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The population dynamics of perennial crop plants are influenced by numerous factors, including management practices. Conditions in the field vary from year to year, and matrix population models are useful for evaluating population behaviour in relation to environmental variability. In Missouri, the stand persistence of birdsfoot trefoil (Lotus corniculatus), a perennial legume, is often limited by disease and poor seed production. A stage-based, matrix population model was developed to evaluate the population dynamics of birdsfoot trefoil in relation to clipping treatment. The plant growth stages represented in the model were seeds, seedlings, mature vegetative and reproductive plants. Two phases of population growth were evaluated in clipped and unclipped stands. Establishment-phase populations were characterized by relatively high mortality and low reproduction. Elasticity analysis indicated that growth of these populations was most sensitive to the survival of vegetative plants. Mature vegetative plants and seeds comprised the majority of surviving individuals in clipped and unclipped populations, respectively; however, establishment-phase populations under both management treatments tended toward extinction. Populations in the post-establishment phase of growth were characterized by relatively low mortality and high reproduction. Population growth in this phase of growth was most sensitive to seed production, and most individuals in these populations were at the seed stage.

This paper presents a method for calculating atmospheric transmittance from direct-beam solar spectral irradiance measurements under cloudless skies by treating spectral irradiance as a multichannel sun photometer. Computing the ratio of the measured spectral irradiance to the extraterrestrial spectral irradiance at the top of the atmosphere produces the atmospheric transmittance as a function of wavelength. Individual band absorber amounts and scattering parameters, based on the LOWTRAN 7 atmospheric transmittance model, are then extracted from the transmittance using iterative fitting over wavelength regions where only a few species are active. Using these parameters to extrapolate the entire terrestrial solar spectrum, the wavelength-integrated spectral irradiance is shown to be within 2% of the total irradiance measured with an absolute cavity radiometer. Instrumentation and procedures that have been used with the method at the National Renewable Energy Laboratory since 1987 are described, al...

Peach fruit are most susceptible to infection by Monilinia fructicola during the preharvest ripening stage. Although various sources of inoculum for preharvest infection have been characterized, the role of latent infection of immature fruit in the carryover of M. fructicola from the spring (blossom blight phase) to the preharvest period (fruit rot phase) is unknown for the southeastern United States. From 1997 to 1999, immature peach fruit were collected at 14-day intervals from orchards in middle and northern Georgia. Fruit were surface disinfested and treated with paraquat (1997) or frozen overnight (1998 and 1999) to induce tissue senescence and activate latent infections. Across sites and years, the incidence of latent infection remained low until the final sampling date 7 to 12 days before harvest. The incidence of latent infection on the final sampling date ranged from 0 to 22.0% and correlated significantly with both the incidence of blossom blight earlier in the season (r = 0.9077, P = 0.0332) and the incidence of fruit rot at harvest (r = 0.9966, P = 0.0034). There also was a significant association between the incidence of latent infection at the onset of pit hardening (between 7 and 10 weeks before harvest) and subsequent fruit rot incidence (r = 0.9763, P = 0.0237). Weather variables (cumulative rainfall or rainfall frequency) alone did not correlate with fruit rot incidence (P > 0.05), whereas combined latent infection-rainfall variables did. The results suggest that latent infections can serve as a source of inoculum for subsequent fruit rot in peach orchards in Georgia. Despite its significant association with fruit rot incidence, the potential for using latent infection incidence as a biological indicator of disease risk at harvest may be limited; the assessment of latent infection during the fruit ripening stage (similar to the timing of the final sampling date in this study) would not provide sufficient lead time for preharvest disease management decisions, whereas an earlier assessment (e.g., at the onset of pit hardening) would require large sample sizes due to the low incidence of latent infection present during that period.

During a comparison of the growth of human populations Emery (1994) noted a curious uniformity in ratios of populations in largest cities versus populations in host nations. This present article is intended to explore the relationship a bit further to interest perhaps a few professional demographers in some of the relationships and their possible causes....Information was provided by relating populations of largest cities to those of host states in the United States and then populations of second largest and tenth largest cities of host states. For a longer view the city/state analysis was extended from 1990 to 1940.... (EXCERPT)

