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The longest coherent transmission distance of 0.95km, and highest distance×bandwidth product 19cell hollow-core photonic bandgap fiber (HC-PBGF) are demonstrated, indicating the potential for longer distance HC-PBGF high capacity coherent transmission applications.

We review our fabrication of low loss (50dB/km at 3.3μm) and low bend sensitivity HC-PBGFs for mid-IR operation. Gas sensing applications are highlighted by a high resolution methane spectrum recorded in 1.26m of gas-filled fiber.

A method to track the evolution of a microstructured fibre, from initial preform to final fibre geometry, is presented. Up scaling to longer lengths, new structure development and effects of material parameters can all be explored with this model.

An oligodeoxynucleotide has been synthesized, which mimics an ``antigene'' oligonucleotide with a polypyrimidic stretch on its 5′ side and is protected on its 3′ side against nucelases by a naturally forming and very stable hairpin, 5′GCGAAGC3′. The in vitro degradation of the resulting oligonucleotide d(5′TTCTCGCGAAGC3′) has already been studied by fluorescence resonance energy transfer (FRET) (Refregiers et al. 1996, J Biomol Struct Dyn 14: 365 – 371). The technique required the grafting of fluorophores at both ends of the oligonucleotide. In the present work we have compared the hairpin formed in the presence and in the absence of such fluorophores. This was achieved by the study of the Raman spectra (excitation at 257 nm) of the oligodeoxynucleotides H, which forms the hairpin (5′TTCTCGCGAAGC3′), and a con-trol C (5′TTCTCCGGAAGC3′) which is unable to form the hairpin. Resonance Raman spectroscopy with 257 nm excitation greatly favors the resonance of purines and therefore the study of the 3′ part of the oligonucleotides. The difference spectrum obtained from resonance Raman spectra of C and H showed marker peaks specific for hairpin formation. The search for these marker peaks in difference spectra involving the Raman spectrum of H labeled by fluorophores and either C or H proved that the fluorophores do not modify the structure of the hairpin but only the vibrations of the two terminal bases on which the fluorophores are grafted. The use of such labeling is then justified in order to allow oligonucleotides protected by a hairpin on their 3′ side to be studied by fluorescence spectroscopy.

Resonance Raman spectra excited at 257 nm are reported for the complexes of the Nickel, Cobalt and Zinc derivatives of Tetrakis(4-N-methylpyridyl)porphine with poly(dA.dT)2, poly(dA)poly(dT), poly(dG.dC)2 and poly(dG).poly(dC). These spectra are interpreted as evidence of multiple outside binding modes with poly(dA).poly(dT), and of evidence for an outside binding mode with Poly(dG.dC)2. Some results obtained for the zinc derivative with poly(dA).poly(dT) suggest a binding mode peculiar to this derivative.

Hollow-Core Photonic-Bandgap Fibres (HC-PBGFs) offer several distinct advantages over conventional fibres, such as low latency and radiation hardness; properties that make HC-PBGFs interesting for the high energy physics community. This contribution presents the results from a gamma irradiation test carried out using a new type of HC-PBGF that combines sufficiently low attenuation over distances that are compatible with high energy physics applications together with a transmission bandwidth that covers the 1550nm region. The radiation induced attenuation of the HC-PBGF was two orders of magnitude lower than that of a conventional fibre during a 67.5 hour exposure to gamma-rays, resulting in a radiation-induced attenuation of only 2.1dB/km at an accumulated dose of 940kGy.

The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fiber's low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008nm over 290m of 19 cell HC-PBGF is reported.

We examine mid- to late Holocene centennial-scale climate variability in Ireland using proxy data from peatlands, lakes and a speleothem. A high degree of between-record variability is apparent in the proxy data and significant chronological uncertainties are present. However, tephra layers provide a robust tool for correlation and improve the chronological precision of the records. Although we can find no statistically significant coherence in the dataset as a whole, a selection of high-quality peatland water table reconstructions co-vary more than would be expected by chance alone. A locally weighted regression model with bootstrapping can be used to construct a ‘best-estimate’ palaeoclimatic reconstruction from these datasets. Visual comparison and cross-wavelet analysis of peatland water table compilations from Ireland and Northern Britain shows that there are some periods of coherence between these records. Some terrestrial palaeoclimatic changes in Ireland appear to coincide with changes in the North Atlantic thermohaline circulation and solar activity. However, these relationships are inconsistent and may be obscured by chronological uncertainties. We conclude by suggesting an agenda for future Holocene climate research in Ireland.

