bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the emetic potential of PDE4 inhibitors in rats
Authors: Robichaud A , Savoie C , Stamatiou P B , Lachance N , Jolicoeur P , Rasori R , Chan C C
Published: June 2006

Type 4 phosphodiesterase (PDE4) inhibitors mimic the pharmacological actions of alpha2‐adrenoceptor antagonists. This has been postulated as the mechanism by which PDE4 inhibitors induce emesis and was also demonstrated by their ability to reverse xylazine/ketamine‐induced anaesthesia. We further characterized this latter effect since it appears to reflect the emetic potential of PDE4 inhibitors.

Selective inhibitors of PDE 1, 2, 3, 4 and 5 were studied in rats, on the duration of anaesthesia induced by the combination of xylazine (10 mg kg−1, i.m.) and ketamine (10 mg kg−1, i.m.) PMNPQ (i.e. 6‐(4‐pyridylmethyl)‐8‐(3‐nitrophenyl)quinoline)  –  PDE4 inhibitor: 0.01 – 3 mg kg−1), like MK‐912 (alpha2‐adrenoceptor antagonist: 0.01 – 3 mg kg−1), dose‐dependently reduced the duration of anaesthesia. In contrast, vinpocetine (PDE1 inhibitor), EHNA (PDE2 inhibitor), milrinone (PDE3 inhibitor) and zaprinast (PDE5 inhibitor) had no significant effect at the doses tested (1 – 10 mg kg−1). Analysis of plasma and cerebrospinal fluid (CSF) of treated animals confirmed the absorption and distribution to the brain of the inactive inhibitors.

Neither MK‐912 (3 mg kg−1) nor PMNPQ (0.1 – 1 mg kg−1) altered the duration of anaesthesia induced via a non‐alpha2‐adrenoceptor pathway (sodium pentobarbitone 50 mg kg−1, i.p.)

Central NK1 receptors are involved in PDE4 inhibitor‐induced emesis. Consistently, [sar9, Met(O2)11]‐substance P (NK1 receptor agonist, 6 μg i.c.v.) reduced the duration of anaesthesia induced by xylazine/ketamine.

In summary, this model is functionally coupled to PDE4, specific to alpha2‐adrenoceptors and relevant to PDE4 inhibitor‐induced emesis. It therefore provides a novel way of evaluating the emetic potential of PDE4 inhibitors in rats.

British Journal of Pharmacology (2002) 135, 113–118; doi:10.1038/sj.bjp.0704457
Cyclic GMP‐dependent vasodilatory properties of LASSBio 294 in rat aorta
Authors: Silva C L M , Noël F , Barreiro E J
Published: June 2006

The effects of LASSBio 294, a new 3,4‐methylenedioxybenzoyl‐2‐thienylhydrazone, on vascular tonus were investigated in isolated rat aortic rings.

LASSBio 294 induced a concentration‐dependent relaxation of intact rat aortic rings with an inhibitory concentration (IC50) of 74 μM (95% confidence limits: 59 – 92). The mechanical removal of the endothelium abolished this effect.

In aortic rings with intact endothelium the effect of 100 μM LASSBio 294 was not altered by the pharmacological inhibition of NOS and cyclo‐oxygenase pathways with 500 μM L‐NAME and 10 μM indomethacin, respectively.

LASSBio 294 (100 μM) was able to relax aortic rings pre‐contracted with high extracellular K+ (KCl 100 mM).

The relaxant effect of LASSBio 294 was fully reversed (and prevented) by the addition of 1 μM ODQ (1H‐(1,2,4)oxadiazolo[4,3‐a]quinoxaline‐1‐one), a selective inhibitor of soluble guanylate cyclase.

LASSBio 294 (100 μM) had no direct effect on PDE3 and PDE4 activities, however, it increased by 150% cyclic GMP content in aortic rings pre‐treated with 100 μM L‐NAME and 10 μM indomethacin, as did 1 μM zaprinast, a selective PDE5 inhibitor.

In conclusion, LASSBio 294 induced relaxation of isolated rat aorta probably by directly increasing cyclic GMP content, possibly as a consequence of PDE5 inhibition.

British Journal of Pharmacology (2002) 135, 293–298; doi:10.1038/sj.bjp.0704473
HIV protease cleaves poly(A)-binding protein
Authors: Álvarez Enrique , Castelló Alfredo , Menéndez-Arias Luis , Carrasco Luis
Published: June 2006

The PABP [poly(A)-binding protein] is able to interact with the 3′ poly(A) tail of eukaryotic mRNA, promoting its translation. Cleavage of PABP by viral proteases encoded by several picornaviruses and caliciviruses plays a role in the abrogation of cellular protein synthesis. We report that infection of MT-2 cells with HIV-1 leads to efficient proteolysis of PABP. Analysis of PABP integrity was carried out in BHK-21 (baby-hamster kidney) and COS-7 cells upon individual expression of the protease from several members of the Retroviridae family, e.g. MoMLV (Moloney murine leukaemia virus), MMTV (mouse mammary tumour virus), HTLV-I (human T-cell leukaemia virus type I), SIV (simian immunodeficiency virus), HIV-1 and HIV-2. Moreover, protease activity against PABP was tested in a HeLa-cell-free system. Only MMTV, HIV-1 and HIV-2 proteases were able to cleave PABP in the absence of other viral proteins. Purified HIV-1 and HIV-2 proteases cleave PABP1 directly at positions 237 and 477, separating the two first RNA-recognition motifs from the C-terminal domain of PABP. An additional cleavage site located at position 410 was detected for HIV-2 protease. These findings indicate that some retroviruses may share with picornaviruses and caliciviruses the capacity to proteolyse PABP.
Influence of milking frequency on the productivity of dairy cows
Authors: Stockdale C. R.
Published: June 2006

