High Absolute Sensitivity Research Articles

Dual-mode luminescent core-shell nanoarchitectures for highly sensitive optical nanothermometry

Currently, FIR-based luminescent nanothermometry has aroused wide concern for its promising applications in fast-moving objects, harsh environments and microscopic temperature. Synchronously promoting the absolute and relative sensitivities of optical thermometers is one of the significant issues at present. In this work, a new nanothermometry strategy to possess both high absolute and relative sensitivities have been proposed by coupling of thermally-coupled-levels-based technique with non-thermally-coupled-levels method in the core-shell designed nanomaterials. Following this strategy, the core-shell-structured NaGdF4:Yb,Er@ NaYF4:Ce,Tb,Eu nanocrystals have been successfully prepared. Remarkably, the adverse cross-relaxation among different activators is extremely suppressed owing to the spatial separation of Er3+ and Eu3+,Tb3+ activators, being conducive to the realization of both intense green upconverting emissions and yellow downshifting luminescence. Moreover, the temperature-sensitive dual-mode luminescent behaviors of core-shell nanomaterials are systematically studied to probe the possible application in FIR-related luminescent thermometry. Specially, the thermally-coupled-levels-based FIR of Er3+:2H11/2 → 4I15/2 transition to Er3+: 4S3/2 → 4I15/2 one and non-thermally-coupled-levels-based FIR of Eu3+:5D0→7F2 transition to Tb3+:5D4→7F6 one are proved to be applicable as temperature probes, leading to the achievement of dual-mode temperature sensing. Using the pre-designed core@shell nanoarchitectures, the absolute sensitivity can reach up to 1.02% K−1 based on Eu3+,Tb3+ Stokes emissions and the relative sensitivity could reach as high as 1.12% K−1 based on Er3+ anti-Stokes luminescence. We believe that this study provides a valid approach for developing high-performance optical nanothermometers.

Er3+/Yb3+ co-doped nanocrystals modified with 6-aminocaproic acid for temperature sensing in biomedicine.

We report β-PbF2:Er3+/Yb3+ nanocrystals (NCs) modified with 6-aminocaproic acid (6AA) via wet chemical etching of glass ceramics (GCs). NCs body-doped with trivalent rare-earth (RE3+) ions were released from the GCs by etching of the glass matrix and modified with bifunctional 6AA ligands to enhance their water solubility. They have good stability in water with an average diameter of 56 nm and display efficient green (521, 550 nm) and red (660 nm) emission under the excitation of a 940 nm laser. High absolute sensitivity (SA) and relative sensitivity (SR) (0.0027 K−1 and 1.18% K−1, respectively) and high resolution (0.25 K) were achieved for temperature sensing in the biological temperature range, using the fluorescence intensity ratio (FIR) technique. All of the experimental results indicate that the Er3+/Yb3+ co-doped NCs modified with 6AA may potentially be useful as fluorescent biological temperature sensors.

Upconversion luminescence, intrinsic optical bistability, and optical thermometry in Ho3+/Yb3+: BaMoO4 phosphors

Ho3+/Yb3+: BaMoO4 phosphors with different concentrations were fabricated by a gel combustion method. The upconversion (UC) luminescence, intrinsic optical bistability, and the corresponding mechanisms were reported for the present system. The optical thermometric properties based on red (5F5→5I8) and green (5F4/5S2→5I8) emissions were studied. The sensing sensitivities could be tuned by manipulating the cooperative energy transfer process. The highest absolute sensitivity was 99 × 10−4 K−1 at 573 K, which is larger than that of many previous UC materials.

