Publications by authors named "A Meiri"

27 Publications

  • Page 1 of 1

Unmet communication needs and moral work in the disposition decision concerning surplus frozen embryos: The perspectives of IVF users.

Soc Sci Med 2021 Apr 26;274:113804. Epub 2021 Feb 26.

Sarah Racine IVF Unit, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, 6423906, Israel.

The disposition decision is a frequently unresolved issue for many IVF users with surplus frozen embryos (SFEs), and this study draws attention to their experiences and moral work, locating it in the Jewish-Israeli context that legally enables the donation of SFEs to research but prohibits donation to other infertile people. To explore the (mis)understandings and (mis)communication underlying IVF users' decisions concerning the fate of their SFEs, the records of 674 IVF users with SFEs stored for more than 5 years during 1996-2011 were analyzed, and 89 IVF users with different disposition decisions were recruited for semi-structured interviews. With an average of 5.1 SFEs, after an average of 8 years of storage, no response to a written request for a disposition decision came from 60% (n = 404) of IVF users with SFEs. Payment for storage and defrosting were the two most frequent choices (13%, n = 89 and 89, respectively) followed by donation to research and transfer (7%, n = 47 and 45, respectively). Three themes emerged from the interviews: misunderstanding the consequences of not returning the disposition form, communication gaps regarding donation to research, and the unmet wish to donate embryos to infertile people. We conclude by discussing the experiences and views of IVF users as reflecting the implications of the liminality and boundary-work surrounding the frozen embryo as a moral work object, and their consequences for policy recommendations.
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http://dx.doi.org/10.1016/j.socscimed.2021.113804DOI Listing
April 2021

MR Elastography demonstrates reduced white matter shear stiffness in early-onset hydrocephalus.

Neuroimage Clin 2021 Feb 2;30:102579. Epub 2021 Feb 2.

Montefiore Medical Center, Department of Neurosurgery, Bronx, NY, USA.

Introduction: Hydrocephalus that develops early in life is often accompanied by developmental delays, headaches and other neurological deficits, which may be associated with changes in brain shear stiffness. However, noninvasive approaches to measuring stiffness are limited. Magnetic Resonance Elastography (MRE) of the brain is a relatively new noninvasive imaging method that provides quantitative measures of brain tissue stiffness. Herein, we aimed to use MRE to assess brain stiffness in hydrocephalus patients compared to healthy controls, and to assess its associations with ventricular size, as well as demographic, shunt-related and clinical outcome measures.

Methods: MRE was collected at two imaging sites in 39 hydrocephalus patients and 33 healthy controls, along with demographic, shunt-related, and clinical outcome measures including headache and quality of life indices. Brain stiffness was quantified for whole brain, global white matter (WM), and lobar WM stiffness. Group differences in brain stiffness between patients and controls were compared using two-sample t-tests and multivariable linear regression to adjust for age, sex, and ventricular volume. Among patients, multivariable linear or logistic regression was used to assess which factors (age, sex, ventricular volume, age at first shunt, number of shunt revisions) were associated with brain stiffness and whether brain stiffness predicts clinical outcomes (quality of life, headache and depression).

Results: Brain stiffness was significantly reduced in patients compared to controls, both unadjusted (p ≤ 0.002) and adjusted (p ≤ 0.03) for covariates. Among hydrocephalic patients, lower stiffness was associated with older age in temporal and parietal WM and whole brain (WB) (beta (SE): -7.6 (2.5), p = 0.004; -9.5 (2.2), p = 0.0002; -3.7 (1.8), p = 0.046), being female in global and frontal WM and WB (beta (SE): -75.6 (25.5), p = 0.01; -66.0 (32.4), p = 0.05; -73.2 (25.3), p = 0.01), larger ventricular volume in global, and occipital WM (beta (SE): -11.5 (3.4), p = 0.002; -18.9 (5.4), p = 0.0014). Lower brain stiffness also predicted worse quality of life and a higher likelihood of depression, controlling for all other factors.

Conclusions: Brain stiffness is reduced in hydrocephalus patients compared to healthy controls, and is associated with clinically-relevant functional outcome measures. MRE may emerge as a clinically-relevant biomarker to assess the neuropathological effects of hydrocephalus and shunting, and may be useful in evaluating the effects of therapeutic alternatives, or as a supplement, of shunting.
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http://dx.doi.org/10.1016/j.nicl.2021.102579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7905205PMC
February 2021

Inaccurate Estimates of Negotiated Reimbursement Prices for Insulin-Reply.

