Nuclear Scatter Research Articles

Nuclear norm-based two-dimensional discriminant locality preserving projection for face recognition

Two-dimensional discriminant locality preserving projection (2DDLPP) is an effective method for image feature extraction. However, original 2DDLPP is based solely on the Euclidean distance, which is sensitive to noises and illumination changes in images. To overcome this drawback, we propose a method named nuclear norm-based two-dimensional discriminant locality preserving projection (NN2DDLPP). In NN2DDLPP, two optimal neighbor graphs are first built. Then the nuclear norm-based between-class scatter and within-class scatter are defined. Finally, in order to obtain an optimal projection matrix, the ratio of between-class scatter to within-class scatter is maximized. Using nuclear norm metric and labeled information, NN2DDLPP can both efficiently extract the discriminative features and improve the robustness to illumination changes and noises. Experiments carried out on several different face image databases validate that NN2DDLPP is efficacious for face recognition and better than other related works.

Quasiparticle Diffusion in CRESST Light Detectors

CRESST-II is a direct dark matter experiment that uses scintillating calorimeters to detect WIMP-induced nuclear scatter processes. Heat and light signals are read out with tungsten transition edge sensors (TESs) that are optimized toward their sensitivity to non-thermal phonons. The usage of superconducting thin film structures (e.g., aluminum) serving as phonon collectors to increase the collection area for this signal component is an approach to improve the sensitivity of the TES. The performance of the phonon collectors depends on the material properties and the quality achieved in the production process. We optimized the size of the phonon collectors for the given quality of CRESST-II light detectors. The diffusion lengths measured in this work are $$\mathcal {O}$$ (1 mm) and show a strong correlation to the Residual Resistivity Ratio of the respective films. First tests of CRESST-II light detectors with larger as well as thicker phonon collectors individually show improvements in the measured pulse height of 30 %.

Comprehensive assessment of nuclear and cortical backscatter metrics derived from rotating Scheimpflug images

To quantify cataract in lens-backscatter metrics derived from Pentacam Scheimpflug photographs and determine the most predictive metrics for lens grading and visual performance measures. Large tertiary referral hospital in South Australia. Evaluation of diagnostic test or technology. In patients attending a cataract clinic between 2005 and 2008, standardized clinical assessments were performed and Scheimpflug photographs taken. Thirteen measures of cataract backscatter were drawn from the images of nuclear and cortical cataract, including new metrics for cortical cataract. The relationships between lens-scatter metrics, visual performance, and lens grades were determined with stepwise multiple linear regression. The study enrolled 342 eyes (177 patients). The Lens Opacities Classification System III (LOCS III) nuclear opalescence was best predicted by the average backscatter in the anterior half of the nucleus and the whole nucleus average (r(2) = 0.59). The LOCS III cortical grade was best predicted by the number of slices with significant cortical cataract (r(2) = 0.52), as was Pelli-Robson contrast sensitivity (r(2) = 0.16). Visual acuity was best predicted by the combined anterior half and whole nucleus averages (r(2) = 0.20). Pelli-Robson contrast sensitivity under glare was best predicted by a combination of the anterior half and whole nucleus averages and the calculated percentage of cortical cataract (r(2) = 0.16). Scheimpflug image-derived metrics of nuclear scatter were predictive of visual acuity and contrast sensitivity, whereas metrics of cortical cataract were predictive of visual performance under glare. Automated reporting of cataract severity from Scheimpflug images could be useful clinically and should include measurements of cortical cataract. Neither author has a financial or proprietary interest in any material or method mentioned.

Golden beam data for proton pencil-beam scanning

Proton, as well as other ion, beams applied by electro-magnetic deflection in pencil-beam scanning (PBS) are minimally perturbed and thus can be quantified a priori by their fundamental interactions in a medium. This a priori quantification permits an optimal reduction of characterizing measurements on a particular PBS delivery system. The combination of a priori quantification and measurements will then suffice to fully describe the physical interactions necessary for treatment planning purposes. We consider, for proton beams, these interactions and derive a ‘Golden’ beam data set. The Golden beam data set quantifies the pristine Bragg peak depth-dose distribution in terms of primary, multiple Coulomb scatter, and secondary, nuclear scatter, components. The set reduces the required measurements on a PBS delivery system to the measurement of energy spread and initial phase space as a function of energy. The depth doses are described in absolute units of Gy(RBE) mm2 Gp−1, where Gp equals 109 (giga) protons, thus providing a direct mapping from treatment planning parameters to integrated beam current. We used these Golden beam data on our PBS delivery systems and demonstrated that they yield absolute dosimetry well within clinical tolerance.