International audience; Gas-filled hollow optical fiber references based on the P(13) transition of the ν1+ν3 band of C122H2 promise portability with moderate accuracy and stability. Previous realizations are corrected (

We formulate a simple model based on mass conservation to accurately predict the structural parameters of hollow-core photonic bandgap fibers from knowledge of the second stage preforms from which they are drawn. We show that combining this model with precalculated property maps can allow real-time prediction of the optical properties of manufactured fibers.

We report fabrication of the first low-loss, broadband 37-cell photonic bandgap fiber. Exploiting absence of surface modes and low cross-talk in the fiber we demonstrate mode division multiplexing over three modes with record transmission capacity.

Hollow core-photonic bandgap fiber, operating in the spectral region between 3 and 4 µm, is reported. Order of magnitude loss reduction is demonstrated (0.13dB/m) compared to previously reported fibers, combined with very low bend sensitivity.

We review our recent progress in the fabrication, characterization, modeling and splicing of wide transmission bandwidth hollow core photonic bandgap fibers and discuss their modal properties and potential for data transmission.

We review our recent progress in the fabrication, characterization, modeling and splicing of wide transmission bandwidth hollow core photonic bandgap fibers and discuss their modal properties and potential for data transmission.

Photonic bandgap fibers (PBGF) potentially offer a very substantial increase of capacity per fiber over solid core fibers. We review transmission experiments using PBGF and their viability for next-generation transmissions systems.

Validation of novel splicing strategy enabling integration of hollow-core photonic band gap fiber with both itself and conventional SMF is presented. Self-splices are robust and low loss (0.16dB). Penalty-free 40Gbit/s data transmission is demonstrated in 1km arrangement of spliced HC-PBGF.

Summary Interactions of the antiretroviral hypericin molecule with polynucleotides, i.e. poly(dG-dC), poly(dA-dT), poly(rG) and poly(rC), have been studied in aqueous solutions by resonance Raman spectroscopy, using an UV excitation wavelength which induces a specific resonance enhancement of spectral band intensities corresponding to proper nucleic base modes of vibration. It is shown that : i) hypericin selectively interacts with the N7 sites of purines, ii) the strength of interaction depends on the polymer structure, and : iii) interaction with guanine is stronger than with adenine molecules.

Comparison of pre-conquest and contemporary Andean llama and alpaca phenotypes suggests that a breakdown in specialized breeding took place after European contact which led to the disappearance of fine fibre producing alpaca and llama breeds. The causes of this loss ultimately lie in the decimation of native Andean herds and herders during the Spanish conquest. The heterogeneous characteristics of today's animals can be attributed to extensive hybridization and a possible genetic bottle neck during the 16th century.

Actualmente es posible determinar el estatus de especies silvestres mediante el analisis de ADN extraido de muestras no invasivas como las heces. Aunque dichos analisis suelen ser dificultosos debido principalmente a la composicion y conservacion de las heces, se ha demostrado en muchas especies que con el desarrollo de metodos adecuados de extraccion es posible maximizar la fiabilidad y eficacia de este procedimiento. Por tanto, el objetivo del presente estudio fue optimizar un metodo de extraccion de ADN de heces de vicuna Vicugna vicugna mensalis, especie clasificada como casi amenazada en el Peru, con la finalidad de obtener ADN de suficiente calidad para analisis moleculares. Se recolectaron 51 muestras de heces durante los meses de agosto y septiembre de 2008 en dos comunidades vicuneras ubicadas a mas de 4600 msnm en los departamentos de Junin y Moquegua. Luego de observar la defecacion, las muestras fueron recolectadas en forma inmediata, conservadas en etanol y transportadas al laboratorio para la extraccion del ADN. El kit comercial QIAamp® DNA Stool Mini Kit (QIAGEN) fue modificado para incluir un vigoroso y extenso proceso de agitacion y los resultados fueron comparados con dos protocolos comunmente utilizados: fenol/cloroformo/alcohol isoamilico y el mismo kit QIAGEN. La cantidad del ADN extraido fue observado en electroforesis horizontal en geles de agarosa, y la calidad evaluada mediante la amplificacion y visualizacion de los tamanos esperados de los microsatelites YWLL46 y LCA19. Aunque se logro extraer ADN con los tres metodos, solamente el metodo modificado permitio obtener ADN de suficiente calidad para ser utilizado en pruebas moleculares. Palabras clave: extraccion de ADN, heces, vicuna

