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We describe an ultra-wide-bandwidth, low-frequency receiver recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (
), the system temperature is approximately 22 K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver, including its astronomical objectives, as well as the feed, receiver, digitiser, and signal processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified, including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration, and timing stability.
Cauterisation techniques are commonly used and widely accepted for the management of epistaxis. This review assesses which methods of intranasal cautery should be endorsed as optimum treatment on the basis of benefits, risks, patient tolerance and economic assessment.
A systematic review of the literature was performed using a standardised methodology and search strategy.
Eight studies were identified: seven prospective controlled trials and one randomised controlled trial. Pooling of data was possible from 3 studies, yielding a total of 830 patients. Significantly lower re-bleed rates were identified (p < 0.01) using electrocautery (14.5 per cent) when compared to chemical cautery (35.1 per cent). No evidence suggested that electrocautery was associated with more adverse events or discomfort. Limited evidence supported the use of a vasoconstrictor agent and operating microscope during the procedure. The included studies had considerable heterogeneity in terms of design and outcome measures.
Consistent evidence suggests that electrocautery has higher success rates than chemical cautery, and is not associated with increased complications or patient discomfort. Lower quality evidence suggests that electrocautery reduces costs and duration of hospital stay.
Acute kidney injury after cardiac surgery is a frequent and serious complication among children with congenital heart disease (CHD) and adults with acquired heart disease; however, the significance of kidney injury in adults after congenital heart surgery is unknown. The primary objective of this study was to determine the incidence of acute kidney injury after surgery for adult CHD. Secondary objectives included determination of risk factors and associations with clinical outcomes.
This single-centre, retrospective cohort study was performed in a quaternary cardiovascular ICU in a paediatric hospital including all consecutive patients ⩾18 years between 2010 and 2013.
Data from 118 patients with a median age of 29 years undergoing cardiac surgery were analysed. Using Kidney Disease: Improving Global Outcome creatinine criteria, 36% of patients developed kidney injury, with 5% being moderate to severe (stage 2/3). Among higher-complexity surgeries, incidence was 59%. Age ⩾35 years, preoperative left ventricular dysfunction, preoperative arrhythmia, longer bypass time, higher Risk Adjustment for Congenital Heart Surgery-1 category, and perioperative vancomycin use were significant risk factors for kidney injury development. In multivariable analysis, age ⩾35 years and vancomycin use were significant predictors. Those with kidney injury were more likely to have prolonged duration of mechanical ventilation and cardiovascular ICU stay in the univariable regression analysis.
We demonstrated that acute kidney injury is a frequent complication in adults after surgery for CHD and is associated with poor outcomes. Risk factors for development were identified but largely not modifiable. Further investigation within this cohort is necessary to better understand the problem of kidney injury.
Suicide is a devastating public health problem and very few biological treatments have been found to be effective for quickly reducing the intensity of suicidal ideation (SI). We have previously shown that a single dose of ketamine, a glutamate N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with a rapid reduction in depressive symptom severity and SI in patients with treatment-resistant depression.
We conducted a randomized, controlled trial of ketamine in patients with mood and anxiety spectrum disorders who presented with clinically significant SI (n = 24). Patients received a single infusion of ketamine or midazolam (as an active placebo) in addition to standard of care. SI measured using the Beck Scale for Suicidal Ideation (BSI) 24 h post-treatment represented the primary outcome. Secondary outcomes included the Montgomery–Asberg Depression Rating Scale – Suicidal Ideation (MADRS-SI) score at 24 h and additional measures beyond the 24-h time-point.
The intervention was well tolerated and no dropouts occurred during the primary 7-day assessment period. BSI score was not different between the treatment groups at 24 h (p = 0.32); however, a significant difference emerged at 48 h (p = 0.047). MADRS-SI score was lower in the ketamine group compared to midazolam group at 24 h (p = 0.05). The treatment effect was no longer significant at the end of the 7-day assessment period.
The current findings provide initial support for the safety and tolerability of ketamine as an intervention for SI in patients who are at elevated risk for suicidal behavior. Larger, well-powered studies are warranted.
Using in situ data from 2011 and 2013, we evaluate the ability of CryoSat-2 (CS-2) to retrieve sea-ice freeboard over fast ice in McMurdo Sound. This provides the first systematic validation of CS-2 in the coastal Antarctic and offers insight into the assumptions currently used to process CS-2 data. European Space Agency Level 2 (ESAL2) data are compared with results of a Waveform Fitting (WfF) procedure and a Threshold-First-Maximum-Retracker-Algorithm employed at 40% (TFMRA40). A supervised freeboard retrieval procedure is used to reduce errors associated with sea surface height identification and radar velocity in snow. We find ESAL2 freeboards located between the ice and snow freeboard rather than the frequently assumed snow/ice interface. WfF is within 0.04 m of the ice freeboard but is influenced by variable snow conditions causing increased radar backscatter from the air/snow interface. Given such snow conditions and additional uncertainties in sea surface height identification, a positive bias of 0.14 m away from the ice freeboard is observed. TFMRA40 freeboards are within 0.03 m of the snow freeboard. The separation of freeboard estimates is primarily driven by the different assumptions of each retracker, although waveform alteration by variations in snow properties and surface roughness is evident. Techniques are amended where necessary, and automatic freeboard retrieval procedures for ESAL2, WfF and TFMRA40 are presented. CS-2 detects annual fast-ice freeboard trends using all three automatic procedures that are in line with known sea-ice growth rates in the region.