Benefits and issues of changing milking frequency from the traditional twice a day are reviewed. Increased efficiency through dairy automation and mechanisation, and the desire to utilise advances in genetic selection, have made milking more frequently than twice a day an attractive option for some farmers. The size of the response to increased milking frequency appeared not to be related to existing milk yield, with the average response to increasing the frequency from 2 to 3 times a day being 3.5–3.8 kg/day. Labour is the single most important cost associated with the decision to increase milking frequency. For this reason, automated milking systems may hold the key to the long-term profitability of challenging cows to produce to their genetic potential. In contrast, reducing milking frequency to once a day has been used to reduce stress on underfed cows or for lifestyle and/or labour considerations. Short-term experiments indicate an average production loss of 21% for once daily relative to twice daily milking. Full lactation experiments suggest greater losses of 35–50%, but there is evidence that cows can adapt to longer milking intervals and this, coupled with increased stocking rate and care to maximise milk removal, may restrict yield losses to less than 10% on a whole-farm basis.
Mode of action of back-line application of spinosad, a non-systemic parasiticide, on sheep
Authors: Lowe L. B. , Hacket K. C. , Rothwell J. T. , Nicholls P.
Published: June 2006

Spinosad, applied as a jetting solution or dip is an efficacious, non-systemic treatment for the control of Bovicola ovis in sheep. This paper describes the effect of back-line treatment width and group housing of animals on the efficacy of spinosad for the control of lice. A 0.4 mg/kg liveweight dose was found to be the suboptimal dose of spinosad for the control of body lice in a dose titration study and was used to investigate application and housing effects in a second study. Lousy Merino sheep were treated with either a narrow 3-cm application of spinosad or with a wider 25-cm swathe. After treatment they were either kept alone or in groups of 6 sheep per pen. Lice were counted at day 0 and every 14 days to 70 days after treatment before estimation of the percentage of lice control and analysis of treatment effects. A much higher percentage of lice control was achieved with 0.4 mg/kg in the second study than in the first, possibly because of differences in formulation used. The wider application width gave significantly higher (P<0.05) control of lice than the narrow application when sheep were either housed alone or in groups up to day 42 post-treatment. Greater control of lice was seen in group-housed sheep compared with sheep housed individually (P<0.05) up to day 70. Using broader application widths combined with holding the animals together after treatment with pour-on formulations may optimise the delivery and efficacy of ectoparasiticides for livestock.
Colostrum quality of ewes of calm temperament is not responsible for low lamb mortality
Authors: Hart K. W. , Chadwick A. , Sebe F. , Poindron P. , Nowak R. , Blache D.
Published: June 2006

Perinatal lamb mortality is a serious issue for the sheep industries. Starvation is implicated in many of these lamb deaths. Ewes with a calm temperament lose significantly fewer lambs than ewes with nervous temperament, particularly in the critical first 3 days after birth. Colostrum provides essential nutrition to neonatal lambs. This research set out to determine whether ewe temperament affects the quantity and quality of colostrum that ewes produce. Calm temperament was found to have an influence on the viscosity of colostrum 6 h after birth. High variability in all aspects of colostrum production were found in the study and may be a limiting factor in lamb survival in certain circumstances. There is little evidence, however, to suggest a strong association with ewe temperament and is therefore unlikely to explain the lower lamb mortality that is reported to occur among calm ewes.
Genetic resources to increase the profitability of crossbred lamb production
Authors: Fogarty N. M. , Ingham V. M. , McLeod L. , Gaunt G. M. , Cummins L. J.
Published: June 2006

The gross margin returns of first cross ewes by different sires have been evaluated on an equivalent carrying capacity basis by taking account of the feed requirements for the ewes and lambs and their varying performance and requirements throughout the annual production cycle. The study involved 2846 crossbred ewe progeny generated by 91 maternal sires from several breeds at 3 sites over 3 years including genetic links. The ewes were joined to terminal sire rams for 3 years and 8878 of their second cross lamb carcasses were included in the evaluation. The annual gross margin (A$GM) for individual ewes included income from lamb carcasses (with fat and weight discounts), lamb skins and ewe wool production, and costs for management and marketing. Individual feed requirements were calculated for ewe maintenance, gestation, lactation and lamb growth (pre- and post-weaning) and $GM was expressed on a dry sheep equivalent (dse) basis. Sire breed was not significant with a range of $5.28 GM/dse between sire breed means. There was a considerably greater range of up to $15 GM/dse among most of the sire ewe progeny groups within breeds and overlap among all sire breeds. Lamb turnoff rate was the major profit driver with lamb growth rate and carcass fat levels also contributing. The opportunities for genetic improvement in profitability of lamb enterprises are discussed.
Quantifying the rate of pH and temperature decline in lamb carcasses using medium voltage electrical stimulation in an Australian abattoir
Authors: Pearce K. L. , Hopkins D. L. , Toohey E. , Pethick D. W. , Richards I.
Published: June 2006

