optical microscopy. We also discuss the dependence of TH signals on the number of graphene layers and compare the graphene signal strength with that from crystalline Au(111) sample. We acknowledge support from AFOSR MURI Program #FA9550-09-1-0705.

  12. Optical second harmonic generation from Pt nanowires

    NASA Astrophysics Data System (ADS)

    Hayashi, N.; Aratake, K.; Okushio, R.; Iwai, T.; Sugawara, A.; Sano, H.; Mizutani, G.

    2007-09-01

    We have measured optical second harmonic intensity from arrays of Pt nanowires of 20 nm and 9 nm average widths, as a function of the incident and output light polarizations, the azimuthal angle, and the excitation photon energy. The nanowires were fabricated through shadow deposition on self-organized NaCl(1 1 0) faceted templates. The anisotropy of the SH intensity from the Pt nanowires was found to be stronger than that from the Au nanowires reported previously. The effective nonlinear susceptibility element χ222(2), with the suffix 2 indicating the direction [1 1¯ 0], was observed for Pt nanowires, although it was not observed for Au nanowires. This difference is suggested to be due to the weaker suppression of the incident fundamental fields by the depolarization field in the Pt nanowires and the larger anisotropy in the nonlinearity of Pt nanowires due to the thinner widths.

  13. Second-harmonic generation imaging of cancer.

    PubMed

    Keikhosravi, Adib; Bredfeldt, Jeremy S; Sagar, Abdul Kader; Eliceiri, Kevin W

    2014-01-01

    The last 30 years has seen great advances in optical microscopy with the introduction of sophisticated fluorescence-based imaging methods such as confocal and multiphoton laser scanning microscopy. There is increasing interest in using these methods to quantitatively examine sources of intrinsic biological contrast including autofluorescent endogenous proteins and light interactions such as second-harmonic generation (SHG) in collagen. In particular, SHG-based microscopy has become a widely used quantitative modality for imaging noncentrosymmetric proteins such as collagen in a diverse range of tissues. Due to the underlying physical origin of the SHG signal, it is highly sensitive to collagen fibril/fiber structure and, importantly, to collagen-associated changes that occur in diseases such as cancer, fibrosis, and connective tissue disorders. An overview of SHG physics background and technologies is presented with a focused review on applications of SHG primarily as applied to cancer. © 2014 Elsevier Inc. All rights reserved.

  14. Lens-less surface second harmonic imaging

    PubMed Central

    Sly, Krystal L.; Nguyen, Trang T.; Conboy, John C.

    2012-01-01

    Lens-less surface second harmonic generation imaging (SSHGI) is used to image an SHG active molecule, (S)-( + )-1,1’-bi-2-naphthol (SBN), incorporated into a lipid bilayer patterned with the 1951 United States Air Force resolution test target. Data show the coherent plane-wave nature of SHG allows direct imaging without the aid of a lens system. Lens-less SSHGI readily resolves line-widths as small as 223 μm at an object-image distance of 7.6 cm and line-widths of 397 μm at distances as far as 30 cm. Lens-less SSHGI simplifies the detection method, raises photon collection efficiency, and expands the field-of-view. These advantages allow greater throughput and make lens-less SSHGI a potentially valuable detection method for biosensors and medical diagnostics. PMID:23037346

  15. Coherent states for the relativistic harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Aldaya, Victor; Guerrero, J.

    1995-01-01

    Recently we have obtained, on the basis of a group approach to quantization, a Bargmann-Fock-like realization of the Relativistic Harmonic Oscillator as well as a generalized Bargmann transform relating fock wave functions and a set of relativistic Hermite polynomials. Nevertheless, the relativistic creation and annihilation operators satisfy typical relativistic commutation relations of the Lie product (vector-z, vector-z(sup dagger)) approximately equals Energy (an SL(2,R) algebra). Here we find higher-order polarization operators on the SL(2,R) group, providing canonical creation and annihilation operators satisfying the Lie product (vector-a, vector-a(sup dagger)) = identity vector 1, the eigenstates of which are 'true' coherent states.

  16. Legal harmonization and reproductive tourism in Europe.

    PubMed

    Pennings, Guido

    2004-12-01

    Legislation of ethical issues illustrates the uneasy mix of ethics and politics. Although the majority has the political right to express its moral views in the law, a number of important ethical values like autonomy, tolerance and respect for other people's opinions urge the majority to take the minorities' position into account. Ignoring pluralism in society will inevitably lead to reproductive tourism. Although European legislation and harmonization in the domain of medically assisted reproduction is presented as a partial solution to this phenomenon, it is argued that European legislation should be avoided as much as possible. Regulation of these private ethical matters should be left to the national parliaments. A soft or compromise legislation will keep reproductive travelling to a minimum. Reproductive tourism is a safety valve that reduces moral conflict and expresses minimal recognition of the others' moral autonomy.

  17. Asymmetric network connectivity using weighted harmonic averages

    NASA Astrophysics Data System (ADS)

    Morrison, Greg; Mahadevan, L.

    2011-02-01

    We propose a non-metric measure of the "closeness" felt between two nodes in an undirected, weighted graph using a simple weighted harmonic average of connectivity, that is a real-valued Generalized Erdös Number (GEN). While our measure is developed with a collaborative network in mind, the approach can be of use in a variety of artificial and real-world networks. We are able to distinguish between network topologies that standard distance metrics view as identical, and use our measure to study some simple analytically tractable networks. We show how this might be used to look at asymmetry in authorship networks such as those that inspired the integer Erdös numbers in mathematical coauthorships. We also show the utility of our approach to devise a ratings scheme that we apply to the data from the NetFlix prize, and find a significant improvement using our method over a baseline.

  18. Harmonic states for the free particle

    NASA Astrophysics Data System (ADS)

    Guerrero, J.; López-Ruiz, F. F.; Aldaya, V.; Cossío, F.

    2011-11-01

    Different families of states, which are solutions of the time-dependent free Schrödinger equation, are imported from the harmonic oscillator using the quantum Arnold transformation introduced in Aldaya et al (2011 J. Phys. A: Math. Theor.44 065302). Among them, infinite series of states are given that are normalizable, expand the whole space of solutions, are spatially multi-localized and are eigenstates of a suitably defined number operator. Associated with these states new sets of coherent and squeezed states for the free particle are defined representing traveling, squeezed, multi-localized wave packets. These states are also constructed in higher dimensions, leading to the quantum mechanical version of the Hermite-Gauss and Laguerre-Gauss states of paraxial wave optics. Some applications of these new families of states and procedures to experimentally realize and manipulate them are outlined.

