G-U base-paired hpRNA confers potent inhibition of small RNA function in plants

MicroRNA (miRNA) target mimicry technologies, utilizing naturally occurring miRNA decoy molecules, represent a potent tool for analyzing miRNA function. In this study, we present a highly efficient small RNA (sRNA) target mimicry design based on G-U base-paired hairpin RNA (hpG:U), which allows for the simultaneous targeting of multiple sRNAs. The hpG:U constructs consistently generate high amounts of intact, polyadenylated stem-loop (SL) RNA outside the nuclei, in contrast to traditional hairpin RNA designs with canonical base pairing (hpWT), which were predominantly processed resulting in a loop. By incorporating a 460-bp G-U base-paired double-stranded stem and a 312-576 nt loop carrying multiple miRNA target mimicry sites (GUMIC), the hpG:U construct displayed effective repression of three Arabidopsis miRNAs, namely miR165/166, miR157, and miR160, both individually and in combination. Additionally, a GUMIC construct targeting a prominent cluster of siRNAs derived from cucumber mosaic virus (CMV) Y-satellite RNA (Y-Sat) effectively inhibited Y-Sat siRNA-directed silencing of the chlorophyll biosynthetic gene CHLI, thereby reducing the yellowing symptoms in infected Nicotiana plants. Therefore, the G-U base-paired hpRNA, characterized by differential processing compared to traditional hpRNA, acts as an efficient decoy for both miRNAs and siRNAs. This technology holds great potential for sRNA functional analysis and the management of sRNA-mediated diseases.

A prospective observational study of the effects of sugammadex on peri-operative oestrogen and progesterone levels in women who take hormonal contraception

Pharmacokinetic modelling suggests that sugammadex may interact with endogenous progesterone and reduce levels by 34% in patients taking hormonal contraception. Due to this potential interaction that may be equivalent to missing one dose of an oral contraceptive pill, both the manufacturer and professional anaesthesia organisations recommend counselling patients to use additional non-hormonal contraception after administration of sugammadex. We performed a prospective observational study examining the changes in serum oestrogen and progesterone concentrations in premenopausal adult women undergoing an operative procedure. Sixty participants who were on hormonal contraception received sugammadex. Two additional control groups were recruited, consisting of 30 participants who were not on hormonal contraception and did not receive sugammadex, and 32 who were not on hormonal contraception and did receive sugammadex. Three blood samples were taken: before sugammadex; 15 min post-sugammadex; and 240 min post-sugammadex or end of operating theatre time. Median oestrogen levels decreased from baseline by around 40% at 240 min in all three groups (p ≤ 0.001). Progesterone levels rose significantly at 15 min (p = 0.002) in patients on contraception then decreased non-significantly to 20% below baseline at 240 min. The decrease in oestrogen and the rise in progesterone could both act to minimise the risk of ovulation and thus protect contraception in this population. We found no evidence of a change in hormone levels that might threaten contraceptive efficacy in women on hormonal contraception receiving sugammadex.

Unilateral diaphragmatic paresis following supracostal post-percutaneous nephrolithotomy

Unilateral acquired diaphragmatic paresis is a known complication of thoracic surgeries. Direct mechanical injury to the phrenic nerve during surgery results in this complication. However its occurrence post-percutaneous nephrolithotomy (PCNL) has not been described. We report a 43-year-old man who underwent prone PCNL for endourological management of left complete staghorn calculus. Access via the 10^th left intercostal space, under fluoroscopy, was carried out to remove the calculus. Post-operative, the routine chest radiograph revealed left hemidiaphragmatic blunting. Computerized tomography of the chest confirmed left hemidiaphragmatic elevation, suggesting unilateral diaphragmatic paresis. He did not have any respiratory symptoms, was managed conservatively with chest physiotherapy and incentive spirometry and responded extremely well. The absence of reported cases of diaphragmatic paresis post PCNL lends to a dearth in knowledge regarding recognition and management. This case report aims to acquaint urologists with this rare complication associated with supracostal PCNL and provide a rational management plan.

Is it safe to perform elective orthopaedic surgery with high community rates of COVID-19? An observational cohort study

INTRODUCTION

During the first wave of the COVID-19 pandemic, University Hospitals Birmingham NHS Foundation trust was able to recommence elective orthopaedic surgery using private hospitals procured by the NHS as COVID-19 free 'green' sites. We report on the safety of elective orthopaedic surgery with high rates of community transmission.

METHODS

We conducted an observational cohort study on consecutive NHS patients attending three private hospitals between 4 May 2020 and 16 June 2020. Patients attended preoperative assessment, including coronavirus disease (COVID-19) symptom screening, were instructed to self-isolate for 14 days and had a negative COVID-19 swab within 72 hours of surgery. Patient age, American Society of Anesthesiologists (ASA) grade, body mass index, surgery performed, type of anaesthetic and length of stay were collected. Our primary outcome was a positive COVID-19 swab, secondary outcomes were COVID-19 symptoms, readmission, surgical complications and mortality.

RESULTS

Between 4 May 2020 and 16 June 2020, 191 patients were admitted to three private hospitals for elective surgery; 121 (67%) patients underwent general or regional anaesthetic, 179 patients were ASA grades 1 or 2 (94%) and 12 (6%) were ASA 3. In total, 187 (98%) patients were successfully contacted at 30 days postoperative and no COVID-19 symptoms, positive COVID-19 swabs or mortality or were recorded. One patient was readmitted following a pulmonary embolism and two patients were treated as outpatients for a deep vein thrombosis and a superficial infection.

CONCLUSION

With 'green pathways' elective orthopaedic surgery can safely be performed while rates of COVID-19 in the community are high.

The evolution of mammalian brain size

Relative brain size has long been considered a reflection of cognitive capacities and has played a fundamental role in developing core theories in the life sciences. Yet, the notion that relative brain size validly represents selection on brain size relies on the untested assumptions that brain-body allometry is restrained to a stable scaling relationship across species and that any deviation from this slope is due to selection on brain size. Using the largest fossil and extant dataset yet assembled, we find that shifts in allometric slope underpin major transitions in mammalian evolution and are often primarily characterized by marked changes in body size. Our results reveal that the largest-brained mammals achieved large relative brain sizes by highly divergent paths. These findings prompt a reevaluation of the traditional paradigm of relative brain size and open new opportunities to improve our understanding of the genetic and developmental mechanisms that influence brain size.

