Robust Probe Research Articles

Heisenberg versus standard scaling in quantum metrology with Markov generated states and monitored environment

Finding optimal and noise robust probe states is a key problem in quantum metrology. In this paper we propose Markov dynamics as a possible mechanism for generating such states, and show how the Heisenberg scaling emerges for systems with multiple `dynamical phases' (stationary states), and noiseless channels. We model noisy channels by coupling the Markov output to `environment' ancillas, and consider the scenario where the environment is monitored to increase the quantum Fisher information of the output. In this setup we find that the survival of the Heisenberg limit depends on whether the environment receives `which phase' information about the memory system.

Dijets in p + Pb collisions and their quantitative constraints for nuclear PDFs

We present a perturbative QCD analysis concerning the production of high-pT dijets in p+Pb collisions at the LHC. The next-to-leading order corrections, scale variations and free-proton PDF uncertainties are found to have only a relatively small influence on the normalized dijet rapidity distributions. Interestingly, however, these novel observables prove to retain substantial sensitivity to the nuclear effects in the PDFs. Especially, they serve as a more robust probe of the nuclear gluon densities at $x>0.01$, than e.g. the inclusive hadron production. We confront our calculations with the recent data by the CMS collaboration. These preliminary data lend striking support to the gluon antishadowing similar to that in the EPS09 nuclear PDFs.

The X-ray spectra of the first galaxies: 21 cm signatures

The cosmological 21cm signal is a physics-rich probe of the early Universe, encoding information about both the ionization and the thermal history of the intergalactic medium (IGM). The latter is likely governed by X-rays from star-formation processes inside very high redshift (z > 15) galaxies. Due to the strong dependence of the mean free path on the photon energy, the X-ray SED can have a significant impact on the interferometric signal from the cosmic dawn. Recent Chandra observations of nearby, star-forming galaxies show that their SEDs are more complicated than is usually assumed in 21cm studies. In particular, these galaxies have ubiquitous, sub-keV thermal emission from the hot interstellar medium (ISM), which generally dominates the soft X-ray luminosity (with energies < 1 keV, sufficiently low to significantly interact with the IGM). Using illustrative soft and hard SEDs, we show that the IGM temperature fluctuations in the early Universe would be substantially increased if the X-ray spectra of the first galaxies were dominated by the hot ISM, compared with X-ray binaries with harder spectra. The associated large-scale power of the 21cm signal would be higher by roughly a factor of three. More generally, we show that the peak in the redshift evolution of the large-scale (k = 0.2 1/Mpc) 21cm power is a robust probe of the soft-band SED of the first galaxies, and importantly, is not degenerate with their bolometric luminosities. On the other hand, the redshift of the peak constrains the X-ray luminosity and halo masses which host the first galaxies.

Quantitative monitoring of yeast fermentation using Raman spectroscopy.

Compared to traditional IR methods, Raman spectroscopy has the advantage of only minimal interference from water when measuring aqueous samples, which makes this method potentially useful for in situ monitoring of important industrial bioprocesses. This study demonstrates real-time monitoring of a Saccharomyces cerevisiae fermentation process using a Raman spectroscopy instrument equipped with a robust sapphire ball probe. A method was developed to correct the Raman signal for the attenuation caused by light scattering cell particulate, hence enabling quantification of reaction components and possibly measurement of yeast cell concentrations. Extinction of Raman intensities to more than 50 % during fermentation was normalized with approximated extinction expressions using Raman signal of water around 1,627 cm(-1) as internal standard to correct for the effect of scattering. Complicated standard multi-variant chemometric techniques, such as PLS, were avoided in the quantification model, as an attempt to keep the monitoring method as simple as possible and still get satisfactory estimations. Instead, estimations were made with a two-step approach, where initial scattering correction of attenuated signals was followed by linear regression. In situ quantification measurements of the fermentation resulted in root mean square errors of prediction (RMSEP) of 2.357, 1.611, and 0.633 g/L for glucose, ethanol, and yeast concentrations, respectively.

