1,128 research outputs found
Organic bioelectronic devices to control cell signalling
The nervous system consists of a network of specialized cells that coordinate the actions of
the body by transmitting information to and from the brain. The communication between the
nerve cells is dependent on the interplay of both electrical and chemical signals. As our
understanding of nerve cell signalling increases there is a growing need to develop techniques
capable of interfacing with the nervous system.
One of the major challenges is to translate
between the signal carriers of the nervous system (ions and neurotransmitters) and those of
conventional electronics (electrons). Organic conjugated polymers represent a unique class of
materials that can utilize both electrons and ions as charge carriers.
Taking advantage of this
combined feature, we have established a novel communication interface between electronic
components and biological systems. The organic bioelectronic devices presented in this thesis
are based on the organic electronic ion pump (OEIP) made of the conducting organic polymer
poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS). When
electronically addressed, electrochemical redox reactions in the polymer translate electronic
signals into electrophoretic migration of ions.
We show that the device can transport a range
of substances involved in nerve cell signaling. These include positively charged ions,
neurotransmitters and cholinergic substances. Since the devices are designed to be easily
incorporated in conventional microscopy set-ups, we use Ca2+ imaging as readout to monitor
cell responses. We demonstrate how electrophoretic delivery of ions and neurotransmitters
with precise, spatiotemporal control can be used to modulate intracellular Ca2+ signaling in
neuronal cells in the absence of convective disturbances. The electronic control of delivery
enables strict control of dynamic parameters, such as amplitude and frequency of Ca2+
responses, and can be used to generate temporal patterns mimicking naturally occurring Ca2+
oscillations.
To enable further control and fine-tuning of the ionic signals we developed the
electrophoretic chemical transistor, an analogue of the traditional transistor used to amplify
and/or switch electronic signals. We thereby take the first step towards integrated chemical
circuits.
Finally, we demonstrate the use of the OEIP in a new âmachine-to-brainâ interface.
By encapsulating the OEIP we were able to use it in vivo to modulate brainstem responses in
guinea pigs. This was the first successful realization of an organic bioelectronic device
capable of modulating mammalian sensory function by precise delivery of neurotransmitters.
Our findings highlight the potential of communication interfaces based on conjugated
polymers in generating complex, high-resolution, signal patterns to control cell physiology.
Such devices will have widespread applications across basic research as well as future
applicability in medical devices in multiple therapeutic areas
Simulation of Diamond Surface Chemistry: Reactivity and Properties
The diamond material possesses very attractive properties, such as superior electronic properties (when doped), in addition to a controllable surface termination. During the process of diamond synthesis, the resulting chemical properties will depend not only on the adsorbed species but also on the type of substitutional doping element. The combination of adsorbate and dopant will thus have the ability to influence both the chemical and electronic properties of a diamond surface. All resulting (and interesting) properties of doped and terminated diamond surfaces make it clear that these types of material modifications are very important for a variety of applications that are based on photoactivated chemical processes. Theoretical modeling has been shown to act as an important scientific tool in explaining and predicting experimental results. Simulation of the dependence of, e.g. surface termination and doping on diamond material properties, is expected to give important information about various surface electronic properties (like photo-induced surface electrochemistry)
The dual weighted residuals approach to optimal control of ordinary differential equations
The methodology of dual weighted residuals is applied to an optimal control problem for ordinary differential equations. The differential equations are discretized by finite element methods. An a posteriori error estimate is derived and an adaptive algorithm is formulated. The algorithm is implemented in Matlab and tested on a simple model problem from vehicle dynamics
Square Functions for Ritt Operators in
is a Ritt operator in if . From
\cite{LeMX-Vq}, if is a positive contraction and a Ritt operator in ,
, the square function
is bounded. We
show that if is a Ritt operator in , is bounded when ,
and examine related questions on variational and oscillation norms
Experiments and calibration of a bond-slip relation and efficiency factors for textile reinforcement in concrete
Textile reinforcement yarns consist of many filaments, which can slip relative each other. At modelling of the global structural behaviour, interfilament slip in the yarns, and slip between the yarns and the concrete can be considered by efficiency factors for the stiffness and strength of the yarns, and by applying a bond-slip relation between yarns and concrete. In this work, an effective and robust method for calibration of such models was developed. Two-sided asymmetrical pull-out tests were carried out, with varying embedment lengths designed to obtain both pull-out and rupture of the textile as failure mode. The efficiency factors for strength and stiffness of the textile were very similar, 34% and 35% respectively. This indicates the stress distribution within a yarn to be uneven in a similar manner for small and large stress levels, and that interfilament slip has a larger influence than variation of filamentsâ strength