The purpose of this study was to evaluate the efficacy of MR imaging in predicting the pathologic diagnosis of soft-tissue masses, both neoplastic and nonneoplastic, and in distinguishing benign from malignant lesions.The imaging features of 225 soft-tissue tumors (179 benign, 46 malignant) in 222 patients were analyzed. Univariate analysis of multiple individual imaging features was done, along with stepwise logistic regression analysis of combinations of imaging features, to determine how useful these are for predicting malignancy or benignity. A subjective (group consensus) analysis of each case was done prospectively, and each tumor was placed into one of three diagnostic categories: (1) benign, diagnostic of a specific entity; (2) nonspecific, most likely benign; or (3) nonspecific, most likely malignant. Results were compared with the final diagnosis established by pathologic examination (n = 184) or imaging/clinical data (n = 41).By quantitative analysis, no single imaging feature or combination of features could reliably be used to distinguish benign from malignant lesions. For the subjective analysis, a correct and specific benign diagnosis could be made on the basis of MR imaging findings in 100 (44%) of the 225 tumors. For the entire cohort, the sensitivity was 78%, the specificity was 89%, the positive predictive value was 65%, and the negative predictive value was 94% for a malignant diagnosis. When the diagnostic benign tumors were excluded, the specificity and negative predictive value decreased to 76% and 86%, respectively, whereas the sensitivity and positive predictive value remained the same.Many benign soft-tissue masses can be correctly and confidently diagnosed with MR imaging. The prevalence of benign lesions among soft-tissue masses accounts for the relatively high specificity and negative predictive value that can be achieved with MR imaging for tissue characterization. However, the accuracy of MR imaging declines when these characteristic benign tumors are excluded from analysis. A significant percentage of malignant lesions may appear deceptively "benign" with the currently used criteria. For lesions whose imaging appearance is nonspecific, MR imaging is not reliable for distinguishing benign from malignant tumors, and these lesions warrant biopsy in most cases.

The geological history of the Earth is replete with examples of animals proliferating to numbers that exceeded the ability of their environments to provide support. Enormous numbers and widespread distributions of many animals sometimes have been followed by drastic reductions in numbers of individuals and even by complete extinction of species. Humans of many nations are following the same trend of population growth beyond the ability of resources to insure adequate food, clothing, shelter, safety, and transport and beyond the ability of Earth to accommodate the wastes. Human population is now 5.4 billion, with a present doubling time estimated at about 35 years. Is this uncontrolled proliferation also to be followed by severe reduction or even extinction? If not, how may human population be stabilized or reduced to a level commensurate with resources and waste disposal—more effective contraceptives, increased abortion, high taxes on procreation? An approach more effective than religion or political control may be through better education (increased percentage literacy) that is known to correlate with lower birth rates and increased national income per capita in the about 167 nations of the world. If leadership cannot soon rise to face this situation, human inhabitation of the Earth may become much more complicated in the not distant future.

Flattenings that may be shelves formed by marine erosion/deposition or by slump masses are present on continental margins of southern Africa that border both the Atlantic and Indian oceans. Breaks in slope, indicated along sounding lines, suggest that a shallow terrace of the Atlantic margin has been warped downward from depths of about 130 m southward to about 200 m, and a deeper terrace lies between depths of about 150 m to about 440 m. Examination of contours and hypsometry (areas measured between depth contours) show widespread flattenings at about −65 and −95 m on the Indian Ocean margin and −125, −155, and −190 m along the Atlantic margin. Seismic profiles indicate that some of these and other more local flattenings are on slump blocks and thus are not correlatable for long distances. An additional complication is that sediment introduced by rivers is transported alongshore by wave-induced and oceanic bottom currents, and that their deltas are ephemeral.

Pangaean divergent margins caused by the breakup by rifting of that supercontinent display three distinct evolutionary stages. In their youth or rift stage, divergent margins display a synsediment fault style that has considerable tectonic instability. During the mature or drift stage (seafloor spreading) continental margins are relatively stable and are dominated by thermal subsidence. These two stages (rifting and drifting) are separated in many areas by an unconformity coeval with the oldest associated oceanic crust — the breakup unconformity; in some areas the onset of seafloor spreading is marked by intense magmatic activity. Sediment facies the rifting stage range from continental clastics landward of the continental basement hinge and along the flanks of the basin to saline deposits and more open-water carbonates in the axial zone of the rift. Lithologies emplaced during the rift or mature stage of margin development range from shallow clastics/carbonates to deep-water carbonate/siliceous oozes, turbidites and contourites, some of which were deposited in an anoxic environment. Deposition then is controlled by changes in configuration of basins, changes in sea level, and plate migration through several climatic belts. During the final, or old-age, of margin development, divergence gives way to convergence. This stage, which generally terminates with continental collision, is characterized by tectonism, magmatic activity, and crustal shortening. Mesozoic divergent margins along the east-west trending former Tethys Ocean have reached this stage in their evolution.

Surveillance for coccidioidomycosis (CM) and a case-control study for risk factors among adults were conducted in Kern County, California. From January 1995 through December 1996, 905 cases of CM were identified, for an annual incidence of 86 cases per 100,000 population. A total of 380 adults were enrolled in the case-control study: 77 had severe pulmonary disease, 33 had disseminated disease, and 270 control patients had mild disease. Independent risk factors for severe pulmonary disease included diabetes, recent history of cigarette smoking, income of < $15,000 per year, and older age. Oral antifungal therapy before hospitalization was associated with a reduced risk of CM pneumonia. Risk factors for disseminated disease were black race, income of < $15,000 per year, and pregnancy. Early treatment of CM with oral antifungal agents may prevent severe pulmonary disease in groups considered to be at high risk, such as elderly individuals, persons with diabetes, and smokers. Persons at risk for severe CM may benefit from vaccination once an effective CM vaccine is available.

