Quantum Tomography with Phase Space Measurements

This thesis addresses the use of covariant phase space observables in quantum tomography. Necessary and sufficient conditions for the informational completeness of covariant phase space observables are proved, and some state reconstruction formulae are derived. Different measurement schemes for measuring phase space observables are considered. Special emphasis is given to the quantum optical eight-port homodyne detection scheme and, in particular, on the effect of non-unit detector efficiencies on the measured observable. It is shown that the informational completeness of the observable does not depend on the efficiencies. As a related problem, the possibility of reconstructing the position and momentum distributions from the marginal statistics of a phase space observable is considered. It is shown that informational completeness for the phase space observable is neither necessary nor sufficient for this procedure. Two methods for determining the distributions from the marginal statistics are presented. Finally, two alternative methods for determining the state are considered. Some of their shortcomings when compared to the phase space method are discussed.

Muukalainen aviovuoteessa : I married a monster for outer space (1958) ja invaasioelokuvan sukupuolittuneet todellisuudet

Teemanumero 1/2011 : Kauhut ja pelot.

Etätoimintojen säästöpotentiaali Lappeenrannan teknillisessä yliopistossa

Työn lähtökohtana oli arvioida etätoimintojen mahdollistamia laskettavissa olevia hyötyjä organisaatiotasolla. Etätyöskentelyn lisäksi työssä tarkasteltavia etätoimintoja ovat tieto- ja viestintätekniikan välityksellä järjestettävät etäkokoukset ja -seminaarit. Työn tavoitteena oli selvittää Lappeenrannan teknillisen yliopiston (LUT) henkilökunnan halukkuus tehdä etätöitä sekä siihen vaikuttavia tekijöitä. Näiden selvittämiseksi toteutettiin etätyöaiheinen kysely henkilökunnalle. Kyselyn tulosten perusteella arvioitiin liikkumisen sekä tilankäytön aiheuttamien kasvihuonekaasupäästöjen sekä kustannusten säästöpotentiaalia LUT:ssa. Lisäksi suoritettiin muutama etätyöaiheinen teemahaastattelu, joiden perusteella pohdittiin etätyöskentelyn käytännön toteutuksessa huomioitavia asioita. Valtaosa LUT:n henkilökunnasta on kiinnostunut etätyömahdollisuudesta. Etätyöskentelyn yleistymiseksi LUT:ssa tulee lisätä tietoa tästä työn organisointitavasta sekä kehittää yhtenäinen toimintatapa etätyöskentelyn käytännön järjestelyihin liittyen. Etätoimintojen hyödyntäminen mahdollistaa LUT:lle organisaationa merkittävien säästöjen saavuttamisen sekä tilatehokkuutta parantamalla, että työmatkustamista vähentämällä. Säästöjä arvioitiin kasvihuonekaasupäästöinä sekä rahana. Etätyöskentelyllä on merkittävä vaikutus myös organisaation työntekijöiden päivittäisten työmatkojen kulkemisen aiheuttamaan kasvihuonekaasupäästömäärään. Etätoimintojen hyödyntämisellä on huomattava potentiaali etenkin liikkumisen aiheuttamien kasvihuonekaasupäästöjen vähentämisessä Suomessa sekä maailmanlaajuisesti hyödynnettynä globaalin ilmastonmuutoksen hillitsemisessä.

