The LX-sigma Relation for Galaxies and Clusters of Galaxies

We demonstrate that individual elliptical galaxies and clusters of galaxies form a continuous X-ray luminosity---velocity dispersion (LX-sigma) relation. Our samples of 280 clusters and 57 galaxies have LX ~ sigma^4.4 and LX ~ sigma^10, respectively. This unified LX - sigma relation spans 8 orders of magnitude in LX and is fully consistent with the observed and theoretical luminosity---temperature scaling laws. Our results support the notion that galaxies and clusters of galaxies are the luminous tracers of similar dark matter halos.Comment: 11 pages, including 2 tables and 2 figures. Accepted for publication in The Astrophysical Journal Letters; the Letters version excludes Table 1, which is available in ASCII format at http://tdc-www.harvard.edu/lxsigm

Dwarf galaxies in the Dynamically Evolved NGC 1407 Group

The NGC 1407 Group stands out among nearby structures by its properties that suggest it is massive and evolved. It shares properties with entities that have been called fossil groups: the 1.4 magnitude differential between the dominant elliptical galaxy and the second brightest galaxy comes close to satisfying the definition that has been used to define the fossil class. There are few intermediate luminosity galaxies, but a large number of dwarfs in the group. We estimate there are 250 group members to the depth of our survey. The slope of the faint end of the luminosity function (reaching M_R = -12) is alpha = -1.35. Velocities for 35 galaxies demonstrate that this group with one dominant galaxy has a mass of 7 X 10^13 M_sun and M/L_R = 340. Two galaxies in close proximity to NGC 1407 have very large blueshifts. The most notable is the second brightest galaxy, NGC 1400, with a velocity of -1072 km/s with respect to the group mean. We report the detection of X-ray emission from this galaxy and from the group.Comment: final version to appear in MNRAS, URL for data include

Length-structured approach to fisheries stock assessment

Modern fishing fleets have the capacity to over-exploit fish stocks. Inaccurate assessments could overestimate the stock size and as a result Total Allowable Catches (TAC) are set too high for sustainable stock conservation. Fisheries management need robust and reliable stock assessments to ensure that the species and environmental effect of fishing is sustainable. Since the demand for ecosystem based approaches to management has increased, the needs for improved estimates of un-assessed abundance have risen. Managers simply need to know how many fish left in the see and how much to limit the fishermen to fish to have sustainable fisheries. Therefore, accurate assessment of the market as well as by-catch stocks and records of true landings and discards are critical aspects of the scientific advice to the fisheries managers to accurately set TACs. Here, we consider the marine species that are left un-assessed. That is because they cannot be assessed by the existing methods. We therefore sought to fill the key gap with this matter. This thesis has five key elements. First we reviewed the stock assessment method with the emphasis on the length-structured models. Second, we produced a population model (so called survey-landings model) to make the use of survey frequency data extracted from International Bottom Trawl Survey and total annual landed biomass from commercial reports. Third, within a twin-experiment context and sensitivity analysis the model was assessed for accuracy and robustness in variability in initial parameter values and observational noise. Forth, applying the survey-landings model the population dynamics of the North Sea haddock was assessed and the results were compared with the International Council for Exploitation of the Sea assessment. Fifth, after the model proved to be reliable it is used as an alternative for age- or catch-at-length model, the population of the North Sea grey gurnards were modelled with confidence. This model enabled un-assessed species such as grey gurnards to be modelled and assessed for the first time.Modern fishing fleets have the capacity to over-exploit fish stocks. Inaccurate assessments could overestimate the stock size and as a result Total Allowable Catches (TAC) are set too high for sustainable stock conservation. Fisheries management need robust and reliable stock assessments to ensure that the species and environmental effect of fishing is sustainable. Since the demand for ecosystem based approaches to management has increased, the needs for improved estimates of un-assessed abundance have risen. Managers simply need to know how many fish left in the see and how much to limit the fishermen to fish to have sustainable fisheries. Therefore, accurate assessment of the market as well as by-catch stocks and records of true landings and discards are critical aspects of the scientific advice to the fisheries managers to accurately set TACs. Here, we consider the marine species that are left un-assessed. That is because they cannot be assessed by the existing methods. We therefore sought to fill the key gap with this matter. This thesis has five key elements. First we reviewed the stock assessment method with the emphasis on the length-structured models. Second, we produced a population model (so called survey-landings model) to make the use of survey frequency data extracted from International Bottom Trawl Survey and total annual landed biomass from commercial reports. Third, within a twin-experiment context and sensitivity analysis the model was assessed for accuracy and robustness in variability in initial parameter values and observational noise. Forth, applying the survey-landings model the population dynamics of the North Sea haddock was assessed and the results were compared with the International Council for Exploitation of the Sea assessment. Fifth, after the model proved to be reliable it is used as an alternative for age- or catch-at-length model, the population of the North Sea grey gurnards were modelled with confidence. This model enabled un-assessed species such as grey gurnards to be modelled and assessed for the first time

