Sparsest factor analysis for clustering variables: a matrix decomposition approach

We propose a new procedure for sparse factor analysis (FA) such that each variable loads only one common factor. Thus, the loading matrix has a single nonzero element in each row and zeros elsewhere. Such a loading matrix is the sparsest possible for certain number of variables and common factors. For this reason, the proposed method is named sparsest FA (SSFA). It may also be called FA-based variable clustering, since the variables loading the same common factor can be classified into a cluster. In SSFA, all model parts of FA (common factors, their correlations, loadings, unique factors, and unique variances) are treated as fixed unknown parameter matrices and their least squares function is minimized through specific data matrix decomposition. A useful feature of the algorithm is that the matrix of common factor scores is re-parameterized using QR decomposition in order to efficiently estimate factor correlations. A simulation study shows that the proposed procedure can exactly identify the true sparsest models. Real data examples demonstrate the usefulness of the variable clustering performed by SSFA

Use of organic inputs by arable farmers in six agro-ecological zones across Europe: Drivers and barriers

Soil organic matter (SOM) in agricultural soils builds up via – among others - the use of organic inputs such as straw, compost, farmyard manure or the cultivation of green manures or cover crops. SOM has benefits for long-term soil fertility and can provide ecosystem services. Farmer behaviour is however known to be motivated by a larger number of factors. Using the theory of planned behaviour, we aimed to disentangle these factors. We addressed the following research question: What are currently the main drivers and barriers for arable farmers in Europe to use organic inputs? Our study focuses on six agro-ecological zones in four European countries (Austria, Flanders [Belgium], Italy and the Netherlands) and four practices (straw incorporation, green manure or cover crops, compost and farmyard manure). In a first step, relevant factors were identified for each practice with farmers using 5 to ten semi-structured interviews per agro-ecological zone. In a second step, the relevance of these factors was quantified and they were classified as either drivers or barriers in a large scale farm survey with 1263 farmers. In the semi-structured interviews, 110 factors that influenced farmer decisions to use an organic input were identified. In the larger farm survey, 60% of the factors included were evaluated as drivers, while 40% were evaluated as barriers for the use of organic inputs. Major drivers to use organic inputs were related to the perceived effects on soil quality (such as improved soil structure or reduced erosion) and the positive influence from social referents (such as fellow farmers or agricultural advisors). Major barriers to use organic inputs were financial (increased costs or foregone income) and perceived effects on crop protection (such as increased weeds, pests and diseases, or increased pesticide use). Our study shows that motivating farmers to use organic inputs requires specific guidance on how to adapt cultivation practices to reduce weeds, pests and diseases for specific soil types, weather conditions, and crops. In addition, more research is needed on the long-term financial consequences of using organic inputs

Assessment of conjunctival, episcleral and scleral thickness in healthy individuals using anterior segment optical coherence tomography

Purpose: To determine the thickness of the conjunctiva, episclera and sclera in healthy individuals using anterior segment optical coherence tomography (AS-OCT).Methods: We prospectively included 107 healthy individuals of different age groups (18-39 years, 40-54 years, 55-69 years and >= 70 years). For each eye, AS-OCT scans of four quadrants (temporal, nasal, superior and inferior) were acquired. The thickness of the conjunctiva, episclera and sclera was measured for each scan. In addition, the axial length of both eyes was measured, and general characteristics, including smoking, allergies and contact lens use, were collected.Results: The mean conjunctival thickness was significantly different between the nasal and superior quadrants (87 +/- 30 mu m vs. 77 +/- 16 mu m; p < 0.001), as well as the superior and inferior quadrants (77 +/- 16 mu m vs. 86 +/- 19 mu m; p = 0.001). The mean episcleral thickness was larger in the superior (174 +/- 54 mu m) and inferior (141 +/- 43 mu m) quadrants, compared to the nasal (83 +/- 38 mu m) and temporal quadrants (90 +/- 44 mu m). The mean scleral thickness of the inferior quadrant was the largest (596 +/- 64 mu m), followed by the nasal (567 +/- 76 mu m), temporal (516 +/- 67 mu m) and superior (467 +/- 52 mu m) quadrants (all p < 0.001). The averaged scleral thickness increased 0.96 mu m per age year (0.41-1.47 mu m, p < 0.001).Conclusions: This study provides an assessment of the thickness of scleral and adjacent superficial layers in healthy individuals determined on AS-OCT, which could enable future research into the use of AS-OCT in diseases affecting the anterior eye wall

Assessment of conjunctival, episcleral and scleral thickness in healthy individuals using anterior segment optical coherence tomography

Purpose: To determine the thickness of the conjunctiva, episclera and sclera in healthy individuals using anterior segment optical coherence tomography (AS-OCT).Methods: We prospectively included 107 healthy individuals of different age groups (18-39 years, 40-54 years, 55-69 years and >= 70 years). For each eye, AS-OCT scans of four quadrants (temporal, nasal, superior and inferior) were acquired. The thickness of the conjunctiva, episclera and sclera was measured for each scan. In addition, the axial length of both eyes was measured, and general characteristics, including smoking, allergies and contact lens use, were collected.Results: The mean conjunctival thickness was significantly different between the nasal and superior quadrants (87 +/- 30 mu m vs. 77 +/- 16 mu m; p < 0.001), as well as the superior and inferior quadrants (77 +/- 16 mu m vs. 86 +/- 19 mu m; p = 0.001). The mean episcleral thickness was larger in the superior (174 +/- 54 mu m) and inferior (141 +/- 43 mu m) quadrants, compared to the nasal (83 +/- 38 mu m) and temporal quadrants (90 +/- 44 mu m). The mean scleral thickness of the inferior quadrant was the largest (596 +/- 64 mu m), followed by the nasal (567 +/- 76 mu m), temporal (516 +/- 67 mu m) and superior (467 +/- 52 mu m) quadrants (all p < 0.001). The averaged scleral thickness increased 0.96 mu m per age year (0.41-1.47 mu m, p < 0.001).Conclusions: This study provides an assessment of the thickness of scleral and adjacent superficial layers in healthy individuals determined on AS-OCT, which could enable future research into the use of AS-OCT in diseases affecting the anterior eye wall

The effect of high dose inhaled corticosteroids on wheeze in infants after respiratory syncytial virus infection: randomised double blind placebo controlled trial

Objective To determine whether early initiated anti-inflammatory therapy with prolonged high dose inhaled glucocorticoids influences the occurrence and severity of recurrent wheeze after respiratory syncytial virus related lower respiratory tract infections

The contribution of cytomegalovirus infection to immune senescence is set by the infectious Dose

Stemcel biology/Regenerative medicine (incl. bloodtransfusion

The Role of Spatially Controlled Cell Proliferation in Limb Bud Morphogenesis

Oriented cell behaviors likely have a more important role in limb bud elongation during development than previously suggested by the “growth-based morphogenesis” hypothesis