A unique carbazole–coumarin fused two-photon platform: development of a robust two-photon fluorescent probe for imaging carbon monoxide in living tissues

Two-photon fluorescent probes are favorable as powerful molecular tools for studies in biology and medicine. To construct two-photon fluorescent probes, it is necessary to have suitable two-photon fluorescent platforms. Herein, we present the rational design, synthesis, and spectral properties of carbazole–coumarin (CC) derivatives, a unique family of two-photon fluorescent dyes. Significantly, the action cross-sections of CC are tunable by modifications at the 4′-position of the coumarin moiety, implying that CC could be exploited as a novel platform to design two-photon fluorescent probes. Carbon monoxide (CO) plays an important role in many physiological and pathological processes. Although the tracking of CO in living cells has been previously reported, the detection of CO in much thicker biosamples, for instance, living tissues, has not been realized. It is known that two-photon fluorescent probes are favorable for monitoring biomolecules in living tissues. Thus, based on the unique CC platform, we rationally engineered CC–CO as the first two-photon fluorescent CO probe, and we further demonstrated that CC–CO could monitor the changes of CO levels not only in living cells but also in living tissues for the first time, demonstrating the value of our two-photon fluorescent CO probe. The CC platform is complementary to the current two-photon fluorescent platforms and it may be used to develop a wide variety of two-photon fluorescent probes. In addition, we expect that CC–CO and its next generation analogues may be useful for unraveling the functions of CO in complicated living systems.

Interaction between water molecules and 3C-SiC nanocrystal surface

The influence of water permeates almost all areas including biochemistry, chemistry, physics and is particularly evident in phenomena occurring at the interfaces of solid surface such as SiC nanocrystals, which are promising nanomaterials and exhibit unique surface chemical properties. In this paper, the quantum confinement effect and stability of 3C-SiC nanocrystals in aqueous solution as well as photoluminescence properties in water suspensions with different pH values are reviewed based on design and analysis of surface structures. On this basis, the significant progress of 3C-SiC nanocrystals in efficiently splitting water into usable hydrogen is summarized and the relative mechanisms are described. In addition, the water-soluble 3C-SiC quantum dots as robust and nontoxic biological probes and labels also are introduced as well as future prospects given.

Fabrication of a Smart Suspension Structure of Micro Tactile Probing

Abstract In micro tactile probing a design trade off must be made between stiff and robust probes. Stiff probes are capable of overcoming surface attraction forces, while delicate flexible probes are capable of making contact with a sensitive part without causing damage. To address this need for both flexible and stiff sensors a novel micro tactile probe has been proposed that makes use of an active suspension structure to modulate probe stiffness as required. In this paper we focus on the initial manufacturing process development of such a sensor. While initial design concepts were created with high precision machining techniques in mind, these are shown to have some fundamental limitations with respect to this specific application. Therefore a design for manufacture strategy was adopted and the structure of the initial design was modified such that it may be manufactured using a chemical etching based process. This paper presents the process followed to successfully adapt an initial sensor design for a chemical etching based manufacturing. Surface 3D microscopy was used to analyse the resulting structure, to demonstrate a significant improvement in device flatness. In addition Finite Element Analysis (COMSOL) was used to estimate the vertical and torsional frequency for the suspension structure which is compared with experimental measurements using a laser vibrometer to show good agreement.

PD-0036: Monte Carlo output correction factors for Cyberknife and Synergy small fields for the Exradin W1 Scintillator

Materials and Methods: The Exradin W1 Scintillator is a plastic scintillating fiber-based detector designed for highly accurate measurement of small radiotherapy fields. This new near-water equivalent plastic scintillation detector (PSD) is being manufactured by Standard Imaging, Inc. The Exradin W1 Scintillator sensitive element is composed of a plastic scintillating fiber enclosed inside a 2.8 mm diameter by 42 mm long water-equivalent robust housing probe. The dimensions of the plastic scintillating fiber (detector sensitive element) are 1.0 mm in diameter and 3.0 mm long. The physical density of the plastic scintillating fiber (PSD) is 1.05 g/cm. This PSD is optically coupled to a clear multi-clad optical fiber made of PMMA of a 1.0mm diameter core and 3 m in length protected with a 2.2 mm diameter polyethylene jacket. The scintillation light produced in the PSD is transmitted through this 3 m long optical fiber to a photodiode enclosed in a light tight small housing. The Monte Carlo method used to calculate

Robust high temperature sensor probe based on a Ni-coated fiber Bragg grating

A robust high temperature sensor probe based on a Ni-coated fiber Bragg grating(FBG) was fabricated by Ni electroplating of femtosecond laser written FBG. The probe can resist high temperature up to 800 oC with a high sensitivity of 32.2 pm/oC. It also has a good mechanical strength even after high temperature annealing. The thermal strain of the probe was simulated by the finite element method(FEM). The Bragg resonant wavelength shift with temperature and its sensitivity change with the thickness of the Ni-coated layer were also calculated. Keywords Fiber Bragg grating(FBG); Femtosecond laser; Electroplating