Reflexive Space. A Constructionist Model of the Russian Reflexive Marker

This study examines the structure of the Russian Reflexive Marker ( ся/-сь) and offers a usage-based model building on Construction Grammar and a probabilistic view of linguistic structure. Traditionally, reflexive verbs are accounted for relative to non-reflexive verbs. These accounts assume that linguistic structures emerge as pairs. Furthermore, these accounts assume directionality where the semantics and structure of a reflexive verb can be derived from the non-reflexive verb. However, this directionality does not necessarily hold diachronically. Additionally, the semantics and the patterns associated with a particular reflexive verb are not always shared with the non-reflexive verb. Thus, a model is proposed that can accommodate the traditional pairs as well as for the possible deviations without postulating different systems. A random sample of 2000 instances marked with the Reflexive Marker was extracted from the Russian National Corpus and the sample used in this study contains 819 unique reflexive verbs. This study moves away from the traditional pair account and introduces the concept of Neighbor Verb. A neighbor verb exists for a reflexive verb if they share the same phonological form excluding the Reflexive Marker. It is claimed here that the Reflexive Marker constitutes a system in Russian and the relation between the reflexive and neighbor verbs constitutes a cross-paradigmatic relation. Furthermore, the relation between the reflexive and the neighbor verb is argued to be of symbolic connectivity rather than directionality. Effectively, the relation holding between particular instantiations can vary. The theoretical basis of the present study builds on this assumption. Several new variables are examined in order to systematically model variability of this symbolic connectivity, specifically the degree and strength of connectivity between items. In usage-based models, the lexicon does not constitute an unstructured list of items. Instead, items are assumed to be interconnected in a network. This interconnectedness is defined as Neighborhood in this study. Additionally, each verb carves its own niche within the Neighborhood and this interconnectedness is modeled through rhyme verbs constituting the degree of connectivity of a particular verb in the lexicon. The second component of the degree of connectivity concerns the status of a particular verb relative to its rhyme verbs. The connectivity within the neighborhood of a particular verb varies and this variability is quantified by using the Levenshtein distance. The second property of the lexical network is the strength of connectivity between items. Frequency of use has been one of the primary variables in functional linguistics used to probe this. In addition, a new variable called Constructional Entropy is introduced in this study building on information theory. It is a quantification of the amount of information carried by a particular reflexive verb in one or more argument constructions. The results of the lexical connectivity indicate that the reflexive verbs have statistically greater neighborhood distances than the neighbor verbs. This distributional property can be used to motivate the traditional observation that the reflexive verbs tend to have idiosyncratic properties. A set of argument constructions, generalizations over usage patterns, are proposed for the reflexive verbs in this study. In addition to the variables associated with the lexical connectivity, a number of variables proposed in the literature are explored and used as predictors in the model. The second part of this study introduces the use of a machine learning algorithm called Random Forests. The performance of the model indicates that it is capable, up to a degree, of disambiguating the proposed argument construction types of the Russian Reflexive Marker. Additionally, a global ranking of the predictors used in the model is offered. Finally, most construction grammars assume that argument construction form a network structure. A new method is proposed that establishes generalization over the argument constructions referred to as Linking Construction. In sum, this study explores the structural properties of the Russian Reflexive Marker and a new model is set forth that can accommodate both the traditional pairs and potential deviations from it in a principled manner.

Studies of Solar Activity with Emphasis on Quasi-Periodic Oscillations

In this thesis mainly long quasi-periodic solar oscillations in various solar atmospheric structures are discussed, based on data obtained at several wavelengths, focussing, however, mainly on radio frequencies. Sunspot (Articles II and III) and quiet Sun area (QSA) (Article I) oscillations are investigated along with quasi-periodic pulsations (QPP) in a flaring event with wide-range radio spectra (Article IV). Various oscillation periods are detected; 3–15, 35–70 and 90 minutes (QSA), 10-60 and 80-130 minutes (in sunspots at various radio frequencies), 3-5, 10-23, 220-240, 340 and 470 minutes (in sunspots at photosphere) and 8-12 and 15-17 seconds (in a solar flare at radio frequencies). Some of the oscillation periods are detected for the first time, while some of them have been confirmed earlier by other research groups. Solar oscillations can provide more information on the nature of various solar structures. This thesis presents the physical mechanisms of some solar structure oscillations. Two different theoretical approaches are chosen; magnetohydrodynamics (MHD) and the shallow sunspot model. These two theories can explain a wide range of solar oscillations from a few seconds up to some hours. Various wave modes in loop structures cause solar oscillations (<45 minutes) both in sunspots and quiet Sun areas. Periods lasting more than 45 minutes in the sunspots (and a fraction of the shorter periods) are related to sunspot oscillations as a whole. Sometimes similar oscillation periods are detected both in sunspot area variations and respectively in magnetic field strength changes. This result supports a concept that these oscillations are related to sunspot oscillations as a whole. In addition, a theory behind QPPs at radio frequencies in solar flares is presented. The thesis also covers solar instrumentation and data sources. Additionally, the data processing methods are presented. As the majority of the investigations in this thesis focus on radio frequencies, also the most typical radio emission mechanisms are presented. The main structures of the Sun, which are related to solar oscillations, are also presented. Two separate projects are included in this thesis. Solar cyclicity is studied using the extensively large solar radio map archieve from Metsähovi Radio Observatory (MRO) at 37 GHz, between 1978 and 2011 (Article V) covering two full solar cycles. Also, some new solar instrumentation (Article VI) was developed during this thesis.

