Phenology and cover of plant growth forms predict herbivore habitat selection in a high latitude ecosystem.

The spatial and temporal distribution of forage quality is among the most central factors affecting herbivore habitat selection. Yet, for high latitude areas, forage quantity has been found to be more important than quality. Studies on large ungulate foraging patterns are faced with methodological challenges in both assessing animal movements at the scale of forage distribution, and in assessing forage quality with relevant metrics.

Risk-sensitive reproductive allocation: fitness consequences of body mass losses in two contrasting environments.

For long-lived organisms, the fitness value of survival is greater than that of current reproduction. Asymmetric fitness rewards suggest that organisms inhabiting unpredictable environments should adopt a risk-sensitive life history, predicting that it is adaptive to allocate resources to increase their own body reserves at the expense of reproduction. We tested this using data from reindeer populations inhabiting contrasting environments and using winter body mass development as a proxy for the combined effect of winter severity and density dependence.

How spatial variation in areal extent and configuration of labile vegetation states affect the riparian bird community in Arctic tundra.

The Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by large herbivores and growing human activity. Thickets of tall shrubs represent a conspicuous vegetation state in northern and temperate ecosystems, where it serves important ecological functions, including habitat for wildlife. Thickets are however labile, as tall shrubs respond rapidly to both abiotic and biotic environmental drivers.

Ethical challenges in nursing emergency practice.

Aim: The aim of this study is to illuminate nurses' experiences of being in ethically difficult situations in an emergency ward.

Background: Nurses working in emergency practice are frequently faced with ethical issues and challenges in their work. Many studies have been conducted concerning ethical challenges, but no empirical studies related to ethics in emergency wards in Norway have been carried out.

Boomers' prospective needs for senior centers and related services: a survey of persons 50-59.

The future service needs of baby boomers are unclear. A survey addressing work/retirement, family, civic engagement, health, caregiving, leisure, and perceptions of senior services was mailed to 800 addresses randomly selected from a upper Midwestern county voter registration list. The response rate was 28%.

Observational evidence of risk-sensitive reproductive allocation in a long-lived mammal.

Organisms should adopt a risk-sensitive reproductive allocation when summer reproductive allocation competes with survival in the coming winter. This trade off is shown through autumn female body mass, which acts as an insurance against unpredictable winter environmental conditions. We tested this hypothesis on female reindeer in a population that has experienced a time period of dramatic increase in abundance.

Vulnerability of rehabilitated agricultural production systems to invasion by nontarget plant species.

Vast areas of arable land have been retired from crop production and "rehabilitated" to improved system states through landowner incentive programs in the United States (e.g., Conservation and Wetland Reserve Programs), as well as Europe (i.

Experimental evidence of a risk-sensitive reproductive allocation in a long-lived mammal.

When reproduction competes with the amount of resources available for survival during an unpredictable nonbreeding season, individuals should adopt a risk-sensitive regulation of their reproductive allocation. We tested this hypothesis on female reindeer (Rangifer tarandus), which face a trade-off between reproduction and acquisition of body reserves during spring and summer, with autumn body mass functioning as insurance against stochastic winter climatic severity. The study was conducted in a population consisting of two herds: one that received supplementary winter feeding for four years while the other utilized natural pastures.

Epithelium and bacteria in periapical lesions.

Objective: The purpose of this study was to evaluate 50 human periapical lesions for bacteria and epithelium in a case study in dental practice.

Study Design: Specimens were obtained from the extraction of 50 untreated teeth that had lesions attached to their apices. The specimens were histologically evaluated using serial sections.

Apical limit of root canal instrumentation and obturation, part 2. A histological study.

The results of an in vivo histological study involving apical and periapical tissues following root canal therapy after different observation periods demonstrated the most favourable histological conditions when the instrumentation and obturation remained at or short of the apical constriction. This was the case in the presence of vital or necrotic pulps, also when bacteria had penetrated the foramen and were present in the periapical tissues. When the sealer and/or the gutta-percha was extruded into the periapical tissue, the lateral canals and the apical ramifications, there was always a severe inflammatory reaction including a foreign body reaction despite a clinical absence of pain.