Deposition of glycosaminoglycans and laminin-1 in the renal corpuscles of the kidneys of mylencephalic blebs, 'blebs', (my) and normal C57BL/ 6J mice was compared in embryonic, neonatal (newborn to approximately two days old) and adult animals. Utilization of Alcian Blue 8GX staining, at a pH of 2.5, revealed an increase in acidic glycosaminoglycans in the parietal layer of Bowman's capsule and in general, an increase in the mesangial matrix of the glomerulus of my mutant adults. An increase in glycosaminoglycans was also noted in the developing kidney in certain my embryos in tissues associated with the glomeruli, but no significant differences were observed between the kidneys of neonatal my and control mice. The laminin-1 procedure revealed more deposition of laminin in the basement membrane of the parietal layer of Bowman's capsule in the neonatal and adult mutant my mice. Altered deposition of basement membrane and extracellular matrix components may reflect changes in the pattern of development and in the functioning of the kidney. Morphological changes in the human kidney are associated with alteration of function; a similar association may be occurring in the mice homozygous for the my gene.

Of medical and surgical emergencies in the pediatric abdomen, those involving the spleen are relatively less common than other abdominal organs, though equally important to recognize. A more sophisticated clinical understanding of the important role of the spleen in immunocompetence has developed in parallel with advancements in imaging. A healthy respect for the preservation of splenic tissue has emerged, altering traditional surgical management of splenic emergencies. Non-invasive imaging has come to play a vital role in depicting acute abnormalities and in determining the need for conservative, interventional, or surgical management.

Plague was confirmed in the United States from nine western states during 1995. Evidence of Yersinia pestis infection was identified in 28 species of wild or domestic mammals. Thirteen of the plague positive species were wild rodents; 15 were predators/carnivores. Yersinia pestis was isolated from eight species of fleas. Seven confirmed cases of human plague were reported in 1995 (New Mexico 3; California 2; Arizona and Oregon 1 each). Five of the seven cases were bubonic; one was septicemic and one a fatal pneumonic case. Months of onset ranged from March through August. In California, during 1995, plague was recorded from 15 of the 58 counties. Over 1,500 animals were tested, of which 208 were plague positive. These included 144 rodents and 64 predators/carnivores. Two confirmed human cases (one bubonic and one fatal pneumonic) occurred, both in Kern County. Case No. 1 was reported from the town of Tehachapi. The patient, a 23 year-old male resident, died following a diagnosis of plague pneumonia. The patient's source of plague infection could not be determined precisely. Field investigations revealed an extensive plague epizootic surrounding Tehachapi, an area of approximately 500-600 square miles (800-970 square kilometers). Case No. 2 was a 57 year-old female diagnosed with bubonic plague; she was placed on an antibiotic regimen and subsequently recovered. The patient lives approximately 20 miles (32 km) north of Tehachapi. Field investigations revealed evidence of a plague epizootic in the vicinity of the victim's residence and adjacent areas. Overall results of the joint field investigations throughout the entire Kern county area revealed a high rate of plague positive animals. Of the numerous samples submitted, 48 non-human samples were plague positive.

The two large lakes named Samra and Lisan existed in the Dead Sea graben from 350,000 to 120,000B.p. and 60,000 to 12,000B.p. Their sediments tentatively are correlated with the European Riss and Würm glacial epochs. Thick marls are the chief sediments in the deep water north basin. Rocksalt deposition dominated within the troughs of both north and south basins throughout the intervening Riss-Würm Interglacial stage. Lithology of Lisan Formation (Würm) in that basin indicates rapid and extreme fluctuations of level. Eight major climatic cycles are recorded during Würm glaciation when the level fluctuated between -180 m m.s.l. and probably lower than -400 m m.s.l. Rocksalt was deposited within both basins during warm dry phases of the Lisan stage. At the present state of knowledge no specific tectonic or volcanic activities can be tied to these climatic events. The Holocene Period was similar lithologically to that of the Lisan Formation and transition between them was gradual. Primarily the difference between the two was change in relative time span between alternate wet and dry phases. Dry phases of Holocene gradually became longer while wet ones with Dead Sea transgressions became shorter. Tectonic regimes during the first part—the Natufian age to Early Bronze III, 12,000 to 4400 B.P.—seem to have been milder than later ones, end of Early Bronze III to the present. The severe earthquake that destroyed Sodom and Gomorrah in 4350 B.P. was followed by a 300-year long subphase of gradually warming climate that became extremely dry during the latter part of the Intermediate Bronze age. Climatic Wet Phase III began about 3900 B.P. It was the longest, about 800 years, and most intense wet phase of Holocene and it probably was associated with volcanism. No abrupt cultural or demographic changes are known during transition from Epi-Paleolithic or Geometric Kebaran from the last glacial phase of the Pleistocene Period through Natufian to the early part of Holocene Pre-Pottery Neolithic. The reason for this stability is not clear especially because average temperatures of global oceans during the latest Pleistocene glaciation were appreciably lower than those during Early Holocene (Emiliani, 1978).