Quantitative Measurement of Apoptotic and Mitotic Nuclear Events Using Automated Classification of Bright Field and Nuclear Fluorescent Imagery with the ImageStream MultiSpecral Imaging Flow Cytometer

Both apoptotic and mitotic cells exhibit nuclear condensation which can be measured in a quantitative manner using a simple DNA dye and the ImageStream multispectral imaging flow cytometry. To distinguish apoptotic from mitotic cells additional morphological measurements such as textured brightfield imagery and increased texture and intensity of dark field scatter imagery may also be required. Distinguishing the sometimes minimal difference in level of nuclear condensation between apoptotic and mitotic cells in an automated manner can be problematic when applying only individual intensity and texture image analysis parameters. Here we present an automatic classifier which generates complex weighted combinations of intensity and texture features applied to multiple images of each cell to optimize distinction and quantitation of apoptotic and mitotic events in the same sample. Imagery from Ramos, Jurkat, and Colo205 cell lines were acquired on the ImageStream multispectral imaging flow cytometer after incubation with mechanistically distinct apoptosis inducing drugs (Camptothecin and Staurosporine) and staining with simple nuclear dyes. The accuracy of an automatic classifier which can measure the apoptotic index and mitotic index of samples based on brightfield, nuclear, and darkfield scatter imagery without the need for additional fluorescent labels using the IDEAS analytical software package is demonstrated.

γD-Crystallin–Associated Protein Aggregation and Lens Fiber Cell Denucleation

To understand the underlying molecular mechanism for a dominant cataract caused by a point mutation in the gammaD-crystallin gene. A dominant cataractous mouse line was identified from chemically induced mouse mutations by phenotypic screening with slit lamp examination. Genomewide linkage analysis and DNA sequencing were used to determine the causative gene mutation. Histology, immunohistochemistry, Western blotting, and in vitro transfection studies were used to characterize mutant lenses. Cataracts in mutant mice were caused by a point mutation in the gammaD-crystallin gene (gammaD-V76D). Intranuclear gamma-crystallin aggregates, incomplete denucleation, and decreased connexins were observed in mutant lens fiber cells. Mutant gammaD-V76D proteins became less soluble in the lens, and structural modeling suggested that the substituted aspartic acid residue (D) altered hydrogen bond formation and surface electrostatic potential of the protein. Unexpectedly, the formation of cold cataracts, which occurred in wild-type lenses at low temperature, was abolished in gammaD-V76D mutant lenses. In vitro transfection studies revealed that wild-type gammaD proteins were uniformly distributed in the cytosol and nucleus of transfected cells, whereas gammaD-V76D proteins formed cytosolic and nuclear aggregates. Mutant gammaD-V76D reduces protein solubility in the lens and forms substantial intranuclear aggregates that disrupt the denucleation process of inner lens fiber cells. Sustained fiber cell nuclei and nuclear remnants scatter light, whereas other downstream events, such as decreased connexins, presumably disrupt gap junction communication and lens homeostasis, further contributing to the cataract phenotype in mutant lenses. This work also suggests that gammaD-crystallin is one of the crucial components for the formation of cold cataracts in vivo.

Vacuolar cytoplasmic phase separation in cultured mammalian cells involves the microfilament network and reduces motional properties of intracellular water.

Hep-2, human epithelial carcinoma cells, and human foreskin fibroblasts (FF9 and FF13) were exposed to either an ultrafiltrate (< 50 kD) of human sera or the weak base, procaine hydrochloride, to induce reversible cytoplasmic vacuolization. The formation of vacuoles was shown not to be due to imbibition of medium. Ultrastructural details obtained from various stages of vacuole formation were compared. In both cases of induction vacuoles were irregular and often appeared membraneless, with little in the way of electron-dense content. They started to form in the perinuclear cytoplasm and progressed towards the periphery. Osmotic stress was not involved since mitochondria remained normal throughout a vacuolization episode. Vacuoles were often seen in close contact with filamentous structures, and this association remained detectable at late stages of the phenomenon. Fluorescent visualization of F-actin confirmed that the vacuoles were frequently bordered by microfilaments. No major metabolic impairment was apparent in vacuolized cells as judged by protein synthesis measurements, but nuclear fluorescence (DNA content) and forward light scatter (nuclear volume) by flow cytometric analysis suggested late S phase and G2 retardation. 1H-nmr relaxation measurements indicated intracellular water restricted in motional characteristics in vacuolized cells. The possibility of a restricted cytoplasmic phase separation as part of a transient adaptation response is raised, and a hypothesis to explain the findings is discussed.

