To eliminate uncertainties introduced by extinction by dust in the optical, we examine to what extent the radio continuum (RC) can probe star formation in dwarf galaxies. Star formation (SF) drives galaxy formation and evolution; acquiring accurate measurements of SF thus becomes crucial in order to understand galaxies. As radio technology improves further, RC surveys will probe the fainter, more quiescent regime of the radio sky. Having a robust manner by which to convert RC luminosities to star formation rate (SFR) has the potential to provide millions of independent SFR measurements out to intermediate redshifts. In order to calibrate the RC to infer SFR, the 40 dwarf galaxies that make up the LITTLE THINGS sample were chosen as the bedrock of the thesis due to the large range of galactic parameters that they cover. RC observations of these galaxies were taken with the VLA between L- and Ka-band (1-33GHz) using the B-, C-, and Darrays, yielding images with 3-10" resolution and rms noise levels between 3 and 15 μJy beam⁻¹. On a global scale, 27 out of the 40 dwarf galaxies exhibited RC emission above the detection threshold, 17 of which were new RC detections. The general picture is an interstellar medium (ISM) largely void of RC emission, interspersed by isolated pockets of RC associated with SF regions; this general picture agreed with what was expected given current models of dwarf galaxies - weaker magnetic fields in the ISM leading to a higher escape of CRe (and resulting reduction in RCNTh emission). This was also backed-up by the relatively low RCNTh fraction - 61 ± 7% at C-band. The observed RC-SFR relation was calibrated to allow the observed RC luminosity of a gas rich dwarf galaxy to be used to infer the SFR; the calibration takes the form SFR [M⊙ yr⁻¹] = 5 x 10⁻¹⁸(RC [WHz⁻¹])0.85. On a resolved basis, only the RCNTh was examined - this is because whether scales of 1 pc, or 1 kpc are investigated, the relationship between the Hα (current SF) and RCTh was not expected to change. Calibrating the resolved RCNTh-SFR relation was best done when using discrete SF regions which varied from 10s up to 100s of pc in size. On these scales, the calibration allows the SFR to be inferred from an observed RCNTh luminosity, and takes the form SFR [M⊙ yr⁻¹] = 1.36 x 10⁻²³(LNTh [WHz⁻¹])1.15. This calibration, however, is only valid for resolved regions forming stars at a rate ≳ 2 x 10⁻⁴M⊙ yr⁻¹. Despite the low flux densities of RCNTh measured from these discrete SF regions, the RCNTh still works well as a SFR tracer whereas Hα, which is largely dependent on stars with mass ≳ 18M⊙, and is thus dependent on the high mass tail of the stellar IMF, will suffer from stochasticity. In a few dwarfs, the equipartition magnetic field strength reaches as high as 30 μG in multiple 100 pc regions, and in one case, 70 μG. However, generally, the weaker magnetic fields in the ISM give the CRe longer lifetimes, and thus more time to be advected out of the galaxy with the magnetic fields frozen into the gas in outflows, or diffuse. This explains in part the lack of RCNTh emission observed in the ISM of dwarf galaxies. Through implementing a simple galactic CRemodel, itwas found that the RCNTh emission associated with the CRe can be used as a SF tracer from approximately 5 up to 70Myr following a burst of SF, while RCTh can be used in its absence prior to 5Myr. The RCNTh luminosity reaches its peak approximately 55Myr after the SF episode, but actually remains nearly constant over the 60Myr following the SF episode, highlighting its potential to be used to infer SFR. The CRemodel also tracked the evolution of the RCNTh spectral index with time. Between values of about -0.4 and -0.7, the RCNTh spectral index can be calibrated to infer the time elapsed since a burst of SF through t[Myr] = -25αNTh. RCNTh spectral indices of -0.8 are consistent with ages between 20 and 55Myr, suggesting that the oft observed spectral index of -0.8 in galaxies may come from the fact that C-band RCNTh emission is dominated by the steep spectral indices of -0.8 from these older SF regions (20-55Myr). For the galaxies that displayed RCNTh emission that was bright enough and sufficiently well resolved, a spectral decomposition of the RC spectrum was performed to infer Hα-independent RCTh, RCNTh, and RCNTh spectral index maps. The spectral decomposition showed DDO50 and NGC1569 to have a low thermal fraction of 23% and 10%, respectively, at C-band, while NGC2366 and NGC4214 were shown to have higher thermal fractions of 48% and 66%, respectively. In summary, dwarf galaxies are not only faint in the RC due to their lower SF activity, but they are also fainter than expected due to CRe escape. Nonetheless, the RC can be used to probe SF in dwarf galaxies not only on a global scale, but also within discrete SF complexes 10s to 100s of pc in size. Theoretically, the RC can be used right from the onset of a burst of SF, where RCTh will dominate, up to ~ 70Myr, at which point RCNTh will dominate. Calibrated by the RC observations in this thesis, both resolved and global SFRs of gas rich, low mass galaxies can be inferred with an uncertainty of ±0.2 dex; the relations allow SFRs of between approximately 2x10⁻⁴ and 0.1M⊙ yr⁻¹ to be inferred.