Plan B from Outer Space - InsomniaGame-pelin suunnittelu ja toteutus 2010–2011

InsomniaGame oli Turun yliopiston digitaalisen kulttuurin oppiaineen ja Insomnia verkkopeliyhdistyksen yhteistyössä vuosina 2010 ja 2011 toteuttama pelikonseptikokeilu. InsomniaGame oli osa laajempaa ”CoEx: Yhteisöllistä tekemistä tukevat tilat kokemusten jakamisessa” kaksivuotista (1.10.2009–31.12.2011) hanketta, jonka toteuttivat yhteistyössä Turun yliopiston Porin yksikkö, Tampereen teknillisen yliopiston Porin yksikkö ja Tampereen yliopisto. Hankkeen tavoitteena oli toteuttaa sosiaalista mediaa, yhteisöllisyyttä ja lisättyä todellisuutta hyödyntäviä virtuaalisia ja julkisia tiloja, joissa käyttäjät voivat jakaa kokemuksia. Tutkimus on luonteeltaan soveltava pro gradu -tutkielma, joka sisältää kaksi vuotta kestäneen ja kaksi pelisovellusta sisältävän työosuuden. InsomniaGame koostui erilaisista pelaajien suorittamista tehtävistä, pelialustasta sekä taustatarinasta. Päätutkimuskysymykset ovat: Mitkä tekijät vaikuttivat pelisuunnitteluprosessiin ja miten? Työ esittelee InsomniaGame-pelin kehityksen. Erityistarkastelussa ovat suunnitteluprosessin ja pelin sisällölliset muutokset sekä niihin vaikuttaneet tekijät. Pelin kehitys perustui pääasiassa erilaisiin dokumentteihin, joita käytettiin suunnittelun apuvälineenä sekä viestinnässä projektin eri toimijoiden kesken. Tutkimus pyrkii syntyneiden dokumenttien sekä pelisuunnittelijoiden muistin perusteella rekonstruoimaan InsomniaGame-pelisovelluksen kehityskaaren. InsomniaGamen kehityksessä oli monia tekijöitä, jotka muuttuivat sen kehityskaaren aikana. Itse pelin sisältö, kuten myös suunnittelutapa, muuttuivat kahden vuoden aikana huomattavasti. Pelillä oli myös monia erityispiirteitä, jotka tekevät sen kehityksestä ainutlaatuisen, sillä esimerkiksi pelin testaaminen yhtenä kokonaisuutena oli mahdotonta. Lisäksi peli oli tutkimus- ja yhteistyöprojekti, jossa oli mukana monia eri toimijoita ja erityisesti tutkimuksessa korostuu yhteistyökumppani Insomnia verkkopeliyhdistyksen osallisuus. InsomniaGamen kummankaan vuoden toteutus ei sujunut odotetulla tavalla, mikä osaltaan vaikutti etenkin jälkimmäisen vuoden pelin suunnitteluun. Varsinainen suunnittelutyö kuitenkin eteni ensimmäisenä vuonna käytetyn mallin mukaisesti, mutta kuitenkin niin että alkuperäiset oletukset pelisuunnittelusta ja lopputuloksesta muuttuivat. Tämän vuoksi peliprojektia voi paikoitellen luonnehtia jopa kaoottiseksi, ja erityisesti toteutusvaiheessa jouduttiin luomaan nopealla aikataululla uusia toimintamalleja. Työ toimii mallina tuleville peliprojekteille, mutta erityisen tärkeää olisi luoda yhtenäinen kehitysalusta vastaavanlaisia projekteja varten.

