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Highly mobile predators can show strong numerical responses to pulsed resources, sometimes resulting in irruptions where large numbers of young invade landscapes at a continental scale. High production of young in irruption years may have a strong influence on the population dynamics unless immature survival is reduced compared to non-irruption years. This could occur if subordinate individuals (mainly immatures) are forced into suboptimal habitats due to density-dependent effects in irruption years. To test whether irruptive individuals had lower survival than non-irruptive ones, we combined necropsy results (N = 365) with telemetry (N = 185) from more than 20 years to record timing and causes of mortality in snowy owls (Bubo scandiacus), which irrupt into eastern North America during winter following high breeding output caused by lemming peaks in the Arctic. Mortality was more than four times higher in irruption years than non-irruption years, but only for immatures, and occurred disproportionately in early winter for immatures, but not adults. Mortality was also higher in eastern North America, where owl abundance fluctuates considerably between years, compared to core winter regions of the Arctic and Prairies where populations are more stable. Most mortality was not due to starvation, but rather associated with human activity, especially vehicle collisions. We conclude that immature snowy owls that irrupt into eastern North America are limited by density-dependent factors, such as increased competition forcing individuals to occupy risky human-altered habitats. For highly mobile, irruptive animals, resource pulses may have a limited impact on population dynamics due to low subsequent survival of breeding output during the nonbreeding season.

Despite extensive accounts in the literature describing Barred Owls (Strix varia) as obligate forest-interior species, Barred Owls have increasingly been observed in urbanized landscapes. To determine if certain habitat characteristics, such as mature urban trees, facilitate the occurrence of Barred Owls in developed regions, we deployed GPS transmitters on 20 breeding Barred Owls in northwestern South Carolina. We selected territories containing a gradient of development density and habitat types to examine predictors of home range size and habitat selection along an urban-rural gradient. We related nocturnal locations to habitat features using resource selection functions (RSFs). We explored differential use along a development gradient by modeling interactions between habitat parameters and measures of development in the home range. Home range size varied from 0.38 km2 to 3.38 km2; size increased with the percentage of treeless area in the territory such as agricultural fields and power lines. Distance to nest, tree height, and distance to canopy edge were the most important predictors of owl use. Barred Owl selection for roadsides and aquatic features increased with degree of fragmentation in the home range. This is the first resource selection study using GPS data to examine habitat use of Barred Owls in the context of development. Our results highlight the behavioral plasticity of a species previously described as sensitive to anthropogenic impacts. The presence of this large avian predator in urban forests suggests that retaining key habitat features can promote multi-trophic communities even when other aspects of the habitat are highly altered.

Due to the low detectability of Northern Saw-whet Owls (Aegolius acadicus; hereafter, NSWO) throughout their annual cycle, standardized monitoring during migration allows for population assessments over time. We assessed age-class population trends in NSWO throughout eastern North America using banding data from 7 sites over a 25 year period. Using a mixed linear model, we did not detect any significant trends over time for the total owl count, adult owl count, and juvenile owl count from 1992 to 2017. During the period when all 7 sites were active from 2001 to 2017, trend estimates remained nonsignificant despite showing negative slopes. We confirmed this nonsignificant, negative trend through a similar mixed linear model of NSWO data from Christmas Bird Counts. Our results suggest that NSWO populations across eastern North America have been relatively stable since 1992 throughout their migration and winter ranges and demonstrate the value of standardized banding data for monitoring the regional population status of NSWO.

Migrating animals occur along a continuum from species that spend the nonbreeding season at a fixed location to species that are nomadic during the nonbreeding season, essentially continuously moving. Such variation is likely driven by the economics of territoriality or heterogeneity in the environment. The Snowy Owl (Bubo scandiacus) is known for its complex seasonal movements, and thus an excellent model to test these ideas, as many individuals travel unpredictably along irregular routes during both the breeding and nonbreeding seasons. Two possible explanations for this large variation in the propensity to move are (1) dominance hierarchies in which dominant individuals (adult females in this case) monopolize some key, consistent resources, and move less than subdominants; and (2) habitat heterogeneity in which individuals foraging in rich and less heterogenic environments are less mobile. We analyzed fine-scale telemetry data (global positioning system [GPS]/global system for mobile communication [GSM]) from 50 Snowy Owls tagged in eastern and central North America from 2013 to 2019, comparing space use during the winter period according to sex and age, and to land cover attributes. We used variograms to classify individuals as nomadic (58%) or range-resident (42%), and found that nomadic owls had ten times larger wintering areas than range-resident owls. The frequency of nomadism was similar in socially-dominant adult females, immatures, and males. However, nomadism increased from west to east, and north to south, and was positively associated with the use of water and negatively associated with croplands. We conclude that many individual Snowy Owls in Eastern North America are nomadic during the nonbreeding season and that movement patterns during this time are driven primarily by extrinsic factors, specifically heterogeneity in habitat and prey availability, as opposed to intrinsic factors associated with spacing behavior, such as age and sex.

