Expected stock returns and volatility in a production economy: a theory and some evidence

The sign of the relationship between expected stock market returns and volatility appears to vary over time, a result that seems at odds with basic notions of risk and return. In this paper we construct an economy where production involves the use of both labor and capital as inputs. We show that when capital investment is "sticky," the sign of the relation between stock market risk and return varies in accordance with the supply of labor but requires no time variation in preferences. In particular, we show that for asset market equilibria where firms face an elastic supply of labor, the traditional positive risk-return relation obtains. Conversely, a negative relation obtains for asset market equilibria where there is positive probability that labor supply will be highly inelastic. A nice feature of our model is that, unlike earlier work, the sign of the stock market risk-return relation can be associated with observable features of the business cycle. Post–World War II macroeconomic and stock return data are used to test the predictions from the model. Using standard measures of stock market volatility, our results provide support for a stock market risk-return relation that is negative at the peaks of business cycles and positive at the troughs.Stock market ; Risk ; Production (Economic theory) ; Business cycles

Expected stock returns and volatility in a production economy: a theory and some evidence

The sign of the relationship between expected stock market returns and volatility appears to vary over time, a result that seems at odds with basic notions of risk and return. In this paper we construct an economy where production involves the use of both labor and capital as inputs. We show that when capital investment is "sticky," the sign of the relation between stock market risk and return varies in accordance with the supply of labor but requires no time variation in preferences. In particular, we show that for asset market equilibria where firms face an elastic supply of labor, the traditional positive risk-return relation obtains. Conversely, a negative relation obtains for asset market equilibria where there is positive probability that labor supply will be highly inelastic. A nice feature of our model is that, unlike earlier work, the sign of the stock market risk-return relation can be associated with observable features of the business cycle. Post–World War II macroeconomic and stock return data are used to test the predictions from the model. Using standard measures of stock market volatility, our results provide support for a stock market risk-return relation that is negative at the peaks of business cycles and positive at the troughs

Intrinsic Brightness Temperatures of AGN Jets

We present a new method for studying the intrinsic brightness temperatures of the parsec-scale jet cores of Active Galactic Nuclei (AGN). Our method uses observed superluminal motions and observed brightness temperatures for a large sample of AGN to constrain the characteristic intrinsic brightness temperature of the sample as a whole. To study changes in intrinsic brightness temperature, we assume that the Doppler factors of individual jets are constant in time as justified by their relatively small changes in observed flux density. We find that in their median-low brightness temperature state, the sources in our sample have a narrow range of intrinsic brightness temperatures centered on a characteristic temperature, T_int = 3 x 10^10 K, which is close to the value expected for equipartition, when the energy in the radiating particles equals the energy stored in the magnetic fields. However, in their maximum brightness state, we find that sources in our sample have a characteristic intrinsic brightness temperature greater than 2 x 10^11 K, which is well in excess of the equipartition temperature. In this state, we estimate the energy in radiating particles exceeds the energy in the magnetic field by a factor of ~ 10^5. We suggest that the excess of particle energy when sources are in their maximum brightness state is due to injection or acceleration of particles at the base of the jet. Our results suggest that the common method of estimating jet Doppler factors by using a single measurement of observed brightness temperature and/or the assumption of equipartition may lead to large scatter or systematic errors in the derived values.Comment: 4 pages, 2 figures, Accepted to Appear in ApJ Letter