Methods for estimating acoustic intensity in rocket noise fields

The acoustic field produced by launch vehicles is difficult to measure and characterize. Acoustic intensity measurements provide more information per measurement location than pressure measurements and are therefore interesting for the characterization of rocket noise fields. The extreme environment associated with a rocket requires a robust intensity probe while the large size of the source and the high-amplitude, highly nonlinear behavior of the system produce a signal with significant low and high frequency components. Thus, the probe must also provide accurate results over a large frequency band. The bandwidth limitations of the standard method for estimating acoustic intensity, the p-p finite difference method, motivated the development of an alternative method for intensity estimation. The new phase and amplitude gradient estimation (PAGE) method will be presented and compared to the standard p-p method. Specific features of the rocket noise field that can be leveraged to improve the bandwidth of the intensity estimates will also be discussed.

Low energy probes of PeV scale sfermions

We derive bounds on squark and slepton masses in mini-split supersymmetry scenario using low energy experiments. In this setup gauginos are at the TeV scale, while sfermions are heavier by a loop factor. We cover the most sensitive low energy probes including electric dipole moments (EDMs), meson oscillations and charged lepton flavor violation (LFV) transitions. A leading log resummation of the large logs of gluino to sfermion mass ratio is performed. A sensitivity to PeV squark masses is obtained at present from kaon mixing measurements. A number of observables, including neutron EDMs, mu->e transitions and charmed meson mixing, will start probing sfermion masses in the 100 TeV-1000 TeV range with the projected improvements in the experimental sensitivities. We also discuss the implications of our results for a variety of models that address the flavor hierarchy of quarks and leptons. We find that EDM searches will be a robust probe of models in which fermion masses are generated radiatively, while LFV searches remain sensitive to simple-texture based flavor models.

Absorption signatures of warm-hot gas at low redshift: Ne viii

At z<1 a large fraction of the baryons is thought to reside in diffuse gas that has been shock-heated to high temperatures (log T=5-6). Absorption by the 770.41, 780.32 {\AA} doublet of NeVIII in quasar spectra represents a unique tool to study this elusive warm-hot phase. We have developed an analytic model for the properties of NeVIII absorbers that allows for an inhomogeneous metal distribution. Our model agrees with the predictions of a simulation from the OWLS project indicating that the average line-of-sight metal-filling fraction within the absorbing gas is low (c_L~0.1). Most of the NeVIII in our model is produced in low-density, collisionally ionized gas (log n=-6 to -4 cm^-3, log T=5-6). Strong NeVIII absorbers (log N(NeVIII)>14), like those recently detected by HST/COS, are found to arise in higher density gas (log n>-4, log T=5.75). NeVIII cloudlets harbour only 1 per cent of the cosmic baryon budget. The baryon content of the surrounding gas (which has similar densities and temperatures as the NeVIII cloudlets) is a factor 1/c_L higher. We conclude that NeVIII absorbers are robust probes of shock-heated diffuse gas, but that spectra with signal-to-noise ratios S/N>100 would be required to detect the bulk of the baryons in warm-hot gas.

Simultaneous Fluorescence Imaging of the Activities of DNases and 3′ Exonucleases in Living Cells with Chimeric Oligonucleotide Probes

Real-time fluorescence imaging of the activity of nucleases in living cells has been a difficult issue because of unintended degradation of the natural oligonucleotides by nontarget nucleases or interactions with other proteins. In this work, we demonstrate two types of highly selective, sensitive, and robust oligonucleotide probes for simultaneous imaging of the activities of two different nucleases in living cells. The probes consist of the desired substrate structure of the target nuclease and partially phosphorothioate modified backbone labeled with fluorophore and quencher for protection from undesired degradation by other nucleases and signal transduction. Upon reaction with the target nuclease, the initially fluorescence quenched probe was cleaved and the fluorophore was separated from the quencher, giving out strong fluorescence signals. Two nucleases, DNase I and Exonuclease III, were employed as model enzymes to demonstrate the concept. In vitro studies proved that the two probes could discriminate their respective target nucleases in serum with high resistance to other coexisting enzymes. The lower limits of detection for DNase I and Exonuclease III were observed to be 40 U/L and 2.0 U/L, respectively. By labeling the two probes with different fluorophores and quenchers, simultaneous visualization of the activities of DNases and 3' exonucleases was achieved in both HeLa cells and the suspension cells of Arabidopsis thaliana. The developed approaches may greatly facilitate the studies on the intracellular functions of the two nucleases and other related biological processes. The probe design concept may also be further adapted to the detection of many other nucleases.

