Search

AMoRE is an international project to search for the neutrinoless double beta decay of $^{100}$Mo using a detection technology consisting of magnetic microcalorimeters (MMCs) and molybdenum-based scintillating crystals. Data collection has begun for the current AMORE-I phase of the project, an upgrade from the previous pilot phase. AMoRE-I employs thirteen $^\mathrm{48depl.}$Ca$^{100}$MoO$_4$ crystals and five Li$_2$$^{100}$MoO$_4$ crystals for a total crystal mass of 6.2 kg. Each detector module contains a scintillating crystal with two MMC channels for heat and light detection. We report the present status of the experiment and the performance of the detector modules., Comment: 8 pages, 4 figures, published in Journal of Low Temperature Physics (2022)

Description, Dark matter interpretations of the DAMA signals are excluded by COSINE-100 with the same NaI(Tl) target for various models., We present new constraints on dark matter interactions using 1.7 years of COSINE-100 data. The COSINE-100 experiment, consisting of 106 kg of tallium-doped sodium iodide [NaI(Tl)] target material, is aimed to test DAMA’s claim of dark matter observation using the same NaI(Tl) detectors. Improved event selection requirements, a more precise understanding of the detector background, and the use of a larger dataset considerably enhance the COSINE-100 sensitivity for dark matter detection. No signal consistent with the dark matter interaction is identified and rules out model-dependent dark matter interpretations of the DAMA signals in the specific context of standard halo model with the same NaI(Tl) target for various interaction hypotheses.

Silicon photomultipliers are regarded as a very promising technology for next-generation, cutting-edge detectors for low-background experiments in particle physics. This work presents systematic reflectivity studies of Silicon Photomultipliers (SiPM) and other samples in liquid xenon at vacuum ultraviolet (VUV) wavelengths. A dedicated setup at the University of M\"unster has been used that allows to acquire angle-resolved reflection measurements of various samples immersed in liquid xenon with 0.45{\deg} angular resolution. Four samples are investigated in this work: one Hamamatsu VUV4 SiPM, one FBK VUV-HD SiPM, one FBK wafer sample and one Large-Area Avalanche Photodiode (LA-APD) from EXO-200. The reflectivity is determined to be 25-36% at an angle of incidence of 20{\deg} for the four samples and increases to up to 65% at 70{\deg} for the LA-APD and the FBK samples. The Hamamatsu VUV4 SiPM shows a decline with increasing angle of incidence. The reflectivity results will be incorporated in upcoming light response simulations of the nEXO detector., Comment: 18 pages, 11 figures

The nEXO neutrinoless double beta decay experiment is designed to use a time projection chamber and 5000 kg of isotopically enriched liquid xenon to search for the decay in $^{136}$Xe. Progress in the detector design, paired with higher fidelity in its simulation and an advanced data analysis, based on the one used for the final results of EXO-200, produce a sensitivity prediction that exceeds the half-life of $10^{28}$ years. Specifically, improvements have been made in the understanding of production of scintillation photons and charge as well as of their transport and reconstruction in the detector. The more detailed knowledge of the detector construction has been paired with more assays for trace radioactivity in different materials. In particular, the use of custom electroformed copper is now incorporated in the design, leading to a substantial reduction in backgrounds from the intrinsic radioactivity of detector materials. Furthermore, a number of assumptions from previous sensitivity projections have gained further support from interim work validating the nEXO experiment concept. Together these improvements and updates suggest that the nEXO experiment will reach a half-life sensitivity of $1.35\times 10^{28}$ yr at 90% confidence level in 10 years of data taking, covering the parameter space associated with the inverted neutrino mass ordering, along with a significant portion of the parameter space for the normal ordering scenario, for almost all nuclear matrix elements. The effects of backgrounds deviating from the nominal values used for the projections are also illustrated, concluding that the nEXO design is robust against a number of imperfections of the model., Comment: 26 pages, 19 figures, version accepted by Journal of Phys. G

