text:
Home About us Editorial board Ahead of print Browse Articles Search Archives Submit article Instructions Subscribe Contacts Login
Year : 2018 | Volume : 9 | Issue : 1 | Page : 78
Pharmacological and non-pharmacological means for prevention of fractures among elderly
Auda Fares
Department of Acute Geriatric Medicine and Rehabilitation, St. Willibrord-Spital Emmerich-Rees, Germany
Date of Submission 01-Mar-2018
Date of Acceptance 05-Jul-2018
Department of Acute Geriatric Medicine and Rehabilitation, St. Willibrord-Spital Emmerich-Rees
DOI: 10.4103/ijpvm.IJPVM_114_18
Fractures are major cause of morbidity, mortality, and healthcare and social services expenditure in elderly. Fractures often have multifactorial etiologies and the condition emerges due to the interaction between the different predisposing and precipitating factors. One of the most common causes leading to fractures after minimal trauma in older people is osteoporosis. The objective of this article is to describe the clinical concept and summarize the evidence and to explain the future directions for research, focusing on specific issues related to prevent fracture in the elderly. This study reviewed the scientific literature addressing strategies for primary and secondaryprevention of fractures among elderly in the context of pharmacological and non-pharmacological means. A growing body of scientific evidence supports the use of both non-pharmacological and pharmacological interventions for the prevention of fracture. Research on these interventions has yielded positive outcomes in fracture rates. The bisphosphonates and vitamin D and calcium suppliments are the preferred therapy for prevention of osteoporotic fractures. Weight-bearing exercise and reducing home hazards have beneficial effects in reducing the incidence of falls and consequently reduce fractures. Prevention of fractures in elderly consists of therapy and prevention of osteoporosis, fall prevention, and using injury-site protection by high-risk elderly patients. Special consideration needs to be taken to reduce home hazard, and falls prevention education can be recommended to the elderly with history of fall or mobility limitations. Future research to prevent fractures in elderly population should not only concentrate on improving bone density and strength but also need to be focused on falls reduction strategies.
Keywords: Accidental falls, elderly, excercises, fracture, hip protectors, home hazards, lifestyle, osteoporosis, prevention
Fares A. Pharmacological and non-pharmacological means for prevention of fractures among elderly. Int J Prev Med 2018;9:78
Fares A. Pharmacological and non-pharmacological means for prevention of fractures among elderly. Int J Prev Med [serial online] 2018 [cited 2021 Jan 19];9:78. Available from: https://www.ijpvmjournal.net/text.asp?2018/9/1/78/241422
Fractures represent one of the most important causes of morbidity, mortality and healthcare and social services expenditure in elderly. The incidence of fractures of pelvis, hip, vertebrae, humerus, radius, and ankle increase with advance age. A fracture of elderly person often has multifactorial etiologies, and the condition emerges due to the interaction between the different predisposing and precipitating factors. One of the most common causes leading to fracture after minimal trauma in older people is osteoporosis. Evidence indicates that both pharmacological and non-pharmacological intervention methods have shown benefit in reducing the incidence of fractures in the elderly population and improving daily life activities and quality of life in survivors. Falls are one of the main causes of injury in people age 65 and older and are responsible for 56% of hospitalization for trauma and for 6% of urgent hospitalization in these age group; 5%–10% of them have fractures.[1],[2] Current evidence suggests that both falls and risk of falls are prevented in community settings by individuals regularly carrying out specific physical activities and improving the safety of their homes. Nevertheless, a decrease in fracture rate has been recently observed, owing to several factors including awareness about osteoporosis and the danger of falls. Many improvements have been introduced in the care of these patients, including improved surgical devices, earlier mobilization, prophylactic administration of anti-osteoporosis, and increased rate of admission into rehabilitation unit. In this article, we present an evaluation of current literature relating to the prevention of fractures among elderly in the context of pharmacological and non-pharmacological means.
This article was designed to review previous studies and summarize the current knowledge and controversies related to primary and secondary prevention of fractures among elderly in the context of pharmacological and non-pharmacological means. Searches were performed on MEDLINE, Cochrane Library, and Google Scholar databases from their inception to July 2017. The search was updated in June 2018. No date restrictions were placed on the search. We used the key words "Elderly, accidental falls, fracture, hip protectors, excercises, osteoporosis, prevention, lifestyle, home hazards." Studies were selected based on the following inclusion criteria: papers in English language and published in peer-reviewed journal were considered. Review articles, clinical trial, cross-sectional study, meta-analyses, letter, editorial, textbook chapters, case reports, practice guidelines, and biomechanical studies were gathered to augment overall knowledge and to identify research articles or data not obtained using the search engines. Studies dealing with fractures or fractures prevention in elderly subjects were considered. Studies dealing with surgical complications, mortality rate, surgical method, and fracture in young or children are excluded. From the search results, articles with irrelevant titles were discounted, with the remaining abstracts examined for relevance. Reference listings of the remaining articles were also searched and scrutinized for relevance.
Overview of common fractures in elderly
Worldwide, osteoporosis causes more than 9 million fractures annually, of which 1.6 million were at the hip, 1.7 million at the forearm, and 1.4 million were clinical vertebral fractures.[3] Estimates indicate that 50% of women and 20% of men over 50 years of age will experience an osteoporosis-related fracture.[4] The incidence varies substantially from one population to another. In the United States, the number of osteoporosis-related fractures was estimated to exceed 2 millionin 2005. Nonvertebral fractures were estimated to account for 73% of the total number of fractures. Women age 65 years and older accounted for 74% of all fractures.[5] In the European Union, approximately 3.5 million new fragility fractures occur annually, comprising 620,000 hip fractures, 520,000 vertebral fractures, 560,000 forearm fractures, and 1,800,000 other fractures (i.e., fractures of the pelvis, rib, humerus, tibia, fibula, clavicle, scapula, sternum, and other femoral fractures).[6] In African and Asian countries lying somewhere between. However, with the rapid increase in the ageing population and increased longevity, it has been estimated that more than 50% of hip fractures will be concentrated in Asia.
Assessment of fracture risk factors in elderly
Bone mineral density (BMD) is the standard measure for the diagnosis of osteoporosis and the assessment of fracture risk. Several additional clinical factors have been identified which contribute significantly to risk of fracture independently of BMD. These include age, sex, race, height, weight, body mass index, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis, and the use of oral glucocorticoids.[7] These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using web-based algorithm design called FRAX (Fracture Risk Assessment Tool). FRAX calculates the 10-year probability of a major osteoporotic-related fracture in the proximal part of the humerus, the wrist, or the hip or spine. In addition, BMD considers only the density of the bone and fails in measuring bone microarchitecture. Recently, a new tool to assess osteoporosis and fracture risk, called Trabecular Bone Score (TBS), has been developed. TBS is a texture parameter related to bone microarchitecture that may provide skeletal information that is not captured from the standard BMD measurement. TBS has been shown to have predictive value for fracture independent of fracture probabilities using the FRAX.[8],[9] However, some other factors, including risk of falls and poor vision, causes of secondary osteoporosis such as hypogonadism, or other risks associated with bone quality, such as chronic kidney disease, may increase fracture risk.[10] Cognitive impairment, stroke, and lack of urine control were reported to be associated with increased risk of severe fall-related fractures.[10] Measurements of biochemical bone marker levels can also be used to assess fracture risk and help select patients for therapy.[11] Vitamin D deficiency has been associated with increased fall rates and fractures.[12] Therefore, vitamin D levels' estimation can also be used to asses fracture risk. Other measurements such as serum calcium, creatinine, alkaline phosphatase, liver enzymes and complete blood count, serum protein electrophoresis, thyroid function tests, and parathyroid hormone level are useful for identifying some forms of metabolic bone diseases and exclude severe underlying illnesses.
Many drugs commonly used by elderly people have been reported to be associated with increased risk of fall-related fractures. These include antihypertensive agents, diuretics, β-blockers, sedatives and hypnotics, neuroleptics and antipsychotics, antidepressants, narcotics, and nonsteroidal anti-inflammatory drugs.[13] However, the risks and benefits need to be fully considered when initiating these medications in those at risk of falls. Reducing medication use can dramatically decrease falls. In one study, withdrawal of psychotropic medications resulted in a 66% reduction in the rate of falls.[14],[15]
Pharmacologic fracture prevention in elderly
Calcium and vitamin D
Calcium and vitamin D have long been recognized as important and required to protect bone and prevent osteoporotic fractures. Several evidence-based reviews have investigated the efficacy of vitamin D and calcium supplementation on bone loss and fracture reduction in elderly. A recent Cochrane review suggests that there is high-quality evidence that calcium combined with vitamin D results in small and significant reductions in the risk of hip fracture (16%), vertebral fracture (14%), any non-vertebral fracture (11%).[16] Similarly, another Cochrane review demonstrated that vitamin D supplementation alone is unlikely to be effective in preventing hip fracture (11 trials, 27,693 participants; risk ratio (RR) 1.12, 95% confidence interval (CI) 0.98–1.29) or any new fracture (15 trials, 28,271 participants; RR 1.03, 95% CI 0.96–1.11).[17] Treatment with calcium at a dosage of 1200 mg or more has been shown to be more effective than with doses less than 1200 mg in fracture prevention, and with vitamin D doses of 800 IU or more than with doses less than 800 IU.[18] However, it is clear from these studies that the concomitant use of calcium and vitamin D supplementation is recommended in elderly, particularly in those at risk of marginal and low vitamin D status. It is generally recommended to intake 800 IU/day of vitamin D and 1000 mg of calcium per day.[19] Nevertheless, the risks associated with calcium supplements are not uncommon in elderly patients. Recent scientific evidence, however, suggests that elevated consumption of calcium supplements may raise the risk for cardiovascular disease (CVD) and can be connected with accelerated deposit of calcium in blood-vessel walls. However, the purported CVD risk associated with total calcium intake may depend on the source of calciumintake.[20] Intake of calcium from food sources has not been shown to increase CVD risk, whereas a signal for increased risk of myocardial infarction (MI) among calcium supplement users has been reported. Food remains the best source of calcium; however, calcium supplements should be considered when dietary intake of calcium is inadequate.[21]
Bisphosphonates are potent inhibitors of osteoclasts, have an established role in improving the bone density, and prevent osteoporotic fractures. More recently, evidence shows that bisphosphonates decrease the risk of overall osteoporotic fracture [odds ratio (OR) 0.62; P < 0.001], vertebral fracture (OR 0.55; P < 0.001), and non-vertebral fracture (OR 0.73; P < 0.001) in postmenopausal women with osteoporosis.[22] This finding is similar to the results of the meta-analysis studies conducted by Zhou et al., which found that the relative risk reduction in vertebral fractures ranged from 0.55 to 0.61.[23] One large randomized study evaluated in a 2008 Cochrane review suggests 10 mg bisphosphonates per day, both clinically important and statistically significant reductions in vertebral, non-vertebral, hip, and wrist fractures.[24]
Calcitonin is a potent osteoclast inhibitor through receptors, and it has been approved for the treatment of osteoporosis and other diseases involving accelerated bone turnover. Several studies have shown its effects to reduce bone turnover, stabilize or increase bone density, preserve or improve microarchitecture, and improve mineralization.[25],[26] The effects of calcitonin on fracture prevention rate are controversial. The most relevant clinical trial to evaluate the effect of calcitonin in the prevention of fractures was the Prevent Recurrence of Osteoporotic Fractures (PROOF) study, a 5-year double-blind, randomized, placebo-controlled trial showing that salmon calcitonin nasal spray at a dosage of 200 IU/day can reduce the risk of vertebral osteoporotic fractures by 33% [relative risk (RR) = 0.67; 95% CI 0.47–0.97; P = 0.03).[27] However, the 100 and 400 IU/day dosages did not significantly reduce vertebral fracture risk. Effects on nonvertebral fractures were not significant (RR = 0.80; 95% CI 0.59–1.09; P = 0.16).[26] However, more studies are necessary to confirm these results. Neverthless, few safety concerns have been raised for calcitonin. In 2012, the European Medicines Agency suspended calcitonin nasal spray from the market and limited the duration of use of other calcitonin products due to a putative association with cancer. Current understanding of the biology and mechanism of action of salmon calcitonin does not support a role as an oncogenor tumor-accelerating agent. Such evidence is lacking in preclinical carcinogenicity, genotoxicity, and mutagenicity studies and, in general, biological plausibility. Consideration of all the available data suggests that the association between calcitonin and cancer is weak.[28] Further studies are necessary to conclude a causal association between calcitonin and cancer.