Electronic structure, upconversion luminescence and optical temperature sensing behavior of Yb3+-Er3+/Ho3+ doped NaLaMgWO6

To develop new upconversion (UC) phosphors of high sensitivity for temperature sensing, a series of Yb3+-Er3+ and Yb3+-Ho3+ doped NaLaMgWO6 (NLMW) samples were designed via solid-state reaction method. The phase purity was examined by XRD patterns, indicating the obtained samples are all single-phase. The morphology was characterized by SEM and TEM techniques, revealing smooth particle surface. The electronic structure of NLMW was analyzed theoretically, and the optical bandgap obtained was compared with the experimental results. Upon 980 nm excitation, the characteristic transitions of Er3+ and Ho3+ were found, and their optimal concentrations were determined to be 2 and 3 mol%, respectively. By investigating the temperature-dependence of NLMW:0.1 Yb3+,0.02Er3+, it was found that the thermally-coupled 2H11/2 and 4S3/2 levels of Er3+ cause a large fluorescence intensity ratio (FIR) for 528 and 550 nm emissions, which can generate a high absolute sensitivity (0.0107 K−1 at 508 K). The corresponding explanation was given by using the dependence of UC emissions on excitation power density. For the NLMW:0.1 Yb3+,0.03Ho3+ phosphor, the non-thermally-coupled (5F4,5S2) and 5F5 levels were employed to character the temperature-sensing behavior of Ho3+. High absolute sensitivity of 8.9×10−3 K−1 was gained at 548 K. The reason for the different change of 543 and 658 nm emissions intensities with temperature was conducted by the phonon-electron coupling.

Photoreceptors and eyes of pikeperch Sander lucioperca, pike Esox lucius, perch Perca fluviatilis and roach Rutilus rutilus from a clear and a brown lake

The photoreceptors and eyes of four fish species commonly cohabiting Fennoscandian lakes with different light transmission properties were compared: pikeperch Sander lucioperca, pike Esox lucius, perch Perca fluviatilis and roach Rutilus rutilus. Each species was represented by individuals from a clear (greenish) and a humic (dark brown) lake in southern Finland: Lake Vesijärvi (LV; peak transmission around 570 nm) and Lake Tuusulanjärvi (LT; peak transmission around 630 nm). In the autumn, all species had almost purely A2-based visual pigments. Rod absorption spectra peaked at c.526 nm (S. lucioperca), c. 533 nm (E. lucius) and c. 540 nm (P. fluviatilis and R. rutilus), with no differences between the lakes. Esox lucius rods had remarkably long outer segments, 1.5-2.8-fold longer than those of the other species. All species possessed middle-wavelength-sensitive (MWS) and long-wavelength-sensitive (LWS) cone pigments in single, twin or double cones. Rutilus rutilus also had two types of short-wavelength sensitive (SWS) cones: UV-sensitive [SWS1] and blue-sensitive (SWS2) cones, although in the samples from LT no UV cones were found. No other within-species differences in photoreceptor cell complements, absorption spectra or morphologies were found between the lakes. However, E. lucius eyes had a significantly lower focal ratio in LT compared with LV, enhancing sensitivity at the expense of acuity in the dark-brown lake. Comparing species, S. lucioperca was estimated to have the highest visual sensitivity, at least two times higher than similar-sized E. lucius, thanks to the large relative size of the eye (pupil) and the presence of a reflecting tapetum behind the retina. High absolute sensitivity will give a competitive edge also in terms of short reaction times and long visual range.

Optical thermometry based on anomalous temperature-dependent 1.53 μm infrared luminescence of Er3+ in BaMoO4: Er3+/Yb3+ phosphor

The temperature dependences of 1.53 μm near infrared and green upconversion (UC) emissions of Er3+ ion have been investigated in Er3+/Yb3+: BaMoO4 powders upon 980 nm excitation. Interestingly, an anomalous enhancement of 1.53 μm luminescence intensity with increasing temperature is observed, which is interpreted based on the phonon-assisted nonradiative process from 4I11/2 to 4I13/2 level. Moreover, the emission intensities from various Stark transitions 4I13/2(Yi)→4I15/2(Zj) show different changing rates with temperature, which is in favor of optical thermometry application based on fluorescence intensity ratio (FIR) technique. The results show that the utilization of FIR-1 (I1504/I1531) from two Stark transitions with the same power-dependence is beneficial to obtain consistent results at different excitation power densities, and avoid measurement error resulted from the power density variation. Besides, when FIR-Green (I533/I557) is used as the thermometric index, a high absolute sensitivity of 115 × 10−4 at 430 K can be obtained. Therefore, Er3+/Yb3+: BaMoO4 is promising for optical thermometry.

