Coherent population transfer between uncoupled or weakly coupled states in ladder-type superconducting qutrits

Stimulated Raman adiabatic passage offers significant advantages for coherent population transfer between uncoupled or weakly coupled states and has the potential of realizing efficient quantum gate, qubit entanglement and quantum information transfer. Here we report on the realization of the process in the superconducting Xmon and phase qutrits—two ladder-type three-level systems in which the ground state population is coherently transferred to the second excited state via the dark state subspace. We demonstrate that the population transfer efficiency is no less than 96% and 67% for the two devices, which agree well with the numerical simulation of the master equation. Population transfer via stimulated Raman adiabatic passage is significantly more robust against variations of the experimental parameters compared with that via the conventional resonant π pulse method. Our work opens up a new venue for exploring the process for quantum information processing using the superconducting artificial atoms.

Quantum state engineering necessitates transfer between quantum states. Here the authors demonstrate coherent population transfer between un- or weakly-coupled states of solid state systems, superconducting Xmon and phase qutrits, using stimulated Raman adiabatic passage and microwave driving.

Analysis of ROP signaling in the leaf epidermis of mutant tomato with low-energy ion beam

The importance of the ROP small GTPase signaling pathway in the regulation of cellular polarity growth in eukaryotes has been thoroughly studied. In this study, we examined the LeROP small GTPase (related to Arabidopsis thaliana genome LeROP GTPase in tomato) signaling of cell polarity growth in the mutant (M-1) tomato. Interestingly, we detected expansive growth of epidermis cells in M-1, in which the leaves appeared slightly lobed shaped. However, we observed jigsaw puzzle shaped and deeply lobed shaped leaves in wild-type leaf epidermis cells. The t-test showed significant difference (P < 0.05). Based on previous studies of the AtROP gene in Arabidopsis leaf epidermis cells, we hypothesized that the growth of mutant M-1 tomato leaf epidermis cell is related to AtROP gene signal transmission. The results of reverse transcription-polymerase chain reaction showed the expression of LeROP2, LeROP4, and LeROP7 in M-1 mutants were stronger than in wild-type cells. At the flowering stage, LeROP2 GTPase showed no expression in wild-type cells, but was expressed in mutant cells. This study revealed a link between the low-energy ion beam and the ROP GTPase signaling pathway in tomato. In addition, the ROP gene changes analyzed suggest a new mechanism for mutations following low-energy ion beam implantation.

Molecular basis of high-level ciprofloxacin resistance in Neisseria gonorrhoeae strains from Shandong Province, China

In the study, the ciprofloxacin resistance rate was 100%. High-level ciprofloxacin resistance rate was 63.55%. Sixteen different mutation patterns involved in the formation of ciprofloxacin resistance were identified. The most prevalent were patterns P7 (25.2%), P8 (15.0%), P9 (11.2%), P1 (10.3%), and P5 (10.3%). All of the 107 NG isolates analyzed for mutations in the study have demonstrated a change of Ser-91 → Phe in the gyrA gene, and all except one have demonstrated a change in position 95 of the amino acid sequence. All of the 68 high-level QRNG isolates had double mutations in gyrA gene combined with a single or two mutations in parC gene. It is most important that a new mutation site of Ile-97 → Met in gyrA and a new mutation of Leu-106 → Ile in parC were found in the study, both leading to high-level ciprofloxacin resistance (MIC values, 8 μg/mL, 32 μg/mL, respectively). Therefore, we confim that gyrA mutations are necessary for the fluoroquinolone resistance phenotype and parC mutations are correlated intimately with high-level fluoroquinolone resistance. In China fluoroquinolone resistance in Neisseria gonorrhoeae strains is very serious and the new mutation sites in the fluoroquinolone resistance-determining regions emerge more and more quickly. Hence, in China fluoroquinolones, which are used to treat gonorrhoea presently, should be substituted by a new antibiotics.

Wire network behavior in superconducting Nb films with diluted triangular arrays of holes

We present results of transport measurements on superconducting Nb films with diluted triangular arrays (honeycomb and kagomé) of holes. The patterned films have large disk-shaped interstitial regions even when the edge-to-edge separations between nearest neighboring holes are comparable to the coherence length. Changes in the field interval of two consecutive minima in the field dependent resistance R(H) curves are observed. In the low field region, fine structures in the R(H) and T(c)(H) curves are identified in both arrays. Comparison of experimental data with calculation results reveals that these structures observed in honeycomb and kagomé hole arrays resemble those in wire networks with triangular and T(3) symmetries, respectively. The findings suggest that even in these specified periodic hole arrays with very large interstitial regions, the low field fine structures are determined by the connectivity of the nanostructures.