The current study evaluated the effectiveness of a medium voltage post-dressing electrical stimulation unit at different current and pulse width settings on pH decline. The objective was to optimise these settings to ensure that a high proportion of carcasses would reach pH 6.0 when the carcass was between 18–25°C according to the guidelines set by the Australian Sheep Meat Eating Quality (SMEQ) program. In the first experiment, 3 different current (400, 700 and 1000 mA) and pulse width (1, 2.5 and 5 ms) settings plus a control (0 mA and 0 ms) were applied to carcasses for 34 s at a frequency of 15 Hz with 7 sheep per treatment over 3 consignments (n = 210 carcasses). The pH–temperature decline was evaluated for all carcasses. Based on the SMEQ guidelines, 43% of stimulated carcasses reached a pH of 6.0 between a carcass temperature of 18–25°C, compared with 14% of unstimulated controls. Furthermore, 21% of carcasses reached a pH of 6.0 before the carcass temperature reached 25°C and 36% did not reach a pH of 6.0 by the time the carcass was 18°C. Alternatively, under the Meat Standards Australia (MSA) pH–temperature guidelines, carcasses should reach pH 6.0 between 12 and 35°C; 87% of stimulated carcasses reached a pH of 6.0 between 12–35°C, compared with 39% of unstimulated controls. One percent of carcasses reached a pH of 6.0 before the carcass temperature reached 35°C and 12% did not reach a pH of 6.0 by a carcass temperature by the time the carcass was 12°C. The abattoir in this study had a very fast chilling regime which resulted in carcasses reaching pH 6.0 at low temperatures and accounted for the low number of carcasses reaching a pH of 6.0 between 18–25°C. There was no effect of different current and pulse widths on the rate of decline, temperature at pH 6.0 or initial pH, which was attributed to the late application of electrical stimulation postmortem when muscle contraction is dependant on direct muscle stimulation. The combination of 2.5 ms and 1000 mA was the best performing treatment with respect to both SMEQ and MSA guidelines and the number of carcasses reaching the pH–temperature window. This treatment had the highest percentage of carcasses reaching the SMEQ window (60%) and MSA window (97%). Furthermore, it resulted in the lowest number of carcasses not reaching pH 6.0 by a carcass temperature of either 12 or 18°C, making it the most suitable to an abattoir with a fast chilling regime. Modulation and frequency manipulation of the segmented electrodes were assessed with the frequency manipulation resulting in the greatest stimulation response. Further work is needed to understand the effect of manipulating the frequency on the system overall or of the individual modules as well as changing the stimulation time.
Rate of feed degradation in strip-grazing dairy cows
Authors: Williams Y. J. , Doyle P. T. , Egan A. R.
Published: June 2006

Nylon bags containing Persian clover, perennial ryegrass or perennial pasture hay were incubated for 12-h periods in lactating dairy cows grazing Persian clover pasture. The hypothesis was that the rate of dry matter disappearance over the first 12 h of incubation in the rumen would be lower when bags were inserted at a time when the rumen pH was at its lowest point for the day compared with a time when it was at its highest. It was also hypothesised that the reduction in rate of DM loss over 12 h at the initially low and then fluctuating rumen pH would be lower for Persian clover than for perennial ryegrass and the hay. Rumen fistulated cows grazing at 4 different pasture allowances (9, 16, 32 and 53 kg DM/day; 4 cows per treatment) were used in a completely randomised, split-plot design. The nylon bag incubation periods were 0700 to 1900 hours (period 1) and 1900 to 0700 hours (period 2) and rumen fluid pH was measured every 3 h during these periods. The ruminal fluid pH at the time of insertion of the nylon bags was higher (6.3 v. 5.7; P<0.001) in incubation period 1 than in period 2, and there was an interaction between the effects of incubation period and pasture allowance on the average rumen fluid pH in each period. Rate of DM loss was higher (3.47 v. 3.28%/h; P = 0.019) in incubation period 1 than in incubation period 2, highest (P<0.001) for clover, followed by ryegrass and then hay (5.05 v. 3.15 v. 1.93%/h) and higher (P<0.001) in cows grazing at the low (9 and 16 kg DM/cow) compared with high (32 and 53 kg DM/cow) allowances. There was a significant linear relationship (P<0.05) between DM loss rate calculated over 12 h and rumen fluid pH for grass and hay, but for clover this relationship only occurred in incubation period 2. These results suggest that more than 1 factor is important for determining feed degradation rates in the rumen at any particular time and that only using rates of forage DM loss that are obtained from nylon bags inserted prior to the morning feed, may overestimate the extent of rumen degradation of the feed eaten over the whole day in cows strip-grazing highly digestible pastures.
Effects of treadmill inclination and speed on forelimb muscle activity and kinematics in the horse
Authors: Hodson-Tole Emma
Published: June 2006

The study aimed to investigate the effect of speed and incline on EMG activity in thebrachiocephalicusmuscle and the long and lateral heads of thetriceps brachiimuscle. Six horses were exercised on a treadmill at walk (1.7 m s-1), trot (4.0 m s-1) and right lead canter (7.2 m s-1) on a 0 and 8% incline. Kinematics (120 Hz) and electromyography (EMG) (2000 Hz) data were collected simultaneously from the left forelimb of each horse. Significant differences in relation to velocity and incline were identified using two-way ANOVA andpost hocStudent–Newman–Keuls tests (P≪0.05). The degree of association between timing of peak EMG intensity and the timing of maximum protraction/retraction angles was assessed using ANCOVA. Increases in velocity led to an increase in stride length and reduction in stride duration. Exercise on the incline increased stance duration and decreased swing duration, while limb protraction/retraction increased. The time of peak EMG activity in thebrachiocephalicuswas highly related to time of maximum limb retraction (r2=0.84). The time of peak EMG activity in the long head of thetriceps brachiiwas highly associated with time of maximum limb protraction (r2=0.87). Increases in velocity and incline both caused an increase in the intensity of the EMG signal from each muscle. Duration of EMG activity was prolonged in the long head of thetriceps brachiimuscle and in thebrachiocephalicusmuscle as velocity increased. Treadmill speed and slope therefore both alter the workload placed on forelimb muscles.
Incidence of Pediatric and Neonatal Intensive Care Unit–Acquired Infections
Authors: Banerjee Shailendra N. , Grohskopf Lisa A. , Sinkowitz-Cochran Ronda L. , Jarvis William R. ,   National Nosocomial Infections Surveillance System; the Pediatric Prevention Network
Published: June 2006

Objective.