Associations between lens features assessed in the Oxford Clinical Cataract Classification and Grading System

PURPOSE To study the associations between eleven lens features graded according to the Oxford Clinical Cataract Classification and Grading System (OCCCGS).METHOD 560 subjects taking part in the Melton Eye Study had their lenses graded according to the OCCCGS by one of two examiners. Associations between features were examined using log-linear models for categorised grades. Adjustment was made for age, sex and grader.RESULTS Within subjects, the two nuclear features, white nuclear scatter and brunescence, are closely related with one another, as are coronary flakes and focal-dots, but these two groupings are negatively associated. Cortical spoke, fibrefolds and waterclefts are all associated with one another and this group is positively associated with coronary flakes and focal-dots. Posterior subcapsular and anterior subcapsular opacity are associated with one another and with cortical spokes. A within-eye analysis gives similar results.CONCLUSION These associations may be important in defining cataract subtypes and in identifying minor features that indicate early cataract development.

Prevalence of lenticular abnormalities in a population-based study: Oxford clinical cataract grading in the Melton Eye Study

Purpose To describe the distribution of the 11 features assessed by the Oxford Clinical Cataract Classification and Grading System (OCCCGS) in a population-based study.Methods The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. Both lenses of 560 subjects were graded at the slit lamp using a decimalised version of the OCCCGS. Subject prevalences were estimated by logistic regression and the extent, when present, against normal errors regression.Results White nuclear scatter (WNS), brunescence, cortical spoke (cs), anterior subcapsular opacity (ASC), fibre folds (FF), waterclefts (WC) and perinuclear retro-dots all increased with age (p < 0.05). Posterior subcapsular opacity (PSC), vacuoles, focal dots (FD) and coronary flakes (CF) did not significantly increase with age. Subject prevalences of the features and the mean Oxford scores when present were: WNS (1.33), brunescence (0.88), CS 36% (0.34), PSC 11% (0.52), ASC 2% (0.53), FF 18% (0.53), WC 17% (0.29), retro-dots 11% (1.15), vacuoles 59% (0.43), FD 98% (1.79) and CF 39% (1.24). Significantly more common in women were both coronary flakes (p < 0.001) and waterclefts (p < 0.05).Conclusions These are the first data on the distribution of these minor lesions in a population-based study. Coronary flakes and waterclefts are more common in women.

Measured changes in cataract over six months: sensitivity of the Nidek EAS-1000.

Lens opacities in 98 eyes from 63 consecutive outpatients with cataract were recorded by both retroillumination and Scheimpflug slit methods by one operator. This was repeated at 26 +/- 1 weeks. Image analysis used the EAS-1000 software. Cortical and posterior subcapsular (PSC) cataracts were measured in retroillumination images as density more than 14 cct units below background density. Linear densitometry of white scattered light along the optical axis was measured for slit images by both peak density and mean density ('area under the curve'). Retroillumination images showed no discernible change over 6 months (the regression coefficient being as for the intersession reliability). Half of the Scheimpflug slit images could not be analysed because overlying cortical changes masked the more posterior parts of the lens. The other 49 eyes showed a significant increase in nuclear white scatter after 6 months, with greater degrees of change occurring in those eyes with the greatest amount of nuclear cataract initially. This is reflected by the decreased intraclass correlation coefficient (R = 0.42). The area of lens showing greatest change was the anterior fetal nucleus. The Nidek EAS-1000 is able to detect changes over a 6-month period in nuclear density but not in cortical or PSC cataract. The rate of progression of nuclear white scatter increases as the lens opacity becomes more dense. The ability to detect change in cataract over 6 months has implications for epidemiological studies and for trials of anti-cataract drugs.

The relationship between central nuclear scatter and perinuclear retrodots in the human crystalline lens.

Retrodots are common perinuclear features of age-related cataract. Clinical observation suggested that retrodots were associated with increased nuclear scatter. To test this hypothesis, retrospective data were analysed from 78 non-diabetic subjects (118 eyes), of at least 50 years of age, who had neither subscapsular nor axial spoke opacities. Retrodots were graded using the Oxford Clinical Cataract Classification and Grading system and central nuclear scatter was assessed by image analysis of Scheimpflug photographic negatives. Regression analysis in groups was performed according to the "intra-class correlation model" either considering retrodots as a graded feature (grades 0-5) or as a dichotomous variable (present or absent). After adjusting for age (treated as a co-variate), a highly significant association (P < 10(-6) was found between retrodots and increased nuclear scatter in each analysis. It is suggested that the co-existence of these two cataract types may reflect a common cataractogenic mechanism, possibly oxidative stress.