DEMETER plays a role in DNA demethylation and disease response in somatic tissues of Arabidopsis

DNA demethylases function in conjunction with DNA methyltransferases to modulate genomic DNA methylation levels in plants. The Arabidopsis genome contains four DNA demethylase genes, DEMETER (DME), REPRESSOR OF SILENCING 1 (ROS1) also known as DEMETER-LIKE 1 (DML1), DML2, and DML3. While ROS1, DML2, and DML3 were shown to function in disease response in somatic tissues, DME has been thought to function only in reproductive tissues to maintain the maternal-specific expression pattern of a subset of imprinted genes. Here we used promoter:β-glucuronidase (GUS) fusion constructs to show that DME is constitutively expressed throughout the plant, and that ROS1, DML2, and DML3 have tissue-specific expression patterns. Loss-of-function mutations in DME cause seed abortion and therefore viable DME mutants are not available for gene function analysis. We knocked down DME expression in a triple ros1 dml2 dml3 (rdd) mutant background using green tissue-specific expression of a hairpin RNA transgene (RNAi), generating a viable 'quadruple' demethylase mutant line. We show that this rdd DME RNAi line has enhanced disease susceptibility to Fusarium oxysporum infection compared to the rdd triple mutant. Furthermore, several defence-related genes, previously shown to be repressed in rdd, were further repressed in the rdd DME RNAi plants. DNA methylation analysis of two of these genes revealed increased differential promoter DNA methylation in rdd DME RNAi plants compared to WT, beyond the difference observed in the parental rdd plants. These results indicate that DME contributes to DNA demethylase activity and disease response in somatic tissues.

The use of triclosan-coated sutures to prevent surgical site infections: a systematic review and meta-analysis of the literature

INTRODUCTION AND OBJECTIVES

Surgical site infections (SSIs) represent a common and serious complication of all surgical interventions. Microorganisms are able to colonise sutures that are implanted in the skin, which is a causative factor of SSIs. Triclosan-coated sutures are antibacterial sutures aimed at reducing SSIs. Our objective is to update the existing literature by systematically reviewing available evidence to assess the effectiveness of triclosan-coated sutures in the prevention of SSIs.

METHODS

A systematic review of EMBASE, MEDLINE, AMED (Allied and complementary medicine database) and CENTRAL was performed to identify full text randomised controlled trials (RCTs) on 31 May 2019.

INTERVENTION

Triclosan-coated sutures versus non-triclosan-coated sutures.

PRIMARY OUTCOME

Our primary outcome was the development of SSIs at 30 days postoperatively. A meta-analysis was performed using a fixed-effects model.

RESULTS

Twenty-five RCTs were included involving 11 957 participants. Triclosan-coated sutures were used in 6008 participants and non triclosan-coated sutures were used in 5949. Triclosan-coated sutures significantly reduced the risk of SSIs at 30 days (relative risk 0.73, 95% CI 0.65 to 0.82). Further sensitivity analysis demonstrated that triclosan-coated sutures significantly reduced the risk of SSIs in both clean and contaminated surgery.

CONCLUSION

Triclosan-coated sutures have been shown to significantly reduced the risk of SSIs when compared with standard sutures. This is in agreement with previous work in this area. This study represented the largest review to date in this area. This moderate quality evidence recommends the use of triclosan-coated sutures in order to reduce the risk of SSIs particularly in clean and contaminated surgical procedures.

PROSPERO REGISTRATION NUMBER

CRD42014014856.

Full-Length Hairpin RNA Accumulates at High Levels in Yeast but Not in Bacteria and Plants

Hairpin-structured (hp) RNA has been widely used to induce RNA interference (RNAi) in plants and animals, and an in vivo expression system for hpRNA is important for large-scale RNAi applications. Bacterial expression systems have so far been developed for in vivo expression of hpRNA or double-stranded (ds) RNA, but the structure of the resulting RNAi molecules has remained unclear. Here we report that long hpRNAs expressed in the bacteria Escherichia coli and Sinorhizobium meliloti were largely processed into shorter dsRNA fragments with no or few full-length molecules being present. A loss-of-function mutation in the dsRNA-processing enzyme RNase III, in the widely used E. coli HT115 strain, did not prevent the processing of hpRNA. Consistent with previous observations in plants, the loop sequence of long hpRNA expressed in Agrobacterium-infiltrated Nicotiana benthamiana leaves was excised, leaving no detectable levels of full-length hpRNA molecule. In contrast to bacteria and plants, long hpRNAs expressed in the budding yeast Saccharomyces cerevisiae accumulated as intact, full-length molecules. RNA extracted from hpRNA-expressing yeast cells was shown to be capable of inducing RNAi against a β-glucuronidase (GUS) reporter gene in tobacco leaves when applied topically on leaf surfaces. Our results indicate that yeast can potentially be used to express full-length hpRNA molecules for RNAi and perhaps other structured RNAs that are important in biological applications.

Therapeutic doses of neostigmine, depolarising neuromuscular blockade and muscle weakness in awake volunteers: a double-blind, placebo-controlled, randomised volunteer study

Neostigmine reverses non-depolarising neuromuscular blockade, but may cause muscle weakness when administered after full recovery of neuromuscular function. We hypothesised that neostigmine in therapeutic doses impairs muscle strength and respiratory function in awake healthy volunteers. Twenty-one volunteers were randomised to receive two doses of either intravenous (i.v.) neostigmine 2.5 mg with glycopyrrolate 450 μg (neostigmine group, n = 14) or normal saline 0.9% (placebo group, n = 7). The first dose was administered immediately after obtaining baseline measurements, and the second dose was administered 15 min later. All 14 volunteers in the neostigmine group received the first dose, mean (SD) 35 (5.8) μg.kg^-1 , but only nine of these volunteers agreed to receive the second dose, 34 (3.5) ?g.kg^-1 . The primary outcome was hand grip strength. Secondary outcomes were train-of-four ratio, single twitch height, forced expiratory volume in 1 s, forced vital capacity, forced expiratory volume in 1 s/forced vital capacity ratio, oxygen saturation, heart rate and mean arterial pressure. The first dose of intravenous neostigmine with glycopyrrolate resulted in reduced grip strength compared with placebo, -20 (20) % vs. +4.3 (9.9) %, p = 0.0016; depolarising neuromuscular blockade with decreased single twitch height, -14 (11) % vs. -3.8 (5.6) %, p = 0.0077; a restrictive spirometry pattern with decreased predicted forced expiratory volume in 1 s, -15 (12) % vs. -0.47 (3.4) %, p = 0.0011; and predicted forced vital capacity, -20 (12) % vs. -0.59 (3.2) %, p < 0.0001 at 5 min after administration. The second dose of neostigmine with glycopyrrolate further decreased grip strength mean (SD) -41 (23) % vs. +1.0 (15) %, p = 0.0004; single twitch height -25 (15) % vs. -2.5 (6.6) %, p = 0.0030; predicted forced expiratory volume in 1 s -23 (24) % vs. -0.7 (4.4) %, p = 0.0063; and predicted forced vital capacity, -27.1 (22.0) % vs. -0.66 (3.9) %, p = 0.0010. Train-of-four ratio remained unchanged (p = 0.22). In healthy volunteers, therapeutic doses of neostigmine induced significant and dose-dependent muscle weakness, demonstrated by a decrease in maximum voluntary hand grip strength and a restrictive spirometry pattern secondary to depolarising neuromuscular blockade.

