How insects promote crop pollination remains poorly understood in terms of the contribution of functional trait differences between species. We used meta-analyses to test for correlations between ...community abundance, species richness and functional trait metrics with oilseed rape yield, a globally important crop. While overall abundance is consistently important in predicting yield, functional divergence between species traits also showed a positive correlation. This result supports the complementarity hypothesis that pollination function is maintained by non-overlapping trait distributions. In artificially constructed communities (mesocosms), species richness is positively correlated with yield, although this effect is not seen under field conditions. As traits of the dominant species do not predict yield above that attributed to the effect of abundance alone, we find no evidence in support of the mass ratio hypothesis. Management practices increasing not just pollinator abundance, but also functional divergence, could benefit oilseed rape agriculture.
The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of ...quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We exploit Atacama Large Millimeter Array (ALMA) 870 μm observations of sub-millimetre sources in the Extended Chandra Deep Field South to investigate the far-infrared properties of high-redshift ...sub-millimetre galaxies (SMGs). Using the precisely located 870 μm ALMA positions of 99 SMGs, together with 24μm and radio imaging, we deblend the Herschel/SPIRE imaging to extract their far-infrared fluxes and colours. The median redshifts for ALMA LESS (ALESS) SMGs which are detected in at least two SPIRE bands increases with wavelength of the peak in their spectral energy distributions (SEDs), with z = 2.3 ± 0.2, 2.5 ± 0.3 and 3.5 ± 0.5 for the 250, 350 and 500 μm peakers, respectively. 34 ALESS SMGs do not have a >3σ counterpart at 250, 350 or 500 μm. These galaxies have a median photometric redshift derived from the rest-frame UV–mid-infrared SEDs of z = 3.3 ± 0.5, which is higher than the full ALESS SMG sample; z = 2.5 ± 0.2. We estimate the far-infrared luminosities and characteristic dust temperature of each SMG, deriving L
IR = (3.0 ± 0.3) × 1012 L⊙ (SFR = 300 ± 30 M⊙ yr−1) and T
d = 32 ± 1 K. The characteristic dust temperature of these high-redshift SMGs is ΔT
d = 3–5 K lower than comparably luminous galaxies at z = 0, reflecting the more extended star formation in these systems. We show that the contribution of S
870 μm ≥ 1 mJy SMGs to the cosmic star formation budget is 20 per cent of the total over the redshift range z ∼ 1–4. Adopting an appropriate gas-to-dust ratio, we estimate a typical molecular mass of the ALESS SMGs of
$M_{\rm H_2}$
= (4.2 ± 0.4) × 1010 M⊙. Finally, we show that SMGs with S
870 μm > 1 mJy (L
IR ≳ 1012 L⊙) contain ∼ 10 per cent of the z ∼ 2 volume-averaged H2 mass density.
Trapped antihydrogen Hangst, J. S; Andresen, G. B; Ashkezari, M. D ...
Nature (London),
12/2010, Volume:
468, Issue:
7324
Journal Article
Peer reviewed
Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission ...tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 1014 for the frequency of the 1s-to-2s transition), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 107 antiprotons and 7 × 108 positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4 ± 1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Atoms made of a particle and an antiparticle are unstable, usually surviving less than a microsecond. Antihydrogen, made entirely of antiparticles, is believed to be stable, and it is this longevity ...that holds the promise of precision studies of matter-antimatter symmetry. We have recently demonstrated trapping of antihydrogen atoms by releasing them after a confinement time of 172 ms. A critical question for future studies is: how long can anti-atoms be trapped? Here, we report the observation of anti-atom confinement for 1,000 s, extending our earlier results by nearly four orders of magnitude. Our calculations indicate that most of the trapped anti-atoms reach the ground state. Further, we report the first measurement of the energy distribution of trapped antihydrogen, which, coupled with detailed comparisons with simulations, provides a key tool for the systematic investigation of trapping dynamics. These advances open up a range of experimental possibilities, including precision studies of charge-parity-time reversal symmetry and cooling to temperatures where gravitational effects could become apparent. PUBLICATION ABSTRACT
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IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
OBJECTIVE:The aim of this study was to investigate the association between short-term outcome indicators and long-term survival after esophagogastric resections.
SUMMARY BACKGROUND DATA:Short-term ...outcome indicators are often used to compare performance between care providers. Some short-term outcome indicators concern the direct quality of care, that is, complications, others are used because they are expected to be associated with long-term outcomes.
METHOD:For this national cohort study, all patients who underwent esophagectomy or gastrectomy for cancer with curative intent between 2011 and 2016 and were registered in the Dutch Upper gastrointestinal Cancer Audit were included. Primary outcome was conditional survival (under the condition of surviving the first postoperative 30 days and hospital admission). Cox regression modeling was used to study the independent association between “textbook outcome” with survival. “Textbook outcome,” a composite quality indicator, was defined as a pathological complete resection with at least 15 retrieved lymph nodes, an uneventful postoperative course, and no hospital readmission.
RESULTS:In total, 4414 and 2943 patients with esophageal or gastric cancer, respectively, were included. The 1-, 2-, and 3-year overall survival rates were 76%, 62%, and 54%, and 71%, 56%, and 49% for esophageal and gastric cancer, respectively. Textbook outcome was achieved in 33% and 35% of patients respectively. “Textbook outcome” was independently associated with longer conditional survival hazard ratio0.75 (95% confidence interval, 0.68–0.84) and 0.69 (0.60–0.79), respectively.
CONCLUSION:This study showed that the short-term outcome indicator textbook outcome is associated with long-term overall survival and therefore may accentuate the importance of using these indicators in clinical audits.