Teriparatide
Teriparatide is a potent anabolic agent used to treat osteoporosis in women or men with a high risk for bone fracture. They act by directly stimulating bone formation and improving bone mass quantity and quality. High-quality evidence showed that treatment with teriparatide increases in BMD and low incidences of new vertebral and nonvertebral fractures.[29] However, the high costs and subcutaneous administration of teriparatide make it less attractive for some olderly people with osteoporosis, although it is an effective alternative for those who have severe osteoporosis, cannot tolerate oral bisphosphonates, or who have failed other therapies.[30]
Multiple studies have shown that estrogen replacement therapy has a beneficial effect on the reduction of fractures in patients with osteoporosis. In a meta-analysis of 21 studies, estrogen therapy replacement was shown to reduce nonvertebral fractures by 27%,[31] and in another meta-analysis of 13 studies, there was a significant reduction 33% of vertebral fractures.[32] However, there is some evidence that estrogen when given together with calcium and vitamin D will be more effective in reduction of osteoporotic fractures.[33]
Selective estrogen receptor modulators
Selective estrogen receptor modulators (SERMs) have a beneficial effect on bone. These SERMs inhibited bone turnover and prevented bone loss caused by estrogen deficiency. Raloxifene, second-generation SERM, has been approved for the prevention and treatment of post-menopausal osteoporosis. A systemic review that included 15 studies reported a statistically significant increase in BMD of the lumbar spine, but not the hip region, a low incidence of vertebral fracture, decrease in markers of bone turnover, and improved hip structural geometry.[34] For lasofoxifene, another SERM, the randomized, double-blind, placebo-controlled study Postmenopausal Evaluation and Risk Reduction with Lasofoxifene (PEARL) clinical trial for vertebral fracture risk in postmenopausal women showed a 42% reduction compared with placebo (P < 0.01), and 24% reductions in the absolute incidence of nonvertebral fracture.[35] In a 3-year randomized, double-blind, placebo-controlled study (N = 7,492), bazedoxifene 20 mg and bazedoxifene 40 mg significantly (P < 0.05) reduced the risk of new vertebral fractures by 42%, compared with placebo in postmenopausal women with osteoporosis.[36] In a second 2-year extension of the 3-year in a same study, the relative risk reductions were 36.5% (P < 0.001). Bazedoxifene had no effect on the overall incidence of nonvertebral fractures (12.0%; placebo, 10.8%).[36]
A new therapeutic advance in the treatment of postmenopausal osteoporosis is denosumab. Denosumab is a human monoclonal antibody which reduces the risk of fracture by inhibiting osteoclast formation, decreasing bone resorption, and increasing BMD. In a large randomized, placebo-controlled trial, denosumb has been reducing the risk of vertebral fractures by 68% for 3 years. The risk of hip fractures was diminished by 40% and nonvertebral fractures by 20% in postmenopausal women.[37]
Non-pharmacologic fracture prevention in elderly
Hip protectors are one of multifactorial interventions for fall and fracture prevention in residential, high-risk patients. In a systematic review by Santesso et al. which included data of 14 studies (11,808 participants) conducted in nursing or residential care settings, moderate quality evidence for a small reduction in hip fracture risk (RR 0.82, 95% CI 0.67–1.00) was found; the absolute effect is 11 fewer people (95% CI from 20 fewer to 0) per 1000 having a hip fracture when provided with hip protectors.[38] However, not all elderly people with a high risk of hip fracture will agree to use hip protectors and in those who do, long-term adherence may decrease. Therefore, adherence is a major problem in assessing the effectiveness of hip protectors in preventing fractures. To increase adherence, it is necessary to educate older persons who are at risk on the dangers of hip fractures and the value of hip protectors as a preventive device. Moreover, little data are available on the cost-effectiveness of hip protectors. The most commonly reported complications with hip protectors are skin irritation. A Cochrane review of 18 trials found that the incidence of adverse events while wearing hip protectors, including skin irritation, ranged from 0% to 5%.[39]
Physical exercise has demonstrated its beneficial effects in reducing the risk of the number of fall. In a meta-analysis that included data from 25 studies, the investigators revealed that the exercise training programs prevented or reversed almost 1% of bone loss per year in both lumbar spine and femoral neck for both pre- and postmenopausal women.[40] Exercise training appears to significantly reduce fear of falling[41] and the risk and number of falls.[42] The risk and incidence of fractures are also reduced among active people.[43] Kujala et al. detected a positive association between physical activity and reduced incidence of hip fracture (hazard ratio 0.38, 95% CI 0.16–0.91).[44] In a systematic review by Cadore et al., the investigators evaluated the Effects of Different Exercise Interventions on Risk of Falls, Gait Ability, and Balance in Physically Frail Older Adults.[45] The investigators found that the mean decrease in the incidence of falls after the physical training period ranged from 22% to 58%, the mean improvement in balance ranged from 5% to 80%, the mean improvement in gait ability ranged from 4% to 50%, and the mean increase in muscle strength ranged from 6% to 60%.[46]
Some exercises such as weight-bearing exercise, especially resistance exercise, appear to have the greatest effects on BMD.[47] One study revealed that people who did resistance training had increased BMD compared with those who did not do such training. Furtheremore, several studies have shown that this type of exercise intervention can improve neuromuscular activity, muscle mass, strength, power, and functional capacity.[46] In a study conducted by Fiatarone et al., it was found that the resistance training groups improved their habitual gait velocities and stair-climbing abilities and enhanced the leg muscle strength outcomes (P < 0.001).[48] Another study revealed statistically significant improvements in the Timed Up and Go test, gait speed, after 12 weeks of resistance training that was performed three times per week.[49] Morover, Tai Chi exercises have also demonstreted improved balance, gait speed, muscle strength, and quality of life in elderly. Recent studies including a systematic review have demonstreted that Tai Chi interventions have beneficial effects in reducing the risk of falls through improving the balance.[46],[50],[51] The mean improvement in balance after Tai Chi exercise has been reported to range from 5% to 80%.[46] For the above-mentioned exercises, multicomponent exercise programs appear to be important in preventing loss of BMD and reduce the incidence of falls and consequently reduce fractures.
Certain lifestyle factors, including nutrition, smoking, and alcohol consumption, are known to play an important role in bone health. In terms of nutrition, accumulating evidence suggests that vegetable and fruit are potentially an efficacious intervention for preventing and reversing bone mass and structural loss in postmenopausal women. According to a recent meta-analysis, increased intake of vegetables, but not fruits, was found to be associated with a lower risk of hip fracture.[52] Several biological mechanisms have been proposed to explain this relation, most of them concerned with the possibility of the role of potassium, magnesium, calcium, vitamin K, and antioxidant (e.g., vitamin C, carotene, and carotenoids) content in fruits and vegetables in maintaining bone health; these elements can increase osteoclastogenesis and osteoclastic differentiation or inhibit osteoblastic differentiation.[53],[54],[55]
Alcohol consumption is considered a critical modifiable factor that affects bone health. Available evidence from a systemic review found a lower risk of hip fracture among persons consuming up to 0.5 to 1 drinks per day, and persons consuming more than 2 drinks per day had a higher risk of hip fracture.[56] Another study found that women consuming 1.8 drinks or more per day had a higher risk of wrist fracture compared with abstainers.[57] The link between vertebral osteoporotic fractures and alcohol has been reported in one study; the investigators found increased odds of fracture among men who consumed more than 0.3 drinks per day compared with abstainers [adjusted OR 4.61 (1.19–17.90)].[58]
In several meta-analyses, smoking has been recognized as a risk factor for low BMD and increased risk of fracture.[59],[60],[61],[62] It is hard to determine whether a decrease in bone density and increased risk of fracture are due to smoking itself or to other risk factors common among smokers. However, several biological effects of smoking on bone have been suggested. For example, smoking decreased intestinal calcium absorption and increased metabolism or decreased production of oestrogen, which may be affect indirectly on bone strength.[63] Furthermore, smoking may contribute to impaired physical balance and to increased risk of falling. However, a healthier lifestyle advocated reducing the risk of fractures.
Home hazards
Environmental hazards potentially include poor stairway design and disrepair, inadequate lighting, clutter, slippery floors, unsecured mats and rugs, and unstable furniture and obstructed walkways, among many others. In one-half to two-thirds of falls, the environment factors are considered the major risk factor.[64] Many older people attribute their falls to trips or slips inside the home or immediate home surroundings.[65] Unsecured mats and rugs, and unstable furniture are among the home hazard most frequently mentioned in the literature as unsafe and potentially increasing fall risk.[66] Numerous studies have found that floor mats in hallways, bathmats, loose rugs/mats, and flooring were among the most common home hazard associated with falls resulting in hip fractures.[66],[67] However, the existence of home hazards alone is insufficient to cause falls, and the interaction between a history of falls mobility limitations, and their home hazards appears to be more important.[68] Patients and their families should be advised to eliminate home hazards such as loose or frayed rugs and unstable furniture. Furthermore, adequate lighting, bathroom grab rails, raised toilet seat, secure stairway banisters, raising or lowering bed, and an easily accessible alarm system needed to be considered particularly in older person with prevous history of fall or functional disabilities.
Patients' education
Falls prevention education has been demonstrated to have beneficial effects on the lower fall risk and fall incidence rates. A recent randomized trial of elderly patients on hospital rehabilitation wards found that patients' education program consists of multimedia information (DVD and workbook) about falls and falls prevention, and tailored follow-up by a trained health professional significantly reduced falls and injurious falls.[69],[70] The intervention reduced falls on hospital rehabilitation wards by 40% and injury resulting from falls by 35%.[68] Feedback from 473 patients who received the education identified that patients found the education enjoyable and stated that the education helps raise their awareness, knowledge, and confidence to actively engage in falls prevention strategies.[71] Therefore, falls prevention education can be recommended to elderly pateints. However, future research may need to be done to explore the cost-effectiveness of patient education for the prevention of falls.
Prevention of fractures in elderly consists of therapy and prevention of osteoporosis, fall prevention, and using injury-site protection by high-risk elderly patients; concerning therapy and prevention of osteoporosis, maximizing peak bone mass, preventing bone loss by regular exercise, in particular weight-bearing and resistance exercise, calcium, and vitamin D, and use of evidence-based anti-osteoporotic drugs to treatment of established osteoporosis. For fall prevention, regular strength and balance training, reducing psychotropic medication, smoking cessation, avoiding excessive alcohol intake, and increased intake of vegetables. Hip protectors need to be considered for those at high risk of hip fracture and to reduce recurrent fracture. Special consideration can be taken to reduce home hazard, and falls prevention education can be recommended to the elderly with history of fall or mobility limitations.