To compare the cumulative incidence of infections acquired in the pediatric intensive care unit (PICU) and neonatal intensive care unit (NICU).

Design.

Estimation of the cumulative incidence of infections with data obtained from the Pediatric Prevention Network (PPN) point-prevalence survey and observed rates from the National Nosocomial Infections Surveillance (NNIS) system.

Setting.

Ten hospitals participated in both the PPN survey and NNIS system.

Participants.

All patients present on the PPN survey dates (August 4, 1999, or February 1, 2000) in the NICUs or PICUs of the PPN hospitals were included in the survey. Point prevalences for PICU-acquired and for NICU-acquired infections at these hospitals were calculated from the survey data. The cumulative incidence rates were estimated from the point prevalence rates using a standard formula and a standard method for calculating the time to recovery (ie, on the basis of the assumption that discontinuance of antimicrobial therapy indicates recovery from infection); alternate methods to judge the time to recovery from infection were also explored.

Results.

The average cumulative incidence of intensive care unit-acquired infection for NICUs and PICUs combined (all units), as measured by NNIS, was 14.1 cases per 100 patients; in comparison, the prevalence was 14.06 cases for 100 patients (median difference, —0.95 cases per 100 patients; 95% confidence interval, —4.6 to 5.0 cases per 100 patients), and the estimated cumulative incidence using the standard method of calculating the time to recovery was 13.8 cases per 100 patients (median difference, —1.5 cases per 100 patients; 95% confidence interval, —9.1 to 2.9 cases per 100 patients). Estimates of cumulative incidence using alternate methods for calculation of time to recovery did not perform as well (range, 4.9-100.9 cases per 100 patients). The average incidence density for all units, as measured by the NNIS system, was 6.8 cases per 1,000 patient-days, and the estimate of incidence density using the standard method of calculating the time to recovery was 3.6 cases per 1,000 patient-days (median difference, 4.3 cases per 1,000 patient-days; 95% confidence interval, 0.9 to 9.2 cases per 1,000 patient-days). Estimated incidence densities using alternate methods for determining recovery time correlated closely with observed incidence densities.

Conclusions.

In this patient population, the simple point prevalence provided the best estimate of cumulative incidence, followed by use of a standard formula and a standard method of calculating the time to recovery. Estimation of incidence density using alternate methods performed well. The standard formula and method may provide an even better estimate of cumulative incidence than does simple prevalence in general populations.
Molecular Characterization of Methicillin-ResistantStaphylococcus aureusSpread by Neonates Transferred From Primary Obstetrics Clinics to a Tertiary Care Hospital in Korea
Authors: Ko Kwan Soo , Park Sulhee , Peck Kyong Ran , Shin Eun Jung , Oh Won Sup , Lee Nam Yong , Song Jae-Hoon
Published: June 2006

Objective.

To investigate the characteristics and origins of methicillin-resistantStaphylococcus aureus(MRSA) strains isolated from neonatal patients admitted to a tertiary care hospital from local and primary care obstetrics clinics.

Design.

Molecular typing study.

Setting.

A 1,278-bed tertiary care hospital (Samsung Medical Center) and 2 primary obstetrics clinics in Seoul, Korea.

Patients.

The genotypic characteristics of 12 MRSA samples isolated from 11 neonatal patients transferred from 2 primary care obstetrics clinics to a tertiary care hospital were investigated by means of multilocus sequence typing,spa(staphylococcal protein A) typing, andSCCmectyping. Ten MRSA strains isolated from workers and environments in the associated obstetrics clinics were also investigated.

Results.

Although the antibiograms of isolates from 2 obstetrics clinics differed, no strain showed multidrug resistance to antimicrobials. Multilocus sequence typing analysis showed that all 22 MRSA isolates analyzed in this study had sequence type 1 (with the allelic profile 1-1-1-1-1-1-1), sequence type 493 (62-1-1-1-1-1-1), or a novel sequence type (25-1-1-1-1-1-1) and that all belonged to a single clonal complex (clonal complex 1). Moreover, they all containedSCCmectype IVA and the identicalspatype (UJEBKBP). These genotypic characteristics are similar to those of typical community-associated MRSA strains rather than the hospital-acquired MRSA strains common in Korea.

Conclusion.

The findings of this study suggest that community-acquired MRSA strains can spread in primary care clinics and be imported into tertiary care settings.
Effects of human immunodeficiency virus type 1 transframe protein p6* mutations on viral protease-mediated Gag processing
Authors: Chiu Hsu-Chen , Wang Fu-Der , Chen Yi-Ming Arthur , Wang Chin-Tien
Published: June 2006

The proteolytic processing of human immunodeficiency virus (HIV) particles mediated by the viral pol-encoded protease (PR) is essential for viral infectivity. The pol coding sequence partially overlaps with the gag coding sequence and is translated as a Gag–Pol polyprotein precursor. Within Gag–Pol, the C-terminal p6
gag
domain is replaced by a transframe peptide referred to as p6*, which separates the Gag nucleocapsid domain from PR. Several previous in vitro studies have ascribed a PR-suppression regulatory function to p6*. Here, it was demonstrated that an HIV-1 Gag–Pol lacking p6* is efficiently incorporated into virions when coexpressed with HIV-1 Gag precursor. However, the released virions are not processed appropriately and show a greatly reduced viral infectivity. This suggests that the p6* is indispensable during the process of PR-mediated virus particle maturation.
Description of a new Lake Tanganyikan cichlid fish of the genus Cyprichromis(Perciformes: Cichlidae) with a note on sexual dimorphism
Authors: Takahashi T. , Hori M.
Published: June 2006

