The role of lakes in carbon cycling in boreal catchments

Lakes are an important component of ecosystem carbon cycle through both organic carbon sequestration and carbon dioxide and methane emissions, although they cover only a small fraction of the Earth's surface area. Lake sediments are considered to be one of rather perma-nent sinks of carbon in boreal regions and furthermore, freshwater ecosystems process large amounts of carbon originating from terrestrial sources. These carbon fluxes are highly uncer-tain especially in the changing climate. -- The present study provides a large-scale view on carbon sources and fluxes in boreal lakes situated in different landscapes. We present carbon concentrations in water, pools in lake se-diments, and carbon gas (CO2 and CH4) fluxes from lakes. The study is based on spatially extensive and randomly selected Nordic Lake Survey (NLS) database with 874 lakes. The large database allows the identification of the various factors (lake size, climate, and catchment land use) determining lake water carbon concentrations, pools and gas fluxes in different types of lakes along a latitudinal gradient from 60oN to 69oN. Lakes in different landscapes vary in their carbon quantity and quality. Carbon (C) content (total organic and inorganic carbon) in lakes is highest in agriculture and peatland dominated areas. In peatland rich areas organic carbon dominated in lakes but in agricultural areas both organic and inorganic C concentrations were high. Total inorganic carbon in the lake water was strongly dependent on the bedrock and soil quality in the catchment, especially in areas where human influence in the catchment is low. In inhabited areas both agriculture and habitation in the catchment increase lake TIC concentrations, since in the disturbed soils both weathering and leaching are presumably more efficient than in pristine areas. TOC concentrations in lakes were related to either catchment sources, mainly peatlands, or to retention in the upper watercourses. Retention as a regulator of the TOC concentrations dominated in southern Finland, whereas the peatland sources were important in northern Finland. The homogeneous land use in the north and the restricted catchment sources of TOC contribute to the close relationship between peatlands and the TOC concentrations in the northern lakes. In southern Finland the more favorable climate for degradation and the multiple sources of TOC in the mixed land use highlight the importance of retention. Carbon processing was intensive in the small lakes. Both CO2 emission and the Holocene C pool in sediments per square meter of the lake area were highest in the smallest lakes. How-ever, because the total area of the small lakes on the areal level is limited, the large lakes are important units in C processing in the landscape. Both CO2 and CH4 concentrations and emissions were high in eutrophic lakes. High availability of nutrients and the fresh organic matter enhance degradation in these lakes. Eutrophic lakes are often small and shallow, enabling high contact between the water column and the sediment. At the landscape level, the lakes in agricultural areas are often eutrophic due to fertile soils and fertilization of the catchments, and therefore they also showed the highest CO2 and CH4 concentrations. Export from the catchments and in-lake degradation were suggested to be equally important sources of CO2 and CH4 in fall when the lake water column was intensively mixed and the transport of sub-stances from the catchment was high due to the rainy season. In the stagnant periods, especially in the winter, in-lake degradation as a gas source was highlighted due to minimal mixing and limited transport of C from the catchment. The strong relationship between the annual CO2 level of lakes and the annual precipitation suggests that climate change can have a major impact on C cycling in the catchments. Increase in precipitation enhances DOC export from the catchments and leads to increasing greenhouse gas emissions from lakes. The total annual CO2 emission from Finnish lakes was estimated to be 1400 Gg C a-1. The total lake sediment C pool in Finland was estimated to be 0.62 Pg, giving an annual sink in Finnish lakes of 65 Gg C a-1.

Preoperative visual acuity of cataract patients. Repeatability of visual acuity and refractive error measurements in clinical settings