A cryogen-free dilution refrigerator based Josephson qubit measurement system

We develop a small-signal measurement system on cryogen-free dilution refrigerator which is suitable for superconducting qubit studies. Cryogen-free refrigerators have several advantages such as less manpower for system operation and large sample space for experiment, but concern remains about whether the noise introduced by the coldhead can be made sufficiently low. In this work, we demonstrate some effective approaches of acoustic isolation to reduce the noise impact. The electronic circuit that includes the current, voltage, and microwave lines for qubit coherent state measurement is described. For the current and voltage lines designed to have a low pass of dc-100 kHz, we show that the measurements of Josephson junction's switching current distribution with a width down to 1 nA, and quantum coherent Rabi oscillation and Ramsey interference of the superconducting qubit can be successfully performed.

Quantum phase diffusion in a small underdamped Josephson junction

Quantum phase diffusion in a small underdamped Nb/AlO(x)/Nb junction (∼0.4 μm(2)) is demonstrated in a wide temperature range of 25-140 mK where macroscopic quantum tunneling (MQT) is the dominant escape mechanism. We propose a two-step transition model to describe the switching process in which the escape rate out of the potential well and the transition rate from phase diffusion to the running state are considered. The transition rate extracted from the experimental switching current distribution follows the predicted Arrhenius law in the thermal regime but is greatly enhanced when MQT becomes dominant.

Observation of macroscopic quantum tunneling in a single Bi2Sr2CaCu2O8+delta surface intrinsic Josephson junction

We report on the first unambiguous observation of macroscopic quantum tunneling (MQT) in a single submicron Bi(2)Sr(2)CaCu(2)O(8+delta) surface intrinsic Josephson junction (IJJ) by measuring its temperature-dependent switching current distribution. All relevant junction parameters were determined in situ in the classical regime and were used to predict the behavior of the IJJ in the quantum regime via MQT theory. Experimental results agree quantitatively with the theoretical predictions, thus confirming the MQT picture. Furthermore, the data also indicate that the surface IJJ, where the current flows along the c axis of the crystal, has the conventional sinphi current-phase relationship.

Genomic instability in phenotypically normal regenerants of medicinal plant Codonopsis lanceolata Benth. et Hook. f., as revealed by ISSR and RAPD markers

Codonopsis lanceolata Benth. et Hook. f., commonly known as bonnet bellflower, is a high-valued herb medicine and vegetable. In this study, a large number of plants were regenerated via organogenesis from immature seed-derived calli in C. lanceolata by a simple and efficient method. Compared with the mother donor plant, the regenerated plants did not exhibit visible phenotypic variations in six major morphological traits examined at the stage of one-season-maturity under field conditions. To gain insight into the genomic stability of these regenerated plants, 63 individuals were randomly tagged among a population of more than 2,000 regenerants, and were compared with the single mother donor plant by two molecular markers, the inter-simple sequence repeats (ISSR) and randomly amplified polymorphic DNA (RAPD). Apparent genomic variation was detected in the 63 regenerants, whereas preexisting heterozygosiy in the donor plant was deemed minimal by testing 30 seedlings germinated from selfed seeds of the same donor plant. The percentages of polymorphic bands (PPB) in the ISSR and RAPD analysis were respectively 15.7 and 24.9% for the 63 regenerated plants. Cluster analysis indicates that the genetic similarity values calculated on the basis of RAPD and ISSR data among the 64 plants (63 regenerated and one donor) were respectively 0.894 and 0.933, which allow classification of the plants into distinct groups. Nineteen randomly isolated bands underlying the changed RAPD or ISSR patterns were sequenced, and three of them showed significant homology to known-function genes. Detailed pairwise sequence comparison at one locus between the donor plant and a regenerant revealed that insertion of two short (24 and 19 bp) stretches of nucleotides in the regenerated plant relative to the donor plant occurred in an apparently stochastic manner.