ARCADE 2 Measurement of the Extra-Galactic Sky Temperature at 3-90 GHz

The ARCADE 2 instrument has measured the absolute temperature of the sky at frequencies 3, 8, 10, 30, and 90 GHz, using an open-aperture cryogenic instrument observing at balloon altitudes with no emissive windows between the beam-forming optics and the sky. An external blackbody calibrator provides an {\it in situ} reference. Systematic errors were greatly reduced by using differential radiometers and cooling all critical components to physical temperatures approximating the CMB temperature. A linear model is used to compare the output of each radiometer to a set of thermometers on the instrument. Small corrections are made for the residual emission from the flight train, balloon, atmosphere, and foreground Galactic emission. The ARCADE 2 data alone show an extragalactic rise of $50\pm7$ mK at 3.3 GHz in addition to a CMB temperature of $2.730\pm .004$ K. Combining the ARCADE 2 data with data from the literature shows a background power law spectrum of $T=1.26\pm 0.09$ [K] $(\nu/\nu_0)^{-2.60\pm 0.04}$ from 22 MHz to 10 GHz ($\nu_0=1$ GHz) in addition to a CMB temperature of $2.725\pm .001$ K.Comment: 11 pages 5 figures Submitted to Ap

Boston Hospitality Review: Winter 2017

Table of contents: Family, Team or Something Else? by John Murtha -- Kitchen Organization in Full-Service Restaurants: Reducing Heat and Stress by Peter Szende and Justin Cipriano -- Rules of Engagement: Building Brand Relationships by Alex Friedman -- Corporate Social Responsibility in the Hospitality Sector by Manisha Singal and Yinyoung Rhou -- “Hold on, I have to post this on Instagram”: Trends, Talk, and Transactions of the Experiential Consumer by Steve Kent -- C-corporation Hotels vs. Hotel-REITs: A Theoretical and Practical Comparison by Tarik Dogru -- Sisters in Restaurant Success: A History of The Maramor by Jan WhitakerFamily, Team or Something Else? by John Murtha -- Kitchen Organization in Full-Service Restaurants: Reducing Heat and Stress by Peter Szende and Justin Cipriano -- Rules of Engagement: Building Brand Relationships by Alex Friedman -- Corporate Social Responsibility in the Hospitality Sector by Manisha Singal and Yinyoung Rhou -- “Hold on, I have to post this on Instagram”: Trends, Talk, and Transactions of the Experiential Consumer by Steve Kent -- C-corporation Hotels vs. Hotel-REITs: A Theoretical and Practical Comparison by Tarik Dogru -- Sisters in Restaurant Success: A History of The Maramor by Jan Whitake

Radiation from a Charge Uniformly Accelerated for All Time

A recent paper of Singal [Gen. Rel. Grav. 27 (1995), 953-967] argues that a uniformly accelerated particle does not radiate, in contradiction to the consensus of the research literature over the past 30 years. This note points out some questionable aspects of Singal's argument and shows how similar calculations can lead to the opposite conclusion.Comment: LaTeX, 9 pages, to appear in General Relativity and Gravitatio

ARCADE 2 Observations of Galactic Radio Emission

We use absolutely calibrated data from the ARCADE 2 flight in July 2006 to model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure in the data is consistent with a superposition of free-free and synchrotron emission. Emission with spatial morphology traced by the Haslam 408 MHz survey has spectral index beta_synch = -2.5 +/- 0.1, with free-free emission contributing 0.10 +/- 0.01 of the total Galactic plane emission in the lowest ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the polar caps using either a simple plane-parallel model with csc|b| dependence or a model of high-latitude radio emission traced by the COBE/FIRAS map of CII emission. Both methods are consistent with a single power-law over the frequency range 22 MHz to 10 GHz, with total Galactic emission towards the north polar cap T_Gal = 0.498 +/- 0.028 K and spectral index beta = -2.55 +/- 0.03 at reference frequency 1 GHz. The well calibrated ARCADE 2 maps provide a new test for spinning dust emission, based on the integrated intensity of emission from the Galactic plane instead of cross-correlations with the thermal dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is fainter than predicted by models without spinning dust, and is consistent with spinning dust contributing 0.4 +/- 0.1 of the Galactic plane emission at 22 GHz.Comment: 10 poges, 9 figures. Submitted to The Astrophysical Journa

