A programmable two-qubit quantum processor in silicon.

Now that it is possible to achieve measurement and control fidelities for individual quantum bits (qubits) above the threshold for fault tolerance, attention is moving towards the difficult task of scaling up the number of physical qubits to the large numbers that are needed for fault-tolerant quantum computing. In this context, quantum-dot-based spin qubits could have substantial advantages over other types of qubit owing to their potential for all-electrical operation and ability to be integrated at high density onto an industrial platform. Initialization, readout and single- and two-qubit gates have been demonstrated in various quantum-dot-based qubit representations. However, as seen with small-scale demonstrations of quantum computers using other types of qubit, combining these elements leads to challenges related to qubit crosstalk, state leakage, calibration and control hardware. Here we overcome these challenges by using carefully designed control techniques to demonstrate a programmable two-qubit quantum processor in a silicon device that can perform the Deutsch-Josza algorithm and the Grover search algorithm-canonical examples of quantum algorithms that outperform their classical analogues. We characterize the entanglement in our processor by using quantum-state tomography of Bell states, measuring state fidelities of 85-89 per cent and concurrences of 73-82 per cent. These results pave the way for larger-scale quantum computers that use spins confined to quantum dots.

Role of prostatic fluid in cooled canine epididymal sperm.

In this study, sperms collected from the right and left cauda epididymis were grouped into having canine prostatic fluid (PF) sensitization or not diluted with egg yolk Tris-fructose citrate extender, and stored at 4°C. The necessity of canine PF in cooled preservation was determined by elucidating the sperm quality after the storage. As a result, while there was no difference among all groups up to 48 hr of storage, after storage for 96 hr and more, a significantly lower sperm motility was observed in the group without being sensitized to PF than the groups with being sensitized to PF (p < .05, p < .01). Although sperm abnormality increased in all groups with increased storage time, the group without being sensitized to PF showed significantly higher sperm abnormality than did the groups with being sensitized to PF after storage for 24 hr and more (p < .01). From these findings, we concluded that PF was necessary for the cooled preservation of the canine sperm because these sperms were protected from any effects of low temperatures by being sensitized to PF.

Malignant Oestrogen-producing Teratoma in a Cat.

A 5-year-old female domestic shorthair cat was presented with abdominal distension and serum biochemical evaluation indicated a high concentration of oestradiol (32.81 pg/ml). Exploratory laparotomy revealed a large cystic mass in the right ovary with cystic fluid containing a high level of oestradiol (18.80 pg/ml). The tumour was composed of immature neuroectodermal tissue, mature cartilage, smooth muscle, adipose tissue and aggregated, poorly differentiated mesenchymal cells. It contained cysts of various sizes that were lined by epithelium of different types. The basal layer of the lining epithelium was shown to express aromatase by immunohistochemistry. The findings suggest that this was a novel, malignant, oestrogen-secreting teratoma and that the aromatase-positive, neoplastic cells may have been the source of elevated levels of serum oestrogen.

Second-Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot.

We demonstrate coherent driving of a single electron spin using second-harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second-harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude, and the periodicity with respect to the phase of the drive is twice that of the fundamental harmonic. The maximum Rabi frequency observed for the second harmonic is just a factor of 2 lower than that achieved for the first harmonic when driving at the same power. Combined with the lower demands on microwave circuitry when operating at half the qubit frequency, these observations indicate that second-harmonic driving can be a useful technique for future quantum computation architectures.

GERMPLASM BANKING AND ITS ROLE IN THE DEVELOPMENT OF THE FISH GENETIC IMPROVEMENT PROGRAMME IN BRAZIL.

BACKGROUND: Over the last ten years, Brazilian fish farming has become more focused, resulting in the development of genetic improvement programmes (GIP) for two South American species Colossoma macropomum (tambaqui) and Pseudoplatystoma reticulatum (cachara). OBJECTIVE: To describe the action plan used for setting up the GIP and to detail the germplasm bank composition. MATERIALS AND METHODS: Semen of both species was collected, frozen and transported between locations in Brazil. To start the programme, full and half-sib families of both species were established from 120 males and 60 females. RESULTS: New species-specific protocols for semen cryopreservation s were established of value to commercial application in fish farming. CONCLUSION: Germplasm banking has enabled the exchange of biological material and reduced the overall GIP costs. Germplasm banking can be very important to the dissemination of the selected genetic material of these species among fish farmers.