Lack of effects of transforming growth factor-alpha gene knockout on peripheral nerve regeneration may result from compensatory mechanisms

Transforming growth factor-alpha (TGF-alpha), previously identified as a major member of the epidermal growth factor (EGF) family of growth factors, plays a role in proliferation, differentiation, and survival of neuronal and glial precursors and is implicated in development of the nervous system. However, its roles in nerve injury-induced responses remain obscure. The current study examined roles of endogenous TGF-alpha in peripheral nerve regeneration using sciatic nerve injury models with TGF-alpha knockout mice. Three weeks after a sciatic nerve crush, no significant differences were found between TGF-alpha wild-type and mutant mice in the number of retrogradely labeled L5 dorsal root ganglion (DRG) sensory neurons and L5 spinal cord motor neurons and in the morphology of myelinated regenerating nerve fibers, indicating that TGF-alpha is not essential for sensory and motor nerve regeneration. To assess a possible functional redundancy among TGF-alpha-related ligands in response to a nerve injury, mRNA expression of the EGF family was analyzed by RT-PCR in L4/L5 DRG pools and distal degenerating sciatic nerve segments after sciatic nerve ligation. Prior to and 1 day after ligation, there was a higher level of EGF-R mRNA in DRGs and in nerve in TGF-alpha null mice compared to wild types, and there was an induction of ligand amphiregulin mRNA in DRGs in mutant mice in place of the TGF-alpha upregulation present in wild types. These results indicate that TGF-alpha gene knockout does not affect peripheral nerve regeneration, probably due to a functional redundancy within the EGF family through a compensatory expression mechanism at both the receptor and ligand levels in TGF-alpha knockout mice.

Impairment of endothelial function after a high-fat meal in patients with coronary artery disease

OBJECTIVE

To determine the effect of postprandial lipid changes on endothelial function in patients with coronary artery disease (CAD) after a high-fat meal.

METHODS

We studied 50 CAD patients and 25 control participants, who were all normocholesterolemic. Flow-mediated vasodilatation of the brachial artery was evaluated by the high-resolution ultrasound technique before and after a single high-fat meal (800 calories; 50 g fat).

RESULTS

Postprandial serum triglyceride level increased significantly at 2-7 h and mean flow-mediated vasodilatation was impaired significantly (from 4.22 +/- 0.44 to 2.75 +/- 0.33%, P < 0.01) for 75 subjects. The increment in 2 h serum triglyceride level correlated positively with the decrement in postprandial flow-mediated vasodilatation (r = 0.459, P < 0.01). Postprandial triglyceride level was significantly higher in CAD patients than in control participants. Flow-mediated vasodilatation was significantly impaired in CAD patients (from 3.04 +/- 0.39 to 1.69 +/- 0.23%, P < 0.01) and control participants (from 6.58 +/- 0.52 to 4.87 +/- 0.19%, P < 0.05) after a high-fat meal. The impairment of flow-mediated dilatation was more severe in CAD patients (44.41%) than in control participants (25.99%, P < 0.01).

CONCLUSION

Postprandial endothelium-dependent vasodilatation after a single high-fat meal was severely impaired in normocholesterolemic CAD patients and control participants. The disordered postprandial metabolism of triglyceride-rich lipoproteins may play an atherogenic role by inducing endothelial dysfunction.

Microinvasive Nd:YAG laser therapy of early glottic carcinoma and its effect on soluble interleukin-2 receptor, interleukin-2, and natural killer cells

OBJECTIVE

To investigate the effectiveness of microinvasive Nd:YAG laser therapy in human glottic Tis and T1 carcinomas, as well as its effect on the cellular immune function of the tumor-bearing hosts.

STUDY DESIGN

We treated 34 patients with microinvasive Nd:YAG laser therapy and evaluated its effect on the cellular immune function of the host.

METHODS

Thirty-four patients with glottic Tis or T1 squamous cell carcinoma were treated with fiberoptic laryngoscopic Nd:YAG laser surgery. Both before and after therapy, serum levels of soluble interleukin-2 receptor (SIL-2R) and interleukin-2 (IL-2), as well as natural killer (NK) cell activity, were determined by means of double-antibody sandwich technique, tritiated thymidine-deoxyribonucleoside incorporation, and iodine 125-uridine-deoxyribonucleoside release technique, respectively.