Cyprichromis coloratus, a new cichlid species, is described based on 41 type specimens from the Zambian coast of Lake Tanganyika. It differs from Cyprichromis microlepidotus by having fewer scales in the longitudinal line (41–44 v. 59–70 in C. microlepidotus) and upper lateral line (31–36 v. 47–59), from Cyprichromis leptosoma by more dorsal‐fin spines (14–15 v. 11–13 in C. leptosoma) and longitudinal line scales (41–44 v. 38–40), from Cyprichromis pavo by fewer dorsal‐fin spines and soft rays (29–31, usually 30, in total v. 30–32, usually 31, in C. pavo), and from Cyprichromis zonatus by shallower body depth [24·0–28·5 (26·4 ± 1·1)% of standard length v. 24·5–30·5 (28·4 ± 1·3)% in C. zonatus] and smaller eye [eye length 25·2–30·9 (27·2 ± 1·1)% of head length v. 27·9–33·3 (30·2 ± 1·2)%]. The new species is also separable from C. microlepidotus, C. pavo and C. zonatus by absence of distinct small spots on the body (v. pearl grey and yellowish small spots along scale rows on body at least in males of C. microlepidotus and C. pavo), its distinct dichromatism (particularly on the caudal fin) between males of the same population (v. dichromatism absent in C. zonatus) and absence of vertical bands (v. three or four distinct vertical bands beneath dorsal fin base in live males of C. zonatus). Cyprichromis coloratus n. sp. also exhibits sexual dimorphism, females having a larger head and males having longer pelvic fin, differences which are discussed in relation to reproductive behaviour. A key to the five species of Cyprichromis is included. A lectotype is designated for Cyprichromis leptosoma.
Taxonomy and molecular phylogeny of Lethenteron lampreys in eastern Eurasia
Authors: Yamazaki Y. , Yokoyama R. , Nishida M. , Goto A.
Published: June 2006

Allozyme analyses of lampreys (genus Lethenteron) in eastern Eurasia showed that samples of L. reissneri from the upper Amur River, Russia, possessed the diagnostic alleles of L. kessleri(MDH‐3*‐93). These samples were closely related to L. kessleri samples in the Ob, Lena and middle Amur Rivers and on Sakhalin and Hokkaido Islands. On the other hand, they were distantly related to samples of the northern and southern forms of L. reissneri in the Japanese Archipelago and the southern Korean Peninsula. The number of trunk myomeres in L. reissneri from the upper Amur (63–76) strongly overlapped the number in L. kessleri(64–73), but were markedly displaced from those of the northern (51–66) and southern forms (49–62). These results suggest that L. reissneri in the upper Amur basin is likely to be the same taxonomic entity as L. kessleri reported from eastern Eurasia. The genetic and morphological divergences from L. reissneri in the type locality make it appropriate to regard the northern and southern forms as distinct species, L. sp. N and sp. S. Despite the close relationships found among L. japonicum, the L. reissneri complex and L. sp. N, L. sp. S was highly divergent from other species of Lethenteron, Lampetra and Entosphenus. In the monophyletic group comprising L. japonicum, the L. reissneri complex and L. sp. N, the direction of life‐history evolution presumed from the most parsimonious character reconstruction on the molecular tree was inconsistent with the previous hypothesis that nonparasitic species arise from parasitic species, indicating the necessity of detailed assessment of characteristics. On the other hand, L. sp. S may be a relict species of the coancestor of Lethenteron, Lampetra and Entosphenus.
Ontogenetic diet shifts and diet overlap among three closely related neotropical armoured catfishes
Authors: Mol J. H.
Published: June 2006

Analysis of stomach contents of larvae, juveniles and adults of three closely related armoured catfishes in coastal plain swamps of Suriname, South America, revealed major ontogenetic diet shifts. Larvae of Hoplosternum littorale, H. thoracatum and Callichthys callichthys showed a restricted diet of rotifers and microcrustacea. Diets of juveniles and adults were more diverse, but large volumes of microcrustacea, aquatic insect larvae and detritus were always present. In all three species diet overlap was especially low between larvae and adults. The proportion of detritus in the stomach was positively related to fish size, which probably reflected the inability of larger size classes to separate effectively benthic invertebrate prey from bottom substrata, and not a specialization towards detritivory. Adults showed only minor seasonality in diet composition, and no effect of season on diet breadth. Interspecific diet overlap among larvae, juveniles and adults did not differ significantly from 1 (complete overlap). Lack of food partitioning was probably related to a similar morphology of the three catfishes. Intraspecific between‐size class diet overlap was considerably lower than interspecific within‐size class overlap. It is suggested that large interspecific diet overlap occurred because food was not limiting the populations of these catfish. However, the nest habitats of the three species differed.
The effect of the rate of temperature increase on the critical thermal maximum for parr of Atlantic salmon and brown trout
Authors: Elliott J. M. , Elliott J. A.
Published: June 2006

The critical thermal maximum for salmon and trout parr was not affected significantly by age or acclimation temperature, and increased asymptotically with the rate of temperature increase. Mean thermal maxima were estimated with poor precision at high and low rates of temperature increase, and high precision at rates of 1 and 2°Ch−1.
Fecundity and its variability in orange roughy: effects of population density, condition, egg size, and senescence
Authors: Koslow J. A. , Bell J. , Virtue P. , Smith D. C.
Published: June 2006