Se reporta el desarrollo y optimizaciones de tecnicas moleculares (PCR simple, mul- tiple y semi-anidada) para determinar el sexo de camelidos sudamericanos (CSA) amplifi- cando la secuencia del gen Zinc Finger Protein (ZF). La tecnica utilizo ADN obtenido de 28 muestras de sangre de alpacas, llamas y vicunas, 20 muestras de heces de vicunas y guanacos conservadas en etanol al 96%, y 22 embriones de alpaca colectados entre 72 y 96 horas postmonta y preservados en etanol. Las muestras de ADN de sangre y heces fueron extraidas usando kits comerciales, y las de embriones aplicando tres metodos (ebullicion, proteinasa K y fenol-cloroformo). Una vez optimizada la PCR simple para la deteccion de los genes ZFY y ZFX, se implemento la PCR multiple para ADN de sangre y heces y la PCR semi-anidada para ADN de embriones. La tecnica de PCR multiple deter- mino el sexo correctamente en el 100% de las muestras de ADN sanguineo, en el 87.5% de muestras de ADN de heces colectadas en 2008 y en el 50% de las muestras de ADN de heces colectadas en 2004 y preservadas durante cuatro anos antes del analisis. La prue- ba de PCR semi-anidada, sin embargo, no pudo ser optimizada

International audience; This paper describes the development and evaluation of compact and simple acetylene-stabilized diode laser frequency standards in the 1.55 μm spectral region. A variety of spectroscopic configurations have been investigated, using bulk acetylene cells and an acetylene-filled hollow core photonic crystal fiber. Frequency stability and reproducibility data, obtained by heterodyne beat frequency comparison with cavity-enhanced standards, will be presented for sources including a distributed feedback diode laser and a digital supermode distributed Bragg reflector diode laser.

We report on progress in different hollow core photonic crystal fiber (HC-PCF) design and fabrication for atomic vapor based applications. We have fabricated a Photonic bandgap (PBG) guiding HC-PCF with a record loss of 107dB/km at 785nm in this class of fiber. A double photonic bandgap (DPBG) guiding HC-PCF with guidance bands centred at 780nm and 1064nm is reported. A 7-cell 3-ring Kagome HC-PCF with hypocycloid core is reported, the optical loss at 780nm has been reduced to 70dB/km which to the best of our knowledge is the lowest optical loss reported at this wavelength using HC-PCF. Details on experimental loading of alkali metal vapours using a far off red detuned laser are reported. This optical loading has been shown to decrease the necessary loading time for Rb into the hollow core of a fiber. The quantity of Rb within the fiber core has been enhanced by a maximum of 14% through this loading procedure.

We report transmission of 37 x 40 Gbit/s C-band channels over 250 m of hollow core band gap fibre, at 99.7% the speed of light in vacuum. BER penalty below 1 dB as compared to back-to-back was measured across the C-band.

We study the rich multimode content of an ultra-low loss hollow core photonic bandgap fiber using two complementary techniques which allow us to investigate both short and long propagation distances. Several distinct vector modes are clearly identified, with evidence of low intermodal coupling and distributed scattering.

The first demonstration of a hollow core photonic bandgap fiber suitable for high-rate data transmission at 2µm is presented. Using a custom built Thulium doped fiber amplifier, error-free 8Gbit/s transmission in an optically amplified data channel at 2008nm is reported for the first time.

We discuss the potential advantages that hollow core photonic bandgap fibers may ultimately have over conventional all solid fibers and review the state-of-the-art, fundamental physical limits and the many technological challenges to be overcome.

