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As a label for a distinct category of life, “living fossil” is controversial. The term has multiple definitions, and it is unclear whether the label can be genuinely used to delimit biodiversity. Even taking a purely phylogenetic perspective in which a proxy for the living fossil is evolutionary distinctness (ED), an inconsistency arises: Does it refer to “dead-end” lineages doomed to extinction or “panchronic” lineages that survive through multiple epochs? Recent tree-growth model studies indicate that speciation rates must have been unequally distributed among species in the past to produce the shape of the tree of life. Although an uneven distribution of speciation rates may create the possibility for a distinct group of living fossil lineages, such a grouping could only be considered genuine if extinction rates also show a consistent pattern, be it indicative of dead-end or panchronic lineages. To determine whether extinction rates also show an unequal distribution, we developed a tree-growth model in which the probability of speciation and extinction is a function of a tip’s ED. We simulated thousands of trees in which the ED function for a tip is randomly and independently determined for speciation and extinction rates. We find that simulations in which the most evolutionarily distinct tips have lower rates of speciation and extinction produce phylogenetic trees closest in shape to empirical trees. This implies that a distinct set of lineages with reduced rates of diversification, indicative of a panchronic definition, is required to create the shape of the tree of life.
Official suicide statistics for England are based on deaths given suicide verdicts and most cases given an open verdict following a coroner's inquest. Previous research indicates that some deaths given accidental verdicts are considered to be suicides by clinicians. Changes in coroners' use of different verdicts may bias suicide trend estimates. We investigated whether suicide trends may be over- or underestimated when they are based on deaths given suicide and open verdicts.
Possible suicides assessed by 12 English coroners in 1990/91, 1998 and 2005 and assigned open, accident/misadventure or narrative verdicts were rated by three experienced suicide researchers according to the likelihood that they were suicides. Details of all suicide verdicts given by these coroners were also recorded.
In 1990/91, 72.0% of researcher-defined suicides received a suicide verdict from the coroner, this decreased to 65.4% in 2005 (ptrend < 0.01); equivalent figures for combined suicide and open verdicts were 95.4% (1990/91) and 86.7% (2005). Researcher-defined suicides with a verdict of accident/misadventure doubled over that period, from 4.6% to 9.1% (p < 0.01). Narrative verdict cases rose from zero in 1990/91 to 25 in 2005 (4.2% of researcher-defined suicides that year). In 1998 and 2005, 50.0% of the medicine poisoning deaths given accidental/misadventure verdicts were rated as suicide by the researchers.
Between 1990/91 and 2005, the proportion of researcher-defined suicides given a suicide verdict by coroners decreased, largely due to an increased use of accident/misadventure verdicts, particularly for deaths involving poisoning. Consideration should be given to the inclusion of ‘accidental’ deaths by poisoning with medicines in the statistics available for monitoring suicides rates.
We describe three new species of fruit flies (Tephritidae: Tephritinae) (Gymnocarena defoeisp. nov. and Gymnocarenanorrbomisp. nov., from eastern North America and Gymnocarena monzonisp. nov. from Guatemala) and redescribe Gymnocarena mississippiensis Norrbom. Gymnocarena monzoni is the first Gymnocarena species to be recorded from Guatemala. This brings the total number of named species in this genus to 19. New larval host plant (Asteraceae) records for Gymnocarena include Verbesina helianthoides Michx. for G. mississippiensis and G. norrbomi, Verbesinaalternifolia (L.) Britton ex Kearney for G. norrbomi, and Viguiera cordata (Hook. and Arn.) D'Arcy for G. monzoni. The latter represents the first record for Gymnocarena in Viguiera Kunth. Gymnocarena larvae were also recorded from Verbesina virginica L. but not identified to species. A revised key to the known species of Gymnocarena and additional information on larval host plants and biology are provided.
Several theories have posited a common internalizing factor to help account for the relationship between mood and anxiety disorders. These disorders are often co-morbid and strongly covary. Other theories and data suggest that personality traits may account, at least in part, for co-morbidity between depression and anxiety. The present study examined the relationship between neuroticism and an internalizing dimension common to mood and anxiety disorders.
A sample of ethnically diverse adolescents (n=621) completed self-report and peer-report measures of neuroticism. Participants also completed the Structured Clinical Interview for DSM-IV (SCID).