  19. Multivariable Harmonic Balance for Central Pattern Generators.

    PubMed

    Iwasaki, Tetsuya

    2008-12-01

    The central pattern generator (CPG) is a nonlinear oscillator formed by a group of neurons, providing a fundamental control mechanism underlying rhythmic movements in animal locomotion. We consider a class of CPGs modeled by a set of interconnected identical neurons. Based on the idea of multivariable harmonic balance, we show how the oscillation profile is related to the connectivity matrix that specifies the architecture and strengths of the interconnections. Specifically, the frequency, amplitudes, and phases are essentially encoded in terms of a pair of eigenvalue and eigenvector. This basic principle is used to estimate the oscillation profile of a given CPG model. Moreover, a systematic method is proposed for designing a CPG-based nonlinear oscillator that achieves a prescribed oscillation profile.

  20. Finite quantum kinematics of the harmonic oscillatora)

    NASA Astrophysics Data System (ADS)

    Shiri-Garakani, Mohsen; Finkelstein, David Ritz

    2006-03-01

    Arbitrarily small changes in the commutation relations suffice to transform the usual singular quantum theories into regular quantum theories. This process is an extension of canonical quantization that we call general quantization. Here we apply general quantization to the time-independent linear harmonic oscillator. The unstable Heisenberg group becomes the stable group SO(3). This freezes out the zero-point energy of very soft or very hard oscillators, like those responsible for the infrared or ultraviolet divergencies of usual field theories, without much changing the medium oscillators. It produces pronounced violations of equipartition and of the usual uncertainty relations for soft or hard oscillators, and interactions between the previously uncoupled excitation quanta of the oscillator, weakly attractive for medium quanta, strongly repulsive for soft or hard quanta.

  1. Finite quantum kinematics of the harmonic oscillator

    SciTech Connect

    Shiri-Garakani, Mohsen; Finkelstein, David Ritz

    2006-03-15

    Arbitrarily small changes in the commutation relations suffice to transform the usual singular quantum theories into regular quantum theories. This process is an extension of canonical quantization that we call general quantization. Here we apply general quantization to the time-independent linear harmonic oscillator. The unstable Heisenberg group becomes the stable group SO(3). This freezes out the zero-point energy of very soft or very hard oscillators, like those responsible for the infrared or ultraviolet divergencies of usual field theories, without much changing the medium oscillators. It produces pronounced violations of equipartition and of the usual uncertainty relations for soft or hard oscillators, and interactions between the previously uncoupled excitation quanta of the oscillator, weakly attractive for medium quanta, strongly repulsive for soft or hard quanta.

  2. Quantum channels arising from abstract harmonic analysis

    NASA Astrophysics Data System (ADS)

    Crann, Jason; Neufang, Matthias

    2013-02-01

    We present a new application of harmonic analysis to quantum information by constructing intriguing classes of quantum channels stemming from specific representations of multiplier algebras over locally compact groups G. Beginning with a representation of the measure algebra M(G), we unify and elaborate on recent counter-examples to a conjecture on the structure of fixed point subalgebras in infinite dimensions, as well as present an application to the noiseless subsystems method of quantum error correction. Using a representation of the completely bounded Fourier multiplier algebra McbA(G), we provide a new class of counter-examples to the recently solved asymptotic quantum Birkhoff conjecture, along with a systematic method of producing the examples using a geometric representation of Schur maps. Further properties of our channels including duality, quantum capacity, and entanglement preservation are discussed along with potential applications to additivity conjectures.

  3. Lens-less surface second harmonic imaging.

    PubMed

    Sly, Krystal L; Nguyen, Trang T; Conboy, John C

    2012-09-24

    Lens-less surface second harmonic generation imaging (SSHGI) is used to image an SHG active molecule, (S)-(+)-1,1'-bi-2-naphthol (SBN), incorporated into a lipid bilayer patterned with the 1951 United States Air Force resolution test target. Data show the coherent plane-wave nature of SHG allows direct imaging without the aid of a lens system. Lens-less SSHGI readily resolves line-widths as small as 223 μm at an object-image distance of 7.6 cm and line-widths of 397 μm at distances as far as 30 cm. Lens-less SSHGI simplifies the detection method, raises photon collection efficiency, and expands the field-of-view. These advantages allow greater throughput and make lens-less SSHGI a potentially valuable detection method for biosensors and medical diagnostics.

  4. Conditional Anomaly Detection with Soft Harmonic Functions.

    PubMed

    Valko, Michal; Kveton, Branislav; Valizadegan, Hamed; Cooper, Gregory F; Hauskrecht, Milos

    2011-01-01

    In this paper, we consider the problem of conditional anomaly detection that aims to identify data instances with an unusual response or a class label. We develop a new non-parametric approach for conditional anomaly detection based on the soft harmonic solution, with which we estimate the confidence of the label to detect anomalous mislabeling. We further regularize the solution to avoid the detection of isolated examples and examples on the boundary of the distribution support. We demonstrate the efficacy of the proposed method on several synthetic and UCI ML datasets in detecting unusual labels when compared to several baseline approaches. We also evaluate the performance of our method on a real-world electronic health record dataset where we seek to identify unusual patient-management decisions.

  5. Conditional Anomaly Detection with Soft Harmonic Functions

    PubMed Central

    Valko, Michal; Kveton, Branislav; Valizadegan, Hamed; Cooper, Gregory F.; Hauskrecht, Milos

    2012-01-01

    In this paper, we consider the problem of conditional anomaly detection that aims to identify data instances with an unusual response or a class label. We develop a new non-parametric approach for conditional anomaly detection based on the soft harmonic solution, with which we estimate the confidence of the label to detect anomalous mislabeling. We further regularize the solution to avoid the detection of isolated examples and examples on the boundary of the distribution support. We demonstrate the efficacy of the proposed method on several synthetic and UCI ML datasets in detecting unusual labels when compared to several baseline approaches. We also evaluate the performance of our method on a real-world electronic health record dataset where we seek to identify unusual patient-management decisions. PMID:25309142

  6. The feasibility of harmonizing gluten ELISA measurements.

    PubMed

    Rzychon, Malgorzata; Brohée, Marcel; Cordeiro, Fernando; Haraszi, Reka; Ulberth, Franz; O'Connor, Gavin

    2017-11-01

    Many publications have highlighted that routine ELISA methods do not give rise to equivalent gluten content measurement results. In this study, we assess this variation between results and its likely impact on the enforcement of the EU gluten-free legislation. This study systematically examines the feasibility of harmonizing gluten ELISA assays by the introduction of: a common extraction procedure; a common calibrator, such as a pure gluten extract and an incurred matrix material. The comparability of measurements is limited by a weak correlation between kit results caused by differences in the selectivity of the methods. This lack of correlation produces bias that cannot be corrected by using reference materials alone. The use of a common calibrator reduced the between-assay variability to some extent, but variation due to differences in selectivity of the assays was unaffected. Consensus on robust markers and their conversion to "gluten content" are required. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. [Objectives and organization of the International Conference on Harmonization].