Modelling and predicting patient recruitment in multi-centre clinical trials

One of the main concerns in multi-centre clinical trials is how to enrol an adequate number of patients during a specific period of time. Accordingly, the sponsors are keen to minimise the recruitment time for cost effectiveness purposes. This research tended to concentrate on forecasting the patients’ accrual time for the pre-arranged number of sample size by simulating an on-going trial. The method was to model the data from the recruitment frequency domain and apply the estimations derived from the frequency domain to predict the time domain. Whereas previous papers did not concentrate on variations of recruiting over centres, this research assumed that patient arrivals followed the Poisson process and let the parameter of the process vary as a Gamma distribution. Consequently, the Poisson-gamma mixed distribution was confirmed as the promising model of the frequency domain. Then with the help of the relationship between the Poisson process and the exponential distribution, accrual time was predicted assuming that the waiting time between patients followed the Gamma-exponential distribution. As the result of the project, a trial was simulated based on the estimated values derived from completed trials. The first part of the prediction estimated the expected average number of patients per centre per month in an on-going trial. The second part, predicted the length of time (in months) to enrol specific number of patients in the simulated trial

Demand Dispatch Control for Balancing Load with Generation

There are different methods to implement demand management. In this thesis, a Demand Side Frequency Droop is proposed to calculate the require power reduction. Moreover, Demand Dispatch (DD) can provide ancillary service to the grid and maintains the power system frequency. Besides, to improve the operation of DD, the renewable resources and the storage devices are integrated to the DD. The proposed methods in this thesis have been validated through PSCAD software simulation and MATLAB

Impact of Trace Element Ions and Fe2+ on Anaerobic Food Waste Digestion

In Canada, about $31 billion worth of food is wasted annually. This amount of food waste (FW) ends up in landfills where it is naturally broken down by bacteria and releases methane to the atmosphere, a powerful greenhouse gas (GHG) which is 21 times more harmful to the environment than carbon dioxide (CO2). This process can also be done in a controlled environment at wastewater treatment plants, in a process known as anaerobic digestion (AD). Diverting food waste from landfills to wastewater treatment facilities allows for the capture of the methane, which can be used as an energy source. Although AD is a relatively reasonable technology to treat food waste, digesters that take FW as the sole feedstock have been facing unstable performance and even process failure mainly because of the accumulation of volatile fatty acids (VFAs) which is linked to trace elements (TEs) deficiencies. TEs play a key role in stimulating the enzymatic activity of the methanogenic micro-organisms and enhancing metabolic pathways. In this study, the importance of trace element (TE) background levels, especially Fe in the inoculum utilized for the mesophilic FW anaerobic digestion was assessed, while single and mixed ionic TEs were supplemented to batch reactors. Primarily, series of specific methanogenic activity (SMA) tests was carried out with acetate as substrate to observe the effects of TE ions supplementation on methanogenic activity. Subsequently in the biomethane potential tests (BMP), where FW was inoculated with the sludge and the effects of TE ions supplementation on the methane yield, maximum specific methane production rate (SMPRmax), and hydrolysis rate constant (Kh) were determined. The experiments were conducted first with an Fe-rich sludge and then repeated with a low-Fe sludge. Finally, the results of the two studies were compared in terms of methane yield and digestion kinetic parameters. SMA tests with the Fe-rich inoculum showed that Fe2+ (50-400 mg/L), Ni2+ (0.5-2 mg/L), Co2+ (0.1-0.5 mg/L), and Se4+ (0.005-0.05 mg/L) had drastic negative impacts on methane production rates. Mo6+ (2-20 mg/L) was the only TE ion that did not significantly affect SMA rates. On the other hand, with the low Fe sludge, the same ionic TE concentrations (Se4+ concentrations ranged from 0.1 mg/L to 0.8 mg/L) did not affect the methane production rate but 5 mg Mo6+/L, 20 mg Mo6+/L, and 400 mg Fe2+/L addition increased the SMA rates by 28%, 22%, and 20%. Single and mixed ionic TE supplementation to the batch reactors with the Fe-rich sludge led to the same values of SMPRmax and Kh for TE dosed and control reactors, except for Fe2+ and Co2+ which reduced the Kh as well as Mo6+ which decreased the SMPRmax. Soluble ionic TE concentrations decreased significantly during the experiments. The estimated amount of free sulfides (S2-) was well below the S2- concentration required to precipitate all the TE ions i.e. Fe2+, Ni2+, Co2+, Mo6+, and Se4+, therefore co-precipitation and adsorption onto iron sulfide complexes potentially played a significant role in reducing the soluble ionic TEs. In the second experiment with low Fe sludge, Ni2+, Co2+, Mo6+, Se4+ and Fe2+ increased the biogas yield by 28%, 25%, 21%, 29%, 13%. In BMP tests however, Ni2+, Co2+, Mo6+, Se4+, and Fe2+ supplementation increased the methane yield (CH4 per gram VSFW) by 27%, 23%, 31%, 32%, 22%. This positive effect of methane production was never observed with AD of FW with Fe-rich sludge. Maximum specific methane production rates (based on the modified Gompertz model) as well as hydrolysis rate constants (Kh) resulted in the same values for all ionic TE dosed and control reactors. Exceptions were for Co2+ at 0.1 mg/L which reduced the Kh value by 33% as well as Fe2+ which at 100, 200, and 400 mg/L increased the Kh by 74%, 57%, and 42%, respectively. Moreover, all TEs decreased the digestion time (for 60% COD degradation) from 6.5 days (controls) to 2.5-4.5 days. Ni2++Co2++Se4+, Ni2++Co2++Mo6+, Mo6++Se4+, and Ni2++Co2+ increased the methane yield by 6%, 9% 12%, and 16%, respectively. Maximum specific methane production rates based on modified Gompertz model and Kh values were the same for TE added and control reactors. A comparison between the performance of anaerobic digestion of FW with the two types of sludge indicates that methanogenic activity, methane yields (in all cases), and hydrolysis rate constant (in the Fe2+ case) were improved significantly when TEs were added to the batch reactors with low Fe inoculum, potentially due to the very different levels of Fe in the two inoculums which increase TE bioavailability. Thus, supplementing TEs in AD should be accompanied with a trace element background check in the sludge to make sure that Fe concentrations are not at the levels to promote co-precipitation and/or adsorption of ionic TEs onto the abundant Fe sulfide precipitates