Root-Specific Expression of a Jacalin Lectin Family Protein Gene Requires a Transposable Element Sequence in the Promoter

Transposable elements (TEs) are widespread in the plant genome and can impact on the expression of neighbouring genes. Our previous studies have identified a number of DNA demethylase-regulated defence-related genes that contain TE sequences in the promoter and show tissue-specific expression in Arabidopsis. In this study we investigated the role of the promoter TE insertions in the root-specific expression of a DNA demethylase-regulated gene, AT5G38550, encoding a Jacalin lectin family protein. Using a promoter:GUS fusion reporter gene approach, we first demonstrated that the full-length promoter fragment, carrying four TE sequences, contained the essential regulatory information required for root-specific expression and DNA demethylase regulation in Arabidopsis. By successive deletion of the four TE sequences, we showed that one of the four TE insertions, a 201-bp TE fragment of the hAT DNA transposon family, was required for root-specific expression: Deletion of this TE, but not the first two TE sequences, converted the root-specific expression pattern to a constitutive expression pattern in Arabidopsis plants. Our study provides an example indicating an important role of TE insertions in tissue-specific expression of plant defence-related genes.

Survey of occupational fatigue in anaesthetists in Australia and New Zealand

Occupational fatigue in anaesthetists is recognised as a patient safety risk. Better understanding of the issues surrounding their fatigue is needed. This study aimed to ascertain the sources and effects of occupational fatigue amongst anaesthetists in Australia and New Zealand. An anonymous online survey was sent to 979 anaesthetists. The response rate was 38.0%. Most participants reported regularly working over 40 hours per week; men reported five more hours per week than women. Stated contributors to fatigue included long work hours, mental strain at work, and personal and family demands. Fatigue-related behaviour was reported more by men (OR [odds ratio]=2.6) and less by respondents reporting eight or more hours of sleep before work (OR=0.6). Reporting at least one instance of less than five hours off between shifts was predictive of falling asleep while administering an anaesthetic (OR=1.6). More data are required to support practices and policies that promote more time off between work periods and increased time for sleep to reduce risk of fatigue.

A pilot randomized trial of meniscal allograft transplantation versus personalized physiotherapy for patients with a symptomatic meniscal deficient knee compartment

AIMS

Meniscal allograft transplantation is undertaken to improve pain and function in patients with a symptomatic meniscal deficient knee compartment. While case series have shown improvements in patient reported outcome measures (PROMs), its efficacy has not been rigorously evaluated. This study aimed to compare PROMs in patients having meniscal transplantation with those having personalized physiotherapy at 12 months.

PATIENTS AND METHODS

A single-centre assessor-blinded, comprehensive cohort study, incorporating a pilot randomized controlled trial (RCT) was performed on patients with a symptomatic compartment of the knee in which a (sub)total meniscectomy had previously been performed. They were randomized to be treated either with a meniscal allograft transplantation or personalized physiotherapy, and stratified for malalignment of the limb. They entered the preference groups if they were not willing to be randomized. The Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score and Lysholm score and complications were collected at baseline and at four, eight and 12 months following the interventions.

RESULTS

A total of 36 patients entered the study; 21 were randomized and 15 chose their treatments. Their mean age was 28 years (range 17 to 46). The outcomes were similar in the randomized and preference groups, allowing pooling of data. At 12 months, the KOOS₄ composite score (mean difference 12, p = 0.03) and KOOS subscales of pain (mean difference 15, p = 0.02) and activities of daily living (mean difference 18, p = 0.005) were significantly superior in the meniscal transplantation group. Other PROMs also favoured this group without reaching statistical significance. There were five complications in the meniscal transplantation and one in the physiotherapy groups.

CONCLUSION

This is the first study to compare meniscal allograft transplantation to non-operative treatment. The results provide the best quality evidence to date of the symptomatic benefits of meniscal allograft transplantation in the short term, but a multicentre RCT is required to investigate this question further. Cite this article: Bone Joint J 2018;100-B:56-63.

Postoperative troponin measurement as a screening tool for adverse cardiac events in adult patients undergoing moderate or major non-cardiac surgery

Elevated troponin levels within three days of surgery are strongly linked to major adverse cardiac events (MACE). However, the value of screening with troponin measurements is controversial. The extent to which this is done in routine practice is uncertain. We examined the medical records of all patients ≥45 years of age undergoing moderate or major non-cardiac surgery in our tertiary referral hospital over a six-month period. We determined how many patients had a troponin (TnT) measurement recorded in the first three days postoperatively, how many of these were abnormal, and the occurrence of MACE within 30 days. Two thousand and two hundred patients underwent 2,577 operations that met the study criteria. A postoperative TnT was measured after 4.5% of operations. Thirty-eight percent of patients with a recorded TnT measurement, and 44% of those with an abnormal measurement, experienced a MACE within 30 days. The sensitivity of an abnormal TnT to detect MACE was 86%. The specificity was low at 32% with a false positive rate of 56%. Patients with an abnormal TnT result had an increased risk of MACE (23%). The 'number needed to measure' to detect one patient with MACE was 4.4. In our institution, postoperative TnT levels were rarely measured and were used as a diagnostic rather than as a screening tool. The high false positive rate for MACE prediction limits its potential value as a screening tool. The test could be considered useful if it leads to further investigation, and may be best considered as one component of a multivariate approach to cardiac risk evaluation and diagnosis.

Use of the Montreal Cognitive Assessment test to investigate the prevalence of mild cognitive impairment in the elderly elective surgical population

Postoperative cognitive disorders are common in elderly patients. Pre-existing cognitive impairment including mild cognitive impairment may be an important risk factor for developing postoperative cognitive dysfunction and may not be detected in a standard preoperative interview, yet is not routinely sought. Our primary aim was to estimate the prevalence of mild cognitive impairment among elderly patients presenting to our hospital for elective surgery using a simple established screening tool: the Montreal Cognitive Assessment test. Secondarily, we wished to determine the proportion of patients with mild cognitive impairment who presented with this information available, the effect of increasing age on the prevalence of mild cognitive impairment and whether the timing and location of testing influenced results. We used the Montreal Cognitive Assessment test to screen preoperative patients aged 65 years and over. Our results suggested a potential prevalence of mild cognitive impairment of 56%, with prevalence increasing with age. No patients in the sample had a recorded diagnosis of mild cognitive impairment. Testing in either the preadmission clinic or on admission on the day of surgery yielded similar results. We found the Montreal Cognitive Assessment test to be a simple screening tool that was easily administered during the pre-admission visit.

