Atomic Ionization by Scalar Dark Matter and Solar Scalars.

We calculate the cross sections of atomic ionization by absorption of scalar particles in the energy range from a few eV to 100 keV. We consider both nonrelativistic particles (dark matter candidates) and relativistic particles that may be produced inside the Sun. We provide numerical results for atoms relevant for direct dark matter searches (O, Na, Ar, Ca, Ge, I, Xe, W and Tl). We identify a crucial flaw in previous calculations and show that they overestimated the ionization cross sections by several orders of magnitude due to violation of the orthogonality of the bound and continuum electron wave functions. Using our computed cross sections, we interpret the recent data from the Xenon1T experiment, establishing the first direct bounds on coupling of scalars to electrons. We argue that the Xenon1T excess can be explained by the emission of scalars from the Sun. Although our finding is in a similar tension with astrophysical bounds as the solar axion hypothesis, we establish direct limits on scalar DM for the ∼1-10 keV mass range. We also update axio-ionization cross sections. Numerical data files are provided.

Quantum Network of Atom Clocks: A Possible Implementation with Neutral Atoms.

We propose a protocol for creating a fully entangled Greenberger-Horne-Zeilinger-type state of neutral atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze a possible realization of this scheme using neutral Yb ensembles.

Magnetic-dipole transitions in highly charged ions as a basis of ultraprecise optical clocks.

We evaluate the feasibility of using magnetic-dipole (M1) transitions in highly charged ions as a basis of an optical atomic clockwork of exceptional accuracy. We consider a range of possibilities, including M1 transitions between clock levels of the same fine-structure and hyperfine-structure manifolds. In highly charged ions these transitions lie in the optical part of the spectra and can be probed with lasers. The most direct advantage of our proposal comes from the low degeneracy of clock levels and the simplicity of atomic structure in combination with negligible quadrupolar shift. We demonstrate that such clocks can have projected fractional accuracies below the 10^{-20}-10^{-21} level for all common systematic effects, such as blackbody radiation, Zeeman, ac-Stark, and quadrupolar shifts.

Validation of the VBLaST peg transfer task: a first step toward an alternate training standard.

BACKGROUND: The FLS trainer lacks objective and automated assessments of laparoscopic performance and requires a large supply of relatively expensive consumables. Virtual reality simulation has a great potential as a training and assessment tool of laparoscopic skills and can overcome some limitations of the FLS trainer. This study was carried out to assess the value of our Virtual Basic Laparoscopic Surgical Trainer (VBLaST(©)) in the peg transfer task compared to the FLS trainer and its ability to differentiate performance between novice, intermediate, and expert groups. METHODS: Thirty subjects were divided into three groups: novices (PGY1-2, n = 10), intermediates (PGY3-4, n = 10), and experts (PGY5, surgical fellows and attendings, n = 10). All subjects performed ten trials of the peg transfer task on each simulator. Assessment of laparoscopic performance was based on FLS scoring while a questionnaire was used for subjective evaluation. RESULTS: The performance scores in the two simulators were correlated, though subjects performed significantly better in the FLS trainer. Experts performed better than novices only on the FLS trainer while no significant differences were observed between the other groups. Moreover, a significant learning effect was found on both trainers, with a greater improvement of performance on the VBLaST(©). Finally, 82.6% of the subjects preferred the FLS over the VBLaST(©) for surgical training which could be attributed to the novelty of the VR technology and existing deficiencies of the user interface for the VBLaST(©). CONCLUSION: This study demonstrated that the VBLaST(©) reproduced faithfully some aspects of the FLS peg transfer task (such as color, size, and shape of the peg board, etc.) while other aspects require additional development. Future improvement of the user interface and haptic feedback will enhance the value of the system as an alternative to the FLS as the standard training tool for laparoscopic surgery skills.

Single-ion nuclear clock for metrology at the 19th decimal place.

The 7.6(5) eV nuclear magnetic-dipole transition in a single 229Th3+ ion may provide the foundation for an optical clock of superb accuracy. A virtual clock transition composed of stretched states within the 5F(5/2) electronic ground level of both nuclear ground and isomeric manifolds is proposed. It is shown to offer unprecedented systematic shift suppression, allowing for clock performance with a total fractional inaccuracy approaching 1×10(-19).

Effect of haptic feedback in laparoscopic surgery skill acquisition.

