This book treats the technology of radar imaging for remote sensing applications in a manner suited to the mathematical background of most earth scientists. It assumes no prior knowledge of radar on ...the part of the reader, instead it commences with a development of the essential concepts of radar before progressing through to a detailed coverage of contemporary ideas such as polarimetry and interferometry. Because the technology of radar imaging is potentially complex the first chapter provides a framework against which the rest of the book is set. Together, the first four chapters present the technical foundations for remote sensing with imaging radar. Scattering concepts are then covered so that the reader develops the knowledge necessary for interpreting radar data, itself the topic of a later chapter which draws together the current thinking in the analysis of radar imagery. The treatment is based on the assumption that the radars of interest are, in general, multi-polarised. Polarisation synthesis and polarised interferometric SAR are among the topics covered, as are tomography and the various forms of interferometry. A full chapter is given to bistatic radar, which is now emerging as an imaging technology with enormous potential and flexibility in remote sensing. The book concludes with a summary of passive microwave imaging. A set of appendices is included that provide supplementary material, among which is an overview of the rather complicated process of image formation with synthetic aperture radar, and summaries of some of the mathematical procedures important for a full appreciation of radar as a remote sensing technology.
Remote Sensing Digital Image Analysis provides the non-specialist with an introduction to quantitative evaluation of satellite and aircraft derived remotely retrieved data. Each chapter covers the ...pros and cons of digital remotely sensed data, without detailed mathematical treatment of computer based algorithms, but in a manner conductive to an understanding of their capabilities and limitations. Problems conclude each chapter. This fourth edition has been developed to reflect the changes that have occurred in this area over the past several years. Its focus is on those procedures that seem now to have become part of the set of tools regularly used to perform thematic mapping. As with previous revisions, the fundamental material has been preserved in its original form because of its tutorial value; its style has been revised in places and it has been supplemented if newer aspects have emerged in the time since the third edition appeared. It still meets, however, the needs of the senior student and practitioner.
Since screening programs identify only a small proportion of the population as eligible for an intervention, genomic prediction of heritable risk factors could decrease the number needing to be ...screened by removing individuals at low genetic risk. We therefore tested whether a polygenic risk score for heel quantitative ultrasound speed of sound (SOS)-a heritable risk factor for osteoporotic fracture-can identify low-risk individuals who can safely be excluded from a fracture risk screening program.
A polygenic risk score for SOS was trained and selected in 2 separate subsets of UK Biobank (comprising 341,449 and 5,335 individuals). The top-performing prediction model was termed "gSOS", and its utility in fracture risk screening was tested in 5 validation cohorts using the National Osteoporosis Guideline Group clinical guidelines (N = 10,522 eligible participants). All individuals were genome-wide genotyped and had measured fracture risk factors. Across the 5 cohorts, the average age ranged from 57 to 75 years, and 54% of studied individuals were women. The main outcomes were the sensitivity and specificity to correctly identify individuals requiring treatment with and without genetic prescreening. The reference standard was a bone mineral density (BMD)-based Fracture Risk Assessment Tool (FRAX) score. The secondary outcomes were the proportions of the screened population requiring clinical-risk-factor-based FRAX (CRF-FRAX) screening and BMD-based FRAX (BMD-FRAX) screening. gSOS was strongly correlated with measured SOS (r2 = 23.2%, 95% CI 22.7% to 23.7%). Without genetic prescreening, guideline recommendations achieved a sensitivity and specificity for correct treatment assignment of 99.6% and 97.1%, respectively, in the validation cohorts. However, 81% of the population required CRF-FRAX tests, and 37% required BMD-FRAX tests to achieve this accuracy. Using gSOS in prescreening and limiting further assessment to those with a low gSOS resulted in small changes to the sensitivity and specificity (93.4% and 98.5%, respectively), but the proportions of individuals requiring CRF-FRAX tests and BMD-FRAX tests were reduced by 37% and 41%, respectively. Study limitations include a reliance on cohorts of predominantly European ethnicity and use of a proxy of fracture risk.