Recent observations at the James Clerk Maxwell Telescope (JCMT) and elsewhere have identified a class of very deeply embedded, possibly protostellar, sources which are not associated with any of the traditional indicators of star formation, such as HII regions and near-infrared emission, but which do lie close to otherwise isolated H2O masers. This thesis describes a search, based on catalogues of known water maser positions, for new deeply embedded cores similar to those found in S106 and M17. In addition to millimetre molecular line and submillimetre continuum observations, 22 GHz and 8 GHz radio observations have been made of a number of the sources in order to obtain more accurate maser positions and to search for any associated compact HII regions. Observing sources such as these in less active star forming regions provides a cleaner environment in which to examine the maser excitation and the ongoing process of star formation. A sample of 44 water maser sources was observed from which submillimetre continuum emission was detected from 40 (91 per cent). The most striking feature of the data is the close association of the masers with the submillimetre cores: the data are consistent with masers occurring within 6000 AU of the embedded core. The results can be summarised as follows: o High temperature gas has been detected, and most of the submillimetre cores have mean densities greater than 10^6 /cm^3. o The masers have low velocities with respect to the molecular cloud and are uniformly distributed within 6600 AU of the submillimetre core. o The isotropic maser luminosity is proportional to the far-infrared luminosity over more than 5 orders of magnitude. o There is no obvious correlation between the near-infrared spectral class and the maser emission. o Where a radio spectral index is known the majority of sources are optically thin HII regions. The bulk of the remainder are undetected and have a flux density less than 1 mJy. o Masers not associated directly with a submillimetre core show explicit evidence for shocks. Embedded cores \emph{have} been detected with this survey and the maser emission is consistent with collisionally excited pump models.