19-cell defect HC-PBGF is fabricated with record low loss (5.2 dB/km) at 2 μm. Gas absorption lines present in the fiber post-fabrication are quantified with initial conclusions on the origin and removal of relevant species.

A photonic microcell (PMC) is a length of gas-filled hollow core-photonic crystal fiber (HC-PCF) which is hermetically sealed at both ends by splicing to standard single mode fiber. We describe advances in the fabrication technique of PMCs which enable large core Kagome-lattice HC-PCFs to be integrated into PMC form. The modified fabrication technique uses fiber-tapering to accommodate the large dimensions of the fiber and enables low loss splices with single mode fiber by reducing mode field mismatch. Splice losses as low as 0.6 dB are achieved between 1-cell defect Kagome HC-PCF and single mode fiber. Relative to the previously reported PMCs, which were based on photonic bandgap HC-PCF, the present Kagome HC-PCF based PMC provides broad optical transmission, surface mode-free guidance and larger core at the cost of slightly increased fiber attenuation (~0.2 dB/m). Therefore, the integration of this fiber into PMC form opens up new applications for PMC-based devices. The advantage of the large core dimensions and surface mode free guidance for quantum optics in gas-filled HC-PCF are demonstrated by generation of narrow sub-Doppler features in an acetylenefilled large core PMC.

International audience; We demonstrate for the first time an optically pumped gas laser based on population inversion using a hollow core photonic crystal fiber (HC-PCF). The HC-PCF filled with 12C2H2 gas is pumped with ~5 ns pulses at 1.52 μm and lases at 3.12 μm and 3.16 μm in the mid-infrared spectral region. The maximum measured laser pulse energy of ~6 nJ was obtained at a gas pressure of 7 torr with a fiber with 20 dB/m loss near the lasing wavelengths. While the measured slope efficiencies of this prototype did not exceed a few percent due mainly to linear losses of the fiber at the laser wavelengths, 25% slope efficiency and pulse energies of a few mJ are the predicted limits of this laser. Simulations of the laser’s behavior agree qualitatively with experimental observations.

A continuous-wave diode laser is stabilized to a near-infrared acetylene transition inside a sealed kagome photonic crystal fiber. Stability and absolute frequency are measured with a frequency comb, and polarization sensitivity is observed.

Alpha-track detectors made of CR-39 plastic were successfully tested in monitoring surface alpha contamination in decontamination and decommissioning. The alpha registration efficiency was about 70%. At 3.7 Bq cm -2 a 10:1 signal-to-noise response was obtained after a 100-min exposure. The alpha-track detector maps small-scale spacial variability of alpha contamination that conventional survey meters cannot. The detector recognizes hot particles. Small-sized detectors are deployable in difficult-to-access locations such as cracks or under tightly fitting equipment where dirt resists easy removal

A CW fiber laser is stabilized to near-infrared transitions of 12C2H2 inside kagome fibers and characterized with a frequency comb. ±10 kHz accuracy is achieved, and performance in sealed photonics microcells is explored.

We report on a novel means which lifts the restriction of the limited optical bandwidth of photonic bandgap hollow-core photonic crystal fiber on generating high order stimulated Raman scattering in gaseous media. This is based on H(2)-filled tapered HC-PCF in which the taper slope is matched with the effective length of Raman process. Raman orders outside the input-bandwidth of the HC-PCF are observed with more than 80% quantum-conversion using a compact, low-power 1064 nm microchip laser. The technique opens prospects for efficient sources in spectral regions that are poorly covered by currently existing lasers such as mid-IR.

We report on kagomé-lattice photonic microcells with low losses, large outer diameters, and large cores. The large (40-70microm) cores are accommodated by tapering the fibers and splicing the reduced ends to a single-mode fiber. We demonstrate the repeatability of this process and obtain splice losses of 0.6dB by optimizing the taper transition length. Narrow electromagnetically induced transparencies and saturable absorption are demonstrated in an acetylene-filled photonic microcell.