Lagrangian multipliers for coast-arcs of optimum space trajectories

Some properties of generalized canonical systems - special dynamical systems described by a Hamiltonian function linear in the adjoint variables - are applied in determining the solution of the two-dimensional coast-arc problem in an inverse-square gravity field. A complete closed-form solution for Lagrangian multipliers - adjoint variables - is obtained by means of such properties for elliptic, circular, parabolic and hyperbolic motions. Classic orbital elements are taken as constants of integration of this solution in the case of elliptic, parabolic and hyperbolic motions. For circular motion, a set of nonsingular orbital elements is introduced as constants of integration in order to eliminate the singularity of the solution.

Numerical and experimental investigation of thermal louvers for space applications

Thermal louvers, using movable or rotating shutters over a radiating surface, have gained a wide acceptance as highly efficient devices for controlling the temperature of a spacecraft. This paper presents a detailed analysis of the performance of a rectangular thermal louver with movable blades. The radiative capacity of the louver, determined by its effective emittance, is calculated for different values of the blades opening angle. Experimental results obtained with a prototype of a spacecraft thermal louver show good agreement with the theoretical values.

Design Space Exploration for MPSoC Architectures

Multiprocessor system-on-chip (MPSoC) designs utilize the available technology and communication architectures to meet the requirements of the upcoming applications. In MPSoC, the communication platform is both the key enabler, as well as the key differentiator for realizing efficient MPSoCs. It provides product differentiation to meet a diverse, multi-dimensional set of design constraints, including performance, power, energy, reconfigurability, scalability, cost, reliability and time-to-market. The communication resources of a single interconnection platform cannot be fully utilized by all kind of applications, such as the availability of higher communication bandwidth for computation but not data intensive applications is often unfeasible in the practical implementation. This thesis aims to perform the architecture-level design space exploration towards efficient and scalable resource utilization for MPSoC communication architecture. In order to meet the performance requirements within the design constraints, careful selection of MPSoC communication platform, resource aware partitioning and mapping of the application play important role. To enhance the utilization of communication resources, variety of techniques such as resource sharing, multicast to avoid re-transmission of identical data, and adaptive routing can be used. For implementation, these techniques should be customized according to the platform architecture. To address the resource utilization of MPSoC communication platforms, variety of architectures with different design parameters and performance levels, namely Segmented bus (SegBus), Network-on-Chip (NoC) and Three-Dimensional NoC (3D-NoC), are selected. Average packet latency and power consumption are the evaluation parameters for the proposed techniques. In conventional computing architectures, fault on a component makes the connected fault-free components inoperative. Resource sharing approach can utilize the fault-free components to retain the system performance by reducing the impact of faults. Design space exploration also guides to narrow down the selection of MPSoC architecture, which can meet the performance requirements with design constraints.