Ultrahigh-sensitive optical temperature sensing in Pr3+:Y2Ti2O7 based on diverse thermal response from trap emission and Pr3+ red luminescence

In this work, a new optical thermometer relying on highly temperature-dependent 1D2 Pr3+ emission and temperature insensitive Y2Ti2O7 trap emission is reported. Based on the fluorescence intensity ratio (FIR) between them, Pr3+: Y2Ti2O7 with remarkably high absolute and relative sensitivities of ~ 983 × 10−4 K−1 and 5.25% K−1 as well as good signal discriminability is realized. It also exhibits a tunable luminescent color from red to purplish blue with temperature from 289 to 573 K. The strong thermal quenching of 1D2 Pr3+ emission is mainly related to the charge transfer state (CTS). Similarly, Pr3+: Gd2Ti2O7 phosphor also demonstrates a favorable temperature sensing feature, indicating the temperature sensing strategy based on the combination of host trap emission and CTS interfered Pr3+ luminescence is a promising pathway to develop high-performance optical thermometric materials.

Temperature-dependent persistent luminescence of SrAl2O4:Eu2+, Dy3+, Tb3+: a strategy of optical thermometry avoiding real-time excitation.

A new strategy of optical thermometry is realized by long persistent luminescence phosphor SrAl2O4:Eu2+, Dy3+, Tb3+ (SAEDT). Under different temperatures, SAEDT shows bright afterglow emissions after cessation of the UV excitation. The afterglow color of the SAEDT sample is blue at 60K and gradually changed into green at 240K. The normalized afterglow spectra at different temperatures give a dramatic change of fluorescence intensity ratio between the blue band and the green band. Not only has this material exhibited a high absolute sensitivity and relative sensitivity for temperature sensing, but it also has the great advantage of eliminating the heating effect due to avoidance of real-time direct excitation.

Analysis of Efficacy and Accuracy of 2 Vacuum-Assisted Breast Biopsy Devices: Mammotome and Elite

BackgroundUltrasound-guided vacuum-assisted breast biopsy (US-VABB) has recently replaced surgical biopsy as a result of its high diagnostic accuracy and low patient discomfort, and at present it relies mainly on 2 devices, Mammotome and, more recently, Mammotome Elite (Elite). Our purpose was to compare the efficacy of these 2 bioptical devices. Patients and MethodsWe performed US-VABB on 195 patients with Mammotome 8G or 11G in 130 patients and Elite 13G in 65 patients. Of these 195 patients, 95 were submitted to surgery for lumpectomy or mastectomy in case of malignant lesions or of lesions of uncertain malignant potential (B5 and B3), while the remaining 100 were strictly monitored clinically and radiologically for 12 to 24 months. ResultsBoth the devices showed high absolute sensitivity (96.2% for Mammotome and 83.3% for Elite), complete sensitivity (98.1% for Mammotome and 90.0% for Elite), specificity (92.3% for Mammotome and 94.3% for Elite), and diagnostic accuracy (99.1% for Mammotome and 95% for Elite), thus fulfilling criteria suggested by the European guidelines. Total underestimation rate seemed to be higher in the Elite cohort (14.2%) than in the Mammotome cohort (3.4%) (P = .02). However, none of the patients with a benign diagnosis (B2) presented any event during the follow-up period. ConclusionUS-VABB is an accurate method for sampling breast lesions. Our study did not show large, statistically significant differences in diagnostic accuracy between the Elite and Mammotome systems, except for a slight increase in diagnostic underestimation of benign pathologies when using the Elite.