Abreu HC, Reiners AA, Azevedo RC, Silva AM, Abreu D, Oliveira A. Incidence and predicting factors of falls of older inpatients. Rev Saude Publica 2015;49:37.
Ungar A, Rafanelli M, Iacomelli I, Brunetti MA, Ceccofiglio A, Tesi F, et al. Fall prevention in the elderly. Clin Cases Miner Bone Metab 2013;10:91-5.
Johnell O, Kanis JA. An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. Osteoporos Int 2006;17:1726-33.
Coughlan T, Dockery F. Osteoporosis and fracture risk in older people. Clin Med (Lond) 2014;14:187-91.
Ensrud KE. Epidemiology of fracture risk with advancingage. J Gerontol A Biol Sci Med Sci 2013;68:1236-42.
Svedbom A, Hernlund E, Ivergård M, Compston J, Cooper C, Stenmark J, et al.; EU Review Panel of IOF. Osteoporosis in the European Union: A compendium of country-specific reports. Arch Osteoporos 2013;8:137.
Wang J, Wang X, Fang Z, Lu N, Han L. The effect of FRAX on the prediction of osteoporotic fractures in urban middle-aged and elderly healthy Chinese adults. Clinics (Sao Paulo) 2017;72:289-93.
McCloskey EV, Odén A, Harvey NC, Leslie WD, Hans D, Johansson H, et al. A Meta-analysis of trabecular bone score in fracture risk prediction and its relationship to FRAX. J Bone Miner Res. 2016;31:940-8.
Shevroja E, Lamy O, Kohlmeier L, Koromani F, Rivadeneira F, Hans D. Use of trabecular bone score (TBS) as a complementary approach to dual-energy X-ray absorptiometry (DXA) for fracture risk assessment in clinical practice. J Clin Densitom 2017;20:334-45.
Coutinho ES, Fletcher A, Bloch KV, Rodrigues LC. Risk factors for falls with severe fracture in elderly people living in a middle-income country: A case control study. BMC Geriatr 2008;8:21.
Unnanuntana A, Gladnick BP, Donnelly E, Lane JM. The assessment of fracture risk. J Bone Joint Surg Am 2010;92:743-53.
Candel Romero C, Forner Cordero Á, Sánchez Santos JC, Pereiró Berenguer I. Relationship between vitamin D, osteoporotic fracture and falls. Med Clin (Barc) 2017;pii: S0025-7753:30345-7.
de Jong MR, Van der Elst M, Hartholt KA. Drug-related falls in older patients: Implicated drugs, consequences, and possible prevention strategies. Ther Adv Drug Saf 2013;4:147-54.
Campbell AJ, Robertson MC, Gardner MM, Norton RN, Buchner DM. Psychotropic medication withdrawal and a home-based exercise program to prevent falls: A randomized, controlled trial. J Am Geriatr Soc 1999;47:850-3.
Avenell A, Mak JC, O'Connell D. Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men. Cochrane Database Syst Rev 2014;4:CD000227.
Avenell A, Mak JC, O'Connell D. Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men. Cochrane Database Syst Rev 2014:CD000227.
Tang BM, Eslick GD, Nowson C, Smith C, Bensoussan A. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: A meta-analysis. Lancet 2007;370:657-66.
Harvey NC, Biver E, Kaufman JM, Bauer J, Branco J, Brandi ML, et al. The role of calcium supplementation in healthy musculoskeletal ageing: An expert consensus meeting of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the International Foundation for Osteoporosis (IOF) Osteoporos Int 2017;28:447-62.
Anderson JJ, Kruszka B, Delaney JA, He K, Burke GL, Alonso A, et al. Calcium intake from diet and supplements and the risk of coronary artery calcification and its progression among older adults: 10-year follow-up of the multi-ethnic study of atherosclerosis (MESA). J Am Heart Assoc 2016;11:5.
Tankeu AT, Ndip Agbor V, Noubiap JJ. Calcium supplementation and cardiovascular risk: A rising concern. J Clin Hypertens (Greenwich) 2017;19:640-6.
Byun JH, Jang S, Lee S, Park S, Yoon HK, Yoon BH, et al. The efficacy of bisphosphonates for prevention of osteoporotic fracture: An update meta-analysis. J Bone Metab 2017;24:37-49.
Zhou J, Wang T, Zhao X, Miller DR, Zhai S. Comparative efficacy of bisphosphonates to prevent fracture in men with osteoporosis: A systematic review with network meta-analyses. Rheumatol Ther 2016;3:117-28.
Wells GA, Cranney A, Peterson J, Boucher M, Shea B, Robinson V, et al. Alendronate for theprimary and secondaryprevention of osteoporotic fractures in postmenopausal women. Cochrane Database Syst Rev 2008:CD001155.
Wells GA, Cranney A, Peterson J, Boucher M, Shea B, Robinson V, et al. Alendronate for the primary and secondary prevention of osteoporotic fractures in postmenopausal women. Cochrane Database Syst Rev 2008:CD001155.
Binkley N, Bolognese M, Sidorowicz-Bialynicka A, Vally T, Trout R, Miller C, et al. Oral Calcitonin in Postmenopausal Osteoporosis (ORACAL) Investigators. A phase 3 trial of the efficacy and safety of oral recombinant calcitonin: The Oral Calcitonin in Postmenopausal Osteoporosis (ORACAL) trial. J Bone Miner Res 2012;27:1821-9.
Chesnut CH, Silverman S, Andriano K, Genant H, Gimona A, Harris S, et al. A randomized trial of nasal spray salmon calcitonin in postmenopausal women with established osteoporosis: The prevent recurrence of osteoporotic fractures study. PROOF Study Group. Am J Med. 2000;109:267-76.
Wells G, Chernoff J, Gilligan JP, Krause DS. Does salmon calcitonin cause cancer? A review and meta-analysis. Osteoporos Int 2016;27:13-9.
Nishikawa A, Ishida T, Taketsuna M, Yoshiki F, Enomoto H. Safety and effectiveness of daily teriparatide in a prospective observational study in patients with osteoporosis at high risk of fracture in Japan: Final report. Clin Interv Aging 2016;11:913-25.
Colón-Emeric CS, Saag KG. Osteoporotic fractures in older adults. Best Pract Res Clin Rheumatol 2006;20:695-706.
Torgerson DJ, Bell-Syer SE. Hormone replacement therapy and prevention of non-vertebral fractures: A meta-analysis of randomized trials. JAMA 2001;285:2891-7.
Torgerson DJ, Bell-Syer SE. Hormone replacement therapy and prevention of vertebral fractures: A meta-analysis of randomized trials. BMC Musculoskelet Disord 2001;2:7.
Gallagher JC. Estrogen treatment does not reduce fractures? Menopause 2014;21:111-2.
Fujiwara S, Hamaya E, Sato M, Graham-Clarke P, Flynn JA, Burge R. Systematic review of raloxifene in postmenopausal Japanese women with osteoporosis or low bone mass (osteopenia). Clin Interv Aging 2014;9:1879-93.
Cummings SR, Ensrud K, Delmas PD, LaCroix AZ, Vukicevic S, Reid DM, et al. Lasofoxifene in postmenopausal women with osteoporosis. N Engl J Med 2010;362:686-96.
Palacios S, Silverman SL, de Villiers TJ, Levine AB, Goemaere S, Brown JP, et al. Bazedoxifene Study Group. A 7-year randomized, placebo-controlled trial assessing the long-term efficacy and safety of bazedoxifene in postmenopausal women with osteoporosis: Effects on bone density and fracture. Menopause 2015;22:806-13.
Cummings SR, San Martin J, McClung MR, Siris ES, Eastell R, Reid IR, et al. Denosumab for prevention of fractures in postmenopausal women with osteoporosis. N Engl J Med 2009;361:756-65.
Nyman SR, Ballinger C, Phillips JE, Newton R. Characteristics of outdoor falls among older people: A qualitative study. BMC Geriatr 2013;13:125.
Santesso N, Carrasco-Labra A, Brignardello-Petersen R. Hip protectors for preventing hip fractures in older people. Cochrane Database Syst Rev 2014:CD001255.
Wolff I, van Croonenborg JJ, Kemper HC, Kostense PJ, Twisk JW. The effect of exercise training programs on bone mass: A meta-analysis of published controlled trials in pre- and postmenopausal women. Osteoporos Int 1999;9:1-12.
Kumar A, Delbaere K, Zijlstra GA, Carpenter H, Iliffe S, Masud T, et al. Exercise for reducing fear of falling in older people living in the community: Cochrane systematic review and meta-analysis. Age Ageing 2016;45:345-52.
de Labra C, Guimaraes-Pinheiro C, Maseda A, Lorenzo T, Millán-Calenti JC. Effects of physical exercise interventions in frail older adults: A systematic review of randomized controlled trials. BMC Geriatr 2015;15:154 [Review].
Warburton DE, Nicol CW, Bredin SS. Health benefits of physical activity: The evidence. CMAJ 2006;174:801-9.
Kujala UM, Kaprio J, Kannus P, Sarna S, Koskenvuo M. Physical activity and osteoporotic hip fracture risk in men. Arch Intern Med 2000;160:705-8.
Cadore EL, Rodríguez-Mañas L, Sinclair A, Izquierdo M. Effects of different exercise interventions on risk of falls, gait ability, and balance in physically frail older adults: A systematic review. Rejuvenation Res 2013;16:105-14
Bauman A, Merom D, Bull FC, Buchner DM, Fiatarone Singh MA. Updating the Evidence for physical activity: summative reviews of the epidemiological evidence, prevalence, and interventions to promote "active aging." Gerontologist. 2016;56(Suppl. 2):S268-80.
Cadore EL, Rodríguez-Mañas L, Sinclair A, Izquierdo M. Effects of different exercise interventions on risk of falls, gait ability, and balance in physically frail older adults: A systematic review. Rejuvenation Res 2013;16:105-14.
Fiatarone MA, O'Neill EF, Ryan ND, Clements KM, Solares GR, Nelson ME, et al. Exercise training and nutritional supplementation for physical frailty in very elderly people. N Engl J Med 1994;330:1769-75.
Lustosa LP, Silva JP, Coelho FM, Pereira DS, Parentoni AN, Pereira LS. Impact of resistance exercise program on functional capacity and muscular strength of knee extensor in pre-frail community-dwelling older women: A randomized crossover trial. Rev Bras Fisioter 2011;15:318-24.
Taylor D, Hale L, Schluter P, Waters DL, Binns EE, McCracken H, et al. Effectiveness of Tai Chi as a community-based falls prevention intervention: A randomized controlled trial. J Am Geriatr Soc 2012;60:841-8.
Liu H, Frank A. Tai chi as a balance improvement exercise for older adults: A systematic review. J Geriatr Phys Ther 2010;33:103-9
Luo SY, Li Y, Luo H, Yin Xh, Lin du R, Zhao K, et al. Increased intake of vegetables, but not fruits, may be associated with reduced risk of hip fracture: A meta-analysis. Sci Rep. 2016 Jan 25;6:19783. The practice (implementation)
Jehle S, Hulter HN, Krapf R. Effect of potassium citrate on bone density, microarchitecture, and fracture risk in healthy older adults without osteoporosis: A randomized controlled trial. J Clin Endocrinol Metab 2013;98:207-17.
Iwamoto J, Sato Y, Takeda T, Matsumoto H. High-dose vitamin K supplementation reduces fracture incidence in postmenopausal women: A review of the literature. Nutr Res 2009;29:221-8.
Aruoma OI, Grootveld M, Bahorun T. Free radicals in biology and medicine: From inflammation to biotechnology. Biofactors 2006;27:1-3.
