An asymptotically minimum bit error rate (BER) linear block precoder is determined for block-by-block communication systems employing linear minimum mean square error (MMSE) equalisation and disjoint detection. The problem is solved by a two-stage optimisation procedure in which a lower bound on the BER is first minimised, and then it is shown how this minimised lower bound can be achieved. Simulation results show that the BER performance of the proposed scheme is superior to the standard MMSE precoder and several other conventional systems such as orthogonal frequency division multiplexing. At reasonable BERs, the signal-to-noise ratio (SNR) gain can be of the order of several decibels.

The Macau economy has recently derailed from the negative-growth sequence established in 1996-1999, and achieved a respectable growth rate of 4.6% in 2 000. In 2001, however, the world economy started to slow and some industrialized economies were even on the brink of recession. Negative expectations have prevailed and additional uncertainty has been heightened by the September 11 events in the USA. As a small open economy, Macau has been inevitably disturbed by the deterioration in external environments. This paper examines all these issues with an ultimate objective to forecast the economic performance of Macau in 2002. It is estimated that Macau’s economy would be able to sustain its positive growth in 2001 and 2002, thanks to effective economic policies and the stimulus from the positive developments in China.

The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-10 (Terrestrial Ecology) team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, gas exchange, oxygen evolution, and biochemical properties of boreal vegetation. This data set describes the spectral optical properties (reflectance and transmittance) of boreal forest conifers and broadleaf tree leaves as measured with a Spectron Engineering SE590 spectroradiometer at the Southern Study Area Old Black Spruce (SSA OBS), Old Jack Pine (OJP), Young Jack Pine (YJP), Old Aspen (OA), Old Aspen Auxiliary (OA-AUX), Young Aspen Auxiliary (YA-AUX), and Young Aspen (YA) sites. The data were collected during the growing seasons of 1994 and 1996 and are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Gaps are unavoidable when compositing small or narrow plant parts (e.g., conifer needles, twigs, narrow leaves, and leaflets) on sample holders in preparation for measuring spectral optical properties. The Daughtry et al. (1989) (A new technique to measure the spectral properties of conifer needles. Remote Sens. Environ. 27:81–91.) method of measuring conifer needle optical properties utilizes a relatively large gap fraction (approximately 0.3–0.6) and needles painted black on one surface of the sample from which the gap fraction of the sample is indirectly determined. Following this protocol typically results in distortions in optical properties, including underestimates in transmittance (sometimes negative values), and only one surface of the sample can be measured. The objectives of this article are to: 1) evaluate the influence of gaps between sample elements (conifer needles, twigs, narrow leaves and leaflets) on optical properties calculated with the published equations from Daughtry et al. (1989) and 2) revise the original Daughtry et al. method for optical property measurements by using an image-analysis to directly measure the gap fraction and use both surfaces of the sample. We achieve these objectives by reviewing the theory and investigating the effects of gaps by measurements of an inert photographic film material, fir needles, and mesquite leaflets. Tests to estimate the transmittance of film samples (film) and foliage (fir needles, mesquite leaflets) indicate that a relatively small gap fraction (less than 0.20) reduces the occurrence of computed negative transmittance values, reduces the variation in computed values, and yields values expected for the “true” or “nongap” transmittance. Employing the image analysis along with reduced gap fractions decreased the variance of measurements and permitted measurements of both surfaces per sample, thus reducing the time required by making half as many samples as originally required by Daughtry et al.

Leaf characteristics, including chlorophyll a content and spectral optical properties, were examined in boreal forest foliage over the growing season during the 1994 BOReal Ecosystem-Atmosphere Study (BOREAS) conducted in Saskatchewan, Canada. We present the results for two deciduous broadleaf species associated with aspen stands: aspen (Populus tremuloides) and hazelnut (Corylus cornata Marsh).