The story of the destruction of Sodom, Gomorrah, and Jericho--three cities situated along a major fault line extending 1,100 kilometers from the Red Sea to Turkey--is the oldest such description in human history. In this book, noted geologists K.O. Emery and David Neev have revisited that story to shed light on what happened there some 4,350 years ago. With all the benefits of modern geological and forensic science techniques at their disposal, the authors explore an area where earthquakes, volcanic activity, variations in the Dead Sea's level, and oscillations between arid and wet climates have affected life there for over 10,000 years. In reviewing the geology, biblical paleogeography, and limnology of the region, the authors have produced fascinating insights into the tectonic and climatic changes that have occurred in the region over the last 6,000 years and how those changes have affected cultural life in the Middle East. The Destruction of Sodom, Gomorrah, and Jericho is the first book to combine modern science and biblical archaeology to produce an authoritative account of the of these three great cities. It will fascinate students and researchers in geology, geophysics, and archaeology alike.

The thrilling biblical saga of Sodom and Gomorrah leaves a deep impression on the spirit of its readers, especially the young. Basic ethical concepts such as right and wrong were dramatically portrayed by that simple and cruel, yet humane, story. Memories of even more ancient disastrous geological events apparently were interwoven into the saga. A geologist cannot remain indifferent when investigating the Dead Sea region and observing stratigraphical and structural evidence of past and continuing similar events. Forceful dynamics indicated by vertically tilted beds of rocksalt layers that have penetrated upward through the ground and by later processes that have shaped some beds into pillars trigger association with the ancient story. Such features are abundant and clearly recognizable along the foot of the diapiric structure of Mount Sedom (Arabic Jebel Usdum). A gas blowout during the drilling of a water well near the Amazyahu fault in 1957 only by good luck failed to produce a gush of fire and smoke. Such an event could have happened in ancient times as a natural result of faulting. Knowledge of the regional geological background permits translation of the biblical descriptions into scientific terms, which suggests that the sagas of Sodom, Gomorrah, and Jericho described real events that occurred during ancient times before much was known about geology. Thirty-five years of the authors' professional experience in the Dead Sea region encompasses many geological aspects of the basin: deep and shallow stratigraphy, structural history, seismology, sedimentological processes, and the physical and chemical properties of the water. Archaeological studies in the region are reviewed. Although most of these studies are applicable to exploration for oil and gas or extraction of salts from brines, their results illuminate the role of changing paleogeography and paleolimnology on human environments. Climate changes and lake-level fluctuations have occurred since Mid-Pleistocene, especially during the past 50,000 years. Studies of sediments from shallow core holes delimit coastal areas that when exposed by drops in the level of the Dead Sea, quickly developed soils that could be used for agriculture.

The Dead Sea occupies a linear down-dropped region between two roughly parallel faults along the central segment of the major northsouth- trending crustal rift that extends about 1,100 km from the Red Sea through the Gulf of Elath to Turkey. This rift or geosuture separates the Arabian crustal sub-plate on the east from the Sinai one on the west. An origin as early as Precambrian is possible (Bender, 1974; Zilberfarb, 1978). Crystalline crust along the north-south trough of the Sinai sub-plate is about 40 km thick in contrast with a thickness of half as much above ridges along both flanks (Ginsburg and Gvirtzman, 1979). Toward the north the ridges appear to converge (Neev, Greenfield, and Hall, 1985). Since the Miocene period the Arabian plate has moved north about 105 km relative to the Sinai plate. This sort of crustal movement along either side of a rift is termed strike-slip faulting. One result of it was the opening of the Red Sea relative to the Gulf of Suez. The Dead Sea graben, a down-dropped block between two roughly parallel faults, occupies the central segment of the long crustal rift. The boundary between these is rather sharp along the east shore of the sea (Frieslander and Ben-Avraham, 1989). Actual post-Miocene movement was along not just a single major fault but was distributed among numerous sub-parallel faults that form a 100-km-wide belt in which movements were transferred from one fault to another (Eyal et al., 1981; Gilat and Honigstein, 1981). Recent movements have occurred along the south segment of the north-south-trending Arava fault south of the Amazyahu transverse fault (Zak and Freund, 1966). These strike-slip movements probably did not continue after Miocene along the main East fault of the Dead Sea, which is the north extension of the Arava wrench fault. In contrast, recent movements have been present along the north-northeast- trending Jordan or Dead Sea fault (Ben-Menahem et al., 1977, fig. 1). The movements extend south from east of Jericho in the north along the base of the west submarine slope of the sea and the elongate salt diapir of Mount Sedom as far as the Amazyahu fault in the south.