RNA Silencing in Plants: Mechanisms, Technologies and Applications in Horticultural Crops

Understanding the fundamental nature of a molecular process or a biological pathway is often a catalyst for the development of new technologies in biology. Indeed, studies from late 1990s to early 2000s have uncovered multiple overlapping but functionally distinct RNA silencing pathways in plants, including the posttranscriptional microRNA and small interfering RNA pathways and the transcriptional RNA-directed DNA methylation pathway. These findings have in turn been exploited for developing artificial RNA silencing technologies such as hairpin RNA, artificial microRNA, intrinsic direct repeat, 3' UTR inverted repeat, artificial trans-acting siRNA, and virus-induced gene silencing technologies. Some of these RNA silencing technologies, such as the hairpin RNA technology, have already been widely used for genetic improvement of crop plants in agriculture. For horticultural plants, RNA silencing technologies have been used to increase disease and pest resistance, alter plant architecture and flowering time, improve commercial traits of fruits and flowers, enhance nutritional values, remove toxic compounds and allergens, and develop high-value industrial products. In this article we aim to provide an overview of the RNA silencing pathways in plants, summarize the existing RNA silencing technologies, and review the current progress in applying these technologies for the improvement of agricultural crops particularly horticultural crops.

Patient-delivered partner medication in the UK: an unlawful but popular choice

Current methods of contact tracing are only partially effective. Patient-delivered partner medication (PDPM), in which patients are dispensed antibiotics for their sexual partner(s), has been shown to reduce persistent and recurrent infections. We performed a questionnaire to canvass opinions of UK staff and patients about PDPM. The response rate was 72% (88/122) for staff and 90% (473/525) for patients. The majority of staff (81%) thought that PDPM would be acceptable to patients, and should be combined with written information and a recommendation to attend a clinic. Patients were mostly (59%) in favour of PDPM, 87% thought it would make it easier to abstain from sex during treatment, and 94% indicated that after being given antibiotics by a partner, they would attend a clinic for tests. Concerns expressed by staff and patients included drug allergies, potential lack of information provided to partners, management of complicated infection, pregnancy and medicolegal implications.

Relationship between parity and brachial plexus injuries

OBJECTIVE

Few characteristics have been identified as risk factors for brachial plexus injuries. We sought to investigate a potential relationship with multiparity based on clinical observation at our institution.

STUDY DESIGN

In this retrospective case series, we analyzed all brachial plexus injuries recognized at or after delivery between October 2003 and March 2013 (n=78) at a single academic medical institution. Patient, infant, labor and delivery characteristics were compared for women with and without prior vaginal deliveries.

RESULT

Of the 78 injuries, 71 (91%) occurred after a vaginal delivery and 7 (9%) after a cesarean delivery. Of the 71 injuries after a vaginal delivery, 58% occurred in women with a prior vaginal delivery (n=41, 5.7 per 10 000 live births) compared with 42% without a prior vaginal delivery (n=30, 4.0 per 10 000 live births). Multiparous patients had shorter labor courses and fewer labor interventions than nulliparous patients. Providers clinically underestimated the birth weights to a greater extent in multiparas than in nulliparas (median underestimation 590 vs 139 g, P=0.0016). The median birth weight was 4060 g in the multiparous group, which was significantly larger than affected infants born to the nulliparous group (3591 g, P=0.006). The affected infants of the multiparous group were, as expected, significantly larger than their previously born siblings (median 567 g larger, P<0.001).

CONCLUSION

Brachial plexus injuries occurred as frequently in multiparous patients as in nulliparous patients. In general, multiparous patients are more likely to have larger infants; however, providers significantly underestimate the birth weight of their infants. The findings of this study should deter providers from assuming that a prior vaginal delivery is protective against brachial plexus injuries.

Satellite RNA pathogens of plants: impacts and origins-an RNA silencing perspective

Viral satellite RNAs (satRNAs) are among the smallest RNA pathogens in plants. They have little or no protein-coding capacity but can have a major impact on the host plants through trilateral interactions with helper viruses and host plants. Studies around the 1980s revealed much of what we know about satRNAs: they can affect helper virus accumulation, modulate helper virus-induced disease symptoms, and induce their own symptoms with the assistance of helper viruses which depend on specific nucleotide sequences of their genome and host species. The molecular basis of these satRNA-caused impacts and the origin of satRNAs have yet to be fully understood and revealed, but recent understanding of the antiviral RNA silencing pathways and advancement in RNA and DNA sequencing technologies have provided new avenues and opportunities to examine these unanswered questions. These RNA silencing-based studies have revealed the existence of cross silencing between some satRNAs and helper viruses, the downregulation of helper virus-encoded suppressor (VSR) of RNA silencing or inhibition/enhancement of VSR activity by satRNAs, the silencing of host-encoded genes by satRNA-derived small interfering RNA (siRNAs), and the presence of satRNA-like small RNAs in uninfected host plants. These findings have provided alternative RNA silencing-based models to explain the pathogenicity and origin of satRNAs. WIREs RNA 2016, 7:5-16. doi: 10.1002/wrna.1311 For further resources related to this article, please visit the WIREs website.

Observation of the B(s)(0)→η'η' Decay

The first observation of the B(s)(0)→η'η' decay is reported. The study is based on a sample of proton-proton collisions corresponding to 3.0  fb(-1) of integrated luminosity collected with the LHCb detector. The significance of the signal is 6.4 standard deviations. The branching fraction is measured to be [3.31±0.64(stat)±0.28(syst)±0.12(norm)]×10(-5), where the third uncertainty comes from the B(±)→η'K(±) branching fraction that is used as a normalization. In addition, the charge asymmetries of B(±)→η'K(±) and B(±)→ϕK(±), which are control channels, are measured to be (-0.2±1.3)% and (+1.7±1.3)%, respectively. All results are consistent with theoretical expectations.