JAMA Intern Med 2021 Jan;181(1):141-142

Harvard Pilgrim Health Care Institute, Department of Population Medicine, Harvard Medical School, Boston, Massachusetts.

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http://dx.doi.org/10.1001/jamainternmed.2020.5047DOI Listing
January 2021

Trends in Insulin Out-of-Pocket Costs and Reimbursement Price Among US Patients With Private Health Insurance, 2006-2017.

JAMA Intern Med 2020 07;180(7):1010-1012

Harvard Pilgrim Health Care Institute, Department of Population Medicine, Harvard Medical School, Boston, Massachusetts.

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http://dx.doi.org/10.1001/jamainternmed.2020.1302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7265120PMC
July 2020

Characterization of the interactions between Codanin-1 and C15Orf41, two proteins implicated in congenital dyserythropoietic anemia type I disease.

BMC Mol Cell Biol 2020 Mar 23;21(1):18. Epub 2020 Mar 23.

The Mina and Everard Goodman faculty of life sciences Bar-Ilan University, 52900, Ramat-Gan, Israel.

Background: Congenital dyserythropoietic anemia type I (CDA I), is an autosomal recessive disease with macrocytic anemia in which erythroid precursors in the bone marrow exhibit pathognomonic abnormalities including spongy heterochromatin and chromatin bridges. We have shown previously that the gene mutated in CDA I encodes Codanin-1, a ubiquitously expressed and evolutionarily conserved large protein. Recently, an additional etiologic factor for CDA I was reported, C15Orf41, a predicted nuclease. Mutations in both CDAN1 and C15Orf41 genes results in very similar erythroid phenotype. However, the possible relationships between these two etiologic factors is not clear.

Results: We demonstrate here that Codanin-1 and C15Orf41 bind to each other, and that Codanin-1 stabilizes C15Orf41. C15Orf41 protein is mainly nuclear and Codanin-1 overexpression shifts it to the cytoplasm. Phylogenetic analyses demonstrated that even though Codanin-1 is an essential protein in mammals, it was lost from several diverse and unrelated animal taxa. Interestingly, C15Orf41 was eliminated in the exact same animal taxa. This is an extreme case of the Phylogenetic Profiling phenomenon, which strongly suggests common pathways for these two proteins. Lastly, as the 3D structure is more conserved through evolution than the protein sequence, we have used the Phyre2 alignment program to find structurally homologous proteins. We found that Codanin-1 is highly similar to CNOT1, a conserved protein which serves as a scaffold for proteins involved in mRNA stability and transcriptional control.

Conclusions: The physical interaction and the stabilization of C15Orf41 by Codanin-1, combined with the phylogenetic co-existence and co-loss of these two proteins during evolution, suggest that the major function of the presumptive scaffold protein, Codanin-1, is to regulate C15Orf41 activities. The similarity between Codanin-1 and CNOT1 suggest that Codanin-1 is involved in RNA metabolism and activity, and opens up a new avenue for the study of the molecular pathways affected in CDAI.
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http://dx.doi.org/10.1186/s12860-020-00258-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7092493PMC
March 2020

Imaging of nanoparticle dynamics in live and apoptotic cells using temporally-modulated polarization.

Sci Rep 2019 02 7;9(1):1650. Epub 2019 Feb 7.

Faculty of Engineering and the Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 5290002, Israel.

Gold nanoparticles are widely exploited in phototherapy. Owing to their biocompatibility and their strong visible-light surface plasmonic resonance, these particles also serve as contrast agents for cell image enhancement and super-resolved imaging. Yet, their optical signal is still insufficiently strong for many important real-life applications. Also, the differentiation between adjacent nanoparticles is usually limited by the optical resolution and the orientations of non-spherical particles are unknown. These limitations hamper the progress in cell research by direct optical microscopy and narrow the range of phototherapy applications. Here we demonstrate exploiting the optical anisotropy of non-spherical nanoparticles to achieve super-resolution in live cell imaging and to resolve the intracellular nanoparticle orientations. In particular, by modulating the light polarization and taking advantage of the polarization-dependence of gold nanorod optical properties, we realize the 'lock-in amplification', widely-used in electronic engineering, to achieve image enhancement in live cells and in cells that undergo apoptotic changes.
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http://dx.doi.org/10.1038/s41598-018-38375-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367359PMC
February 2019

Is There a Benefit to Culturing Intra-Uterine Devices in Pelvic Inflammatory Disease?