BACKGROUND: The benefits of haptic feedback in laparoscopic surgery training simulators is a topic of debate in the literature. It is hypothesized that novice surgeons may not benefit from the haptic information, especially during the initial phase of learning a new task. Therefore, provision of haptic feedback to novice trainees in the early stage of training may be distracting and detrimental to learning. A controlled experiment was conducted to examine the effect of haptic feedback on the learning curve of a complex laparoscopic suturing and knot-tying task. METHODS: The ProMIS and the MIST-VR surgical simulators were used to represent conditions with and without haptic feedback, respectively. A total of 20 novice subjects (10 per simulator) were trained to perform suturing and knot-tying and practiced the tasks in 18 sessions of 1 h each. RESULTS: At the end of the 3-week training period, the subjects performed equally fast but more consistently with haptics (ProMIS) than without haptics (MIST-VR). The subjects showed a slightly higher learning rate and reached the first plateau of the learning curve earlier with haptic feedback. CONCLUSION: In general, learning with haptic feedback was significantly better than learning without it for a laparoscopic suturing and knot-tying task, but only during the first 5 h of training. Haptic feedback may not be warranted in laparoscopic surgical trainers. The benefits of a shorter time to the first performance plateau and more consistent initial performance should be balanced with the cost of implementing haptic feedback in surgical simulators.

Differential light-shift cancellation in a magnetic-field-insensitive transition of 87rb.

The precise measurement of transition frequencies of trapped atomic samples is susceptible to inaccuracy arising from the inhomogeneous differential shift of the relevant energy levels in the presence of the trapping fields. We demonstrate near-complete cancellation of the differential ac Stark shift ("light shift") of a two-photon magnetic-field-insensitive microwave hyperfine (clock) transition in ^{87}Rb atoms trapped in an optical lattice. Up to 95(2)% of the differential light shift is cancelled while maintaining magnetic-field insensitivity. This technique should have applications in quantum information and frequency metrology.

[Photodynamic therapy in treatment of lung cancer].

The effectiveness of photodynamic therapy was studied in 20 patients with different stages of lung cancer. We used the photosensitizer--PHOTOHEM and gold vapor laser (Auran). Photodynamic therapy was combined with high-energy laser photodestruction of tumors in 7 patients. In late (IIIb and IV) cancers the application of photodynamic therapy has significantly reduced the tumor tissue of bronchial obstruction in 9 out of 12 (75%) patients with improvement of the respiratory function, disappearance of atelectases. Photodynamic therapy was less effective in bronchoscopic signs of infiltrative tumor growth, typical for its peribronchial form. In the early stages of cancer the application of photodynamic therapy allowed complete removal of the tumor. However, 2 out of 8 patients showed signs of residual tumor growth within 1-3 months which disappeared due to repeated treatments with photodynamic therapy.

Mapping out atom-wall interaction with atomic clocks.

We explore the feasibility of probing atom-wall interaction with atomic clocks based on atoms trapped in engineered optical lattices. Optical lattice is normal to the wall. By monitoring the wall-induced clock shift at individual wells of the lattice, one would measure the dependence of the atom-wall interaction on the atom-wall separation. We find that the induced clock shifts are large and observable at already experimentally demonstrated levels of accuracy. We show that this scheme may uniquely probe the long-range atom-wall interaction in all three qualitatively distinct regimes of the interaction: van der Waals (image-charge interaction), Casimir-Polder (QED vacuum fluctuations), and Lifshitz (thermal-bath fluctuations) regimes.

Precision determination of electroweak coupling from atomic parity violation and implications for particle physics.

We carry out high-precision calculation of parity violation in a cesium atom, reducing theoretical uncertainty by a factor of 2 compared to previous evaluations. We combine previous measurements with calculations and extract the weak charge of the 133Cs nucleus, QW=-73.16(29)expt(20)theor. The result is in agreement with the standard model (SM) of elementary particles. This is the most accurate to-date test of the low-energy electroweak sector of the SM. In combination with the results of high-energy collider experiments, we confirm the energy dependence (or "running") of the electroweak force over an energy range spanning 4 orders of magnitude (from approximately 10 MeV to approximately 100 GeV). Additionally, our result places constraints on a variety of new physics scenarios beyond the SM. In particular, we increase the lower limit on the masses of extra Z bosons predicted by models of grand unification and string theories.

Micromagic clock: microwave clock based on atoms in an engineered optical lattice.

