Effects of post-fire logging on forest surface air temperatures in the Siskiyou Mountains, Oregon, USA

Following stand-replacing wildfire, post-fire (salvage) logging of fire-killed trees is a widely implemented management practice in many forest types. A common hypothesis is that removal of fire-killed trees increases surface temperatures due to loss of shade and increased solar radiation, thereby influencing vegetation establishment and possibly stand development. Six years after a wildfire in a Mediterranean-climate mixed-conifer forest in southwest Oregon, USA, we measured the effects of post-fire logging (> 90 per cent dead tree (snag) removal) on growing season surface air temperatures. Compared with unlogged severely burned forest, post-fire logging did not lead to increased maximum daily surface air temperature. However, dead tree removal was associated with lower nightly minimum temperatures (similar to 1 degrees C) and earlier daytime heating, leading to a 1-2 degrees C difference during the warming portion of the day. Effects varied predictably by aspect. The patterns reported here represent a similar but muted pattern as previously reported for microclimatic changes following clear-cutting of green trees. Effects of microsites such as tree bases on fine-scale temperature regimes require further investigation

High-power single-frequency operation and efficient intracavity frequency doubling of a Nd:YAG ring laser, end-pumped by a 20W diode bar

The re-shaped output from a 20W cw diode-bar is used to longitudinally pump a Nd:YAG ring laser, resulting in a single-frequency output at 1.06µm of 5W and an intracavity frequency-doubled output at 532nm of 3W

Residual Momentum

Conventional momentum strategies exhibit substantial time-varying exposures to the Fama and French factors. We show that these exposures can be reduced by ranking stocks on residual stock returns instead of total returns. As a consequence, residual momentum earns risk-adjusted profits that are about twice as large as those associated with total return momentum; is more consistent over time; and less concentrated in the extremes of the cross-section of stocks. Our results are inconsistent with the notion that the momentum phenomenon can be attributed to a priced risk factor or market microstructure effects

TACL - a timeshared hybrid system for control laboratories

A generalized control-system model encompassing a wide variety of systems has been programmed on the analog portion of a hybrid computation system. Five terminals with storage oscilloscopes are con nected to the hybrid computer and are serviced on a round-robin basis. The generalized system can be configured in milliseconds to a specific problem by setting the values of the digital coefficient units and switches of the analog system. A library of specific problems is kept on the system's digital disk. Students use the system by referencing a problem in the library and entering parameter values to define the problem from their terminals. The per-solution time varies with the time scale seZect ed, but averages around a few hundred milliseconds. A user-oriented compiler helps the instructor define new problems to be added. Digital values are assigned by the student to select ed parameters of specific problems, and families of curves representing system performance as a function of control settings may be displayed on the student's terminal. The terminals also display digital data and alphanumerical information.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68305/2/10.1177_003754977502500203.pd

Morphology control in modulated synthesis of metal-organic framework CPO-27

Under embargo until: 2020-08-27The CPO-27/MOF-74 series is among the most investigated metal-organic frameworks because of their usefulness in a diverse range of applications. For specific applications, it will be important to control the shape and size of the particles or crystallites of the material. The modulation approach has been successfully used to direct these parameters in the synthesis of MOFs. Here, we report the synthesis of CPO-27-Ni in the presence of different ratios of benzoic acid and acetic acid as modulators. Yields, powder X-ray diffraction data, scanning electron microscopy results, and elemental, thermogravimetric, and gas sorption analyses are compared to study the influence of the modulator on the product. The results show that we have successfully synthesized pure CPO-27-Ni independent of the amount of modulator. The modulator affects the resulting morphology of the crystalline product with a defined variation of particle sizes and shapes. In addition, ESI-MS has been employed in probing the reaction solutions. It shows the preferred formation of complexes between the metal cation and the modulator, thus indicating that the ligand substitution plays a major role in the crystal growth.acceptedVersio

Competing interactions in the XYZ model

We study the interplay between a XY anisotropy $\gamma$, exchange modulations and an external magnetic field along the z direction in the XYZ chain using bosonization and Lanczos diagonalization techniques. We find an Ising critical line in the space of couplings which occur due to competing relevant perturbations which are present. More general situations are also discussed.Comment: 6 pages, 6 figure

High-power single-frequency operation, at 1064nm and 1061.4nm of a Nd:YAG ring laser end-pumped by a beam-shaped diode bar

A Nd:YAG laser having a ring configuration, with Faraday rotator to provide unidirectional operation has been end-pumped by a single 20 W diode bar equipped with a beam-shaper. A single-frequency TEMoo output of 5.4 W is achieved at 1064 nm. Using a thin intracavity etalon for wavelength selection, a single-frequency output of 4.2 W is obtained on the 1061.4 nm transition

Temperature-induced pair correlations in clusters and nuclei

The pair correlations in mesoscopic systems such as $nm$-size superconducting clusters and nuclei are studied at finite temperature for the canonical ensemble of fermions in model spaces with a fixed particle number: i) a degenerate spherical shell (strong coupling limit), ii) an equidistantly spaced deformed shell (weak coupling limit). It is shown that after the destruction of the pair correlations at T=0 by a strong magnetic field or rapid rotation, heating can bring them back. This phenomenon is a consequence of the fixed number of fermions in the canonical ensemble

Phase diagrams of the generalized spin-1/2 ladder under staggered field and dimerization: A renormalization group study

In the weak-coupling regime of the continuous theories, two sets of one-loop renormalization group equations are derived and solved to disclose the phase diagrams of the antiferromagnetic generalized two-leg spin-1/2 ladder under the effect of (I) a staggered external magnetic field and (II) an explicit dimerization. In model (I), the splitting of the SU(2)$_2$ critical line into U(1) and Z$_2$ critical surfaces is observed; while in model (II), two critical surfaces arising from their underlying critical lines with SU(2)$_2$ and Z$_2$ characteristics merge into an SU(2)$_1$ critical surface on the line where the model attains its highest symmetry.Comment: 10 pages, 9 figure

Z_3 Quantum Criticality in a spin-1/2 chain model

The stability of the magnetization $m=1/3$ plateau phase of the XXZ spin-1/2 Heisenberg chain with competing interactions is investigated upon switching on a staggered transverse magnetic field. Within a bosonization approach, it is shown that the low-energy properties of the model are described by an effective two-dimensional XY model in a three-fold symmetry-breaking field. A phase transition in the three-state Potts universality class is expected separating the $m=1/3$ plateau phase to a phase where the spins are polarized along the staggered magnetic field. The Z$_3$ critical properties of the transition are determined within the bosonization approach.Comment: 5 pages, revised versio