Gynecol Obstet Invest 2019 25;84(1):20-26. Epub 2018 Jul 25.

Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel-Aviv Medical Center, Affiliated to the Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.

Aims: The study aimed to compare the clinical course and disease severity between culture positive and culture negative patients with intra-uterine devices (IUD)-associated pelvic inflammatory disease (PID).

Methods: A retrospective study of all IUD-associated PID patients admitted to tertiary medical center between 2010 and 2015. All patients received standard empiric antibiotic therapy upon admission. The study cohort was divided into 2: patients with culture positive IUDs and patients with negative cultures. Electronic medical records and culture results were analyzed from the time of admission.

Results: During the study period, 480 hospitalized patients were diagnosed with PID. Of these, 94 patients had IUD-associated PID, 59 with positive cultures and 35 with negative cultures. While fever was more common in the latter (p = 0.01), no significant differences were found in disease severity in patient outcomes (i.e., length of stay, rates of invasive treatment, and total abdominal hysterectomies). In a sub-analysis of patients with IUD cultures of established PID pathogens only, there were no differences in disease severity and outcome in patients with antibiotic susceptible or resistant strains.

Conclusions: IUD removal for culture in PID patients is probably unnecessary. Alteration of treatment according to the culture results may have little impact on disease course and outcome.
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http://dx.doi.org/10.1159/000490666DOI Listing
March 2019

Complicated Clinical Course and Poor Reproductive Outcomes of Women with Tubo-Ovarian Abscess after Fertility Treatments.

J Minim Invasive Gynecol 2019 01 8;26(1):162-168. Epub 2018 Jun 8.

Lis Maternity Hospital, Department of Obstetrics and Gynecology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. Electronic address:

Study Objective: To assess the clinical course and surgical and fertility outcomes of patients diagnosed with tubo-ovarian abscess (TOA) after fertility treatment.

Design: Parallel case series over 10 consecutive years (Canadian Task Force classification II-2).

Setting: Tel Aviv Sourasky Medical Center, a tertiary university-affiliated hospital.

Patients: Thirty-seven women who were diagnosed with TOA after fertility treatments (in vitro fertilization and intrauterine insemination) were compared with 313 women who were diagnosed with TOA not associated with fertility treatments during the same time period.

Intervention: Medical records search, chart review, and phone survey were used to assess clinical course and surgical and reproductive outcomes.

Measurements And Main Results: Women with TOA after fertility treatments had significantly higher inflammatory markers upon admission compared with the nonfertility treatment group (mean white blood cell count, 16.1 × 1000/mm [standard deviation [SD], ±4.3] vs 13.8 × 1000/mm [SD, ±6.3], p = .001, respectively; and mean C-reactive protein, 149 mg/L [SD, ±78.3] vs 78.2 mg/L [SD, ±68.5], p = .001, respectively). In addition, TOA after fertility treatments was associated with a significantly higher surgical intervention rate and a more complicated clinical course, as evidenced by a shorter time interval from admission to surgery (2.1 days vs 3.2 days, p = .01), higher rates of antibiotic failure, higher conversion rate from laparoscopy to laparotomy (14.2% vs 3.2%, p = .005), increased perioperative complications rate (25.0% vs 3.8%, p = .0001), and a longer hospitalization stay (7.2 days vs 4.8 days, p = .01). Clinical pregnancy rate per cycle in women with TOA after fertility treatments was 9%, and 1 case of live birth was recorded.

Conclusions: Our data indicate that TOA after fertility treatment has a substantial effect on the clinical course and surgical outcome. Prophylactic antibiotic treatment before ovum retrieval and deferral of embryo transfer should be considered in patients at risk of infection.
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http://dx.doi.org/10.1016/j.jmig.2018.06.004DOI Listing
January 2019

Diffusion tensor imaging and ventricle volume quantification in patients with chronic shunt-treated hydrocephalus: a matched case-control study.

