The Effects of Mergers on Prices, Costs, and Capacity Utilization in the U.S. Air Transportation Industry, 1970-84

We analyze the effect of mergers on various aspects of airline performance during the period 1970-84, using a panel data set constructed by Caves et al. Estimates derived from a simple "matched pairs" statistical model indicate that these mergers were associated with reductions in unit cost. The average annual rate of unit cost growth of carriers undergoing merger was 1.1 percentage points lower, during the five-year period centered on the merger, than that of carriers not involved in merger. Almost all of this cost reduction appears to have been passed on to consumers. Part of the cost reduction is attributable to mergerrelated declines in the prices of inputs, particularly labor, but about two-thirds of it is due to increased total factor productivity. One source of the productivity improvement is an increase in capacity utilization (load factor).

Multipliers of embedded discs

We consider a number of examples of multiplier algebras on Hilbert spaces associated to discs embedded into a complex ball in order to examine the isomorphism problem for multiplier algebras on complete Nevanlinna-Pick reproducing kernel Hilbert spaces. In particular, we exhibit uncountably many discs in the ball of $\ell^2$ which are multiplier biholomorphic but have non-isomorphic multiplier algebras. We also show that there are closed discs in the ball of $\ell^2$ which are varieties, and examine their multiplier algebras. In finite balls, we provide a counterpoint to a result of Alpay, Putinar and Vinnikov by providing a proper rational biholomorphism of the disc onto a variety $V$ in $\mathbb B_2$ such that the multiplier algebra is not all of $H^\infty(V)$. We also show that the transversality property, which is one of their hypotheses, is a consequence of the smoothness that they require.Comment: 34 pages; the earlier version relied on a result of Davidson and Pitts that the fibre of the maximal ideal space of the multiplier algebra over a point in the open ball consists only of point evaluation. This result fails for $d = \infty$, and has necessitated some changes; to appear in Complex Analysis and Operator Theor

Radio-chemotherapy as a preoperative treatment for advanced rectal cancer. Evaluation of down-staging and morbidity

Background: The standard therapy for patients with clinically resectable rectal cancer is generally considered to be surgery, If the patient is diagnosed with advanced disease, postoperative radiochemotherapy (RCT) is usually recommended. In our study we aimed to investigate and analyze the effectiveness and toxicity of preoperative pelvic radiotherapy in combination with 5-fluorouracil (5-FU) in locally advanced rectal cancer. Patients and Methods: From June 1999 to September 2001 we evaluated 50 consecutive patients {[}37 male and 13 female; average age 65.1 (range 46-79.5) years] with locally advanced rectal carcinoma. 32 patients were staged as uT3, 14 as uT4, and 4 as uT2. Regarding N-staging, 22 patients were diagnosed as ONO. 2 patients had distant metastases, with liver metastases in both instances. Conformal irradiation was performed with a box technique 4-field technique) with a dose of 45 Gy (5 x 1.8 Gy per week for a total of 25 sessions). From days 1-5 and 29-33, all patients received 5-FU (500 mg/m(2) per day, as a continuous i.v. injection). Results: Remission was observed in 28 patients (56%), with down-staging of at least one T-stage. A better success rate was achieved for patients with deep-seated tumors (64% of the patients in this group). Complete remission was observed in 4 patients (8.0%) and progression in 3 (6.0%). 15 patients had no detectable change in tumor staging (30.0%). A surgical R0 resection could be achieved in 43 patients, an R1 resection (minimal margins in 7. Side effects and toxicity (common toxicity criteria) of RCT included grade I-II dysuria in 5 patients (10%), grade I-II diarrhea in 20 patients (40%), and severe diarrhea in 2 patients (4.0%). Grade I-II skin reaction was noticed in 22 patients (44.0%), severe skin reaction only in 1 patient. Regarding acute postoperative morbidity, abscess and fistula formation was noted in 8 patients (16.0%), with anastomosis leakage in 7 (14%). Conclusion: Preoperative radiotherapy appears to be a feasible therapeutic approach with moderate toxicity and the potential to induce down-staging. The data presented in this study confirm the preliminary reports on this neoadjuvant treatment