e-Government for all â Norm-critical Perspectives and Public Values in Digitalization
There are hopes that e-government will bring many benefits, including efficiency, democratization, participation, and emancipation of citizens. However, despite some evidence that supports these claims there are also cases that digitalization can exclude citizens and build new barriers. This is a special challenge for already disadvantaged groups falling outside the norms. In this study we approach the notion of a norm-critical perspective in relation to e-government through a review of literature in combination with action research oriented workshops. From this we conclude that there is a need for more norm-critical perspectives in research on e-government, as most research today focuses on socio-economic digital-divide issues. We also show that it is difficult for involved actors to see beyond the norms and be norm-critical since the norms are embedded into the practices, which in this case, e-government has developed and used
Attityder betrÀffande bevarande i tvÄ olika vildmarksomrÄden i Kenya
All over the world, scientists agree that to succeed with a conservation project, it is important to have a good relationship with the local people. If they do not receive a good impression of the project, they will not be willing to collaborate and the project will probably fail.
According to previous studies, there are different factors affecting attitudes to conservation, like the level of education of the participant. Many studies have shown that the higher education the people have, the more positive attitude they have to adjacent conservation areas. Economical factors are also important, it is often stated that having more money results in a better attitude. The source of the income also has an effect. Those who earn money from conservation are more positive than those who earn money from other sources. Age and gender also affect the attitudes.
In this study the attitudes of local people in two different areas in Kenya was examined. There are conservation work going on in both areas but they area managed in different ways. In the study a group of employees was also included, who all worked with conservation in one of the two areas.
In general the results agreed with the literature and the participant thought that the adjacent conservation area worked well and fulfilled its purpose. As expected was the group with the employees most positive towards conservation. There was also a big difference in attitudes between those who had an income from the conservation area and/or an education and those who had neither. Having both income and education gave the most positive attitude.
This study indicates that education is a very important part in conserving animals and plants. At the same time it is also very important that the local people can receive their rightful part of the benefits and income that conservation can generate
Omplacering av hundar
I the year of 2008 there were more than 60 000 purebred dogs newly registered in the
Swedish Kennel Club. In addition there are a lot of mixed breed dogs and in the year of
2006 it was estimated that there were over 700 000 dogs in Sweden. In todayâs society it is
not unusual that people change their life situation by moving, getting a new job or starting
a family. Because of this there is a risk of rehoming for dogs owned by these people.
In Sweden dogs are among others rehomed by advertising or by rehoming organisations. A
study of research was done to see how a dog is affected by being rehomed and being in a
shelter for rehoming. Research about Swedish rehoming organisations or shelters does not
exist and because of this interviews were done with some of these. The organisations that
were interviewed worked in different ways. Some had their own shelters, some had the
dogs in temporary homes or they just mediated contact information between sellers and
buyers.
One of the big questions before this study started was if it is possible to see any patterns in
which dogs that people want to rehome and why. This was done partly by asking what the
organisations thought and by analysing data that was collected from advertisements which
were found on www.blocket.se during the month of January. The results of the
advertisements were among others that there was no difference in gender of the dogs
(p=0,165), that purebred dogs were more common than mixed breeds (p<0,001) and that
there were more dogs between six months and two years of age than younger than six
months and over two years of age. Other results from the advertisements shown in this
paper are which breeds, and those breeds in mixed breed dogs that were most common and
what reasons people report for rehoming their dog
Lammproduktion pÄ nio ekologiska gÄrdar i vÀstra Sverige
The purpose with this study was to analyze the possibilities to produce organic lambs and to hihglight the most common difficulties in such a production system. A description of current organic and conventional lamb production systems was conducted, both from Sweden and from some other countries.