In contrast with the rocky planets, the gaseous planets beyond the Asteroid Belt consist of a rocky core mantled by thick ices of water, methane, and ammonia, liquid metallic hydrogen, and liquid molecular hydrogen (Hartmann 1983, p. 294). Jupiter may be experiencing an anomalously slow cooling because of condensation and settling of helium-rich droplets from a hydrogen-helium mixture; a similar process also may be occurring on Saturn (Klepeis et al. 1991). The satellites orbiting the gaseous planets have various origins ranging from accretion from a disk of gas from a previous larger satellite, to fragmentation, and reconsolidation (a process that may have occurred more than once), and capture. The internal structures displayed by these satellites include a total molten stage model except for a rigid thin solid crust on Io. However, Schubert et al. (1986) believed that there are problems with this molten model of Io and have proposed instead a model consisting of an Fe-S core, a solid mantle, a molten or partly molten asthenosphere, and a rigid crust. Models proposed by Schubert et al. for the other satellites include mostly rock (hydrated or dry silicates) covered by water and an ice crust (Europa), and differentiated bodies having rock cores covered by ice mantles and undifferentiated structures of homogenous ice rock mixtures. Thus, the tectonics and internal dynamics of these satellites are controlled by the rheology and viscosity of high-pressure and low-temperature forms of ice (Poirier 1982).

In the broadest sense, we consider that the morphologies of rocky members of the Solar System (Table 1, listed in order of distance from their host) can be grouped into three categories: endogenic, exogenic, and exotic. Endogenic provinces are ones that were produced by internal forces that caused plate movements and interplate and intraplate magmatic/tectonic activities. Exogenic provinces are ones that owe their origin to external processes such as weathering, erosion, transportation, and deposition from earlier rock surfaces; therefore, they require the presence of a hydrosphere (or other liquid) and an atmosphere (Table 2, listed in order of decreasing diameter). Exotic provinces are ones created by bombardment of the planets or satellites by planetesimals and comets; this bombardment has produced large regions of terrae (impact craters), planitias (flat plains of debris ejected from impact sites), and impact melts (country rock melted by the kinetic energy of impact on rocky planets and moons).

Our Universe is believed by many astronomers and geologists to have begun 10 to 20 Ga ago with an outrush of material during the ‘Big Bang.’ Other cosmologists question the concept of the Big Bang, stating that it reflects search for a creation and a beginning (Burbidge 1992; Powell 1992); they proposed that creation is continuous and occurs in a series of little bangs. Was the Big Bang the beginning of time? If not, what came before it (Hawking 1988)? Should one visualize the Cosmos as having a beginning without a beginning, and an end without an end, as Merritt (1932, p. 30) described Khalk’rus? The present concensus is that the expansion of the Universe after the big bang appears to have gone through two stages: first, a period of rapid acceleration and inflation, when all distorting influences diminished quickly, and second, a phase when the Universe developed its present highly symmetrical state of expansion (Barrow 1991, pp. 49–50; Halliwell 1991). Stars, galaxies, and clusters of galaxies aggregated within this outrushing material when the Universe was about 1 Ga old (Riordan and Schramm 1991, pp. 3, 21; Powell 1992). Measurements on the broadest scale indicate nearly uniform radiation within the Universe, but recently the Cosmic Radiation Explorer (a satellite of the National Aeronautics and Space Administration — NASA) has mapped small variations in temperature attributed to the irregularities in radiation produced by the Big Bang. Within the past decade more detailed mapping has shown a nonuniform distribution of galaxies separated by huge voids, sheets of galaxies (such as the Great Wall, the largest coherent structure known within the Universe), and large foam-like distributions of galaxies (Spergel and Turok 1992). More than 90% of the material in the Universe consists of dark unseen matter generated during the inflation phase and required by density considerations. This dark matter is in a form that is difficult to detect, possibly as black holes, brown dwarfs, or planetary blobs the size of Jupiter or smaller (Riordan and Schramm 1991, pp. 61–62).

The minority‐carrier lifetime of polycrystalline CdTe has been measured for a variety of samples produced by two different growth techniques. The CdS/CdTe solar cell structures were either grown by a proprietary spray technique at Photon Energy, Inc. or by close‐spaced sublimation at the University of South Florida. The photoluminescence decay lifetime is investigated as a function of grain size, excess carrier density, and temperature. Results are consistent with carrier recombination at grain boundaries, indicate some defects act as traps, and show relatively high efficiency solar cells can be made from material exhibiting sub‐nanosecond lifetimes.