We propose a new class of atomic microwave clocks based on the hyperfine transitions in the ground state of aluminum or gallium atoms trapped in optical lattices. For such elements magic wavelengths exist at which both levels of the hyperfine doublet are shifted at the same rate by the lattice laser field, cancelling its effect on the clock transition. A similar mechanism for the magic wavelengths may work in microwave hyperfine transitions in other atoms which have the fine-structure multiplets in the ground state.

Magic frequencies for cesium primary-frequency standard.

We consider microwave hyperfine transitions in the ground state of cesium and rubidium atoms which are presently used as the primary and the secondary frequency standards. The atoms are confined in an optical lattice generated by a circularly polarized laser field. We demonstrate that applying an external magnetic field with appropriately chosen direction may cancel dynamic Stark frequency shift making the frequency of the clock transition insensitive to the strengths of both the laser and the magnetic fields. This can be attained for practically any laser frequency which is sufficiently distant from a resonance.

[Transbronchial biopsy of the lungs in diagnosis of respiratory sarcoidosis].

AIM: To specify diagnostic potentialities of transbronchial biopsy of the lungs (TBB) in respiratory sarcoidosis (RS). MATERIAL AND METHODS: TBB of the lungs was performed in bronchofibroscopy under local anesthesia and TV x-ray control with intake of 4-5 biopsy specimens. RESULTS: Biopsy specimens consisted primarily of alveolar tissue in 62.5% patients, of bronchial wall - in 34.8%, were insufficiently informative - in 2.4% patients. Histological examination of the biopsies detected sarcoid granulemas which served the basis for RS diagnosis in 62.5% patients (stage 1 - 51.1%, stage 2 - 70.4%, stage 3 - in 61.6%). Sarcoid granulemas were detected more frequently in alveolar tissue than in bronchial walls (75.3 and 38.5%, respectively, p < 0.05). In RS stage 1 granulemas in the bronchial walls were found less often than in stages 2 and 3 (56.3, 42.9%, respectively, p < 0.01). CONCLUSION: TBB provides morphological RS diagnosis in 2/3 patients and is a safe method. Obtaining biopsies containing alveolar tissue raises efficacy of TBB, especially in the disease stage 1.

Trapping of neutral mercury atoms and prospects for optical lattice clocks.

We report vapor-cell magneto-optical trapping of Hg isotopes on the (1)S(0)-(3)P(1) intercombination transition. Six abundant isotopes, including four bosons and two fermions, were trapped. Hg is the heaviest nonradioactive atom trapped so far, which enables sensitive atomic searches for "new physics" beyond the standard model. We propose an accurate optical lattice clock based on Hg and evaluate its systematic accuracy to be better than 10;{-18}. Highly accurate and stable Hg-based clocks will provide a new avenue for the research of optical lattice clocks and the time variation of the fine-structure constant.

High-accuracy calculation of the blackbody radiation shift in the 133Cs primary frequency standard.

The blackbody radiation (BBR) shift is an important systematic correction for the atomic frequency standards realizing the SI unit of time. Presently, there is controversy over the value of the BBR shift for the primary 133Cs standard. At room temperatures, the values from various groups differ at the 3x10(-15) level, while modern clocks are aiming at 10(-16) accuracies. We carry out high-precision relativistic many-body calculations of the BBR shift. For the BBR coefficient beta at T=300 K, we obtain beta=-(1.710+/-0.006)x10(-14), implying 6x10(-17) fractional uncertainty. While in accord with the most accurate measurement, our 0.35% accurate value is in a substantial (10%) disagreement with recent semiempirical calculations. We identify an oversight in those calculations.

Electric-octupole and pure-electric-quadrupole effects in soft-X-Ray photoemission

Second-order [ O(k(2)), k = omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and a theoretical study of angular distributions of neon valence photoelectrons in the 100-1200 eV photon-energy range. A newly derived theoretical expression for nondipolar angular distributions characterizes the second-order effects using four new parameters with primary contributions from pure-quadrupole and octupole-dipole interference terms. Independent-particle calculations of these parameters account for a significant portion of the existing discrepancy between experiment and theory for Ne 2p first-order nondipole parameters.

Reconciliation of the measurement of parity nonconservation in Cs with the standard model

Contributions from the Breit interaction in atomic structure calculations account for 1.3sigma of the previously reported 2. 5sigma deviation from the standard model in the 133Cs weak charge [S. C. Bennett and C. E. Wieman, Phys. Rev. Lett. 82, 2484 (1999)]. The updated corrections for the neutron distribution reduce the discrepancy further to 1.0sigma. The updated value of the weak charge is Q(W)(133Cs) = -72.65(28)(expt)(34)(theor).

