Quantum-enhanced greedy combinatorial optimization solver.

Combinatorial optimization is a broadly attractive area for potential quantum advantage, but no quantum algorithm has yet made the leap. Noise in quantum hardware remains a challenge, and more sophisticated quantum-classical algorithms are required to bolster their performance. Here, we introduce an iterative quantum heuristic optimization algorithm to solve combinatorial optimization problems. The quantum algorithm reduces to a classical greedy algorithm in the presence of strong noise. We implement the quantum algorithm on a programmable superconducting quantum system using up to 72 qubits for solving paradigmatic Sherrington-Kirkpatrick Ising spin glass problems. We find the quantum algorithm systematically outperforms its classical greedy counterpart, signaling a quantum enhancement. Moreover, we observe an absolute performance comparable with a state-of-the-art semidefinite programming method. Classical simulations of the algorithm illustrate that a key challenge to reaching quantum advantage remains improving the quantum device characteristics.

Scaling advantage over path-integral Monte Carlo in quantum simulation of geometrically frustrated magnets.

The promise of quantum computing lies in harnessing programmable quantum devices for practical applications such as efficient simulation of quantum materials and condensed matter systems. One important task is the simulation of geometrically frustrated magnets in which topological phenomena can emerge from competition between quantum and thermal fluctuations. Here we report on experimental observations of equilibration in such simulations, measured on up to 1440 qubits with microsecond resolution. By initializing the system in a state with topological obstruction, we observe quantum annealing (QA) equilibration timescales in excess of one microsecond. Measurements indicate a dynamical advantage in the quantum simulation compared with spatially local update dynamics of path-integral Monte Carlo (PIMC). The advantage increases with both system size and inverse temperature, exceeding a million-fold speedup over an efficient CPU implementation. PIMC is a leading classical method for such simulations, and a scaling advantage of this type was recently shown to be impossible in certain restricted settings. This is therefore an important piece of experimental evidence that PIMC does not simulate QA dynamics even for sign-problem-free Hamiltonians, and that near-term quantum devices can be used to accelerate computational tasks of practical relevance.

Ointment tacrolimus for steroid resistant adenoviral nummular keratitis.

A 33-year-old man presented with a four-day history of redness and blurring of vision of the right eye. A clinical diagnosis of adenoviral keratitis was made with a differential of microsporidia epithelial keratitis. The patient subsequently developed nummular keratitis which was resistant to topical steroids. He continued to develop multiple recurrences of the condition. Treatment with tacrolimus ointment was started as the patient had an elevated intraocular pressure due to prolonged steroid use. Tacrolimus ointment showed a favourable outcome in the management of recurrent nummular keratitis.

Immunohistochemistry in the evaluation of neovascularization in tumor xenografts.

Angiogenesis, or neovascularization, is known to play an important role in the neoplastic progression leading to metastasis. CD31 or Factor VIII-related antigen (F VIII RAg) immunohistochemistry is widely used in experimental studies for quantifying tumor neovascularization in immunocompromised animal models implanted with transformed human cell lines. Quantification, however, can be affected by variations in the methodology used to measure vascularization including antibody selection, antigen retrieval (AR) pretreatment, and evaluation techniques. To examine this further, we investigated the microvessel density (MVD) and the intensity of microvascular staining among five different human tumor xenografts and a mouse syngeneic tumor using anti-CD31 and F VIII RAg immunohistochemical staining. Different AR methods also were evaluated. Maximal retrieval of CD31 was achieved using 0.5 M Tris (pH 10) buffer, while maximum retrieval of F VIII RAg was achieved using 0.05% pepsin treatment of tissue sections. For each optimized retrieval condition, anti-CD31 highlighted small vessels better than F VIII RAg. Furthermore, the MVD of CD31 was significantly greater than that of F VIII RAg decorated vessels (p<0.001). The choice of antibody and AR method has a significant affect on immunohistochemical findings when studying angiogenesis. One also must use caution when comparing studies in the literature that use different techniques and reagents.

Cellular mechanism of thymic involution.

Involution of the thymus and alterations in the development of thymocytes are the most prominent features of age-related immune senescence. We have carried out a comparative analysis of thymocyte and stroma in rapid thymic involution DBA/2 (D2) strain of mice compared with slow involution C57BL/6 (B6) strain of mice. Analysis of mice at 15 months of age suggested an age-related decrease in the thymocyte cell count, a block in the development of T cells and cortical involution in D2 mice compared with 3-month-old mice. TUNEL (terminal-deoxynucleotidyl-transferase-mediated dUTP-digoxigenin nick end labelling) staining and fluorescence-activated cell sorter (FACS) analysis showed that there was a significant increase in apoptotic cells in the cortex region of thymus in 15-month-old D2 mice compared with the same aged B6 mice. The thymocyte proliferation rate, as assessed by bromodeoxyuridine (BrdU) staining and [3H]-thymidine incorporation assay, was lower in 3-month-old D2 mice compared with the same age B6 mice. Immunohistochemical staining showed that the arrangement of MTS (mouse thymus stromal)-10+ epithelial cells and MTS-16+ connective tissue staining pattern had become disorganized in 15-month-old D2 mice but remained intact in B6 mice of the same age. These results suggest that, in D2 mice, both the thymocytes and stromal cells exhibit age-related defects, and that the genetic background of mice plays an important role in determining age-related alterations in thymic involution.

Quantification of tartrate resistant acid phosphatase distribution in mouse tibiae using image analysis.

