From the Cover: The fingerprint of climate trends on European crop yields

Europe has experienced a stagnation of some crop yields since the early 1990s as well as statistically significant warming during the growing season. Although it has been argued that these two are causally connected, no previous studies have formally attributed long-term yield trends to a changing climate. Here, we present two statistical tests based on the distinctive spatial pattern of climate change impacts and adaptation, and explore their power under a range of parameter values. We show that statistical power for the identification of climate change impacts is high in many settings, but that power for identifying adaptation is almost always low. Applying these tests to European agriculture, we find evidence that long-term temperature and precipitation trends since 1989 have reduced continent-wide wheat and barley yields by 2.5% and 3.8%, respectively, and have slightly increased maize and sugar beet yields. These averages disguise large heterogeneity across the continent, with regions around the Mediterranean experiencing significant adverse impacts on most crops. This result means that climate trends can account for ∼10% of the stagnation in European wheat and barley yields, with likely explanations for the remainder including changes in agriculture and environmental policies.Europe has experienced a stagnation of yields for some crops, particularly wheat and barley, with a plateau since the early to mid-1990s (Fig. 1A) (1, 2). Explanations for this stagnation have focused on changing agricultural policy and, to a lesser extent, on shifting climate patterns (3, 4). Much of Europe saw the introduction of more stringent environmental policies during the 1990s, as well as the decoupling of subsidy payments from farm production in the European Union, both of which would be expected to lower the intensity of cereal production (5, 6). In addition, warming trends in the region have been large relative to natural variability and could be expected to negatively affect yields, particularly in southern Europe (SI Appendix, Fig. S1) (7, 8).Open in a separate windowFig. 1.Patterns and time evolution of crop yields in Europe and the predicted impacts of climate trends. (A) Area-weighted yields of the four crops examined in this paper for the countries included in the study, 1960–2010 (SI Appendix, Table S1) (17). (B–E) Maps of the observed linear trend in yield in 1989–2009 for wheat (B), maize (C), barley (D), and sugar beet (E) (25). Maps of the expected change in yield based on growing-season temperature and precipitation trends in 1989–2009 (27, 28) and the yield response functions described by Moore and Lobell (8) (SI Appendix, Figs. S3 and S4) for wheat (F), maize (G), barley (H), and sugar beet (I). White shows areas not included in the study due to insufficient data.Existing empirical evidence for either explanation is typically weak, taking the form of coincidence in the direction and timing of expected climate or policy effects with yield trends, so the relative importance of these mechanisms has not been rigorously demonstrated (3, 9). More persuasive detection and attribution studies instead identify impacts using a distinctive spatial pattern of trends associated with climate change forcing (10, 11). Because the spatial distribution of long-term trends is less likely to be correlated with other variables, these studies are better able to make a case for climate’s causal effect on the outcome of interest. Fig. 1 B–E shows the observed trends in yields of wheat, maize, barley, and sugar beet in Europe between 1989 and 2009. Fig. 1 F–I shows the trends in yield that would have been expected given observed changes in growing-season temperature and precipitation and the sensitivity of crops to those changes (8). Observed trends are both more positive and more spatially heterogeneous than the predicted trends, which would be expected given that the latter do not include the effects of technological improvements or of changing economic or policy conditions. Nevertheless, formal statistical tests can reveal whether or not the distinctive pattern, or fingerprint, of climate trend impacts is embedded within the observed pattern of long-term yield trends.Formal detection of a climate change signal and the attribution of that signal to anthropogenic greenhouse gas emissions has been successful in many physical and some biological systems (10–12). However, few studies have attributed changing yield pattern to climate trends. This analysis is complicated by two factors. First, the expected response of agriculture to a given temperature or precipitation forcing is determined by an imperfectly known response function. This response uncertainty must be accounted for in determining whether or not climate change has had a statistically discernable impact. Second, farmers may or may not be adapting to the climate change they have experienced, creating additional uncertainty in the expected response of agriculture to climate forcing (13). This potential for adaptation means there are two response functions relevant to the detection (and prediction) of climate change impacts: the short-run response function that includes limited or no adaptation, and the long-run response function that includes full adaptation (8).In this paper, we first develop two general statistical tests that can be applied to the detection of impacts and adaptation in any managed system affected by climate change and report the power of these tests under a range of parameter values. We then apply these tests to Europe to determine whether climate trends have affected yields and, if so, to what extent these impacts can explain the stagnation of European cereal yields.     

The Effect of Long-term Dressing with Calcium Hydroxide on the Fracture Susceptibility of Teeth

Introduction

Calcium hydroxide has been widely used to treat immature teeth to achieve periodontal healing and to promote the formation of an apical barrier. However, retrospective clinical studies have shown a high incidence of cervical root fractures with long-term calcium hydroxide dressing. The alkalinity of calcium hydroxide has been suggested to weaken the root. In vitro studies using ovine teeth show conflicting results on fracture strength of dentine, although different commercial products may have influenced the results. The purpose of this study was to investigate the effects of 2 commercial products used in prior studies (Calasept Plus and UltraCal XS), as well as a new product (Calmix) that uses a nonaqueous vehicle that allows for a higher pH, on the fracture strength of dentine over time.