Measurement of CP Violation in B0→J/ψK{S}^{0} Decays

Measurements are presented of the CP violation observables S and C in the decays of B(0) and Bover ¯]0 mesons to the J/ψK(S)(0) final state. The data sample corresponds to an integrated luminosity of 3.0  fb(-1) collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, and contains a total of 41 560 selected B^{0} and B[over ¯]^{0} decays. The analysis of the time evolution of these decays yields S=0.731±0.035(stat)±0.020(syst) and C=-0.038±0.032(stat)±0.005(syst). In the standard model, S equals sin(2β) to a good level of precision. The values are consistent with the current world averages and with the standard model expectations.

Meniscal Transplantation and its Effect on Osteoarthritis Risk: an abridged protocol for the MeTEOR study: a comprehensive cohort study incorporating a pilot randomised controlled trial

OBJECTIVES

Subtotal or total meniscectomy in the medial or lateral compartment of the knee results in a high risk of future osteoarthritis. Meniscal allograft transplantation has been performed for over thirty years with the scientifically plausible hypothesis that it functions in a similar way to a native meniscus. It is thought that a meniscal allograft transplant has a chondroprotective effect, reducing symptoms and the long-term risk of osteoarthritis. However, this hypothesis has never been tested in a high-quality study on human participants. This study aims to address this shortfall by performing a pilot randomised controlled trial within the context of a comprehensive cohort study design.

METHODS

Patients will be randomised to receive either meniscal transplant or a non-operative, personalised knee therapy program. MRIs will be performed every four months for one year. The primary endpoint is the mean change in cartilage volume in the weight-bearing area of the knee at one year post intervention. Secondary outcome measures include the mean change in cartilage thickness, T2 maps, patient-reported outcome measures, health economics assessment and complications.

RESULTS

This study is expected to report its findings in 2016. Cite this article: Bone Joint Res 2015;4:93-8.

Satellite RNAs interfere with the function of viral RNA silencing suppressors

Viral satellite RNAs (satRNAs) are small subviral RNAs and depend on the helper virus for replication and spread. satRNAs can attenuate helper virus-induced symptoms, the mechanism of which remains unclear. Here, we show that two virus-encoded suppressors of RNA silencing (VSRs), Cucumber mosaic virus (CMV) 2b and Tombusvirus P19, suppress hairpin RNA (hpRNA)-induced silencing of a β-glucuronidase (GUS) gene in Nicotiana benthamiana. This suppression can be overcome by CMV Y-satellite RNA (Y-Sat) via the Y-Sat-derived small interfering RNAs (siRNAs), which bind to the VSRs and displace the bound hpGUS-derived siRNAs. We also show that microRNA target gene expression in N. tabacum was elevated by CMV infection, presumably due to function of the 2b VSR, but this upregulation of microRNA target genes was reversed in the presence of Y-Sat. These results suggest that satRNA infection minimizes the effect of VSRs on host siRNA and microRNA-directed silencing. Our results suggest that the high abundance of satRNA-derived siRNAs contributes to symptom attenuation by binding helper virus-encoded VSRs, minimizing the capacity of the VSRs to bind host siRNA and miRNA and interfere with their function.

Measuring the clinical learning environment in anaesthesia

The learning environment describes the way that trainees perceive the culture of their workplace. We audited the learning environment for trainees throughout Australia and New Zealand in the early stages of curriculum reform. A questionnaire was developed and sent electronically to a large random sample of Australian and New Zealand College of Anaesthetists trainees, with a 26% final response rate. This new instrument demonstrated good psychometric properties, with Cronbach's α ranging from 0.81 to 0.91 for each domain. The median score was equivalent to 78%, with the majority of trainees giving scores in the medium range. Introductory respondents scored their learning environment more highly than all other levels of respondents (P=0.001 for almost all comparisons). We present a simple questionnaire instrument that can be used to determine characteristics of the anaesthesia learning environment. The instrument can be used to help assess curricular change over time, alignment of the formal and informal curricula and strengths and weaknesses of individual departments.

Measurement of Bc+ Production in Proton-Proton Collisions at √[s]=8 TeV

Production of Bc+ mesons in proton-proton collisions at a center-of-mass energy of 8 TeV is studied with data corresponding to an integrated luminosity of 2.0  fb-1 recorded by the LHCb experiment. The ratio of production cross sections times branching fractions between the Bc+→J/ψπ+ and B+→J/ψK+ decays is measured as a function of transverse momentum and rapidity in the regions 0<pT<20  GeV/c and 2.0<y<4.5. The ratio in this kinematic range is measured to be (0.683±0.018±0.009)%, where the first uncertainty is statistical and the second systematic.

Anaesthesia priorities for Australian and New Zealand medical school curricula: a Delphi consensus of academic anaesthetists

The role of anaesthetists has expanded and evolved to include critical care, perioperative and pain medicine and general clinical skills, as well as operating theatre-based clinical anaesthesia. Across Australia and New Zealand, these topics are taught to varying degrees, however no uniform curriculum or standardisation exists between universities. In this study, we used a Delphi technique to develop consensus-based priorities to guide medical educators when reviewing and implementing student anaesthesia curricula. A range of appropriate content has been defined, as well as details relating to duration, timing, teaching environment, faculty, feedback and assessment methods. Future enquiry to assess the efficacy of future and current teaching practices is needed to facilitate continued improvement.

Observation of two new Ξ(b)(-) baryon resonances

Two structures are observed close to the kinematic threshold in the Ξ(b)(0)π(-) mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0  fb(-1), recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity J(P)=(1/2)(+) and J(P)=(3/2)(+) states, denoted Ξ(b)('-) and Ξ(b)(*-). Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ(b)('-))-m(Ξ(b)(0))-m(π(-))=3.653±0.018±0.006  MeV/c(2), m(Ξ(b)(*-))-m(Ξ(b)(0))-m(π(-))=23.96±0.12±0.06  MeV/c(2), Γ(Ξ(b)(*-))=1.65±0.31±0.10  MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ(b)('-))<0.08  MeV at 95% confidence level. Relative production rates of these states are also reported.

Precision measurement of CP violation in B(S)(0)→J/ΨK+K- decays

The time-dependent CP asymmetry in B(s)(0)→J/ψK+K- decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0  fb-1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. In a sample of 96,000 B(s)(0)→J/ψK+K- decays, the CP-violating phase ϕs is measured, as well as the decay widths ΓL and ΓH of the light and heavy mass eigenstates of the B(s)(0)-B[over ¯]s0 system. The values obtained are ϕs=-0.058±0.049±0.006  rad, Γs≡(ΓL+ΓH)/2=0.6603±0.0027±0.0015  ps-1, and ΔΓs≡ΓL-ΓH=0.0805±0.0091±0.0032  ps-1, where the first uncertainty is statistical and the second, systematic. These are the most precise single measurements of those quantities to date. A combined analysis with Bs0→J/ψπ+π- decays gives ϕs=-0.010±0.039  rad. All measurements are in agreement with the standard model predictions. For the first time, the phase ϕs is measured independently for each polarization state of the K+K- system and shows no evidence for polarization dependence.

