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| 3. |
- Berg, Christina, 1963, et al.
(author)
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Sources of bias in a dietary survey of children.
- 1998
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In: European journal of clinical nutrition. - 0954-3007. ; 52:9, s. 663-7
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Journal article (peer-reviewed)abstract
- OBJECTIVE: To compare non-responders and responders to a dietary survey with respect to demographic variables and intention to choose selected breakfast foods, and to examine if there was any systematic change in number of food items reported during a 7 d recording period. DESIGN: Cross-sectional survey. SETTING: Mölndal, Sweden. SUBJECTS: All pupils in 5th, 7th and 9th grades in the municipality were asked to complete a questionnaire during school hours. All those present (n = 1584, 92% of total) answered questions about lifestyle factors and about intentions, attitudes and beliefs concerning high-fibre bread and milk with varying fat content. All subjects in the initial sample were asked to fill in a 7 d record of food consumed. Acceptable food records were completed by 69% of the initial participants. RESULTS: Subjects not completing the food record differed significantly from participants with respect to demographic, lifestyle and dietary factors. Dropout was more common among those who reported not usually eating breakfast and among those intending to drink whole milk for breakfast. A decline in reported food items during the recording period was also observed. CONCLUSIONS: Two sources of bias were observed here, one indicating significant differences between non-participants and participants, the other suggesting the presence of a time-dependent trend in number of recorded foods. It is likely such biases are present in other dietary surveys involving schoolchildren, and should be taken into consideration in the design, analysis and interpretation of such studies.
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| 4. |
- Bernes, Claes, et al.
(author)
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Manipulating ungulate herbivory in temperate and boreal forests : Effects on vegetation and invertebrates. A systematic review
- 2018
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In: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 7:1
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Research review (peer-reviewed)abstract
- Background: Livestock grazing and 'overabundance' of large wild herbivores in forested areas have long been perceived as conflicting with the aims of both silviculture and forest conservation; however, certain kinds of herbivory can help to maintain habitat values in forest ecosystems. Management of mammalian herbivory in protected forests can, therefore, be a critical tool for biodiversity conservation. The primary aim of this systematic review was to examine how forest vegetation and invertebrates are affected by manipulation of the grazing/browsing pressure by livestock or wild ungulates. The ultimate purpose was to investigate whether such manipulation is useful for conserving or restoring biodiversity in forest set-asides. Methods: We considered studies of manipulated ungulate herbivory in forests anywhere within the boreal and temperate zones, not only in protected areas but also in production forest. Non-intervention or alternative levels of intervention were used as comparators. Relevant outcomes included abundance, diversity and composition of plants and invertebrates, tree regeneration, and performance of focal/target species. Studies were mainly selected from a recent systematic map of the evidence on biodiversity effects of forest management relevant to protected areas. Additional studies were identified through updated searches online and in bibliographies of existing reviews. Relevant studies were critically appraised, and studies with low or unclear validity were excluded from the review. Quantitative outcomes were extracted from 103 articles, and summary effect sizes were derived by meta-analysis. Results: Most of the 144 studies included in the review had been conducted in North America, Europe or Australia/New Zealand. The intervention most commonly studied was experimental exclusion (or enclosure) of wild and/or domestic ungulates by fencing. Other studies examined culling of wild ungulates or compared forests long grazed by livestock to ungrazed forests. Effects on vegetation and invertebrates were reported in 135 and 23 of the studies, respectively. We found negative responses to herbivory in the abundance of understorey vegetation as a whole, woody understorey and bryophytes, and also in the species richness of woody understorey vegetation, whereas the richness of forbs and bryophytes responded positively. Several effects depended on ungulate origins: Understorey abundance responded negatively to livestock and to ungulates introduced into the wild, but not to native ones. In contrast, understorey species richness responded positively to livestock but not to wild ungulates. The duration and intensity of herbivory had few significant effects on vegetation - exceptions included woody understorey abundance and richness, which decreased with increasing duration and intensity, respectively. Among invertebrates we found negative responses to herbivory in the abundance of lepidopterans and spiders, but no significant effects on species richness. Conclusions: Our review revealed a large body of high-validity experimental studies on impacts of ungulate herbivory in forests. This evidence confirmed that manipulation of such herbivory is often highly influential on tree regeneration and on the abundance, diversity and composition of understorey vegetation. Nevertheless, we also identified important knowledge gaps - we found few studies of boreal areas, long-term herbivory effects, impacts on bryophytes, lichens and invertebrates, and effects of manipulation less radical than total exclusion of ungulates.
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- Bernes, Gun, et al.