Structural equation modeling showed that a single internalizing factor was common to lifetime diagnosis of mood and anxiety disorders, and this internalizing factor was strongly correlated with neuroticism. Neuroticism had a stronger correlation with an internalizing factor (r=0.98) than with a substance use factor (r=0.29). Therefore, neuroticism showed both convergent and discriminant validity.
These results provide further evidence that neuroticism is a necessary factor in structural theories of mood and anxiety disorders. In this study, the correlation between internalizing psychopathology and neuroticism approached 1.0, suggesting that neuroticism may be the core of internalizing psychopathology. Future studies are needed to examine this possibility in other populations, and to replicate our findings.
The design of metals and alloys resistant to radiation damage involves the physics of
electronic excitations and the creation of defects and microstructure. During irradiation damage of metals by high energy particles, energy is exchanged between ions and electrons. Such “non-adiabatic” processes violate the Born-Oppenheimer approximation, on which all conservative classical interatomic potentials rest. By treating the electrons of a metal explicitly and quantum mechanically we are able to explore the influence of electronic excitations on the ionic motion during irradiation damage. Simple theories suggest that moving ions should feel a damping force proportional to their velocity and directly opposed to it. In contrast, our simulations of a forced oscillating ion have revealed the full complexity of this force: in reality it is anisotropic and dependent on the ion velocity and local atomic environment. A large set of collision cascade simulations has allowed us to explore the form of the damping force further. We have a means of testing various schemes in the literature for incorporating such a force within molecular dynamics (MD) against our semi-classical evolution with explicitly modelled electrons. We find that a model in which the damping force is dependent upon the local electron density is superior to a simple fixed damping model. We also find that applying a lower kinetic energy cut-off for the damping force results in a worse model. A detailed examination of the nature of the forces reveals that there is much scope for further improving the electronic force models within MD.
We consider the reinterpretation of Bethia by Bassett et al. (2008) to be flawed in several regards. Details of the pedicle rootlets and wrinkles strongly imply a soft-tissue structure rather than calcified sheath. The ornament is unusual, but equally so under either an orthide or a plectambonitoidean model. The reinterpretation of the ‘deltial plates’ as ‘chilidial plates’ is likely correct, but argues against a plectambonitoidean affinity by implying that the pedicle emerges between the valves. Other arguments presented in favour of a plectambonitoidean affinity are also discussed; we consider them unpersuasive. Finally, we contend that Bethia is sufficiently well characterised to deserve a taxonomic name.
Covering an area of 177,000 hectares, the region known within Belize as the Chiquibul Forest comprises the country's largest forest reserve and includes the Chiquibul Forest Reserve, the Chiquibul National Park and the Caracol Archaeological Reserve. Based on 7047 herbarium and live collections, a checklist of 1355 species of vascular plant is presented for this area, of which 87 species are believed to be new records for the country. Of the 41 species of plant known to be endemic to Belize, four have been recorded within the Chiquibul, and 12 species are listed in The World Conservation Union (IUCN) 2006 Red List of Threatened Species. Although the Chiquibul Forest has been relatively well collected, there are geographical biases in botanical sampling which have focused historically primarily on the limestone forests of the Chiquibul Forest Reserve. A brief review of the collecting history of the Chiquibul is provided, and recommendations are given on where future collecting efforts may best be focused. The Chiquibul Forest is shown to be a significant regional centre of plant diversity and an important component of the Mesoamerican Biological Corridor.
A vaccination programme offering hepatitis B (HBV) vaccine at reception into prison has been introduced into selected prisons in England and Wales. Over the coming years it is anticipated this vaccination programme will be extended. A model has been developed to assess the potential impact of the programme on the vaccination coverage of prisoners, ex-prisoners, and injecting drug users (IDUs). Under a range of coverage scenarios, the model predicts the change over time in the vaccination status of new entrants to prison, current prisoners and IDUs in the community. The model predicts that at baseline in 2012 57% of the IDU population will be vaccinated with up to 72% being vaccinated depending on the vaccination scenario implemented. These results are sensitive to the size of the IDU population in England and Wales and the average time served by an IDU during each prison visit. IDUs that do not receive HBV vaccine in the community are at increased risk from HBV infection. The HBV vaccination programme in prisons is an effective way of vaccinating this hard-to-reach population although vaccination coverage on prison reception must be increased to achieve this.