Visual acuities at the time of referral and on the day before surgery were compared in 124 patients operated on for cataract in Vaasa Central Hospital, Finland. Preoperative visual acuity and the occurrence of ocular and general disease were compared in samples of consecutive cataract extractions performed in 1982, 1985, 1990, 1995 and 2000 in two hospitals in the Vaasa region in Finland. The repeatability and standard deviation of random measurement error in visual acuity and refractive error determination in a clinical environment in cataractous, pseudophakic and healthy eyes were estimated by re-examining visual acuity and refractive error of patients referred to cataract surgery or consultation by ophthalmic professionals. Altogether 99 eyes of 99 persons (41 cataractous, 36 pseudophakic and 22 healthy eyes) with a visual acuity range of Snellen 0.3 to 1.3 (0.52 to -0.11 logMAR) were examined. During an average waiting time of 13 months, visual acuity in the study eye decreased from 0.68 logMAR to 0.96 logMAR (from 0.2 to 0.1 in Snellen decimal values). The average decrease in vision was 0.27 logMAR per year. In the fastest quartile, visual acuity change per year was 0.75 logMAR, and in the second fastest 0.29 logMAR, the third and fourth quartiles were virtually unaffected. From 1982 to 2000, the incidence of cataract surgery increased from 1.0 to 7.2 operations per 1000 inhabitants per year in the Vaasa region. The average preoperative visual acuity in the operated eye increased by 0.85 logMAR (in decimal values from 0.03to 0.2) and in the better eye 0.27 logMAR (in decimal values from 0.23 to 0.43) over this period. The proportion of patients profoundly visually handicapped (VA in the better eye <0.1) before the operation fell from 15% to 4%, and that of patients less profoundly visually handicapped (VA in the better eye 0.1 to <0.3) from 47% to 15%. The repeatability visual acuity measurement estimated as a coefficient of repeatability for all 99 eyes was ±0.18 logMAR, and the standard deviation of measurement error was 0.06 logMAR. Eyes with the lowest visual acuity (0.3-0.45) had the largest variability, the coefficient of repeatability values being ±0.24 logMAR and eyes with a visual acuity of 0.7 or better had the smallest, ±0.12 logMAR. The repeatability of refractive error measurement was studied in the same patient material as the repeatability of visual acuity. Differences between measurements 1 and 2 were calculated as three-dimensional vector values and spherical equivalents and expressed by coefficients of repeatability. Coefficients of repeatability for all eyes for vertical, torsional and horisontal vectors were ±0.74D, ±0.34D and ±0.93D, respectively, and for spherical equivalent for all eyes ±0.74D. Eyes with lower visual acuity (0.3-0.45) had larger variability in vector and spherical equivalent values (±1.14), but the difference between visual acuity groups was not statistically significant. The difference in the mean defocus equivalent between measurements 1 and 2 was, however, significantly greater in the lower visual acuity group. If a change of ±0.5D (measured in defocus equivalents) is accepted as a basis for change of spectacles for eyes with good vision, the basis for eyes in the visual acuity range of 0.3 - 0.65 would be ±1D. Differences in repeated visual acuity measurements are partly explained by errors in refractive error measurements.

Reduced visual function and its association with physical functioning in the Finnish adult population : Prevalence, causes, and need for eye care services