Relative sea levels (RSL) have changed constantly throughout geologic time as the volume of ocean waters has fluctuated, the shapes of the ocean basins have changed, and the land masses have been broken apart, been welded together, and have emerged or submerged. The challenge is to separate changes in level of the land from changes in level of the ocean surface in an unambiguous fashion, a task that only partly can be successful given the broad spectrum of processes affecting relative sea levels, especially those processes that contribute to the low-frequency portion of the spectrum. To separate land-level changes from sea-level changes effectively, a diverse mixture of geological and geophysical approaches must be integrated. Some contributors to relative sea-level change and their approximate magnitudes are summarized here in a general way, with documentation for some of the more important processes concentrated in later and more pertinent sections of the book. From this summary one can differentiate between processes presently affecting relative sea level and those that were important only during the past.

The broadest view of changes in relative sea levels or land levels is given by histograms based on all tide-gauge records of 10 or more years’ duration. One such histogram (Fig. 37) is an update and modification of the insert at the lower left of Figure 35 and contains more than twice as many tide-gauge records. Note that the modal change of relative sea level is a rise of approximately +1.0 mm/y. and that rises and falls occur in both hemispheres. Hemispheric relationships are clearer in Figure 38A, which shows far more tide-gauge records in the north than the south. This latitudinal distribution is the reverse of the distribution of ocean area, but it accords with the distribution of large seafaring industrial nations of the world. Moreover, the fall of relative sea level (rise of land) is mainly but not solely caused by removal of crustal loads by melting of glaciers. Many stations that show rise of relative sea level are at low latitudes where they probably are the result of tectonic uplift (mainly faults, folds, volcanoes) as well as rise in the ocean level.

In the previous chapter tide-gauge records from different regions of the world were investigated, with particular attention paid to those in regions having many tide gauges with acceptable records in terms of time spans and systematic trends. Both worldwide and regional examinations showed the trends of change in mean annual levels to be too variable for those trends to represent a simple eustatic rise of sea level caused by return of glacial meltwater or by heating of ocean water through climatic warming during post-glacial or even during the span of the industrial revolution (the greenhouse effect). These records reveal rise of relative sea level at some sites simultaneously with fall in relative sea level at other sites. Sites of the opposing trends may be nearby or distant, and the records commonly are supported by others within groups of nearby stations. Short-term changes in the record caused by tides, storms, and tsunamis are filtered out by the hourly averaging process for each year of record.

Changes of mean annual sea level are so slow that they scarcely can be observed by humans, especially because they are obscured by much longer and faster but briefer changes caused by waves, tides, and episodic tsunamis and storm surges. Local changes of land level, however, often have been observed in association with uplift or downdrop along faults or folds that are at or near the shore. These movements may span several meters vertically in only a few seconds or minutes, and they can permanently submerge roads and buildings or strand ships and fishing facilities above the surface of the ocean. Slower, but still observable during a lifetime are broad downwarpings associated with removal of groundwater (as at Venice, Italy) and of oil (as at Long Beach, California, and other coastal oil fields) as well as subterranean movements of magma (as at Pozzuoli, Italy). Direct observation also cannot provide direct information on changes of sea level, either real or relative, that occurred before humans were present or before the invention of written records.

Prediction of the magnitude, timing, and severity of human influence on climate is elusive, but considerable effort has been spent identifying geographic areas and natural processes that are sensitive to climate change. Studies of impacts have been performed for different scenarios of climate change and have focused on the vulnerability of individual regions. Although useful for sensitivity analysis, these approaches are limited because they commonly neglect the full suite of physics associated with climate change. For instance, sea-level rise, the primary concern here, is assumed to inundate coastal regions with little if any consideration for self-maintenance processes such as longshore and cross-shore sediment transport or dynamics of barrier beaches. Essentially, the uncertainties for predicting climate change are compounded by the uncertainties in the modeling of impacts given that climate change. However, a broad range of climate-change impacts can be discussed with some degree of certainty, including some effects of possible increased rate of relative sea-level rise.

Scientific consensus on the causes of climate change during the achanges. This uncertainty is illustrated by the debates about the magnitude of global warming during the past century. Whereas few debate that global warming has occurred during the past century, as the Earth emerged from the Little Ice Age, the magnitude of the warming and its possible causes are unclear. The prediction of future climate is fraught with even greater difficulties and uncertainties. Prediction of future climate change can be either empirical or based on numerical models. Each technique makes significant assumptions that cause the predictions to differ substantially for many scenarios of climate forcing. The historical record of climate and the prediction of future climate are discussed separately below.

The records of the world’s tide gauges can provide more precise and more widespread information about changes of relative sea levels during the past century than can be expected from radiocarbon or other kinds of measurements. Annual average levels at each station can be computed and compared with levels at the same station during earlier or later years as well as at other stations. If the year-by-year changes are systematic at a given station, each annual average tends to reinforce the others. Thus, a station record of many years is inherently stronger than a single radiocarbon date on organic or carbonate material that was deposited at a somewhat uncertain elevation above or below mean sea level.