The study of life histories involves the full span of life, from egg or sperm through reproduction and death. The ways in which individuals maximize progeny production and survival are about as diverse as the populations and species themselves. Research interest in life history is therefore strongly comparative, looking at the variation in life-history characteristics within populations, within species and among related species. As with ecology in general, we search for patterns in nature and develop hypotheses and theories, which account for the trends that we observe, and prompt new observations in a cycle of efforts to refine knowledge.
Understanding of life histories is fundamental to insect ecology, and we have covered many examples of life-history studies already in this book, and more will follow. Behavioral traits that promote fitness were covered in Chapter 2, and the evolution of life histories of social insects was discussed in Chapter 3. Chapter 4 included discussion of wing polymorphism in planthoppers (Figure 4.5), and jousting and territoriality of Pemphigus aphids (Figure 4.11). Density effects on planthopper fecundity and wing polymorphism were involved with competition (Chapter 5, Figure 5.8), and egg-laying schedules of a fruit fly were described in Chapter 9 (Figure 9.10). We noted also in Chapter 9 the differences between pro-ovigenic and synovigenic egg production, and the marked differences in survival of progeny portrayed in survivorship curves. In Chapter 6 different strategies of yucca moths were noted among true pollinators and two classes of cheaters (Figure 6.14). We also saw divergence of life-history types in scarab beetles (Figure 6.16) and the constraints on ovariole number and fecundity of parasitoid wasps and flies (Figure 8.4). Indeed, the study of life-history traits runs throughout ecology, and this is how it should be, because understanding the evolution of whole life histories is at the heart of understanding insects, and the evolutionary pathways along which they have traveled. This point is taken up again in the last section of this chapter on applications.
Everybody is conscious of insects, and even concerned about them. In fact, we each have an ecological relationship with their kind. We share our houses and gardens with them, our walks and picnics, and our adventures. So should we not understand them? Their richness in species and interactions, their beauty and behavioral intricacy, all enrich our lives if we understand who they are, and what they are doing. Therefore, the ecology of insects is for everybody.
Eisner (2003, p. 1), in his latest book, For Love of Insects, starts by writing that “This book is about the thrill of discovery.” And, Wilson (1994, p. 191), in his autobiographical, Naturalist, advised, “Love the organisms for themselves first, then strain for general explanations, and, with good fortune, discoveries will follow. If they don't, the love and the pleasure will have been enough.” Here is sound advice from two of the greatest practitioners of entomology and ecology, for discovery is thrilling, and the deeper the fascination one develops, the greater will be the discoveries that follow.
This book concludes with discussions on the broadest biological patterns we can observe on this Earth, and the reasons for their existence. We also examine smaller scales of variation that would be seen on the landscape and ecosystem levels. In doing so we pick up various topics discussed in previous chapters, such as the roles of time and space as influences on species richness, and expand this view to the global level, showing that the same factors remain important as we scale up our perspective to interactions on Earth. We also look at the paleobiological record again, as we did in Chapter 1 to note the long evolutionary history of insects, but in this section we examine the record for clues on what might be expected as global changes occur, and if predictions are possible.
All natural populations fluctuate: they are dynamic. introduced the concepts of population growth and regulation. How and why populations change are the subjects of this chapter. Population dynamics has been of major concern in insect ecology for at least two reasons. First, ecology has been defined as the study of the distribution and abundance of species (Andrewartha and Birch 1954, Krebs 1972). Since the study of population dynamics must include both changes in numbers over time and over the landscape, the subject acts as a central theme in ecology: a unifying concept that permeates the science. It is therefore critical to the conceptual development of ecology. Second, the subject is directly applicable to problems in managing plants as resources for humans, in agriculture, horticulture and forestry. In fact, the need to monitor and understand insect damage to crops and forests was a major motivation for the beginnings of ecology and the study of population dynamics. Other applications include the study of vectors of diseases, such as mosquitoes, pests of cattle such as ticks and screwworm, and vectors of plant pathogens. For these reasons the field of insect population dynamics has played a prominent role in the development of basic ecology and in the understanding and management of serious pests over the landscape.
First we will examine major patterns in populations and then move on to mechanisms that may be driving these patterns, including abiotic and biotic influences, and complex interactions involving both. We also consider the question of how common eruptive species are, how frequently eruptions occur, and whether outbreaks result from human interference with natural dynamics. We note that long-term studies are essential in deciphering the reasons for population change, but many potential influences need to be investigated. Bottom-up effects from plants, top-down effects from natural enemies and lateral effects all need attention. Spatial distribution of populations is also important in a fragmented landscape, covered by the field of metapopulation dynamics. Population dynamics is a field of wide application for understanding pest species, epidemiology, biological control and conservation, all requiring information for planning and management.
Behavior links the organism to its environment. At every moment of the day and night behavioral responses to environmental cues, and internal drives, guide an individual through its often perilous existence. Behavior determines success or failure in the efforts to reproduce. Discovering the many cues that insects use to inform them of their environment, and their responses to these stimuli, is an ongoing pursuit of behavioral ecologists. This is because insects can be much more specialized than humans in the cues employed to locate food, and cues that stimulate feeding. Indeed, the ways in which they relate to their surroundings is often notably different from we humans. As a result, behavioral ecology is a broad and fascinating subject which reaches well beyond this section of the book, into on species interactions and other parts of the book.