Berg KM, Kunins HV, Jackson JL, Nahvi S, Chaudhry A, Harris KA Jr, et al. Association between alcohol consumption and both osteoporotic fracture and bone density. Am J Med 2008;121:406-18.
Hernandez-Avila M, Colditz GA, Stampfer MJ, Rosner B, Speizer FE, Willett WC. Caffeine, moderate alcohol intake, and risk of fractures of the hip and forearm in middle-aged women. Am J Clin Nutr 1991;54:157-63.
Samelson EJ, Hannan MT, Zhang Y, Genant HK, Felson DT, Kiel DP. Incidence and risk factors for vertebral fracture in women and men: 25-year follow-up results from the populations-based Framingham study. J Bone Miner Res 2006;21:1207-14.
Wu ZJ, Zhao P, Liu B, Yuan ZC. Effect of cigarette smoking on risk of hip fracture in men: A meta-analysis of 14 prospective cohort studies. PLoS One 2016;30:11.
Shen GS, Li Y, Zhao G, Zhou HB, Xie ZG, Xu W, et al. Cigarette smoking and risk of hip fracture in women: A meta-analysis of prospective cohort studies. Injury 2015;46:1333-40.
Kanis JA, Johnell O, Oden A, Johansson H, De Laet C, Eisman JA, et al. Smoking and fracture risk: A meta-analysis. Osteoporos Int 2005;16:155-62.
Vestergaard P, Mosekilde L. Fracture risk associated with smoking: A meta-analysis. J Intern Med 2003;254:572-83.
Høidrup S, Prescott E, Sørensen TI, Gottschau A, Lauritzen JB, Schroll M, et al. Tobacco smoking and risk of hip fracture in men and women. Int J Epidemiol 2000;29:253-9.
Stubbs D, Haslam R. Understanding and Preventing Falls. Taylor & Francis; 2005, p. 90-1.
Lord SR, Menz HB, Sherrington C. Home environment risk factors for falls in older people and the efficacy of home modifications. Age Ageing 2006;35(Suppl. 2):ii55-9.
Rosen T, Mack KA, Noonan RK. Slipping and tripping: Fall injuries in adults associated with rugs and carpets. J Inj Violence Res 2013;5:61-9.
Huang TT. Home environmental hazards among community-dwelling elderly persons in Taiwan. J Nurs Res 2005;13:49-57.
Gill TM, Williams CS, Tinetti ME. Environmental hazards and the risk of nonsyncopal falls in the homes of community-living older persons. Med Care 2000;38:1174-83.
Hill AM, McPhail SM, Waldron N, Etherton-Beer C, Ingram K, Flicker L, et al. Fall rates in hospital rehabilitation units after individualised patient and staff education programmes: A pragmatic, stepped-wedge, cluster-randomised controlled trial. Lancet 2015;385:2592-9.
Hill AM, Waldron N, Etherton-Beer C, McPhail SM, Ingram K, Flicker L, et al. A stepped-wedge cluster randomised controlled trial for evaluating rates of falls among inpatients in aged care rehabilitation units receiving tailored multimedia education in addition to usual care: A trial protocol. BMJ Open 2014;4:e004195.
Hill AM, Francis-Coad J, Haines TP, Waldron N, Etherton-Beer C, Flicker L, et al. "My independent streak may get in the way": How older adults respond to falls prevention education in hospital. BMJ Open 2016;6:e012363.
1 The effectiveness and cost-effectiveness of an integrated osteoporosis care programme for postmenopausal women in Flanders: study protocol of a quasi-experimental controlled design
Caroline Verdonck,Lieven Annemans,Stefan Goemaere,Bruno Lapauw,Geert Goderis,Elie Balligand,Marie-Paule Doom,Stany Perkisas,Liesbeth Borgermans
Archives of Osteoporosis. 2020; 15(1)
2 Reduced Recovery Capacity After Major Trauma in the Elderly: Results of a Prospective Multicenter Registry-Based Cohort Study
Viola Freigang,Karolina Müller,Antonio Ernstberger,Marlene Kaltenstadler,Lisa Bode,Christian Pfeifer,Volker Alt,Florian Baumann
Journal of Clinical Medicine. 2020; 9(8): 2356
3 Association of HIVEP3 Gene and Lnc RNA with Femoral Neck Bone Mineral Content and Hip Geometry by Genome-Wide Association Analysis in Chinese People
Weiwei Hu,Jinwei He,Luyue Qi,Chun Wang,Hua Yue,Jiemei Gu,Hao Zhang,Yi Wang,Zhenlin Zhang,Christian S. G bl
International Journal of Endocrinology. 2020; 2020: 1
4 Osteoporosediagnostik und -therapie bei über 65-Jährigen
Peter Dovjak
Zeitschrift für Gerontologie und Geriatrie. 2019;
Fares A
excercises
© International Journal of Preventive Medicine | Published by Wolters Kluwer - Medknow
Online since 2nd January, 2015


Despite slow registration, athletes came out in big numbers for the annual Whistler Kids of Steel Triathlon and adult Try-a-Tri on Saturday, May 23, no doubt encouraged by the best weather in years.
The Whistler Triathlon Club hosted the event, with sanctioning from Triathlon B.C., and the field included participants from throughout Sea to Sky, as well as Lillooet and Washington State.
The Kids of Steel race was first off the blocks.
In the girls 8 to 9 age group - 100 metre swim, 4 km bike and 1 km run - Jennifer Lafreniere placed first in 22:45, winning the run stage by a minute and a half. Sarah Fedder of Vancouver was second in 24:12, and Mila Wittenberg of Whistler was third in 25:28. Also from Whistler, Hailey Harkins and Aoife Gannon were sixth and seventh.
In 8 to 9 boys, Alec Coleman of West Vancouver was first in 21:37, followed closely by a trio of Whistler athletes - Michael Murdoch in 21:41, Fraser Doak in 22:11 and Sam Johnston in 22:26. Other Sea to Sky athletes were Troy Rozsypalek in fifth place, Adam Klimchuk-Brown sixth, Jack Forsyth eighth and Eric Smith ninth.
In the girls 10 to 11 age group - 100 metre swim, 4 km bike and 1 km run - Whistler's Gabby Smith was first in 23:31, followed by Makenna Bailey in 23:35. Shondra Martin of Squamish was third in 24:19. Other Sea to Sky finishers were Isobelle Williston in fourth, Nicole Deally in fifth and Steffi Denroche in sixth.
In the boys 10 to 11 age group Max Elliott of Whistler was first in 18 minutes and 34 seconds. Whistler's Nolan Welsh was slightly slower in the swim and on his bike, but had the fastest run time to place second in 19:00. Eli Chappell of Squamish was third in 19:19. Other local athletes were Finn Iles in fifth, Connor Toop in sixth, Gabriel Matteau Rushbrook in eighth, Zachary Davis in 10 th and Chase Velenosi in 12 th .
In 12 to 13 year old girls - 300 metre swim, 10 km bike and 3 km run - Grace Thompson of West Vancouver placed first overall in 46:44 with the best time in the swim and bike. Lauren Doak of Whistler was second in 50:23, placing second in the pool and on her bike and then first on the run. Keara Kimchuk-Brown of Squamish was third in 1:04:01, with Gabe Velenosi of Whistler trailing in fourth.
In 12 to 13 boys, Tyler Welsh of Whistler was first in 52:58, placing second on the swim and first biking and running. Rowan Doherty of West Vancouver was second in 44:36, and Whistler Taylor Derynck was third in 48:46.


text:
Technical note | 05 Oct 2022
Technical note: Common ambiguities in plant hydraulics
Technical note: Common ambiguities in plant hydraulics Technical note: Common ambiguities in plant hydraulics Yujie Wang and Christian Frankenberg
Yujie Wang1 and Christian Frankenberg1,2 Yujie Wang and Christian Frankenberg Yujie Wang1 and Christian Frankenberg1,2
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
Correspondence: Yujie Wang (wyujie@caltech.edu)
Received: 13 Apr 2022 – Discussion started: 25 Apr 2022 – Revised: 08 Sep 2022 – Accepted: 09 Sep 2022 – Published: 05 Oct 2022
Plant hydraulics gains increasing interest in plant ecophysiology and vegetation modeling. However, the hydraulic properties and profiles are often improperly represented, thus leading to biased results and simulations, e.g., the neglection of gravitational pressure drop results in overestimated water flux. We highlight the commonly seen ambiguities and/or misunderstandings in plant hydraulics, including (1) the distinction between water potential and pressure, (2) differences among hydraulic conductance and conductivity, (3) xylem vulnerability curve formulations, (4) model complexity, (5) stomatal-model representations, (6) bias from analytic estimations, (7) whole-plant vulnerability, and (8) neglected temperature dependencies. We recommend careful thinking before using or modifying existing definitions, methods, and models.
Wang, Y. and Frankenberg, C.: Technical note: Common ambiguities in plant hydraulics, Biogeosciences, 19, 4705–4714, https://doi.org/10.5194/bg-19-4705-2022, 2022.
Plant hydraulics gains increasing interest in understanding plants' responses and acclimation/adaptation to the environment (Santiago et al., 2004; McDowell et al., 2008; McDowell, 2011; Meinzer et al., 2010; Allen et al., 2010; Anderegg et al., 2012, 2016; Gleason et al., 2016; Wang et al., 2021a; Liu et al., 2021) and modeling canopy carbon and water fluxes within vegetation and land surface models (Buckley and Mott, 2013; Manzoni et al., 2013; McDowell et al., 2013; Sperry et al., 2017; Kennedy et al., 2019; Liu et al., 2020; Wang et al., 2020, 2021b; Sabot et al., 2022). However, xylem hydraulic properties and flow pressure profile are often improperly represented, due to the ambiguities and misunderstandings of various plant hydraulics parameters, though the plant hydraulics models used in topical research are already dramatically simplified compared to a complicated hydraulic architecture (Tyree and Ewers, 1991). For instance, distinctions between (a) water potential and pressure, (b) hydraulic conductance and conductivity, and (c) division and derivative are often not recognized. Further, the pursuit of simplicity, analytical solution, and novelty consequently results in modifications of known and well-tested functional forms. However, while researchers should be encouraged to try "new" approaches, it is important to keep in mind whether these changes or new methods (a) are correct and (b) need to be tested before moving forward. Any research violating the two principles would be unwarranted, no matter how "reasonable" they appear to be.
For example, regarding the modeling of plant hydraulics, since Wolf et al. (2016) and Sperry et al. (2017) advanced the stomatal optimization theory (Cowan and Farquhar, 1977) by quantifying hydraulic risk under a general gain–risk optimization framework, an increasing number of new models or variants have been developed (e.g., Anderegg et al., 2018; Dewar et al., 2018; Eller et al., 2018; Wang et al., 2020, 2021a; Chen et al., 2022), and many plant-hydraulics-based models show predictive skills comparable to statistical methods (Anderegg et al., 2018; Venturas et al., 2018; Eller et al., 2020; Wang et al., 2020; Sabot et al., 2022). Nevertheless, these tested models are not always replicated correctly, as researchers tend to mutate the formulations and sometimes hypotheses, such as the neglect of the rhizosphere component that plays an important role in drought stress conditions (Sperry et al., 1998; Sperry and Love, 2015; Sperry et al., 2016; Wang et al., 2020). Although the modifications often resemble tested models, they are often used without being thoroughly tested. Reasons behind the lack of model testing include the following: (a) there is not yet a well-established method or database to conveniently benchmark the new model variants; (b) research that focuses on varying the formulations and testing the variants is not encouraged by reviewers due to lack of novelty; and (c) one may not recognize the changes or differences that have been made. Here, we list some common ambiguities and misunderstandings in plant hydraulics and recommend careful thinking before using or modifying existing definitions, methods, and models.