Measurement of the semileptonic CP asymmetry in B0-B[over ¯]0 mixing

The semileptonic CP asymmetry in B0-B[over ¯]0 mixing, a(sl)(d), is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0  fb-1, recorded by the LHCb experiment. Semileptonic B0 decays are reconstructed in the inclusive final states D-μ+ and D*-μ+, where the D- meson decays into the K+π-π- final state and the D*- meson into the D[over ¯]0(→K+π-)π- final state. The asymmetry between the numbers of D(*)-μ+ and D(*)+μ- decays is measured as a function of the decay time of the B0 mesons. The CP asymmetry is measured to be a(sl)(d)=(-0.02±0.19±0.30)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of a(sl)(d) to date and is consistent with the prediction from the standard model.

Nicotiana small RNA sequences support a host genome origin of cucumber mosaic virus satellite RNA

Satellite RNAs (satRNAs) are small noncoding subviral RNA pathogens in plants that depend on helper viruses for replication and spread. Despite many decades of research, the origin of satRNAs remains unknown. In this study we show that a β-glucuronidase (GUS) transgene fused with a Cucumber mosaic virus (CMV) Y satellite RNA (Y-Sat) sequence (35S-GUS:Sat) was transcriptionally repressed in N. tabacum in comparison to a 35S-GUS transgene that did not contain the Y-Sat sequence. This repression was not due to DNA methylation at the 35S promoter, but was associated with specific DNA methylation at the Y-Sat sequence. Both northern blot hybridization and small RNA deep sequencing detected 24-nt siRNAs in wild-type Nicotiana plants with sequence homology to Y-Sat, suggesting that the N. tabacum genome contains Y-Sat-like sequences that give rise to 24-nt sRNAs capable of guiding RNA-directed DNA methylation (RdDM) to the Y-Sat sequence in the 35S-GUS:Sat transgene. Consistent with this, Southern blot hybridization detected multiple DNA bands in Nicotiana plants that had sequence homology to Y-Sat, suggesting that Y-Sat-like sequences exist in the Nicotiana genome as repetitive DNA, a DNA feature associated with 24-nt sRNAs. Our results point to a host genome origin for CMV satRNAs, and suggest novel approach of using small RNA sequences for finding the origin of other satRNAs.

Precision measurement of the mass and lifetime of the Ξb⁻ baryon

We report on measurements of the mass and lifetime of the Ξ(b)⁻ baryon using about 1800 Ξ(b)⁻ decays reconstructed in a proton-proton collision data set corresponding to an integrated luminosity of 3.0  fb⁻¹ collected by the LHCb experiment. The decays are reconstructed in the Ξ(b)⁻→Ξ(c)⁰π⁻, Ξ(c)⁰→pK⁻K⁻π⁺ channel and the mass and lifetime are measured using the Λ(b)⁰→Λ(c)⁺π⁻ mode as a reference. We measure M(Ξ(b)⁻)-M(Λ(b)⁰)=178.36±0.46±0.16  MeV/c², (τ(Ξ(b)⁻)/τ(Λ(b)⁰)=1.089±0.026±0.011, where the uncertainties are statistical and systematic, respectively. These results lead to a factor of 2 better precision on the Ξ(b)⁻ mass and lifetime compared to previous best measurements, and are consistent with theoretical expectations.

Measurement of the CP-violating phase ϕs in Bs(0)→Ds(+)Ds(-) decays

We present a measurement of the CP-violating weak mixing phase ϕs using the decay Bs(0)→Ds(+)Ds(-) in a data sample corresponding to 3.0 fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint |λ|=1 to allow for the presence of CP violation in decay, yields ϕs=0.02±0.17(stat)±0.02(syst)  rad, |λ|=0.91(-0.15)(+0.18)(stat)±0.02(syst). This result is consistent with the standard model expectation.

Identification of pathologically small fetuses using customized, ultrasound and population-based growth norms

OBJECTIVES

Fetal growth restriction is a strong risk factor for stillbirth. We compared the performance of three fetal growth curves - customized, ultrasound (Hadlock) and population - in identifying abnormally grown fetuses at risk of stillbirth.

METHODS

We performed a case-control study of singleton stillbirths (delivered between 2000 and 2010) at one center. Four liveborn controls were randomly identified for each stillbirth. Ultrasound-estimated fetal weight within 1 month prior to delivery was used to calculate growth percentiles for each fetus using three fetal growth norms. Sensitivities and odds ratios for stillbirth, as well as odds of abnormal growth according to formula, were calculated.

RESULTS

There were 49 stillbirths and 197 live births. Using the customized norms, growth of the fetuses destined to be stillborn was bimodal, with both more small-for-gestational-age (SGA; < 10(th) percentile) and large-for-gestational-age (LGA; ≥ 90(th) percentile) fetuses. Odds of being abnormally grown were significantly higher using ultrasound compared with population norms (P = 0.02) but were not statistically different using ultrasound and customized norms (P = 0.21). Sensitivity for identification of SGA on ultrasound as a predictor of stillbirth was higher using customized (39%; 95% CI, 24-54%) or ultrasound (33%; 95% CI, 19-47%), rather than population (14%; 95% CI, 4-25%), norms.

CONCLUSIONS

Among fetuses destined to be stillborn, customized and ultrasound norms identified a greater proportion of both SGA and LGA estimated fetal weights. The customized norms performed best in identifying death among SGA fetuses. These results should be interpreted within the limitations of the study design.

Measurement of the B¯s⁰ meson lifetime in Ds⁺π⁻ decays

We present a measurement of the ratio of the B¯s⁰ meson lifetime, in the flavor-specific decay to Ds⁺π⁻, to that of the B¯⁰ meson. The pp collision data used correspond to an integrated luminosity of 1  fb(-1), collected with the LHCb detector, at a center-of-mass energy of 7 TeV. Combining our measured value of 1.010±0.010±0.008 for this ratio with the known B¯⁰ lifetime, we determine the flavor-specific B¯s⁰ lifetime to be τ(B¯s⁰ )=1.535±0.015±0.014  ps, where the uncertainties are statistical and systematic, respectively. This is the most precise measurement to date, and is consistent with previous measurements and theoretical predictions.