Development of Innovative and Versatile Polythiol Probes for Use on ELOSA or Electrochemical Biosensors: Application in Hepatitis C Virus Genotyping

The aim of this study was to develop versatile diagnostic tools based on the use of innovative polythiolated probes for the detection of multiple viruses. This approach is compatible with optical enzyme-linked oligosorbent assay (ELOSA) or electrochemical (biosensors) detection methods. The application targeted here concerns the rapid genotyping of Hepatitis C virus (HCV). HCV genotyping is one of the predictive parameters currently used to define the antiviral treatment strategy and is based on the sequencing of the viral NS5b region. Generic and specific NS5b amplicons were produced by real-time polymease chain reaction (RT-PCR) on HCV(+) human plasma. Original NS5b probes were designed for genotypes 1a/1b, 2a/2b/2c, 3a, and 4a/4d. Robust polythiolated probes were anchored with good efficacy on maleimide-activated microplates (MAM) and gold electrodes. Their grafting on MAM greatly increased the sensitivity of the ELOSA test which was able to detect HCV amplicons with good sensitivity (10 nM) and specificity. Moreover, the direct and real-time electrochemical detection by differential pulse voltammetry enabled a detection limit of 10 fM to be reached with good reproducibility. These innovative polythiolated probes have allowed us to envisage developing flexible, highly sensitive, and easy-to-handle platforms dedicated to the rapid screening and genotyping of a wide range of viral agents.

Site-Specific Measurements of Lipid Membrane Interfacial Water Dynamics with Multidimensional Infrared Spectroscopy

One route to accessing site-specific dynamical information available with ultrafast multidimensional infrared spectroscopy is the development of robust and versatile vibrational probes. Here we synthesize and characterize a vibrationally labeled cholesterol derivative, (cholesteryl benzoate) chromium tricarbonyl, to probe model lipid membranes, focusing specifically on the membrane-water interface. Utilizing FTIR and polarized-ATR spectroscopies, we determine the location of the chromium tricarbonyl motif to be situated at the water-membrane interface with an orientation of 46 ± 2° relative to the vector normal to the membrane surface. We test the dynamical sensitivity of the (cholesteryl benzoate) chromium tricarbonyl label with two different nonlinear infrared spectroscopy methods, both of which show that the probe is well-suited to the study of membrane dynamics as well as the dynamics of water at the membrane interface. The metal carbonyl vibrational probe located at the surface of a bicelle exhibits spectral diffusion dynamics induced by membrane hydration water that is roughly three times slower than observed using a nearly identical vibrational probe in bulk water.

A robust, water-soluble and low cytotoxic fluorescent probe for sulfide anion achieved through incorporation of betaine

Sulfide anions are generated not only from industrial processes but also in biosystems. Hence, robust fluorescent sensors for sulfide which are fast-responding, water soluble and biocompatible are highly desirable. Herein, we report the first betaine-based fluorescent sensor, which features excellent water solubility, low cytotoxicity and short response time. This sensor is based on the chelator/Cu(II) approach so as to achieve fast sensing, in which tris(2-aminoethyl)amine is selected as the Cu(II) chelator since this tripodal chelator can strongly bind with Cu2+. Two sulfobetaine groups, which are utilized to achieve water solubility and biocompatibility, are incorporated onto the sensor. The fluorophore–chelator–Cu(II) complex functions as the sulfide sensor which exhibits very low fluorescence, and sulfide anion can extract Cu2+ from the sensor since sulfide anion can form very stable CuS with Cu(II), resulting in fluorescence enhancement. With two betaine groups and a tripodal chelator in its structure, the sensor exhibits excellent water solubility and low cytotoxicity, and is capable of permeating the cell membrane and realizing sulfide anion imaging in live cells. The sensor displays high selectivity and low detection limit of 1.1μM, and can be used for sulfide monitoring in such real sample as running water.