RÉSUMÉLes propriétés spectrales optiques (réflectance, R et absorbtance, A) ont été déterminées à partir de mesures en laboratoire de feuillage, de ramilles et d'écorce de tronc (R seulement) pour des peuplements forestiers boréaux avec des sous-étages arborescents en Saskatchewan (Canada). Ces sites incluent une plantation de pin gris (∼15 ans) (Pinus Banksiana Lamb.) et trois peuplements matures (>60 ans): pin gris, épinette noire (Picea mariana), et peuplier faux-tremble (Populus tremuloidus).Des éléments du couvert supérieur et inférieur de l'étage forestier dominant et des sous-étages ont été étudiés, de juillet à la mi-septembre 1994, dans le cadre du projet BOREAS (Boreal Ecosystem-Atmospheres Study). Dans le cas des conifères, les aiguilles et l'écorce associées à une croissance en 1994 et des périodes variant de deux à cinq années précédentes ont été examinées. Un rapport de bandes (Rapport simple, SR, le rapport proche infrarouge/rouge) et la fraction du rayonnement photosynthétiquement actif absorbé (fAPAR) ont été calculés à partir de spectres des surfaces foliaires adaxiales (au-dessus) et abaxiales (en dessous). On observe des différences significatives pour les paramètres optiques (R, fAPAR, et SR) entre les surfaces foliaires adaxiales et les surface abaxiales, et également au sein des espèces, des peuplements, des strates du couvert et au cours des saisons.Les valeurs les plus élevées de fAPAR et de SR sont associées aux surfaces abaxiales des aiguilles des conifères mais inversement avec les surfaces adaxiales des feuillus. Des relations log-linéaires séparées entre SR et fAPAR sont nécessaires pour les feuillus, le pin et l'épinette noire. Les valeurs R des ramilles et de l'écorce sont similaires à Celles du feuillage à de nombreuses longueurs d'ondes, se dégradant avec la classe d'âge dans la région du proche-infrarouge (PIR). Comparativement à l'épinette noire, les aiguilles de pin gris exhibent: une valeur de réflectance adaxiale inférieure dans le bleu (Rbleu), particulièrement au cours de l'automne; moins de saisonnalité dans les valeurs de réflectance adaxiale qu'abaxiale dans le visible (RVIS); des valeurs plus élevées de réflectance dans le proche-infrarouge (RPIR); et des valeurs plus élevées de fAPAR. Les valeurs de RPIR des aiguilles de pin gris (54 ± 3%) sont de 8–10% plus élevées que pour le feuillage du peuplier faux-tremble ou de l'épinette noire. Des profils verticaux des paramètres optiques foliaires à travers la strate du couvert (3–4 couches) révèlent des patrons nettement différents pour les trois types de communauté (peuplier faux-tremble, épinette, pin gris) pour les valeurs de Rbleu adaxiale, RPIR adaxiale et de SR abaxial. Le seul paramètre optique montrant constamment une dégradation à travers le profil vertical dans tous les couverts est la RPIR abaxiale. Ces résultats devraient fournir des caractérisations optiques utiles pour la paramétrisation des simulations du transfert radiatif en forêt boréale.