Until recently, obtaining rest-frame optical spectra of galaxies at z > 1 was a time consuming and challenging observation due to the difficult nature of near-infrared (near-IR) spectroscopy. However, with the advent of second generation ground-based near-IR spectrographs (e.g. KMOS, MOSFIRE), and the new low resolution near-IR grisms on the Hubble Space Telescope (HST), we have entered a new era in the study of high redshift galaxies. This thesis explores the physical properties of star-forming galaxies in the redshift range 1 < z < 3 by utilising a custom reduction of the 3D-HST near-IR grism spectroscopic survey. One of the most important observational constraints on the evolution of galaxies is the mass-metallicity relation (MZR), which is sensitive to both the star-formation history and various inflow/outflow processes. I use the 3D-HST spectra to provide a new constraint on the MZR at 2:0 < z < 2:3, and moreover measure the O/H abundance directly from the oxygen and hydrogen emission lines ([OII], [OIII] and Hβ) as opposed to the more common method at high redshift of inferring O/H from the N/H ratio (via [NII] and Hα). I show that the traditional form of the MZR is recovered from the 3D-HST data, with metallicity increasing with the stellar mass of a galaxy. However, the absolute metallicity values I derive are inconsistent with previous N/H-based measurements of metallicity at these redshifts. Moreover, I show that the 3D-HST data is inconsistent with the `fundamental metallicity relation' (FMR), and that, contrary to previous claims, this local Universe relation may not hold out to z & 2. To investigate this metallicity discrepancy further, I measure the evolution of the [OIII]/Hβ nebular emission line ratio in the 3D-HST spectra over the redshift range 1:3 < z < 2:3. I compare this observed line ratio evolution with state-of-the- art theoretical models which take into account the independent evolution of the ionization parameter, electron density and metallicity of star-forming regions with redshift. The homogeneous 3D-HST dataset allows me to perform a consistent analysis of this evolution which takes into account line luminosity selection effects. I show that, according to models, the observed [OIII]/Hβ evolution cannot be accounted for by pure metallicity evolution. Instead I am able to infer that the line ratio evolution is more consistent with, at the very least, an evolution to stronger ionizing conditions at high redshift, and perhaps even denser star-forming regions. I explore how this result can also explain the observed discrepancy between high redshift metallicity measurements. In light of this finding, I revisit the MZR at z >~ 2 and employ a purely theoretical approach to inferring metallicities from nebular lines, which is able to account for an evolution in ionization conditions. I then use a selection of galaxies from the local Universe, which mimic the properties of high redshift galaxies, to derive a more robust ionization sensitive, conversion, between N/H and O/H. With this new conversion which I am able to bring the previous inconsistent metallicity measurements at z >~ 2 back into agreement. Finally, I am able to show that, in this new formalism, the metallicity evolution between z = 2 and z = 3 is perhaps not as large as previously reported. To conclude I discuss ongoing work as part of the KMOS Deep Survey (KDS) being undertaken with the near near-IR Multi-Object Spectrograph KMOS on the VLT. I describe the observations and data reduction that has been completed to date and describe how this instrument will allow me to extend the work presented in this thesis to z > 3. I also introduce FIGS, a new HST near-IR grism survey seeking to spectroscopically identify galaxies at 5:5 < z < 8:5 and work I have begun in exploring this dataset.

Glyphosate-based herbicides are the dominant pesticide on the market and are utilized worldwide in both the agricultural and forestry industries. Their prevalence comes at a time when concern over the potential effects of pesticide application in amphibian spawning grounds is growing. The primary goal of this thesis was to determine if the glyphosate-based herbicide WeatherMax® has the potential to disrupt sexual differentiation and growth in the wood frog (Lithobates sylvaticus) in a pulse exposure at the predicted maximal environmental concentration (PMEC) of 2.88 mg acid equivalent per liter. This was carried out in laboratory, mesocosm and in-situ field exposures, in an attempt to determine how a potential disruption might vary between experimental environments. In this study, tadpoles from three split-wetlands targeted at the PMEC for WeatherMax were found to display no significant change in survival or growth, however gene expression of several genes involved in steroidogenesis during sexual differentiation (cyp19, cyp17, star, foxl2) were found to be affected. The effects on these genes appeared to be dependant on the exposure concentration of WeatherMax in each wetland, which varied even though all three wetlands were meant to target the PMEC. The wetland that was measured as having the highest herbicide concentration (PMEC 13) was found to have a female biased sex ratio. The results found in the field varied from those found in the more artificial exposures. In the laboratory the PMEC of WeatherMax experienced complete mortality, whereas in the mesocosms survival was not significantly affected. Sex ratios were unaffected in the laboratory, however at the PMEC there was a significant male bias in the mesocosms. The discrepancies in the results obtained from the different exposure types highlights the importance of real world exposures. That the same concentration that caused complete mortality in the laboratory caused sublethal effects in the field is of importance as it denotes that these endpoints may not be easily investigated in these synthetic exposures. This project is a part of the Long Term Experimental Wetlands Area (LEWA) and contributes to the body of information amassed therein on the impact of a glyphosate-based herbicide on amphibians in a wetland ecosystem.