The Center for Underground Physics (CUP) of the Institute for Basic Science (IBS) is searching for the neutrinoless double-beta decay (0{\nu}\b{eta}\b{eta}) of 100Mo in the molybdate crystals of the AMoRE experiment. The experiment requires pure scintillation crystals to minimize internal backgrounds that can affect the 0{\nu}\b{eta}\b{eta} signal. For the last few years, we have been growing and studying Li2MoO4 crystals in a clean-environment facility to minimize external contamination during the crystal growth. Before growing Li2100MoO4 crystal, we have studied Li2natMoO4 crystal growth by a conventional Czochralski (CZ) grower. We grew a few different kinds of Li2natMO4 crystals using different raw materials in a campaign to minimize impurities. We prepared the fused Al2O3 refractories for the growth of ingots. Purities of the grown crystals were measured with high purity germanium detectors and by inductively coupled plasma mass spectrometry. The results show that the Li2MoO4 crystal has purity levels suitable for rare-event experiments. In this study, we present the growth of Li2MoO4 crystals at CUP and their purities., Comment: 10 pages, 3 figures, INSTR'20 conference (Novosibirsk, Feb. 24-28, 2020)

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden nonunique β-decay transition ^{137}Xe(7/2^{-})→^{137}Cs(7/2^{+}). The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultralow background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal to background ratio of more than 99 to 1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden nonunique β-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

The Advanced Molybdenum-based Rare process Experiment in its second phase (AMoRE-II) will search for neutrinoless double-beta (0{\nu}\b{eta}\b{eta}) decay of 100Mo in 200 kg of molybdate crystals. To achieve the zero-background level in the energy range of the double-beta decay Q-value of 100Mo, the radioactive contamination levels in AMoRE crystals should be low. 100EnrMoO3 powder, which is enriched in the 100Mo isotope, is used to grow the AMoRE crystals. A shielded array of fourteen high-purity germanium detectors with 70% relative efficiency each was used for the measurement of background activities in a sample of 9.6-kg powder. The detector system named CAGe located at the Yangyang underground laboratory was designed for measuring low levels of radioactivity from natural radioisotopes or cosmogenic nuclides such as 228Ac, 228Th, 226Ra, 88Y, and 40K. The activities of 228Ac and 228Th in the powder sample were 0.88 \pm 0.12 mBq/kg and 0.669 \pm 0.087 mBq/kg, respectively. The activity of 226Ra was measured to be 1.50 \pm 0.23 mBq/kg. The activity of 88Y was 0.101 \pm 0.016 mBq/kg. The activity of 40K was found as 36.0 \pm 4.1 mBq/kg., Comment: 24 pages, 10 figures, 5 tables

Advanced Mo-based Rare process Experiment (AMoRE) – II led by Center for Underground Physics (CUP) will search for neutrinoless double beta ($0v\beta\beta$) decay of $^{100}$Mo, using molybdate crystals such as $^{40}Ca^{100}MoO_3$ (CMO) crystals [1]. Because the theorized 0νββ decay would happen rarely, it is important to reach zero-background level around the region of interest near 3 MeV. Therefore, it is necessary to check the raw material of the crystal, the $^{100}MoO_3$ powder, for trace levels of radioactive contamination. The High Purity Germanium (HPGe) detector group operates an array of 14 HPGe detectors, referred to as CUP Array of Germanium (CAGe), at the YangYang underground Laboratory (Y2L) in Korea. By measuring $^{100}MoO_3$ powder samples in the CAGe, we obtained activity levels of $^{226}$Ra (1.6 ± 0.3 mBq/kg), $^{40}$K (12 ± 3 mBq/kg), 228Ac (344 ± 71 $\mu$Bq/kg), $^{228}$Th (244 ± 50 $\mu$Bq/kg), and $^{88}$Y(33 ± 8 $\mu$Bq/kg). Data analysis and experimental methods are discussed in this report.