Cellular Delivery of Quantum Dot-Bound Hybridization Probe for Detection of Intracellular Pre-MicroRNA Using Chitosan/Poly(γ-Glutamic Acid) Complex as a Carrier

A quantum dot (QD)-bound hybridization probe was designed for detection of intracellular pre-miRNA using chitosan (CS)/poly(γ-glutamic acid) (γ-PGA) complex as a gene vector. The probe was prepared by assembling thiolated RNA to gold nanoparticle (Au NP) via Au-S bond and then binding 3′-end amine of the RNA to the carboxy group capped on quantum dot surface. The QD-RNA-Au NP probe was assembled on the vector by mixing with aqueous γ-PGA solution and then CS solution to construct a gene delivery system for highly effective cellular uptake and delivery. After the probe was released from CS/γ-PGA complex to the cytoplasm by electrostatic repulsion at intracellular pH, it hybridized with pre-miRNA precursor as target. The formed product was then cleaved by RNase III Dicer, leading to the separation of QDs from Au NPs and fluorescence emission of QDs, which could be detected by confocal microscopic imaging to monitor the amount of the intracellular pre-miRNA precursor. The in vitro assays revealed that the QD-RNA-Au NP was a robust, sensitive and selective probe for quantitative detection of target pre-miRNA. Using MDA-MB231 and MCF-7 breast cancer cells as models, the relative amount of pre-miRNA let-7a could be successfully compared. Since the amount of miRNA is related to the progress and prognosis of cancer, this strategy could be expected to hold promising application potential in medical research and clinical diagnostics.

Magnetic Near-Field Probes With High-Pass and Notch Filters for Electric Field Suppression

Several new types of low-cost and robust magnetic near-field probes manufactured in low-temperature co-fired ceramics (LTCC) are presented in this paper. Parallel C-shaped strips and their variations are inserted into the loop area in the front end of probes to achieve common-mode high-pass and notch filters for electric-field noise suppression. These probes with this kind of filter have excellent wideband electric field suppression. They are called high electric field suppression probes type A ~ D. The size of loop aperture in all probes is 100 μm long and 400 μm wide. The signal received from the loop is routed to a measurement apparatus through a semi-rigid coaxial cable with an outer diameter of 0.047 in. The flip-chip junction with low loss and good shielding is used between the probe head in LTCC and the semi-rigid coaxial cable. We take the probes over a 2000-μm-wide microstrip line as device-under-test to measure the probe characteristics. The isolation between electric and magnetic fields for a reference probe based on an old design using the same LTCC process is better than 30 dB from 0.05 to 12.65 GHz. The type A probe has two parallel C-shaped strips, it has better isolation of 35 dB from 0.1 to 11.05 GHz. Type C has one end of its strip shorted to ground, its 30-dB isolation frequency range can be extended to 0.05 ~ 17.8 GHz. With additional layout variation in type D, isolation can be improved to 40 dB up to 10.9 GHz. The spatial resolution for these probes is 140 μm when the distance between the metal surface of the microstrip line and the nearest edge of the loop is held at 120 μm. The calibration factors of the proposed probes are only slightly increased as compared with reference probe.

Photoelectron Spectroscopy of CdSe Nanocrystals in the Gas Phase: A Direct Measure of the Evanescent Electron Wave Function of Quantum Dots

We present the first photoelectron spectroscopy measurements of quantum dots (semiconductor nanocrystals) in the gas phase. By coupling a nanoparticle aerosol source to a femtosecond velocity map imaging photoelectron spectrometer, we apply robust gas-phase photoelectron spectroscopy techniques to colloidal quantum dots, which typically must be studied in a liquid solvent or while bound to a surface. Working with a flowing aerosol of quantum dots offers the additional advantages of providing fresh nanoparticles for each laser shot and removing perturbations from bonding with a surface or interactions with the solvent. In this work, we perform a two-photon photoionization experiment to show that the photoelectron yield per exciton depends on the physical size of the quantum dot, increasing for smaller dots. Next, using effective mass modeling we show that the extent to which the electron wave function of the exciton extends from the quantum dot, the so-called "evanescent electron wavefunction", increases as the size of the quantum dot decreases. We show that the photoelectron yield is dominated by the evanescent electron density due to quantum confinement effects, the difference in the density of states inside and outside of the quantum dots, and the angle-dependent transmission probability of electrons through the surface of the quantum dot. Therefore, the photoelectron yield directly reflects the fraction of evanescent electron wave function that extends outside of the quantum dot. This work shows that gas-phase photoelectron spectroscopy is a robust and general probe of the electronic structure of quantum dots, enabling the first direct measurements of the evanescent exciton wave function.

Whistle blast on private healthcare’s ‘zero sum game’

The newly strengthened Competition Commission says it will probably begin its long-awaited, robust probe into South Africa’s increasingly unaffordable private healthcare market towards the end of this year, with final recommendations and findings due out in late 2015.