(author)
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Positive deviant strategies implemented by organic multi-species livestock farms in Europe
- 2022
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In: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 201
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Journal article (peer-reviewed)abstract
- CONTEXT: Transitions to more sustainable livestock production systems are increasingly demanded by parts of society. Scientists suggest moving towards diversified farming systems due to their potential environmental and economic benefits, especially in the organic sector. However, empirical knowledge of multi-species livestock farms, i.e. farms keeping two or more animal species, is lacking.OBJECTIVE: Our objectives were to identify European organic multi-species livestock farms that outperform their peers despite having the same resources and constraints, and characterize their distinctive management principles.METHODS: We conducted surveys on 102 farms in seven European countries: Austria, Belgium, France, Ger-many, Italy, Sweden and Switzerland. We restricted the analysis to a sub-sample of 75 farms that had complete data and that covered 3 main livestock combinations (cattle and sheep, cattle and pigs, cattle and poultry) with similar number of farms. We implemented a positive deviant approach based on three indicators: land pro-ductivity, nitrogen input dependence and satisfaction regarding income.RESULTS AND CONCLUSIONS: Five structurally diverse positive deviant farms were identified with 4 types of livestock combinations represented, and farmland area ranging from 25 to 273 ha, herd size from 33 to 146 livestock units (LU) and total workforce size from 1 to 24 annual worker units (AWU). These farms were located on a trade-off between land productivity and autonomy for feed, and all but one had high overall autonomy for feed (89-100% against a mean of 76% for the whole sample). Their diversity of pastures, crops and livestock species and their diversification beyond agricultural production were controlled (e.g. no agritourism) and below that of the other sample farms, to remain manageable by the farmers while still allowing to buffer shocks and hazards. Interactions among farm enterprises remained limited to matter (mainly grain, straw, hay, manure) flows, and practices requiring specific efforts and investments (e.g. for fencing), such as co-grazing of different livestock and crop residues grazing, were avoided.SIGNIFICANCE: We conducted the first integrated study on European organic multi-species livestock farms and identified key management principles implemented on positive deviant farms. We showed that whatever their size, farms outperforming their peers do not necessarily maximize diversity of agricultural productions and of non-agricultural activities, and interactions among farm enterprises but that they remain at a level of complexity manageable by the farmers. These principles will inform farmers running multi-species livestock farms or transitioning to this model.
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| 8. |
- Bernes, Gun, et al.
(author)
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Sheep fed only silage or silage supplemented with concentrates 2. Effects on lamb performance and fatty acid profile of ewe milk and lamb meat
- 2012
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In: Small Ruminant Research. - : Elsevier BV. - 0921-4488. ; 102, s. 114-124
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Journal article (peer-reviewed)abstract
- Production performance of ewes fed only silage, or silage supplemented with a maximum of 50% concentrates (barley, peas, rapeseed cake), from mid-gestation until weaning was evaluated during two years. Lambs had access to the same diets as their dams while nursing. Ewe milk samples were collected at weeks 2 and 4 after lambing to evaluate the dietary influence on the fatty acid (FA) profile. After weaning, lambs from each ewe feeding programme either continued on the same diet or were switched to the other and the study continued for an additional five weeks year 1 (Y1) and seven weeks year 2 (Y2). Feed intake, weight gain and body condition of the lambs were recorded. At slaughter, muscle samples were taken to study the FA profile. The silage fed during Y2 was lower in crude protein content and contained more indigestible neutral detergent fibre and a higher amount of acids than the silage fed in Y1. The intake level of the lambs, particularly those fed only silage, was generally lower in Y2. In both years, weight gain was highest in the lamb groups fed concentrates after weaning and lowest in the group fed only silage. The FA profiles of milk and lamb muscle were influenced by the diet and nutritional status of the ewes. Milk from silage-fed ewes was higher in Cl 8:3n-3 and conjugated linoleic acid, whereas milk from concentrate-fed ewes was higher in C18:0 and C18:2n-6. In Y1 the muscle of lambs fed concentrates pre-weaning had lower C16:0 and higher C18:1c-9 levels. The influence of diet on lamb muscle FA profile was less pronounced in Y2. In both years the C18:3n-3 levels were lower in muscle from lambs fed concentrates. In conclusion, the FA profile of lamb muscle was strongly influenced by the ewe diet and milk FA profile. Lambs on the same pre-weaning diet had a more similar profile than lambs with the same post-weaning diet. Feeding intensity and duration were the factors influencing the lamb muscle FA profile. A diet with only silage produced meat with a higher proportion of n-3 FA beneficial for human health; however, the lamb nutritional requirements for optimal growth were difficult to meet even with high-nutrient-quality silage. (C) 2011 Elsevier B.V. All rights reserved.
