Structural Comparison between Sucrose and Trehalose in Aqueous Solution

The two sugar molecules sucrose and trehalose are both considered as stabilizing molecules for the purpose of preserving biological materials during, for example, lyophilization or cryo-preservation. Although these molecules share a similar molecular structure, there are several important differences in their properties when they interact with water, such as differences in solubility, viscosity, and glass transition temperature. In general, trehalose has been shown to be more efficient than other sugar molecules in preserving different biological molecules against stress, and thus by investigating how these two disaccharides differ in their water interaction, it is possible to further understand what makes trehalose special in its stabilizing properties. For this purpose, the structure of aqueous solutions of these disaccharides was studied by using neutron and X-ray diffraction in combination with empirical potential structure refinement (EPSR) modeling. The results show that there are surprisingly few differences in the overall structure of the solutions, although there are indications for that trehalose perturbs the water structure slightly more than sucrose

Feedforward neural networks with ReLU activation functions are linear splines

In this thesis the approximation properties of feedforward articial neural networks with one hidden layer and ReLU activation functions are examined. It is shown that functions of these kind are linear splines and the number of spline knots depend on the number of nodes in the network. In fact an upper bound can be derived for the number of knots. Furthermore, the positioning of the knots depend on the optimization of the adjustable parameters of the network. A numerical example is given where the network models are compared to linear interpolating splines with equidistant positioned knots

The Role of Sugars for Protein Stabilization

The understanding of biomolecular interactions with water and co-solutes can lead to greater knowledge regarding the mechanisms behind biomolecular stabilization. This is highly important for developing technologies aimed to preserve biological materials. Such techniques include cryopreservation of pharmaceuticals or human organ transplants, for example. For these purposes, the disaccharide trehalose has been shown to be an outstanding biomolecular stabilizing agent during cryostorage or storage of desiccated materials.In this thesis, the questions regarding the stabilizing role of trehalose is addressed from several different angles. Structural properties of trehalose in water are studied and are compared to those of a similar sugar molecule, namely sucrose. From these studies it was concluded that there were surprisingly small differences between the interactions of trehalose or sucrose with water. The thermodynamic properties of trehalose--water--protein systems were investigated using DSC, where it was indirectly found that the protein hydration shell was not substituted by trehalose, and that the protein stability did not necessarily couple to the glass transition temperature of the trehalose--protein--water-matrix. The structure and dynamics of such a ternary trehalose--water--protein system was also investigated using neutron diffraction combined with EPSR, and QENS combined with an MD simulation. In these studies, it was primarily found that the trehalose molecules were preferentially excluded from the protein surface, and that the local motions of the protein residues were slowed down via a reduction in the motion of the water molecules at the protein surface. Furthermore, the temperature dependences of relaxation dynamics in this system were measured using dielectric spectroscopy. This study showed that the presence of protein hinder certain local trehalose motions, and that the relatively slow dynamics of the trehalose solvent governs the conformational motions of the protein.The presented results elucidates some fundamental properties of how proteins and trehalose behave and interact, which may benefit the development of new biomolecular protective co-solutes

Stabilization of proteins embedded in sugars and water as studied by dielectric spectroscopy

In many products proteins have become an important component, and the long-term properties of these products are directly dependent on the stability of their proteins. To enhance this stability it has become common to add disaccharides in general, and trehalose in particular. However, the mechanisms by which disaccharides stabilize proteins and other biological materials are still not fully understood, and therefore we have here used broadband dielectric spectroscopy to investigate the stabilizing effect of the disaccharides trehalose and sucrose on myoglobin, with the aim to enhance this understanding in general and to obtain specific insights into why trehalose exhibits extraordinary stabilizing properties. The results show the existence of three or four clearly observed relaxation processes, where the three common relaxations are the local (β) water relaxation below the glass transition temperature (Tg), the structuralα-relaxation of the solvent, observed aboveTg, and an even slower protein relaxation due to large-scale conformational protein motions. For the trehalose containing samples with less than 50 wt% myoglobin a fourth relaxation process was observed due to a β-relaxation of trehalose belowTg. This latter process, which was assigned to intramolecular rotations of the monosaccharide rings in trehalose, could not be detected for high protein concentrations or for the sucrose containing samples. Since sucrose has previously been found to form more intramolecular hydrogen bonds at the present hydration levels, it is likely that this rotation becomes too slow to be observed in the case of sucrose. However, this sugar relaxation has probably less influence on the protein stability belowTg, where the better stabilizing effect of trehalose on proteins can be explained by our observation that trehalose slows down the water relaxation more than sucrose does. Finally, we show that the α-relaxation of the solvent and the large-scale protein motions exhibit similar temperature dependences, which suggests that these protein motions are slaved by the α-relaxation. Furthermore, the α-relaxation of the trehalose solution is slower than for the corresponding sucrose solution, and thereby also the protein motions become slower in the trehalose solution, which explains the more efficient stabilizing effect of trehalose on proteins aboveT