J Neurosurg 2018 12;129(6):1611-1622

1Department of Radiology, Gruss Magnetic Resonance Research Center, and.

OBJECTIVEThe object of this study was to use diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) to characterize the long-term effects of hydrocephalus and shunting on white matter integrity and to investigate the relationship of ventricular size and alterations in white matter integrity with headache and quality-of-life outcome measures.METHODSPatients with shunt-treated hydrocephalus and age- and sex-matched healthy controls were recruited into the study and underwent anatomical and DTI imaging on a 3-T MRI scanner. All patients were clinically stable, had undergone CSF shunt placement before 2 years of age, and had a documented history of complaints of headaches. Outcome was scored based on the Headache Disability Inventory and the Hydrocephalus Outcome Questionnaire. Fractional anisotropy (FA) and other DTI-based measures (axial, radial, and mean diffusivity; AD, RD, and MD, respectively) were extracted in the corpus callosum and internal capsule with manual region-of-interest delineation and in other regions with TBSS. Paired t-tests, corrected with a 5% false discovery rate, were used to identify regions with significant differences between patients and controls. Within the patient group, linear regression models were used to investigate the relationship between FA or ventricular volume and outcome, as well as the effect of shunt-related covariates.RESULTSTwenty-one hydrocephalus patients and 21 matched controls completed the study, and their data were used in the final analysis. The authors found significantly lower FA for patients than for controls in 20 of the 48 regions, mostly posterior white matter structures, in periventricular as well as more distal tracts. Of these 20 regions, 17 demonstrated increased RD, while only 5 showed increased MD and 3 showed decreased AD. No areas of increased FA were observed. Higher FA in specific periventricular white matter tracts, tending toward FA in controls, was associated with increased ventricular size, as well as improved clinical outcome.CONCLUSIONSThe study shows that TBSS-based DTI is a sensitive technique for elucidating changes in white matter structures due to hydrocephalus and chronic CSF shunting and provides preliminary evidence that DTI may be a valuable tool for tailoring shunt procedures to monitor ventricular size following shunting and achieve optimal outcome, as well as for guiding the development of alternate therapies for hydrocephalus.
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http://dx.doi.org/10.3171/2017.6.JNS162784DOI Listing
December 2018

Interference based localization of single emitters.

Opt Express 2017 Jul;25(15):17174-17191

The ability to localize precisely a single optical emitter is important for particle tracking applications and super resolution microscopy. It is known that for a traditional microscope the ability to localize such an emitter is limited by the photon count. Here we analyze the ability to improve such localization by imposing interference fringes. We show here that a simple grating interferometer can introduce such improvement in certain circumstances and analyze what is required to increase the localization precision further.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5557332PMC
http://dx.doi.org/10.1364/OE.25.017174DOI Listing
July 2017

Phase retrieval deblurring for imaging of dense object within a low scattering soft biological tissue.

J Biomed Opt 2016 09;21(9):96008

Bar Ilan University, Faculty of Engineering, Ramat Gan 5290002, Israel.

Tissues are characterized by a strong scattering of visible optical radiation, which prevents one from achieving deep-tissue imaging. We propose a computational imaging technique for the inference of specific macroscopic, spatial phase distribution features of the scattering media. The spatial phase distribution is reconstructed from several defocused intensity images. We empirically demonstrate the method by reconstructing the location of two fibula chicken bones, embedded within chicken breast tissue. The suggested technique is safe, using visible laser illumination, and noninvasive. It is also cost-effective since a simple optical system is used and the images are acquired using a conventional camera, and it does not require interferometric detection as well as direct access to the object in absence of the layer.
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http://dx.doi.org/10.1117/1.JBO.21.9.096008DOI Listing
September 2016

K-factor image deshadowing for three-dimensional fluorescence microscopy.

Sci Rep 2015 Sep 3;5:13724. Epub 2015 Sep 3.

Faculty of Engineering, Bar-Ilan University, Ramat-Gan 52900, Israel.