Changes in cell nuclei during S Phase: Progressive chromatin condensation and altered expression of the proliferation-associated nuclear proteins Ki-67, cyclin (PCNA), p105, and p34

Using multiparameter flow cytometry we have measured the nuclear DNA content of exponentially growing HL-60 cells in conjunction with protein content, nuclear forward light scatter, DNA in situ sensitivity to denaturation, DNA accessibility to 7-aminoactinomycin D (7-AMD), and content of the proliferation-associated proteins: cyclin (PCNA), p105, p34, and Ki-67. Multivariate analysis of the data made it possible to correlate changes in each parameter with the degree of cell advancement through S phase (amount of replicated DNA). A decrease of the protein/DNA ratio, lowered DNA accessibility to 7-AMD, increased sensitivity of DNA to denaturation, and increased ability of isolated nuclei to scatter light all paralleled cell progression through S phase. These changes indicate that during S phase chromatin progressively condenses and suggest that the condensation is associated with the efflux of nonhistone proteins from the nucleus. The increase in the content of the antigen detected by the Ki-67 antibody was observed to exceed the increase in DNA content during S phase and the rate of the Ki-67 DNA increase was higher during the second half of S phase. Thus, this protein appears to be primarily synthesized during S, especially late in S phase, and is degraded in G 1. The ratio of cyclin (PCNA)/DNA remained rather constant whereas the contents of p105 and p34 proteins, when expressed per unit of DNA, both decreased during S phase. The data indicate that significant changes in structure and composition of chromatin take place during S phase and suggest that the composition of chromatin associated with the nonreplicated DNA is different compared to chromatin associated with the newly replicated DNA.

Fluctuations and coherence in ultrarelativistic heavy-ion collisions

Fluctuations in transverse energy and multiplicity in ultrarelativistic heavy-ion collisions are a valuable probe of the collision dynamics. Analysis of recent CERN and BNL data on fluctuations in central collisions provides evidence that the nuclear constituents scatter and produce particles coherently.

Subpopulation analysis of drug‐induced cell‐cycle delay in human tumor cells using 90° light scatter

A mitotic cell subset has been identified with nuclear light scatter. Colcemid-treated T-47D human breast cancer cells were permeabilised, stained with ethidium bromide, and analysed by flow cytometry. Cells with G2M DNA content exhibited a unimodal distribution for DNA fluorescence and forward scatter, but two peaks were discernible with 90 degrees light scatter. A discrete low-scattering cell cluster could be distinguished from the G2 cell subset on two-dimensional contour plots of 90 degrees light scatter vs. DNA fluorescence; this cluster was reproduced by mitotic shake-off experiments and varied quantitatively with mitotic indices determined either by microscopy or by stathmokinetic cell-cycle analysis of DNA fluorescence. Cell sorting confirmed that the low-scattering cell cluster comprised predominantly metaphase and anaphase cells. Identification of mitotic cells with this one-step technique enables rapid analysis of drug-induced cell-cycle delay in cell populations with different rates of cell-cycle traverse. Hence, vincristine-induced cytostasis is shown to arise in part because of premitotic G2 arrest, whereas etoposide is shown to affect cycling cells with equal sensitivity in quiescent and activated cell populations. The use of light scatter to discriminate mitotic cells in this way facilitates analysis of drug-induced cell-cycle delay and supplements the information obtainable by conventional cell-cycle analysis.

A new method of measuring in vivo the lens transmittance, and study of lens scatter, fluorescence and transmittance.

We propose a new method to measure in vivo nuclear transmittance using scanning photometry, thus complementing its present application in measuring lens scatter and fluorescence. We compared our method of measuring the transmittance with a previously reported in vivo method and found an adequate correlation. We then measured the fluorescence, scatter and transmittance of lenses without cataract and those with as much as a mild yellowing. The three phenomena correlated with age. In addition, this study allowed a correlation of the three phenomena with each other, indicating that the loss of transmittance of the nucleus cannot be explained by its thickening alone but that changes in its composition must take place. Finally, a preliminary study on diabetics showed early onset of the process responsible for the increase in lens fluorescence. This process did not seem to be accelerated in diabetics in comparison with normals. The nuclear scatter appeared to increase more rapidly with age in nondiabetics as compared to diabetics. This preliminary study suggests mainly that scanning photometry can be used to study aging and pathologic changes in the lens.

The determination of the sign of the asymmetry parameter in λ0 decay from the scattering of the decay proton

A statistical method is presented whereby the information provided by a small number of nuclear scatters of λ0 decay protons can be used to determine the sign of the asymmetry parameter due to parity non-conservation in λ0 decay. As an example, the analysis is applied to twenty-one proton scatters of λ0 hyperons decaying in the Princeton multiplate cloud chamber. Because the asymmetry to be expected in each observed nuclear scatter is small, our data do not yield a statistically significant result. However, if each experimenter would follow a similar procedure with his data, it should be possible to combine results to determine the sign with a high degree of certainty.