The Department of Animal Environment and Health at SLU in Skara performed the project together with The County Board of Agriculture in VÀstra Götaland and VÀrmland and The Swedish Animal Health Service. The project lasted from 2002 to 2004. The student report contains the years 2002 and 2003.
In the year of 2003 there were 210 000 adult sheep in Sweden, of which 16 400 adult sheep were certified by KRAV. Of the different countries in Sweden, VÀstra Götaland and Gotland had the largest number of sheep, 14 and 13 per cent of the total number. The total number and the number of certified sheep has increased whereas the total number and number of certified sheep producers have decreased during the last few years. In the year of 2003, the average herd size was 27,7 adult sheep while the average certified herd size was 57,6 adult sheep.
Feeding strategies in organic and conventional lamb productions are quite similar to each
ther. Legumes in mixture with grasses are used as forages in organic production because of
the ability of legumes to fixate nitrogen. According to the rules of KRAV, a maximum of 40
per cent of the daily intake of dry matter can be provided as concentrate. However, during the first three months of lactation the maximum amount of concentrate in the ration is 50 per cent. Lambs are normally weaned when they are three months old, which means that the ewe can be fed with 50 % per cent of concentrate during their whole lactation. Hexane extracted feeds (meal) are prohibited to use as a source of protein in organic production. The feeding ration must thereby be completed by protein feed that are approved by KRAV, such as rapeseed, peas, field beans and lupine.
Intestinal parasites occur in lungs, abomasum, gut and liver in sheep. Parasite infections are mostly a problem for the lambs, ewes has normally developed immunity. However, the
barbers' worm can cause sickness in ewes, especially during lambing or at other times when
the ewe's condition is low. The ewe's immunity does not, however, mean that they're free
om parasites. They can carry parasites that through their manure pass on to the pasture
where they can affect the lambs. By letting different animals, for example cattle and sheep, graze the same pasture simultaneously or by using rotational grazing the risks for parasite infections can be decreased. Parasites are in most cases specific to one species.
Nine farms in western Sweden participated in the study. The herd size varied between 30 and 140 ewes. The breeds were mostly crosses with Fine wool or Texel but also pure bred
Gotlandsheep was used. The farms used different lambing seasons. The ewes were lambing
from January until May and in September. Five of the herds had the ewes lambing in the
winter, three in the spring, two in the summer and two in the autumn. The farms were visited five times a year during the project. Lambing time, number of lambs per ewe, lamb weights and lamb age at weaning were registered. Slaughter data were collected from the abbatoir. Results from 2002 and 2003 are shown as birth weight, weight at 110 days of age, age at slaughter, body conformation and fat content of the carcass.
Parasite status in the herds and methods that were used to reduce the risks for parasite infections were studied. The frequency of parasites where registered with assistance from the Swedish Animal Health Association. Several farms let the sheep graze together with cattle or horses and/or rotate sheep and cattle for grazing. Despite this, six of the farms had sheep affected by the barbers' worm. Intestinal parasites are thereby a large problem in organic lamb production. To reduce the risks for infections that cause production losses it is important to take faecal samples from the ewes before the grazing period to find out the status of parasites in the herd. Except for the barbers worm, there also were some problems with lung worm, large liver fluke and giardia. It is important to have control over the lambs and weigh them once in a while during the grazing period. By weighing the lambs you can discover if the growth rate of the lambs has been reduced, which can be a sign of a parasite infection.
In the last years, forages that contain condensed tannins, for example birdsfoot trefoil, been noticed as feed for ruminants. Condensed tannins reduce the risk for parasite infections. However, studies at RöbÀcksdalen, The Swedish University of Agricultural Sciences, UmeÄ, have not shown any effects of tannins on prevalence of parasite infections under Swedish conditions.
Feeding rations for lactating ewes in 2003 were made for five herds in the study. The feeding rations were based on nutrient analyses of the forages and concentrates. Random bales of thilage that were used as feed were weighed to estimate the amount of silage offered to the animals. Feeding rations were compared to the nutrient requirements of lactating ewes. It was shown that the ewes on most of the farms had sufficient provisions of protein and energy. The most common concentrates were grain mixtures combined with a protein mixture.