The Center for Underground Physics (CUP) at Institute for Basics Science (IBS) has been conducting and preparing a few ultra-low background rare event experiments at the YangYang underground Laboratory (Y2L). In order to keep the background levels in the experiments low enough, it is critical to screen raw materials or detector components to be used in the detectors. For the screening, a number of ultra-low radioactivity detectors are developed and installed. Among the detectors installed, we have a number of HPGe (High Purity Germanium) detectors in the Y2L for measurements of gammas from the background nuclei. Two of 100% p-type coaxial single HPGe detectors were installed and have been running from 2016 for the measurement of samples with close to 100% running time. In addition, an array of 14 HPGe detectors was installed in 2017 spring after screening the array detector materials with the single HPGe detectors for an efficient measurement of gamma rays from samples with bigger volumes. Various scintillation crystals such as CaMoO4, Li2MoO4, and NaI(Tl) have been grown with purified raw materials and tested for their radioactivity background levels. In this contribution, a summary of their developments and performances will be presented.

The Center for Underground Physics (CUP) at the Institute for Basic Science (IBS) has been conducting two major experiments, the COSINE experiment for dark matter search and the AMoRE experiment for neutrinoless double beta decay search. The COSINE experiment is using NaI:Tl scintillation crystals and the AMoRE is studying the 100Mo based scintillation crystals such as CaMoO_{4}(CMO), Li_{2}MoO_{4}(LMO), and etc. In order to develop ultra-pure scintillation crystals for the two experiments, we have built a clean-environment facility to minimize external contamination during the crystal growth. Here, we report the crystal growth facility and the internal background levels of the materials and grown crystals.

The gamma transitions with E$_{\gamma}$ > 3 MeV from decay of $^{208}$Tl decay have not been observed and their transition intensities were known only as upper limit values. New measurements with improved sensitivity are desirable for understanding nuclear decay properties of the nucleus and high energy gamma backgrounds in rare decay experiments such as neutrinoless double beta decay searches. A ThO$_2$ powder sample was used as a $^{208}$Tl source and was measured with a 100% High Purity Germanium(HPGe) detector in the Yangyang Underground Laboratory(Y2L) operated by the Center for Underground Physics(CUP) to obtain more accurate numbers of the high energy gamma intensities from $^{208}$Tl. The experimental setup, Monte Carlo simulation studies for detection efficiencies, and preliminary results are reported in this proceeding.

Observations of galaxies and primordial radiation suggest that the Universe is made mostly of non-luminous dark matter. Several types of new fundamental particles have been proposed as candidates for dark matter such as weakly interacting massive particles (WIMPs) but no definitive signal has been seen despite concerted efforts by many collaborations. One exception is the much-debated claim by the DAMA collaboration of a statistically significant annual modulation in the event rate of their experiment with a period and phase consistent with that expected from WIMP dark matter. Several groups have been working to develop experiments with the aim of reproducing DAMA's results using the same target medium. Here we report results from the initial operation of the COSINE-100 experiment. COSINE-100 uses sodium iodide as the target medium-the same medium as DAMA-and is designed to carry out a model-independent test of DAMA's claim. Initial data based on the first 59.5 days indicate that there is no excess of events over the expected background, confirming that DAMA's annual modulation signal is in severe tension with results from other experiments under the assumption of dark matter having spin independent interactions and the Standard Halo Model. COSINE-100 is now taking data to study the presence of dark matter-induced annual modulation in the event rate of the sodium iodide detectors., 26 pages, 9 figures

nEXO is a proposed experiment to search for the neutrino-less double beta decay ($0\nu\beta\beta$) of $^{136}$Xe in a tonne-scale liquid xenon time projection chamber (TPC). The nEXO TPC will be equipped with charge collection tiles to form the anode. In this work, the charge reconstruction performance of this anode design is studied with a dedicated simulation package. A multi-variate method and a deep neural network are developed to distinguish simulated $0\nu\beta\beta$ signals from backgrounds arising from trace levels of natural radioactivity in the detector materials. These simulations indicate that the nEXO TPC with charge-collection tiles shows promising capability to discriminate the $0\nu\beta\beta$ signal from backgrounds. The estimated half-life sensitivity for $0\nu\beta\beta$ decay is improved by $\sim$20$~(32)\%$ with the multi-variate~(deep neural network) methods considered here, relative to the sensitivity estimated in the nEXO pre-conceptual design report.