    PubMed

    Juillet, Y

    1999-03-01

    The objective of the International Conference on Harmonization established since 1989 is to allow marketing of new drugs as soon as possible for patient benefit. At the same time harmonization decreases development time by harmonizing the content and the format of the registration file in the three regions: European Union, United States and Japan. ICH is a unique process involving health authorities and industry representatives of the three regions. The Conference which took place in July 1997 was the end of the first step of the process. At the meeting it was decided to pursue this harmonization activity, particularly in initiating a project devoted to the file format (Common Technical Document). The current period will be essentially focused on implementation of the common Guidelines and on their update in relation to scientific progress, the major part of the file now being harmonized in its content.

  8. Power grid higher-order harmonics estimation with multilayer perceptrons

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien Minh; Wira, Patrice

    2015-12-01

    This work proposes a new neural approach based on the structure of a Multi-Layer Perceptron (MLP) for identifying current harmonics in power systems. The learning approach is based on several MLP, adopts the Fourier decomposition of a signal and a training set generated from harmonic waveforms is used to calculate the weights. After training, each MLP is able to identify two coefficients for each harmonic term of the input signal. The effectiveness of the new approach is evaluated by experiments. Results show that the proposed MLPs of the new approach enable to identify effectively the amplitudes of harmonic terms from the signals under noisy condition. Results are compared to other and recent MLP approaches. The new approach can be applied in harmonic compensation strategies by being implement in an active power filter to ensure the power quality in electrical power systems.

  9. A comparison of tonsillectomy with the harmonic scalpel versus electrocautery.

    PubMed

    Morgenstein, Stuart A; Jacobs, H Kurt; Brusca, Peter A; Consiglio, Angelo R; Donzelli, Joseph; Jakubiec, James A; Donat, Terry L

    2002-10-01

    We sought to test whether the use of the harmonic scalpel would cause less pain and more rapid recovery in tonsillectomy patients versus the use of electrocautery. In a private practice community hospital, we conducted a prospective nonrandomized comparison of 156 pediatric tonsillectomy cases. Local anesthetic infiltrations and steroids were used at the discretion of the surgeon. Outcome variables consisted primarily of immediate- and mid-term pain, pain medications required, time to eating, morbidities and charges. There were no differences between the groups on an intention-to-treat basis except for costs, which were higher in the harmonic scalpel group. When rescue use of electrocautery was required to control bleeding in the in the harmonic scalpel patients, more pain and longer times to taking food were noted. Used with discretion the harmonic scalpel is equivalent to electrocautery for tonsillectomy. The harmonic scalpel does not provide a major benefit over more conventional methods of tonsillectomy.

  10. Terahertz pinch harmonics enabled by single nano rods.

    PubMed

    Park, Hyeong-Ryeol; Bahk, Young-Mi; Choe, Jong Ho; Han, Sanghoon; Choi, Seong Soo; Ahn, Kwang Jun; Park, Namkyoo; Park, Q-Han; Kim, Dai-Sik

    2011-11-21

    A pinch harmonic (or guitar harmonic) is a musical note produced by lightly pressing the thumb of the picking hand upon the string immediately after it is picked [J. Chem. Educ. 84, 1287 (2007)]. This technique turns off the fundamental and all overtones except those with a node at that location. Here we present a terahertz analogue of pinch harmonics, whereby a metallic nano rod placed at a harmonic node on a terahertz nanoresonator suppresses the fundamental mode, making the higher harmonics dominant. Strikingly, a skin depth-wide nano rod placed at the mid-point turns off all resonances. Our work demonstrates that terahertz electromagnetic waves can be tailored by nanoparticles strategically positioned, paving important path towards terahertz switching and detection applications.

  11. Integral function method for determination of nonlinear harmonic distortion

    NASA Astrophysics Data System (ADS)

    Cerdeira, Antonio; Alemán, Miguel A.; Estrada, Magali; Flandre, Denis

    2004-12-01

    The analysis of harmonic distortion is of prime importance for the analog and mixed integrated circuits. Recently we presented a new integral function method (IFM), based on a completely new principle, which allows the calculation of harmonic distortion using the DC output characteristic of devices or circuits. In this work we complement the integral function method to provide direct calculation of the following distortion figures: total harmonic distortion (THD), second harmonic distortion (HD2) and third harmonic distortion (HD3), voltage intercept points (VIP) and the intermodulation distortion (IMD). The comparison with the same distortion figures calculated by the Fourier coefficients (FC), by direct AC measurements and from FFT in simulators, indicates that results obtained by IFM give an excellent agreement in the full range of the analyzed active regions. The IFM combines simplicity and computer efficiency with accuracy and with the possibility to easily analyze the distortion when varying any of the circuit or device parameters.

  12. Spectrum of second-harmonic radiation generated from incoherent light

    SciTech Connect

    Stabinis, A.; Pyragaite, V.; Tamosauskas, G.; Piskarskas, A.

    2011-10-15

    We report on the development of the theory of second-harmonic generation by an incoherent pump with broad angular and frequency spectra. We show that spatial as well as temporal walk-off effects in a nonlinear crystal result in angular dispersion of the second-harmonic radiation. We demonstrate that the acceptance angle in second-harmonic generation by incoherent light is caused by the width of the pump angular spectrum and the resulting angular dispersion of second-harmonic radiation but does not depend on crystal length. In this case the frequency spectrum of second-harmonic radiation is determined by its angular dispersion and the pump angular spectrum. The theory is supported by an experiment in which a LiIO{sub 3} crystal was pumped by a tungsten halogen lamp.

  13. Symmetry-selective third-harmonic generation from plasmonic metacrystals.

    PubMed

    Chen, Shumei; Li, Guixin; Zeuner, Franziska; Wong, Wing Han; Pun, Edwin Yue Bun; Zentgraf, Thomas; Cheah, Kok Wai; Zhang, Shuang

    2014-07-18

    Nonlinear processes are often governed by selection rules imposed by the symmetries of the molecular configurations. The most well-known examples include the role of centrosymmetry breaking for the generation of even harmonics, and the selection rule related to the rotational symmetry in harmonic generation for fundamental beams with circular polarizations. While the role of centrosymmetry breaking in second harmonic generation has been extensively studied in plasmonic systems, the investigation of selection rules pertaining to circular polarization states of harmonic generation is limited to crystals, i.e., symmetries at the atomic level. In this Letter we demonstrate the rotational symmetry dependent third harmonic generation from nonlinear plasmonic metacrystals. We show that the selection rule can be imposed by the rotational symmetry of metacrystals embedded into an isotropic organic nonlinear thin film. The results presented here may open new avenues for designing symmetry-dependent nonlinear optical responses with tailored plasmonic nanostructures.