Efficacy of low-dose human chorionic gonadotropin therapy in dogs with spermatogenic dysfunction: a preliminary study.

Human chorionic gonadotropin (hCG) is a glycoprotein used in the treatment of spermatogenic dysfunction. However, previous studies performed in dogs show that repeated administration of large doses of hCG produces antibodies against hCG. In this study, we examined the efficacy of low-dose injections of hCG in four male dogs with spermatogenic dysfunction and low plasma testosterone (T) levels. We administered 100 IU hCG per animal, five times at 3-day intervals, and evaluated the changes in semen quality and plasma T levels. The total number of sperm in ejaculate, the percentage of progressively motile sperm and the plasma T levels had increased by 3-5 weeks after the first injection of hCG in three of the four dogs, but were unchanged in the fourth dog. These findings indicate that temporary improvement of the semen quality of dogs with spermatogenic dysfunction and low plasma T levels is possible after five low-dose injections of hCG.

Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot.

Nanofabricated quantum bits permit large-scale integration but usually suffer from short coherence times due to interactions with their solid-state environment. The outstanding challenge is to engineer the environment so that it minimally affects the qubit, but still allows qubit control and scalability. Here, we demonstrate a long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control. The spin is driven by resonant microwave electric fields in a transverse magnetic field gradient from a local micromagnet, and the spin state is read out in the single-shot mode. Electron spin resonance occurs at two closely spaced frequencies, which we attribute to two valley states. Thanks to the weak hyperfine coupling in silicon, a Ramsey decay timescale of 1 µs is observed, almost two orders of magnitude longer than the intrinsic timescales in GaAs quantum dots, whereas gate operation times are comparable to those reported in GaAs. The spin echo decay time is ~40 µs, both with one and four echo pulses, possibly limited by intervalley scattering. These advances strongly improve the prospects for quantum information processing based on quantum dots.

Spin-relaxation anisotropy in a GaAs quantum dot.

We report that the electron spin-relaxation time T_{1} in a GaAs quantum dot with a spin-1/2 ground state has a 180° periodicity in the orientation of the in-plane magnetic field. This periodicity has been predicted for circular dots as being due to the interplay of Rashba and Dresselhaus spin orbit contributions. Different from this prediction, we find that the extrema in the T_{1} do not occur when the magnetic field is along the [110] and [11[over ¯]0] crystallographic directions. This deviation is attributed to an elliptical dot confining potential. The T_{1} varies by more than 1 order of magnitude when rotating a 3 T field, reaching about 80 ms for the optimal angle. We infer from the data that in our device the signs of the Rashba and Dresselhaus constants are opposite.

Prolonged duration of fertility of dog ova.

The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2-3 days PO and viability of secondary oocytes for 48-60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 +/- 1.6 and 64.3 +/- 0.3 days, 4.0 +/- 1.4 and 66.3 +/- 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4-5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment.

Effect of catalase and superoxide dismutase on motility, viability and acrosomal integrity of frozen-thawed cat spermatozoa.

The aim of this study was to evaluate the effect of antioxidant catalase (CAT) and superoxide dismutase (SOD) in semen extender on motility, viability and acrosomal integrity of frozen-thawed cat spermatozoa. Semen was collected by using an artificial vagina from five domestic cats (two ejaculates/cat). Spermatozoa were diluted in egg yolk Ttris-fructose citrate solution (EYT-FC) without glycerol and cooled at 4 degrees C for 1 h, then diluted further with EYT-FC with glycerol (7% final concentration) and 400 IU/ml of CAT (treatment 1) or SOD (treatment 2) or without antioxidants (control). Before freezing using a styrofoam box, diluted spermatozoa filled in 0.25-ml straws were equilibrated for 1 h at 4 degrees C. After thawing, spermatozoa were assessed for motility, viability and acrosomal integrity. Cryopreservation significantly impaired sperm motility, viability and acrosomal integrity (p < 0.05). However, motility, viability and acrosomal integrity of frozen-thawed cat spermatozoa in the EYT-FC with CAT, SOD and without the antioxidants were not significantly different. The average percentages of spermatozoa motility after thawing compared between control, treatment 1 and treatment 2 group were 43.5 +/- 3.2, 42 +/- 4.1 and 38 +/- 4.5; for viability: 44.8 +/- 3.5, 50.6 +/- 5.7 and 47.1 +/- 4.1 and for acrosomal integrity: 45 +/- 3.5, 44.9 +/- 3.4 and 44.4 +/- 3.3, respectively. In conclusion, adding CAT and SOD to EYT-FC did not improve motility, viability and acrosomal integrity in cryopreserved cat spermatozoa.