Scheduling dynamic dataflow graphs with model checking

With the shift towards many-core computer architectures, dataflow programming has been proposed as one potential solution for producing software that scales to a varying number of processor cores. Programming for parallel architectures is considered difficult as the current popular programming languages are inherently sequential and introducing parallelism is typically up to the programmer. Dataflow, however, is inherently parallel, describing an application as a directed graph, where nodes represent calculations and edges represent a data dependency in form of a queue. These queues are the only allowed communication between the nodes, making the dependencies between the nodes explicit and thereby also the parallelism. Once a node have the su cient inputs available, the node can, independently of any other node, perform calculations, consume inputs, and produce outputs. Data ow models have existed for several decades and have become popular for describing signal processing applications as the graph representation is a very natural representation within this eld. Digital lters are typically described with boxes and arrows also in textbooks. Data ow is also becoming more interesting in other domains, and in principle, any application working on an information stream ts the dataflow paradigm. Such applications are, among others, network protocols, cryptography, and multimedia applications. As an example, the MPEG group standardized a dataflow language called RVC-CAL to be use within reconfigurable video coding. Describing a video coder as a data ow network instead of with conventional programming languages, makes the coder more readable as it describes how the video dataflows through the different coding tools. While dataflow provides an intuitive representation for many applications, it also introduces some new problems that need to be solved in order for data ow to be more widely used. The explicit parallelism of a dataflow program is descriptive and enables an improved utilization of available processing units, however, the independent nodes also implies that some kind of scheduling is required. The need for efficient scheduling becomes even more evident when the number of nodes is larger than the number of processing units and several nodes are running concurrently on one processor core. There exist several data ow models of computation, with different trade-offs between expressiveness and analyzability. These vary from rather restricted but statically schedulable, with minimal scheduling overhead, to dynamic where each ring requires a ring rule to evaluated. The model used in this work, namely RVC-CAL, is a very expressive language, and in the general case it requires dynamic scheduling, however, the strong encapsulation of dataflow nodes enables analysis and the scheduling overhead can be reduced by using quasi-static, or piecewise static, scheduling techniques. The scheduling problem is concerned with nding the few scheduling decisions that must be run-time, while most decisions are pre-calculated. The result is then an, as small as possible, set of static schedules that are dynamically scheduled. To identify these dynamic decisions and to find the concrete schedules, this thesis shows how quasi-static scheduling can be represented as a model checking problem. This involves identifying the relevant information to generate a minimal but complete model to be used for model checking. The model must describe everything that may affect scheduling of the application while omitting everything else in order to avoid state space explosion. This kind of simplification is necessary to make the state space analysis feasible. For the model checker to nd the actual schedules, a set of scheduling strategies are de ned which are able to produce quasi-static schedulers for a wide range of applications. The results of this work show that actor composition with quasi-static scheduling can be used to transform data ow programs to t many different computer architecture with different type and number of cores. This in turn, enables dataflow to provide a more platform independent representation as one application can be fitted to a specific processor architecture without changing the actual program representation. Instead, the program representation is in the context of design space exploration optimized by the development tools to fit the target platform. This work focuses on representing the dataflow scheduling problem as a model checking problem and is implemented as part of a compiler infrastructure. The thesis also presents experimental results as evidence of the usefulness of the approach.

The European Union and Assembling Biofuel Development – topological investigations concerning the associations between law, policy and space