Fecundity of orange roughy in 1987–1989 adjusted for standard length (S.L.) varied significantly between New South Wales (42 787 eggs female−1) South Australia (35 339 eggs female−1) and east Tasmania (31 085 eggs female−1). Only 10‐17% of the variability in fecundity of eastern Tasmania orange roughy was explained by s.l. in any year from 1987–1992. However, liver condition and age of the fish, in combination with s.l., explained 27% of the variation in fecundity. Fecundity declined in fish over 60 years old. It was also significantly correlated with lipid levels in the ovary, in particular, with triacylglycerol as a proportion of the total lipid fraction. Significant interannual changes in fecundity appeared to be related to the impact of fishing. From 1987–1992, the orange roughy stock off east Tasmania was reduced by 50% by the fishery, and mean fecundity increased 20% over that period. This compensatory increase in individual fecundity, combined with an apparent increase in the proportion of females spawning annually from 54 to 71%, limited the decline in the population's egg production over this period to approximately 15%.
Ontogeny of haemoglobin polymorphism in cod
Authors: Fyhn U. E. H. , Johansen T. , Nævdal G. , Thorkildsen S.
Published: June 2006

Haemoglobins of 0‐group cod from 30 to 150 mm length were analysed by agar gel electrophoresis and isoelectric focusing to identify the lower size limit for determination of the haemoglobin polymorphisms in cod; both the main system which has been known for more than 30 years and the recently described subgroups. The juvenile fish studied had higher concentration of the HbII‐component (split into three bands at these fish sizes) compared to older fish. The main haemoglobin types could be distinguished clearly and reliably at a fish size of about 35 mm and above. The subgroups of the HbI‐components, however, could not be identified reliably until the cod were about 80 mm.
Thermal Shock Testing
Authors: BUESSEM W. R.
Published: June 2006

Practical experience has shown that thermal shock tests do not lead to generally useful test data. This is probably due to the fact that thermal shock failure is a complicated function of the external thermal shock conditions and of the temperature functions of five different material properties. These five material functions appear in a different combination in almost every thermal shock case and cannot be extracted from thermal shock test data. It is recommended that these five properties and their temperature dependence be determined by separate standard tests, not employing thermal shock. If the five property functions are known, thermal shock tests proper can be used to determine the maximum thermal shock stresses in any device.
Effect of Porosity on Thermal Stress Fracture
Authors: COBLE R. L. , KINGERY W. D.
Published: June 2006

Sintered alumina with from 4 to 50% porosity was prepared by incorporating crushed naphthalene in a casting slip. Thermal stress resistance was determined from the radial temperature difference required to fracture hollow cylinders under steady‐state conditions. Thermal stress resistance decreases with increasing porosity; resistance to thermal stresses at 50% porosity is about one‐third of that estimated for zero porosity.

Summary and Conclusions

Samples with controlled porosity were prepared by incorporating naphthalene flakes in an alumina casting slip. Samples were prepared and fired under identical conditions so that the continuous solid phase was identical for all samples. Steady‐state thermal stress tests described lead to the following conclusions:

(1) Resistance to thermal stress, R (maximum steady‐state Δt for fracture), decreases with increasing porosity. The resistance for a sample with 50% porosity is about one‐third that for dense samples.

(2) Resistance to thermal stress determined by the maximum heat flow permissible, R', decreases more rapidly than R because increasing porosity lowers the thermal conductivity. This factor for a sample with 50% porosity is about one‐sixth the value for dense samples. This is the factor generally applicable to thermal shock conditions.

(3) Resistance to thermal fracture with a constant rate of surface temperature rise is directly proportional to R, since thermal diffusivity is unaffected by porosity.
Magnetic Ceramics: VI, Evaluation of Some Methods of Nickel Ferrite Formation
Authors: ECONOMOS GEORGE
Published: June 2006

The extent of nickel ferrite formation, as affected by four preparatory techniques, was investigated by determining the magnetic moment of the reacted powder with a vibrating‐coil magnetometer. The oxide, carbonate, hydroxide, and oxalate methods were used. At low temperatures the hydroxide and oxalate techniques were found to give the greatest yield of ferrospinel. The hydroxide method yielded a magnetic material by precipitation. Weight‐loss measurements were correlated to the magnetic data.
Effects of Oxygen Partial Pressure on the Oxidation of Silicon Carbide
Authors: JORGENSEN PAUL J. , WADSWORTH MILTON E. , CUTLER IVAN B.
Published: June 2006

The rate of oxidation of silicon carbide was studied at different partial pressures of oxygen. The diffusion rate constant was found to vary with the logarithm of the partial pressure of oxygen according to the theory of oxidation of thin films as proposed by Engell and Hauffe. An alternative explanation based on the change of free energy with surface coverage was also found to fit the data.
Moisture Movement and Readsorption Phenomena in Dried Clay Articles
Authors: HOPE I. C. , GABRIEL J. , McDOWALL I. C.
Published: June 2006

Readsorption of moisture occurs when dried ceramic articles are exposed to an atmosphere bearing water vapor with a partial pressure greater than that of the moisture remaining in the specimens. This readsorption is accompanied by a variable amount of expansion. It is suggested that stresses arising from differential expansion between the moist outside and the drier core are the cause of readsorption cracking or permanent loss of strength. Evidence is presented that diffusion of water vapor through a clay mass does not follow Fick's law, and the effect of this behavior on moisture and stress gradients within the piece is discussed. Calculations of the surface area from readsorption data yield values similar to those obtained by conventional methods despite simplified calculations based on Fick's law. A method of determining the tensile strength which is believed not to have been previously used for clay testing is described.
Solid‐Solid and Solid‐Vapor Reactions and a New Phase in the System Mn‐O
Authors: KLINGSBERG CYRUS , ROY RUSTUM
Published: June 2006