A calcium molybdate ( $\text{CaMoO}_{4}$ ) crystal scintillator, with molybdenum enriched in $^{100}\text{Mo}$ and calcium depleted in $^{48}\text{Ca}$ ( $^{40}\text{Ca}{}^{100}\text{MoO}_{4}$ ), was developed by the Advanced Molybdenum based Rare process Experiment (AMoRE) collaboration to search for a neutrinoless double beta ( $0\nu \beta \beta $ ) decay of $^{100}\text{Mo}$ . We are planning to use about 10 kg of $^{40}\text{Ca}{}^{100}\text{MoO}_{4}$ crystals as cryogenic bolometers for the first phase of the experiment (AMoRE-I) at the Yang Yang underground laboratory (Y2L) in Korea. This experiment calls for an extremely low level of radioactive contamination in detectors, particularly by thorium, uranium, and radium decay chains. We measured scintillation properties and radioactive contamination of $\text{CaMoO}_{4}$ and $^{40}\text{Ca}{}^{100}\text{MoO}_{4}$ crystals at the Y2L. We also estimated the acceptable level of internal radioactive background using Monte Carlo simulation for the AMoRE-I.

We apply deep neural networks (DNN) to data from the EXO-200 experiment. In the studied cases, the DNN is able to reconstruct the relevant parameters - total energy and position - directly from raw digitized waveforms, with minimal exceptions. For the first time, the developed algorithms are evaluated on real detector calibration data. The accuracy of reconstruction either reaches or exceeds what was achieved by the conventional approaches developed by EXO-200 over the course of the experiment. Most existing DNN approaches to event reconstruction and classification in particle physics are trained on Monte Carlo simulated events. Such algorithms are inherently limited by the accuracy of the simulation. We describe a unique approach that, in an experiment such as EXO-200, allows to successfully perform certain reconstruction and analysis tasks by training the network on waveforms from experimental data, either reducing or eliminating the reliance on the Monte Carlo., Accepted version. 33 pages, 28 figures

Future tonne-scale liquefied noble gas detectors depend on efficient light detection in the VUV range. In the past years Silicon Photomultipliers (SiPMs) have emerged as a valid alternative to standard photomultiplier tubes or large area avalanche photodiodes. The next generation double beta decay experiment, nEXO, with a 5 tonne liquid xenon time projection chamber, will use SiPMs for detecting the $178\,\text{nm}$ xenon scintillation light, in order to achieve an energy resolution of $\sigma / Q_{\beta\beta} = 1\, \%$. This paper presents recent measurements of the VUV-HD generation SiPMs from Fondazione Bruno Kessler in two complementary setups. It includes measurements of the photon detection efficiency with gaseous xenon scintillation light in a vacuum setup and dark measurements in a dry nitrogen gas setup. We report improved photon detection efficiency at $175\,\text{nm}$ compared to previous generation devices, that would meet the criteria of nEXO. Furthermore, we present the projected nEXO detector light collection and energy resolution that could be achieved by using these SiPMs., Comment: 11 pages, 13 figures, 2 tables