The ability to track single fluorescent particles within a three dimensional (3D) cellular environment can provide valuable insights into cellular processes. In this paper, we present a modified nonlinear image decomposition technique called K-factor that reshapes the 3D point spread function (PSF) of an XYZ image stack into a narrow Gaussian profile. The method increases localization accuracy by ~60% with compare to regular Gaussian fitting, and improves minimal resolvable distance between overlapping PSFs by ~50%. The algorithm was tested both on simulated data and experimentally.
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http://dx.doi.org/10.1038/srep13724DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558540PMC
September 2015

Cellular superresolved imaging of multiple markers using temporally flickering nanoparticles.

Sci Rep 2015 May 28;5:10965. Epub 2015 May 28.

1] Faculty of Engineering, Bar Ilan University, Ramat-Gan 5290002, Israel [2] The Bar-Ilan Institute of Nanotechnology &Advanced Materials, Bar Ilan University, Ramat-Gan 5290002, Israel.

In this paper we present a technique aimed for simultaneous detection of multiple types of gold nanoparticles (GNPs) within a biological sample, using lock-in detection. We image the sample using a number of modulated laser beams that correspond to the number of GNP species that label a given sample. The final image where the GNPs are spatially separated is obtained computationally. The proposed method enables the simultaneous superresolved imaging of different areas of interest within biological sample and also the spatial separation of GNPs at sub-diffraction distances, making it a useful tool in the study of intracellular trafficking pathways in living cells.
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http://dx.doi.org/10.1038/srep10965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4447069PMC
May 2015

Increased localization precision by interference fringe analysis.

Nanoscale 2015 Jun;7(23):10430-7

Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA.

We report a novel optical single-emitter-localization methodology that uses the phase induced by path length differences in a Mach-Zehnder interferometer to improve localization precision. Using information theory, we demonstrate that the localization capability of a modified Fourier domain signal generated by photon interference enables a more precise localization compared to a standard Gaussian intensity distribution of the corresponding point-spread function. The calculations were verified by numerical simulations and an exemplary experiment, where the centers of metal nanoparticles were localized to a precision of 3 nm.
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http://dx.doi.org/10.1039/c5nr01927cDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827330PMC
June 2015

Superresolved labeling nanoscopy based on temporally flickering nanoparticles and the K-factor image deshadowing.

Biomed Opt Express 2015 Apr 12;6(4):1262-72. Epub 2015 Mar 12.

Faculty of Engineering, Bar Ilan University, Ramat-Gan 5290002, Israel.

Localization microscopy provides valuable insights into cellular structures and is a rapidly developing field. The precision is mainly limited by additive noise and the requirement for single molecule imaging that dictates a low density of activated emitters in the field of view. In this paper we present a technique aimed for noise reduction and improved localization accuracy. The method has two steps; the first is the imaging of gold nanoparticles that labels targets of interest inside biological cells using a lock-in technique that enables the separation of the signal from the wide spread spectral noise. The second step is the application of the K-factor nonlinear image decomposition algorithm on the obtained image, which improves the localization accuracy that can reach 5nm and enables the localization of overlapping particles at minimal distances that are closer by 65% than conventional methods.
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http://dx.doi.org/10.1364/BOE.6.001262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4399665PMC
April 2015

Cellular imaging using temporally flickering nanoparticles.

Sci Rep 2015 Feb 4;5:8244. Epub 2015 Feb 4.

1] Faculty of Engineering, Bar Ilan University, Ramat-Gan 5290002, Israel [2] The Bar-Ilan Institute of Nanotechnology &Advanced Materials, Bar Ilan University, Ramat-Gan 5290002, Israel.

Utilizing the surface plasmon resonance effect in gold nanoparticles enables their use as contrast agents in a variety of applications for compound cellular imaging. However, most techniques suffer from poor signal to noise ratio (SNR) statistics due to high shot noise that is associated with low photon count in addition to high background noise. We demonstrate an effective way to improve the SNR, in particular when the inspected signal is indistinguishable in the given noisy environment. We excite the temporal flickering of the scattered light from gold nanoparticle that labels a biological sample. By preforming temporal spectral analysis of the received spatial image and by inspecting the proper spectral component corresponding to the modulation frequency, we separate the signal from the wide spread spectral noise (lock-in amplification).
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http://dx.doi.org/10.1038/srep08244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4316156PMC
February 2015

Fast wide-field photothermal and quantitative phase cell imaging with optical lock-in detection.

Biomed Opt Express 2014 Aug 8;5(8):2517-25. Epub 2014 Jul 8.