Background While nest attentiveness plays a critical role in the reproductive success of avian species, nest attentiveness data with high temporal resolution is not available for many species. However, improvements in both video monitoring and temperature logging devices present an opportunity to increase our understanding of this aspect of avian behavior. Methods To investigate nest attentiveness behaviors and evaluate these technologies, we monitored 13 nests across two Common Tern (Sterna hirundo) breeding colonies with a paired video camera - temperature logger approach, while monitoring 63 additional nests with temperature loggers alone. Observations occurred from May to August of 2017 on Poplar (Chesapeake Bay, Maryland, USA) and Skimmer Islands (Isle of Wight Bay, Maryland, USA). We examined data respective to four times of day: Morning (civil dawn‒11:59), Peak (12:00‒16:00), Cooling (16:01‒civil dusk), and Night (civil dusk‒civil dawn). Results While successful nests had mostly short duration off-bouts and maintained consistent nest attentiveness throughout the day, failed nests had dramatic reductions in nest attentiveness during the Cooling and Night periods (p Bubo virginianus). Incubation appeared to ameliorate ambient temperatures during Night, as nests were significantly warmer during Night when birds were on versus off the nest (p p > 0.05), video-monitored nests did have significantly lower clutch sizes (p Conclusions The paired use of iButtons and video cameras enabled a detailed description of the incubation behavior of COTE. However, while promising for future research, the logistical and potential biological complications involved in the use of these methods suggest that careful planning is needed before these devices are utilized to ensure data is collected in a safe and successful manner.

Winter irruptions, defined as irregular massive movement of individuals over large distances, have been linked to food supply. Two hypotheses have been put forward: the “lack-of-food” suggests that a shortage of food forces individuals to leave their regular winter range and the “breeding output” suggests that unusually large food supplies during the preceding breeding season allows production of a large number of offspring dispersing in winter. According to the breeding output hypothesis, irruptive Snowy Owls (Bubo scandiacus (Linnaeus, 1758)) in eastern North America should not exhibit a lower body condition than individuals in regular wintering regions and individuals on the breeding grounds. Additionally, body condition of irruptive individuals should be unrelated to irruption intensity. Although body condition of juveniles was generally lower than that of adults and improved during the winter, we measured a fair body condition in both juvenile and adult irruptive Snowy Owls across North America. The results showed that Snowy Owls are not in a starving state during winter and that body condition of all age classes was not related to winter irruption intensity. Those results support the breeding output hypothesis suggesting that winter irruptions seem to be primarily the result of a large number of offspring produced when food availability on the breeding grounds is high.

Bubo scandiacus (Snowy Owl) is an irregular winter visitor in the northeastern US and southeastern Canada, where winter irruptions occur roughly every 4 years with varying intensity. The consecutive winters of 2013–2014 and 2014–2015 saw unusually large irruptions of Snowy Owls across eastern North American states and provinces and the Great Lakes region. We tracked 34 individuals equipped with high spatial- and temporalresolution GPS–GSM transmitters and obtained data that documented in detail the diverse suite of habitats used by irruptive Snowy Owls overwintering and migrating through the region, from heavily urbanized city centers to open agricultural areas, as well as ice floes drifting on the Great Lakes or concentrating along the shores of the Atlantic Ocean.