RESULTS

All 34 patients tolerated the procedure well. A 3- to 7-year follow-up in a subgroup of 27 patients resulted in an estimated cure rate of 85.2% (23 of 27 patients). In all 27 patients with a regular follow-up, a subjective improvement of phonation was noted after therapy to various degrees. In 74% (20 of 27 patients), voice and speech subjectively recovered to almost normal levels. The post-therapy serum levels of SIL-2R were significantly declined (P <.001), whereas those of IL-2 and the NK activity were significantly elevated (P <.001) as compared with those detected before therapy.

CONCLUSIONS

Therapy with fiberoptic laryngoscopic Nd:YAG laser surgery is simple, safe, effective and only minimally invasive for patients with glottic Tis or T1 carcinoma. At the same time, it has an immunoenhancing effect on its host.

Captopril inhibits the production of tumor necrosis factor-alpha by human mononuclear cells in patients with congestive heart failure

To study the effects of captopril on tumor necrosis factor-alpha produced by peripheral blood mononuclear cells (PBMC) of patients with congestive heart failure (CHF), we determined the TNF-alpha concentrations of culture supernatants of PBMC with and without catopril in 74 CHF patients with various heart diseases. The results showed that the supernatants concentrations of TNF-alpha in cultured PBMC (PBMC-TNF-alpha) were significantly increased in non-cachetic and cachetic CHF patients, and even higher in cachetic CHF patients, as compared with the controls (i.e., patients with New York Heart Association CHF classification I). The PBMC-TNF-alpha was significantly inhibited by captopril. These results demonstrate that the expression of TNF-alpha in PBMC is increased and can be inhibited by captopril in patients with CHF, especially in those accompanied by cachexia. This suggests that the immunomodulatory effects of captopril may contribute to its beneficial effects in heart failure patients.

Effect of bisoprolol on QT dispersion in patients with congestive heart failure--the etiology-dependent response

AIMS

To evaluate the effect of beta1-selective blocker bisoprolol on the QT and QTc dispersion in patients with chronic heart failure and to compare the responses to bisoprolol in patients with different etiologies.

METHODS AND RESULTS

Eighty-one patients with heart failure secondary to ischemic heart disease (n=47) or idiopathic dilated cardiomyopathy (n=34) were stratified by etiology and then randomly assigned to the bisoprolol and control group (no tablet) on top of the conventional treatment. QT dispersion was calculated by subtracting the shortest QT from the longest QT, in absolute value (Qtmax-Qtmin). It was also corrected with Bazett's formula (QTc dispersion). After 6 weeks of treatment, QT and QTc dispersion were significantly decreased in the bisoprolol group (QT dispersion: 66.5+/-13.4 ms vs. 49.1+/-16.8 ms for ischemic heart disease (P<0.01); 67.5+/-12.4 ms vs. 59.4+/-14.4 ms for dilated cardiomyopathy (P<0.05); QTc dispersion: 78.3+/-15.2 ms vs. 53.3+/-18.1 ms for ischemic heart disease (P<0.01); 79.1+/-14.2 ms vs. 69.0+/-17.9 ms for dilated cardiomyopathy (P<0.05)), but there was no significant decrease of QT and QTc dispersion in the control group. Linear regression analysis showed that patients with ischemic heart disease tend to have lower 6-week QT dispersion than patients with dilated cardiomyopathy (coefficient beta=-0.283, P=0.009) after controlling for their baseline values in the bisoprolol group.

CONCLUSION

These findings suggested that bisoprolol reduces QT and QTc dispersion in patients with chronic heart failure, but the etiology of heart failure affects the response of patients to bisoprolol.

[Impairment effect of diabetes mellitus combined with hypertension on artery vasodilation]

OBJECTIVES

This study was to assess the relationship between endothelial dysfunction, and to explore smooth muscle dysfunction and the synergic action of different risk factors on impairment of artery vasodilation.

METHODS

Using high resolution ultrasound, the dilator response of the brachial artery to 500 micrograms of sublingual nitroglycerin (NTG) was measured in patients with Type 2 diabetes mellitus (Group 1), patients with hypertension (Group 2), patients with both Type 2 diabetes mellitus and hypertension (Group 3), and control subjects (Group 4). Blood pressure, total serum cholesterol, basic vessel size, and flow-mediated endothelium-dependent dilation (EDD) were also measured.

RESULTS

On multiple linear regression analysis, a reduced vasodilator response to NTG was positively correlative with reduced EDD(P < 0.001). EDD was reduced in Group 1 (P < 0.05), Group 2 (P < 0.01) and Group 3(P < 0.01) compared to Group 4, but only Group 3 showed significantly reduced dilator response to NTG(P < 0.00).