Today lambs are produced almost the whole year round. What production model that should be used should be based on the condition of the farm. In a production system with lambs born in the winter the lambs are raised intensively and the aim is to have them slaughtered before the grazing period starts. The ewes can then be used as nature conservators on semi-natural grasslands. Large amounts of pasture, both for ewes and lambs are needed, in a production model with spring born lambs. In a production system with summer born lambs the ewes can e grazing semi-natural grasslands in spring whereas they during summer and autumn during their late pregnancy and lactation have a demand for a high quality pasture. A production witlambs born in the autumn is based on the idea to let ewes graze regrowth pastures in the autumn during late pregnancy and lactation. After the grazing period the aim is to feed ewes and lambs with forages (silage) only. The lambs are raised extensively and are slaughtered inthe spring.
Carcasses of lambs are judged after weight, form and content of fat in the body. The form is judged according to the five main classes of the EUROP-system, E, U, R, O and P that is omplemented with + and -. The content of fat is judged in the same way, with 1, 2, 3, 4 and 5 and is complemented with + and -. The requirements to receive the extra KRAV supplement were in 2002 and 2003 a conformation class from E+ to O, fat content of 2-to 3 and a slaughter weight between 14 and 25,9 kg.
In this study, results form lambs born 2002 and 2003 were presented. The results were presented separately for ewe and ram lambs, winter born, spring born and autumn born. Lambs that were born in autumn were only few in the study and it is hard to make any conclusions for that kind of production model. However, it is an interesting model that needs to be studied more extensively. To compare how the growth rate differed among farms growth rate was calculated from birth weight, slaughter weight and an expected dressing percentage oft 40 per cent. The daily growth rate varied between 145 and 339 g. The large difference is caused by the conditions on the farms and the aim of the production model. Low daily growth rates are also certainly caused by parasite infections.
There are great opportunities to succeed with organic as well as conventional lamb production. The largest problem with lamb production is parasite infections of the lambs, even when methods have been used to reduce the risks for infections. You have to control the parasite status of the lambs by weighing and by taking faecal samples during the grazing periods. When choosing a model you should take into account the conditions of the farm including types of buildings and pastures.Syftet med studien var att undersöka möjligheterna att bedriva ekologisk lammproduktion samt var de största svÄrigheterna i en sÄdan produktion fanns. Nio gÄrdar i vÀstra Sverige deltog i dokumentationen. En nulÀgesbeskrivning av lammproduktion, bÄde konventionell och ekologisk, i Sverige och i nÄgra andra lÀnder genomfördes.
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r 2003 fanns 210 000 vuxna fĂ„r i Sverige, varav 16 400 vuxna fĂ„r var anslutna till KRAV. Av de olika lĂ€nen var det VĂ€stra Götaland och Gotland som hade flest fĂ„r, 14 respektive 13 % av det totala antalet i landet. Det totala antalet och KRAV-godkĂ€nda fĂ„r har under senare Ă„r ökat medan det totala antalet och antalet KRAV-godkĂ€nda företag med fĂ„r minskat. Ă
r 2003 hade medelbesÀttningen 27,7 vuxna fÄr medan den KRAV-anslutna medelbesÀttningen hade 57,6 vuxna djur.
Utfodring inom ekologisk lammproduktion skiljer sig inte sÄ mycket frÄn den konventionella. I ekologisk produktion utnyttjar man luftens kvÀve genom att ha ett stort baljvÀxtinslag i vallen. Till tackor fÄr högst 40 % av det dagliga torrsubstansintaget i foderstaten utgöras av kraftfoder enligt KRAVs regler. Under de tre första mÄnaderna under digivningen fÄr kraftfoderandelen höjas till 50 %. Lamm avvÀnjs vanligtvis vid tre mÄnaders Älder vilket betyder att tackan under hela digivningen kan utfodras med 50 % kraftfoder. Numera fÄr inte hexanextraherade fodermedel anvÀndas som proteinkÀlla i ekologisk produktion, vilket gör att mÄnga proteinfodermedel inte kan anvÀndas. DÀrför mÄste kravgodkÀnda kraftfodermedel sÄsom raps, Àrter, Äkerböna eller lupin anvÀndas.