We demonstrate what we believe is the first hollow fiber gas laser based on population inversion. A single-cell-defect Kagome fiber with a core diameter of about 40 microns was filled with a few torr of acetylene (12C 2 H 2 ). Acetylene has absorption transitions in the attractive telecommunication C band region and recently lasing was observed at about 3 microns from a gas cell when optically pumped. Pumping the gas filled fiber (1.65 m) with micro Joule pulses from a 5-ns OPO resulted in the emission of two laser lines at 3123.2 nm and 3162.4 nm. The pump (-1521 nm) was in the guiding regions of the fiber (loss ∼ 0.75 dB/m) while the laser output occurred in weakly guided modes (∼ 20 dB/m). This laser combines attractive features of both fiber and gas lasers, such as the confinement of the pump and laser over long interaction lengths in a compact configuration, the many possible emission wavelengths of various gases, high damage threshold, and the potential for coherent beam combining of mutually incoherent pump sources. While this first laser demonstration used a pulsed pump, the gas filled fiber laser is particularly attractive for pumping with CW laser sources.

Lasing from population inversion in the mid-IR (3.1-3.2 m) region was observed from a gas (acetylene) filled hollow core photonic crystal fiber when optically pumped at 1.5 m.

We have developed an all-fiber system which we use to demonstrate slow and fast light based on electromagnetically induced transparency in a 20 meter acetylene-filled photonic microcell. Using this system, 30 ns pulses of probe light were delayed and advanced by up to 5 ns and 1 ns respectively. The delay/advance is tunable through the probe detuning and the coupling Rabi frequency. Through optimization of experimental parameters such as acetylene pressure, coupling laser power and decoherence rates it is shown that a pulse delay of 30 ns/m is possible. Limitations imposed on the fiber length by resonance group velocity dispersion and spectral reshaping are also discussed. In addition to optical buffering, we suggest a slow-light based fiber optical gyroscope with an enhanced signal-to-noise ratio of ~ 92.

A CW fiber laser is stabilized to the P(13) ν1+ν3 transition of 12C2H2 inside large-core kagome fiber using FM spectroscopy techniques and characterized with a frequency comb. Improved line widths are explored.

We fabricated low insertion loss and large core (40 – 70 µm) kagome lattice acetylene-filled photonic microcells by tapering the large outer diameter kagome fibers and splicing their reduced ends to a single mode fiber.

Ultra-high reflectivity is achieved at the end-face of a hollow-core PCF via the insertion and fusion of a metal-coated tapered single-mode-fiber to the core of the hollow fiber. Saturable absorption is demonstrated using this device.

The spatial mode evolution of spectral Raman components generated in and propagated through a tapered hollow-core PCF reveals adiabatic transition from core modes to surface modes. Its effect on the Raman converter is discussed.

We report on the design, fabrication and characterization of hollow-core photonic crystal fiber with two robust bandgaps that bridge the benchmark laser wavelengths 1064 nm with 1550 nm, and 1064 nm with 780 nm.

Electromagnetically induced transparencies are recorded in a 20 metre acetylene-filled photonic microcell and used to observe pulses of probe light delayed (advanced) by up to 5 ns (1 ns). Suggested applications include interferometry.

Guanacos (Lama guanicoe) are the most important native herbivorous species in the South American steppes and the dominant ungulate in a fauna rich in rodents but poor in large mammal species. Between 2 and 4 subspecies are usually recognized within Lama guanicoe, based on subtle morphological differences and geographic distribution. To evaluate whether molecular variation is consistent with the latter hypotheses, we analyzed the complete cytochrome-b and partial control region mitochondrial DNA sequences of L. guanicoe from 22 localities in Peru, Bolivia, Argentina, and Chile. Sequence analyses of both genes support the monophyly of the species but failed to distinguish the occurrence of subspecies along the geographic range. Despite that, the northernmost populations (Peru and northern Chile) showed some degree of genetic differentiation with respect to southern representatives from Argentina, Bolivia, and rest of Chile. Analysis of genetic diversity also showed a strong signal of past low population size and a recent population expansion.

We present a fast implementation of the spatial and spectral imaging ( $\text{S}^{2})$ technique for a modal analysis of multimode optical fibers. It utilizes a continuously scanning tunable laser source with an InGaAs camera operating at 500 Hz along with inline data processing to increase the measurement repetition rate, by reducing the run up/run down time between two successive scans (about 27 times faster as compared with the previous state of the art). This allows real-time mode content monitoring of a multimode fiber. We illustrate the potential of this tool by collecting an 110 000 wavelength $\text{S}^{2}$ spectrogram of a five mode-group fiber in minutes, and tracking, in real-time, the four LP11 modes of the same fiber as the launch polarization is rotated.