  14. Second harmonic generation in graphene-coated nanowires.

    PubMed

    Gao, Yixiao; Shadrivov, Ilya V

    2016-08-01

    We study second harmonic generation in a pair of graphene-coated nanowires. We show that the phase matching condition for harmonic generation can be engineered in a wide range of frequencies by tuning the spacing between graphene nanowires. We derive coupled mode equations describing the process of second harmonic generation using an unconjugated Lorentz reciprocity theorem. We show that the highest harmonic generation efficiency can be achieved by phase matching the fundamental mode with the two lowest order symmetric modes at the second harmonic frequency. Despite losses in graphene, we predict that the efficiency can be further enhanced by reducing the radius of nanowires due to larger mode overlap and lower propagation loss.

  15. Decameter U-burst Harmonic Pair from a High Loop

    NASA Astrophysics Data System (ADS)

    Dorovskyy, V. V.; Melnik, V. N.; Konovalenko, A. A.; Bubnov, I. N.; Gridin, A. A.; Shevchuk, N. V.; Rucker, H. O.; Poedts, S.; Panchenko, M.

    2015-01-01

    The results of the first observations of solar sporadic radio emission within 10 - 70 MHz by the Giant Ukrainian Radio Telescope (GURT) are presented and discussed. Observations in such a wide range of frequencies considerably facilitate the registration of harmonic pairs. The solar U-burst harmonic pair observed on 8 August 2012 is analyzed. The burst key features were determined. Among them, the time delay between the fundamental and harmonic emissions was of special interest. The fundamental emission was delayed for 7 s with respect to the harmonic emission. A model for explaining the occurrence of such a delay is proposed, in which the emission source is located inside a magnetic loop containing plasma of increased density. In this case, the delay appears due to the difference in group velocities of electromagnetic waves at the fundamental and the harmonic frequencies.

  16. Finite quantum theory of the harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Shiri-Garakani, Mohsen

    We apply the Segal process of group simplification to the linear harmonic oscillator. The result is a finite quantum theory with three quantum constants h, h', h″ instead of the usual one. We compare the classical (CLHO), quantum (QLHO), and finite (FLHO) linear harmonic oscillators and their canonical or unitary groups. The FLHO is isomorphic to a dipole rotator with N = l(l + 1) ˜ 1/(h ' h″) states and Hamiltonian H = A(Lx)2 + B(Ly)2, and the physically interesting case has N ≫ 1. The position and momentum variables are quantized with uniform finite spectra. For fixed quantum constants and large N ≫ 1 there are three broad classes of FLHO: soft, medium, and hard, with B/A ≪ 1, B/A ˜ 1, and B/A ≫ 1 respectively. The field oscillators responsible for infra-red and ultraviolet divergences are soft and hard respectively. Medium oscillators have B/A ˜ 1 and approximate the QLHO. They have ˜ N low-lying states with nearly the same zero-point energy and level spacing as the QLHO, and nearly obeying the Heisenberg uncertainty principle and the equipartition principle. The corresponding rotators are nearly polarized along the z axis with Lz ˜ +/-l. The soft and hard FLHO's have infinitesimal 0-point energy and grossly violate equipartition and the Heisenberg uncertainty principle. They do not resemble the QLHO at all. Their low-lying energy states correspond to rotators with Lx ˜ 0 or Ly ˜ 0 instead of Lz ˜ +/-l. Soft oscillators have frozen momentum, because their maximum potential energy is too small to produce one quantum of momentum. Hard oscillators have frozen position, because their maximum kinetic energy is too small to excite one quantum of position.

  17. Enhanced third harmonic generation with graphene metasurfaces

    NASA Astrophysics Data System (ADS)

    Jin, Boyuan; Guo, Tianjing; Argyropoulos, Christos

    2017-09-01

    The nonlinear responses of different materials provide useful mechanisms for optical switching, low noise amplification, and harmonic frequency generation. However, the nonlinear processes usually have an extremely weak nature and require high input power to be excited. To alleviate this severe limitation, we propose new designs of ultrathin nonlinear metasurfaces composed of patterned graphene micro-ribbons to significantly enhance third harmonic generation (THG) at far-infrared and terahertz (THz) frequencies. The incident wave is tightly confined and significantly boosted along the surface of graphene in these configurations due to the excitation of highly localized plasmons. The bandwidth of the resonant response becomes narrower due to the introduction of a metallic substrate below the graphene micro-ribbons, which leads to zero transmission and standing waves inside the intermediate dielectric spacer layer. The enhancement of the incident field, combined with the large nonlinear conductivity of graphene, can dramatically increase the THG conversion efficiency by several orders of magnitude. In addition, the resonant frequency of the metasurface can be adjusted by dynamically tuning the Fermi energy of graphene via electrical or chemical doping. As a result, the THG wave can be optimized and tuned to be emitted at different frequencies without the need to change the nonlinear metasurface geometry. The proposed nonlinear metasurfaces provide a new way to realize compact and efficient nonlinear sources at the far-infrared and THz frequency ranges, as well as new frequency generation and wave mixing devices which are expected to be useful for nonlinear THz spectroscopy and noninvasive THz imaging applications.

  18. Macroscopic control of quantum paths in high order harmonics by a weak second harmonic field.

    PubMed

    Wang, Shaoyi; Zhang, Qingbin; Hong, Weiyi; Zhu, Xiaosong; Lu, Peixiang

    2011-12-05

    The phase matching of quantum paths in high-order harmonic generation is investigated in a two-color laser field. Our results show that the phase-matching properties of the short and long trajectories can be modulated effectively by adding a weak second harmonic field. This scheme can not only achieve the quantum path selection, but more importantly it can achieve on-axis phase matching for both of the two trajectories simultaneously. A bright interference pattern induced by the simultaneously phase-matched two trajectories can be observed by placing a near-field on-axis filter, which has great potential for experimentally characterizing the full single-atom dipole moment.

  19. Standardized and flexible eight colour flow cytometry panels harmonized between different laboratories to study human NK cell phenotype and function.

    PubMed

    Veluchamy, John P; Delso-Vallejo, María; Kok, Nina; Bohme, Fenna; Seggewiss-Bernhardt, Ruth; van der Vliet, Hans J; de Gruijl, Tanja D; Huppert, Volker; Spanholtz, Jan

    2017-03-10

    Advancements in multi-colour fluorescence activated cell sorting (FACS) panel warrant harmonized procedures to obtain comparable data between various laboratories. The intensifying clinical exploration of Natural Killer (NK) cell-based immunotherapy demands standardized and harmonized NK cell FACS panels and acquisition protocols. Eight colour FACS panels were designed to study human NK cell phenotype and function within peripheral blood mononuclear cells (PBMC). The panels were designed around fixed backbone markers and channels, covering antigens for non-NK lineage exclusion (CD3, TCRγδ, CD19, CD14, SYTOX(®) Blue) and NK cell selection (CD45, CD56, CD16), complemented with variable drop-in markers/channels to study NK cell phenotype (NKG2A, NKG2C, NKG2D and KIR2D) or NK cell function and activation (CD25, NKp44 and CD107a). Harmonized FACS set-up and data analysis for three different flow cytometers has been established, leading to highly comparable and reproducible data sets using the same PBMC reference samples (n = 6). Further studies of NK cells in fresh or cryopreserved PBMC samples (n = 12) confirmed that freezing and thawing of PBMC samples did not significantly affect NK phenotype or function. In conclusion, our data demonstrate that cryopreserved PBMC samples analysed by standardized FACS panels and harmonized analysis protocols will generate highly reliable data sets for multi-center clinical trials under validated conditions.