The regular arrangement of collecting venules pattern evaluated by standard endoscope and the absence of antrum nodularity are highly indicative of Helicobacter pylori uninfected gastric mucosa.

AIM: To evaluate the accuracy of antrum nodularity and the regular arrangement of collecting venules for diagnosing Helicobacter pylori gastritis. METHODS: Ninety-nine consecutive children and adolescents (1.07 years-17.69 years, mean+/-S.D.=9.71+/-3.80 F:M 54:45) undergoing upper digestive endoscopy were assessed for the presence of antrum nodularity and regular arrangement of collecting venules pattern to determine the status of H. pylori infection. Antrum nodularity was observed by a tangential view of the greater curvature of the gastric antrum. Regular arrangement of collecting venules was visualized as being the regular pattern of red points evaluated with a standard endoscope. Two biopsies from the antrum were collected for histology and rapid urease test. The accuracy of diagnosis based on antrum nodularity and regular arrangement of collecting venules was evaluated considering the sensitivity, specificity and likelihood ratio. RESULTS: H. pylori was detected in 32/99 patients (32.3%). Antrum nodularity provided 59.4% sensitivity (95% confidence interval 50.7-68.1), 98.5% specificity (95% confidence interval: 97-100), likelihood ratio+ 39.78, and likelihood ratio- 0.41. A regular arrangement of collecting venules pattern provided 96.9% sensitivity (95% confidence interval: 93.8-100), 88.1% specificity (95% confidence interval: 84.1-92), likelihood ratio+ 8.11, and likelihood ratio- 0.04. CONCLUSION: Antrum nodularity is a specific finding, although its sensitivity is low. A regular arrangement of collecting venules pattern and the absence of antrum nodularity are highly indicative of normal gastric mucosa that is negative for Helicobacter pylori.

Carditis is related to Helicobacter pylori infection in dyspeptic children and adolescents.

BACKGROUND: Etiology of gastric cardia inflammation is still controversial. AIMS: To evaluate the association between carditis and Helicobacter pylori infection and the correlation among inflammatory changes observed in biopsies taken from cardia, corpus, and antrum in a well-defined group of patients. PATIENTS: The mean age of 45 dyspeptic patients was 10.4 years (range 5.1-17.0 years); gender F/M rate: 1.6/1. METHODS: A total of 450 specimens from esophagus (2), cardia (2), corpus (3), and antrum (4) were collected for biopsy. The presence of H. pylori was assessed by histology and a rapid urease test. The types of glandular epithelium of cardia found in specimens were identified and both inflammatory changes and H. pylori density were graded. RESULTS: Carditis was present in specimens of 30/45 (66.7%) of the patients. Presence of H. pylori in specimens was detected in the antrum (26/45; 57.8%), in the corpus (19/45; 42.2%), and in the cardia (14/45; 31.1%). There was a strong association between carditis and presence of H. pylori infection (OR=27.08) by multivariate analysis. The scores for inflammation and activity in the cardia, corpus and antrum have shown a relationship except for both cardia and antrum H. pylori density and corpus and cardia activity. The intensity of gastritis and degree of colonization with H. pylori were significantly higher in the antrum than in both the corpus and the cardia. Pangastritis was highly associated to H. pylori infection in 22/25 (88%) of the patients. CONCLUSIONS: 1. Carditis is associated to H. pylori infection in children with symptoms of dyspepsia; 2. The degrees of gastritis found at the cardia were correlated to those at the antrum and body except for both cardia and antrum H. pylori density and corpus and cardia activity.

Restitution of ischemic injuries in penumbra of cerebral cortex after temporary ischemia.