2 Water potential and pressure
Water movement in xylem conduits includes mass flow through xylem conduits and diffusion between xylem conduits and capacitance tissues. Water mass flow (from site 1 to 2) in xylem is driven by the net force at the target plane per area (driving pressure, DP; see Table 1 for the list of symbols), which is DP=Px1-Px2+ρgh1-ρgh2 as in Fig. 1a. Dissolved ions only play a role in liquid water density but do not contribute to the driving pressure for long-distance transport in the xylem because the distance involved is too long for diffusion and thus chemical potential to be an important contributor. Water diffusion across the cell membrane (from xylem conduit to the cell) is driven by the potential difference, which is Px-Pc+Ψsx-Ψsc as in Fig. 1a, and the dissolved ions play a role through the osmotic potential.
Table 1List of symbols.
Figure 1Diagram for the difference between potential and pressure in plant hydraulics. (a) Difference among pressure difference (ΔP), potential difference (ΔΨ), and mass flow driving pressure (DP). Ψ is the sum of water pressure (Px for xylem and Pc for cell), osmotic potential (Ψsx for xylem and Ψsx for cell), and gravitational potential related to height (ρgh). (b) Example when ΔΨ differs from ΔP. In scenario 1 (left), where Ψsx2=Ψsx1 (labeled in blue), ΔΨ=DP. In scenario 2 (right), where Ψsx2<Ψsx1 (labeled in red), ΔΨ>DP. See Table 1 for the list of symbols.
As ion concentration in xylem conduit is very low, the osmotic potential in xylem conduit (Ψsx) is often ignored. Therefore, water potential is imperceptibly used in place of mass flow driving pressure (i.e., DP) because of the gravity term in it. To date, many people have used water potential rather than water pressure when modeling and describing mass water flow. This, though it may be easier for people to understand in most scenarios, is not correct. For example, in Fig. 1b, if the osmotic potential at the bottom and top are the same, the driving pressure and water potential difference are the same. However, if the osmotic potential at the top is more negative than at the bottom (for example, via adding a very thin layer of high-concentration salt solution), the driving pressure will be lower than the water potential difference. Besides the fact that the values of DP and water potential difference are not always equal, the primary reason for not misusing them is that water potential describes the tendency for water to move between adjacent phases (where water molecules will diffuse), whereas pressure is more relevant to bulk water movement. Thus, using potential difference for water mass flow is technically incorrect, and it is necessary to clarify the terminology to distinguish them.
Water potential and pressure used in plant hydraulics are both defined as a difference from a reference value: water potential (often denoted as Ψ or ψ in literature) is typically defined as the difference from the potential of pure water in the soil, and water pressure (often denoted as P or p) is typically defined as the difference from the environmental air pressure. Water pressure difference between xylem water and surrounding air is responsible for air-seeded conduit cavitation (Sperry and Tyree, 1988; Tyree and Sperry, 1989), which occurs when the pressure difference exceeds the capillary pressure at the air–water interface. Thus, using water potential to describe the xylem vulnerability curve should be avoided. Although the Δ values of the two are interchangeable in many scenarios (e.g., when there is no height change or external air pressure and osmotic potential in the xylem is zero), one needs to be cautious to avoid ambiguity by
using pressure in xylem cavitation,
using pressure in water mass flow,
using potential in water diffusion across the cell membrane (e.g., water exchange between xylem and living cell).
We note that water transport in plants also includes mass flow within the apoplastic spaces (e.g., in roots and leaves; Aloni et al., 1998) and through plasmodesmata (e.g., between bundle sheath and phloem; Schulz, 2015), liquid water diffusion among living cells, and gaseous vapor phase diffusion among water–air interfaces (e.g., vapor diffusion within the stomatal chamber; Buckley, 2015; Buckley et al., 2017). As recommended, it is more accurate to use potential for diffusion and pressure for mass flow.
A commonly seen mistake is the use of leaf water potential to describe measurements from the pressure chamber method (Scholander et al., 1964; Boyer, 1967), which gives a decent estimate of xylem water pressure. People often refer to the measurement as leaf water potential, as (a) xylem conduit water has very low solute content; (b) the gravity term is often negligible compared to the very negative leaf xylem water pressure; and (c) if the water has reached equilibrium internally prior to the pressure chamber measurement, xylem water potential should equal that in the mesophyll. However, it is always more accurate to treat it as an equivalent pressure or a balance pressure (at the end of xylem). Similar logic applies to xylem water potential and xylem water pressure and so does the thermocouple psychrometer method (Boyer and Knipling, 1965; Boyer, 1968). It is recommended to refer to the measurement as leaf or xylem water pressure or balance pressure in the future, rather than leaf or xylem water potential that is not directly measurable.
3 Hydraulic conductance and conductivity
Hydraulic conductance (k) and conductivity (K) are also often confused in the literature (e.g., Kannenberg et al., 2019; Cardoso et al., 2020; Li et al., 2021). Hydraulic conductance (flow rate divided by driving pressure) is an extensive property (depends on the extent/size of the system), whereas hydraulic conductivity is an intensive property that is supposed to represent different xylem anatomy. The most widely used definitions for conductance and conductivity are the following: (a) hydraulic conductance (namely k) is the ratio between flow rate through the segment (Q) and driving pressure (ΔP−ρgΔh) (an extensive parameter depending on segment length and cross-section area); (b) hydraulic conductivity (namely K) is the ratio between flow rate and driving pressure gradient (an extensive parameter depending on segment cross-section area); (c) sapwood-area-specific hydraulic conductivity (KS) is the ratio between hydraulic conductivity and xylem sapwood area (AS); and (d) leaf-area-specific hydraulic conductivity (KL) is the ratio between hydraulic conductivity and leaf area the xylem supports (AL):
(1)k=QΔP-ρgΔh,(2)K=k⋅L,
(3)KS=KAS,(4)KL=KAL.
Note that only KS and KL are per unit conducting area and thus can be treated as "intrinsic" properties for comparison purposes: KS for sapwood water permeability and KL for leaf water supply capability. However, KL may not best describe leaf water supply capability. For example, if two branches have the same KS, leaf area, and sapwood area but differ in their length, the computed K and KL would be the same for the two branches even though the actual leaf water supply capabilities differ. In comparison, conductance of the entire branch divided by leaf area of the branch, i.e., leaf-area-specific hydraulic conductance (kL) as inspired by leaf-area-specific whole-plant hydraulic conductance, would be a better measure for leaf water supply. kL can be estimated using
(5) k L = k branch A L ,
where kbranch is hydraulic conductance of the entire branch (not a stem segment).
4 Xylem vulnerability curve (VC)
Various formulas have been used to represent xylem VC, and the three most common ones are the Weibull cumulative probability function (Eq. 6) (e.g., Sperry et al., 2016; Love et al., 2019), logistic function (Eq. 7) (e.g., Feng et al., 2018; Huber et al., 2019), and power function (Eq. 8) (e.g., Eller et al., 2018; Liu et al., 2020):
(6)kkmax=exp--PBC=2-PP50C,(7)kkmax=1-11+a⋅expb⋅P=1-11+expb⋅P-P50,(8)kkmax=11+m⋅-Pn=11+PP50n,
where B, C, a, b, m, and n are vulnerability function parameters and P50 is the water pressure at which the tissue loses 50 % of its conductance. Note that there are also more complex VC formulations based on the three, such as the double Weibull function used in hydraulic fiber bridge (Cai et al., 2014; Pan and Tyree, 2019) and cavitation fatigue (Feng et al., 2015; Zhang et al., 2018).
We should be aware that the logistic VC function (Eq. 7 or a formulation based on it) does not always start from 1 when P=0. This problem is minor for sigmoidal VCs (s-shaped); however, the offset at P=0 could introduce bias if the VC becomes more exponential (r-shaped; see Fig. 5 of Huber et al., 2019, for an example). In this case, fitting VC using Eq. (7) would result in overestimated kmax and less negative P50. Thus, Eq. (7) should be rescaled to minimize the bias, and the modified formulation is
(9)kkmax=a⋅expb⋅P1+a⋅expb⋅P⋅1+aa=(1+a)⋅expb⋅P1+a⋅expb⋅P,(10)P50=-log2+ab.
5 Hydraulic-model complexity
Plant hydraulics models have various complexities depending on the various aims of research and difficulties in model parameterization (Tyree and Ewers, 1991; Tyree and Zimmermann, 2002). In terms of flow profiles, the models can be categorized to steady-state and non-steady-state models. The steady-state models use a constant flow rate within roots, stem, and leaves. The non-steady-state models employ a changing flow rate within or among different tissues given the water exchange between xylem and capacitance tissues. In terms of the model complexity, the models range from a single element to a xylem network (say multiple roots and multiple canopy layers). Further, hydraulic conductance of an element may change with the growth of plants; for example, the drought legacy, maximum hydraulic conductance, and VC vary with the stack of new tree rings (McCulloh and Sperry, 2005; Cai and Tyree, 2010). Although more complex models may better represent the water flow and pressure profiles within the plants, increasing difficulties in model parameterization makes these more complex models less appealing to users. However, inappropriate model selection could result in biased results, for instance, modeling plant hydraulics at a steady state for plants with high water capacity and ignoring a vessel-tapering effect when modeling xylem growth. Thus, it is important to select plant hydraulics models with adequate complexity in topical research. See the section below for a detailed example of how reduced model complexity (ignoring VC segmentation) may bias the modeled hydraulic risk and thus stomatal responses.
6 Stomatal-model representation
Plant-hydraulics-based stomatal models are gaining increasing interest in the vegetation and land modeling communities (e.g., Kennedy et al., 2019; Sabot et al., 2020) as they predict stomatal closure at dry environmental conditions without employing an arbitrary tuning factor (often known as the β factor) (Powell et al., 2013). For instance, the recently developed optimality-theory-based models propose that plants should balance the gain and risk associated with stomatal functioning (Wolf et al., 2016; Sperry et al., 2017). When plants open their stomata more, plants gain more photosynthetic carbon but lose more water and have higher risk in hydraulic failure; therefore, plants are supposed to find a sweet spot to maximize the difference between the gain and risk. These optimality theory models, particularly those weighing the risk based on plant hydraulics, show comparable or better predictive skills compared to the statistical approaches (Anderegg et al., 2018; Eller et al., 2018; Venturas et al., 2018; Wang et al., 2020; Sabot et al., 2022). However, a common mistake when using plant-hydraulics-based models is that one does not follow the original model formula or hypothesis. For example, the Sperry et al. (2017) model defines the risk associated with stomatal functioning (Θ) as
(11)Θ=Amax⋅kcanopy,ref-kcanopy(Pcanopy)kcanopy,ref-kcrit,(12)kcanopy=dEdPcanopy,
where Amax is the maximal achievable photosynthetic rate at the given setting, Pcanopy is the water pressure at the end of leaf xylem, kcanopy,ref is the maximum kcanopy when the transpiration rate is 0, kcrit is kcanopy when the transpiration rate reaches the maximum transport capacity of the xylem, and E is the transpiration rate. kcrit by definition is 0, as a minimum incremental transpiration rate results in infinity increase in xylem pressure (the dE/dPcanopy=0 in Fig. 2). Thus, in the subsequent research where Sperry et al. (2017) was tested (Venturas et al., 2018; Wang et al., 2020), the model has been reformulated to
(13) Θ = A max ⋅ 1 - k canopy ( P canopy ) k canopy,ref .
