Energy and economic analysis of total energy systems for residential and commercial buildings

Energy and economic analyses were performed for an on-site power-plant with waste heat recovery. The results show that for any specific application there is a characteristic power conversion efficiency that minimizes fuel consumption, and that efficiencies greater than this do not significantly improve fuel consumption. This type of powerplant appears to be a reasonably attractive investment if higher fuel costs continue

In Vitro Studies on the Role of the Brain and Prothoracic Glands in the Pupal Diapause of Manduca Sexta

Pupal diapause in the tobacco horn worm

The release of the prothoracicotropic hormone in the tobacco hornworm, Manduca sexta, is controlled intrinsically by juvenile hormone

Pupal development is elicited early in the last larval instar of the tobacco hornworm, Manduca sexta (Johannson), by a precise temporal and quantitative increase in the haemolymph titre of 20-hydroxyecdysone. This increase in the titre is referred to as the pupal commitment peak, and it occurs once the titre of juvenile hormone (JH) has dropped. If the haemolymph titre of JH remains elevated at this time due to topical application of the hormone or of its analogue ZR512, commitment is delayed or inhibited in a dose-dependent manner. This delay or inhibition is due to the curtailment of the commitment peak in the ecdysteroid titre, which results from a failure of the prothoracic glands (PG) to increase the synthesis/secretion of the premoulting hormone, ecdysone. Since the PG from ZR512- and JH 1-treated larvae are capable of being activated in vitro by the prothoracicotropic hormone (PTTH), the effect of JH on the PG does not involve suppression of gland sensitivity to PTTH. The locus of the JH effect was determined to be the brain-retrocerebral complexes (Br-CC-CA), on the basis of experiments which tested the effect of implanted Br-CC-CA from pre-commitment larvae treated with JH on the occurrence of pupal commitment in head-ligated larval hosts. The implanted, JH-treated Br-CC-CA exhibited a delayed release of PTTH, and the effect was at concentrations of JH that were physiological. These results argue that JH functions to control the time during the last larval instar when pupal commitment occurs by dictating when PTTH will undergo gated release

Cellular changes in the prothoracic glands of diapausing pupae of Manduca sexta

Prothoracic glands from diapausing pupae of the tobacco hornworm, Manduca sexta, synthesize markedly less ecdysone in vitro in response to prothoracicotropic hormone (PTTH) than do glands from non-diapausing pupae. Impaired steroidogenesis is also observed in glands from diapausing animals exposed to agents that enhance ecdysone synthesis in non-diapausing pupal glands by increasing intracellular levels of cAMP (1-methyl-3-isobutylxanthine, dibutyryl cAMP, and the calcium ionophore A23187). In contrast, prothoracic glands from diapausing pupae synthesize significantly more cAMP in response to PTTH and A23187 than do those from non-diapausing pupae. These observations indicate that the PTTH-refractoriness characteristic of prothoracic glands during diapause results from a lesion in the steroidogenic pathway occurring beyond the level of the PTTH receptor-adenylate cyclase system. The diapause condition of the prothoracic glands (reduced ecdysone synthesis accompanied by enhanced cAMP formation) can be mimicked by extirpation of the brain of a non-diapausing pupa. Thus, cellular changes in the prothoracic glands associated with diapause may arise as a result of the absence of some factor produced by the pupal brain (e.g. PTTH)

Regulation of ecdysone biosynthesis in the tobacco hornworm, Manduca sexta: titre of the haemolymph stimulatory factor during the last larval instar

A recently isolated haemolymph protein appears to be an important regulator of ecdysone biosynthesis by prothoracic glands in Manduca sexta. Using a dose-response titration protocol, the haemolymph titre of this stimulatory factor was determined during the last larval instar. The titre was high (greater than 2.0 U ml-1) on days 0 and 1, then dropped significantly to 0.55 U ml-1 on day 2, and remained depressed until day 4. The titre of the stimulatory factor then increased to a peak of 1.62 U ml-1 on day 7, and remained elevated (approx. 1.1 U ml-1) until the end of the instar. A set of physical and biochemical criteria was used to confirm that the stimulatory activity present in haemolymph on different days of the instar represented the presence of the factor. The data are consistent with the hypothesis that fluctuations in the titre of the haemolymph stimulatory factor play a critical role in regulating ecdysone biosynthesis during larval-pupal development