RÉSUMÉLes propriétés spectrales optiques (reflectance, RΛ; transmittance, TΛ; et absorption, AΛ) des aiguilles de conifères de deux espèces d'arbres boréales, le pin "jack" (Pinus Banksiana Lamb.) et l'épicéa noir (Picea mariana (Mill.)), ont été sélectionnées en trois sites d'études à Saskatchewan au Canada lors de la campagne Boreal Ecosystem-Atmospheres Study (BOREAS). Des couches de la canopé supérieure ont été suivies durant la saison de croissance s'étalant de mai à septembre 1994. Les sites examinés etaient: un pin "jack" arrivé à maturité (>60 ans), un vieux pin "jack" (OPJ), une récente plantation de pin "jack" (<16 ans), un jeune pin "jack" (YJP), un bosquet d'épicéa noir arrivé à maturité (> 60 ans), et enfin un vieil épicéa noir (OBS). Les couches de la canopé supérieure comportant de jeunes aiguilles (1994) et des deux précédentes générations d'aiguilles (produites en 1992–1993) pour le pin "jack", ainsi que de jeunes aiguilles et des trois à cinq précédentes génération d'aiguilles (produites en 1989–1994) pour l'épicéa noir été ont récoltées pour des mesures en laboratoire. Les propriétés optiques des aiguilles de conifères ont été mesurées en utilisant un nouveau protocole non destructif et plus rapide qui combine les mesures spectrales traditionnelles faites avec un radiomètre/sphère intégrante et une méthode directe d'imagerie pour estimer et corriger la transmittance spectrale pour la fraction de transmittance inter-aiguilles. La méthode permet des mesures à la fois sur les surfaces dorsales (adaxial) et ventrales (abaxial) de tous les échantillons. Le rapport spectral SR (Simple Ratio, le proche infrarouge/rouge) et la fraction de rayonnement photosynthètiquement actif absorbée (fAPAR) ont été calculés sur des spectres adaxiaux et abaxiaux. Des différences significatives de propriétés optiques ont été trouvées pour des aiguilles de différentes classes d'âges, d'espèces et de bosquets au cours de la période de croissance. Le fAPAR (76–86%) était plus faible, et les changements pendant la périodes de croissance plus marquées, avec un pic en milieu d'été, contrairement à ce qui est habituellement supposé pour les forêts à feuillages persistants. Les aiguilles des deux espèces ayant passé un ou plusieurs hivers (classes d'âge 1990–1993) et examinées au printemps, révélèrent une reflectance plus élevée dans le spectre visible (VIS, 400–700 nm), surtout dans les longueurs d'onde du vert, comparée à celle mesurée en été ou en automne. En milieu d'été, des valeurs significativement plus élevées de RΛ et TΛ dans les longueurs d'ondes VIS et/ou proche infrarouge (NIR, 750–1000 nm), et significativement plus faibles de AΛ et fAPAR, ont été observées pour les aiguilles nouvellement poussées en 1994 par rapport aux plus anciennes aiguilles et ce, pour les deux espèces.Comparées à celles du pin "jack", les aiguilles de l'épicéa noir révélèrent une plus grande reflectance adaxiale dans les longeurs d'onde du bleu en particulier en automne; de plus grandes différences saisonnières pour les reflectances VIS et pour les transmittances NIR entre abaxiales et adaxiales; une plus faible reflectance NIR; et un plus faible fAPAR pendant toute la saison. Pour les aiguilles d'épicéa noir plus âgées, l'absorption dans le NIR a augmenté tout au long de la saison de croissance; une relation linéaire (r2 = 0.98) entre l'absorption NIR (par exemple à 800 nm) et la classe d'äge des aiguilles a été manifeste pour l'épicéa noir à la fin de la période de croissance. Des relations linéaires distinctes liant SR à fAPAR (r1 = 0.43–47) ont été établies pour l'épicéa et le pin. Elles ont été calculées à partir de la reflectance spectrale adaxiale pour des pins possédant de plus grands SR quelque soit le niveau de fAPAR. Pour l'épicéa noir, le fAPAR a été plus fortement lié à SR quand les deux paramètres ont été déterminés à partir de la transmittance spectrale (r2 = 0.65). Ces résultats devraient s'avérer extrêmement utiles dans l'interprétation d'observations par avion ou par satellite de la refectance de la canopé, ainsi que pour le paramétrage des simulations de tranfert radiatif pour la télédétection et pour les prévisions de bilan de carbone.

Leaf‐level measurements of gas exchange, chemistry, morphology, and spectral optical properties were acquired at the five instrumented tower sites during the three 1994 growing season intensive field campaigns (IFCs) conducted near Prince Albert, Saskatchewan, as part of the Boreal Ecosystem‐Atmosphere Study (BOREAS). Stands included old and young aspen (OA, YA) associated with the hazelnut shrub, old and young jack pine (OJP, YJP) stands, and an old black spruce (OBS) stand; white spruce (at YA) and an understory herb (dogbane, at OJP) were also examined. Midsummer peak photosynthesis for aspen leaves in the field (A, light saturated) and laboratory ( A max light and CO 2 saturated) was ∼12.6 and 33–41 μmol CO 2 m −2 s −1 . Black spruce exhibited the lowest A, 3 μmol CO 2 m −2 s −1 . Jack pine and black spruce attained their highest A max (17–20 μmol CO 2 m −2 s −1 ) in late summer/early fall. Gas exchange by white spruce was significantly higher and stomatal limitation lower than for other conifers, at levels comparable to broadleaf responses. White spruce foliage had the highest chlorophyll content in fall (∼41 μg cm −2 ), followed by aspen (OA) and hazelnut (YA) in midsummer (∼31 μg cm −2 ). Specific leaf mass of aspen, hazelnut, and conifer foliage was 86, ∼47, and ∼174 g m −2 , respectively. Leaf nitrogen content of broadleaves (18–40 g N g −1 dry wt) was 2–3 times greater than conifer needles (8–12 g N g −1 ). Significantly larger needles were produced at OJP versus YJP, but needle number per age class was greater at YJP. The absorbed photosynthetically active radiation fraction ( f APAR) in June/July averaged ∼80% for broadleaves and ∼83% in conifer needles. The simple ratio (SR, near‐infrared/red ratio) calculated from foliar transmittances was more strongly related to f APAR than SR calculated from reflectances, with stronger correlation for broadleaves ( r =0.92) than for conifers ( r =0.78).