The NGC 5846 Group: Dynamics and the Luminosity Function to M_R=-12

We conduct a photometric and spectroscopic survey of a 10 sq. deg. region surrounding the nearby NGC 5846 group of galaxies, using the Canada-France-Hawaii and Keck I telescopes to study the population of dwarf galaxies as faint as M_R=-10. Candidates are identified on the basis of quantitative surface brightness and qualitative morphological criteria. Spectroscopic follow up and a spatial correlation analysis provide the basis for affirming group memberships. Altogether, 324 candidates are identified and 83 have spectroscopic membership confirmation. We argue on statistical grounds that a total 251 +/- 10 galaxies in our sample are group members. The observations, together with archival Sloan Digital Sky Survey, ROSAT, XMM-Newton, and ASCA data, suggest that the giant ellipticals NGC 5846 and NGC 5813 are the dominant components of subgroups separated by 600 kpc in projection and embedded in a 1.6 Mpc diameter dynamically evolved halo. The galaxy population is overwhelmingly early type. The group velocity dispersion is 322 km/s, its virial mass is 8.4 x 10^13 M_sun, and M/L_R = 320 M_sun/L_sun. The ratio of dwarfs to giants is large compared with other environments in the Local Supercluster studied and, correspondingly, the luminosity function is relatively steep, with a faint end Schechter function slope of \alpha_d = -1.3 +/- 0.1 (statistical) +/- 0.1 (systematic) at our completeness limit of M_R = -12.Comment: 17 pages; accepted for publication in the Astronomical Journa

Working Health Services Scotland: a four-year evaluation

Background: Working Health Service Scotland (WHSS) supports the self-employed and employees of small and medium-sized enterprises (SMEs) in Scotland with a health condition affecting their ability to work, who are either absent or at risk of becoming absent due to it. Aims: To evaluate the impact on health and work outcomes of WHSS clients over a 4-year period. Methods: Data were collected at enrolment, entry, discharge and follow-up at 3 and 6 months after discharge. Clients completed up to three validated health questionnaires at entry and discharge—EuroQol five dimensions (EQ-5D) and visual analogue scale (VAS); Hospital Anxiety and Depression Scale (HADS); and Canadian Occupational Performance Measure (COPM). Results: A total of 13463 referrals occurred in the 4-year period; 11748 (87%) were eligible and completed entry assessment and 60% of the latter completed discharge paperwork. The majority of referrals were due to musculoskeletal conditions (84%) while 12% were referred with mental health conditions. Almost a fifth (18%) of cases were absent at entry and back at work at discharge. Work days lost while in WHSS was associated with age, length of absence prior to entering WHSS, primary health condition and time in programme. All health measures showed significant improvements from entry to discharge. Improvement in general health was sustained at 3- and 6-month follow-up. Conclusions: The WHSS evaluation findings indicate that participation was associated with positive changes to health and return-to-work. The extent of the positive change in health measures and work ability can be highly important economically for employees and employers