NuSTAR Reveals the Comptonizing Corona of the Broad-Line Radio Galaxy 3C 382

Broad-line radio galaxies (BLRGs) are active galactic nuclei that produce powerful, large-scale radio jets, but appear as Seyfert 1 galaxies in their optical spectra. In the X-ray band, BLRGs also appear like Seyfert galaxies, but with flatter spectra and weaker reflection features. One explanation for these properties is that the X-ray continuum is diluted by emission from the jet. Here, we present two NuSTAR observations of the BLRG 3C 382 that show clear evidence that the continuum of this source is dominated by thermal Comptonization, as in Seyfert 1 galaxies. The two observations were separated by over a year and found 3C 382 in different states separated by a factor of 1.7 in flux. The lower flux spectrum has a photon-index of $\Gamma=1.68^{+0.03}_{-0.02}$, while the photon-index of the higher flux spectrum is $\Gamma=1.78^{+0.02}_{-0.03}$. Thermal and anisotropic Comptonization models provide an excellent fit to both spectra and show that the coronal plasma cooled from $kT_e=330\pm 30$ keV in the low flux data to $231^{+50}_{-88}$ keV in the high flux observation. This cooling behavior is typical of Comptonizing corona in Seyfert galaxies and is distinct from the variations observed in jet-dominated sources. In the high flux observation, simultaneous Swift data are leveraged to obtain a broadband spectral energy distribution and indicates that the corona intercepts $\sim 10$% of the optical and ultraviolet emitting accretion disk. 3C 382 exhibits very weak reflection features, with no detectable relativistic Fe K$\alpha$ line, that may be best explained by an outflowing corona combined with an ionized inner accretion disk.Comment: 8 pages, 8 figures, accepted by Ap

A monoclonal antibody to the insect prothoracicotropic hormone

The prothoracicotropic hormone (PTTH) is an insect cerebral peptide that stimulates the prothoracic glands to produce the steroid hormone ecdysone thus initiating molting and metamorphosis. "Big" PTTH, one of several molecular forms of the neurohormone, was isolated from brains of the tobacco hornworm Manduca sexta, and fractionated by high-pressure liquid chromatography (HPLC) for use in antibody production. A murine polyclonal antiserum and a monoclonal antibody (MAb) have been generated using this highly purified preparation of big PTTH. Antisera and hybridoma supernatants were screened with an indirect, brain whole-mount immunocytological assay, and antibody specificity was confirmed by immunocytological, ELISA, and functional criteria. In brain whole-mount preparations, the MAb (A2H5) and antiserum specifically immunostained the lateral protocerebral neurosecretory cells (L-NSC III), the prothoracicotropes, which produce PTTH. This immunostaining was blocked by preadsorbing the antibodies with big PTTH. Analysis of the elution of HPLC-fractionated big PTTH with an in vitro bioassay for the neurohormone and an ELISA employing the A2H5 MAb resulted in peaks of activity that were superimposable. Finally, the antiserum and A2H5 MAb inhibited big PTTH activation of the prothoracic glands to synthesize ecdysone in the in vitro bioassay for the neurohormone. With these specific antibodies, the organization of the PTTH neuroendocrine axis has been defined. It is now evident that both of the peptidergic neurons that comprise the L-NSC III are prothoracicotropes, and that the corpora allata are the neurohemal organs for the release of big PTTH into the hemolymph. This study indicates that these specific antibodies will be useful in investigations of numerous aspects of the biology of this cerebral neuroendocrine axis

A Switch in the Control of Growth of the Wing Imaginal Disks of Manduca sexta

Background: Insulin and ecdysone are the key extrinsic regulators of growth for the wing imaginal disks of insects. In vitro tissue culture studies have shown that these two growth regulators act synergistically: either factor alone stimulates only limited growth, but together they stimulate disks to grow at a rate identical to that observed in situ. It is generally thought that insulin signaling links growth to nutrition, and that starvation stops growth because it inhibits insulin secretion. At the end of larval life feeding stops but the disks continue to grow, so at that time disk growth has become uncoupled from nutrition. We sought to determine at exactly what point in development this uncoupling occurs. Methodology: Growth and cell proliferation in the wing imaginal disks and hemolymph carbohydrate concentrations were measured at various stages in the last larval instar under experimental conditions of starvation, ligation, rescue, and hormone treatment. Principal Findings: Here we show that in the last larval instar of M. sexta, the uncoupling of nutrition and growth occurs as the larva passes the critical weight. Before this time, starvation causes a decline in hemolymph glucose and trehalose and a cessation of wing imaginal disks growth, which can be rescued by injections of trehalose. After the critical weight the trehalose response to starvation disappears, and the expression of insulin becomes decoupled from nutrition. After the critical weight the wing disks loose their sensitivity to repression by juvenile hormone, and factors from the abdomen, bu