Migratory species display a range of migration patterns between irruptive (facultative) to regular (obligate), as a response to different predictability of resources. In the Arctic, snow directly influences resource availability. The causes and consequences of different migration patterns of migratory species as a response to the snow conditions remains however unexplored. Birds migrating to the Arctic are expected to follow the spring snowmelt to optimise their arrival time and select for snow-free areas to maximise prey encounter en-route. Based on large-scale movement data, we compared the migration patterns of three top predator species of the tundra in relation to the spatio-temporal dynamics of snow cover. The snowy owl, an irruptive migrant, the rough-legged buzzard, with an intermediary migration pattern, and the peregrine falcon as a regular migrant, all followed, as expected, the spring snowmelt during their migrations. However, the owl stayed ahead, the buzzard stayed on, and the falcon stayed behind the spatio-temporal peak in snowmelt. Although none of the species avoided snow-covered areas, they presumably used snow presence as a cue to time their arrival at their breeding grounds. We show the importance of environmental cues for species with different migration patterns.

Migratory species display a range of migration patterns between irruptive (facultative) to regular (obligate), as a response to different predictability of resources. In the Arctic, snow directly influences resource availability. The causes and consequences of different migration patterns of migratory species as a response to the snow conditions remains however unexplored. Birds migrating to the Arctic are expected to follow the spring snowmelt to optimise their arrival time and select for snow-free areas to maximise prey encounter en-route. Based on large-scale movement data, we compared the migration patterns of three top predator species of the tundra in relation to the spatio-temporal dynamics of snow cover. The snowy owl, an irruptive migrant, the rough-legged buzzard, with an intermediary migration pattern, and the peregrine falcon as a regular migrant, all followed, as expected, the spring snowmelt during their migrations. However, the owl stayed ahead, the buzzard stayed on, and the falcon stayed behind the spatio-temporal peak in snowmelt. Although none of the species avoided snow-covered areas, they presumably used snow presence as a cue to time their arrival at their breeding grounds. We show the importance of environmental cues for species with different migration patterns.

Nature photonics 14(6), 391 - 397 (2020). doi:10.1038/s41566-020-0607-z, The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created., Published by Nature Publ. Group, London [u.a.]

Many waterbird populations have faced declines over the last century, including the common tern (Sterna hirundo), a waterbird species with a widespread breeding distribution, that has been recently listed as endangered in some habitats of its range. Waterbird monitoring programs exist to track populations through time; however, some of the more intensive approaches require entering colonies and can be disruptive to nesting populations. This paper describes a protocol that utilizes a minimally invasive surveillance system to continuously monitor common tern nesting behavior in typical ground-nesting colonies. The video monitoring system utilizes wireless cameras focused on individual nests as well as over the colony as a whole, and allows for observation without entering the colony. The video system is powered with several 12 V car batteries that are continuously recharged using solar panels. Footage is recorded using a digital video recorder (DVR) connected to a hard drive, which can be replaced when full. The DVR may be placed outside of the colony to reduce disturbance. In this study, 3,624 h of footage recorded over 63 days in weather conditions ranging from 12.8 °C to 35.0 °C produced 3,006 h (83%) of usable behavioral data. The types of data retrieved from the recorded video can vary; we used it to detect external disturbances and measure nesting behavior during incubation. Although the protocol detailed here was designed for ground-nesting waterbirds, the principal system could easily be modified to accommodate alternative scenarios, such as colonial arboreal nesting species, making it widely applicable to a variety of research needs.

Scientific study of raptors often requires the use of a lure to capture individuals for marking or collecting various data and samples. Live lure owls in the genus Bubo are commonly used with mist nets or dho-gazas to trap nesting raptors, but the use of these live lures presents ethical, logistical, and financial challenges. Although owls mounted by taxidermists and mechanical owls have been used in place of a live bird, the success of these types of lures varies widely. We created a more realistic mechanical owl with a greater range of motion than previous models, and then tested the owl on six raptor species in a variety of habitats. For all but one species, capture rates using our mechanical owl were similar to or slightly higher than those reported in studies using live lure owls or previously designed mechanical owls. Time to capture of Northern Goshawks (Accipiter gentilis) was, on average, 8 min faster when using our mechanical owl compared to a live owl. Cost analysis revealed that both the initial expense and long-term maintenance of a mechanical owl were less than that of a live lure owl. Mechanical owls can be a useful tool for capturing raptors. Although there are some drawbacks to using a mechanical owl, our results suggest that mechanical birds are comparable to live lure owls and we believe the benefits of using a mechanical owl often outweigh the costs.