The purpose of this study was to estimate the prevalence and distribution of reduced visual acuity, major chronic eye diseases, and subsequent need for eye care services in the Finnish adult population comprising persons aged 30 years and older. In addition, we analyzed the effect of decreased vision on functioning and need for assistance using the World Health Organization’s (WHO) International Classification of Functioning, Disability, and Health (ICF) as a framework. The study was based on the Health 2000 health examination survey, a nationally representative population-based comprehensive survey of health and functional capacity carried out in 2000 to 2001 in Finland. The study sample representing the Finnish population aged 30 years and older was drawn by a two-stage stratified cluster sampling. The Health 2000 survey included a home interview and a comprehensive health examination conducted at a nearby screening center. If the invited participants did not attend, an abridged examination was conducted at home or in an institution. Based on our finding in participants, the great majority (96%) of Finnish adults had at least moderate visual acuity (VA ≥ 0.5) with current refraction correction, if any. However, in the age group 75–84 years the prevalence decreased to 81%, and after 85 years to 46%. In the population aged 30 years and older, the prevalence of habitual visual impairment (VA ≤ 0.25) was 1.6%, and 0.5% were blind (VA < 0.1). The prevalence of visual impairment increased significantly with age (p < 0.001), and after the age of 65 years the increase was sharp. Visual impairment was equally common for both sexes (OR 1.20, 95% CI 0.82 – 1.74). Based on self-reported and/or register-based data, the estimated total prevalences of cataract, glaucoma, age-related maculopathy (ARM), and diabetic retinopathy (DR) in the study population were 10%, 5%, 4%, and 1%, respectively. The prevalence of all of these chronic eye diseases increased with age (p < 0.001). Cataract and glaucoma were more common in women than in men (OR 1.55, 95% CI 1.26 – 1.91 and OR 1.57, 95% CI 1.24 – 1.98, respectively). The most prevalent eye diseases in people with visual impairment (VA ≤ 0.25) were ARM (37%), unoperated cataract (27%), glaucoma (22%), and DR (7%). One-half (58%) of visually impaired people had had a vision examination during the past five years, and 79% had received some vision rehabilitation services, mainly in the form of spectacles (70%). Only one-third (31%) had received formal low vision rehabilitation (i.e., fitting of low vision aids, receiving patient education, training for orientation and mobility, training for activities of daily living (ADL), or consultation with a social worker). People with low vision (VA 0.1 – 0.25) were less likely to have received formal low vision rehabilitation, magnifying glasses, or other low vision aids than blind people (VA < 0.1). Furthermore, low cognitive capacity and living in an institution were associated with limited use of vision rehabilitation services. Of the visually impaired living in the community, 71% reported a need for assistance and 24% had an unmet need for assistance in everyday activities. Prevalence of ADL, instrumental activities of daily living (IADL), and mobility increased with decreasing VA (p < 0.001). Visually impaired persons (VA ≤ 0.25) were four times more likely to have ADL disabilities than those with good VA (VA ≥ 0.8) after adjustment for sociodemographic and behavioral factors and chronic conditions (OR 4.36, 95% CI 2.44 – 7.78). Limitations in IADL and measured mobility were five times as likely (OR 4.82, 95% CI 2.38 – 9.76 and OR 5.37, 95% CI 2.44 – 7.78, respectively) and self-reported mobility limitations were three times as likely (OR 3.07, 95% CI 1.67 – 9.63) as in persons with good VA. The high prevalence of age-related eye diseases and subsequent visual impairment in the fastest growing segment of the population will result in a substantial increase in the demand for eye care services in the future. Many of the visually impaired, especially older persons with decreased cognitive capacity or living in an institution, have not had a recent vision examination and lack adequate low vision rehabilitation. This highlights the need for regular evaluation of visual function in the elderly and an active dissemination of information about rehabilitation services. Decreased VA is strongly associated with functional limitations, and even a slight decrease in VA was found to be associated with limited functioning. Thus, continuous efforts are needed to identify and treat eye diseases to maintain patients’ quality of life and to alleviate the social and economic burden of serious eye diseases.

Säilörehun korjuuajan vaikutus maitotilan talouteen –lyhyen aikavälin näkökulma

Tässä tutkimuksessa selvitettiin säilörehun korjuuajan vaikutusta maitotilan talouteen lyhyellä aikavälillä. Tutkimuksessa vertailtiin maitotilan vuosittaisia ylijäämiä neljän eri säilörehun korjuuaikastrategian välillä. Tutkimusongelman ratkaisua varten rakennettiin lineaarinen op-timointimalli, jonka tavoitefunktio oli maitotilan ylijäämän maksimointifunktio. Tarkastelussa oli mukana kaksi vakioitua maitotuotostasoa, 9 000 kg ja 10 000 kg. Työssä käytetyt maidon-tuotantotulokset perustuivat MTT Maaningan Karjatilan kannattava peltoviljely (KARPE) –hankkeessa tehtyihin kolmeen erilliseen ruokintakokeeseen sekä neljään aiempaan ruokinta-kokeeseen, jotka oli selvitetty kirjallisuuden perusteella. Säilörehun satotiedot perustuivat MTT Maaningan ja MTT Siikajoen säilörehukokeisiin. Aikaisin korjattu säilörehu, jonka satojen painotettu D-arvo oli 691 g/kg ka, oli taloudellisesti paras lypsylehmien ruokintavaihtoehto lyhyellä aikavälillä lähtöoletusten vallitessa. Suhteelli-set erot maidontuotannon ylijäämissä säilörehun korjuuaikastrategioiden välillä olivat kuiten-kin hyvin pienet, sillä säilörehun sadot kompensoivat toisiaan määrän ja laadun suhteen. Kol-men niiton säilörehunkorjuu osoittautui selkeästi kalliimmaksi vaihtoehdoksi mm. lisääntynei-den työ- ja konekustannusten takia. Tulokset olivat samansuuntaisia molemmilla maitotuotos-tasoilla. Tämän tutkimuksen perusteella säilörehun korjaaminen suositeltua hieman myöhem-min on lyhyellä aikavälillä lähes yhtä hyvä vaihtoehto kuin suositusten mukainen aikainen korjuu. Korkeaa maitotuotostasoa tavoiteltaessa erittäin myöhään korjatun säilörehun syöttä-minen on kyseenalaista, sillä se vaatisi ruokintaan hyvin korkean väkirehumäärän ja siten al-tistaa lehmän erilaisille sairauksille. Rehuohran hinnan noustessa ylijäämä laski aikaisen niiton strategialla suhteessa enemmän kuin muissa vaihtoehdoissa, kun tilalla oli pinta-alaa käytettävissä vähän. Aikaisessa korjuu-aikastrategiassa maitotilalle jouduttiin ostamaan enemmän viljaa karjan käyttöön kuin muissa strategioissa, joiden pinta-alasta riitti enemmän hehtaareja oman rehuviljan tuotantoon. Tällöin eri korjuuajoilla saavutetut ylijäämät lähenivät toisiaan. Myöhäisellä korjuulla saavutettiin paras ylijäämä, kun rehuohran hinta nousi 1,25-kertaiseksi tai enemmän 9 000 kg:n maito-tuotostasolla. Kolme niittoa osoittautui parhaimmaksi vaihtoehdoksi pienen väkirehuprosentin myötä vasta silloin, kun rehuohran hinta nousi 2,5-kertaiseksi lähtötilanteeseen verrattuna. Säilörehun korjuuaikastrategia on valittava tilakohtaisesti, jolloin koko kasvukauden aikana kertyneet nurmisadot ovat ratkaisevia karjan ruokinnassa. Lyhyellä aikavälillä korjuuajan va-linnalla maitotilan ylijäämään voi vaikuttaa vain vähän. Siksi pitkän aikavälin toimiin säilöre-hun satotasojen parantamiseksi on kiinnitettävä tilatasolla entistä enemmän huomiota.