Biofuels for transport are a renewable source of energy that were once heralded as a solution to multiple problems associated with poor urban air quality, the overproduction of agricultural commodities, the energy security of the European Union (EU) and climate change. It was only after the Union had implemented an incentivizing framework of legal and political instruments for the production, trade and consumption of biofuels that the problems of weakening food security, environmental degradation and increasing greenhouse gases through land-use changes began to unfold. In other words, the difference between political aims for why biofuels are promoted and their consequences has grown – which is also recognized by the EU policy-makers. Therefore, the global networks of producing, trading and consuming biofuels may face a complete restructure if the European Commission accomplishes its pursuit to sideline crop-based biofuels after 2020. My aim with this dissertation is not only to trace the manifold evolutions of the instruments used by the Union to govern biofuels but also to reveal how this evolution has influenced the dynamics of biofuel development. Therefore, I study the ways the EU’s legal and political instruments of steering biofuels are coconstitutive with the globalized spaces of biofuel development. My analytical strategy can be outlined through three concepts. I use the term ‘assemblage’ to approach the operations of the loose entity of actors and non-human elements that are the constituents of multi-scalar and -sectorial biofuel development. ‘Topology’ refers to the spatiality of this European biofuel assemblage and its parts whose evolving relations are treated as the active constituents of space, instead of simply being located in space. I apply the concept of ‘nomosphere’ to characterize the framework of policies, laws and other instruments that the EU applies and construes while attempting to govern biofuels. Even though both the materials and methods vary in the independent articles, these three concepts characterize my analytical strategy that allows me to study law, policy and space associated with each other. The results of my examinations underscore the importance of the instruments of governance of the EU constituting and stabilizing the spaces of producing and, on the other hand, how topological ruptures in biofuel development have enforced the need to reform policies. This analysis maps the vast scope of actors that are influenced by the mechanism of EU biofuel governance and, what is more, shows how they are actively engaging in the Union’s institutional policy formulation. By examining the consequences of fast biofuel development that are spatially dislocated from the established spaces of producing, trading and consuming biofuels such as indirect land use changes, I unfold the processes not tackled by the instruments of the EU. Indeed, it is these spatially dislocated processes that have pushed the Commission construing a new type of governing biofuels: transferring the instruments of climate change mitigation to land-use policies. Although efficient in mitigating these dislocated consequences, these instruments have also created peculiar ontological scaffolding for governing biofuels. According to this mode of governance, the spatiality of biofuel development appears to be already determined and the agency that could dampen the negative consequences originating from land-use practices is treated as irrelevant.

Adaptive Markov chain Monte Carlo and Bayesian filtering for state space models

This thesis is concerned with the state and parameter estimation in state space models. The estimation of states and parameters is an important task when mathematical modeling is applied to many different application areas such as the global positioning systems, target tracking, navigation, brain imaging, spread of infectious diseases, biological processes, telecommunications, audio signal processing, stochastic optimal control, machine learning, and physical systems. In Bayesian settings, the estimation of states or parameters amounts to computation of the posterior probability density function. Except for a very restricted number of models, it is impossible to compute this density function in a closed form. Hence, we need approximation methods. A state estimation problem involves estimating the states (latent variables) that are not directly observed in the output of the system. In this thesis, we use the Kalman filter, extended Kalman filter, Gauss–Hermite filters, and particle filters to estimate the states based on available measurements. Among these filters, particle filters are numerical methods for approximating the filtering distributions of non-linear non-Gaussian state space models via Monte Carlo. The performance of a particle filter heavily depends on the chosen importance distribution. For instance, inappropriate choice of the importance distribution can lead to the failure of convergence of the particle filter algorithm. In this thesis, we analyze the theoretical Lᵖ particle filter convergence with general importance distributions, where p ≥2 is an integer. A parameter estimation problem is considered with inferring the model parameters from measurements. For high-dimensional complex models, estimation of parameters can be done by Markov chain Monte Carlo (MCMC) methods. In its operation, the MCMC method requires the unnormalized posterior distribution of the parameters and a proposal distribution. In this thesis, we show how the posterior density function of the parameters of a state space model can be computed by filtering based methods, where the states are integrated out. This type of computation is then applied to estimate parameters of stochastic differential equations. Furthermore, we compute the partial derivatives of the log-posterior density function and use the hybrid Monte Carlo and scaled conjugate gradient methods to infer the parameters of stochastic differential equations. The computational efficiency of MCMC methods is highly depend on the chosen proposal distribution. A commonly used proposal distribution is Gaussian. In this kind of proposal, the covariance matrix must be well tuned. To tune it, adaptive MCMC methods can be used. In this thesis, we propose a new way of updating the covariance matrix using the variational Bayesian adaptive Kalman filter algorithm.

