To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The aim of the present study is to use the syndemic framework to investigate the risk of contracting HIV in the US population. Cross-sectional analyses are from The National Health and Nutrition Examination Survey. We extracted and aggregated data on HIV antibody test, socio-demographic characteristics, alcohol use, drug use, depression, sexual behaviours and sexually transmitted diseases from cycle 2009–2010 to 2015–2016. We carried out weighted regression among young adults (20–39 years) and adults (40–59 years) separately. In total, 5230 men and 5794 women aged 20–59 years were included in the present analyses. In total, 0.8% men and 0.2% women were tested HIV-positive. Each increasing HIV risk behaviour was associated with elevated odds of being tested HIV-positive (1.15, 95% CI 1.15–1.15) among young adults and adults (1.61, 95% CI 1.61–1.61). Multi-faceted, community-based interventions are urgently required to reduce the incidence of HIV in the USA.
Leaf colour characteristics of 730 sweetpotato, Ipomoea batatas (L.) Lam. (Convolvulaceae), plant introduction (PI) accessions from the USDA sweetpotato germplasm collection were evaluated during 2012–2014. Colorimetry data for the abaxial and adaxial leaf surfaces were recorded using a tristimulus colorimeter and the CIE 1976 L*a*b* and CIE L*C*h* colour spaces. Most accessions (725 of 730 PIs) had dark-to-medium green leaves, but two PIs had totally purple leaves, and three PIs had yellow or yellow-green (chartreuse) leaves. For mature, field-grown green leaves, values for the red-green coordinate (a*) averaged −12.4 for the adaxial and −10.4 for the abaxial leaf surface. Values for the blue-yellow coordinate (b*) averaged 17.2 for the adaxial and 17.3 for the abaxial leaf surface. Hue angle (h*) for green leaves averaged 120.9° for the adaxial and 126.2° for the abaxial leaf surface. Colour saturation (Chroma, C*) averaged 21.3 for the adaxial and 20.2 for the abaxial leaf surface. Lightness (L*) averaged 35.4 for the adaxial and 47.2 for the abaxial leaf surface of green leaves. Late in the season, over one-half (53.9%) of the 730 PIs showed some level of purple pigmentation in the leaf lamina. Late-season purple leaves were collected and colour coordinates were recorded for 118 PIs grown in the field. For purple leaves, values for a*, b*, C*, L* and h* averaged 2.3, 6.2, 7.9, 28.2 and 64.4° for the adaxial surface and −1.0, 12.7, 13.9, 43.1 and 87.0° for the abaxial leaf surface, respectively.
Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.
SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.
SPICA instruments offer spectral resolving power ranging from R ~50 through 11 000 in the 17–230 μm domain and R ~28.000 spectroscopy between 12 and 18 μm. SPICA will provide efficient 30–37 μm broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 μm. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of ~5 × 10−20 W m−2 (5σ/1 h)—over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.
Plant secondary metabolites (PSM) are widely known for their antinutritional properties; their excessive consumption can detrimentally affect herbivore health and, in some cases, survival. However, a growing body of evidence is suggesting that some classes of PSM may also have some positive effects on herbivores. Such positive effects include the antiparasitic properties of certain PSM and their beneficial consequences on the herbivore's fitness. One of the better-exploited classes of PSM that have been reported with anthelmintic properties is that of the condensed tannins. The consumption of moderate concentrations of condensed tannins has resulted in reduced level of parasitism in sheep and other ruminants. In this paper we discuss the conditions that should be met in order for the positive anthelmintic properties of PSM, and condensed tannins in particular, to be beneficial for parasitised sheep. We also examine whether PSM could have a role in controlling parasitism in ruminants and point out the future research needed to achieve an efficient use of PSM for parasite control.