Äidin hoiva, jaettu vanhemmuus – ja vapaus valita. Perhevapaiden uudistamisen argumentointi 1970-luvulta 2000-luvulle

Tutkimuksessa tarkastellaan perhevapaista Suomessa käytyä poliittista keskustelua ja sen pitkän aikavälin muutosta. Tutkimuksessa syvennytään 1970-luvun uudistusaaltoon, jolloin isät otettiin mukaan järjestelmään, sekä 2000-lukuun, jolloin isiä on eri keinoin kannustettu vapaiden käyttöön. Tässä yhteydessä selvitetään itse uudistusprosesseja, mutta keskei-nen tutkimuskohde ovat päätöksentekoon osallistuneiden toimijoiden perhevapaita koske-vien näkemysten argumentointitavat. Tutkimuksen aineisto koostuu mm. valtiopäiväasia-kirjoista, työryhmämuistioista, hallitusten ja puolueiden ohjelmista ja työmarkkinajärjestöjen kannanotoista. Aineistoa lähestytään kehysanalyysin sekä argumentaatioteorian menetel-mien avulla. Näillä kiinnitetään huomio niihin tekniikoihin, joilla poliittisessa argumentoin-nissa on pyritty saamaan esitetyille toimenpiteille mahdollisimman laaja kannatus. 1970-luvulla keskustelu vanhempainlomista oli hyvin polarisoitunutta. Isien hoivaajaroolin kas-vattaminen oli osa vasemmiston diskurssia, joka pyrki tasa-arvoon niin kodeissa kuin työ-markkinoillakin. Konservatiivien äidinhoivan diskurssi sitä vastoin piti äitiä luonnostaan pa-rempana hoitajana lapselle ja vaati pitkän äitiysloman jatkeeksi kotihoidon tukea, jota va-semmisto puolestaan vastusti. 2000-luvun pääteemoja ovat olleet vanhemmuuden kus-tannusten tasaisempi jakaminen sekä isien kannustaminen vapaiden käyttöön. Isien kan-nustamiseksi on esitetty erilaisia malleja isäkiintiöistä: perusteina ovat olleet muun muassa isä–lapsi-suhde, tasa-arvo sekä Pohjoismaiden positiiviset kokemukset kiintiöistä. Työnan-tajat ja konservatiivit ovat kuitenkin pitäneet kiintiöitä vanhempien valinnanvapauden rajoit-tamisena, vaikka ne muuten ovatkin argumentoineet tasaarvon ja isien kannustamisen puolesta. Isäkiintiöiden kannattajat taas eivät enää 2000-luvulla ole kyseenalaistaneet ko-tihoidon tukea, joka on pidentänyt naisten katkoja työelämästä ja jolla on suuri merkitys lasten hoidon epätasaiselle jakautumiselle.