  20. Standardized and flexible eight colour flow cytometry panels harmonized between different laboratories to study human NK cell phenotype and function

    PubMed Central

    Veluchamy, John P.; Delso-Vallejo, María; Kok, Nina; Bohme, Fenna; Seggewiss-Bernhardt, Ruth; van der Vliet, Hans J.; de Gruijl, Tanja D.; Huppert, Volker; Spanholtz, Jan

    2017-01-01

    Advancements in multi-colour fluorescence activated cell sorting (FACS) panel warrant harmonized procedures to obtain comparable data between various laboratories. The intensifying clinical exploration of Natural Killer (NK) cell-based immunotherapy demands standardized and harmonized NK cell FACS panels and acquisition protocols. Eight colour FACS panels were designed to study human NK cell phenotype and function within peripheral blood mononuclear cells (PBMC). The panels were designed around fixed backbone markers and channels, covering antigens for non-NK lineage exclusion (CD3, TCRγδ, CD19, CD14, SYTOX® Blue) and NK cell selection (CD45, CD56, CD16), complemented with variable drop-in markers/channels to study NK cell phenotype (NKG2A, NKG2C, NKG2D and KIR2D) or NK cell function and activation (CD25, NKp44 and CD107a). Harmonized FACS set-up and data analysis for three different flow cytometers has been established, leading to highly comparable and reproducible data sets using the same PBMC reference samples (n = 6). Further studies of NK cells in fresh or cryopreserved PBMC samples (n = 12) confirmed that freezing and thawing of PBMC samples did not significantly affect NK phenotype or function. In conclusion, our data demonstrate that cryopreserved PBMC samples analysed by standardized FACS panels and harmonized analysis protocols will generate highly reliable data sets for multi-center clinical trials under validated conditions. PMID:28281564

  1. Gastrectomy and D2 Lymphadenectomy for Gastric Cancer: A Meta-Analysis Comparing the Harmonic Scalpel to Conventional Techniques.

    PubMed

    Cheng, Hang; Hsiao, Chia-Wen; Clymer, Jeffrey W; Schwiers, Michael L; Tibensky, Bryanna N; Patel, Leena; Ferko, Nicole C; Chekan, Edward

    2015-01-01

    The ultrasonic Harmonic scalpel has demonstrated clinical and surgical benefits in dissection and coagulation. To evaluate its use in gastrectomy, we conducted a systematic review and meta-analysis of randomized controlled trials comparing the Harmonic scalpel to conventional techniques in gastrectomy for patients with gastric cancer. International databases were searched without language restrictions for comparisons in open or laparoscopic gastrectomy and lymphadenectomy. The meta-analysis used a random-effects model for all outcomes; continuous variables were analyzed for mean differences and dichotomous variables were analyzed for risk ratios. Sensitivity analyses were conducted for study quality, type of conventional technique, and imputation of study results. Ten studies (N = 935) met the inclusion criteria. Compared with conventional hemostatic techniques, the Harmonic scalpel demonstrated significant reductions in operating time (-27.5 min; P < 0.001), intraoperative blood loss (-93.2 mL; P < 0.001), and drainage volume (-138.8 mL; P < 0.001). Results were numerically higher for conventional techniques for hospital length of stay, complication risk, and transfusions but did not reach statistical significance. Results remained robust to sensitivity analyses. This meta-analysis demonstrates the clear advantages of using the Harmonic scalpel compared to conventional techniques, with improvements demonstrated across several outcome measures for patients undergoing gastrectomy and lymphadenectomy.

  2. Comparing differential tissue harmonic imaging with tissue harmonic and fundamental gray scale imaging of the liver.

    PubMed

    Chiou, See-Ying; Forsberg, Flemming; Fox, Traci B; Needleman, Laurence

    2007-11-01

    The purpose of this study was to compare fundamental gray scale sonography, tissue harmonic imaging (THI), and differential tissue harmonic imaging (DTHI) for depicting normal and abnormal livers. The in vitro lateral resolution of DTHI, THI, and sonography was assessed in a phantom. Sagittal and transverse images of right and left hepatic lobes of 5 volunteers and 20 patients and images of 27 liver lesions were also acquired. Three independent blinded readers scored all randomized images for noise, detail resolution, image quality, and margin (for lesions) on a 7-point scale. Next, images from the same location obtained with all 3 modes were compared blindly side by side and rated by all readers. Contrast-to-noise ratios were calculated for the lesions, and the depth of penetration (centimeters) was determined for all images. In vitro, the lateral resolution of DTHI was significantly better than fundamental sonography (P = .009) and showed a trend toward significance versus THI (P = .06). In the far field, DTHI performed better than both modes (P < .04). In vivo, 450 images were scored, and for all parameters, DTHI and THI did better than sonography (P < .002). Differential tissue harmonic imaging scored significantly higher than THI with regard to detail resolution and image quality (P < .001). The average increase in penetration with THI and DTHI was around 0.6 cm relative to sonography (P < .0001). The contrast-to-noise ratio for DTHI showed a trend toward significance versus THI (P = .06). Side-by-side comparisons rated DTHI better than THI and sonography in 54% of the cases (P < .007). Tissue harmonic imaging and DTHI do better than fundamental sonography for hepatic imaging, with DTHI being rated the best of the 3 techniques.

  3. Bounce-harmonic Landau Damping of Plasma Waves

    NASA Astrophysics Data System (ADS)

    Anderegg, Francois

    2015-11-01

    We present measurement of plasma wave damping, spanning the temperature regimes of direct Landau damping, bounce-harmonic Landau damping, inter-species drag damping, and viscous damping. Direct Landau damping is dominant at high temperatures, but becomes negligible as v harmonics damping, controlled by an applied ``squeeze'' potential, which generates harmonics in the wave potential and in the particle dynamics. A particle moving in z experiences a non-sinusoidal mode potential caused by the squeeze, producing high spatial harmonics with lower phase velocity. These harmonics are Landau damped even when the mode phase velocity vph is large compared to the thermal velocity v , since the nth harmonic is resonant with a particle bouncing at velocity vb =vph / n . Here we increase the bounce harmonics through applied squeeze potential; but some harmonics are always present in finite length systems. For our centered squeeze geometry, theory shows that only odd harmonics are generated, and predicts the Landau damping rate from vph / n . Experimentally, the squeeze potential increases the wave damping and reduces its frequency. The frequency shift occurs because the squeeze potential reduces the number of particle where the mode velocity is the largest, therefore reducing the mode frequency. We observe an increase in the damping proportional to Vs2,and a frequency reduction proportional to Vs , in quantitative agreement with theory. Wave-coherent laser induced fluorescence allows direct observation of bounce resonances on the particle distribution, here predominantly at vph / 3 . A clear increase of the bounce harmonics is visible on the particle distribution when the squeeze potential is applied. Supported by NSF Grant PHY-1414570, and DOE Grants DE-SC0002451 and DE-SC0008693.