TODD KATZNER,1,2,26 BRIAN W. SMITH,3 TRICIA A. MILLER,4,5 DAVID BRANDES,6 JEFF COOPER,7 MICHAEL LANZONE,5,8 DANIEL BRAUNING,9 CHRISTOPHER FARMER,10 SERGIO HARDING,11 DAVID E. KRAMAR,12 CRAIG KOPPIE,13 CHARLES MAISONNEUVE,14 MARK MARTELL,15 ELIZABETH K. MOJICA,16 CHARLIE TODD,17 JUNIOR A. TREMBLAY,18 MARIA WHEELER,19 DAVID F. BRINKER,20 TONY E. CHUBBS,21 ROLF GUBLER,22 KIERAN O’MALLEY,23 SCOTT MEHUS,24 BRADY PORTER,19 ROBERT P. BROOKS,4 BRYAN D. WATTS,16 AND KEITH L. BILDSTEIN25

Use of ultraviolet (UV) light, which causes porphyrin pigments in feathers of some birds to fluoresce, provides a simple, effective means of distinguishing multiple generations of flight feathers in owls. This permits easier and more accurate classification of age of adult owls. This lighting technique has been used extensively with Barn Owls (Tyto alba) and Northern Saw-whet Owls (Aegolius acadicus) and works well on a variety of owl species at night in the field, and should have wide applicability among owl researchers. The relative ages of the feathers can be easily distinguished by the intensity of fluorescence they exhibit when the ventral surfaces of primaries and secondaries are exposed to UV (black) light. This allows rapid and accurate assessment of molt and, in turn, the assignment of an age classification for the owl.

Serum chemistry panels and complete mineral and heavy metal screens were performed on blood samples from eight adult northern goshawks (Accipiter gentilis) breeding in Pennsylvania. Serum chemistry panels were performed to determine the health status of each bird. Biochemical values measured included serum glucose, sodium, potassium, chloride, magnesium, uric acid, creatine kinase, and aspartate transaminase. Glucose, creatine kinase, and aspartate transaminase values were elevated when compared with published values for northern goshawks and other species of raptors. Complete mineral screens were performed to better document the blood mineral content of northern goshawks. Plasma calcium, copper, iron, magnesium, total phosphorus, potassium, sodium, and zinc levels were determined. Whole blood heavy metal screens were done to evaluate the northern goshawk's exposure to environmental arsenic, cadmium, lead, thallium, and selenium. Arsenic, cadmium, lead, and thallium whole blood levels of less than 0.05 ppm in all birds indicated that the northern goshawks were not being exposed to significant levels of heavy metals in their environment. Whole blood selenium levels of the northern goshawks were above the minimum dietary requirement for avian species (0.130-0.200 ppm) and below published toxic selenium concentrations.

Like many resources in the Chesapeake Bay region of the U.S., many waterbird nesting populations have suffered over the past three to four decades. In this study, historic information for the entire Bay and recent results from the Tangier Sound region were evaluated to illustrate patterns of island erosion and habitat loss for 19 breeding species of waterbirds. Aerial imagery and field data collected in the nesting season were the primary sources of data. From 1993/1994 to 2007/2008, a group of 15 islands in Tangier Sound, Virginia were reduced by 21% in area, as most of their small dunes and associated vegetation and forest cover were lost to increased washovers. Concurrently, nesting American black ducks (Anas rubripes) declined by 66% , wading birds (herons-egrets) by 51%, gulls by 72%, common terns (Sterna hirundo) by 96% and black skimmers (Rynchops niger) by about 70% in this complex. The declines noted at the larger Bay-wide scale suggest that this study area maybe symptomatic of a systemic limitation of nesting habitat for these species. The island losses noted in the Chesapeake have also been noted in other Atlantic U.S. coastal states. Stabilization and/or restoration of at least some of the rapidly eroding islands at key coastal areas are critical to help sustain waterbird communities.

Nest and chick census data gathered from 1975–2005 at all known breeding colonies of Royal (Sterna maxima) and Sandwich (S. sandivicensis) Terns in three mid-Atlantic States are reported. Nest census data were gathered sporadically in North Carolina, Virginia, and Maryland throughout this period. Royal Tern chick counts based on annual banding efforts were obtained in Maryland since 1975 and North Carolina and Virginia since 1977, while Sandwich Tern chick counts date from 1977 in North Carolina and 1980 in Virginia. Royal Tern chick counts show significant annual variation by state, and are positively correlated between North Carolina and Virginia, but negatively correlated between Maryland and both North Carolina and Virginia. Sandwich Tern nest counts showed significant annual variation in North Carolina, as did chick counts in North Carolina and Virginia. These results suggest regional, rather than local, trends in Royal Tern numbers over time. While Royal Tern numbers indicate a gradual dec...