The univariant equilibrium pressure‐temperature curve along which β‐MnO2, Mn2O3, and O2 are stable together has been determined up to a Po2 of 200 atmospheres with a trace of water as a catalyst. The analogous curve for the assemblage Mn2O3, Mn3O4, and O2 has also been determined. In both cases the experimental data differ considerably from the thermodynamic calculations. Interconversion studies of the γ, ρ, ɛ and ramsdellite phases indicate only that γ‐MnO, is probably not a poorly crystallized ramsdellite. A new phase probably containing mainly trivalent manganese has been obtained under a wide variety of conditions. The absence of any consistent X‐ray diffraction line shifts in either the MnO or Mn3O4 phases when they were prepared with different stoichiometries raises some question regarding the extent of stable solid solution in these two phases in the system Mn‐O.
Formation of Zircon from Zirconium Dioxide and Silicon Dioxide in the Presence of Vanadium Pentoxide
Authors: MATKOVICH V. I. , CORBETT P. M.
Published: June 2006

The high‐temperature formation of zircon from zirconium dioxide and silicon dioxide in the presence of vanadium pentoxide was studied. A reaction between zirconium dioxide and vanadium pentoxide appeared to take place at about 730°C. That reaction product then reacted with silicon dioxide to form zircon. The experiments suggest that such zircon contains a few per cent of tetravalent vanadium in solid solution and has a light blue color. It appeared that the end product under equilibrium conditions would be pure zirconium silicate since vanadium pentoxide or tetroxide was liberated under prolonged heating. Zircon also formed from silicon dioxide and zirconium dioxide in the presence of niobium or tantalum pentoxide.
Phase Equilibria in the System MgO—FeO—Fe2O2, in Temperature Range 1400° to 1800°C
Authors: PHILLIPS BERT , MUAN ARNULF
Published: June 2006

Equilibrium relations in isothermal sections through the system MgO‐FeO‐Fe2O3 have been determined in the temperature range 1400° to 1800°C. Oxide mixtures prepared from reagent‐grade chemicals were equilibrated and subsequently quenched to room temperature while sealed in 80Pt20Rh tubes. The data obtained for the isothermal sections are used to infer equilibrium relations existing along the liquidus surface of the system.
Thermal Conductivity and Expansion of BeryIIia at High Temperatures
Authors: TAYLOR R. E.
Published: June 2006

The thermal conductivities of several specimens of BeO were measured from 350° to 2000°C and were found to follow exactly the 1/T relation to 1700°C, where several competing phenomena occurred. One of these phenomena was associated with grain growth. Another questioned the validity of the 1/T law at temperatures where the mean free path approached interatomic distances. Thermal expansions of hot‐pressed and isostatically pressed BeO varying from 50 to 99%, density were measured from 20° to 2200°C. Decrepitation occurred at 207O°C.
Moisture‐Expansion Characteristics of a Fired Kaolinite‐Hydrous Mica‐Quartz Clay
Authors: COLE W. F.
Published: June 2006

The natural and autoclave moisture expansions of a fired clay containing kaolinite, hydrous mica, and quartz were studied. A relation was established between the two expansions, which, together with a moisture‐expansion peak at about 1000°C, is explained in terms of the poorly crystalline and noncrystalline phases developed during firing. When low‐fired specimens that were exposed to moisture were desorbed by re‐firing, the shrinkage that accompanied the loss of moisture was interrupted by an expansion at about 5OOOC. This expansion depended on the firing temperature and probably was caused by the dehydroxylation of hydrous mica regenerated from mica anhydride by moisture sorbed after firing. In the case of specimens fired above the moisture‐expansion peak, the moisture responsible for expansion must be held in much the same way in the natural and in the autoclaved specimens. A study of the kinetics of moisture expansion showed a linear relation between the magnitude of expansion and the log of time for the period during which the specimens were exposed to moisture in the air. A similar relation existed for specimens fired from 1000° to 1150°C and autoclaved from 2 to 200 hours. It is further shown that it was possible, using preexisting data, to estimate, from the magnitude of expansion after a short period, the expansion to be expected at any time within the period to which the preexisting data referred.
Preparation of Oxide Glass Films by Reactive Sputtering
Authors: ROBERT SINCLAIR W. , PETERS F. G.
Published: June 2006

A method of depositing oxide glass films on a substrate is presented. The method involves the sputtering of a metal or semiconductor electrode in an oxidizing atmosphere (so‐called reactive sputtering). The films obtained are of good quality, unstrained, and adhere well to the substrate. Films of considerable thickness can be deposited and the substrate need not be heated during the process. The preparation of lead tellurite glass films, silica and germania glass films, silicate glass films, and stannate glass films is described. Some data on the kinetics of film growth and on the physical properties of these materials are presented.
Chemical Durability of Arsenic‐Sulfur‐Iodine Glasses
Authors: LIN F. C. , HO S.‐M.
Published: June 2006

Arsenic‐sulfur‐iodine glasses, recently described by Flaschen et al., were prepared and exposed to various neutral, acidic, and alkaline solutions. Chemical durability, reported in terms of weight loss per unit of surface exposed, was correlated with glass composition, test temperature, exposure duration, and solution pH. Physical properties, such as density, melting temperature, deformation temperature, linear thermal expansion coefficient, and relative fluidity at melting and room temperatures, are also reported. These low‐melting inorganic glasses were found to exhibit excellent resistance to moisture and to acids, including hydrofluoric acid. On the basis of interpretation of the test data, the structure appeared to be a random arrangement of long‐chain sulfur and branched‐chain arsenic‐sulfur polymers.
A Strength–Porosity Relation Involving Different Pore Geometry and Orientation
Authors: BROWN S. D. , BIDDULPH R. B. , WILCOX P. D.
Published: June 2006