Our results suggest that the use of a polygenic risk score in fracture risk screening could decrease the number of individuals requiring screening tests, including BMD measurement, while maintaining a high sensitivity and specificity to identify individuals who should be recommended an intervention.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Evidence suggests that affective problems, such as depression and anxiety, increase risk for late-life dementia. However, the extent to which affective problems influence cognitive decline, even many ...years prior to clinical diagnosis of dementia, is not clear. The present study systematically reviews and synthesises the evidence for the association between affective problems and decline in cognitive state (i.e., decline in non-specific cognitive function) in older adults. An electronic search of PubMed, PsycInfo, Cochrane, and ScienceDirect was conducted to identify studies of the association between depression and anxiety separately and decline in cognitive state. Key inclusion criteria were prospective, longitudinal designs with a minimum follow-up period of 1 year. Data extraction and methodological quality assessment using the STROBE checklist were conducted independently by two raters. A total of 34 studies (n = 71 244) met eligibility criteria, with 32 studies measuring depression (n = 68 793), and five measuring anxiety (n = 4698). A multi-level meta-analysis revealed that depression assessed as a binary predictor (OR 1.36, 95% CI 1.05–1.76, p = 0.02) or a continuous predictor (B = −0.008, 95% CI −0.015 to −0.002, p = 0.012; OR 0.992, 95% CI 0.985–0.998) was significantly associated with decline in cognitive state. The number of anxiety studies was insufficient for meta-analysis, and they are described in a narrative review. Results of the present study improve current understanding of the temporal nature of the association between affective problems and decline in cognitive state. They also suggest that cognitive function may need to be monitored closely in individuals with affective disorders, as these individuals may be at particular risk of greater cognitive decline.
Amyotrophic lateral sclerosis (ALS) is a progressive, degenerative neuromuscular disease with limited treatment options. The diagnosis of ALS can be challenging for numerous reasons, resulting in ...delays that may compromise optimal management and enrollment into clinical trials. Several studies have examined the process and challenges regarding the clinical diagnosis of ALS. Twenty-one studies that were almost exclusively from the English literature published between 1990 and 2020 were identified via PubMed using relevant search terms and included patient populations from the United States, Canada, Japan, Egypt, and several countries in South America and Europe. Probable or definitive ALS patients were identified using El Escorial or revised El Escorial/Airlie House Criteria. Time to diagnosis or diagnostic delay was defined as mean or median time from patient-reported first symptom onset to formal diagnosis by a physician, as recorded in medical records. The typical time to diagnosis was 10–16 months from symptom onset. Several points of delay in the diagnosis course were identified, including specialist referrals and misdiagnoses, often resulting in unnecessary procedures and surgeries. Bulbar onset was noted to significantly reduce time to ALS diagnosis. Future interventions and potential research opportunities were reviewed.
•Typical time to ALS diagnosis in the literature review was 10–16 months from symptom onset•Specialist referrals and misdiagnoses were key factors leading to diagnostic delay, often resulting in unnecessary procedures•Bulbar onset of ALS was noted to significantly reduce time to diagnosis•Referral to a neurologist was not consistently found to reduce diagnostic delay
Osteocytes are master regulators of the skeleton. We mapped the transcriptome of osteocytes from different skeletal sites, across age and sexes in mice to reveal genes and molecular programs that ...control this complex cellular-network. We define an osteocyte transcriptome signature of 1239 genes that distinguishes osteocytes from other cells. 77% have no previously known role in the skeleton and are enriched for genes regulating neuronal network formation, suggesting this programme is important in osteocyte communication. We evaluated 19 skeletal parameters in 733 knockout mouse lines and reveal 26 osteocyte transcriptome signature genes that control bone structure and function. We showed osteocyte transcriptome signature genes are enriched for human orthologs that cause monogenic skeletal disorders (P = 2.4 × 10
) and are associated with the polygenic diseases osteoporosis (P = 1.8 × 10
) and osteoarthritis (P = 1.6 × 10
). Thus, we reveal the molecular landscape that regulates osteocyte network formation and function and establish the importance of osteocytes in human skeletal disease.