Estimation of mass thickness response of embedded aggregated silica nanospheres from high angle annular dark-field scanning transmission electron micrographs

In this study we investigate the functional behavior of the intensity in high-angle annular dark field (HAADF) scanning transmission electron micrograph (STEM) images. The model material is a silica particle (20 nm) gel at 5 wt%. By assuming that the intensity response is monotonically increasing with increasing mass thickness of silica, an estimate of the functional form is calculated using a maximum likelihood approach. We conclude that a linear functional form of the intensity provides a fair estimate but that a power function is significantly better for estimating the amount of silica in the z-direction. The work adds to the development of quantifying material properties from electron micrographs, especially in the field of tomography methods and three-dimensional quantitative structural characterization from a STEM micrograph. It also provides means for direct three-dimensional quantitative structural characterization from a STEM micrograph

Mätning av stammens tvärsnittsarea med hjälp av klave jämfört med diametermåttband i det praktiska skogsbruket

The two most common ways of measuring the breast height diameter of a tree stem is to use a caliper or a diameter measuring tape. In Sweden there is a tradition of using a caliper when estimating the volume of a forest. From an international perspective the diameter measuring tape is the more common tool. The purpose of the study is to show which of the two methods that differ the least from the correct area. Furthermore, the study compares the results from usage of different types of cross calipering methods to each other. It also compares the differences in results these methods presents when measuring pine and spruce. The study started by analyzing and calculate the correct area from 40 tree trundles of pine and spruce. By comparing the result from the cross caliper measuring and the diameter tape measuring it is showed that the caliper is more precise than the diameter tape. The study also indicates that measurements of spruce in thinning forests differ the most from the correct area

Brottsligheten i Sverige: En statistisk studie ur ett socioekonomiskt perspektiv

Earlier studies in other countries have found that inequity and social economic factors influence crime. We examine if the same influence could be found in Sweden. Through a multiple regression we analyze material from Sweden’s 290 municipalities. The dependent variable is measured through reported acts of violent crime since this reflects the total crime rate better than other possible measurements. Our results show that social economic factors indeed are an important indicator of crime in Sweden. Inequity, income and social benefits all affect the municipalities’ crime rates in economic terms. We also conclude that health and age affect the level of crime through that a high level of poor health and a low average aged population increase the crime rate. In contrast to what is expected municipalities’ with a high proportion of females have a higher crime rate. We argue that the result can be derived to a higher proportion of females in metropolitan areas. Further, immigration and separations shown influence in the model. Municipalities’ with a high proportion of immigrants and a high proportion of children with separated parents have more crimes committed per capita. Based on these results we request measures against crime through social reforms