The Neotoma Paleoecology Database is a community-curated data resource that supports interdisciplinary global change research by enabling broad-scale studies of taxon and community diversity, distributions, and dynamics during the large environmental changes of the past. By consolidating many kinds of data into a common repository, Neotoma lowers costs of paleodata management, makes paleoecological data openly available, and offers a high-quality, curated resource. Neotoma’s distributed scientific governance model is flexible and scalable, with many open pathways for participation by new members, data contributors, stewards, and research communities. The Neotoma data model supports, or can be extended to support, any kind of paleoecological or paleoenvironmental data from sedimentary archives. Data additions to Neotoma are growing and now include >3.8 million observations, >17,000 datasets, and >9200 sites. Dataset types currently include fossil pollen, vertebrates, diatoms, ostracodes, macroinvertebrates, plant macrofossils, insects, testate amoebae, geochronological data, and the recently added organic biomarkers, stable isotopes, and specimen-level data. Multiple avenues exist to obtain Neotoma data, including the Explorer map-based interface, an application programming interface, the neotoma R package, and digital object identifiers. As the volume and variety of scientific data grow, community-curated data resources such as Neotoma have become foundational infrastructure for big data science.
Sainfoin (Onobrychis viciifolia) is a Mediterranean forage rich in tannins, which has been shown to reduce the faecal excretion of nematode parasites in goats, when offered as hay supplement (Paolini et al, 2003). The use of conserved forages for parasite control may be preferred when either the climatic or agronomic conditions are not appropriate for the grazing of such forages. The aim of this experiment was to investigate whether the consumption of sainfoin hay could reduce the viability and fecundity of adult gastrointestinal parasites, when offered to parasitised sheep at different time points during the course of a parasitic challenge.
The potential antiparasitic effects of chicory (Cichorium intybus ) are currently investigated as an alternative means to control parasitism in organic sheep production systems. Previous studies showed that parasitised lambs grazing on parasite-clean chicory swards had improved growth and lower faecal egg counts (FEC) compared to those grazing on parasite-clean grass pastures (Athanasiadou et al, 2004). The objective of this experiment was to investigate whether chicory can have a role as a potential means to control parasitism in lactating ewes and their lambs grazing on previously parasite contaminated pastures.
Bioactive forages such as chicory (Cichorium intybus) or tanniferous legume sulla (Hedysarum coronarium), have been reported to lower the parasite intensities or faecal egg counts (FEC) of parasitised ruminants (Waller and Thamsborg, 2004). To our knowledge, there is no report studying the effects of these forages on established worm populations when grazed in combination. This knowledge could guide us towards optimum grazing management using special forage species as de-worming paddocks. The aim of the present study was to use the bioactive forages alone or in combination for a short period to test their effects on established T. circumcincta adult population in sheep. The tested bioactive forages were chicory and sulla, with grass/clover (Lolium perenne/Trifolium repens) providing the control forage.
The deposition of dung on pasture may create a trade-off between the benefit of increased nutrient intake due to the leaching of nutrients and the risk of parasitism due to migration of helminth parasite larvae (Sykes, 1987), from the faeces to the sward. Physiological state can affect herbivore foraging decisions in relation to this trade-off. Our objectives were to determine whether such a trade-off exists in a grazing situation for sheep and whether level of feeding motivation and parasitic status affect the grazing behaviour of sheep faced with this trade-off.
Texel x Greyface lambs were presented pairs of swards (36 x 21cm) which varied in nitrogen content (high=N+; low=N-) and level of contamination with faeces from sheep infected with Ostertagia circumcincta (Ost.) (20g faeces per sward=F+; no faeces=F-) and allowed to graze for short periods (60 bites or ten minutes). We defined ‘taking the trade-off’ as taking more bites from an N+F+ sward compared to an N-F- sward, when presented together as a choice.
Parasitised sheep consuming forages high in condensed tannins (CT) show lower faecal egg counts (FEC) and total worm burden (TWB) compared to those consuming CT free forages (Niezen et al., 1998). This may be due to an indirect effect of CT, through an increase in protein availability; extra protein could improve the host’s ability to mount an effective response towards gastrointestinal parasites, during the expression of the immunity (Coop and Kyriazakis, 1999). However, CT have been also shown to have a direct anthelmintic effect on adult Trichostrongylus colubriformis (intestinal nematode), when they were administered for a short period (Athanasiadou et al., 2000). The objectives of this experiment were i) to elucidate the effects of a continuous intake of CT during the development of a T.colubriformis infection and ii) to test whether these effects are dose dependent.