Osteoporosis and sarcopenia are common comorbid diseases, yet their shared mechanisms are largely unknown. We found that genetic variation near FAM210A was associated, through large genome-wide ...association studies, with fracture, bone mineral density (BMD), and appendicular and whole body lean mass, in humans. In mice, Fam210a was expressed in muscle mitochondria and cytoplasm, as well as in heart and brain, but not in bone. Grip strength and limb lean mass were reduced in tamoxifen-inducible Fam210a homozygous global knockout mice (TFam210a
−/−), and in tamoxifen-inducible Fam210 skeletal muscle cell-specific knockout mice (TFam210aMus
−/−). Decreased BMD, bone biomechanical strength, and bone formation, and elevated osteoclast activity with microarchitectural deterioration of trabecular and cortical bones, were observed in TFam210a
−/− mice. BMD of male TFam210aMus
−/− mice was also reduced, and osteoclast numbers and surface in TFam210aMus
−/− mice increased. Microarray analysis of muscle cells from TFam210aMus
−/− mice identified candidate musculoskeletal modulators. FAM210A, a novel gene, therefore has a crucial role in regulating bone structure and function, and may impact osteoporosis through a biological pathway involving muscle as well as through other mechanisms.
Frailty in surgical patients Richards, Simon J. G.; Frizelle, Frank A.; Geddes, John A. ...
International journal of colorectal disease,
12/2018, Letnik:
33, Številka:
12
Journal Article
Recenzirano
Objective
To describe the current definitions, aetiology, assessment tools and clinical implications of frailty in modern surgical practice.
Background
Frailty is a critical issue in modern surgical ...practice due to its association with adverse health events and poor post-operative outcomes. The global population is rapidly ageing resulting in more older patients presenting for surgery. With this, the number of frail patients presenting for surgery is also increasing. Despite the identification of frailty as a significant predictor of poor health outcomes, there is currently no consensus on how to define, measure and diagnose this important syndrome.
Methods
Relevant references were identified through keyword searches of the Cochran, MEDLINE and EMbase databases.
Results
Despite the lack of a gold standard operational definition, frailty can be conceptualised as a state of increased vulnerability resulting from a decline in physiological reserve and function across multiple organ systems, such that the ability to withstand stressors is impaired. Multiple studies have shown a strong association between frailty and adverse peri-operative outcomes. Frailty may be assessed using multiple tools; however, the ideal tool for use in a clinical setting has yet to be identified. Despite the association between frailty and adverse outcomes, few interventions have been shown to improve outcomes in these patients.
Conclusion
Frailty encompasses a group of individuals at high risk of adverse post-operative outcomes. Further work exploring ways to optimally assess and target interventions towards these patients should be the focus of ongoing research.
Applications in environmental monitoring, surveillance and patrolling typically require a network of mobile agents to collectively gain information regarding the state of a static or dynamical ...process evolving over a region. However, these networks of mobile agents also introduce various challenges, including intermittent observations of the dynamical process, loss of communication links due to mobility and packet drops, and the potential for malicious or faulty behavior by some of the agents. The main contribution of this paper is the development of resilient, fully-distributed, and provably correct state estimation algorithms that simultaneously account for each of the above considerations, and in turn, offer a general framework for reasoning about state estimation problems in dynamic, failure-prone and adversarial environments. Specifically, we develop a simple switched linear observer for dealing with the issue of time-varying measurement models, and resilient filtering techniques for dealing with worst-case adversarial behavior subject to time-varying communication patterns among the agents. Our approach considers both communication patterns that recur in a deterministic manner, and patterns that are induced by random packet drops. For each scenario, we identify conditions on the dynamical system, the patrols, the nominal communication network topology, and the failure models that guarantee applicability of our proposed techniques. Finally, we complement our theoretical results with detailed simulations that illustrate the efficacy of our algorithms in the presence of the technical challenges described above.
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