De "de" : Estudio histórico-comparativo de los usos y la semántica de la preposición "de" en español

El presente estudio supone un intento de describir y analizar el uso de la preposición "de" sobre la base de un corpus diacrónico, con énfasis en las diferentes relaciones semánticas que establece. Partiendo de un total de más de 16.000 casos de "de" hemos establecido 48 categorías de uso, que corresponden a cuatro tipos de construcción sintáctica, a saber, el uso de "de" como complemento de nombres (CN), verbos (CV), adjetivos (CA) y, finalmente, su uso como núcleo de expresiones adverbiales independientes (CI). El estudio consta de tres partes fundamentales. En la parte I, se introduce la Lingüística Cognitiva, que constituye la base teórica esencial del trabajo. Más exactamente, se introducen conceptos como la teoría del prototipo, la teoría de las metáforas conceptuales y la gramática cognitiva, especialmente las ideas de "punto de referencia" y "relación intrínseca" (Langacker 1995, 1999). La parte II incluye el análisis de las 48 categorías. En esta parte se presentan y comentan casi 2.000 ejemplos del uso contextual de "de" extraídos del corpus diacrónico. Los resultados más importantes del análisis pueden resumirse en los siguientes puntos: El uso de "de" sigue siendo esencialmente el mismo en la actualidad que hace 800 años, en el sentido de que todas las 48 categorías se identifican en todas las épocas del corpus. El uso de "de" como complemento nominal va aumentando, al contrario de lo que ocurre con su uso como complemento verbal. En el contexto nominal son especialmente las relaciones posesivas más abstractas las que se hacen más frecuentes, mientras que en el contexto verbal las relaciones que se hacen menos frecuentes son las de separación/alejamiento, causa, agente y partitivo indefinido. Destaca la importancia del siglo XVIII como época de transición entre un primer estado de las cosas y otro posterior, en especial en relación con el carácter cada vez más abstracto de las relaciones posesivas así como con la disminución de las categorías adverbales de causa, agente y partitivo. Pese a la variación en el contexto inmediato de uso, el núcleo semántico de "de" se mantiene inalterado. La parte III toma como punto de partida los resultados del análisis de la parte II, tratando de deslindar el aporte semántico de la preposición "de" a su contexto de uso del valor de la relación en conjunto. Así, recurriendo a la metodología para determinar el significado básico y la metodología para determinar lo que constituyen significados distintos de una preposición (Tyler , Evans 2003a, 2003b), se llega a la hipótesis de que "de" posee cuatro significados básicos, a saber, 'punto de partida', 'tema/asunto', 'parte/todo' y 'posesión'. Esta hipótesis, basada en las metodologías de Tyler y Evans y en los resultados del análisis de corpus, se intenta verificar empíricamente mediante el uso de dos cuestionarios destinados a averiguar hasta qué punto las distinciones semánticas a las que se llega por vía teórica son reconocidas por los hablantes nativos de la lengua (cf. Raukko 2003). El resultado conjunto de los dos acercamientos tanto refuerza como especifica la hipótesis. Los datos que arroja el análisis de los cuestionarios parecen reforzar la idea de que el núcleo semántico de "de" es complejo, constando de los cuatro valores mencionados. Sin embargo, cada uno de estos valores básicos constituye un prototipo local, en torno al cual se construye un complejo de matices semánticos derivados del prototipo. La idea final es que los hablantes son conscientes de los cuatro postulados valores básicos, pero que también distinguen matices más detallados, como son las ideas de 'causa', 'agente', 'instrumento', 'finalidad', 'cualidad', etc. Es decir, "de" constituye un elemento polisémico complejo cuya estructura semántica puede describirse como una semejanza de familia centrada en cuatro valores básicos en torno a los cuales se encuentra una serie de matices más específicos, que también constituyen valores propios de la preposición. Creemos, además, que esta caracterización semántica es válida para todas las épocas de la historia del español, con unas pequeñas modificaciones en el peso relativo de los distintos matices, lo cual está relacionado con la observada variación diacrónica en el uso de "de".