It has been suggested that periparturient breakdown of immunity to parasites (BIP) has a nutritional basis (Coop and Kyriazakis, 1999). In support of this hypothesis, recent studies have shown that an increased supply of metabolizable protein (MP) reduces the magnitude of periparturient BIP in sheep (Houdijk et al., 2001). Improved MP supply to ewes, infected with gastrointestinal nematodes, has been associated with reduced nematode egg excretion and smaller worm burdens. These immunity indicators may differ in their sensitivity to changes in MP supply. This hypothesis has been addressed in the current doses-response experiment, which also allowed us to estimate the MP requirements of parasitized, lactating, twin-rearing ewes. The latter can be expected to be larger than those of non-parasitized ewes, due to MP requirements for mounting an immune response and for replenishing protein losses.
Under organic regulations, farmers in the uk are allowed to drench periparturient ewes with an anthelmintic drug before returning them to pasture. Although such practice is against the principles of organic farming, it is allowed as it reduces parasite contamination of the pastures and consequently reduces the risk of parasitism in growing lambs. Alternatives to control parasitism, which do not jeopardise the health and welfare of grazing ruminants and also minimise anthelmintic input in organic systems are currently being investigated. Grazing bioactive forages, such as chicory has resulted in a lower level of parasitism than sheep grazing on grass/clover pastures (Marley et al, 2003). The objective of this experiment was to investigate whether grazing on chicory can affect the epidemiology of gastrointestinal parasitism, so that control of sub-clinical parasitism could be achieved without the use of anthelmintics.
A nutrient partitioning framework has been developed to account for host nutrition-parasite interactions in mammals (Coop and Kyriazakis, 1999). The framework puts forward a nutritional basis for the occurrence of the periparturient relaxation of immunity (PPRI) to gastrointestinal parasites in sheep. The PPRI would be expected to occur because it is proposed that the reproductive effort has a higher partial priority than the immune functions when hosts are given access to scarce nutrient resources, such as metabolizable protein (MP). This would imply that i) immune functions towards parasites will benefit from an increased MP supply, and that ii) the degree of the PPRI depends on the level of reproductive effort. We studied these predictions by comparing performance and resistance in parasitized twin- and single-rearing ewes, which were offered increasing amounts of MP.
One major consequence of the presence of the nematode parasites in the gastrointestinal tract (GIT) of ruminants appears to be an elevated flow of endogenous N component from the small intestine, leading to adverse changes in host productivity (MacRae, 1993). However, many of these aspects have remained speculative because of a lack of appropriate methodology to quantify the influence of parasites on GIT protein metabolism. In the present study oxidation of leucine sequestrated from arterial blood and digesta-derived leucine during “first pass” metabolism in the GIT of lambs subjected to subclinical T. colubriformis infection were quantified directly, using trans-organ catheterisation procedures coupled with stable isotope tracer kinetics.
Nematodes are a particular challenge to animal health and productivity in organic sheep systems, where the prophyllactic use of anthelmintic is prohibited. The peri-parturient rise in faecal egg output, a consequence of relaxation of host immunity in late pregnancy and early lactation, is potentially a key factor in the epidemiology of parasitic gastro-enteritis on organic sheep farms. Coop and Kyriazakis (1999) developed a hypothesis to explain the relationship between nutrition and periparturient breakdown of immunity to parasites, and there is now an increasing body of evidence for the involvement of dietary protein (Houdijk et al 2001). The objective of this study was to test this hypothesis in organically managed ewes carrying a mixed, naturally acquired infection, grazing on grass/clover in early lactation, and to examine the potential for a nutritional approach to parasite control in commercial practice.
Body reserves can be regarded as sources of nutrients at times of scarce nutrient intake. It has been suggested that the latter is responsible for the periparturient breakdown in immunity to parasites (BIP), since most scarce nutrients are expected to be allocated to the prioritised reproductive effort (Coop and Kyriazakis, 1999). Nutrient supply from body reserves may partly overcome scarce nutrient intake and, as a consequence, can be expected to affect BIP. It has been shown that an increased supply of dietary metabolizable protein (MP), but not of metabolizable energy (ME), reduces periparturient BIP (Donaldson et al., 1998). Therefore, we tested the hypotheses that body protein reserves, but not body fat reserves, affect BIP and its relationship with dietary MP supply in periparturient ewes.