Department of Biomedical Engineering and Fitzpatrick Institute for Photonics, Duke University, Durham NC 27708, USA.

We present a fast, wide-field holography system for detecting photothermally excited gold nanospheres with combined quantitative phase imaging. An interferometric photothermal optical lock-in approach (POLI) is shown to improve SNR for detecting nanoparticles (NPs) on multiple substrates, including a monolayer of NPs on a silanized coverslip, and NPs bound to live cells. Furthermore, the set up allowed for co-registered quantitative phase imaging (QPI) to be acquired in an off-axis holographic set-up. An SNR of 103 was obtained for NP-tagging of epidermal growth factor receptor (EGFR) in live cells with a 3 second acquisition, while an SNR of 47 was seen for 20 ms acquisition. An analysis of improvements in SNR due to averaging multiple frames is presented, which suggest that residual photothermal signal can be a limiting factor. The combination of techniques allows for high resolution imaging of cell structure via QPI with the ability to identify receptor expression via POLI.
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http://dx.doi.org/10.1364/BOE.5.002517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132985PMC
August 2014

Improved localization accuracy in stochastic super-resolution fluorescence microscopy by K-factor image deshadowing.

Biomed Opt Express 2013 Dec 16;5(1):244-58. Epub 2013 Dec 16.

Faculty of Engineering, Bar-Ilan University, Ramat-Gan 52900, Israel.

Localization of a single fluorescent particle with sub-diffraction-limit accuracy is a key merit in localization microscopy. Existing methods such as photoactivated localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) achieve localization accuracies of single emitters that can reach an order of magnitude lower than the conventional resolving capabilities of optical microscopy. However, these techniques require a sparse distribution of simultaneously activated fluorophores in the field of view, resulting in larger time needed for the construction of the full image. In this paper we present the use of a nonlinear image decomposition algorithm termed K-factor, which reduces an image into a nonlinear set of contrast-ordered decompositions whose joint product reassembles the original image. The K-factor technique, when implemented on raw data prior to localization, can improve the localization accuracy of standard existing methods, and also enable the localization of overlapping particles, allowing the use of increased fluorophore activation density, and thereby increased data collection speed. Numerical simulations of fluorescence data with random probe positions, and especially at high densities of activated fluorophores, demonstrate an improvement of up to 85% in the localization precision compared to single fitting techniques. Implementing the proposed concept on experimental data of cellular structures yielded a 37% improvement in resolution for the same super-resolution image acquisition time, and a decrease of 42% in the collection time of super-resolution data with the same resolution.
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http://dx.doi.org/10.1364/BOE.5.000244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3891336PMC
December 2013

Comparative review of interferometric detection of plasmonic nanoparticles.

Biomed Opt Express 2013 16;4(10):2166-78. Epub 2013 Sep 16.

Department of Biomedical Engineering and Fitzpatrick Institute for Photonics, Duke University, Durham NC 27708, USA.

Noble metal nanoparticles exhibit enhanced scattering and absorption at specific wavelengths due to a localized surface plamson resonance. This unique property can be exploited to enable the use of plasmonic nanoparticles as contrast agents in optical imaging. A range of optical techniques have been developed to detect nanoparticles in order to implement imaging schemes. Here we review several different approaches for using optical interferometry to detect the presence and concentration of nanoparticles. The strengths and weaknesses of the various approaches are discussed and quantitative comparisons of the achievable signal to noise ratios are presented. The benefits of each approach are outlined as they relate to specific application goals.
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http://dx.doi.org/10.1364/BOE.4.002166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799674PMC
October 2013

Photonic XOR with inherent loss compensation mechanism for memory cell implementation in a standard nanoscale very large-scale integrated fabrication process.

Opt Lett 2013 May;38(9):1473-5

Faculty of Engineering, Bar-Ilan University, Ramat-Gan 52900, Israel.

A multilayer photonic XOR gate is presented. The XOR is implemented by the interconnect layers of a microelectronic chip and is suitable for fabrication in a standard VLSI fabrication process. The proposed device features an inherent insertion loss compensation mechanism by utilization of nanometric holes, making it possible to implement an optic memory cell without the need of additional complex compensation devices. The structure of such a memory cell, implemented by utilization of two proposed XOR gates, configured to perform the NOT function, is shown. The unique structure of the proposed device allows us to significantly reduce sensitivity to process variations and therefore makes it possible to utilize the memory cell in state-of-the-art nanoscale processes. The proposed memory can be integrated with conventional electronics on the same VLSI chip.
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http://dx.doi.org/10.1364/OL.38.001473DOI Listing
May 2013

Resource Utilization Reduction for Evaluation of Chest Pain in Pediatrics Using a Novel Standardized Clinical Assessment and Management Plan (SCAMP).