A significant proportion of the grass silage fed to lactating dairy cows may be of only modest quality due either to delayed harvesting and/or poor ensiling conditions. In such situations, both total feed intake and milk production are likely to be compromised with the consequent need to feed more concentrates. Part of this effect is considered to be due to the development of a solid mass of digesta in the rumen, with loss of the normal layered or biphasic stratification of rumen contents. Under such conditions, rumen motility, rate of forage digestion and hence voluntary feed intake will be compromised. Mertens (1997) stressed that chemical definition of dietary fibre such as neutral- (NDF) or acid-detergent (ADF) fibre content was an inadequate description of the fibre content of a diet as it affects rumen function and animal performance. Consequently he proposed both effective NDF (eNDF; ability of a feed to replace a roughage with no negative effect on milk fat content) and physically effective NDF (peNDF; a measure of the physical properties of fibre as it stimulates chewing activity and development of the biphasic stratification of rumen contents) as additional descriptors of the physical characteristics of dietary fibre but to date these concepts have attracted limited attention in the UK. This study examined the effect of replacing increasing amounts of grass silage (GS) on a dry matter (DM) basis in a silage:concentrate ration with pressed sugar beet pulp (PP) on various processes of digestion in the rumen of lactating dairy cows, specifically in relation to chewing activity and rumen mat density.
To measure the effect of stage of maturity of whole-crop (WCW) on its composition, digestibility and feeding value winter wheat was harvested at different maturities in two successive years. In year 1 WCW was harvested at 301(low dry matter (DM)) and 511(high DM) g DM per kg and ensiled and at 584 g DM per kg and treated with 40 kg urea per t DM before being stored (urea-treated WCW). Part of the high DM WCW was treated with an additive containing Lactobacillus buchneri at harvest. In year 2 WCW was harvested at 321 (low DM) and 496 (high DM) g DM per kg and ensiled before both crops were offered to the cows with or without a fibrolytic enzyme sprayed on the forage just before feeding. In both years the WCW was offered ad libitum in a 2: 1 WCW: grass silage DM ratio with 10 kg fresh weight concentrates per day to 40 early-lactation Holstein-Friesian cows in a 13-or 15-week production study with a continuous design and to four fistulated lactating cows in a 4 ✕ 4 Latin-square experiment for measurement of diet digestibility. In both years neutral-detergent fibre (NDF) content decreased and starch content increased with advancing maturity. In the production trials, DM intake increased (P 0·01) with advancing maturity but milk yield was not significantly affected. Milk protein yield was increased by urea-treated WCW. The additives had no effect on food intake or milk production. In year 1, digestibility of all fractions except starch was lower for high DM WCW than low DM WCW but for urea-treated WCW only the digestibility of starch and energy was lower than digestibility of the low DM WCW fractions. The inoculant had no significant effect. In year 2 crop maturity had no significant effect on digestibility but the enzyme reduced the digestibility of neutraland acid-detergent fibre (NDF and ADF, P 0·05). In year 1, each of the forage mixtures was offered to sheep at 12 g DM per kg live weight per day. There were significant treatment effects on the digestibility of DM (P 0·05) and organic matter (OM) (P 0·01) and on DOMD (digestible OM in the DM) (P 0·01) with the highest values being obtained for urea-treated WCW and the lowest for the inoculant-treated high DM WCW. Digestibility coefficients for NDF and ADF were highest for the urea-treated WCW while starch digestibility was essentially complete for all the WCW treatments. The metabolizable energy value (MJ/kg corrected DM) of the WCW decreased with advancing maturity when measured with both the lactating cows (10·4, 9·3 and 9·0) and the sheep (11·4, 10·8 and 10·3) in contrast to the predictions based on the chemical composition (9·6, 10·4 and 12·4). It is concluded that food intake increases with advancing crop maturity but milk production responses are small. Effects on digestibility were inconsistent but the energy value measured in the cows fell with advancing maturity in both years. The increase in crop yield per ha with advancing maturity is likely to be the most important factor influencing the decision to harvest later. The silage additives tested were not beneficial.