Note here that kcanopy is the derivative of a water supply curve at given soil water potential and canopy water pressure, and kcanopy/kcanopy,ref is different from the (a) relative conductance of root, stem, or leaf xylem (i.e., k/kref, where kref is the maximum k at a reference xylem pressure) and (b) relative whole-plant hydraulic conductance (kplant=E/DP). However, model descriptions from various sources may be contrasting: Sperry et al. (2017) expressed their risk in derivative form; Eller et al. (2018) expressed their risk calculations in three completely different ways including division (their Eq. 2.3), derivative (their Eq. 2.6), and point estimation (their Eq. 2.8); Mencuccini et al. (2019) interpreted the two models based on kplant; and Wang et al. (2020) interpreted the two models based on the derivative forms. See Fig. 2 for how the three quantities differ.
Figure 2Difference between quantities used in plant hydraulics. The simulation is done for a plant with soil water potential of −0.5 MPa, no gravity term, and no drought legacy effect from previous xylem embolism. See Table 1 for the list of symbols.
Figure 3Comparison of different risk measures of stomatal opening. (a)–(e) Values are relative to the maximum when soil water potential is 0 and the transpiration rate is 0. (f)–(j) Values are relative to the maximal when the transpiration rate is 0 at the given soil water potential. The simulation is done assuming there is no drought legacy effect from previous xylem embolism. For the simulation, the plant has a root : stem : leaf resistance ratio of 2 : 1 : 1; root and stem height change are 1 and 10 m, respectively; VCs are represented using a Weibull function; Weibull B and C are 1.879 MPa and 2.396 for root, 2.238 MPa and 9.380 for stem, and 1.897 MPa and 2.203 for leaf (data from Wang et al., 2019). See Table 1 for the list of symbols.
For a xylem that does not have height change or VC segmentation, dE/dPcanopy=k(P). Otherwise, using k(P) to proxy dE/dPcanopy could result in biases, particularly when gravity is not negligible and when tissue VCs differ dramatically (Sperry et al., 2016; McCulloh et al., 2019). Using the parameters of a real plant as an example (data from Wang et al., 2019), it is obvious that none of the root, stem, leaf, or whole-plant hydraulic conductance is a good dE/dPcanopy proxy (Fig. 3). Therefore, researchers should test the models that differ from the original forms. Note that the primary reason that Sperry et al. (2017) used dE/dPcanopy was to account for the VC segmentation. Using stem VC (easiest to measure; typically more resistant than roots and leaves) to proxy root and leaf VCs in stomatal models would likely result in less sensitive stomatal response to environmental stimuli such as soil moisture (Fig. 3).
7 Analytic solution and estimation
The pursuit of simplicity and analytic solution often leads to biased results, for example, using leaf or stem VC as a proxy for dE/dPcanopy (e.g., Fig. 3) and ignoring the impact of gravity (e.g., Fig. 4). As a result, it is important to distinguish true analytic solution from analytic estimation. For example in a xylem water supply curve, when gravitational pressure drop is neglected, flow rate at a given canopy water pressure will be overestimated (Fig. 4). The greater the height changes are, the more E is overestimated (Fig. 4). The absolute value of E overestimation decreases with more negative soil water potential, whereas the relative E overestimation increases with more negative soil water potential (Fig. 4). Thus, given the potentially great biases, it is recommended to verify any analytic or numerical estimations against a true numerical solution before using them in research.
Figure 4Water supply curve at different Ψsoil values for xylem with different height change. The simulation is done assuming there is no drought legacy effect from previous xylem embolism. See Table 1 for the list of symbols.
8 Whole-plant vulnerability "curve"
The ideas of whole-plant conductance and VC largely advance the understanding of how plant traits coordinate, as they provide a simple way to correlate different traits (see McCulloh et al., 2019, for an overview). Whole-plant hydraulic conductance (kplant) depends on not only the upstream water potential (namely Ψsoil) but also the downstream water pressure (Pcanopy): kplant=f(Ψsoil,Pcanopy)=EDP. However, one should be aware of the hidden assumptions when using the term whole-plant hydraulic conductance (or any similar terms): upstream water potential (soil water potential in this scenario) is the same everywhere, and driving pressure is the same everywhere, regardless of plant height, canopy light conditions, and the root–stem–leaf network. Therefore, in the practice of modeling or research, the two assumptions are barely met. Further, note that kplant is an extensive parameter from root to leaves, and xylem water pressure and xylem hydraulic conductance are profiles rather than being constant along the flow path. Therefore, by definition, there is not a whole-plant vulnerability curve; instead, f(Ψsoil,Pcanopy) is a whole-plant vulnerability surface (Fig. 5). It is obvious that neither Ψsoil, Pcanopy, nor a mean pressure can predict a unique kplant (although the change in kplant is relatively smaller for the mean pressure; dotted line in Fig. 5). Further, the drought legacy effect from previous non-refillable xylem embolism (Anderegg et al., 2015) would further complicate the scenario as the "surface" changes with drought legacy. Therefore, it is not recommended to use the term whole-plant vulnerability curve in research.
Figure 5Whole-plant vulnerability surface. Whole-plant hydraulic conductance is computed using kplant=EΨsoil-Pcanopy-ρgh. The dotted line plots the scenario when mean xylem water pressure is −1.6 MPa. The simulation is done assuming there is no drought legacy effect from previous xylem embolism. See Table 1 for the list of symbols.
9 Temperature effects
When modeling plant hydraulics, the temperature effects on viscosity (η), surface tension (γ), and osmotic potential are typically ignored. However, when water temperature decreases from 25 to 10 ∘C (298.15 to 283.15 K), (1) viscosity of water increases by 43.8 %, meaning a > 40 % increase in pressure drop along the flow path for a given flow rate; (2) surface tension of water increases by 3.1 %, meaning that the capillary force withholding the air–water interface at the pit membrane increases by 3.1 % for a given curvature radius (xylem becomes more resistant to cavitation) and that soil metric potential becomes 3.1 % more negative for a given soil water content; and (3) soil osmotic water potential would be 5.0 % less negative for a given ion concentration. Therefore, a more reasonable way to describe a xylem VC (e.g., using Weibull function) should be
(14) k = k max , 25 ⋅ η 25 η ⋅ exp - - P B 25 ⋅ γ 25 γ C 25 ,
where the subscript 25 denotes the values are at a reference temperature of 25 ∘C. In other words, kmax needs to be scaled to kmax,25⋅η25/η, and P needs to be scaled to P⋅γ25/γ.
10 Conclusions
Plant hydraulics is often improperly represented in research, potentially resulting in ambiguities to those who are not familiar with the terminologies. This paper documents differences among commonly seen ambiguous and miscellaneous terms that are often not recognized and the mistakes and misunderstandings researchers may make when using established methods and models. The mathematics and visualizations of the documented items will help researchers in their research and teaching associated with plant hydraulics.
Simulations of the results in Figs. 2–5 were done using a registered Julia package PlantHydraulics.jl (v0.2.13). Code used for the simulations can be found at CaltechDATA (https://doi.org/10.22002/g862k-ahh79, Wang, 2022).
No data sets were used in this article.
YW conceived the idea. YW and CF prepared the results and wrote the paper.
The contact author has declared that none of the authors has any competing interests.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
We gratefully acknowledge the generous support of Eric and Wendy Schmidt (by recommendation of the Schmidt Futures) and the Heising-Simons Foundation. We benefit from the discussion with Tom Buckley on the proper usages of water potential and water pressure.
This research has been supported by the National Aeronautics and Space Administration (Carbon Cycle Science, grant no. 80NSSC21K1712).
This paper was edited by Andreas Ibrom and reviewed by two anonymous referees.
Allen, C. D., Macalady, A. K., Chenchouni, H., Bachelet, D., McDowell, N., Vennetier, M., Kitzberger, T., Rigling, A., Breshears, D. D., Hogg, E. T., Gonzalez, P., Fensham, R., Zhang, Z., Castro, J., Demidova, N., Lim, J.-H., Allard, G., Running, S. W., Semerci, A., and Cobb, N.: A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests, Forest Ecol. Manage., 259, 660–684, 2010. a
Aloni, R., Enstone, D. E., and Peterson, C. A.: Indirect evidence for bulk water flow in root cortical cell walls of three dicotyledonous species, Planta, 207, 1–7, 1998. a
Anderegg, W. R. L., Berry, J. A., Smith, D. D., Sperry, J. S., Anderegg, L. D., and Field, C. B.: The roles of hydraulic and carbon stress in a widespread climate-induced forest die-off, P. Natl. Acad. Sci. USA, 109, 233–237, 2012. a
Anderegg, W. R. L., Schwalm, C., Biondi, F., Camarero, J. J., Koch, G., Litvak, M., Ogle, K., Shaw, J. D., Shevliakova, E., Williams, A., Wolf, A., Ziaco, E., and Pacala, S.: Pervasive drought legacies in forest ecosystems and their implications for carbon cycle models, Science, 349, 528–532, 2015. a
Anderegg, W. R. L., Klein, T., Bartlett, M., Sack, L., Pellegrini, A. F. A., Choat, B., and Jansen, S.: Meta-analysis reveals that hydraulic traits explain cross-species patterns of drought-induced tree mortality across the globe, P. Natl. Acad. Sci. USA, 113, 5024–5029, 2016. a
Anderegg, W. R. L., Wolf, A., Arango-Velez, A., Choat, B., Chmura, D. J., Jansen, S., Kolb, T., Li, S., Meinzer, F. C., Pita, P., Resco de Dios, V., Sperry, J. S., Wolfe, B. T., and Pacala, S.: Woody plants optimise stomatal behaviour relative to hydraulic risk, Ecol. Lett., 21, 968–977, 2018. a, b, c
Boyer, J. S.: Leaf water potentials measured with a pressure chamber, Plant Physiol., 42, 133–137, 1967. a
Boyer, J. S.: Relationship of water potential to growth of leaves, Plant Physiol., 43, 1056–1062, 1968. a
Boyer, J. S. and Knipling, E. B.: Isopiestic technique for measuring leaf water potentials with a thermocouple psychrometer, P. Natl. Acad. Sci. USA, 54, 1044–1051, 1965. a
Buckley, T. N.: The contributions of apoplastic, symplastic and gas phase pathways for water transport outside the bundle sheath in leaves, Plant Cell Environ., 38, 7–22, 2015. a
Buckley, T. N. and Mott, K. A.: Modelling stomatal conductance in response to environmental factors, Plant Cell Environ., 36, 1691–1699, 2013. a
Buckley, T. N., John, G. P., Scoffoni, C., and Sack, L.: The sites of evaporation within leaves, Plant Physiol., 173, 1763–1782, 2017. a
Cai, J. and Tyree, M. T.: The impact of vessel size on vulnerability curves: Data and models for within-species variability in saplings of aspen, Populus tremuloides Michx., Plant Cell Environ., 33, 1059–1069, 2010. a
Cai, J., Li, S., Zhang, H., Zhang, S., and Tyree, M. T.: Recalcitrant vulnerability curves: Methods of analysis and the concept of fibre bridges for enhanced cavitation resistance, Plant Cell Environ., 37, 35–44, 2014. a