The work in this thesis was undertaken to explore both the effect of heteroatoms on the semiconducting properties of star-shaped thienoacenes, and to expand the scope of these materials to fields outside of organic semiconductors. Overall, new star-shaped molecules were prepared with a view towards applications such as thin film transistors, as the organic linker component in metal-organic frameworks, and as ligands that could coordinate to transition metals through the sulfur atom. The first chapter describes the properties of star-shaped molecules, the theory underlying their semiconducting behaviour, and the previous work that motivated the research contained herein. The second chapter of this thesis outlines the synthetic methodology that was utilized to achieve the molecular targets, as well as the characterization techniques that are used to reveal the properties of organic semiconductors. The third chapter of this thesis describes the synthesis and optoelectronic properties of novel nitrogen-containing semiconductor molecules called thienoacridines, and their comparison to carbon-and-sulfur based analogues, thienoanthracenes. The fourth and fifth chapters concern the synthesis of functionalized star shaped thienylbenzene molecules. In Chapter 4, these molecules are decorated with carboxylic acid groups so that they may act as tetrapodal MOF linkers. In Chapter 5, they are equipped with N-aryl(azomethine)thiophene moieties to explore sulfur coordination and act as ligands. The sixth chapter provides conclusion to this work, and possible future directions of the research conducted herein.

In this thesis I present work done on the subject of star formation through the study of infrared dark clouds. We studied the velocity fields in several IRDCs using spectral line mapping. We also performed observations of a high density tracer and its deuterated counterpart. These observations allow me to assess the kinematics of these clouds and the evolutionary state of the observed targets. The sample observed is an important starting point for the search of early and quiescent high-mass regions. We mapped several IRDCs using the 22m ATNF Mopra Telescope in high-density molecular tracers at 3 mm, HNC (1-0) and N2H+ (1-0). We present integrated intensity emission and velocity field maps of these IRDCs. The molecular emission in the maps matches well with the extinction seen in the mid-IR. For an IRDC-complex we see connecting emission in the whole filament. We calculate kinematic distances and masses of the IRDCs. The IRDCs typically display an ordered velocity field within the clouds. The mean velocity gradient of the sample was 0.4 km/s/pc. We show how this velocity gradient can mean gas flows within the cloud into the central regions in order to feed the central cores. We observed 54 cores in IRDCs using N2H+ (1-0) and (3-2) to determine the kinematics of the densest material, where stars will form. We also observed N2D+ (3-2) towards 29 of the brightest peaks to analyze the level of deuteration which is an excellent probe of the quiescent of the early stages of star formation. There were 13 detections of N2D+ (3-2). This is one of the largest samples of IRDCs yet observed in these species. The deuteration ratio in the sources with detected N2D+ (3-2) has a mean of 0.024 and reaches a maximum value of 0.14. For most of the sources the material traced by N2D+ and N2H+ (3-2) still has significant turbulent motions, however three objects show subthermal N2D+ velocity dispersion. Surprisingly the presence or absence of an embedded 70 micron source shows no correlation with the detection of N2D+ (3-2), nor does it correlate with any change in velocity dispersion or excitation temperature. Comparison with recent models of deuteration suggest evolutionary timescales of these regions of several freefall times or less.

Two analyses of data recorded in proton-proton collisions at the ATLAS detector in 2012 are presented in this thesis. The first pertains to the beam separation (van der Meer) scans required to calibrate the absolute luminosity. An estimate is made for the size of the correction needed to the standard van der Meer calibration method, which assumes that the proton bunch density profiles are factorisable. This is done by observing and modelling the evolution of various beam spot phenomena during the separation scans. The second analysis described is a series of measurements of the Z/gamma cross-section, differential in the phi star observable, for different ranges of the boson invariant mass and absolute rapidity. In particular the events in which the boson decays to electron-positron pairs are considered. The phi star observable is defined in terms of the well-measured lepton directions and enables a probe of initial state gluon radiation in the non-perturbative regime of QCD.