Observation of overlapping spin-1 and spin-3 D0K- resonances at mass 2.86 GeV/c2

The resonant substructure of B(s)(0) → D(0)K(-)π(+) decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collision data recorded by the LHCb detector. An excess at m(D(0)K(-))≈ 2.86 GeV/c(2) is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the D(sJ)*(2860)(-) state previously observed in inclusive e(+)e(-) → D(0)K(-)X and pp → D(0)K(-)X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the D(s2)*(2573)(-) meson are measured, giving the most precise determinations to date.

Test of lepton universality using b+ → K+ℓ+ℓ- decays

A measurement of the ratio of the branching fractions of the B(+) → K(+)μ(+)μ(-) and B(+) → K(+)e(+)e(-) decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb(-1), recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q(2) < 6 GeV(2)/c(4) is measured to be 0.745(-0.074)(+0.090)(stat) ± 0.036(syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the standard model prediction within 2.6 standard deviations.

First observation of a baryonic Bc+ decay

A baryonic decay of the B(c)(+) meson, B(c)(+) → J/ψppπ(+), is observed for the first time, with a significance of 7.3 standard deviations, in pp collision data collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb(-1) taken at center-of-mass energies of 7 and 8 TeV. With the B(c)(+) → J/ψπ(+) decay as the normalization channel, the ratio of branching fractions is measured to be B(B(c)(+) → J/ψppπ(+))/B(B(c)(+) → J/ψπ(+)) = 0.143(-0.034)(+0.039)(stat) ± 0.013(syst). The mass of the B(c)(+) meson is determined as M(B(c)(+) = 6274.0 ± 1.8(stat) ± 0.4(syst) MeV/c(2), using the B(c)(+) → J/ψppπ(+) channel.

Evidence for CP violation in B+ → ppK+ decays

Three-body B+ → ppK+ and B(+) → ppπ(+) decays are studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV. Evidence of CP violation in the B(+) → ppK(+) decay is found in regions of the phase space, representing the first measurement of this kind for a final state containing baryons. Measurements of the forward-backward asymmetry of the light meson in the pp rest frame yield A(FB)(ppK(+),m(pp)<2.85 GeV/c(2)) = 0.495 ± 0.012 (stat) ± 0.007 (syst) and A(FB)(ppπ(+),m(pp) <2.85 GeV/c(2)) = -0.409 ± 0.033 (stat) ± 0.006 (syst). In addition, the branching fraction of the decay B(+) → Λ(1520)p is measured to be B(B(+) → Λ(1520)p) = (3.15 ± 0.48 (stat) ± 0.07 (syst) ± 0.26 (BF)) × 10(-7), where BF denotes the uncertainty on secondary branching fractions.

DNA demethylases target promoter transposable elements to positively regulate stress responsive genes in Arabidopsis

Background

DNA demethylases regulate DNA methylation levels in eukaryotes. Arabidopsis encodes four DNA demethylases, DEMETER (DME), REPRESSOR OF SILENCING 1 (ROS1), DEMETER-LIKE 2 (DML2), and DML3. While DME is involved in maternal specific gene expression during seed development, the biological function of the remaining DNA demethylases remains unclear.

Results

We show that ROS1, DML2, and DML3 play a role in fungal disease resistance in Arabidopsis. A triple DNA demethylase mutant, rdd (ros1 dml2 dml3), shows increased susceptibility to the fungal pathogen Fusarium oxysporum. We identify 348 genes differentially expressed in rdd relative to wild type, and a significant proportion of these genes are downregulated in rdd and have functions in stress response, suggesting that DNA demethylases maintain or positively regulate the expression of stress response genes required for F. oxysporum resistance. The rdd-downregulated stress response genes are enriched for short transposable element sequences in their promoters. Many of these transposable elements and their surrounding sequences show localized DNA methylation changes in rdd, and a general reduction in CHH methylation, suggesting that RNA-directed DNA methylation (RdDM), responsible for CHH methylation, may participate in DNA demethylase-mediated regulation of stress response genes. Many of the rdd-downregulated stress response genes are downregulated in the RdDM mutants nrpd1 and nrpe1, and the RdDM mutants nrpe1 and ago4 show enhanced susceptibility to F. oxysporum infection.

Conclusions

Our results suggest that a primary function of DNA demethylases in plants is to regulate the expression of stress response genes by targeting promoter transposable element sequences.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-014-0458-3) contains supplementary material, which is available to authorized users.

First measurement of the charge asymmetry in beauty-quark pair production

The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb system. The results obtained are A(C)(bb))(40<M(bb))<75 GeV/c(2)) = 0.4 ± 0.4 ± 0.3%, A(C)(bb))(75<M(bb)) < 105 GeV/c(2)) = 2.0 ± 0.9 ± 0.6%, A(C)(bb)(M(bb)) > 105 GeV/c(2)) = 1.6 ± 1.7 ± 0.6%, where A(C)(bb)) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < η < 4, E(T) >20 GeV, and have an opening angle in the transverse plane Δ ϕ > 2.6 rad. These measurements are consistent with the predictions of the standard model.

Precision measurement of the mass and lifetime of the Ξ(b)(0) baryon

Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb(-1) collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 Ξ(b)(0) → Ξ(c)(+)π(-), Ξ(c)(+)) → pK(-)π(+) signal decays are reconstructed. From this sample, the first measurement of the Ξ(b)(0) baryon lifetime is made, relative to that of the Λ(b)(0) baryon. The mass differences M(Ξ(b)(0))-M(Λ(b)(0)) and M(Ξ(c)(+))-M(Λ(c)(+)) are also measured with precision more than 4 times better than the current world averages. The resulting values are τ(Ξ(b)(0))/τ(Λ)(b)(0)) = 1.006 ± 0.018 ± 0.010,M(Ξ(b)(0))-M(Λ(b)(0)) = 172.44 ± 0.39 ± 0.17 MeV/c(2),M(Ξ(c)(+))-M(Λ(c)(+)) = 181.51 ± 0.14 ± 0.10 MeV/c(2),where the first uncertainty is statistical and the second is systematic. The relative rate of Ξ(b)(0) to Λ(b)(0) baryon production is measured to be f(Ξ)(b)(0))/f(Λ)(b)(0))B(Ξ(b)(0) → Ξ(c)(+)π(-))/B(Λ(b)(0) → Λ(c)(+)π(-))B(Ξ(c)(+) → pK(-)π(+))/B(Λ(c)(+) → pK(-)}π(+)) = (1.88 ± 0.04 ± 0.03) × 10(-2),where the first factor is the ratio of fragmentation fractions, b → Ξ(b)(0) relative to b → Λ(b)(0). Relative production rates as functions of transverse momentum and pseudorapidity are also presented.