The role of neutrophil-derived oxidants as second messengers in interleukin 1beta-stimulated cells.

The role of the inflammatory cytokine interleukin 1beta (IL-1beta) as potent agonist of the PMN respiratory burst signal transduction cascade has been described. We hypothesized that this phenomenon is self-limiting and that polymorphonuclear leukocyte (PMN)-derived reactive oxygen intermediates (ROI) might provide feedback regulation on the IL-1beta surface receptor (IL-1betaR)-G-protein-effector enzyme transducing tripartite complex that ultimately leads to NADPH oxidase activation. Therefore, we separately assessed either baseline or IL-1beta-induced activation of each member of the IL-1betaR-G-protein-phospholipase D (PLD) or IL-1betaR-G-protein-phospholipase C (PLC) signaling systems in the presence or absence of one of several specific ROI scavengers/antioxidants. Purified human PMN were lipopolysaccharide primed, adhered for 2 h, and stimulated with 100 ng/mL IL-1beta with or without 1% v/v dimethyl sulfoxide, 10 mM NaN3, 30 mM L-alanine, 200 U catalase, or 300 U superoxide dismutase (SOD). To validate the use of these antioxidants, the production of O2-, H2O2, hypochlorous acid, or myeloperoxidase (MPO) in the employed experimental model was confirmed in a separate set of experiments. The expression of IL-1betaR type I or II was assessed by binding with corresponding 125I-labeled monoclonal antibodies and corrected for nonspecific binding. PLD activation was assessed by measuring phosphatidyl ethanol formation in the presence of ethanol. PLC activation was determined by quantitative measurement of diacylglycerol. The level of Galpha stimulatory and inhibitory subunits was assessed by Western blotting. IL-1betaR type I expression was significantly up-regulated in the presence of catalase and SOD. PLD activation was increased by dimethyl sulfoxide and NaN3, and PLC activation was up-regulated by NaN3, L-alanine, SOD, and catalase. After 5 min of stimulation with IL-1beta, Gialpha expression was significantly down-regulated by NaN3 and SOD, whereas SOD had an up-regulating effect on the expression of Gs alpha. Increasing concentrations of externally added authentic MPO progressively down-regulated both PLD and PLC activity. Thus, PMN-derived ROI, in addition to their role as antibacterial/fungal agents, serve as second messengers in IL-1beta signal transduction, with MPO having the most ubiquitous role as a modulator of PMN second messenger pathways.

Endogenous PMN-derived reactive oxygen intermediates provide feedback regulation on respiratory burst signal transduction.

The role of polymorphonuclear leukocytes (PMN) in stemming systemic infection is executed mainly by the utilization of molecular O2 leading to the production of reactive oxygen intermediates (ROI). PMN-derived ROI also serve as intra- and extracellular second messengers providing both positive and negative feedback on cellular autoregulation. We investigated the effect of endogenous ROI on two signal transducing pathways: the receptor (R)-G-protein-phospholipase D (PLD) and receptor (R)-G-protein-phospholipase C pathways responsible for the subsequent interleukin-8 (IL-8)-induced PMN respiratory burst. Purified human PMN were primed with LPS adhered to plastic surfaces and stimulated with IL-8 with or without the presence of each of five different selective ROI scavengers/antioxidants: DMSO, N(a)N3, L-alanine, catalase, or superoxide dismutase. Total IL-8 surface receptor expression was assessed by 125I-IL-8 and 125I-labeled mAbs against IL-8R type A and B binding assays; PLD activation was assessed by measuring formation of phosphatidyl ethanol (PEt) in the presence of ethanol; PLC activation was measured by quantitative conversion of [32P]ATP-labeled phosphatidic acid (PA) into diacylglycerol (DAG); expression of G alpha-inhibitory subunit was assessed by SDS-PAGE and immunoblotting with polyclonal Abs against this subunit. Production of O2-, H2O2, HClO, and myeloperoxidase (MPO) in the experimental model was confirmed in a separate set of experiments. The overall impact of antioxidants on each component of the transducing tripartite complex was stimulatory; however, N(a)N3 and SOD exhibited the most ubiquitous effect with consistent up-regulation by N(a)N3 of IL-8R expression, whereas even trace amounts of externally added authentic MPO significantly down-regulated the functional activity of both effector enzymes. These results demonstrate a multiple site-specific targeting of the signal-transducing complex by endogenous PMN-derived ROI and an overall protective effect of ROI scavengers/antioxidants.