In a recent letter, Kim et al. reported on a 6.1% efficient polymer photovoltaic cell. The reported 6.1% efficiency under standard reference conditions 25 °C, 1000 W m−2 total irradiance, IEC 60904 global reference spectrum is not consistent with the device’s reported quantum efficiency QE . The 6.1% claim comes from Fig. 3 for cell D2. The shortcircuit current density Jsc for this cell is not reported. However, digitizing the data in Fig. 3 yields a Jsc of 15.42±0.05 mA /cm2. Assuming the QE in Fig. 2 C at 297 K corresponds to the QE of cell D2, then this QE integrates to 8.40 mA /cm2 with a maximum QE of 61.8%. To make the QE in Fig. 2 C agree with the reported Jsc corresponding to the claimed 6.1% efficient cell, the maximum QE has to be 113%. This is not physically possible. Or conversely, the efficiency would have to be 3.3%. Claims that this is not the QE of cell D2 will have a relatively small effect, provided the wavelength range of the photoresponse is comparable. Since a well-calibrated reference cell was used and an attempt was made to estimate the spectral error, the mistake is probably in the device area—which is not unexpected for a device with an area less than 10 mm2. This implies substantial current or light collection outside the reported area.

Foliar diseases of alfalfa in four fertility treatments and an untreated control were evaluated in relation to microclimate, host growth, and soil fertility during 1991 and 1992. Over the course of six growth periods, alfalfa growth and disease development varied significantly. Disease incidence and severity were greater on leaves from the lower half of shoots than on leaves from the upper half. Disease development depended on moisture conditions. The relationship of disease to moisture varied between the upper and lower halves of shoots. Disease on the lower half of shoots was correlated with leaf wetness duration as well as atmospheric moisture conditions; disease on the upper half of shoots was correlated only with cumulative rainfall

A total of about 1100 well-distributed samples of suspended matter in surface waters off the length of eastern Asia are available. From these samples, 180 were selected for detailed examination of the non-combustible fraction using optical and electron microscopy along with computer methods of particle measurement and counting. The results showed that, generally, all major components of the suspended matter are most abundant in the nearshore belt (combustible fraction, mineral grains of silt size, skeletal debris, and clay minerals), the result of mechanical transport of detrital sediment and chemical transport of nutrients from the land. Mineral grains of silt size average about 2%, skeletal debris plus clay minerals—23%, and combustible organic matter—75% of total sample weights, but the last two categories vary over a wide range depending upon geographical positions of the samples. Most evident is an oceanward decrease in percentage and concentration of the total noncombustible fraction and an oceanward increase in median diameter of the mineral grains.

Limestones of Oligocene age obtained from a submersible at two sites about 3,000 m deep on the Oriente Slope and from two shallow drill holes on nearby Grand Cayman Island were deposited in shallow marine waters. All samples contain calcareous algae and shallow-water foraminifera, but no deep-water remains were found. The limestone on the slope was lithified in fresh water, according to its petrography and stable isotopes. A third dive encountered massive beds presumed to be outcrops of limestone that dip southward down the slope. We conclude that the region began to subside along a hinge line parallel to the Oriente Slope during Oligocene time and soon became too deep to generate a shallow-water carbonate deposit. This subsidence was associated with plate movements along the Cayman Trough.

Heterojunction solar cells have low‐cost potential for meeting the long term economic goals for the photovoltaic technology. In this paper, a critical technical evaluation of the ITO/GaAs solar cell is presented, emphasizing the factors limiting the performance of the device. The devices are fabricated on p‐type (Be‐doped) GaAs grown by MBE, with the ITO deposited by ion beam techniques. Light and dark J‐V characteristics are presented and compared for these devices. The formation of buried homojunctions is postulated for cells damaged due to ion beam deposition, leading to higher Voc and low Jsc. Heterojunction formation is found for minimally disrupted GaAs surfaces. AES depth profiles are used to evaluate the chemical width of the ITO/GaAs interfaces. Electrical data characterizing the ITO/GaAs interface are obtained using EBIC, C‐V and intensity dependent Voc‐Jsc characteristics.

Mean annual sea levels at 247 tide-gauge stations of the world exhibit a general rise of relative sea level of about 3 mm/year during the past 40 years. In contrast, general uplift of the land is typical of high northern latitudes, where unloading of the crust by melt of Pleistocene ice sheets is significant. Erratic movements are typical of belts having crustal overthrusting and active volcanism. Short-term (5- and 10-year) records reveal recent changes in rates, but such short time spans may be so influenced by climatic cycles that identification of new trends is difficult, especially with the existing poor distribution and reporting of tide-gauge data.

Detailed photographs repeated in 1979 after several decades and other measurements at La Jolla, California, provide information about processes and rates of rock-shore and sea-cliff erosion. Weathering and abrasion cause direct surface retreat particularly on steep slopes, but they are very slow on near-horizontal benches. Mass movements are episodic, and their resulting talus is comminuted rapidly by surface abrasion through sand-laden waves and currents. Measured rates of the various processes of marine erosion span a wide range but constitute a reasonable hierarchy for different exposures, processes, and lithologies.