Crushed rapeseed and other oil seeds offer an economical source of fat and protein in diets for lactating dairy cows, but the potential inhibitory effects of their unsaturated fatty acids on fibre digestion in the rumen are a concern. Feeding crushed rapeseed in a grass silage-based ration increased milk yield without affecting intake (Reynolds et al., 1998), and had no measurable effects on rumen or total tract digestion (Reynolds et al., 2000). In a companion study, feeding increasing amounts of ground rapeseed in a maize silage-based ration decreased DM intake at higher levels of inclusion (Reynolds et al., 2002). This effect may reflect metabolic effects of rapeseed fatty acid absorption, or negative effects of rapeseed oil on rumen fermentation and fibre digestion. The present study was conducted simultaneously to the production study to determine the incremental effects of ground rapeseed on rumen, post-rumen and total tract digestion in lactating dairy cows fed maize silage-based rations.
Cellulose and hemicellulose are the major structural carbohydrates present in forages and form between 30 and 60% of the forage component of ruminant diets. The complex network of structural carbohydrates and lignin generally leads to low digestibility and limits the efficient utilisation of forages by ruminants. This situation occurs in both developed and developing countries, and in the latter it is particularly pronounced as much of the forage component is based around the use of crop residues (Owen and Jayasuria, 1989). Because forage costs are significantly lower than those of other dietary ingredients, improving forage quality has been a major objective for many research programmes in both the developed and developing world. Improvements in forage quality have been sort through a number of different strategies. These have included conventional breeding techniques, which have included the integration of mutant genes, leading to the development of Brown Midrib varieties of maize and the use of chemical and biological additives. Enzyme supplements are commonly used to improve the nutritive value of feeds for non ruminants and as silage additives where they have been shown to improve silage fermentation, feed intake and performance. Recent work with ruminants has however focused on the use of enzyme supplements to improve feed efficiency by the use of “direct-fed” fibrolytic enzymes. This strategy involves the application of enzymes to feed at or only hours before feeding. These studies have yielded very variable production responses. For any new technology to be implemented widely, the responses achieved must provide an acceptable level of consistency and predictability. The current paper reviews developments in enzymology, production responses achieved and the effects on nutrient digestion.
To examine the effects of manipulating the amount and ruminal degradability of starch on food intake, milk production and digestion in the rumen of lactating dairy cows, cracked wheat (CW) and sodium hydroxide-treated wheat (SW) were compared when offered with either immature (IM) or mature (MM) maize silage given in a 3: 1 dry matter (DM) ratio with grass silage. The total mixed ration (TMR) contained (kg/t DM basis) forage 600, wheat (CW or SW) 170, rapeseed meal 100, soya-bean meal 100, molasses/urea supplement 30 and minerals and vitamins were added at 20 kg/t diet DM. In experiments 1 and 2 respectively, 16 multiparous Holstein-Friesian cows and four similar cows with duodenal and ruminal cannulas were offered four diets (IMCW, IMSW, MMCW, MMSW) in 4 ✕ 4 Latin-square designs. In experiment 3, the in sacco degradability of CW and SW was measured in the rumen of three lactating fistulated cows. In experiment 1 total DM intake was 0·7 kg/day higher and milk yield was 0·5 kg/day higher with MM than IM silage but the increases were not significant and type of wheat had no effect. Milk fat content was reduced by MM silage (P < 0·05) but was unaffected by type of wheat. For milk protein content SW caused a non-significant increase with IM but a decrease (P < 0·05) with MM silage (interaction P < 0·05). There were no significant effects on yield of fat or protein. Neutral-detergent fibre digestibility in the rumen was unaffected by the treatments. Starch intake increased (P < 0·05) with MM silage when compared with IM silage and was accompanied by an increase (P < 0·01) in starch flow to the duodenum and in the amount (P < 0·001) digested in the rumen, although there was no significant change in rumen digestibility. Replacing CW with SW increased starch flow to the duodenum (P < 0·05) and reduced rumen digestibility (P < 0·05). Although the amount of total nitrogen (TN) digested in the rumen and rumen digestibility decreased (P < 0·01) with crop maturity, the flow of TN and non-ammonia nitrogen to the duodenum was unaffected. Total tract digestibility of DM was unaffected by treatments. Although the amount of starch digested in the total tract increased for MM compared with IM silage, reflecting the higher starch intake, total tract starch digestibility was unaffected by treatment and averaged 0·972. There were no main treatment effects on daily mean pH, concentration of ammonia or concentration or molar proportions of volatile fatty acids in the rumen. With SW, effective degradability (outflow rate of 0·08 per h) for both DM and starch was reduced when compared with CW. In conclusion the studies confirm that SW is more slowly fermented than CW and can increase the supply of starch to the duodenum. However the concept that increasing starch supply to the duodenum by a combination of MM silage and SW is likely to be beneficial to milk protein yield or concentration is not established under the present dietary regimen.