A procedure for determination of conifer needle spectral optical properties (transmittance, T/sub /spl lambda//; reflectance, R/sub /spl lambda//; /spl lambda/=wavelength) was developed to support field measurements acquired in the Boreal Ecosystem-Atmosphere Study (BOREAS). This was a revision of a protocol, C.S. Daughtry et al. (1989), which uses an indirect and labor-intensive step (involving painting of needles) to estimate the inter-needle light transmittance gaps, or gap fraction (GF), in each sample. The present authors procedure uses a direct image capture method to calculate GF, enabling measurements on both dorsal and ventral surfaces of all samples, and is 3-4 times faster than. However, for either method T/sub /spl lambda// underestimates often result, including negative T/sub /spl lambda// in the visible (VIS) spectrum, especially when GF is large (>25%). The authors performed controlled experiments to evaluate the general effect of GF, and errors in GF estimation, on the calculated T/sub /spl lambda// and R/sub /spl lambda// spectra. T/sub /spl lambda// was found to be inversely related to GF, with larger coefficients associated with VIS than near-infrared (NIR) /spl lambda/. Consequently, GF overestimates also yielded T/sub /spl lambda// underestimates. Using these results, they developed a correction algorithm for their BOREAS measurements. "Corrected" estimates of the fraction of absorbed photosynthetically active radiation (APAR) were /spl sim/80-84% for jack pine and 75-78% for black spruce. Correction reduced the Simple Ratio (SR=VIS/NIR) by 40-60% in most cases. SR calculated from corrected T/sub /spl lambda// spectra were significantly higher than those determined from R/sub /spl lambda// spectra.

Oysters (Crassostrea gigas) cultured in Deep Bay, Hong Kong were examined for their bacterial contents from November 1989 to April 1990. Bacterial counts of Faecal coliform, Escherichia coli, Streptococcus faecalis and Salmonellae were high in the adductor muscles, gills, mantle and visceral portions of the Pacific oyster, Crassostrea gigas. It was found that most of the bacteria accumulated in the mantle and visceral portions of the oyster. The maximum number of Faecal coliforms, Escherichia coli, Streptococcus faecalis and Salmonellae were 61.03x10(5), 5.87x10(5), 13.97x10(5) and 21.62x10(5) cells g-1 of wet tissue respectively. Consumption of oysters collected from Deep Bay, if not well-cooked, would be risky and detrimental to health.

In this paper a simple suboptimal dual controller is proposed which brings together Clarke and Gawthrop's (1975) self-tuning controller framework and a generalization of Milito's (Milito el at. 1982) innovations dual controller for a class of linear single-input single-output stochastic systems with unknown parameters. A cost function which includes the variances of both an auxiliary output and its prediction error is used to optimize the system performance. The latter variance term forces the controller to gather information to enhance parameter estimation and thus to indirectly improve control performance. Consequently the dual property inherent in optimal stochastic control is embedded in the structure of the suboptimal controller. Various interpretations and properties of the new algorithm are discussed. Comparative performances of the generalized minimum variance self-tuning controller and the suboptimal dual controller when applied to various simulated stochastic systems are examined. The. improvement of the performance of the new dual controller over self-tuning controllers in terms of transient behaviour and in coping with various time-varying parameter situations is substantial.

The redistribution and electrical characteristics of ion‐implanted S in have been investigated using secondary ion mass spectrometry (SIMS) and Hall profiling in the dose range of . A significant dose dependence of the redistribution has been observed, with the light dose implants exhibiting the most severe diffusion during annealing. In the presence of a sufficiently high level of Si doping, the redistribution of implanted S is reduced for annealing temperatures up to 800°C, possibly due to the formation of a S‐Si complex. Suitably chosen dual implants show a similar effect and result in a higher activation efficiency than is achievable by Si‐only implants of the same total dose. Implantation damage produced by Ar and S dual implants also causes significant redistribution changes. Low levels of damage enhance the S redistribution during annealing, while a high level of damage strongly inhibits it for temperatures up to 900°C. Where the S redistribution is inhibited by damage, however, electrical activity is reduced or lost.