Colonially nesting wading birds (herons, egrets, and ibis) are a highly visible, biologically significant component of the mid-Atlantic coastal avifauna. Populations of these species were decimated by extensive market hunting in the late nineteenth century, recovered, and additional species colonized the region. Herein, we summarize changes in species, numbers of breeding pairs, and colony sites for ten species of wading birds surveyed four times over a 26-year period (1977 to 2003) within the Chesapeake Bay and Atlantic coastal barrier island region. Over the period of surveys, wading bird breeding colonies increased 246% (to 537) and numbers of breeding pairs increased 67% (to 26,589). Expansion among Great Blue Herons (Ardea herodias), Great Egrets (Ardea alba), Yellow-Crowned Night-Herons (Nyctanassa violacea) and Glossy Ibis (Plegadis falcinellus), primarily accounted for the dramatic increase, while declines were recorded for Snowy Egrets (Egretta thula), Cattle Egrets (Bubulcus ibis) and B...

The conservation status of the American Oystercatcher (Haematopus palliatus palliatus) along the Chesapeake Bay, coastal bays, and barrier island shorelines of Maryland and Virginia has been investigated in detail in recent years. The region supports approximately 700 breeding pairs with more than 80% occurring on the east coast of the Delmarva Peninsula and less than 20% occurring along the shorelines of the Chesapeake Bay. The number of breeding pairs in Maryland appears to have been stable or to have increased slightly during the past 20 years. The overall trend of the breeding population in Virginia is less clear, but recent evidence suggests that numbers on the barrier islands are increasing after more than two decades of a declining trend. The coastal bays and barrier islands typically support between 1,500 and 2,000 wintering birds with most occurring on the east coast of the Virginia portion of the Delmarva Peninsula. The shorelines of both states together play an important role in suppor...

Over the past one hundred years, dramatic changes have taken place in populations of colonial-nesting seabirds that breed within Chesapeake Bay and the Maryland-Virginia coastal region. Populations of species that were decimated by extensive market hunting in the late nineteenth century recovered, additional species colonized the region and in the past ten years many species have declined. During 2003, over 72,000 pairs of seabirds of thirteen species bred within the region. Breeding population sizes are presented and population trends evaluated based on benchmark census information from 1977 and regional censuses compiled during 1993 and 2003 by the states of Maryland and Virginia. Since the 1970s, Brown Pelicans (Pelicanus occidentalis) and Double-crested Cormorants (Phalacrocorax auritus) expanded into the region and now represent six percent of the seabird guild. Gull populations have exhibited important changes and have affected other seabird species. Significant population declines have occurred in Black Skimmers (Rynchops niger), Gull-billed Terns (Sterna nilotica), Royal Terns (Sterna maxima), and Common Terns (Sterna hirundo). Since 1993, populations of ten of thirteen seabird species have declined, many significantly. Conservation challenges for seabird species in the region include: 1) habitat change and loss as a result of sea-level rise, 2) increasing mammalian predator populations, 3) competition for colony sites, 4) human infrastructure conflicts, and 5) changing fisheries populations and harvest. Conserving and managing colonial-nesting seabirds in the coming decades as the human population continues to increase in the mid-Atlantic region will present significant challenges to future generations.

The objective of this study was to characterize the behavior of a groundwater contaminant (trichloroethene) plume after implementation of a source-containment operation at a site in Arizona. The plume resides in a quasi three-layer system comprising a sand/gravel unit bounded on the top and bottom by relatively thick silty clayey layers. The system was monitored for 60 months beginning at start-up in 2007 to measure the change in contaminant concentrations within the plume, the change in plume area, the mass of contaminant removed, and the integrated contaminant mass discharge. Concentrations of trichloroethene in groundwater pumped from the plume extraction wells have declined significantly over the course of operation, as have concentrations for groundwater sampled from 40 monitoring wells located within the plume. The total contaminant mass discharge associated with operation of the plume extraction wells peaked at 0.23 kg/d, decreased significantly within one year, and thereafter began an asymptotic decline to a current value of approximately 0.03 kg/d. Despite an 87% reduction in contaminant mass and a comparable 87% reduction in contaminant mass discharge for the plume, the spatial area encompassed by the plume has decreased by only approximately 50%. This is much less than would be anticipated based on ideal flushing and mass-removal behavior. Simulations produced with a simplified 3-D numerical model matched reasonably well to the measured data. The results of the study suggest that permeability heterogeneity, back diffusion, hydraulic factors associated with the specific well field system, and residual discharge from the source zone are all contributing to the observed persistence of the plume, as well as the asymptotic behavior currently observed for mass removal and for the reduction in contaminant mass discharge.