COSINE is a dark matter search experiment based on an array of low background NaI(Tl) crystals located at the Yangyang underground laboratory. The assembly of COSINE-100 was completed in the summer of 2016 and the detector is currently collecting physics quality data aimed at reproducing the DAMA/LIBRA experiment that reported an annual modulation signal. Stable operation has been achieved and will continue for at least 2 years. Here, we describe the design of COSINE-100, including the shielding arrangement, the configuration of the NaI(Tl) crystal detection elements, the veto systems, and the associated operational systems, and we show the current performance of the experiment., Institute for Basic Science ( IBS-R016-A1), University of Illinois at Urbana-Champaign, Alfred P. Sloan Foundation (Fellowship), National Science Foundation (U.S.) (Grant PHY-1457995), National Science Foundation (U.S.) (Grant PHY-1151795), National Science Foundation (U.S.) (Grant DGE-1122492), National Science Foundation (U.S.) (Grant DGE1256259), Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin. Alumni Research Foundation, Yale University, United States. National Nuclear Security Administration (Grant DE-FC52-08NA28752), Science and Technology Facilities Council (Great Britain) (Grant ST/N000277/1), Science and Technology Facilities Council (Great Britain) (Grant ST/K001337/1), Conselho Nacional de Pesquisas (Brazil) (Grant 2017/02952-0 FAPESP)

We report on the performance of silicon photomultiplier (SiPM) light sensors operating in electric field strength up to 30 kV/cm and at a temperature of 149K, relative to their performance in the absence of an external electric field. The SiPM devices used in this study show stable gain, photon detection efficiency, and rates of correlated pulses, when exposed to external fields, within the estimated uncertainties. No observable physical damage to the bulk or surface of the devices was caused by the exposure., Comment: 16 pages, 12 figures, 2 tables and two conferences (INPC2016 and TIPP2017)

We report the observation of two-neutrino double-beta decay in (136)Xe with T(1/2) = 2.11 ± 0.04(stat) ± 0.21(syst) × 10(21) yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for (136)Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

The KamLAND experiment has determined a precise value for the neutrino oscillation parameter $\Delta m^{2}_{21}$ and stringent constraints on $\theta_{12}$. The exposure to nuclear reactor anti-neutrinos is increased almost fourfold over previous results to 2.44$\times10^{32}$ proton-yr due to longer livetime and an enlarged fiducial volume. An undistorted reactor $\bar{\nu}_{e}$ energy spectrum is now rejected at >5$\sigma$. Extending the analysis down to the inverse beta decay energy threshold, and incorporating geo-neutrinos, gives a best-fit at $\Delta m^{2}_{21}$= $7.58^{+0.14}_{-0.13}(stat)^{+0.15}_{-0.15}(syst)\times10^{-5}$ eV$^{2}$ and $\tan^2 \theta_{12}$=$0.56^{+0.10}_{0.07}(stat)^{+0.10}_{-0.06}(syst)$. Local $\Delta \chi^2$-minima at higher and lower $\Delta m^{2}_{21}$ are disfavored at >4$\sigma$. Combining with solar neutrino data, we obtain $\Delta m^{2}_{21}$= $7.59^{+0.21}_{-0.21}\times10^{-5}$ eV$^{2}$ and $\tan^2 \theta_{12}$=$0.47^{+0.06}_{-0.05}$., Comment: Version as published in PRL. Revised Fig. 2 (allowed contours) due to an error in the figure generating code (numbers or conclusions did not change). The full dChi2-map for this analysis is available at http://www.awa.tohoku.ac.jp/KamLAND/chi2map_3rdresult/chi2map.html . Fig. 3 (low E spectrum) was dropped due to space limitations

We present new accurate measurements of the differential cross section $\ensuremath{\sigma}(\ensuremath{\theta})$ and the proton analyzing power ${A}_{y}$ for proton-$^{3}\mathrm{He}$ elastic scattering at various energies. A supersonic gas-jet target has been employed to obtain these low-energy cross-section measurements. The $\ensuremath{\sigma}(\ensuremath{\theta})$ distributions have been measured at ${E}_{p}=0.99$, 1.59, 2.24, 3.11, and 4.02 MeV. Full angular distributions of ${A}_{y}$ have been measured at ${E}_{p}=1.60$, 2.25, 3.13, and 4.05 MeV. This set of high-precision data is compared to four-body variational calculations employing realistic nucleon-nucleon ($\mathit{NN}$) and three-nucleon ($3N$) interactions. For the unpolarized cross section, the agreement between the theoretical calculation and data is good when a $3N$ potential is used. The comparison between the calculated and measured proton analyzing powers reveals discrepancies of approximately 50% at the maximum of each distribution. This is analogous to the existing ``${A}_{y}$ puzzle'' known for the past 20 years in nucleon-deuteron elastic scattering.