CONCLUSION

The impairment of vasodilator response to exogenous NO is associated with reduced EDD. More risk factors may aggravate impairment of vasodilation.

Oxidized lipoprotein(a) enhanced the expression of P-selectin in cultured human umbilical vein endothelial cells

Lipoprotein(a) [Lp(a)] has been demonstrated to be an independent risk factor for coronary heart disease. However, the precise mechanism by which it contributes to the development of atherosclerosis remains unclear. P-selectin is one of the major adhesion molecules to mediate the interaction between monocytes, platelets and endothelial cells. Increased expression of P-selectin has been frequently found in atherosclerotic lesions. The present study assessed the effects of native and oxidized LDL (n-LDL and ox-LDL) and Lp(a) (n-Lp(a) and ox-Lp(a)) on the expression of P-selectin in cultured human umbilical vein endothelial cells (HUVECs). Cell ELISA was used to measure the expression of P-selectin in HUVECs and monocyte adhesion assay was used to detect whether the P-selectin expressed in HUVECs was functional. P-selectin mRNA expression in HUVECs was determined by Northern blot. Results showed that P-selectin protein expression was not influenced by n-LDL, but was moderately increased by ox-LDL and n-Lp(a). ox-Lp(a) was the most potent stimulus for P-selectin expression, increasing it in HUVECs by 144 +/- 10% at 10 nmol/l and 202 +/- 22% at 20 nmol/l. In addition, it showed that dose dependency induced monocyte adherence to endothelial cells after incubation of HUVECs with ox-Lp(a). Northern blot analysis demonstrated that the amount of P-selectin mRNA was markedly increased after treatment with ox-Lp(a) but not with n-LDL, ox-LDL and n-Lp(a). These results demonstrate that ox-Lp(a) can induce P-selectin expression in HUVECs, which may thereby influence the pathogenesis of athersclerosis.

[MDM2 gene expression in nasopharyngeal carcinoma and its relationship with p53 protein expression and EB virus latent infection]

OBJECTIVE

To define the expression levels of MDM2 gene in nasopharyngeal carcinoma (NPC) and its relationship with p53 protein expression and EB virus latent infection.

METHOD

MDM2 gene expression at mRNA and protein levels, p53 protein and EB virus DNA were detected by nonradioactive in situ hybridization (ISH), immunohistochemistry(IHC) and polymerase chain reaction (PCR) separately in 46 cases of NPC tissues and 12 cases of chronic inflammation of nasopharyngeal epithelium (CINE).

RESULT

Fourteen cases of NPC showed MDM2 mRNA and protein overexpression, 38 cases were p53 protein positive, and 43 cases were EBV-DNA positive. Neither MDM2 nor p53 protein was expressed in any case of CINE. MDM2 expression was significantly related to p53 protein expression (P < 0.05), but not to EB virus latent infection in NPC.

CONCLUSION

MDM2 gene may play an important role in the pathogenesis of NPC through interacting with p53 protein.

[Variation of blood lipids and circulatory endocrine factors in patients with acute myocardial infarction]

OBJECTIVE

To observe the dynamic variations of blood lipids and circulatory endocrine factors in acute myocardial infarction(AMI) patients.

METHODS

We determined plasma levels of ET-1, ANP, insulin and serum lipids on the 1st, 3rd, 7th and 14th day in 41 patients with acute myocardial infarction.

RESULTS

The serum levels of TC, LDL-C obviously decreased from the 3rd to the 7th day, and gradually elevated on the 14th day. The serum level of TG elevated gradually and showed significant difference after one week. HDL-C had no significant difference. The levels of ET-1 and insulin increased to highest level on the 1st day and decreased gradually since then. However, ANP reached the highest value on the 3rd day, and decreased markedly in fourteen days later. On the 1st day, only the concentration of insulin was negatively related with serum levels of TC, LDL-C(r = -0.376, -0.388, respectively, P < 0.05). The concentrations of blood lipids weren't related with circulatory endocrine factors during other phases.

CONCLUSION

The primary characteristics of blood lipids dynamic variations are the decrement of TC, LDL-C and the increment of TG during acute phase of AMI. Meanwhile, the concentrations of ET-1, ANP and insulin present dynamic variations and may effect the metabolism of blood lipids through some cytokines.