Temperature sensing behavior in Yb3+–Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 phosphors based on upconversion and downshifting luminescence

To develop new phosphor materials for optical temperature sensing application, a series of Yb3+–Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 (CGS) phosphors were designed by solid-state reaction method. Upon 980 nm excitation, the green emission of Tb3+ was observed in the CGS:0.8Yb3+, xTb3+ (0.08 ≤ x ≤ 1.2) phosphors, which could be mainly owing to the cooperative energy transfer from Yb3+ to Tb3+. The corresponding upconversion (UC) luminescence mechanism was studied by using the dependence of UC emission intensity on excitation powder. The temperature-dependence indicates that the ratio of the Tb3+ emission intensities of I5D4 and I5D3 changes with temperature, which shows a linear relationship. The high absolute sensitivity was achieved to be about 0.431 K−1. Upon 463 nm excitation, the Eu3+ 5D0,1–7FJ transitions were found in the Eu3+-activated CGS. The investigation on temperature-dependence reveals that with increasing temperature the intensities of 5D0–7FJ transitions decrease but those of 5D1–7FJ transitions increase gradually, owing to the thermally coupled 5D0 and 5D1 levels. The fluorescence lifetime based temperature sensing properties was studied in this sample.

Investigation on Upconversion Luminescence and Optical Temperature Sensing Behavior for Ba2Gd2Si4O13:Yb3+-Er3+/Ho3+/Tm3+ Phosphors

To explore new phosphors for temperature sensing with high detection sensitivity, the Yb3+-Er3+/Ho3+/Tm3+ doped Ba2Gd2Si4O13 (BGS) was designed. Different strategies were introduced based on the upconversion (UC) luminescence. For BGS:0.2Yb3+,0.02Er3+, the fluorescence intensity ratio (FIR) of two green emissions of Er3+ shows a gradual enhancement with increasing temperature due to the thermally coupled levels. The piecewise expression of sensitivity was proposed in the temperature range of 293–553 K based on the Boltzmann distribution. For BGS:0.2Yb3+,0.01Ho3+, the FIR of the red to green emissions of Ho3+ changes with temperature, showing a linear relationship from 293 to 453 K. The absolute sensitivity was gained to be 0.0452 K–1. For BGS:0.2Yb3+,0.02Tm3+, the high absolute and relative sensitivities were both achieved by employing the thermally coupled (3F2,3F3) and 3H4 levels of Tm3+. The above study could have special reference to the development of new luminescent materials with high sensitivity.

Investigations on upconversion luminescence of K3Y(PO4)2:Yb3+-Er3+/Ho3+/Tm3+ phosphors for optical temperature sensing

A series of Yb3+-Er3+/Ho3+/Tm3+ doped K3Y(PO4)2 (KYP) phosphors were synthesized by solid-state reaction method. Several effective strategies for temperature sensing were introduced based on their upconversion (UC) luminescence properties. For Yb3+-Er3+ codoped KYP, it was found the relative intensities of different emissions of Er3+ change with temperature, and the repeatability of measurement was evaluated. The sensor sensitivities were calculated and compared based on the thermally coupled and non-thermally coupled levels of Er3+. For Yb3+-Ho3+ codoped KYP, red emission was obtained due to the strong 5F5-5I8 transition of Ho3+. With increasing temperature, the 5F5-5I8 and (5F4,5S2)-5I8 emissions show different decrease rates in intensity. The high absolute sensitivity of 0.078 K−1 was obtained from the dependence of the fluorescence intensity ratio (FIR) on temperature, but the relative sensitivity is low compared with that of Er3+ activated KYP. For Yb3+-Tm3+ codoped KYP, various emission peaks of Tm3+ have been found from the near-ultraviolet to near-infrared range. The temperature dependence of the FIR for (3F2,3F3)-3H6 and 3H4-3H6 transitions of Tm3+ reveals the relative sensitivity is more than twice as much as that of the Yb3+-Er3+ codoped KYP, but it shows a much lower absolute sensitivity due to the low FIR value.