New experimental results for the cross section and ${A}_{yy}$ tensor analyzing power observables of the $^{3}\mathrm{He}(d,p)^{4}\mathrm{He}$ reaction at a scattering angle of $\ensuremath{\theta}=0\ifmmode^\circ\else\textdegree\fi{}$ are presented for ${E}_{d}=0.52,0.89,$ and $1.49\phantom{\rule{0.3em}{0ex}}\text{MeV}$, and all linearly independent scattering amplitudes at this angle are calculated. A hybrid $R\text{\ensuremath{-}}\text{matrix}+\text{potential}$ model is used to fit these results and other $^{3}\mathrm{He}(d,p)^{4}\mathrm{He}$ reaction data for ${E}_{d}l1\phantom{\rule{0.3em}{0ex}}\text{MeV}$. This analysis indicates significant direct process contributions to the reaction mechanism.

Background Advances in molecular biology and improved understanding of tumour biology have led to the development of novel treatments for cancer. Trastuzumab (Herceptin; Genentech, San Francisco, California, USA) is a monoclonal antibody directed against human epidermal growth factor receptor (HER) 2 protein, which is overexpressed in a wide variety of human cancers, including 20–30 per cent of human breast cancers. HER-2 plays an important role in oncogenic transformation, tumorigenesis and metastatic spread. Overexpression is associated with a poor prognosis and predicts a poor response to several treatment modalities. Method Literature relating to the monoclonal antibody was identified by a Medline literature search and by cross-referencing from the references of seminal articles on the subject. Four major clinical trials were identified and reviewed. Results and conclusion In clinical trials approximately 15–20 per cent of patients with HER-2-overexpressing tumours benefited from treatment with trastuzumab. In sensitive patients the antibody appeared to have intrinsic anticancer activity when given as a single agent. In combination chemotherapy it appeared to act synergistically with other agents. Ongoing research is evaluating trastuzumab in combination with numerous standard chemotherapy regimens and with other novel chemotherapeutic agents. Clinical trials have also revealed several serious side-effects of monoclonal antibody therapy. Most notable is an unpredictable cardiotoxicity, especially when used in combination with anthracycline-based chemotherapy regimens.

To investigate the survival and behavior of retinal pigment epithelium (RPE) microaggregates transplanted onto hydraulically debrided Bruch's membrane and to compare results of using three different vehicles for cell delivery.RPE microaggregates obtained from male cats were transplanted onto the tapetal area of female cats after native RPE was debrided. For the control, one of three vehicles was introduced into the debridements. Each transplant or control specimen was analyzed histologically and immunohistochemically. Transplanted male RPE cells were identified by in situ labeling of the cat Y chromosome.Histologically, significant numbers of condensed, darkly stained RPE nuclei were observed in all transplants compared with few TUNEL-positive RPE cells. Cellular retinaldehyde-binding protein was present up to day 7 in all RPE cells in transplants. In both transplant and control specimens, the antibody against the Ki-67 nuclear antigen labeled some RPE cells at day 3. TUNEL-positive outer nuclear layer nuclei were most frequently observed at day 1, but were much less frequent at 7 days in both transplant and control specimens.Transplanted RPE appeared to retain at least some markers of differentiation up to 7 days after surgery. Some proliferation of transplanted RPE cells was also seen. Apoptotic cell death of transplanted RPE, as judged by TUNEL staining was observed rarely. RPE transplants imposed no adverse effect on the overlying retina. RPE survival appeared to be similar with each of the three vehicles for cell delivery.