A number of empirical and semiempirical expressions which relate the strength of brittle polycrystalline materials to the total porosity have been proposed by various investigators. The present study demonstrates from a purely theoretical point of view that not only the total porosity but the pore shape and orientation are important factors affecting the strength. A strength‐porosity relation is derived that takes pore shape and orientation into account. Examples of how various types of pores should affect the strength are presented.
Studies in Germanium Oxide Systems: I, Phase Equilibria in the System Li2O—GeO2
Authors: MURTHY M. KRISHNA , IP J.
Published: June 2006

Phase equilibrium relations in the system Li2O‐GeO2 were determined using standard quenching techniques. In contrast to published literature five congruently melting compounds were found to exist. They are Li2O·7GeO2, 3Li2O O·8GeO2, Li2O O·GeO2, 3Li2O O·2GeO2, and 2Li2O.‐GeO2. The melting points, respectively, are 1033°± 5°C, 953°± 5°C, 1245°± 15°C, 1125°± 15°C, and 1280°± 15°C. Simple binary eutectic relations exist among the compounds. The eutectic temperature between 1:7 and GeO2 is 1025°± 1h0°C at about 96.8 wt% GeO2; the eutectic temperature between the 1:7 and 3:8 compounds is 935°± 10°C at about 90.9 wt% GeO2; the eutectic temperature between the 3:8 and 1:1 compounds is 930°± 10 °C at about 89.8 wt% GeO2. Liquidus data for compositions richer in lithia than the 1:1 compound are only approximate because of the difficulty of quenching them; the phase relations between the 1:1 and 3:2 and between the 3:2 and 2:l compounds, however, are found to be of the simple binary eutectic type. The glass–forming region was also determined. Melts allowed to cool in air crystallized. When, however, the melts were quenched, glasses containing as much as 8 wt% GeO2 could be prepared in 5–g quantities. Both the refractive index–composition and density–composition curves for the glasses showed maxi–mums at about 6 to 8 wt% Li2O.
Bubble‐Induced Nucleation and Crystal Growth in Glass
Authors: KLINGSBERG CYRUS
Published: June 2006

Evidence that bubbles can cause annular nucleation and subsequent crystal growth on the surface of Bao‐Al2O3‐TiO2‐SiO2, glasses is presented. The crystalline rings were identified as hexacelsian, BaAl2Si2O8 (the hexagonal or high‐temperature polymorph of celsian). Size, character, and suggestions as to the genesis of these rings are given.
Structure and Mechanism of Conduction of Semiconductor Glasses
Authors: JANAKIRAMA‐RAO BH. V.
Published: June 2006

The area of glass formation in the system GeO2‐P4O10‐V2O5 and the properties of the glasses in this area were determined. The glasses displayed electronic conduction at room temperature (25°C). Resistivity ranged from 500 ohm‐cm to 109 ohm‐cm at 25°C. Some of the glasses had unusual negative temperature coefficients of resistance of the order of ‐760,000 ppm °C−1 in the range 25° to ‐55°C. Volt‐ampere characteristics indicated nonlinearity suitable for thermistor application. Other unusual properties included high refractive indices from 1.6 to >2.0 and dielectric constants from 6 to 33 at 1 Mc and 25°C. Values of loss‐tangents, however, were high. Infrared spectra indicated that the V5+ ion existed in sixfold coordination in the glassy state as well as in the devitrified crystalline state. The normal vibrational frequency of the V–O bond at 1015 cm−1 was observed for all glasses in the system. Property versus composition curves indicated that density, refractive index, and dielectric constant of ternary glasses in the system do not obey the additivity rule. The density versus mole % V2O5 curve goes through a minimum. Derived quantities from experimental data indicate pronounced influence of V2O5 on oxygen packing in the system. Addition of SiO2, even in small quantities, destroys glass formation. The structure of these glasses, which differs from that of silicate glasses, is discussed. A mechanism of conduction is suggested, based on evidence from magnetic susceptibility, chemical analysis, activation energy, and infrared spectra.
Phase Equilibria in the System CaO‐MgO‐Iron Oxide at 1500°C
Authors: JOHNSON R. E. , MUAN ARNULF
Published: June 2006

Phase relations in the system CaO‐MgO‐iron oxide were determined at 1500°C at two levels of oxygen pressure, 10–9 atm and 0.2 atm (air). Particular attention was directed toward de termining the maximum amount of iron oxide which may be tolerated in CaO‐MgO‐iron oxide bodies before a liquid phase forms under equilib rium conditions at the two chosen oxygen pres sures. Inferences are made regarding the possible bearing of the results on the perform ance of tar‐bonded dolomite brick used in steel making furnaces.
Electrical Conductivity in Fe1‐xO‐MgO Solid Solutions
Authors: HANSEN KENT W. , CUTLER IVAN B.
Published: June 2006

Solid solutions of magnesium oxide containing iron oxide in concentrations varying from a few percent to 100% were fabricated in polycrystalline form for studying the mechanism of electrical conduction. These semiconductors were ohmic in the range 0 to 10 v/cm, conducted by hole transfer, and showed reproducible conductivity data from room temperature to about 300°C. The conductivity of these solid solutions increases with increasing Fe3+ concentration. The electrical conductivity is also dependent on the total iron oxide content, decreasing rapidly (nonlinear dependence) as Fe1‐xO is diluted with MgO. The activation energy for electrical conduction varies from 0.1 to about 0.5 ev for the dilute solid solutions (less than about 15 cation % iron).