Estimating the abundance and spatial distribution of animal and plant populations is essential for conservation and management. We introduce the R package Distance that implements distance sampling methods to estimate abundance. We describe how users can obtain estimates of abundance (and density) using the package as well documenting the links it provides with other more specialized R packages. We also demonstrate how Distance provides a migration pathway from previous software, thereby allowing us to deliver cutting-edge methods to the users more quickly.
Estimating the abundance and spatial distribution of animal and plant populations is essential for conservation and management. We introduce the R package Distance that implements distance sampling methods to estimate abundance. We describe how users can obtain estimates of abundance (and density) using the package as well as documenting the links it provides with other more specialized R packages. We also demonstrate how Distance provides a migration pathway from previous software, thereby allowing us to deliver cutting-edge methods to the users more quickly.
The complexes [Ag(CH2CI2)(OTeF5)I2 (l), [Ag( 1 ,2-C2H4C12)(OTeF5)12 (2), Ag2(CH2C12)4Pd(OTeF5)4 (3), and Ag2( 1 ,2-C2H4C12)4Pd(OTeF5)4 (4) have been prepared and studied by solution conductimetry, by tensimetric titrations with dichloromethane vapor, and by IR, Raman, liquid and solid 13C NMR, and 35Cl NQR spectroscopy. In addition, the structures of compounds 2,3, and 4 have been determined by single-crystal X-ray diffraction methods: 2, orthorhombic, Pbca, a = 13.371 ( 5 ) A, b = 8.192 (2) A, c = 32.720 (9) A, Z = 4, T = -120 OC, R = 0.052; 3, triclinic, Pi, a = 8.923 (2) A, b = 9.953 (3) A, c = 9.985 (2) A, a = 114.23 (2)O, p = 100.54 (2)", y = 91.42 (2)O, Z = 1, T = -130 OC, R = 0.041; 4, triclinic, Pi, OC, R = 0.025. These compounds provide the first unambiguous evidence that simple chlorinated hydrocarbons can coordinate to metal ions. The Ag-CI distances span the ranges 2.626 (3)-3.000 (3) A (2), 2.775 (2)-2.882 (2) A (3), and 2.645 (1)-2.928 (7) This terminology has been used in many papers. Two recent examples are: (a) Bond, A. M.; Ellis, S. R.; Hollenkamp, A. F. (9) Some of these results have been published in two preliminary reports: (a) Colsman, M. R.; Noirot, M. D.; Miller, M. M.; Anderson, 0. P.; Strauss, S. H. J . Am. Chem. SOC. 1988, 110,6886. (b) Newbound, T. D.; Colsman, M. R.: Miller, M. M.; Wulfsberg, G. P.; Anderson, 0. P.: Strauss, S. H. J . Am. Chem. SOC. 1989, I I I , 3762. (IO) For a recent and comprehensive review see: Kulawiec, R. J.; Crabtree, R. H. Coord. Chem. Reu. Submitted for publication.
The physiological consequences of premature migratory return to freshwater for wild sea-run brown trout (Salmo trutta) smolts infested with sea lice (Lepeophtheirus salmonis) were investigated in the laboratory. Osmoregulatory, metabolic, and stress markers were analysed in order to assess the potential consequences of transfer to freshwater, 19 days after the challenge with L. salmonis. Infestation intensity was significantly reduced following transfer to freshwater, and mortality rates were markedly higher in infested fish maintained in seawater vs. fish that were transferred to freshwater. Significant sea lice effects, consistent across a number of physiological markers, were apparent once L. salmonis developed to the mobile stages. Plasma chloride, lactate, and cortisol all were significantly higher than control values, and liver glycogen concentration was significantly reduced in infested fish in seawater. After return to freshwater, these physiological measures returned to control levels, but significant lice effects persisted for fish maintained in seawater. Premature return of infested sea-run brown trout to freshwater does, therefore, confer significant short-term physiological benefits across a range of osmoregulatory, metabolic, and stress markers.
Through the combination of hydrogen bonding and metal-templated self-assembly, molecular squares and molecular triangles are observed in chloroform solution upon the complexation of hydrogen-bonded dimers of para-pyridyl-substituted 2-ureido-4-[1H]-pyrimidinone (UPy) and an appropriate cis-substituted palladium complex. Molecular modeling studies and NMR analysis confirmed the presence of two distinct structures in solution: the tubular structure of the molecular square and propeller-bowl structure of the molecular triangle.
Direct attachment of two 2-ureido-4-[1H]-pyrimidinone (UPy) subunits to a 3,6-carbazolyl core gives rise to a highly viscous, supramolecular polymer. However, insertion of a methylene spacer between the UPy's and the carbazole leads to a well-defined, cyclic tetramer, in a belt-shaped arrangement, as evidenced by MALDI-TOF, DOSY, and NOESY spectra.
2-Halophenylalkyl-2-oxazolines with alkyl chain spacers of two to six C atoms (n = 0-4) were prepared and their SRN1-type reactions with several base systems examined. The best conditions to promote cyclo-coupling to the corresponding benzocycloalkane derivatives involved use of LDA in THF. The precursors with 3-C-atom and 4-C-atom spacers gave good yields of 2-(1'-phenylindan-1'-yl)-2-oxazolines and 2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR spectroscopy showed the intermediates of the LDA-promoted reactions to be radical anions of the product benzocycloalkanes. This supported an SRN1-type chain mechanism involving initial production of aryl radicals connected to azaenolate ions via the spacer groups. Intramolecular radical to carbanion coupling then generated ring-closed benzocycloalkane radical anions that transferred an electron to more precursor. Diastereoselective radical to carbanion cyclo-coupling reactions were carried out with 2-bromophenylpropyl precursors containing chiral 2-oxazolines. The diastereoselectivity achievable was modest, but the product diastereoisomeric Indane derivatives were easily separable by chromatography.
Intense underwater sounds caused by military sonar, seismic surveys, and pile driving can harm acoustically sensitive marine mammals. Many jurisdictions require such activities to undergo marine mammal impact assessments to guide mitigation. However, the ability to assess impacts in a rigorous, quantitative way is hindered by large knowledge gaps concerning hearing ability, sensitivity, and behavioral responses to noise exposure. We describe a simulation‐based framework, called SAFESIMM (Statistical Algorithms For Estimating the Sonar Influence on Marine Megafauna), that can be used to calculate the numbers of agents (animals) likely to be affected by intense underwater sounds. We illustrate the simulation framework using two species that are likely to be affected by marine renewable energy developments in UK waters: gray seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena). We investigate three sources of uncertainty: How sound energy is perceived by agents with differing hearing abilities; how agents move in response to noise (i.e., the strength and directionality of their evasive movements); and the way in which these responses may interact with longer term constraints on agent movement. The estimate of received sound exposure level (SEL) is influenced most strongly by the weighting function used to account for the specie's presumed hearing ability. Strongly directional movement away from the sound source can cause modest reductions (~5 dB) in SEL over the short term (periods of less than 10 days). Beyond 10 days, the way in which agents respond to noise exposure has little or no effect on SEL, unless their movements are constrained by natural boundaries. Most experimental studies of noise impacts have been short‐term. However, data are needed on long‐term effects because uncertainty about predicted SELs accumulates over time. Synthesis and applications. Simulation frameworks offer a powerful way to explore, understand, and estimate effects of cumulative sound exposure on marine mammals and to quantify associated levels of uncertainty. However, they can often require subjective decisions that have important consequences for management recommendations, and the basis for these decisions must be clearly described.
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