Angular distributions of sigma(theta), A_y, iT_11, T_20, T_21, and T_22 have been measured for d-p scattering at E_c.m.=667 keV. This set of high-precision data is compared to variational calculations with the nucleon-nucleon potential alone and also to calculations including a three-nucleon (3N) potential. Agreement with cross-section and tensor analyzing power data is excellent when a 3N potential is used. However, a comparison between the vector analyzing powers reveals differences of approximately 40% in the maxima of the angular distributions which is larger than reported at higher energies for both p-d and n-d scattering. Single-energy phase-shift analyses were performed on this data set and a similar data set at E_c.m.=431.3 keV. The role of the different phase-shift parameters in fitting these data is discussed., Comment: 18 pages, 6 figures

A new measurement of the p-d differential cross section at Ep= 1 MeV has been performed. These new data and older data sets at energies below the deuteron breakup are compared to calculations using the two-nucleon Argonne v18 and the three-nucleon Urbana IX potentials. A quantitative estimate of the capability of these interactions to describe the data is given in terms of a chi^2 analysis. The chi^2 per datum drastically improves when the three-nucleon interaction is included in the Hamiltonian., Comment: 13 pages, 5 figures, to be published in Phys. Rev. C

To characterize changes in the retina, retinal pigment epithelium (RPE), and choriocapillaris with fluorescein angiography (FA) and histology after hydraulic or abrasive RPE debridement in 26 domestic short-haired cats.Hydraulic debridement was produced by injecting balanced salt solution forcefully into the subretinal space. For abrasive debridement, RPE were removed with a silicone-tipped cannula after creating a localized retinal detachment. The FAs were performed after surgery, and tissue was prepared for light microscopy (LM) and scanning electron microscopy (SEM).Sixty-seven blebs were examined by FA 1 hour after surgery, and RPE debridement was confirmed by SEM or LM in 15 blebs from 10 animals. Hyperfluorescence and variable central fluorescein leakage were seen 1 week after surgery in 52 of 53 blebs (which includes all 27 blebs from the 1-week timepoint and 26 of 29 blebs from the 4-week timepoint that were studied by FA 1 week after surgery). Choriocapillary filling delays were seen in no hydraulic debridements, but in 11 of 14 abrasive blebs, especially in areas showing leakage late in the angiogram. In 1 of 13 hydraulic and 12 of 14 abrasive debridements, areas of late dye leakage had no RPE with outer retinal degeneration. At the 4-week timepoint, 1 of 17 hydraulic and 10 of 12 abrasive debridements had foci of delayed or absent choriocapillary perfusion by FA, with degenerated outer retina, no RPE, and choriocapillary atrophy by histologic analysis.Abrasive debridement is more commonly associated with abnormal FAs and with incomplete RPE repopulation, choriocapillaris atrophy, and outer retinal degeneration than is hydraulic debridement. This clinicopathologic study may give insight into FA interpretation after choroidal neovascular membrane removal in human patients.

The Drosophila mutant, oraJK84, lacks rhabdomeres in the major (R1-6) class of photoreceptors because these rhabdomeres rapidly degenerate in young flies. Genetic analysis reveals that oraJK84 actually contains two mutations (a ninaE and an ort allele) that affect the visual process. The mutation in ort appears to have no effect on photoreceptor structure. The other mutation occurs within the ninaE gene, which encodes the species of rhodopsin found in the R1-6 class of photoreceptors. Our analysis shows that this mutation is responsible for R1-6 rhabdomere degeneration in oraJK84 mutants. We also examined a ninaE mutant, denoted ninaEo117, that produces no ninaE transcript. The morphological phenotype observed in ninaEo117 is similar to that seen in oraJK84 mutants. We conclude that rhodopsin plays a vital role in maintaining photoreceptor structure in Drosophila.