Low dose (5x109-5x1011 cm−2) ion implantations of several ions including C, Be, Mg, and Mn have been performed into high purity epitaxial and bulk InP samples. A comparison of the low temperature (1.7-20 K) photoluminescence spectra of these deliberately doped samples was made to similar spectra of undoped high purity InP grown by LPE, PH3-VPE, and LEC techniques in order to identify the residual acceptors in the undoped samples. Ionization energies obtained for the C, Be, and Mg acceptors (assuming Eg=1.4237 eV) were 44.6 ± 0.3, 41.3 ± 0.3, and 41.0 ± 0.3 megV, respectively. These valu were compared to the ionization energy of the dominant residual acceptor in LPE InP, which also occurs in LEC, polycrystalline, and PH3-VPE material. This acceptor level was first reported in LPE InP by Hesset al. in 1974, who denoted it A1; it has widely been assumed to be C. The value we measure for the ionization energy of A1, which is 41.2 ± 0.3 meV, however, matches that of Mg and Be andnot C. We conclude that C is almost never present as a residual acceptor in undoped InP, and that the residual level in LPE and other material is Mg, or possibly Be. Similar measurements on Si and Sn doped samples showed no evidence of any Si or Sn acceptor level. The Mn acceptor peak was observed to occur at 1.19 eV.

The ionization energies of C, Be, and Mg acceptors in InP have been determined by means of low-temperature (1.7–20 K) photoluminescence measurements on high purity epitaxial and bulk samples which have been implanted with low (5×109–5×1011 cm−2) doses of those impurities. The measured values are 44.6±0.3, 41.3±0.3, and 41.0±0.3 meV, respectively. A comparison with the ionization energies of the residual acceptors in liquid phase epitaxial (LPE), PH3-vapor phase epitaxial, liquid encapsulated Czochralski, and polycrystalline samples indicates that C is almost never present as a residual acceptor in undoped InP. The ionization energy of the main residual acceptor in the LPE samples matches that of both Mg and Be.

Thedata presented here show that Ge- implanted GaAs has a complex amphoteric behavior which is controlled by the implantation dose, implantation temperature, and anneal temperature. Annealing was performed with rf plasma deposited Si3N4 as the encapsulant. Implantations at-100° C resulted in p-layers, while those performed at 100° C and above resulted in n-layers regardless of the dose and anneal temperature. Room temperature implants resulted in p- or n-layers depending on the combination of dose and anneal temperature. Electrical activation and carrier mobilities were low for anneal temperatures ≤ 850°C. Low temperature (6 K) photoluminescence indicated that a significant amount of residual damage remained after annealing. Atomic Ge distribution profiles, carrier con-centration profiles, and junction characteristics of Ge-implanted GaAs planar diodes are also presented.

An electron beam generated by a gas discharge is used to anneal ion implanted silicon. The discharge operating parameters as well as the electron beam energy are measured. Finally, plasma annealing of BF+2 implanted n-type silicon is examined by observing the sheet resistivity of the implanted layers and the resulting diode characteristics.

Synthetic routes have been developed to salts containing the anions [CF 3 PF 5 ] − , [(CF 3 ) 2 PF 4 ] − , [(CF 3 ) 3 PF 3 ] − , [(CF 3 ) 2 AsF 4 ] − , and [(CF 3 ) 3 AsF 3 ] − . These are isolated as stable solids with Cs + , or sometimes Ag + , as the cation. Their 19 F n.m.r. spectra are discussed, and it is suggested that the bis- and tris-(trifluoromethyl)-substituted fluorophosphates have a trans configuration.Trimethyltrifluoromethyltin, (CH 3 ) 3 SnCF 3 , forms 1:1 complexes with PF 5 , (CF 3 ) 2 PF 3 , and (CF 3 ) 3 PF 2 . It is suggested that transfer of a trifluoromethyl group as CF 3 − has occurred here, leading to the formation of trimethyltin derivatives of the trifluoromethyl-substituted fluorophosphates.

International reserves exist in every independent economy that does not completely block cross-border transactions. For the world as a whole and in the developing world in particular, reserves holdings have grown at a markedly fast pace notwithstanding the existence of holding costs and an increasing number of economies to opt for higher exchange-rate flexibility. Meanwhile, some national authorities continue to count on international reserves in enhancing external balance and monetary stability. This paper encompasses an extensive survey of the leading literature, with special focus on policy functions, demand models and indicators of reserve adequacy. By applying the basic framework to Macao, we conclude that the SAR is in a superior position in terms of reserve adequacy by international standards, and highlight important policy implications.