  4. The ultrasonic harmonic scalpel for circumcision: experimental evaluation using dogs

    PubMed Central

    Peng, Mou; Meng, Zhe; Yang, Zhong-Hua; Wang, Xing-Huan

    2013-01-01

    Male circumcision is one of the most commonly performed operations worldwide, and many novel techniques have been developed for better postoperative outcomes. The purpose of this study was to explore the feasibility of applying the ultracision harmonic scalpel (UHS) for circumcision by using dogs. Sixteen adult male dogs were divided into two groups: the UHS group and the control group. The dogs were circumcised with either the UHS or a conventional scalpel. The UHS circumcision procedure and the effects were imaged 1 week after surgery. The two groups were compared with respect to the operative time and volume of blood loss. Postoperative complications, including oedema, infection, bleeding of the incision and wound dehiscence, were recorded for both groups. The mean operative time for the UHS group was only 5.1 min compared with the 35.5 min of the conventional group. The mean blood loss was less than 2 ml for the UHS group and 15 ml for the conventional group. There was only one case of mild oedema in the UHS group, but the postoperative complications in the conventional group included two cases of mild oedema, one infection of the incision and one case of bleeding of the incision. In conclusion, circumcision using UHS is a novel technique to treat patients with phimosis and excessive foreskin, and this method has a short operative time, less blood loss and fewer complications than the conventional scalpel method. This small animal study provides a basis for embarking on a larger-scale clinical trial of the UHS. PMID:23042449

  5. The ultrasonic harmonic scalpel for circumcision: experimental evaluation using dogs.

    PubMed

    Peng, Mou; Meng, Zhe; Yang, Zhong-Hua; Wang, Xing-Huan

    2013-01-01

    Male circumcision is one of the most commonly performed operations worldwide, and many novel techniques have been developed for better postoperative outcomes. The purpose of this study was to explore the feasibility of applying the ultracision harmonic scalpel (UHS) for circumcision by using dogs. Sixteen adult male dogs were divided into two groups: the UHS group and the control group. The dogs were circumcised with either the UHS or a conventional scalpel. The UHS circumcision procedure and the effects were imaged 1 week after surgery. The two groups were compared with respect to the operative time and volume of blood loss. Postoperative complications, including oedema, infection, bleeding of the incision and wound dehiscence, were recorded for both groups. The mean operative time for the UHS group was only 5.1 min compared with the 35.5 min of the conventional group. The mean blood loss was less than 2 ml for the UHS group and 15 ml for the conventional group. There was only one case of mild oedema in the UHS group, but the postoperative complications in the conventional group included two cases of mild oedema, one infection of the incision and one case of bleeding of the incision. In conclusion, circumcision using UHS is a novel technique to treat patients with phimosis and excessive foreskin, and this method has a short operative time, less blood loss and fewer complications than the conventional scalpel method. This small animal study provides a basis for embarking on a larger-scale clinical trial of the UHS.

  6. Evidence of high harmonics from echo-enabled harmonic generation for seeding x-ray free electron lasers.

    PubMed

    Xiang, D; Colby, E; Dunning, M; Gilevich, S; Hast, C; Jobe, K; McCormick, D; Nelson, J; Raubenheimer, T O; Soong, K; Stupakov, G; Szalata, Z; Walz, D; Weathersby, S; Woodley, M

    2012-01-13

    Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science.

  7. Evidence of High Harmonics from Echo-Enabled Harmonic Generation for Seeding X-ray Free Electron Lasers

    SciTech Connect

    Xiang, D.; Colby, E.; Dunning, M.; Gilevich, S.; Hast, C.; Jobe, K.; McCormick, D.; Nelson, J.; Raubenheimer, T.O.; Soong, K.; Stupakov, G.; Szalata, Z.; Walz, D.; Weathersby, S.; Woodle, M.; /SLAC

    2012-02-15

    Echo-enabled harmonic generation free electron lasers hold great promise for the generation of fully coherent radiation in x-ray wavelengths. Here we report the first evidence of high harmonics from the echo-enabled harmonic generation technique in the realistic scenario where the laser energy modulation is comparable to the beam slice energy spread. In this experiment, coherent radiation at the seventh harmonic of the second seed laser is generated when the energy modulation amplitude is about 2-3 times the slice energy spread. The experiment confirms the underlying physics of echo-enabled harmonic generation and may have a strong impact on emerging seeded x-ray free electron lasers that are capable of generating laserlike x rays which will advance many areas of science.

  8. Harmonic tracking of acoustic radiation force-induced displacements.

    PubMed

    Doherty, Joshua R; Dahl, Jeremy J; Trahey, Gregg E

    2013-11-01

    Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse-inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse-inversion techniques. The method is implemented with acoustic radiation force impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8-MHz harmonic images created using a band-pass filter approach and the fully sampled pulse-inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower- and higher-frequency methods suggests that any improvement resulting from the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse-inversion harmonic ARFI images. Within the lumen, the harmonic tracking

  9. Harmonic Tracking of Acoustic Radiation Force Induced Displacements

    PubMed Central

    Doherty, Joshua R.; Dahl, Jeremy J.; Trahey, Gregg E.

    2014-01-01

    Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse inversion techniques. The method is implemented with Acoustic Radiation Force Impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8 MHz harmonic images created using a bandpass filter approach and the fully sampled pulse inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower and higher frequency methods suggests that any improvement due to the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse inversion harmonic ARFI images. Within the lumen, the harmonic tracking methods

  10. Effect of ultrarelativistic laser beam filamentation on third harmonic spectrum

    NASA Astrophysics Data System (ADS)

    Gupta, Ruchika; Sharma, Prerana; Chauhan, Prashant K.; Rafat, M.; Sharma, R. P.

    2009-04-01

    This paper investigates the generation of plasma wave and third harmonic generation in a hot collision less plasma by an intense laser beam. On the account of the V→×B→ force, a plasma wave at 2ω0 (here ω0 is the pump laser frequency) is generated. The solution of the pump laser beam has been obtained within the nonparaxial ray approximation. Filamentary structures of the laser beam are observed due to relativistic nonlinearity. By expanding the eikonal and the other relevant quantities up to the fourth power of r it is observed that the focusing of the laser beams become fast in the nonparaxial region. Interaction of the plasma wave with the incident laser beam generates the third harmonics. The mechanism of the plasma wave, third harmonic generation, and the parameters, which govern the third harmonic yield and hence the spectrum of third harmonics, have been studied in detail. Correlation of the third harmonic spectrum with the filamentation has been pointed out. Therefore, the broadening of the third harmonic spectra can be used as a diagnostic tool to study the presence of the filamentation of laser beams in laser plasma experiments.