We investigated, at both light and ultrastructural levels, the fate of swollen astrocytes and remodeling of neurites connected to disseminated, dying neurons in the ischemic neocortical penumbra. Specimens from left cerebral cortex were cut coronally at the infundibulum and observed by light and electron microscopy. We measured synapses and spines, and the thickness of neuritic trunks in the neuropil on electron microscopy photos. We also determined percent volume of axon terminals and spines by Weibel's point-counting method. Astrocytic swelling gradually subsided from day 4 after the ischemic insult, with increases in cytoplasmic glial fibrils and GFAP-positive astrocytes. Disseminated dying electron-dense neurons were fragmented by invading astrocytic cell processes and accumulated as granular pieces. The number of synapses and spines and total percent volume of axon terminals and spines decreased with an increasing sparsity of synaptic vesicles until day 4. One to 12 weeks after the ischemic insult, these values increased to or exceeded control values, and sprouting and increased synaptic vesicles were seen. Axons that had been attached to the dying neurons appeared to have shifted their connections to the spines and the neurites of the surviving neurons, increasing their thickness. Astrocytic restitution and neuronal remodeling processes started at 4 days continuing until 12 weeks after ischemic insult.

Pituitary hormone responses to luteal regression after administration of prostaglandin F2alpha-analogue.

As an experiment to elucidate the canine luteal function maintenance system, a PGF2alpha-analogue, fenprostalene (PGF-F), was administered 24 and 54 days after ovulation to induce luteal regression, and the responses of luteinizing hormone (LH) and prolactin (PRL), which are considered to support the canine corpus luteum, were investigated. The plasma progesterone (P(4)) level was rapidly decreased, by which the plasma PRL level was increased, but no change was observed in the plasma LH level. The decrease in the plasma P(4) level after PGF-F administration may have induced positive feedback to the superior system, and stimulated secretion of the pituitary hormones. These findings suggested that the canine corpus luteum is maintained by PRL, not by LH.

Temporal profile of experimental ischemic edema after threshold amount of insult to induce infarction--ultrastructure, gravimetry and Evans' blue extravasation.

When a threshold amount of temporary ischemic insult to induce focal infarction was given to the unilateral cerebral hemisphere of gerbils, a small focal infarct surrounded by a wide penumbra developed in the rostral portion of the cerebral cortex. During the first 5 hours following recirculation, whole astrocytic cell bodies and processes in the ischemic hemisphere were swollen, with an increase in the number of glycogen granules and in number and size of mitochondria. This swelling was an active reaction of astrocytes for neuronal protection, scavenging potassium, glutamate, and other neuronal metabolic products, and for generating fuels for neurons (cyto-reactive edema). This reactive astrocytic swelling continued in the penumbra, but some dead neurons were found disseminated among the surviving neurons. Whereas, at 12 approximately 48 hours, focal infarction developed in which all cell membranes lost their Gibbs-Donnan's equilibrium due to energetic failure of their membranous Na+/K+ ATPase. This is the cytotoxic edema (cyto-necrotic edema). In the infarct focus, when pericapillary astrocytic end-feet were damaged, the capillary BBB was broken; and thus vasogenic edema was superimposed on the cytotoxic edema.

Changes in activities of enzymes related to energy metabolism in peripheral leukocytes of diabetic dogs with glycemic control by intensive insulin treatment.

Changes in plasma glucose, immunoreactive insulin (IRI), and free fatty acids (FFA) concentrations and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in type 1 diabetic dogs induced by streptozotocin administration before and after intensive insulin treatments. Before the insulin treatment, the plasma glucose concentrations were over 16.7 mmol/L and the activities of enzymes remarkably decreased in leukocytes of the diabetic dogs. In particular, malate dehydrogenase (MDH) activities decreased significantly. After glycemic control was achieved by insulin treatment, the plasma glucose concentrations were maintained between 6.8 and 7.7 mmol/L and the activities of enzymes restored to those in the control dogs. The changes in ML ratio (cytosolic MDH/lactate dehydrogenase specific activity ratio) reflected faithfully to metabolic conditions of animals and were considered to be a useful parameter to evaluate glycemic control and the effect of injected insulin in the diabetic dogs.

Changes in activities of enzymes related to energy metabolism in testicular tissues of dogs with seminoma.

Changes in the activities of enzymes related to energy metabolism in the testicular tissues of dogs with seminoma were investigated. The testis was removed surgically from animals anaesthetized with halothane. Cytosolic and mitochondrial fractions were isolated and the total RNA was extracted from testicular homogenates. The activities of enzymes related to energy metabolism were measured and the mRNA of cytosolic malate dehydrogenase (MDH) was investigated by the reverse transcriptase-polymerase chain reaction (RT-PCR). The activities of the glycolytic enzymes glucose-6-phosphate dehydrogenase (G6PD) for the pentose phosphate pathway and malate dehydrogenase (MDH) for the malate-aspartate shuttle, and the expression of the mRNA of cytosolic MDH were significantly increased in the testicular tissues of dogs with seminoma. These enzymatic activities may be useful indicators with which to evaluate changes in the metabolic conditions in testicular tissues of dogs with seminoma.