J Am Heart Assoc 2012 Apr 24;1(2). Epub 2012 Apr 24.

Department of Cardiology, Children's Hospital Boston and the Department of Pediatrics, Harvard Medical School Boston, MA.

Background: Chest pain is a common reason for referral to pediatric cardiologists. Although pediatric chest pain is rarely attributable to serious cardiac pathology, extensive and costly evaluation is often performed. We have implemented a standardized approach to pediatric chest pain in our pediatric cardiology clinics as part of a broader quality improvement initiative termed Standardized Clinical Assessment and Management Plans (SCAMPs). In this study, we evaluate the impact of a SCAMP for chest pain on practice variation and resource utilization.

Methods And Results: We compared demographic variables, clinical characteristics, and cardiac testing in a historical cohort (n=406) of patients presenting to our outpatient division for initial evaluation of chest pain in the most recent pre-SCAMP calendar year (2009) to patients enrolled in the chest pain SCAMP (n=364). Demographic variables including age at presentation, sex, and clinical characteristics were similar between groups. Adherence to the SCAMP algorithm for echocardiography was 84%. Practice variation decreased significantly after implementation of the SCAMP (P<0.001). The number of exercise stress tests obtained was significantly lower in the SCAMP-enrolled patients compared with the historic cohort (∼3% of patients versus 29%, respectively; P<0.001). Similarly, there was a 66% decrease in utilization of Holter monitors and 75% decrease in the use of long-term event monitors after implementation of the chest pain SCAMP (P=0.003 and P<0.001, respectively). The number of echocardiograms obtained was similar between groups.

Conclusions: Implementation of a SCAMP for evaluation of pediatric chest pain has lead to a decrease in practice variation and resource utilization. (J Am Heart Assoc. 2012;1:jah3-e000349 doi: 10.1161/JAHA.111.000349.).
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http://dx.doi.org/10.1161/JAHA.111.000349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3487367PMC
April 2012

Intercoupling surface plasmon resonance and diffusion reflection measurements for real-time cancer detection.

J Biophotonics 2013 Feb 28;6(2):188-96. Epub 2012 Mar 28.

Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, 52900, Israel.

Spatial diffusion reflection (DR) measurements of gold nanorods (GNR) were recently suggested as a simple and highly sensitive non-invasive and non-ionizing method for real-time cancer detection. In this paper we demonstrate that wavelength dependent DR measurements enable the spectral red-shift observation of highly concentrated GNR. By conjugating targeting moieties to the GNR, large density of GNR can specifically home onto cancer cells. The inter-particle plasmon resonance pattern of the highly concentrated GNR leads to an extension and a red-shift (Δλ) in the absorption spectrum of the concentrated GNR. Dark-field microscopy was used in order to measure the expected Δλ in different GNR concentrations in vitro. Double-wavelength DR measurements of tissue-like phantoms and tumor bearing mice containing different GNR concentrations are presented. We show that the DR profile of the highly concentrated GNR directly correlate with the spectral extension and red-shift. This presented work suggests that wavelength dependent DR method can serve as a promising tool for real-time superficial tumor detection.
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http://dx.doi.org/10.1002/jbio.201200016DOI Listing
February 2013

Sub-micron particle based structures as reconfigurable photonic devices controllable by external photonic and magnetic fields.

Sensors (Basel) 2011 2;11(3):2740-50. Epub 2011 Mar 2.

School of Engineering, Bar-Ilan University, Ramat Gan 52900, Israel.

In this paper we present the configurations of two nanometer scale structures--one of them optically controllable and the second one magnetically controllable. The first involves an array of nanoparticles that are made up of two layers (i.e., Au on top of a Si layer). The device may exhibits a wide range of plasmonic resonance according to external photonic radiation. The second type of device involves the usage of sub micron superparamagnetic particles located on a suitable structuring grid, that according to the angle of the external magnetic field allows control of the length of the structuring grid and therefore control the diffraction order of each wavelength.
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http://dx.doi.org/10.3390/s110302740DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3231588PMC
June 2012

Growth and Deposition of Inorganic Nutrient Elements in Developing Leaves of Zea mays L.