Dual-scale TiO2 and SiO2 particles in combination with a fluoroalkylsilane and polydimethylsiloxane superhydrophobic/superoleophilic coating for efficient solvent–water separation

Surfaces that have unique wettabilities and are simultaneously superhydrophobic with water contact angles > 150°, and superoleophilic with oil contact angles < 5°, are of critical importance in the oil/solvent–water separation field. This work details the facile preparation of highly efficient oil–water separation devices that successfully combine hierarchical surface roughening particles and low surface energy components with porous substrates. Coatings were generated using TiO₂ and hydrophobic-SiO₂ micro/nanoparticle loadings which were then embedded within polydimethylsiloxane, commercially known as Sylgard® 184, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS) polymer mixtures. The resulting slurries were dip coated onto copper meshes with varying pore diameters (30, 60 and 100 meshes had 595, 250 and 149 μm pore dimensions respectively). Functional testing proved that mesh substrates coated in the lowest Sylgard® 184 : FAS polymer ratio formulations displayed heightened water repellency and retained their superoleophilic properties upon repeat testing. The largest average water contact angle of 145 ± 1°, was recorded on a copper 30 mesh substrate with a coating comprising H-SiO₂ microparticles and TiO₂ nanoparticles in a 1 : 9 polymer mixture of Sylgard® and FAS. The coating''s extreme oil affinity was supported by high solvent–water separation efficiencies (≥99%) which withstood numerous testing/washing cycles.

Surfaces that have unique wettabilities and are simultaneously superhydrophobic with water contact angles > 150°, and superoleophilic with oil contact angles < 5°, are of critical importance in the oil/solvent–water separation field.     

Obesity hypoventilation syndrome: a review of epidemiology, pathophysiology, and perioperative considerations

Obesity hypoventilation syndrome (OHS) is defined by the triad of obesity, daytime hypoventilation, and sleep-disordered breathing without an alternative neuromuscular, mechanical, or metabolic cause of hypoventilation. It is a disease entity distinct from simple obesity and obstructive sleep apnea. OHS is often undiagnosed but its prevalence is estimated to be 10-20% in obese patients with obstructive sleep apnea and 0.15-0.3% in the general adult population. Compared with eucapnic obese patients, those with OHS present with severe upper airway obstruction, restrictive chest physiology, blunted central respiratory drive, pulmonary hypertension, and increased mortality. The mainstay of therapy is noninvasive positive airway pressure. Currently, information regarding OHS is extremely limited in the anesthesiology literature. This review will examine the epidemiology, pathophysiology, clinical characteristics, screening, and treatment of OHS. Perioperative management of OHS will be discussed last.     

Tubo-Ovarian Abscess in Non−Sexually Active Adolescent Girls: A Case Series and Literature Review

Study ObjectiveWe investigated risk factors and common causes of tubo-ovarian abscess (TOA) in non?sexually active females in order to aid in earlier diagnosis, treatment, and improved outcomes.DesignThis is a retrospective observational case series of all non?sexually active females younger than age 25 years who were diagnosed with TOA. Review of the existing literature was also performed.SettingAcademic tertiary care children's hospital.ParticipantsTen patients meeting study inclusion criteria were identified for the study, and 33 other patients were identified in the literature.ResultsAverage age at time of diagnosis was 14 years. Average body mass index was 24 kg/m². Most presented with abdominal pain, often associated with fevers, nausea, vomiting, and diarrhea. Seven of 10 patients were treated surgically with pelvic washout (4 primarily and 3 after failing empiric antibiotic therapy). Most frequently, anaerobic gut flora were isolated on culture. All patients received broad-spectrum intravenous antibiotics, and were then discharged on a course of doxycycline and metronidazole or clindamycin. Three patients required additional admissions and multiple rounds of antibiotics due to persistent symptoms. The average length of stay was 3 days for patients treated with antibiotics only and 6 days for patients requiring surgical intervention. Six patients had complete resolution of symptoms and improvement on ultrasound within 2-4 weeks. The remainder were lost to follow-up.ConclusionThese cases, in conjunction with previous case reports, emphasize the importance of considering TOA in patients with concerning imaging or examination findings despite lack of sexual activity. Given the large proportion of cases attributable to anaerobic gut flora, treatment with antibiotics with adequate anaerobic coverage is recommended. Surgical drainage is not always necessary, but is often needed for diagnostic purposes or in patients not clinically improving with conservative measures.     

Genetic and antigenic analysis of invasive serogroup C Neisseria meningitidis in Canada: A decrease in the electrophoretic type (ET)-15 clonal type and an increase in the proportion of isolates belonging to the ET-37 (but not ET-15) clonal type during the period from 2002 to 2009

BACKGROUND:

Serogroup C meningococcal disease has been endemic in Canada since the early 1990s, with periods of hyperendemic disease documented in the past two decades. The present study characterized invasive serogroup C meningococci in Canada during the period from 2002 to 2009.

METHODS:

Serogroup C meningococci were serotyped using monoclonal antibodies. Their clonal types were identified by either multilocus enzyme electrophoresis or multilocus sequence typing.

RESULTS:

The number of invasive serogroup C Neisseria meningitidis isolates received at the National Microbiology Laboratory (Winnipeg, Manitoba) for characterization has dropped from a high of 173 isolates in 2001 to just 17 in 2009, possibly related to the introduction of the serogroup C meningococcal conjugate vaccine. Before 2006, 80% to 95% of all invasive serogroup C meningococci belonged to the electrophoreic type (ET)-15 clonal type, and the ET-37 (but not ET-15) type only accounted for up to 5% of all isolates. However, beginning in 2006, the percentage of the ET-15 clonal type decreased while the ET-37 (but not ET-15) type increased from 27% in 2006 to 52% in 2009. The percentage of invasive serogroup C isolates not belonging to either ET-15 or ET-37 also increased. Most ET-15 isolates expressed the antigenic formula of C:2a:P1.7,1 or C:2a:P1.5. In contrast, the ET-37 (but not ET-15) isolates mostly expressed the antigens of C:2a:P1.5,2 or C:2a:P1.2.

CONCLUSION:

A shift in the antigenic and clonal type of invasive serogroup C meningococi was noted. This finding suggests vigilance in the surveillance of meningoccocal disease is warranted.