CONSIDERATION OF THE VALIDITY OF THE STATISTICAL CHARACTERISTICS OF pH IN SURFACE WATERS

pH is one of the most important parameters characterizing the state of water systems. The arithmetic mean values of samples are often used when averaging serial pH measurements in water bodies, as is usually done for other characteristics of the state of the natural environment (temperature, salinity, oxygen concentrations, suspended solids, etc.). However, in this case such an operation is illegal, since the addition of logarithms, which by definition are pH, is non-additive. The authors conducted a study to determine the extent to which pH variability in natural objects such an operation would not distort the results. For this, several samples of the pH index were generated in various ranges of its theoretically possible and natural variability. It was established that with pH variability of less than a unit characteristic of marine pH values, the statistical characteristics of the indicator and [H+ ] concentrations differ slightly, and the medians of the samples coincide. It is concluded that with such ranges characteristic of the waters of the oceans, there is no need to recalculate previously obtained results. However, for the estuaries of rivers flowing into tidal seas, as shown by field measurements, the pH variability in the mixing zone of sea and river waters is several times higher. Similar situations may occur when heavy precipitation falls on the water surface, as well as during floods. In these cases, a simple averaging of the pH values will no longer be correct. In such cases, the use of other averaging algorithms and the choice of stable statistical characteristics are required.

Prevalence of Sudden Speechlessness in Critical Care Units

Sudden speechlessness (SS) is commonly experienced by patients admitted to critical care units. Although literature findings document challenges associated with periods of SS, the prevalence is unknown. The purpose of this study is to determine the prevalence and characteristics of adult SS patients in four critical care units at a university-affiliated tertiary care hospital. Data are collected on 9 randomly selected days over a 4-month period. The daily prevalence of SS ranges from 16% to 24% in each unit. Characteristic data collected includes patient age, gender, medical diagnosis related to SS episode, type of speechlessness, days since SS began, and communication strategies in use. Respiratory intubation related to various clinical diagnoses is the main cause for SS. Use of multiple specific strategies to convey needs during SS periods are identified. Follow-up studies to further define the prevalence of SS in settings beyond the critical care environment are recommended.

Pacific Salmon Environmental and Life History Models: Advancing Science for Sustainable Salmon in the Future

<em>Abstract.</em>—We describe and demonstrate the Unit Characteristic Method (UCM) as a means by which measurements of habitat from typical stream surveys can be used to estimate the capacity of a stream to rear juvenile steelhead <em>Oncorhynchus mykiss</em>. Channel unit features of importance include surface area by unit type, depth, substrate, and cover. The influence of a stream’s primary productivity is represented in the method through measures of alkalinity and turbidity. We tested the fit of model predictions to juvenile steelhead production observed in seven watersheds ranging in size from 26 to 1,420 km². Model predictions of capacity were significantly correlated to observed maximum production of juvenile steelhead (<EM>P </EM>< 0.005, <EM>R</EM>² = 0.88), as was watershed area (<EM>P </EM>< 0.005, <EM>R</EM>² = 0.88). The UCM predictions revealed that parr capacity was unevenly distributed in the watersheds, and that habitat quality (smolt capacity/m²) differed between reaches among all watersheds by up to 15-fold across seven basins surveyed, and ranged more than 10-fold between reaches within four of seven test watersheds. Thus, the UCM can be used to discriminate stream reaches and features that either warrant habitat restoration or conservation. Key factors driving high or low habitat quality differed between reaches, and included pool area, riffle depth, boulder substrate, alkalinity, fine sediment, and turbidity. The UCM provides a framework for understanding the habitat features that determine the production potential of a basin, for identifying factors that limit production, and for predicting potential fish benefits from differing habitat management strategies.

Radioactive Methods

Radioactive decay can best be explained by accepted models of atomic or microscopic structure. By the mid 20th century most people understood that the atom was the smallest particle to which a homogeneous macroscopic sample could be subdivided and retain the physical characteristics of the original sample. The atom was called a microscopic particle because its dimensions were on the order of 10-8 cm. It is now known as mesoscopic, and the microscopic world is the subnuclear, or less than 10-13 cm, the distance across most nuclei. Physicists develop their intuitive feel for nature using such characteristic distances as 10-8 cm, called an angstrom (abbreviated Å). If you lived at the mesoscopic or microscopic level, you would choose this distance unit because it would be convenient. Today these levels are discussed as the nanoworld or nanostructure level.1 We shall refer to the microscopic/nanoscopic under the general term microworld. The energy required to separate two atoms coupled together is of the order of 0.1 electron volts. This is an energy unit characteristic of atoms, abbreviated as eV. In the macroscopic world, whose dimensions are most familiar to us, characteristic distances are of the order of 1 cm, which is 100 million times that of the microworld. The macroworld energy unit we are most familiar with is the food calorie, which is 1,000 heat calories, which is, in turn, about 4,180 joules. In the microworld, the electron volt is 1.6 X 10-19 joules. In the microworld, atoms consist of nuclei, which are about 10-13 cm across and which contain almost all of the mass of the atom. The nuclei, in turn, consist of protons and neutrons. These are two of the four elementary particles with which we will be concerned. Nuclei can be thought of as built up of nucleons or baryons, members of the larger class of elementary particles, hadrons. Baryons are composed of even smaller particles known as quarks. Particles like electrons, muons, and neutrinos are known as leptons.