Transparent Sr0.84Lu0.16F2.16: Yb3+, Er3+ glass ceramics: Elaboration, structure, up-conversion properties and applications

The development of optical temperature sensors is of fundamental and industrial importance for various applications. Despite the great advance in optical temperature-sensing techniques, challenges remain to search for novel sensing materials with low cost, easy fabrication and high sensitivity. Here, transparent glass ceramics (GC) embedded with cubic Sr0.84Lu0.16F2.16:Yb3+/Er3+ nano-crystals were prepared via thermal annealing on the parent glass. The optical and structural properties were investigated. The enhanced emission intensity, obvious Stark splitting and prolonged lifetimes of Er3+ confirm the enrichment of Er3+ ions into formed Sr0.84Lu0.16F2.16 nano-crystals. The temperature sensing performance of Yb3+/Er3+ ions in Sr0.84Lu0.16F2.16GC were investigated based on up-conversion intensity ratio (FIR) from thermally coupled emitting states of Er3+. High energy difference (ΔE = 839 cm−1) and high absolute sensitivity (27.4 × 10−4 K−1 at 606 K) are obtained. Our results reveal Sr0.84Lu0.16F2.16GC are excellent host for rare earth ions doping and potential candidate for optical thermometry.

Down-conversion luminescence and optical thermometric performance of Tb3+/Eu3+ doped phosphate glass

Tb3+/Eu3+ co-doped phosphate glasses were successfully synthesized by conventional melt-quenching method. The transmittance spectra and down-conversion optical properties were investigated by using UV–visible spectrophotometer and fluorescence spectrometer. All the glass samples show light transmittance of about 90%, and the color of luminescence could be tuned by altering the concentrations of Eu3+ ions. The decrease of the Tb3+ emission decay time in presence of Eu3+ ascertained that Tb3+ → Eu3+ non-radiative energy transfer happened. The research of energy transfer between Tb3+ and Eu3+ based on the Inokuti-Hirayama model revealed that an electric dipole–dipole interaction might be the predominant mechanism. Under the excitation of 378 nm, the temperature dependent luminescence of Tb3+/Eu3+ co-doped glasses was carefully investigated in the temperature range of 303–753 K. Impressively, a high absolute sensitivity Sa of 1.0% K−1 and a high relative sensitivity Sr of 11.67 × 10−3 K−1 at 753 K could be obtained. It is expected that the investigated glasses might be a promising candidate for solid-state lighting and optical thermometry.

Sensitivity-enhanced Tm3+/Yb3+ co-doped YAG single crystal optical fiber thermometry based on upconversion emissions

Optical thermometry based on Y3Al5O12 (YAG) single crystal optical fiber with end Tm3+/Yb3+ co-doped is presented. The YAG crystal fiber with end Tm3+/Yb3+ co-doped was grown by laser heated pedestal growth (LHPG) method. Under a 976 nm laser diode excitation, the upconversion (UC) emissions, originating from 3F2,3→3H6 and 3H4→3H6 transitions of Tm3+ ions, were investigated in the temperature range from 333 K to 733 K. Interestingly, the UC emission intensity of 3F2,3→3H6 transition was significantly enhanced with increase of temperature, as compared with the other Tm3+/Yb3+ co-doped materials. The temperature dependence of fluorescence intensity ratio (FIR) of these two emission bands (3F2,3/3H4→3H6) suggests that this doped YAG crystal fiber can be used as a highly sensitive optical thermal probe, which demonstrates a high absolute sensitivity with the maximum value of 0.021 K−1 at 733 K. In addition, due to the compact structure, strong mechanical strength and high thermal stability, such thermal probe may be a more promising candidate for temperature sensor with a high spatial resolution.