We quantified home range size and habitat selection of seven female Northern Saw-whet Owls (Aegolius acadicus) on Assateague Island, Maryland, during the winters of 1996 and 1997. Home range size (95% fixed kernel) was 103.5 ha (± 50.3 SE). Home range size increased with time spent radio tracking as biweekly home ranges were smaller than those calculated for longer time periods. Home ranges often overlapped in time and space and in one instance the home range for one owl was completely within that of another owl. Northern Saw-whet Owls used primarily pine woods and shrub swamp habitats, with pine woods used more often than any other habitat type and significantly more than expected based on habitat availability.

The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower permeability strata adjacent to a sand/gravel unit in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for nine years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection.. These results demonstrate successful creation of a long-term, dissolved-phase reactive-treatment zone that reduced mass discharge from the source. This project illustrates the application of in-situ chemical oxidation as a persistent dissolved-phase reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater.

We characterized 30 diurnal roost sites of five radio-tagged Northern Saw-whet Owls (Aegolius acadicus) in the winters of 1996–1997 on Assateague Island, Maryland and found they preferred thick cover at roost sites. Roosts occurred most often in loblolly pine forest (Pinus taeda) and shrub swamps dominated by wax myrtle (Myrica cerifera). Vegetation was measured at paired roosts and random sites in similar habitats. Distance to nearest tree and average canopy height were significantly lower at roost sites than random sites. Numbers of stems larger than 2.5 cm diameter at breast height (dbh), stems smaller than 2.5 cm dbh, and roost tree dbh were larger at roost sites. Roost height, canopy cover, canopy height, shrub height, and ground cover differed significantly between pine and shrub swamp roosts, although cover above and below the roost site were similar. Higher densities of stems and shorter distances to the nearest tree at roost sites compared to random sites indicated that owls chose sites ...

This paper presents the concept of the new FEL facility at the 1.5 GeV electron storage ring DELTA, currently under construction at the University of Dortmund. Furthermore, detailed information about the accelerator itself and the first FEL experiment (FELICITA I) are given.

Complementary and alternative medicines (CAM) are commonly consumed by patients before surgery, though CAM use seldom is revealed during preoperative assessment. Many alternative medicines may interact with anesthetic drugs to inhibit coagulation, precipitating unnecessary surgical blood loss. This article reviews research of herbs and dietary supplements that have effects on the coagulation process. Knowledge of specific pharmacodynamic mechanisms of action is essential to determine herbs and dietary supplements that may interact with drugs that alter the hemostatic process. Further integrative research, education of practitioners, and greater patient communication are necessary to prevent herb-supplement drug interactions that may inhibit coagulation in surgical patients.

In May 93 the operation of DORIS for high energy physics was discontinued and the ring became a dedicated source for synchrotron radiation operated at 4.5 GeV. Meanwhile a multibunch feedback system to control beam instabilities had been installed and positrons were stored instead of electrons. The resulting improvements and also the present status are described by discussing some important parameters and their limitations. These parameters include the beam lifetime, the maximum stored currents, the number of bunches, the beam dimensions and aperture, orbit distortions, position control of the photon beams, the reliability and the influence of the 10 insertion devices on the stored beam.

A lead-copper calorimeter in liquid argon and an iron streamer tube calorimeter acting as a tail catcher have been tested with pions in the energy range of 30–230 GeV. Results are given on the energy resolution, on sampling fluctuations and on the space resolution of the liquid argon calorimeter. For the combined system an energy resolution of σ E ≈ 0.5 √E is obtained applying software weighting techniques and corrections for the dead material between the two calorimeters on an event to event basis. The remaining tails in the energy distributions are discussed.