InÀlvsparasiter hos fÄr förekommer i lungor, löpmage, tarm och lever. Parasitangrepp Àr frÀmst ett problem hos lammen dÄ tackor i regel utvecklat immunitet. Stora magmasken Àr dock ett undantag, dÄ den Àven kan orsaka sjukdom hos tackor i samband med lamning eller under annan tidpunkt dÄ de Àr i sÀmre kondition. DÄ tackorna Àr immuna betyder det inte att de Àr parasitfria. De kan bÀra pÄ parasiter som via trÀcken kommer ut pÄ betet och sedan angriper lammen. Genom sambete och vÀxelbete med andra djurslag kan man minska riskerna för parasitangrepp. Parasiterna Àr i de flesta fall artspecifika, d v s angriper ett djurslag. Genom att de olika djurslagen betar varandras rator betar de varandras parasiter.
Nio gÄrdar belÀgna i vÀstra Sverige ingick i studien. BesÀttningsstorleken var mellan 30- 140 tackor vardera. Raserna var mestadels korningar med finull eller texel samt renrasiga gotlandsfÄr. Olika lamningstidpunkter tillÀmpades pÄ gÄrdarna. Tackorna lammade frÄn januari till maj samt i september. Fem av gÄrdarna hade vinterlammande tackor, tre vÄrlammande, tvÄ sommarlammande och tvÄ höstlammande. De resultat som redovisas för tvÄ Är Àr lammens födelsevikt, vikt vid 110-dagars Älder, Älder vid slakt, slaktvikt, formklass, fettklass samt hur stor andel av lammen som klarade grÀnsen för mÀrkeskvalitet.
Utöver slaktresultaten studerades Àven hur parasitstatusen sÄg ut pÄ gÄrdarna och vad som gjordes för att minska risken för parasitangrepp. PÄ flertalet av gÄrdarna i studien tillÀmpades sambete och/eller vÀxelbete med nötkreatur och/eller hÀstar. Trots detta var det pÄ sex av gÄrdarna som fÄren fick angrepp av stora magmasken. InÀlvsparasiter Àr sÄledes ett stort problem inom ekologisk lammproduktion. För att motverka risken för parasitangrepp med pÄföljande produktionsförluster Àr det dÀrför viktigt att ta trÀckprov pÄ tackor innan betesslÀppning för att ta reda pÄ parasitstatusen i besÀttningen. Förutom stora magmasken förekom Àven enstaka problem med lungmask, stora leverflundran och giardia. Det Àr Àven viktigt att ha lammen under uppsikt och vÀga dem kontinuerligt under betessÀsongen. Genom att vÀga lammen kan man tidigt upptÀcka om tillvÀxten avtagit, dÄ detta kan vara tecken pÄ parasitangrepp.
PÄ senare Är har vÀxter innehÄllande kondenserade tanniner, exempelvis kÀringtand, uppmÀrksammats som fodervÀxt. Kondenserade tanniner sÀgs minska risken för parasitangrepp. Studier vid RöbÀcksdalen har dock inte gett nÄgra resultat som visar att det gÀller under svenska förhÄllanden.
För fem av gÄrdarna i projektet berÀknades en foderstat till tackorna under digivningen 2003. Foderstaten baserades pÄ analyser av vall- och kraftfoder samt angiven kraftfodergiva frÄn lantbrukarna och stickprovsvÀgning av rundbalsensilaget som utfodrades. Foderstaterna jÀmfördes sedan med normen för digivande tackors nÀringsbehov. PÄ de flesta gÄrdarna visade det sig att tackorna nÀringsförsörjde sig tÀmligen vÀl betrÀffande energi- och protein. Vanligaste kraftfodret var spannmÄlsblandning i kombination med nÄgon proteinmix.