Cardoso, A. A., Visel, D., Kane, C. N., Batz, T. A., García Sánchez, C., Kaack, L., Lamarque, L. J., Wagner, Y., King, A., Torres-Ruiz, J. M., Corso, D., Burlett, R., Badel, E., Cochard, H., Delzon, S., Jansen, S., and McAdam, S. A. M.: Drought-induced lacuna formation in the stem causes hydraulic conductance to decline before xylem embolism in Selaginella, New Phytol., 227, 1804–1817, 2020. a
Chen, C., Riley, W. J., Prentice, I. C., and Keenan, T. F.: CO2 fertilization of terrestrial photosynthesis inferred from site to global scales, P. Natl. Acad. Sci. USA, 119, e2115627119, https://doi.org/10.1073/pnas.2115627119, 2022. a
Cowan, I. R. and Farquhar, G. D.: Stomatal function in relation to leaf metabolism and environment, Sym. Soc. Exp. Biol., 31, 471–505, 1977. a
Dewar, R., Mauranen, A., Mäkelä, A., Hölttä, T., Medlyn, B., and Vesala, T.: New insights into the covariation of stomatal, mesophyll and hydraulic conductances from optimization models incorporating nonstomatal limitations to photosynthesis, New Phytol., 217, 571–585, 2018. a
Eller, C. B., Rowland, L., Oliveira, R. S., Bittencourt, P. R. L., Barros, F. V., da Costa, A. C. L., Meir, P., Friend, A. D., Mencuccini, M., Sitch, S., and Cox, P.: Modelling tropical forest responses to drought and El Niño with a stomatal optimization model based on xylem hydraulics, Philos. T. Roy. Soc. B, 373, 20170315, https://doi.org/10.1098/rstb.2017.0315, 2018. a, b, c, d
Eller, C. B., Rowland, L., Mencuccini, M., Rosas, T., Williams, K., Harper, A., Medlyn, B. E., Wagner, Y., Klein, T., Teodoro, G. S., Oliverira, R. S., Matos, I. S., Rosado, B. H. P., Fuchs, K., Wohlfahrt, G., Montagnani, L., Meir, P., Sitch, S., and Cox, P. M.: Stomatal optimization based on xylem hydraulics (SOX) improves land surface model simulation of vegetation responses to climate, New Phytol., 226, 1622–1637, 2020. a
Feng, F., Ding, F., and Tyree, M. T.: Investigations concerning cavitation and frost fatigue in clonal 84K poplar using high-resolution cavitron measurements, Plant Physiol., 168, 144–155, 2015. a
Feng, X., Ackerly, D. D., Dawson, T. E., Manzoni, S., Skelton, R. P., Vico, G., and Thompson, S. E.: The ecohydrological context of drought and classification of plant responses, Ecol. Lett., 21, 1723–1736, 2018. a
Gleason, S. M., Westoby, M., Jansen, S., Choat, B., Hacke, U. G., Pratt, R. B., Bhaskar, R., Brodribb, T. J., Bucci, S. J., Cao, K.-F., Cochard, H., Delzon, S., Domec, J.-C., Fan, Z.-X., Field, T. S., Jacobsen, A. L., Johnson, D. M., Lens, F., Maherali, H., Martinez-Vilalta, J., Mayr, S., McCulloh, K. A., Mencuccini, M., Mitchell, O. J., Morris, H., Nardini, A., Pittermann, J., Plavcova, L., Schreiber, S., Sperry, J. S., Wright, I. J., and Zanne, A. E.: Weak tradeoff between xylem safety and xylem-specific hydraulic efficiency across the world's woody plant species, New Phytol., 209, 123–136, 2016. a
Huber, A. E., Melcher, P. J., Piñeros, M. A., Setter, T. L., and Bauerle, T. L.: Signal coordination before, during and after stomatal closure in response to drought stress, New Phytol., 224, 675–688, 2019. a, b
Kannenberg, S. A., Novick, K. A., and Phillips, R. P.: Anisohydric behavior linked to persistent hydraulic damage and delayed drought recovery across seven North American tree species, New Phytol., 222, 1862–1872, 2019. a
Kennedy, D., Swenson, S., Oleson, K. W., Lawrence, D. M., Fisher, R., Lola da Costa, A. C., and Gentine, P.: Implementing plant hydraulics in the community land model, version 5, J. Adv. Model. Earth Syst., 11, 485–513, 2019. a, b
Li, S., Fang, L., Hegelund, J. N., and Liu, F.: Elevated CO2 modulates plant hydraulic conductance through regulation of PIPs under progressive soil drying in tomato plants, Front. Plant Sci., 12, 666066, https://doi.org/10.3389/fpls.2021.666066, 2021. a
Liu, H., Ye, Q., Gleason, S. M., He, P., and Yin, D.: Weak tradeoff between xylem hydraulic efficiency and safety: climatic seasonality matters, New Phytol., 229, 1440–1452, 2021. a
Liu, Y., Kumar, M., Katul, G. G., Feng, X., and Konings, A. G.: Plant hydraulics accentuates the effect of atmospheric moisture stress on transpiration, Nat. Clim. Change, 10, 691–695, 2020. a, b
Love, D. M., Venturas, M. D., Sperry, J. S., Brooks, P. D., Pettit, J. L., Wang, Y., Anderegg, W. R. L., Tai, X., and Mackay, D. S.: Dependence of aspen stands on a subsurface water subsidy: Implications for climate change impacts, Water Resour. Res., 55, 1833–1848, 2019. a
Manzoni, S., Vico, G., Palmroth, S., Porporato, A., and Katul, G.: Optimization of stomatal conductance for maximum carbon gain under dynamic soil moisture, Adv. Water Resour., 62, 90–105, 2013. a
McCulloh, K. A. and Sperry, J. S.: Patterns in hydraulic architecture and their implications for transport efficiency, Tree Physiol., 25, 257–267, 2005. a
McCulloh, K. A., Domec, J.-C., Johnson, D. M., Smith, D. D., and Meinzer, F. C.: A dynamic yet vulnerable pipeline: Integration and coordination of hydraulic traits across whole plants, Plant Cell Environ., 42, 2789–2807, 2019. a, b
McDowell, N., Pockman, W. T., Allen, C. D., Breshears, D. D., Cobb, N., Kolb, T., Plaut, J., Sperry, J., West, A., Williams, D. G., and Yepez, E. A.: Mechanisms of plant survival and mortality during drought: why do some plants survive while others succumb to drought?, New Phytol., 178, 719–739, 2008. a
McDowell, N. G.: Mechanisms linking drought, hydraulics, carbon metabolism, and vegetation mortality, Plant Physiol., 155, 1051–1059, 2011. a
McDowell, N. G., Fisher, R. A., Xu, C., Domec, J.-C., Hölttä, T., Mackay, D. S., Sperry, J. S., Boutz, A., Dickman, L., Gehres, N., Limousin, J. M., Macalady, A., Martinez-Vilalta, J., Mencuccini, M., Plaut, H. A., Ogee, J., Panglem, R. E., Rasse, D. P., Ryan, M. G., Sevanto, S., Waring, R. H., Williams, A. P., Yepez, E. A., and Pockman, W. T.: Evaluating theories of drought-induced vegetation mortality using a multimodel–experiment framework, New Phytol., 200, 304–321, 2013. a
Meinzer, F. C., McCulloh, K. A., Lachenbruch, B., Woodruff, D. R., and Johnson, D. M.: The blind men and the elephant: the impact of context and scale in evaluating conflicts between plant hydraulic safety and efficiency, Oecologia, 164, 287–296, 2010. a
Mencuccini, M., Manzoni, S., and Christoffersen, B.: Modelling water fluxes in plants: From tissues to biosphere, New Phytol., 222, 1207–1222, 2019. a
Pan, R. and Tyree, M. T.: How does water flow from vessel to vessel? Further investigation of the tracheid bridge concept, Tree Physiol., 39, 1019–1031, 2019. a
Powell, T. L., Galbraith, D. R., Christoffersen, B. O., Harper, A., Imbuzeiro, H., Rowland, L., Almeida, S., Brando, P. M., Costa, A. C. L., Costa, M. H., and Moorcroft, P. R.: Confronting model predictions of carbon fluxes with measurements of Amazon forests subjected to experimental drought, New Phytol., 200, 350–365, 2013. a
Sabot, M. E., De Kauwe, M. G., Pitman, A. J., Medlyn, B. E., Verhoef, A., Ukkola, A. M., and Abramowitz, G.: Plant profit maximization improves predictions of European forest responses to drought, New Phytol., 226, 1638–1655, 2020. a
Sabot, M. E., De Kauwe, M. G., Pitman, A. J., Medlyn, B. E., Ellsworth, D. S., Martin-StPaul, N., Wu, J., Choat, B., Limousin, J.-M., Mitchell, P. J., Rogers, A., and Serbin, S. P.: One Stomatal Model to Rule Them All? Towards Improved Representation of Carbon and Water Exchange in Global Models, J. Adv. Model. Earth Syst., 14, e2021MS002761, https://doi.org/10.1029/2021MS002761, 2022. a, b, c
Santiago, L. S., Goldstein, G., Meinzer, F. C., Fisher, J. B., Machado, K., Woodruff, D., and Jones, T.: Leaf photosynthetic traits scale with hydraulic conductivity and wood density in Panamanian forest canopy trees, Oecologia, 140, 543–550, 2004. a
Scholander, P. F., Hammel, H., Hemmingsen, E., and Bradstreet, E.: Hydrostatic pressure and osmotic potential in leaves of mangroves and some other plants, P. Natl. Acad. Sci. USA, 52, 119–125, 1964. a
Schulz, A.: Diffusion or bulk flow: how plasmodesmata facilitate pre-phloem transport of assimilates, J. Plant Res., 128, 49–61, 2015. a
Sperry, J. S. and Love, D. M.: What plant hydraulics can tell us about responses to climate-change droughts, New Phytol., 207, 14–27, 2015. a
Sperry, J. S. and Tyree, M. T.: Mechanism of water stress-induced xylem embolism, Plant Physiol., 88, 581–587, 1988. a
Sperry, J. S., Adler, F. R., Campbell, G. S., and Comstock, J. P.: Limitation of plant water use by rhizosphere and xylem conductance: Results from a model, Plant Cell Environ., 21, 347–359, 1998. a
Sperry, J. S., Wang, Y., Wolfe, B. T., Mackay, D. S., Anderegg, W. R. L., McDowell, N. G., and Pockman, W. T.: Pragmatic hydraulic theory predicts stomatal responses to climatic water deficits, New Phytol., 212, 577–589, 2016. a, b, c
Sperry, J. S., Venturas, M. D., Anderegg, W. R. L., Mencuccini, M., Mackay, D. S., Wang, Y., and Love, D. M.: Predicting stomatal responses to the environment from the optimization of photosynthetic gain and hydraulic cost, Plant Cell Environ., 40, 816–830, 2017. a, b, c, d, e, f, g
Tyree, M. T. and Ewers, F. W.: The hydraulic architecture of trees and other woody plants, New Phytol., 119, 345–360, 1991. a, b
Tyree, M. T. and Sperry, J. S.: Vulnerability of xylem to cavitation and embolism, Annu. Rev. Plant Biol., 40, 19–36, 1989. a
Tyree, M. T. and Zimmermann, M. H.: Xylem structure and the ascent of sap, 2nd edn., Springer Berlin, Heidelberg, https://doi.org/10.1007/978-3-662-04931-0, 2002. a
Venturas, M. D., Sperry, J. S., Love, D. M., Frehner, E. H., Allred, M. G., Wang, Y., and Anderegg, W. R. L.: A stomatal control model based on optimization of carbon gain versus hydraulic risk predicts aspen sapling responses to drought, New Phytol., 220, 836–850, 2018. a, b, c
Wang, Y.: Code for research papers (Version 1), CaltechDATA [data set], https://doi.org/10.22002/g862k-ahh79, 2022. a
Wang, Y., Sperry, J. S., Venturas, M. D., Trugman, A. T., Love, D. M., and Anderegg, W. R. L.: The stomatal response to rising CO2 concentration and drought is predicted by a hydraulic trait-based optimization model, Tree Physiol., 39, 1416–1427, 2019. a, b
Wang, Y., Sperry, J. S., Anderegg, W. R. L., Venturas, M. D., and Trugman, A. T.: A theoretical and empirical assessment of stomatal optimization modeling, New Phytol., 227, 311–325, 2020. a, b, c, d, e, f, g
Wang, Y., Anderegg, W. R., Venturas, M. D., Trugman, A. T., Yu, K., and Frankenberg, C.: Optimization theory explains nighttime stomatal responses, New Phytol., 230, 1550–1561, 2021a. a, b
Wang, Y., Köhler, P., He, L., Doughty, R., Braghiere, R. K., Wood, J. D., and Frankenberg, C.: Testing stomatal models at the stand level in deciduous angiosperm and evergreen gymnosperm forests using CliMA Land (v0.1), Geosci. Model Dev., 14, 6741–6763, https://doi.org/10.5194/gmd-14-6741-2021, 2021b. a
Wolf, A., Anderegg, W. R. L., and Pacala, S. W.: Optimal stomatal behavior with competition for water and risk of hydraulic impairment, P. Natl. Acad. Sci. USA, 113, E7222–E7230, 2016. a, b
Zhang, W., Feng, F., and Tyree, M. T.: Seasonality of cavitation and frost fatigue in Acer mono Maxim., Plant Cell Environ., 41, 1278–1286, 2018. a
Water potential and pressure
Hydraulic conductance and conductivity
Xylem vulnerability curve (VC)
Hydraulic-model complexity
Stomatal-model representation
Analytic solution and estimation
Whole-plant vulnerability "curve"
Temperature effects
Plant hydraulics is often misrepresented in topical research. We highlight the commonly seen ambiguities and/or mistakes, with equations and figures to help visualize the potential biases. We recommend careful thinking when using or modifying existing plant hydraulic terms, methods, and models.