This thesis presents phenomenological studies of a state-of-the-art NNLL+NLO theoretical calculation of a novel collider observable known as 'phi star'. In these studies the 'phi star' observable, a measure of azimuthal decorrelation, is applied directly to the leptons in the production of massive lepton pairs in hadron collisions (the Drell-Yan process). This provides an alternate measure of the recoil of the massive vector boson (Z/gamma) against initial state QCD radiation, but with distinct experimental advantages over the traditional boson transverse momentum. Attention is focused on the small-'phi star' regime (the quasi-back-to-back regime) where the infrared dynamics of soft/collinear gluon emissions become important. These phenomenological studies are followed up with the presentation of a measurement of 'phi star' in 'Z to mu mu' events using 20.3 fb^-1 of collision data collected by the ATLAS experiment in 2012. Finally, studies directly related to the ATLAS absolute luminosity calibration by the van der Meer (vdM) method are presented, with the objective of elucidating the role of transverse linear beam correlation. In particular, I present studies using an analytical method I have developed in order to precisely extract individual beam information by way of studying phenomena pertaining to the luminous region during vdM scans. In addition, a dedicated study of the long- and short-term stabilities of the principal detectors for luminosity monitoring is also presented, along with an appropriate recalibration of these detectors.

This master's thesis deals with informed search algorithms. It's theoretical section summarizes basic theoretical ideas and terms which are related to this topic. It means especially discrete mathematics, graph theory, artificial intelligence and agent systems. Cardinal aim of this section is to provide theoretical analysis of search algorithms and to classify them into informed and uninformed classes. Theoretical section describes basic search strategies such as breadth first search, deep first search and modifications of these strategies, then it is focused on informed search algorithms, specifically A* (A-Star), IDA* (Iterative Deepening A-Star) and SMA* (Simplified Memory bounded A-star). It also describes topics related to informed search strategies -- heuristic functions and problem relaxation method. Given algorithms are analyzed in order to compare their time and space complexity. Main goal of practical part of this thesis is to design and implement software application, which will use informed and uninformed search strategies described in theoretical section. This application is intended to solve fifteen puzzle problem, so-called Lloyds fifteen puzzle game. First part of practical section analyses fifteen puzzle from mathematical and informatical perspective, then it examines possible implementation variants of algorithms and heuristics and proposes design of the application. Description of main interfaces and classes of the realized application follows. At the end of this section the analysis of informed algorithms and heuristics is performed using the implemented application and obtained results are compared to theoretical characteristics of these algorithms.

We report photometric measurements of a sodium resonance guide star against the daylight sky when observed through a tuned magneto-optical filter (MOF). The MOF comprises a sodium vapor cell in a kilogauss-level magnetic field between crossed polarizers and has a very narrow transmission profile at the sodium D-2 resonance of approximately 0.008 nm. Our observations were made with the 1.5 m Kuiper telescope on Mt. Bigelow, AZ, which has a separately mounted guide star laser projecting a circularly polarized single-frequency beam of approximately 6.5 W at 589.16 nm. Both the beam projector and the 1.5 m telescope were pointed close to zenith; the baseline between them is approximately 5 m. Measurements of the guide star were made on the morning of 2016 March 24 using an imaging camera focused on the beacon and looking through the full aperture of the telescope. The guide star flux was estimated at 1.20x10(6) photon/m(2)/s while at approximately 45 minutes after sunrise, the sky background through the MOF was 1100 photon/m(2)/s/arcsec(2). We interpret our results in terms of thermal infrared observations with adaptive optics on the next generation of extremely large telescopes now being built.