Lamm produceras i stort sett under hela Äret. GÄrdens förutsÀttningar bör avgöra vilken produktionsmodell som vÀljs. Vid vinterlamning föds lammen upp intensivt och mÄlsÀttningen Àr att de skall slaktas före betesslÀppning. Tackor utan lamm kan dÄ med fördel beta naturbetesmark. Produktion av vÄrlamm krÀver stora betesarealer för bÄde tackor och lamm. Vid sommarlamning kan tackor beta naturbeten under vÄren, medan de under resterande del av betesperioden krÀver ett nÀringsrikt Äkermarksbete. Vid höstlamning fÄr tackorna beta ÄtevÀxtbete under hösten. Efter installning utfodras enbart grovfoder till bÄde tackor och lamm. Lammen föds dÄ upp mer extensivt och gÄr till slakt under vÄren.
Vid slakt bedöms lammens slaktkropp efter vikt, formklass och fettansÀttning. Formen bedöms enligt EUROP-systemets fem huvudklasser, E, U, R, O och P som kompletteras med + och -. Slaktkroppens fettinnehÄll bedöms pÄ liknande sÀtt med klasserna 1, 2, 3, 4 och 5 som kompletteras med + och -. KvalitetsgrÀnserna för att erhÄlla KRAV-tillÀgget var mellan Är 2002 och 2004 formklass E+ till O, fettgrupp 2- till 3 och en slaktvikt mellan 14-25,9 kg. I studien bearbetades slaktresultaten för lamm födda Är 2002 och 2003. Resultaten Àr uppdelade för bagglamm respektive tacklamm samt vinterfödda, vÄrfödda respektive höstfödda lamm. DÄ antalet höstfödda lamm i studien var relativt fÄ Àr det svÄrt att dra nÄgra slutsatser av den produktionsformen Det Àr dock en intressant uppfödningsmodell dÀr mer studier skulle behövas. För att jÀmföra hur tillvÀxten skiljde sig mellan de olika gÄrdarna berÀknades tillvÀxten frÄn födsel till slakt fram med hjÀlp av födelsevikt, slaktvikt och ett uppskattat slaktutbyte pÄ 40 %. Den dagliga tillvÀxten varierade mellan 145 och 339 g. Den stora skillnaden i tillvÀxt beror pÄ gÄrdens förutsÀttningar och vilket mÄl med produktionen besÀttningarna hade. LÄg tillvÀxt beror sÀkerligen Àven pÄ parasitangrepp.
FörutsÀttningar finns att lyckas lika bra med ekologisk som med konventionell lammproduktion. Vad som kan stÀlla till problem Àr att lammen i vissa fall kan drabbas av parasitinfektion trots att ÄtgÀrder vidtagits för att förhindra detta. Man mÄste vara uppmÀrksam pÄ lammens parasitstatus genom regelbunden vÀgning av lammen och trÀckprovstagning under betessÀsongen. Vid valet av produktionsmodell bör man utgÄ frÄn gÄrdens förutsÀttningar, vilken typ av byggnader som finns samt vilken sorts beten man har
Relativesâ participation in everyday care in special care units for persons with dementia
Background: Research concerning relativesâ participation in the everyday care related to persons living in special care units for persons with dementia is limited.
Research questions: To examine relativesâ participation in their near oneâs everyday care, the level of burden experienced and important factors for participation, in this special context.
Design: The study had a cross-sectional design, and data collection was carried out by means of a study-specific questionnaire.
Participants and context: A total of 233 relatives from 23 different special care units participated.
Ethical consideration: The study was approved by the Norwegian Social Science Data Services.
Results: A great majority of relatives reported that they visited weekly and were the residentâs spokesperson, but seldom really participated in decisions concerning their everyday care. Participation was seldom reported as a burden.
Discussion: This study indicated that relatives were able to make a difference to their near oneâs everyday life and ensure quality of care based on their biographical expertise, intimate knowledge about and emotional bond with the resident. Since knowing the resident is a prerequisite for providing individualised care that is in line with the residentâs preferences, information concerning these issues is of utmost importance.
Conclusion: This study prompts reflection about what it is to be a spokesperson and whether everyday care is neglected in this role. Even though relatives were satisfied with the care provided, half of them perceived their participation as crucial for the residentâs well-being. This indicated that relatives were able to offer important extras due to their biographical expertise, intimate knowledge about and emotional bond with the resident. Good routines securing that written information about the residentsâ life history and preferences is available and used should be implemented in practice
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