This paper reports the results of three experiments designed to attempt to improve the efficiency of milk production from diets based on a 1: 2 dry matter (DM) mixture of grass silage and whole-crop wheat (WCW) harvested at 550 to 600 g DM per kg and treated with 40 g urea per kg DM. In the first experiment a control diet of the forage mixture offered ad libitum with 9 kg fresh weight (FW) per day of a concentrate mix was compared with seven treatments in which the forage or the concentrates were varied. Eight multiparous cows were used in a four-period incomplete change-over design with 4-week periods. Caustic treatment of the WCW increased DM intake (P < 0·001) but tendencies for higher yields of milk and milk protein were not significant. Replacement of 2 kg FW concentrates per day by the same weight of molasses as a 24-h pre-soak of the forage (molasses pre-treatment) or added to the forage at feeding increased DM intake (P < 0·001) but did not increase milk yield or yield of milk solids. Molasses pre-treatment and molasses added to the concentrates reduced milk protein concentration (P < 0·05). Replacement of 2 kg FW concentrates per day by the same weight of ground wheat increased DM intake when added to the concentrates (P < 0·001) but not when added to the forage and milk yield was unaffected by either method of addition. The ground wheat tended to reult in higher milk protein concentrations than the molasses. Increasing the digestible undegradable protein content of the concentrates had no significant effect on food intake or milk production. In the second experiment diet digestibility and energy and nitrogen (N) balance were measured for the control diet and three of the treatments from experiment 1 in four multiparous cows in a 4 ✕ 4 Latin-square experiment with 5-week periods. There were no significant effects on food intake or milk yield. Caustic treatment reduced starch digestibility (P < 0·001) and increased neutral-detergent fibre (NDF) digestibility (P < 0·05) but had no effects on energy utilization. It also reduced N intake (P < 0·01) and urine N losses (P < 0·001) by reducing the ammonia concentration of the WCW. Molasses added to the forage or concentrates reduced milk protein concentration (P < 0·05) and digestibility of both starch and NDF (P < 0·05) but energy utilization was unaffected. In a further Latin-square experiment with the same treatments and four fistulated lactating cows, caustic treatment reduced daily mean ammonia concentration (P < 0·01) and increased daily mean pH (P < 0·01) in the rumen. It is concluded that these treatments did not generally improve the value of WCW although caustic treatment increased milk yield and milk protein yield consistently but not significantly. However practical problems may limit its use on the farm. Urea-treated WCW must be accepted as being a relatively low-energy food although with high intake characteristics, and future work should concentrate on evaluating WCW harvested at an earlier stage of maturity.
Maize distillers grains (MDG) is a high quality by-product feed containing 317 g crude protein (CP)/kg DM and 13.5 MJ metabolisable energy/kg DM, and as such is a valuable traceable feed resource. An earlier study conducted at the Centre for Dairy Research (Sutton et al. 2000) with cows in late lactation using a total mixed ration (TMR) based on maize silage, compared the protein value of MDG with that of soyabean meal (SB). The study showed that MDG could be used to replace SB on a total nitrogen (TN) basis without effecting feed intake or nutrient digestion in the rumen, or flow of non-ammonia nitrogen to the duodenum. The aim of the current study was to determine the effect of replacing SB with MDG on a TN basis, on DM intake and milk production in high yielding lactating dairy cows.