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| 9. |
- Botella, Pablo, PhD Student, 1988-
(author)
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Physical Properties of Ternary Metal Oxides and Carbon Nanomaterials Under Pressure
- 2020
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Doctoral thesis (other academic/artistic)abstract
- Found in nature or synthesized, materials present amazing properties such as superconductivity, super-hardness, lightweight, or high-energy-density, among others. All these properties can be used in our benefit to improve or develop new applications. Although, many of these properties are not noticeable in the ambient conditions of pressure and temperature. Therefore, only when the materials are exposed to extreme conditions of temperature, pressure, radiation, etc., become notable. For those reasons, it is fundamental to understand their properties and how they are affected by different parameters such as the synthesis process, morphology, doping or external parameters (e.g. pressure, temperature).High-pressure studies have been shown to be an excellent tool for proving and study the robustness of material properties as well as for the synthesis of new materials. Changes as extreme and spectacular as converting oxygen gas into a superconducting metal or the well-known graphite to diamond conversion among others have been made under high-pressure conditions.Among all the materials, and due to their interesting properties, in this doctoral thesis we have studied four ternary metal oxide semiconductors (InVO4, CrVO4, InNbO4 and InTaO4) and carbon nanostructure materials (single-walled carbon nanotubes (SWCNTs)) at ambient conditions as well as under high-pressure (static or dynamic compression) using different characterization techniques such as X-ray diffraction (XRD), Raman spectroscopy (RS), optical absorption, transmission electron microscopy (TEM), photoluminescence (PL) and electrical measurements.InVO4, InNbO4 and InTaO4 are wide metal oxide semiconductors having band-gap energy of 3.62(5), 3.63(5) and 3.79(5) eV, respectively, being InVO4 a direct band-gap semiconductor and, InNbO4 and InTaO4 indirect band-gap semiconductors. These compounds undergo, under pressure, to a structural phase transition from orthorhombic, in the case of InVO4, or monoclinic, in the case of InNbO4 and InTaO4, to another monoclinic system. This structural phase transition triggers interesting phenomena due to the modification of the electronic band structure of the compounds. Phenomena observed under compression include bandgap collapse about 1-1.5 eV depending on the compound, band crossing due to the change to the local maximum on top of the valence band and colour change. Also, the electrical resistivity of the materials is affected by this change in the band structure. All these results are discussed based on our theoretical band structure calculations.On the other hand, doping these compounds below 0.2% using Tb or Yb rare-earth elements, the crystal structure is barely affected as well as their phonon structure, but the band structure does, giving rise optical excitation and emission properties in the visible and near-infrared (NIR) spectral region. From optical reflectivity measurements, the two first direct transitions are reported at 3.7/4.2 eV in InVO4, 4.7/5.3 eV in InNbO4 and 5.6/6.1 eV in InTaO4. All the compounds present self-activated photoemission signals which are discussed in terms of the distorted polyhedral coordination around V, Nb and Ta atoms. Finally, the characteristic emission of Tb atoms in the green region (5D4→7FJ) and the Yb atoms in the NIR region (2F5/2→2F7/2) are analysed and discussed based on our theoretical calculations.Even though, being a prototype structure of a family of compounds denoted as CrVO4-type materials, there is still scarce information on the behaviour under pressure of the CrVO4 compound. Here, it is also studied CrVO4 having an orthorhombic structure under pressure up to 10 GPa. Crystal structure, phonon band structure, optical and electrical properties are analysed showing a structural phase transition similar to that in InVO4 with an increase in the vanadium atoms coordination from 4 to 6. This phase transition triggers also a band-gap collapse of 1.1 eV, a change in the phonon structure and a sharp decrease in the resistivity of the material. All these results are discussed in terms of our theoretical calculations and comparison with its isostructural partner InVO4.To conclude, we study the effects of the dynamic pressure of 0.5 Mbar (50 GPa) on SWCNTs which is way beyond the limit of their structural stability in quest of new forms of carbon nanostructures. Thus, no nanotubes survived to this pressure. The recovered material is composed of two types of material which are classified in a multi-layer graphene phase (MLG) with high defect concentration and multi-phase material which dominates the sample. Even the reached conditions during the shock-compression were favourable for the diamond formation, we were unable to find traces of diamond-like carbon in the very inhomogeneous sample. The crystal size of both materials has been estimated at 13 nm for disordered carbon and 30 nm for MLG phase. The dispersion of the Raman modes was also studied using several lasers and the observations were supported by TEM analysis.
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| 10. |
- Botella, Pablo, et al.
(author)
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Single-Walled Carbon Nanotubes Shock-Compressed to 0.5 Mbar
- 2017
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In: Physica status solidi. B, Basic research. - : John Wiley & Sons. - 0370-1972 .- 1521-3951. ; 254:11
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Journal article (peer-reviewed)abstract
- Single-walled carbon nanotubes (SWCNTs) have been dynamically (shock) compressed to 0.5 Mbar, above the limit of their structural integrity. Two distinct types of material are identified by high-resolution transmission electron microscopy (HRTEM) and multi-wavelength Raman spectroscopy in the sample recovered after shock: multi-layer graphene (MLG) and a two-phase material composed of nano-clustered graphene and amorphous carbon whereas no diamond-like carbon or carbon nano-onions are found. Peak decomposition of the Raman spectra was used to estimate the coherent scatterers (clusters) size in MLG at 36 nm from the D- to G-band intensity ratio dependence on the photon excitation energy. Botella et al. (article no. 1700315) propose the peak fitting model for decomposition of the Raman spectra of highly disordered carbon material containing graphene nano-clusters and stress the importance of accounting for heptagonal- and pentagonal-ring defects in graphene layers for the analysis of such spectra. The cover image shows HRTEM images and the correspondent Raman spectra of the two types of material along with peak decomposition of the two-phase material with the peaks assigned to heptagons (a) and pentagons (b). Particulars of the SWCNTs transformation to other structural forms of carbon at high pressure/temperature are discussed
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