Effects of canine oviduct epithelial cells on movement and capacitation of homologous spermatozoa in vitro.

In this study, the interaction between canine sperms and oviduct epithelial cells (OECs) was examined in vitro. The oviducts of eight bitches in the follicular (F-) phase and six bitches in the luteal (L-) phase were removed under halothane inhalation anesthesia. The entire oviduct was opened longitudinally, and the oviductal epithelium of bitches in the F- and L-phases was scraped with a scalpel into tissue culture medium (Eagle's MEM) containing 10% estrous bitch serum and 10% diestrous bitch serum, respectively. The OEC collected were preincubated for 24h and then coincubated with ejaculated canine sperms at 38 degrees C under an atmosphere of 5% CO2 in air. The percentages of sperms exhibiting active tail movement (% TM), hyperactivated sperms (% HA), and acrosome-reacted sperms (% AR) were investigated until 72 h after the start of coincubation. The percentage of sperms labeled with fluoresceinated Ca indicator (% Ca) was evaluated to assess the influx of Ca into sperms cytoplasm during capacitation. Canine sperms attached to both ciliated OEC and non-ciliated OEC. All of the mean % TM of the OEC-binding sperms in the F-OEC and L-OEC media after 24, 48, and 72 h of coincubation were significantly higher than the values of the freely swimming sperms (P< or =0.01). Conversely, the mean % AR and % Ca of the OEC-binding sperms were significantly lower (P<0.01). All of the mean % HA and % AR of the freely swimming sperms in the F-OEC medium after 24, 48, and 72 h of coincubation were significantly higher than the values of the sperms in the L-OEC medium (P< or =0.01). These results indicate that attachment of canine sperms to the OEC prolongs their viability and motility arid inhibits Ca influx into the sperms and sperm capacitation. These phenomena may be responsible for maintaining the active movement and the fertile life of canine sperms in homologous oviducts.

Relationship between testicular transferrin and plasma estradiol-17beta concentrations of dogs with azoospermia and dogs with sertoli cell tumors.

Testicular Transferrin (Tf) and peripheral plasma estradiol-17beta (E2) concentrations were measured in 3 dogs with azoospermia (AZ dogs), 3 dogs with Sertoli cell tumors (SC dogs), and 5 normal male Beagles. The mean Tf concentrations in the testes of the AZ dogs and the affected testes of the SC dogs, and the plasma E2 concentrations in both these groups of dogs were significantly higher than the values in normal dogs (P<0.05, 0.01 and 0.01, respectively). Therefore, excessive E2 secretion by hyperfunctioning Sertoli cells is thought to have caused the azoospermia in the 3 dogs.

Transfer of canine embryos at various developmental stages recovered by hysterectomy or surgical uterine flushing.

In dogs, embryo transfer (ET) techniques such as induciton of excessive ovulation and synchronization of estrus have not progressed well. Therefore, using embryos at various developmental stages, ET was investigated in dogs from a beagle colony in which the ovulation days were close, as estimated by the progesterone level. Embryos were, recovered 8-11 days after ovulation (4-9 days after mating) by excising the oviducts and uteri (excision method) in 16 animals and by surgical flushing of the uteri at laparotomy (surgical method) in 3 animals. In 24 dogs with -4 to +2 days of difference in the timing of ovulation between donor and recipient dogs, 1-10 embryos at the 8-cell to blastocyst stages were transferred per animal. The mean embryo recovery rate by the excision method (97.1%) was significantly higher than that by the surgical method (42.5%) (p<0.01). Twelve (57.1%) of 21 animals with -1 to +2 days difference in ovulation day became pregnant after the transfer of 8-cell to blastocyst stage embryos. Although 3 dogs with -4 to -2 days of difference of ovulation day underwent ET of morula or compacted morula, none of these dogs became pregnant. The mean ratio of the number of newborns to the number of transferred embryos was only 51.9%. The mean duration of the period between ovulation and delivery in the pregnant recipients was 65.8 days, which tended to be longer than that in natural mating. These results demonstrate that pregnancy can be induced by ET at the 8-cell to blastocyst stage in dogs with -1 to +2 days difference in ovulation day.