Incomplete calcium hydroxide removal from the root canal: a case report.

This case demonstrates failure of root canal treatment of a maxillary central incisor following incomplete mechanical removal of a Ca(OH)2 intracanal dressing and subsequent resorption of the material from the apical portion of the root canal. Retreatment some 4 years later involved the removal of the contents of the root canal and permanent obturation by lateral condensation of cold gutta-percha with a sealer. Follow-up showed complete periradicular bone healing with a lamina dura evident.

Periradicular curettage.

Periradicular curettage is a part of the treatment procedure of periradicular surgery. Its main purpose is to remove pathological periradicular tissues for visibility and accessibility to facilitate the treatment of the apical root canal system, or sometimes for the removal of harmful foreign materials present in the periradicular area. Inflammatory periradicular lesions (granuloma and cysts) are the responses of the periradicular tissues to irritants from the root canal and not from the periradicular area unless medicaments and/or filling materials have been forced through the apical foramina or perforations into the periodontium.

Long-term follow-up on C-shaped mandibular molars.

Three cases of mandibular second molars with C-shaped root canal morphology are described. Two of these molars did not radiographically show the usual anatomic configuration of two separated roots, but rather had a single conical root. Only two root canals orifices were observed in the pulp chamber floor: a mesial-lingual orifice in its normal position and a buccal C-shaped fissure that was continuous from the normal location of the mesiobuccal canal to that of the distal canal.

Tissue reaction to endodontic materials: methods, criteria, assessment, and observations.

The purpose of this study was to develop methods and criteria for the testing of the biocompatibility of endodontic materials. One hundred twenty-one teeth from 12 baboons (Papio anubis) were used to test three sealers: AH26, Kerr pulp canal sealer, and Kloroperka N.O.

Clinical, radiographic, and histologic study of endodontic treatment failures.

One hundred fifty cases of endodontic treatment failures were studied clinically, radiographically, and histologically. Fifty-seven percent of the teeth were asymptomatic. Pain alone and/or associated with swelling was present in 21% of the teeth.

Prevalence of previous endodontic treatment, technical standard and occurrence of periapical lesions in a randomly selected adult, general population.

A random sample of 967 subjects selected from the total population in a Swedish county were examined radiographically regarding prevalence and quality of endodontic treatment and occurrence of periapical lesions. The relationship between the technical standard of endodontic treatment and the occurrence of periapical lesions was also analyzed. Of the selected individuals, 95% attended examination (751 dentate and 169 edentulous individuals).

Root canal dentinal tubule disinfection.

Dentinal tubules of the root canal walls of human teeth were infected in vitro with a known bacterial isolate. The roots were exposed to either calcium hydroxide or iodine potassium-iodide for various periods of time and the viability of microorganisms was determined by incubation of entire root samples in a culture medium. The effects of the two agents on microbial viability were evaluated and compared.

[Pulpal-periapical response to canal medication with Ca(OH)2].

This study consisted of biopsies of teeth and root tips removed after Ca(OH)2 therapy. The teeth were clinically intact or exposed to caries, trauma, and/or iatrogenesis. Following the therapy most of the canal walls were clean, but the canals contained varying amounts of pulp tissues, debris and Ca(OH)2 particles.

Traumatically injured primary incisors: a clinical and histological study.

World-wide epidemiological studies state that from 8 percent to 30 percent of children up to 7 years of age sustain injury to primary incisors, including crown fracture, root fracture, tooth avulsion, and dental displacement, which result in malformation of permanent incisors depending upon their state of development. In this study, traumatized primary incisors were evaluated clinically and radiographically, with the following data recorded: exact or approximate time-interval of traumatic episode(s) and extraction, mobility, color change, sensitivity to percussion/palpation, swelling, sinus tract, caries, crown/root fracture, periodontal/periapical lesions, external/internal root resorption, mineralization, and obturation. Based upon the local damage and developmental age, 138 teeth were extracted, fixed in 10 percent formalin, and processed for histological evaluation according to routine methodology.