Wide-range thermometry based on green up-conversion of Yb3+/Er3+ co-doped KLu2F7 transparent bulk oxyfluoride glass ceramics

The development of optical temperature sensors is of fundamental and industrial importance for various applications. Despite the great advance in optical temperature-sensing techniques, challenges remain to search for novel sensing materials with low cost, easy fabrication, high sensitivity and wide temperature-sensing range. Here, bulk KLu2F7:Yb3+/Er3+ glass ceramics (GC), prepared by simple conversional melt-quenching method with subsequent heat-treatment, are carefully characterized for potential temperature sensor using fluorescence intensity ratio (FIR) technique. The structural and luminescent properties of KLu2F7:Yb3+/Er3+ GC are systematically investigated by XRD, TEM, up-conversion and lifetime measurement. Compared to other reported typical Er3+-doped temperature-sensing materials, Er3+ ions in KLu2F7 GC present wide temperature-sensing range (300–773K), large energy gap (861cm−1) and high absolute sensitivity (47.3 × 10−4K−1 at 620K). Our results indicate that KLu2F7:Yb3+/Er3+ GC are promising temperature sensing materials for designing highly sensitive FIR-based optical thermometers.

A Global Assessment of Runoff Sensitivity to Changes in Precipitation, Potential Evaporation, and Other Factors

AbstractPrecipitation (P) and potential evaporation (Ep) are commonly studied drivers of changing freshwater availability, as aridity (Ep/P) explains ∼90% of the spatial differences in mean runoff across the globe. However, it is unclear if changes in aridity over time are also the most important cause for temporal changes in mean runoff and how this degree of importance varies regionally. We show that previous global assessments that address these questions do not properly account for changes due to precipitation, and thereby strongly underestimate the effects of precipitation on runoff. To resolve this shortcoming, we provide an improved Budyko‐based global assessment of the relative and absolute sensitivity of precipitation, potential evaporation, and other factors to changes in mean‐annual runoff. The absolute elasticity of runoff to potential evaporation changes is always lower than the elasticity to precipitation changes. The global pattern indicates that for 83% of the land grid cells runoff is most sensitive to precipitation changes, while other factors dominate for the remaining 17%. This dominant role of precipitation contradicts previous global assessments, which considered the impacts of aridity changes as a ratio. We highlight that dryland regions generally display high absolute sensitivities of runoff to changes in precipitation, however within dryland regions the relative sensitivity of runoff to changes in other factors (e.g., changing climatic variability, CO2‐vegetation feedbacks, and anthropogenic modifications to the landscape) is often far higher. Nonetheless, at the global scale, surface water resources are most sensitive to temporal changes in precipitation.

Abstract 5410: Optimization and evaluation of SMART-Seq v4 kit for low input RNA sequencing

Abstract Recent advances in library preparation methodology from limiting amounts of total RNA have facilitated the characterization of rare cell-types in various biological systems. The SMART-Seq v4 Ultra Low Input RNA Kit incorporates a number of workflow improvements, including fewer purifications to increase yield, a locked nucleic acid (LNA) template-switching oligo to enhance stability, and an improved polymerase designed to reduce amplification bias of GC-rich regions. Certain workflow challenges remain however, including variability in library insert size, which can lead to less predictable sequencing results. We have modified the SMART-Seq v4 method to incorporate library size selection between 250-650 bp, and have characterized analytical performance of the modified procedure. A total of 63 libraries were generated using 10 pg - 10 ng of Universal Human Reference RNA (UHRR), Human Brain Reference RNA (HBRR), and total RNA isolated from multiple human tissues, including lung, colon, spleen, adrenal tumor, heart, and lung tumor. To facilitate the comparison between libraries, we normalized library read counts by down-sampling to 24 million reads prior to further processing with an internally-developed sequence analysis pipeline (RNAv9_rsem). The values for ERCC Limit of Detection ranged between 3-50 copies with a mean of 22 copies, which confirmed the high absolute sensitivity of SMART-seq v4 workflow. The total number of genes detected (RPKM, or reads per kilobase per million mapped >=3) varied as a function of the amount of input RNA, with as many as 19,500 genes detected. Gene detection was highly consistent across replicates utilizing 100 pg-10 ng input RNA, with a precipitous decline in genes detected using 10 pg of RNA input. This is due to less reliable detection of low abundance genes, which in turn leads to increased discordance in detected genes between replicates, possibly due to increased sampling error. Nonetheless, when genes are commonly detected, their normalized read counts are highly correlated at any given RNA input, with correlation coefficients (r) ranging from 0.977 to 0.993. Compared to previous versions of the SMARTer method, the modified SMART-Seq v4 procedure implemented at Q2 Solutions - EA Genomics significantly improved the percentage of reads aligned to the transcriptome, as well as the total number of genes detected, all with reduced technical variability. Our study demonstrates an improved strategy for expression profiling via RNA sequencing from limiting amounts of RNA. Citation Format: Dan Su, Thomas Halsey, Martin Buchkovich, Jason G. Powers, Steven Abbott, Jenny Shu, John Pufky, Michell Chang, Victor Weigman, Patrick Hurban. Optimization and evaluation of SMART-Seq v4 kit for low input RNA sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5410. doi:10.1158/1538-7445.AM2017-5410