  11. Effect of ultrarelativistic laser beam filamentation on third harmonic spectrum

    SciTech Connect

    Gupta, Ruchika; Rafat, M.; Sharma, Prerana; Chauhan, Prashant K.; Sharma, R. P.

    2009-04-15

    This paper investigates the generation of plasma wave and third harmonic generation in a hot collision less plasma by an intense laser beam. On the account of the V-vectorxB-vector force, a plasma wave at 2{omega}{sub 0} (here {omega}{sub 0} is the pump laser frequency) is generated. The solution of the pump laser beam has been obtained within the nonparaxial ray approximation. Filamentary structures of the laser beam are observed due to relativistic nonlinearity. By expanding the eikonal and the other relevant quantities up to the fourth power of r it is observed that the focusing of the laser beams become fast in the nonparaxial region. Interaction of the plasma wave with the incident laser beam generates the third harmonics. The mechanism of the plasma wave, third harmonic generation, and the parameters, which govern the third harmonic yield and hence the spectrum of third harmonics, have been studied in detail. Correlation of the third harmonic spectrum with the filamentation has been pointed out. Therefore, the broadening of the third harmonic spectra can be used as a diagnostic tool to study the presence of the filamentation of laser beams in laser plasma experiments.

  12. A Primer on the Physical Principles of Tissue Harmonic Imaging.

    PubMed

    Anvari, Arash; Forsberg, Flemming; Samir, Anthony E

    2015-01-01

    Tissue harmonic imaging (THI) is a routinely used component of diagnostic ultrasonography (US). In this method, higher-frequency harmonic waves produced by nonlinear fundamental US wave propagation are used to generate images that contain fewer artifacts than those seen on conventional fundamental wave US tissue imaging. Harmonic frequencies are integer multiples of the fundamental frequency. The majority of current clinical US systems use second harmonic echoes for THI image formation. Image processing techniques (ie, bandwidth receive filtering, pulse inversion, side-by-side phase cancellation, and pulse-coded harmonics) are used to eliminate the fundamental frequency echoes, and the remaining harmonic frequency data are used to generate the diagnostic image. Advantages of THI include improved signal-to-noise ratio and reduced artifacts produced by side lobes, grating lobes, and reverberation. THI has been accepted in US practice, and variations of the technology are available on most US systems typically used for diagnostic imaging in radiologic practice. Differential THI is a further improvement that combines the advantages of THI, including superior tissue definition and reduced speckle artifact, with the greater penetration of lower frequency US, which permits high-quality harmonic imaging at greater depth than could previously be performed with conventional THI. (©)RSNA, 2015.

  13. Elastography using harmonic ultrasonic imaging: a feasibility study.

    PubMed

    Desai, Raghavendra Reddy; Krouskop, Thomas A; Righetti, Raffaella

    2010-04-01

    Tissue Harmonic Imaging (THI) is a relatively new modality that has had a significant impact in the ultrasound field. In the recent past, imaging the mechanical properties of tissues using elastography has also gained great interest. In this paper, we investigate the feasibility of combining these two state-of-the-art ultrasound-imaging modalities. The performance of elastograms obtained using harmonic ultrasonic signals is studied with simulations and compared to the performance of conventional elastograms using standard statistical methods. Experiments are used as a proof of the technical feasibility of generating tissue-harmonic elastograms using experimental harmonic signals. The results of our simulation study indicate that all image quality factors considered in this study (elastographic signal-to-noise ratio, elastographic contrast-to-noise ratio and spatial resolution) may be improved when using harmonic ultrasonic signals, provided that the ultrasound system is characterized by high bandwidth, high sampling frequency and large lateral sampling. Preliminary experimental results suggest that it is technically feasible to generate experimental elastograms using harmonic signals, provided that the sonographic signal-to-noise ratio of the pre- and postcompression harmonic frames is sufficiently high to guarantee reliable values of correlation.

  14. Responses of inferior colliculus neurons to double harmonic tones.

    PubMed

    Sinex, Donal G; Li, Hongzhe

    2007-12-01

    The auditory system can segregate sounds that overlap in time and frequency, if the sounds differ in acoustic properties such as fundamental frequency (f0). However, the neural mechanisms that underlie this ability are poorly understood. Responses of neurons in the inferior colliculus (IC) of the anesthetized chinchilla were measured. The stimuli were harmonic tones, presented alone (single harmonic tones) and in the presence of a second harmonic tone with a different f0 (double harmonic tones). Responses to single harmonic tones exhibited no stimulus-related temporal pattern, or in some cases, a simple envelope modulated at f0. Responses to double harmonic tones exhibited complex slowly modulated discharge patterns. The discharge pattern varied with the difference in f0 and with characteristic frequency. The discharge pattern also varied with the relative levels of the two tones; complex temporal patterns were observed when levels were equal, but as the level difference increased, the discharge pattern reverted to that associated with single harmonic tones. The results indicated that IC neurons convey information about simultaneous sounds in their temporal discharge patterns and that the patterns are produced by interactions between adjacent components in the spectrum. The representation is "low-resolution," in that it does not convey information about single resolved components from either individual sound.

  15. Sparse codes of harmonic natural sounds and their modulatory interactions.

    PubMed

    Terashima, Hiroki; Hosoya, Haruo

    2009-01-01

    Sparse coding and its related theories have been successful to explain various response properties of early stages of sensory information processing such as primary visual cortex and peripheral auditory system, which suggests that the emergence of such properties results from adaptation of the nerve system to natural stimuli. The present study continues this line of research in a higher stage of auditory processing, focusing on harmonic structures that are often found in behaviourally important natural sound like animal vocalization. It has been physiologically shown that monkey primary auditory cortices (A1) have neurons with response properties capturing such harmonic structures: their response and modulation peaks are often found at frequencies that are harmonically related to each other. We hypothesize that such relations emerge from sparse coding of harmonic natural sounds. Our simulation shows that similar harmonic relations emerge from frequency-domain sparse codes of harmonic sounds, namely, piano performance and human speech. Moreover, the modulatory behaviours can be explained by competitive interactions of model neurons that capture partially common harmonic structures.