Plant Physiol 1992 Jul;99(3):972-8

Department of Land, Air and Water Resources, University of California, Davis, California 95616.

Spatial distributions of growth and of the concentration of some inorganic nutrient elements were analyzed in developing leaves of maize (Zea mays L.). Growth was analyzed by pinprick experiments with numerical analysis to characterize fields of velocity and relative elemental elongation rate. Inductively coupled plasma and atomic emission spectroscopy were used to measure nutrients extracted from segments of leaf tissue collected by position. Leaves 7 and 8, both elongating 3 millimeters per hour had maximum relative elemental growth rates of 0.06 to 0.08 millimeters per hour with maximum rates 20 to 50 millimeters from the node and cessation of growth by 90 millimeters from the node. Spatial distribution of dry weight density revealed that the rate of biomass deposition was maximum in the most rapidly expanding region and continued beyond the elongation zone. The nutrient elements K, Cl, Ca, Mg, and P showed different distribution patterns of ion density (on a dry weight basis). K and Cl had minimal density in the leaf tips; K density was maximum in the growing region, whereas Cl density was maximum at the region of growth cessation. Ca, Mg, and P had relatively high densities at the base of the elongation zone near the node and also in the tip regions. Near the node, P and Mg densities were higher in the young, growing leaves, whereas Ca density near the node was higher in older leaves that had completed elongation. Deposition rates of all nutrients were greatest in the region of maximum elongation rate.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1080572PMC
http://dx.doi.org/10.1104/pp.99.3.972DOI Listing
July 1992

Isoosmotic regulation of cotton and peanut at saline concentrations of k and na.

Plant Physiol 1988 Aug;87(4):911-6

Institute of Soils and Water, Agricultural Research Organization, P.O.B. 6 Bet Dagan, Israel 50-250.

Peanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum) plants were grown for 4 weeks in saline, isoosmotic rooting substrates with different proportions of K and Na. Isoosmotic media did not affect growth (except at the highest external K concentrations) or estimates of intracellular osmotic pressure in expanding leaves (i.e. osmotic pressure of leaf sap and intracellular osmotic pressure as calculated from pressure-volume curves). In expanded leaves, an increase in the proportion of external K increased sap osmotic pressure. The sum of [K+Na+Cl] in the sap of expanding and expanded leaves accounted for the effect of isoosmotic media on the concentration of osmolytes with high electrical conductance, so the difference between sap osmotic pressure and [K+Na+Cl] accounted for the concetration of osmolytes with low conductance. In expanding leaves, an increase in the proportion of external K increased [K+Na+Cl] and decreased the concentration of osmolytes with low conductance. In expanded leaves, an increase in the proportion of external K increased [K+Na+Cl] to approximately the same extent as sap osmotic pressure. Isoosmotic regulation was apparent in expanding leaves but not evident in expanded leaves. This suggests a turgor homeostat which can influence the concentration of organic solutes in expanding leaves but cannot control the import of inorganic solutes from a rooting medium nor the total production of organic solutes in plants with a low sink:source ratio.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1054868PMC
http://dx.doi.org/10.1104/pp.87.4.911DOI Listing
August 1988

The effects of exposure duration and luminance on the 3-dot hyperacuity task.

Vision Res 1984 ;24(8):871-4

The 3-dot hyperacuity task was given to two subjects under three experimental paradigms: constant luminance, constant energy and constant duration. Hyperacuity was obtained under conditions (3 dots, 2 msec exposure) which rule out any significant temporal or spatial averaging. There was a clear threshold decrease in the constant luminance paradigm as exposure duration increased, no significant variations in threshold with the constant energy paradigm, as exposure duration varied and a U-shaped function in the constant exposure duration paradigm as luminance varied. It is concluded that what limits performance, at least for short exposure durations, is the total energy of the stimulus. The implications of the present results to the static and dynamic approaches to hyperacuity are discussed.
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http://dx.doi.org/10.1016/0042-6989(84)90160-3DOI Listing
October 1984