Pumped-Up SU(1,1) Interferometry.

Although SU(1,1) interferometry achieves Heisenberg-limited sensitivities, it suffers from one major drawback: Only those particles outcoupled from the pump mode contribute to the phase measurement. Since the number of particles outcoupled to these "side modes" is typically small, this limits the interferometer's absolute sensitivity. We propose an alternative "pumped-up" approach where all the input particles participate in the phase measurement and show how this can be implemented in spinor Bose-Einstein condensates and hybrid atom-light systems-both of which have experimentally realized SU(1,1) interferometry. We demonstrate that pumped-up schemes are capable of surpassing the shot-noise limit with respect to the total number of input particles and are never worse than conventional SU(1,1) interferometry. Finally, we show that pumped-up schemes continue to excel-both absolutely and in comparison to conventional SU(1,1) interferometry-in the presence of particle losses, poor particle-resolution detection, and noise on the relative phase difference between the two side modes. Pumped-up SU(1,1) interferometry therefore pushes the advantages of conventional SU(1,1) interferometry into the regime of high absolute sensitivity, which is a necessary condition for useful quantum-enhanced devices.

An apposition compound eye adapted for nocturnal vision in the moth midge Clogmia albipunctata (Williston) (Diptera: Psychodidae)

Morphology and anatomy, dark/light adaptational changes and optics of the compound eyes of the nocturnal moth midge Clogmia albipunctata (Williston) are studied. Its apposition type of eye consists of approximately 260 well-separated ommatidia. Each ommatidium features a biconvex corneal lens covered by corneal nipples measuring around 17nm in height; a crystalline cone of the acone type; and an open (laterally fused) rhabdom formed by eight retinular cells (R1-R8). The corneal lens, whose biological significance is addressed, is composed of a thick yellow-coloured inner lens unit (ILU) surrounded by a thin, colourless outer lens unit (OLU). We identified two types of ommatidia: dorsally located T-type ommatidia and ventrally located P-type ommatidia. In the T-type ommatidia, the rhabdomeres of the retinular cells R7 and R8 are centrally located and are arranged in tandem with R7 above R8. In comparison, in the P-type ommatidia, only the R8 rhabdomere is central, whereas the R7 rhabdomere locates in the peripheral ring. Above the distal tip of the rhabdom, the crystalline cone and the PPCs form an aperture that dynamically changes its size under dark/light conditions, thus modulating the amount of light that reaches the photoreceptive layer. The Clogmia albipunctata eye has a low F-number of 1.2, a high interommatidial angle of 11° and a large eye parameter of 4.6μm·rad. The eye is characterized by relatively poor spatial resolution, but exhibits high absolute sensitivity.