At the historic Shelter Island Conference on the Foundations of Quantum Mechanics in 1947, Willis Lamb reported an unexpected feature in the fine structure of atomic hydrogen: a separation of the 2S
...and 2P
states
. The observation of this separation, now known as the Lamb shift, marked an important event in the evolution of modern physics, inspiring others to develop the theory of quantum electrodynamics
. Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. Mirroring the historical development of quantum atomic physics in the twentieth century, modern measurements on anti-atoms represent a unique approach for testing quantum electrodynamics and the foundational symmetries of the standard model. Here we report measurements of the fine structure in the n = 2 states of antihydrogen, the antimatter counterpart of the hydrogen atom. Using optical excitation of the 1S-2P Lyman-α transitions in antihydrogen
, we determine their frequencies in a magnetic field of 1 tesla to a precision of 16 parts per billion. Assuming the standard Zeeman and hyperfine interactions, we infer the zero-field fine-structure splitting (2P
-2P
) in antihydrogen. The resulting value is consistent with the predictions of quantum electrodynamics to a precision of 2 per cent. Using our previously measured value of the 1S-2S transition frequency
, we find that the classic Lamb shift in antihydrogen (2S
-2P
splitting at zero field) is consistent with theory at a level of 11 per cent. Our observations represent an important step towards precision measurements of the fine structure and the Lamb shift in the antihydrogen spectrum as tests of the charge-parity-time symmetry
and towards the determination of other fundamental quantities, such as the antiproton charge radius
, in this antimatter system.
Background
For esophageal cancer, the number of retrieved lymph nodes (LNs) is often used as a quality indicator. The aim of this study is to analyze the number of retrieved LNs in The Netherlands, ...assess factors associated with LN yield, and explore the association with short-term outcomes. This is a population-based study on lymph node retrieval in patients with esophageal cancer, presenting results from the Dutch Upper Gastrointestinal Cancer Audit.
Study Design
For this retrospective national cohort study, patients with esophageal carcinoma who underwent esophagectomy between 2011 and 2016 were included. The primary outcome was the number of retrieved LNs. Univariable and multivariable regression analyses were used to test for association with ≥ 15 LNs.
Patients and Results
3970 patients were included. Between 2011 and 2016, the median number of LNs increased from 15 to 20. Factors independently associated with ≥ 15 LNs were: 0–10 kg preoperative weight loss (versus: unknown weight loss, odds ratio 95% confidence interval: 0.71 0.57–0.88), Charlson score 0 (versus: Charlson score 2: 0.76 0.63–0.92), cN2 category (reference: cN0, 1.32 1.05–1.65), no neoadjuvant therapy and neoadjuvant chemotherapy (reference: neoadjuvant chemoradiotherapy, 1.73 1.29–2.32 and 2.15 1.54–3.01), minimally invasive transthoracic (reference: open transthoracic, 1.46 1.15–1.85), open transthoracic (versus open and minimally invasive transhiatal, 0.29 0.23–0.36 and 0.43 0.32–0.59), hospital volume of 26–50 or > 50 resections/year (reference: 0–25, 1.94 1.55–2.42 and 3.01 2.36–3.83), and year of surgery reference: 2011, odds ratios (ORs) 1.48, 1.53, 2.28, 2.44, 2.54. There was no association of ≥ 15 LNs with short-term outcomes.
Conclusions
The number of LNs retrieved increased between 2011 and 2016. Weight loss, Charlson score, cN category, neoadjuvant therapy, surgical approach, year of resection, and hospital volume were all associated with increased LN yield. Retrieval of ≥ 15 LNs was not associated with increased postoperative morbidity/mortality.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The optimal time between end of neoadjuvant chemoradiotherapy (nCRT) and oesophagectomy is unknown. The aim of this study was to assess the association between this interval and pathologic complete ...response rate (pCR), morbidity and 30-day/in-hospital mortality.
Patients with oesophageal cancer treated with nCRT and surgery between 2011 and 2016 were selected from a national database: the Dutch Upper Gastrointestinal Cancer Audit (DUCA). The interval between end of nCRT and surgery was divided into six periods: 0–5 weeks (n = 157;A), 6–7 weeks (n = 878;B), 8–9 weeks (n = 972;C), 10–12 weeks (n = 720;D), 13–14 weeks (n = 195;E) and 15 or more weeks (n = 180;F). The association between these interval groups and outcomes was investigated using univariable and multivariable analysis with group C (8–9 weeks) as reference.
In total, 3102 patients were included. The pCR rate for the groups A to F was 31%, 28%, 26%, 31%, 40% and 37%, respectively. A longer interval was associated with a higher probability of pCR (≥10 weeks for adenocarcinoma: odds ratio 95% confidence interval: 1.35 1.00–1.83, 1.95 1.24–3.07, 1.64 0.99–2.71 and ≥13 weeks for squamous cell carcinoma: 2.86 1.23–6.65, 2.67 1.29–5.55. Patients operated ≥10 weeks after nCRT had the same probability for intraoperative/postoperative complications. Patients from groups D and F had a higher 30-day/in-hospital mortality (1.80 1.08–3.00, 3.19 1.66–6.14).
An interval of ≥10 weeks for adenocarcinoma and ≥13 weeks for squamous cell carcinoma between nCRT and oesophagectomy was associated with a higher probability of having a pCR. Longer intervals were not associated with intraoperative/postoperative complications. The 30-day/in-hospital mortality was higher in patients with extended intervals (10–12 and ≥15 weeks); however, this might have been due to residual confounding.
•The interval between end of nCRT and oesophagectomy for cancer is associated with pathological response.•An extended interval is associated with higher pathological complete response rate.•These intervals are not associated with intraoperative and postoperative complications.•Higher 30-day/in-hospital mortality was observed for intervals of 10–12 and 15 or more weeks.•The higher 30-day/in-hospital mortality might be due to selection bias and residual confounding.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged ...particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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