A Circumstellar Disc in a High-Mass Star Forming Region

We present an edge-on Keplerian disc model to explain the main component of the 12.2 and 6.7 GHz methanol maser emission detected toward NGC7538-IRS1 N. The brightness distribution and spectrum of the line of bright masers are successfully modeled with high amplification of background radio continuum emission along velocity coherent paths through a maser disc. The bend seen in the position-velocity diagram is a characteristic signature of differentially rotating discs. For a central mass of 30 solar masses, suggested by other observations, our model fixes the masing disc to have inner and outer radii of about 350 AU and 1000 AU.Comment: 11 pages, accepted for publication in ApJ Letter

Overlapping Resonances Interference-induced Transparency: The S0→S2/S1S_0 \to S_2/S_1 Photoexcitation Spectrum of Pyrazine

The phenomenon of "overlapping resonances interference-induced transparency" (ORIT) is introduced and studied in detail for the $S_0 \to S_2/S_1$ photoexcitation of cold pyrazine (C$_4$H$_4$N$_2$). In ORIT a molecule becomes transparent at specific wavelengths due to interferences between envelopes of spectral lines displaying overlapping resonances. An example is the $S_2\leftrightarrow S_1$ internal conversion in pyrazine where destructive interference between overlapping resonances causes the $S_0 \to S_2/S_1$ light absorption to disappear at certain wavelengths. ORIT may be of practical importance in multi-component mixtures where it would allow for the selective excitation of some molecules in preference to others. Interference induced cross section enhancement is also shown.Comment: 13 pages, 7 figure

Is There a Significant Difference Between the Results of the Coulomb Dissociation of 8B and the Direct Capture 7Be(p,g)8B Reaction?

Recent claims of the Seattle group of evidence of "slope difference between CD [Coulomb Dissociation] and direct [capture] results" are based on wrong and selective data. When the RIKEN2 data are included correctly, and previously published Direct Capture (DC) data are also included, we observe only a 1.9 sigma difference in the extracted so called "scale independent slope (b)", considerably smaller than claimed by the Seattle group. The very parameterization used by the Seattle group to extract the so called b-slope parameter has no physical foundation. Considering the physical slope (S' = dS/dE), we observe a 1.0 sigma agreement between slopes (S') measured in CD and DC, refuting the need for new theoretical investigation. The claim that S17(0) values extracted from CD data are approximately 10% lower than DC results, is based on misunderstanding of the CD method. Considering all of the published CD S17(0) results, with adding back an unconfirmed E2 correction of the MSU data, yields very consistent S17(0) results that agree with recent DC measurements of the Seattle and Weizmann groups. The recent correction of the b-slope parameter (0.25 1/MeV) suggested by Esbensen, Bertsch and Snover was applied to the wrong b-slope parameter calculated by the Seattle group. When considering the correct slope of the RIKEN2 data, this correction in fact leads to a very small b-slope parameter (0.14 1/MeV), less than half the central value observed for DC data, refuting the need to correct the RIKEN2 data. In particular it confirms that the E2 contribution in the RIKEN2 data is negligible. The dispersion of measured S17(0) is mostly due to disagreement among individual DC experiments and not due to either experimental or theoretical aspects of CD.Comment: Reference 12 amended with an important communication from Dr. Bertsc

Evolution of Broad-line Emission from Active Galactic Nuclei

Apart from viewing-dependent obscuration, intrinsic broad-line emission from active galactic nuclei (AGNs) follows an evolutionary sequence: Type $1 \to 1.2/1.5 \to 1.8/1.9 \to 2$ as the accretion rate onto the central black hole is decreasing. This spectral evolution is controlled, at least in part, by the parameter $L_{\rm bol}/M^{2/3}$, where $L_{\rm bol}$ is the AGN bolometric luminosity and $M$ is the black hole mass. Both this dependence and the double-peaked profiles that emerge along the sequence arise naturally in the disk-wind scenario for the AGN broad-line region.Comment: MNRAS, to be publishe

"The Effects of Mergers on Prices, Costs, And Capacity Utilization in the U.S. Air Transportation Industry, 1970-84"

We analyze the effect of mergers on various aspects of airline performance during the period 1970-84, using a panel data set constructed by Caves et al. Estimates derived from a simple "matched pairs" statistical model indicate that these mergers were associated with reductions in unit cost. The average annual rate of unit cost growth of carriers undergoing merger was 1.1 percentage points lower, during the five-year period centered on the merger, than that of carriers not involved in merger. Almost all of this cost reduction appears to have been passed on to consumers. Part of the cost reduction is attributable to merger-related declines in the prices of inputs, particularly labor, but about two-thirds of it is due to increased total factor productivity. One source of the productivity improvement is an increase in capacity utilization (load factor).