Tobago and Trinidad are two Caribbean islands with distinct genetic background and lifestyles; while Tobago is serene and a tourist centre, Trinidad is characterized by a hustling and bustling lifestyle. The study was aimed at determining and comparing the prevalence of the metabolic syndrome (MetS) and its critical components in type 2 diabetic patients using the new International Diabetes Federation (IDF) definition.Four hundred and thirteen (166 Tobago, 247 Trinidad) type 2 diabetic patients visiting 10 lifestyle disease clinics were studied. Blood pressure, anthropometric parameters (height, weight, body mass index and waist circumference) and overnight fasting blood samples were taken. Plasma glucose and serum triglycerides, total cholesterol, LDL- and HDL-cholesterol, insulin, and adiponectin were determined. Insulin resistance (IR) was determined using the HOMA method.The patients in Tobago were significantly older than patients in Trinidad (p0.001) but the duration of diabetes (9.4 +/- 0.5 vs. 11.1 +/- 0.7 yr), medications, generalized (31.7 vs. 38.8%) and central (78.5 vs. 83.7%) obesity were similar (p0.05). In comparison with patients in Tobago, diabetic patients in Trinidad, irrespective of gender, had significantly higher prevalence of IDF critical components such as raised BP, raised triglycerides and reduced HDL-cholesterol (all, p0.001). Thus, while more patients in Trinidad were diagnosed with MetS based on three or four components, more patients in Tobago were diagnosed based on two components (p0.001).There were high prevalence rates of the components of the MetS in both the islands of Tobago and Trinidad. Quantitatively, the aggregation of the components is higher in patients in Trinidad, which constitute greater risk for adverse cardiovascular outcome. Controlling central obesity should be the target in preventing MetS in the two islands.

Four camelid species exist in South America: two wild, the guanaco (Lama guanicoe) and the vicuna (Vicugna vicugna), and two domestic, the alpaca (Lama pacos) and the llama (Lama glama). However, the origin of the domestic species has been a matter of debate. In the present study, variations in chromosome G banding patterns and in two mitochondrial gene sequences have been used to study the origin and classification of the llama and alpaca.-Similar patterns in chromosome G band structure were observed in all four Lamini species, and these in turn were similar to the bands described for camels, Camelus bactrianus. However, fine and consistent differences were found in the short arms of chromosome 1, separating camels, guanacos and llamas from vicunas and alpacas. This pattern was consistent even in a hybrid guanaco x alpaca. Equivalent relationship showed the complete cytochrome b gene sequences, and the minimum expansion tree of the partial control region sequence, grouping guanaco with llama and vicuna with alpaca. Phylogenetic analyses showed V. vicugna and L. guanicoe as monophyletic groups. Analysis of both gene sequences revealed two clades within vicuna, concordant with the two described subspecies, but the results for guanaco did not confirm existence of the four previously proposed subspecies. The combined analysis of chromosomal and molecular variation showed close genetic similarity between alpacas and vicunas, as well as between llamas and guanacos. Although directional hybridization was revealed, our results strongly support the hypothesis that the llama would have derived from L. guanicoe and the alpaca from V. vicugna, supporting reciassification as V. pacos.

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275,000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22 degrees S) dry Andes 14-12,000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29 degrees S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts.

We present a novel method to validate the relative amount of power carried by high order modes in a multimode fiber using a Spatial and Spectral (S(2)) imaging technique. The method can be utilized to calibrate the S(2) set-up and uses Fresnel reflections from a thin glass plate to compare theoretical values with experimental results. We have found that, in the most general case, spectral leakage and sampling errors can lead S(2) to underestimate the multipath interference (MPI) of high order modes by several decibels, thus significantly impairing the result of the measurement. On the other hand, by applying suitable corrections as described in this work, we demonstrate that the S(2) produces MPI estimates that are accurate to within 1dB or better.