Uniform decrease of alpha-global field power induced by intermittent photic stimulation of healthy subjects

Nineteen-channel EEGs were recorded from the scalp surface of 30 healthy subjects (16 males and 14 females, mean age: 34 years, SD: 11.7 years) at rest and under trains of intermittent photic stimulation (IPS) at rates of 5, 10 and 20 Hz. Digitalized data were submitted to spectral analysis with fast fourier transformation providing the basis for the computation of global field power (GFP). For quantification, GFP values in the frequency ranges of 5, 10 and 20 Hz at rest were divided by the corresponding data obtained under IPS. All subjects showed a photic driving effect at each rate of stimulation. GFP data were normally distributed, whereas ratios from photic driving effect data showed no uniform behavior due to high interindividual variability. Suppression of alpha-power after IPS with 10 Hz was observed in about 70% of the volunteers. In contrast, ratios of alpha-power were unequivocal in all subjects: IPS at 20 Hz always led to a suppression of alpha-power. Dividing alpha-GFP with 20-Hz IPS by alpha-GFP at rest (R = alpha-GFP IPS/alpha-GFPrest) thus resulted in ratios lower than 1. We conclude that ratios from GFP data with 20-Hz IPS may provide a suitable paradigm for further investigations.

Collagens and proteoglycans of the corneal extracellular matrix

The cornea is a curved and transparent structure that provides the initial focusing of a light image into the eye. It consists of a central stroma that constitutes 90% of the corneal depth, covered anteriorly with epithelium and posteriorly with endothelium. Its transparency is the result of the regular spacing of collagen fibers with remarkably uniform diameter and interfibrillar space. Corneal collagen is composed of heterotypic fibrils consisting of type I and type V collagen molecules. The cornea also contains unusually high amounts of type VI collagen, which form microfibrillar structures, FACIT collagens (XII and XIV), and other nonfibrillar collagens (XIII and XVIII). FACIT collagens and other molecules, such as leucine-rich repeat proteoglycans, play important roles in modifying the structure and function of collagen fibrils.Proteoglycans are macromolecules composed of a protein core with covalently linked glycosaminoglycan side chains. Four leucine-rich repeat proteoglycans are present in the extracellular matrix of corneal stroma: decorin, lumican, mimecan and keratocan. The first is a dermatan sulfate proteoglycan, and the other three are keratan sulfate proteoglycans. Experimental evidence indicates that the keratan sulfate proteoglycans are involved in the regulation of collagen fibril diameter, and dermatan sulfate proteoglycan participates in the control of interfibrillar spacing and in the lamellar adhesion properties of corneal collagens. Heparan sulfate proteoglycans are minor components of the cornea, and are synthesized mainly by epithelial cells. The effect of injuries on proteoglycan synthesis is discussed.

Amino acid composition of parturient plasma, the intervillous space of the placenta and the umbilical vein of term newborn infants

The objective of the present study was to determine the levels of amino acids in maternal plasma, placental intervillous space and fetal umbilical vein in order to identify the similarities and differences in amino acid levels in these compartments of 15 term newborns from normal pregnancies and deliveries. All amino acids, except tryptophan, were present in at least 186% higher concentrations in the intervillous space than in maternal venous blood, with the difference being statistically significant. This result contradicted the initial hypothesis of the study that the plasma amino acid levels in the placental intervillous space should be similar to those of maternal plasma. When the maternal venous compartment was compared with the umbilical vein, we observed values 103% higher on the fetal side which is compatible with currently accepted mechanisms of active amino acid transport. Amino acid levels of the placental intervillous space were similar to the values of the umbilical vein except for proline, glycine and aspartic acid, whose levels were significantly higher than fetal umbilical vein levels (average 107% higher). The elevated levels of the intervillous space are compatible with syncytiotrophoblast activity, which maintain high concentrations of free amino acids inside syncytiotrophoblast cells, permitting asymmetric efflux or active transport from the trophoblast cells to the blood in the intervillous space. The plasma amino acid levels in the umbilical vein of term newborns probably may be used as a standard of local normality for clinical studies of amino acid profiles.