Every Seafarer Has a Primary Duty That May Provide the Basis of a Defense in a Personal Injury Action

A seafarer injured while in the service of a merchant ocean vessel is accorded three causes of action against his or her employer: 1) Jones Act negligence, 2) the warranty of seaworthiness, and 3) maintenance and cure. The latter two causes of action arise under general maritime law, the first is statutory. This article deals with a defense to a seafarer’s claims for Jones Act negligence and unseaworthiness. This defense, commonly known as the “Primary Duty Rule,” has been restated in numerous variations since its inception. This article examines the history and evolution of the Rule and suggests a restatement of the Rule for continued application in the defense of seafarer personal injury cases

A review of bovine Johne's disease control activities in 6 endemically infected countries

Mycobacterium avium subspecies paratuberculosis (MAP) is endemic in the bovine populations of many countries and can cause a significant reduction in animal welfare and production efficiency making control desirable. Effective control has proved very difficult to achieve despite multiple regionally coordinated programmes being in existence since the 1920s. The international community increasingly recognises the value in learning from the collective experiences of existing programmes to improve the effectiveness of control. The aim of this review is to outline key aspects of bovine Johne's disease control activities across 6 endemically infected countries to facilitate comparison of current international practice. The background, control activities and monitoring components of programmes in Australia, Canada, Denmark, the Netherlands, the United Kingdom and the United States of America were individually reviewed. Factual accuracy of each review was checked by individuals involved in the respective programmes before the reviews were condensed and combined into a single document presented here, with the complete reviews of each programme available as supplementary material. There was considerable heterogeneity in key aspects of control activity design including goals, responses to declining participation, herd classification, recommended control measures and associated test requirements. The data presented will be of interest to organisations that are involved in developing new or existing regionally coordinated BJD control activities

Cascaded wavelength conversions using four-wave mixing in semiconductor optical amplifiers

Wavelength conversion in wavelength-division multiplexed (WDM) communication systems would provide significant network performance improvement. Optoelectronic, cross-gain saturation, and cross phase saturation wavelength converters are candidate technologies that have been well characterized, however, they are not “transparent” to either bit-rate or modulation format. Complete transparency is offered only by ultrafast wave mixing techniques-in the present case four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs)

Polarization-independent wavelength conversion at 2.5 Gb/s by dual-pump four-wave mixing in a strained semiconductor optical amplifier

We give a general expression for the polarization dependence of the four-wave mixing (FWM) efficiency in the dual-pump configuration. This expression, along with some general properties of the FWM susceptibility tensor, is used to propose a simple scheme to generate a nearly (1.5-dB variation) polarization independent FWM converted signal. The viability of this scheme is verified in a wavelength conversion experiment at 2.5 Gb/s

The Role of RFamide-Related Peptide-3 in Age-Related Reproductive Decline in Female Rats.

Reproductive senescence, the point in time when females cease to show estrous cyclicity, is associated with endocrine changes in the hypothalamus, pituitary, and gonads. However, the mechanisms triggering this transition are not well understood. To gain a better understanding of the top-down control of the transition from reproductive competence to a state of reproductive senescence, we investigated middle-aged female rats exhibiting varying degrees of reproductive decline, including individuals with normal cycles, irregular cycles, and complete cessation of cycles. We identified hormonal changes in the brain that manifest before ovarian cycles exhibit any deterioration. We found that females exhibit an increase in RFamide-related peptide-3 (RFRP3) mRNA expression in the hypothalamus in middle age prior to changes in estrous cycle length. This increase is transient and followed by subsequent decreases in kisspeptin (KiSS1) and gonadotropin-releasing hormone (GnRH) mRNA expression. Expression of RFRP3 and its receptor also increased locally in the ovaries with advancing age. While it is well known that aging is associated with decreased GnRH release and downstream disruption of the hypothalamic-pituitary-gonadal (HPG) axis, herein, we provide evidence that reproductive senescence is likely triggered by alterations in a network of regulatory neuropeptides upstream of the GnRH system