Direct Distance Measurements to Superluminal Radio Sources

We present a new technique for directly measuring the distances to superluminal radio sources. By comparing the observed proper motions of components in a parsec scale radio jet to their measured Doppler factors, we can deduce the distance to the radio source independent of the standard rungs in the cosmological distance ladder. This technique requires that the jet angle to the line of sight and the ratio of pattern to flow velocities are sufficiently constrained. We evaluate a number of possibilities for constraining these parameters and demonstrate the technique on a well defined component in the parsec scale jet of the quasar 3C279 (z = 0.536). We find an angular size distance to 3C279 of greater than 1.8 (+0.5,-0.3) n^{1/8} Gpc, where n is the ratio of the energy density in the magnetic field to the energy density in the radiating particles in that jet component. For an Einstein-de Sitter Universe, this measurement would constrain the Hubble constant to be H < 65 n^{-1/8} km/s/Mpc at the two sigma level. Similar measurements on higher redshift sources may help discriminate between cosmological models.Comment: 18 pages, 8 figures, to be published in The Astrophysical Journa

Insights from within activity based learning (ABL) classrooms in Tamil Nadu, India: Teachers perspectives and practices

Quality has been an Education for All (EFA) goal since the 2000 Dakar framework positioned it ‘at the heart of education’ as a fundamental determinant of student enrolment, retention and achievement. Over the years, classroom pedagogy has been consistently regarded as ‘the crucial variable for improving learning outcomes’ (e.g., Hattie, 2009) and is thus seen as critical to reforms aimed at improving educational quality (UNESCO, 2005 p.152). The quality of teacher–pupil classroom interaction remains of central importance, rather research evidence (e.g., Borich, 1996) suggests that it is the single most important factor accounting for wide variation in the learning attainments of students who have used the same curriculum materials and purportedly experienced similar teaching methods. Other more recent studies (e.g., Aslam and Kingdon, 2011) have also reported that teacher ‘process’ variables have a more significant impact on student achievement than standard background characteristics. In the current era of the ‘global learning crisis’ (UNESCO, 2014) many developing economies have embarked on major pedagogical reforms. In India, the notion of energising schools and transforming classrooms has received unprecedented attention in the last 15 years. A number of programmes have been introduced in various states to provide meaningful access (Jandhyala and Ramachandran, 2007). The Activity Based Learning (ABL) Programme is one such effort to change the nature of teaching and learning in mainstream classrooms. In a national context, where there are innumerable on-going efforts aimed at pedagogical reform, ABL is hailed as a success story in terms of replication of a small model to a grand scale. From modest beginnings in 2003 in 13 Chennai (the capital city of Tamil Nadu) schools, ABL was rolled out in a phased manner across the entire state of Tamil Nadu for all children in classes 1–4, in all government and aided schools. The last few years have witnessed its adaptation under various guises in several other Indian states, such as Ekalavya in Madhya Pradesh, Digantar in Rajasthan and Nali Kali in Karnataka. Efforts to promote it internationally in other parts of the developing world, such as Ghana, Bangladesh, Ethiopia and Mozambique (Fennell and Shanmugam, 2016)have also been made. Though as Nudzor et al., 2015 note it has been met with mixed success in the case of Ghana. Nonetheless, ABL is an interesting programme to examine given its rapid growth and international outreach.The project was funded by Department for International Development (DFID, India)

ARCADE: Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission

The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a balloon-borne instrument designed to measure the temperature of the cosmic microwave background at centimeter wavelengths. ARCADE searches for deviations from a blackbody spectrum resulting from energy releases in the early universe. Long-wavelength distortions in the CMB spectrum are expected in all viable cosmological models. Detecting these distortions or showing that they do not exist is an important step for understanding the early universe. We describe the ARCADE instrument design, current status, and future plans.Comment: 12 pages, 6 figures. Proceedings of the Fundamental Physics With CMB workshop, UC Irvine, March 23-25, 2006, to be published in New Astronomy Review