The ontimal finite word leneth (FWL) state-space arithmetical ooeration. The first effect is usuallv measured bv digital system design problem is investigated. Instead of the a global sensitivity measure of the filter function usual sensitivity measure, it is argued that it may be desirable to w,r,t. all the parameters [31-[51, the other by the minimize a frequency weighted sensitivity measure over all similarity transformations. The set of optimal realizations minimiz-noise gain and [' I. ing this weighted sensitivity is completely characterized, and an In [3], a global sensitivity measure of the transfer function algorithm is proposed to find the optimal solution set. It is w.r.t. the parameters of the state-space model was proposed shown that a subset of the optimal realization set consists of by ~~~~~~~~l~ and ~h i~l~. and a reasonable easily sparse Schur realizations, whose actual sensitivity (taking into computable upper bound for this measure was studied. It was account the zero elements) is even smaller than the theoretical minima! ss-xitivity. Some nicr properties of the schur realiza-shown in [51 that the realizations that minimize the upper tiuns are !!iscussed. A numerical exarnule that confirms the bound also minimize the sensitiv~ty measure ~tseif aid that, theoretical results is given.

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Sexually deceptive plants secure pollination by luring specific male insects as pollinators using a combination of olfactory, visual, and morphological mimicry. Flower color is a key component to this attraction, but its chemical and genetic basis remains poorly understood. Chiloglottis trapeziformis is a sexually deceptive orchid which has predominantly dull green-red flowers except for the central black callus projecting from the labellum lamina. The callus mimics the female of the pollinator and the stark color contrast between the black callus and dull green or red lamina is thought to enhance the visibility of the mimic. The goal of this study was to investigate the chemical composition and genetic regulation of temporal and spatial color patterns leading to visual mimicry, by integrating targeted metabolite profiling and transcriptomic analysis. Even at the very young bud stage, high levels of anthocyanins were detected in the dark callus, with peak accumulation by the mature bud stage. In contrast, anthocyanin levels in the lamina peaked as the buds opened and became reddish-green. Coordinated upregulation of multiple genes, including dihydroflavonol reductase and leucoanthocyanidin dioxygenase, and the downregulation of flavonol synthase genes (FLS) in the callus at the very young bud stage underpins the initial high anthocyanin levels. Conversely, within the lamina, upregulated FLS genes promote flavonol glycoside over anthocyanin production, with the downstream upregulation of flavonoid O-methyltransferase genes further contributing to the accumulation of methylated flavonol glycosides, whose levels peaked in the mature bud stage. Finally, the peak anthocyanin content of the reddish-green lamina of the open flower is underpinned by small increases in gene expression levels and/or differential upregulation in the lamina in select anthocyanin genes while FLS patterns showed little change. Differential expression of candidate genes involved in specific transport, vacuolar acidification, and photosynthetic pathways may also assist in maintaining the distinct callus and contrasting lamina color from the earliest bud stage through to the mature flower. Our findings highlight that flower color in this sexually deceptive orchid is achieved by complex tissue-specific coordinated regulation of genes and biochemical pathways across multiple developmental stages.

Orchids are amongst the most diverse of all plant families, and produce a wide array of volatile compounds for pollinator attraction.