Entry pathways of herpes simplex virus type 1 into human keratinocytes are dynamin- and cholesterol-dependent

Herpes simplex virus type 1 (HSV-1) can enter cells via endocytic pathways or direct fusion at the plasma membrane depending on the cell line and receptor(s). Most studies into virus entry have used cultured fibroblasts but since keratinocytes represent the primary entry site for HSV-1 infection in its human host, we initiated studies to characterize the entry pathway of HSV-1 into human keratinocytes. Electron microscopy studies visualized free capsids in the cytoplasm and enveloped virus particles in vesicles suggesting viral uptake both by direct fusion at the plasma membrane and by endocytic vesicles. The ratio of the two entry modes differed in primary human keratinocytes and in the keratinocyte cell line HaCaT. Inhibitor studies further support a role for endocytosis during HSV-1 entry. Infection was inhibited by the cholesterol-sequestering drug methyl-beta-cyclodextrin, which demonstrates the requirement for host cholesterol during virus entry. Since the dynamin-specific inhibitor dynasore and overexpression of a dominant-negative dynamin mutant blocked infection, we conclude that the entry pathways into keratinocytes are dynamin-mediated. Electron microscopy studies confirmed that virus uptake is completely blocked when the GTPase activity of dynamin is inhibited. Ex vivo infection of murine epidermis that was treated with dynasore further supports the essential role of dynamin during entry into the epithelium. Thus, we conclude that HSV-1 can enter human keratinocytes by alternative entry pathways that require dynamin and host cholesterol

Pilot study into milk haptoglobin as an indicator of udder health in heifers after calving

Mastitis, inflammation of the mammary gland, is often caused by intramammary infection with bacterial organisms. It impacts on dairy cattle welfare, production, udder health and longevity in the herd. Current detection methods for mammary inflammation and infection all have limitations, particularly for on-farm diagnosis of non-clinical mastitis after calving. Acute phase proteins have been suggested as alternative early indicators of the disease and can potentially be used as cow-side test with results in real time. In this study, milk haptoglobin concentrations were investigated over the first week postpartum to explore haptoglobin's potential as indicator of udder health in dairy heifers. Haptoglobin concentration was highest on day 3 of lactation, and was positively correlated with somatic cell count, a commonly used marker of inflammation (rs=0.68). Haptoglobin level was also associated with bacteriological culture results, a key indicator of infection status, whereby median haptoglobin concentration on days 3 and 5 was higher in quarters that were infected at calving than quarters that were non infected at calving. Sensitivity and specificity of haptoglobin concentration as indicator of infection were low, both for lenient and strict culture-based definitions of intramammary infection (57 or 60% and 61 or 63%, respectively). Although haptoglobin was a poor biomarker for intramammary infection with coagulase negative staphylococci in heifers during the first week after calving, it may have value as an indicator of major pathogen infections, particularly in large scale dairy herds where pre-partum heifers are managed off-site

Cross talk penalty in two-channel wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier

A crucial function in wavelength-division multiplexed (WDM) all-optical networks is a wavelength converter. This function enhances wavelength routing options and improves network reconfigurability. Here we present a systematic study of the cross talk penalty as a function of the pump-to-signal power ratio for two 2.5-Gbit/s ASK channels separated by 1.5 nm

Wavelength conversion for WDM communication systems using four-wavemixing in semiconductor optical amplifiers

Four-wave mixing (FWM) in semiconductor optical amplifiers is an attractive mechanism for wavelength conversion in wavelength-division multiplexed (WDM) systems since it provides modulation format and bit rate transparency over wide tuning ranges. A series of systems experiments evaluating several aspects of the performance of these devices at bit rates of 2.5 and 10 Gb/s are presented. Included are single-channel conversion over 18 nm of shift at 10 Gb/s, multichannel conversion, and cascaded conversions. In addition time resolved spectral analysis of wavelength conversion is presented