Observation of the resonant character of the Z(4430)(-) state

Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3  fb^{-1} collected with the LHCb detector. The data cannot be described with K^{+}π^{-} resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)^{-}→ψ^{'}π^{-} component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)^{-} amplitude with the ψ^{'}π^{-} mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1^{+}.

Observation of photon polarization in the b→sγ transition

This Letter presents a study of the flavor-changing neutral current radiative B±→K±π∓π±γ decays performed using data collected in proton-proton collisions with the LHCb detector at 7 and 8 TeV center-of-mass energies. In this sample, corresponding to an integrated luminosity of 3  fb-1, nearly 14 000 signal events are reconstructed and selected, containing all possible intermediate resonances with a K±π∓π± final state in the [1.1,1.9]  GeV/c2 mass range. The distribution of the angle of the photon direction with respect to the plane defined by the final-state hadrons in their rest frame is studied in intervals of K±π∓π± mass and the asymmetry between the number of signal events found on each side of the plane is obtained. The first direct observation of the photon polarization in the b→sγ transition is reported with a significance of 5.2σ.

Search for Majorana neutrinos in B- → π+ μ- μ- decays

A search for heavy Majorana neutrinos produced in the B- → π+ μ- μ- decay mode is performed using 3  fb(-1) of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV at the LHC. Neutrinos with masses in the range 250 to 5000 MeV and lifetimes from zero to 1000 ps are probed. In the absence of a signal, upper limits are set on the branching fraction B(B- → π+ μ- μ-) as functions of neutrino mass and lifetime. These limits are on the order of 10(-9) for short neutrino lifetimes of 1 ps or less. Limits are also set on the coupling between the muon and a possible fourth-generation neutrino.

Measurement of the Bs(0) → Ds-Ds+ and Bs(0) → D-Ds+ effective lifetimes

The first measurement of the effective lifetime of the B(s)(0) meson in the decay B(s)(0) → Ds-Ds+ is reported using a proton-proton collision data set, corresponding to an integrated luminosity of 3 fb(-1), collected by the LHCb experiment. The measured value of the B(s)(0) → Ds-Ds+ effective lifetime is 1.379 ± 0.026 ± 0.017 ps, where the uncertainties are statistical and systematic, respectively. This lifetime translates into a measurement of the decay width of the light B(s)(0) mass eigenstate of ΓL = 0.725 ± 0.014 ± 0.009 ps(-1). The B(s)(0) lifetime is also measured using the flavor-specific B(s)(0)→ D-Ds+ decay to be 1.52 ± 0.15 ± 0.01 ps.

Observation of B(s)(0) → J/ψ f1(1285) decays and measurement of the f1(1285) mixing angle

Decays of B(s)(0) and B(0) mesons into J/ψ π+π-π+π- final states, produced in pp collisions at the LHC, are investigated using data corresponding to an integrated luminosity of 3 fb-1 collected with the LHCb detector. B(s)(0) → J/ψ f1(1285) decays are seen for the first time, and the branching fractions are measured. Using these rates, the f1(1285) mixing angle between strange and nonstrange components of its wave function in the qq structure model is determined to be ±(24.0-2.6-0.8+3.1+0.6)°. Implications on the possible tetraquark nature of the f1(1285) are discussed.

In Nicotiana species, an artificial microRNA corresponding to the virulence modulating region of Potato spindle tuber viroid directs RNA silencing of a soluble inorganic pyrophosphatase gene and the development of abnormal phenotypes

Potato spindle tuber viroid (PSTVd) is a small non-protein-coding RNA pathogen that can induce disease symptoms in a variety of plant species. How PSTVd induces disease symptoms is a long standing question. It has been suggested that PSTVd-derived small RNAs (sRNAs) could direct RNA silencing of a targeted host gene(s) resulting in symptom development. To test this, we expressed PSTVd sequences as artificial microRNAs (amiRNAs) in Nicotiana tabacum and Nicotiana benthamiana. One amiRNA, amiR46 that corresponds to sequences within the PSTVd virulence modulating region (VMR), induced abnormal phenotypes in both Nicotiana species that closely resemble those displayed by PSTVd infected plants. In N. tabacum amiR46 plants, phenotype severity correlated with amiR46 accumulation and expression down-regulation of the bioinformatically-identified target gene, a Nicotiana soluble inorganic pyrophosphatase (siPPase). Taken together, our phenotypic and molecular analyses suggest that disease symptom development in Nicotiana species following PSTVd infection results from sRNA-directed RNA silencing of the host gene, siPPase.

Measurements of indirect CP asymmetries in D0 → K- K+ and D0 → π- π+ decays

A study of indirect CP violation in D0 mesons through the determination of the parameter AΓ is presented using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0  fb(-1), collected with the LHCb detector and recorded at the center-of-mass energy of 7 TeV at the LHC. The parameter AΓ is the asymmetry of the effective lifetimes measured in decays of D0 and D0 mesons to the CP eigenstates K- K+ and π- π+. Fits to the data sample yield AΓ(KK)=(-0.35±0.62±0.12)×10(-3) and AΓ(ππ)=(0.33±1.06±0.14)×10(-3), where the first uncertainties are statistical and the second systematic. The results represent the world's best measurements of these quantities. They show no difference in AΓ between the two final states and no indication of CP violation.

Measurement of CP violation in the phase space of B± → K+ K- π± and B± → π+ π- π± decays

The charmless decays B± → K+ K- π± and B± → π+ π- π± are reconstructed in a data set of pp collisions with an integrated luminosity of 1.0  fb(-1) and center-of-mass energy of 7 TeV, collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured to be A(CP)(B± → K+ K- π±) = -0.141±0.040  (stat)±0.018 (syst)±0.007(J/ψ K±) and A(CP)(B± → π+ π- π±) = 0.117±0.021 (stat)±0.009 (syst)±0.007(J/ψ K±), where the third uncertainty is due to the CP asymmetry of the B± → J/ψK± reference mode. In addition to the inclusive CP asymmetries, larger asymmetries are observed in localized regions of phase space.

Measurement of D0-D0 mixing parameters and search for CP violation using D0 → K+ π- decays

Measurements of charm mixing parameters from the decay-time-dependent ratio of D0 → K+ π- to D0 → K- π+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3  fb(-1) of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP ) symmetry, the mixing parameters are determined to be x'2=(5.5±4.9)×10(-5), y'=(4.8±1.0)×10(-3), and RD=(3.568±0.066)×10(-3). Allowing for CP violation, the measurement is performed separately for D0 and D0 mesons yielding AD=(-0.7±1.9)%, for the direct CP-violating asymmetry, and 0.75<|q/p|<1.24 at the 68.3% confidence level, for the parameter describing CP violation in mixing. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.