About 4100 samples of suspended matter were collected by filtration of surface ocean waters in three large regions on the western sides of oceans and two on the eastern sides. Comparison of results shows that the non-combustible fraction (chiefly detrital clays and silts with some siliceous and calcareous skeletal debris) generally dominates along the western sides of oceans, where large contributions of solid detrital sediment are made by rivers that drain much of the adjacent continents. The combustible fraction also is important off these rivers, but it is more important (both relative to the non-combustible fraction and in absolute terms) along the eastern sides of oceans, where upwelling is intense.

Components of suspended matter in surface waters between western Africa and the Mid-Atlantic Ridge were removed by filtration and measured by scanning electron and optical microscopy. Skeletal debris from diatoms, dinoflagellates, and other plankton are most concentrated in Antarctic surface water and in regions of coastal upwelling. Detrital mineral grains are most concentrated in nearshore regions, from discharge of major rivers, erosion of sea cliffs, and deposition from offshore winds. Farther offshore are high concentrations of mineral grains brought by trade winds from deserts in both northern and southern Africa. The winds also bring freshwater diatoms and woody tissue. The remaining component on the filters is marine organic matter, mostly in thin films. These films trap skeletal debris and mineral grains. Presumably, animals that graze upon the films further concentrate the grains into faecal pellets whose rapid settling carries the grains into deeper waters and to the bottom. The films were found in all other areas of the world ocean from which surface samples were spot-checked: off eastern Asia, off eastern North America, and the central Pacific. Thus they appear to be a major factor in marine sedimentation. In areas of upwelling off western Africa, the total suspended matter in surface waters averages about 0.1 mg/1 of filtrate, about five times that present in the open ocean. It consists of about 70% organic matter, 29.6% skeletal debris, and 0.4% mineral grains, in contrast with concentrations in the open ocean of 90%, 8% and 2%, respectively.

The land areas of the world are mostly between 30° S. Latitude and 70° N. Latitude, and the several plans for ocean‐floor sovereignty change this pattern but little. Probably by coincidence the latitudes of maximum population are the same as the latitudes of maximum oil production (20° to 40° N. Latitude). In contrast, the greatest concentrations of nations are farther south, and the greatest concentrations of gross national products are farther north.

Records from 22 tide-gauge stations along the mainland coast of eastern Asia document low-frequency vertical movements of the land perhaps biased by unevaluated changes of sea level. The land is rising (relative to sea level) as much as 5 mm yr−1 in the areas of massifs and ancient foldbelts and subsiding as much as 9 mm yr−1 in areas of Cenozoic basins and foldbelts. Although the tide-gauge records are sparse, inferences from them are supported by the stratigraphy and structure of the region, and by raised and submerged sea-level terraces. Thus, relative changes of sea level are heavily influenced here by tectonic and isostatic as well as eustatic factors, just as in Japan, Scandinavia, and North America where tide-gauge records are much more abundant. Higher frequency (2–25-yr periods) sea-level fluctuations show broad peaks between 2 and 4 yrs, and near 10 yrs. Some of these fluctuations correlate with behavior of the Kuroshio Current, which along with freshwater inflow dominates the hydrography of the eastern Asian continental shelves. Observations of water mass fluctuations are too sparse to identify direct causes of all high-frequency variability.

Records from tide gauges in Israel and Egypt supplement the many geological and archeological investigations that have contributed information about relative sea-level changes in the Mediterranean region. Seven such records reveal changes during the past few decades that accord with prior inferences about land movements in this region (emergence along the coast of Israel and at Alexandria and subsidence at the Nile Delta and the head of the Gulf of Suez). Twenty-four other tide-gauge records for the rest of the Mediterranean region indicate more uniformity (submergence of land or rise of sea level) in the west, but with greater movements of the land attributed to probable plate underthrusting in Turkey and Greece, to volcanism near Mount Etna, to deltaic compaction at Izmir, and to deltaic compaction coupled with water pumping at the Po Delta.

SEM examination of suspended material collected by filtration from samples of surface waters over continental shelves and deeper areas off eastern Asia reveals the presence of irregular organic films that are longer, cover more filter area, and have more tapered edges in samples from nearshore than offshore regions. Associated diatoms include species diagnostic of coastal environments. Films and coastal diatoms are most abundant in waters above continental shelves where river discharges cause the waters to be more dilute than 33.5‰ salinity. Farther from shore, both films and skeletal elements are broken and partly dissolved. Skeletal elements, faecal matter, and other debris are trapped or adhere to the films, which therefore provide a concentrated food source for small organisms beyond nearshore regions of high primary productivity. The films contribute an unknown percentage of the total organic matter that reaches bottom sediments.