  16. Harmonization of laboratory testing - Current achievements and future strategies.

    PubMed

    Tate, Jillian R; Johnson, Roger; Barth, Julian; Panteghini, Mauro

    2014-05-15

    Harmonization in laboratory testing is more far-reaching than merely analytical harmonization. It includes all aspects of the total testing process from the "pre-pre-analytical" phase through analysis to the "post-post-analytical" phase. Harmonizing the pre-analytical phase requires use of standardized operating procedures for correct test selection, sample collection and handling, while standardized test terminology, and units and traceability to ISO standard 17511 are required to ensure equivalency of measurement results. Use of harmonized reference intervals and decision limits for analytes where platforms share allowable bias requirements will reduce inaccurate clinical interpretation and unnecessary laboratory testing. In the post-analytical phase, harmonized procedures for the management of critical laboratory test results are required to improve service quality and ensure patient safety. Monitoring of the outcomes of harmonization activities is through surveillance by external quality assessment schemes that use commutable materials and auditing of the "pre-pre-analytical" and "post-post-analytical" phases. Successful implementation of harmonization in laboratory testing requires input by all stakeholders, including the clinical laboratory community, diagnostics industry, clinicians, professional societies, IT providers, consumer advocate groups and governmental bodies.

  17. Multi-harmonic electron cyclotron instabilities. [diffuse electron aurora

    NASA Technical Reports Server (NTRS)

    Ashour-Abdalla, M.; Kennel, C. F.

    1978-01-01

    The reported investigation constitutes an extension of studies conducted by Ashour-Abdalla and Kennel (1975, 1976, 1978) with respect to a basic plasma model of Young et al. (1973). The model involves a combination of a cold Maxwellian background plasma, a hot plasma, and a 'loss cone' type of free energy source. Previous results on the first cyclotron harmonic bands are extended to multiharmonics. The significance of the obtained relations is discussed and tentative conclusions are presented. Given that the spatial growth rates of the convective modes are comparable, and that simultaneous nonconvective instability (NCI) is possible, it is concluded that multiharmonic emissions ought to be a common feature of the magnetospheric electrostatic wave observations. Since the volume of parameter space for which the first harmonic is NCI, and the volume for which the convective first harmonic mode has significant spatial growth rates, exceed those for the higher harmonics, first harmonic waves should be the most commonly observed and the higher harmonics should usually be accompanied by the first harmonic.

  18. Test of circuit breakers under harmonic loading conditions. Final report

    SciTech Connect

    Estrada, T.; Briggs, S.J.; Khosla, N.

    1995-11-01

    Harmonic currents in Army installation power systems can cause voltage distortion, overheating of system components, and load disruption. The U.S. Army Center for Public Works also has periodically received reports of unexplained nuisance circuit breaker tripping, which in theory might be caused by harmonics. No industry standard literature is available on the behavior of circuit breakers under harmonic loading conditions, however. The objective of this work was to test the effects of harmonic loading conditions on three common types of low voltage, molded case circuit breakers used indoors on Army installations: thermal magnetic, magnetic only, and solid state. This experiment detected no nuisance tripping with any of the breakers tested. Additionally it was found that varying harmonic loading conditions did not affect manufacturer specified trip times for thermal magnetic or solid state circuit breakers. However, under moderate overload conditions, the same experimental harmonic conditions caused hazardous overheating and trip failure in the magnetic only circuit breakers. Based on a review of related nonexperimental industry literature on circuit breaker design and performance, the authors postulate that inherent design characteristics leave thermal magnetic and solid state circuit breakers unaffected by harmonics. The literature also suggests that the construction of the instantaneous tripping element in the magnetic only breakers may account for their overheating and trip failure in the experiment.

  19. Second-harmonic generation with Bessel beams

    NASA Astrophysics Data System (ADS)

    Shatrovoy, Oleg

    We present the results of a numerical simulation tool for modeling the second-harmonic generation (SHG) interaction experienced by a diffracting beam. This code is used to study the simultaneous frequency and spatial profile conversion of a truncated Bessel beam that closely resembles a higher-order mode (HOM) of an optical fiber. SHG with Bessel beams has been investigated in the past and was determined have limited value because it is less efficient than SHG with a Gaussian beam in the undepleted pump regime. This thesis considers, for the first time to the best of our knowledge, whether most of the power from a Bessel-like beam could be converted into a second-harmonic beam (full depletion), as is the case with a Gaussian beam. We study this problem because using HOMs for fiber lasers and amplifiers allows reduced optical intensities, which mitigates nonlinearities, and is one possible way to increase the available output powers of fiber laser systems. The chief disadvantage of using HOM fiber amplifiers is the spatial profile of the output, but this can be transformed as part of the SHG interaction, most notably to a quasi-Gaussian profile when the phase mismatch meets the noncollinear criteria. We predict, based on numerical simulation, that noncollinear SHG (NC-SHG) can simultaneously perform highly efficient (90%) wavelength conversion from 1064 nm to 532 nm, as well as concurrent mode transformation from a truncated Bessel beam to a Gaussian-like beam (94% overlap with a Gaussian) at modest input powers (250 W, peak power or continuous-wave operation). These simulated results reveal two attractive features -- the feasibility of efficiently converting HOMs of fibers into Gaussian-like beams, and the ability to simultaneously perform frequency conversion. Combining the high powers that are possible with HOM fiber amplifiers with access to non-traditional wavelengths may offer significant advantages over the state of the art for many important applications

  20. Entropic Fluctuations in Thermally Driven Harmonic Networks

    NASA Astrophysics Data System (ADS)

    Jakšić, V.; Pillet, C.-A.; Shirikyan, A.

    2017-02-01

    We consider a general network of harmonic oscillators driven out of thermal equilibrium by coupling to several heat reservoirs at different temperatures. The action of the reservoirs is implemented by Langevin forces. Assuming the existence and uniqueness of the steady state of the resulting process, we construct a canonical entropy production functional S^t which satisfies the Gallavotti-Cohen fluctuation theorem. More precisely, we prove that there exists κ _c>1/2 such that the cumulant generating function of S^t has a large-time limit e(α ) which is finite on a closed interval [1/2-κ _c,1/2+κ _c], infinite on its complement and satisfies the Gallavotti-Cohen symmetry e(1-α )=e(α ) for all α in R. Moreover, we show that e(α ) is essentially smooth, i.e., that e'(α )→ ∓ ∞ as α → 1/2 ∓ κ _c. It follows from the Gärtner-Ellis theorem that S^t satisfies a global large deviation principle with a rate function I( s) obeying the Gallavotti-Cohen fluctuation relation I(-s)-I(s)=s for all sin R. We also consider perturbations of S^t by quadratic boundary terms and prove that they satisfy extended fluctuation relations, i.e., a global large deviation principle with a rate function that typically differs from I( s) outside a finite interval. This applies to various physically relevant functionals and, in particular, to the heat dissipation rate of the network. Our approach relies on the properties of the maximal solution of a one-parameter family of algebraic matrix Riccati equations. It turns out that the limiting cumulant generating functions of S^t and its perturbations can be computed in terms of spectral data of a Hamiltonian matrix depending on the harmonic potential of the network and the parameters of the Langevin reservoirs. This approach is well adapted to both analytical and numerical investigations.