Tartrate resistant acid phosphatase (TRAP) activity of bone is a suitable biochemical marker for osteoclastic bone resorption. Qualitatively, the histochemical distribution of TRAP has been used to identify osteoclasts responsible for bone resorption; however, there have been few attempts to quantify TRAP localization. We describe a method for evaluating bone resorption by quantifying area percentages of positive TRAP localization using image analysis. Mouse tibiae were paraffin embedded following demineralization in disodium ethylenediamine tetraacetic acid. Longitudinal sections of tibia were cut from 15 levels in the left and the right limbs of six mice (180 sections total) and stained for TRAP distribution. Positive TRAP localization was quantified by pixel area count and reported as a percentage of the total tissue area specified. The 1.85 mm2 region of interest was placed at the midpoint of the epiphyseal growth plate containing the provisional calcification layer and the primary spongiosa, while excluding cortical bone of each mouse tibia. The percentage of TRAP localization ranged from 0.95 to 1.31% and was not significantly different from level to level or limb to limb in each mouse (p > 0.100). Within the same region of interest, an osteoclast count along the bone perimeter also was performed. We demonstrated a strong correlation (r2 = 0.903) between the conventional histomorphometric osteoclast index and positive TRAP localization, validating the latter as an alternative method to assess bone resorption. Quantitative analysis of TRAP is significant because it allows statistical comparisons between treatment groups, promotes precise pathological diagnoses and facilitates a reference data base that may aid the study of bone related diseases involving increased bone resorption.

Linguistic analysis of the speech output of schizophrenic, bipolar, and depressive patients.

Using speech samples of 100 patients suffering from schizophrenia, bipolar illness and major depression, we addressed the question of the extent to which the linguistic abnormalities in the speech of these patients represent diagnosis-specific characteristics or constitute independent, syndrome-like dimensions of the illnesses. All speech samples were transcribed by a professional linguist who was blind to both identity and diagnosis of the patients. The majority of the deviant linguistic variables was found to be common to all three diagnostic groups under comparison, while only a few linguistic variables exhibited statistically significant between-group differences. On the other hand, when the respective variables were analysed as a multivariate entity, the variety of subtle between-group differences allowed us to discriminate between the diagnostic groups at an overall performance of 72.7% correctly classified patients. There was an almost complete lack of association between linguistic abnormalities and psychopathology syndromes. In particular, we found no correlation between the syndrome 'formal thought disorder' and the large variety of linguistic variables used in this investigation. In consequence, we conjecture that linguistically deviant speech characteristics represent an independent syndrome complex manifested at varying intensities across mental illnesses, and that this syndrome complex deserves greater attention, not only with respect to the principal understanding of the underlying disturbances, but also as a potential target of therapeutical intervention.

Effect of medroxyprogesterone pretreatment on pentagastrin-induced panic symptoms in females with panic disorder.

Clinical observation, as well as epidemiological and research data, suggest that female gonadal hormones influence the course of panic disorder (PD). Panicogenic agents such as pentagastrin are useful tools with which to study the pathophysiology of panic attacks. Nine women with PD were randomly assigned to receive, in a crossover design, a 3-day pretreatment with medroxyprogesterone acetate (MP) prior to an injection of pentagastrin, and a 3-day pretreatment with a placebo prior to another injection of pentagastrin. The panic response and the anxiety response to pentagastrin were decreased after MP pretreatment. These preliminary results support the use of laboratory models for investigations of the interactions between progestins and anxiety.

Response to flumazenil in women with premenstrual dysphoric disorder.

OBJECTIVE: The authors sought to determine whether the administration of flumazenil would induce marked panic symptoms in women suffering from premenstrual dysphoric disorder. METHOD: Ten women with premenstrual dysphoric disorder and 11 comparison subjects were injected with flumazenil or placebo in a double-blind, randomized, balanced crossover design in a single session in the luteal phase of their menstrual cycles. RESULTS: Flumazenil induced a much greater panic response in the women with premenstrual dysphoric disorder than in the comparison subjects. CONCLUSIONS: These preliminary results are consistent with a dysregulation of the g-aminobutyric acid A/benzodiazepine receptor complex during the premenstruum of women suffering from premenstrual dysphoric disorder.

Distinguishing between new and slightly worn underwear: a case study.

This case study relates to a suspect accused of shop-lifting a pair of underwear briefs from a department store. The report presents a method that was used to distinguish between new and used underwear employing both laser examination for biological staining and microscopical examination for thread wear.

The determination of paraquat.

Methods for the determination of paraquat are reviewed. Procedures are described in detail for the determination of paraquat in diverse materials such as food stuffs, body fluids, and water. The recommended procedures include visual spot test, spectrophotometric, gas chromatographic, and high performance liquid chromatographic techniques.

An indirect atomic-absorption method for the determination of selenium.

Because of the difficulty in determining selenium directly, an indirect atomic-absorption method has been developed, based on two selective reactions that lead to the formation of the Pd(DanSe)(2)Cl(2) complex and measurement of the palladium absorption. Reaction conditions, separation techniques, effect of foreign ions, instrumental conditions and sample analysis in the sub-ppm range are described. The method is more sensitive than existing atomic-absorption methods for selenium.

Naphtho[2,3-d]-2-selena-l,3-diazole as a reagent for the determination of macro to submicro quantities of palladium.

Five analytical procedures, gravimetric, spectrophotometric, radiometric, fluorometric and atomic-absorption, have been developed for the determination of macro to submicro amounts of palladium. The methods are based on the reaction of PdCl(2), with naphtho[2,3-d]-2-selena-l,3-diazole. Analytical conditions such as the reaction time, concentration ranges, effect of pH and of 68 foreign ions, and solvent extraction were studied. Information relating to the structure and formula of palladium-piazselenol reaction products is included.