Tillförlitlighet eller tillfällighet - En studie om aktierekommendationer

Syfte: Undersöka hur stor andel av de aktierekommendationer som utfärdas för svenska aktiebolag som visar sig vara goda råd, ett år efter publiceringsdatum. Vidare analyseras ifall det råder någon specifik skillnad mellan köp- och säljrekommendationer. Metod: Kvantitativ studie med deduktiv ansats. Insamlade aktierekommendationer analyseras för att beräkna en eventuell abnormal avkastning. Resultaten testas genom statistiskt z-test och binärvalsregressionsanalys, för att utreda vilka faktorer som påverkar sannolikheten för att rekommendationen är ett gott råd. Teoretiska perspektiv: Studien utgår från den effektiva marknadshypotesen, CAPM samt tidigare forskning. Empiri: Kvantitativ data har samlats in för att undersöka aktiekurser och aktierekommandationer för aktiebolag noterade på NASDAQ OMX Large Cap och Mid Cap. Slutsats: Det går inte att bevisa att aktierekommendationer är goda råd i mer än hälften av fallen. Avseende köp- och säljrekommendationer påvisades skillnader, där köprekommendationer oftast visade sig vara goda råd, medan säljrekommendationer inte visade sig vara det. Bolag som handlas på Mid Cap är, likt köprekommendationer, även de oftast vara goda råd.Purpose: Examining the proportion of the stock recommendations issued for Swedish limited liability company that turns out to be good advice , a year after the publication date. It also analyzes whether there is any specific difference between buy and sell recommendations. Methodology: Quantitative study with a deductive approach. Collected stock recommendations are analyzed and calculated to examine whether or not they yield a possible abnormal return. The results are tested by a statistical z-test and a binary choice model, to examine which variables that affetct the likelihood of the recommendation being seen as a good advice or not. Theoretical perspective: The study is based on the efficient market hypothesis, CAPM and previous research. Empirical foundation: Quantitative data has been collected to investigate share prices and stock recommendations of companies listed on the NASDAQ OMX Large and Mid Cap. Conclusions: There is no proof that stock recommendations are good advices in more than half of the recommendations. Regarding buy and sell recommendations differences were found, where buy recommendations usually turned out to be good advice, while sell recommendations weren’t. Company listed on Mid Cap are, just like buy recommendations, usually good advice

Motions of water and solutes-Slaving versus plasticization phenomena

It is well-accepted that hydration water is crucial for the structure, dynamics, and function of proteins. However, the exact role of water for the motions and functions of proteins is still debated. Experiments have shown that protein and water dynamics are strongly coupled but with water motions occurring on a considerably faster time scale (the so-called slaving behavior). On the other hand, water also reduces the conformational entropy of proteins and thereby acts as a plasticizer of them. In this work, we analyze the dynamics (using broadband dielectric spectroscopy) of some specific non-biological water solutions in a broad concentration range to elucidate the role of water in the dynamics of the solutes. Our results demonstrate that at low water concentrations (less than 5 wt. %), the plasticization phenomenon prevails for all the materials analyzed. However, at higher water concentrations, two different scenarios can be observed: the slaving phenomenon or plasticization, depending on the solute analyzed. These results generalize the slaving phenomenon to some, but not all, non-biological solutions and allow us to analyze the key factors for observing the slaving behavior in protein solutions as well as to reshaping the slaving concept

A Case–Control Study of Lung Cancer Nested in a Cohort of European Asphalt Workers

BACKGROUND: We conducted a nested case-control study in a cohort of European asphalt workers in which an increase in lung cancer risk has been reported among workers exposed to airborne bitumen fume, although potential bias and confounding were not fully addressed. OBJECTIVE: We investigated the contribution of exposure to bitumen, other occupational agents, and tobacco smoking to the risk of lung cancer among asphalt workers. METHODS: Cases were cohort members in Denmark, Finland, France, Germany, the Netherlands, Norway, and Israel who had died of lung cancer between 1980 and the end of follow-up (2002-2005). Controls were individually matched in a 3:1 ratio to cases on year of birth and country. We derived exposure estimates for bitumen fume and condensate, organic vapor, and polycyclic aromatic hydrocarbons, as well as for asbestos, crystalline silica, diesel motor exhaust, and coal tar. Odds ratios (ORs) were calculated for ever-exposure, duration, average exposure, and cumulative exposure after adjusting for tobacco smoking and exposure to coal tar. RESULTS: A total of 433 cases and 1,253 controls were included in the analysis. The OR was 1.12 [95% confidence interval (CI), 0.84-1.49] for inhalation exposure to bitumen fume and 1.17 (95% CI, 0.88-1.56) for dermal exposure to bitumen condensate. No significant trend was observed between lung cancer risk and duration, average exposure, or cumulative exposure to bitumen fume or condensate. CONCLUSIONS: We found no consistent evidence of an association between indicators of either inhalation or dermal exposure to bitumen and lung cancer risk. A sizable proportion of the excess mortality from lung cancer relative to the general population observed in the earlier cohort phase is likely attributable to high tobacco consumption and possibly to coal tar exposure, whereas other occupational agents do not appear to play an important role