Plant hydraulics is often misrepresented in topical research. We highlight the commonly seen...

redpajama_set_name: RedPajamaCommonCrawl


In my opinion, your bedroom should be your sanctuary. It should be where you want to go at the end of a long day. Remember when you were a teenager and your bedroom was your place to escape the world? Why shouldn't your adult bedroom be the same? Hopefully your style has evolved since you were 16, but having a place to decompress from the stresses of life is so important.
On days when I feel like I am maxed out, being able to walk into my room and feel calm and peace helps me to recharge so I can be the best wife and mother possible.
Before Steve retired, we moved around quite a bit, and I was always guilty of decorating the bedroom last. The kitchen and living rooms always seem more fun to decorate and feel more important because those are the rooms that everyone else will see. But not in this house! I learned my lesson and made a conscious effort to pay attention to it from the start of this move-in process.
I love white bedding (shocker)! You know that feeling of walking into a clean and fresh hotel? Well, I love that feeling and now I have it every time I walk into my bedroom! It's almost like being on vacation.....kinda.
I like to go with simple duvet and sheets so that I can change up the pillows and throw blanket when I am wanting a fresh look or if I want to match the season. I know you've asked about these before and it breaks my heart that I can't tell you where to get the exact ones. I scored these babies at HomeGoods almost 7 years ago for $39.00 each and put them in my cart faster than you can imagine.
My original wall color was Hail Navy by Benjamin Moore but then when the closet was getting painted, I decided it would look better to pull that color through into the bedroom. So now the walls are Classic Gray by Benjamin Moore and I couldn't be happier. It's so bright and fresh now!
The benches at the foot of the bed are a HomeGoods find for $29.99 each and I had them recovered to match. You should have seen them before, they were bright teal, but I knew that had great potential. I'm telling you guys, HomeGoods is my place to find all the little accessories that make a room unique. I love having a little seating area at the end of the bed to place things, yet often times they are layered with folded laundry or Steve's shirt at the end of the day. Hey if nothing else.. they're the prettiest little catch alls, right?
My friend and designer, Annie helped me pull together a lot of the larger bedroom pieces I have now. We both aren't huge on matchy match bedroom sets. I want to love each piece of furniture by itself and as a part of the room. That's why I enjoy the hunt so much, and watching it all come together is so rewarding.
I am not a fan of a cluttered bedside table, just a lamp, a cute vase and a phone charger is all I really need. Plus it is easy to keep clean. To me less, is more. Remember, this is a stress free zone, because clutter just makes me anxious. So glancing over to a mess as I try to settle down and unwind, would not work for me. With nothing there, there's nothing to think about.
Something that people get worried about is how to make the bed. But what I always tell people and remind myself of is that you can always find a picture of a bed or replicate one on display you've seen. Garb a picture with your phone and recreate it. Grab some similar sheets, pillows, duvet and you're all set. Just have fun with it and make sure your bedroom is a place you love!


text:
Dudson White
Evo Origins
Harvest Norse
The Maker's Collection – Urban
The Maker's Collection – Finca
Why Dudson?
Performance Delivered
The 8 reasons why a Dudson plate is made to last
Dudson is a heritage brand dating back to 1800 and to this day, is still made by renowned potters in Stoke-on-Trent, the world capital of ceramics. Every step in the process is practiced and refined.
From the sourcing of raw materials and unique formulation of the clay body, to shape engineering and numerous quality checks ensuring that Dudson products work as hard as you do.
1. Performance Materials
Our unique clay recipe is essential in creating a strong and durable product for the hospitality industry. Our raw materials are selected to deliver the optimum balance of strength and whiteness.
Our clay comes from Devon and Cornwall in the UK and we work closely with our suppliers to ensure continuity of supply. Geologically there is over 100 years worth of supply at our clay source.
Alumina or Aluminium Oxide is the chemical compound of aluminium and oxygen with the chemical formula AL2O3. Alumina adds superior strength and whiteness and has shock absorbent qualities that combined with other components improves the products performance in use.
2. Engineered Shape & Form
Every piece of Dudson's ceramic is designed with performance in mind. Through expert shape engineering, we reinforce strength and durability while continual investment in technology guarantees functionality and consistent quality
100% of unused clay is recovered and recycled.
A combination of extensive industry knowledge and continual investment in leading manufacturing technology ensures the product is kept at an optimum weight for both functionality and durability. The technology used to form our products ensures consistency in size and weight allowing pieces to be stacked back of house using less space and reducing breakages.
3. Vitrification & Firing
100% of Dudson's ceramics are vitrified which is essential to the hospitality industry. Vitrification is a process where we physically change the clay, melting it to make our ceramics impervious to water, which also means that bacteria has less opportunity to
penetrate into the ceramics and grow.
Breakages in ceramics are generally related to porosity, or how much water a piece can absorb. Water absorption weakens the chemical structure affecting its durability over time. Through the process of Vitrification, the particle structure of our ceramic body becomes strong, dense and watertight.
4. Glazing
Our glaze is hard wearing and designed specifically for the hospitality environment. The durability is a combination of the glaze recipe, the firing temperature and substrate.
Harvest and The Maker's Collection designs are hand dipped, this enhances the artisan look of the products, creating original 'maker's marks' on the reverse of each piece.
Glazing the base requires 'pin-firing'. This is when the peice sits on a crank to ensure the glaze coats the full base. The crank leaves small marks behind called 'maker's marks' signifying that the piece has a glazed base. Our fully glazed base can reduce surface scratching when the product is stacked.
5. Quality & Conformance
Dudson ceramics are continuously tested and quality checked, from the stage of raw materials, throughout the manufacturing process to the final fired piece.
We are a member of the BCC (British Ceramic Confederation), one of the leading bodies in ceramics and test daily in our in house UKAS accredited lab.
We test dishwasher durability to British Hospitality Standard BS 12875. In service testing has demonstrated that under hospitality use, this is the equal to 5000 dishwasher cycles. Our continuous improvement program ensures we aim to constantly improve the quality of our products.
6. Design Innovation
Dudson are experts in ceramic design and at the forefront of innovation. Our entire product portfolio is designed in the UK by our experienced and talented design team.
Dudson have launched over 400 products since 2019.
We are continually developing materials that bring colour, texture and pattern to the tabletop without compromising on the durability that the hospitality industry demands.
A perfect balance of machinery and people. We combine up to date manufacturing technologies with historical ceramic techniques in order to innovate with design.
7. Service & Stock
At Dudson we are dedicated to reliability, ensuring our product is in stock and delivered on time. We pride ourselves on our stock levels and ability to deliver on time, all around the world.
Our 130,000sq ft warehouse stores over seven million products. We process 44,000 cartons of product weekly across multiple brands, that's an average of 72,000 pieces everyday.
We have warehouses located in:
Stoke-on-Trent, UK
8. History & Heritage
A heritage brand dating back to 1800, Dudson is made by renowned potters in the heart of Stoke on Trent, the world capital of ceramics.
Our home Stoke on Trent is the world capital of ceramics. The city is known globally as 'The Potteries.
Our past has shaped our future, established in 1800, the Dudson brand continues to grow and innovate. We have evolved and adapted to changes in the marketplace, introducing multiple manufacturing routes to produce colour and texture as well as investing in new technology to create differentiated shapes.
The Dudson ceramic body is industrially tough, we blend centuries of experience with cutting edge technology and design innovation to produce one of the strongest ceramic bodies in the world.
This brochure outlines the many
reasons why Dudson products are made to last.
Available as PDF
Edge Chip Warranty
* Selected products covered by a five year edge chip warranty. Terms and conditions apply.
churchill1795.com
® Dudson is a registered trademark of Churchill China PLC (Since April 2019)


text:
Ken Corday Provides Updates on Days of Our Lives
Carly Silver
Ken Corday
Days of Our Lives' head honcho Ken Corday spoke to Soap Opera Digest about actor departures and returns and the show's return to filming.
Fans can expect some departing stars to return in the future. Corday teased:
Victoria Konefal [Ciara] has left ... and will return ... and will leave, so she'll be coming and going. But we haven't seen the last of her. Chandler Massey [Will] and Freddie Smith [Sonny] are leaving, but they will also be returning on and off. It's not like they are leaving, good-bye forever. It's something we don't like doing, closing the door permanently.
The break in production has also forced some changes in DAYS' filming schedule. Corday dished:
Well, we'll be a month in front of air. We'll start with five shows a week, get our speed and pace up, and if that works well, we'll go to six, and if that works well, we'll go to seven and get further ahead of air because you never know when you're going to have to shut down again. And we do not want to go to second-runs. It's just too expensive. It's too expensive for the network not to get first-run advertising dollars.
Ken CordayChandler MasseyNBC DaytimeVictoria KonefalFreddie SmithDays of Our Lives
Ken Corday on Upcoming Exits: "No One Ever Really Dies on Days of Our Lives"
By Carly Silver
Days of Our Lives' Ken Corday Reveals All
DAYS' Ron Carlivati Provides Writing Updates
WATCH: Ken Corday Discusses His All-Time Favorite Days of Our Lives Storyline


text:
Rabofsky ist der Familienname folgender Personen:

 Alfred Rabofsky (1919–1944), österreichischer Schriftsetzer, Sanitätsunteroffizier und Widerstandskämpfer gegen den Nationalsozialismus
 Eduard Rabofsky (1911–1994), österreichischer Jurist und Widerstandskämpfer gegen den Nationalsozialismus

Siehe auch:
 Karl Rabofsky, deutsches Maschinenbauunternehmen

redpajama_set_name: RedPajamaWikipedia