Six multiparous Holstein-Friesian cows were offered a total mixed ration based on maize silage in a repeated measure design to evaluate the partition of gross energy (GE) during early to mid lactation. Four measurements were made at 6-week intervals with energy and nitrogen balances carried out in open-circuit respiration chambers over 6 days during lactation weeks 6, 12, 18 and 24. The intakes of total diet dry matter (DM) corrected for volatile losses (VCDM), organic matter (OM) and GE declined significantly (P < 0•01) as lactation progressed, although apparent digestibility of these fractions was not altered, resulting in a significant (P < 0•01) decline in digestible nutrient intake at each stage of lactation. Methane and urine energy losses were not significantly affected, resulting in significantly (P < 0·001) higher amounts of digestible energy (DE) partitioned to methane and urine as lactation progressed with associated significant reductions in metabolizable energy (ME) intake (MEI) (P < 0·01) and ME as a proportion of DE (P < 0·001) and GE (q) (P < 0·05). With advancing lactation there was a significant (P < 0·001) increase in the amount of ME partitioned to heat (HP/MEI), but no significant change in the amount partitioned to milk and tissue. Individual values for diet metabolizability (ME/GE) at actual (production) levels (qa) (mean 0·625 MJ/MJ) were corrected to an equivalent value at maintenance (qmc) (mean 0·666 MJ/MJ). The overall ME intakes (MJ/day) were: ad libitum, 246, corrected for level of feeding effect, 263, with a predicted ME requirement according to AFRC (1993) (MER93) of 242. Substitution of the calculated qmc into the predictive equations (AFRC, 1993) resulted in a mean maintenance requirement of 57·6 MJ/day (0·464 MJ/kg M0·75/day) whilst the mean value derived from the linear model describing the experimental data was 82·5 MJ/day (0·664 MJ/kg M0·75/day). The mean efficiencies of utilization of ME for milk production derived from AFRC (1993) and the linear regression model were 0·653 MJ/MJ and 0·625 MJ/MJ respectively.
To evaluate the effect of crop maturity on digestion of maize silage in the rumen and post-ruminal digestive tract, four multiparous Holstein-Friesian cows fitted with a simple cannula in the proximal duodenum and a rumen cannula were offered four diets in a 4 ✕ 4 Latin-square design. Forage maize (cv. Hudson) was harvested and ensiled at target dry matter (DM) contents of 230, 280, 330 and 380 g per kg fresh weight (FW) to provide a range of starch contents. The mean values for volatile-corrected DM (VCDM) and starch content of the four maize silages as given were 221, 277, 308 and 372 g/kg FW and 173, 257, 328 and 382 g/kg VCDM respectively. Grass silage (GS) containing 250 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. The diets were 8·7 kg DM per day of a dairy concentrate supplement with one of four forage treatments offered ad libitum. The forage treatments were a 3 : 1 DM ratio of maize silage with GS, designated as T23, T28, T33 and T38. Each period lasted 6 weeks with rumen and duodenal samples being taken over 3 days in week 4 and faeces being collected in respiration chambers over 6 days in either week 5 or 6. Milk yield tended to increase with advancing maturity (30·5, 31·8, 32·5 and 32·3 kg/day) but individual treatment differences were not significant. DM intake increased from 19·62 to 21·30 kg/day (P < 0·05) but there were no significant effects on digestibility in the rumen, post-ruminal tract or total tract. Digestibility of neutral detergent fibre in the rumen declined with increasing starch content in the maize silage (P < 0·05) but total digestibility was not significantly affected. Starch intake increased from 3·11 to 5·04 kg/day (P < 0·001), duodenal flow from 0·40 to 0·89 kg/day (P < 0·01) and the amounts digested in the rumen and post-ruminal tract respectively from 2·72 and 0·34 kg/day to 4·16 and 0·71 kg/ day (P < 0·01). However the only significant effect on starch digestibility was a small fall in total digestibility from a mean of 0·981 for T23, T28 and T33 to 0·966 for T38. There were no treatment effects on nitrogen digestion. The molar proportions of acetic acid and n-caproic acid decreased and that of n-butyric acid increased with advancing maturity. It is concluded that the changes in composition of maize silage with increasing maturity result in large increases in the contribution of starch to DM digested in the rumen but only small differences in rumen fermentation. Post-ruminal starch digestion doubles but this is due to the increased starch concentration of the silage rather than major changes in digestion and the amount is small compared with that likely to result from feeding maize grain.