Online Bin Packing with Advice

We consider the online bin packing problem under the advice complexity model where the 'online constraint' is relaxed and an algorithm receives partial information about the future requests. We provide tight upper and lower bounds for the amount of advice an algorithm needs to achieve an optimal packing. We also introduce an algorithm that, when provided with log n + o(log n) bits of advice, achieves a competitive ratio of 3/2 for the general problem. This algorithm is simple and is expected to find real-world applications. We introduce another algorithm that receives 2n + o(n) bits of advice and achieves a competitive ratio of 4/3 + {\epsilon}. Finally, we provide a lower bound argument that implies that advice of linear size is required for an algorithm to achieve a competitive ratio better than 9/8.Comment: 19 pages, 1 figure (2 subfigures

On the List Update Problem with Advice

We study the online list update problem under the advice model of computation. Under this model, an online algorithm receives partial information about the unknown parts of the input in the form of some bits of advice generated by a benevolent offline oracle. We show that advice of linear size is required and sufficient for a deterministic algorithm to achieve an optimal solution or even a competitive ratio better than $15/14$. On the other hand, we show that surprisingly two bits of advice are sufficient to break the lower bound of $2$ on the competitive ratio of deterministic online algorithms and achieve a deterministic algorithm with a competitive ratio of $5/3$. In this upper-bound argument, the bits of advice determine the algorithm with smaller cost among three classical online algorithms, TIMESTAMP and two members of the MTF2 family of algorithms. We also show that MTF2 algorithms are $2.5$-competitive

PREFERENCIA DE OVINOS Y BOVINOS POR FRUTOS DE SEIS ESPECIES ARBÓREAS

The preference of sheep and cattle for fruits from Acacia cochliacantha Humb. & Bonpl. Willd., Caesalpinia cacalaco Bonpl., Vachellia pennatula (Schltdl. & Cham.) Benth., Chloroleucon mangense (Jacq.) Britton & Rose, Senna atomaria (L.) H.S. Irwin & Barneby, and Guazuma ulmifolia Lam, was determined. During the first trial, the preference of Tropical-Tarantés milking Criollo calves was determined, and in the second and third, the preference of Pelibuey sheep. In each trial, crushed fruits were offered simultaneously in periods of 15 minutes, for seven consecutive days, using a cafeteria arrangement. The fruits used showed more than 8 % of raw protein (RP), with C. mangense standing out (20.7 %), while the highest in vitro digestibility of the dry matter (INDDM) was for C. cacalaco (69.9 %); the presence of tannins, terpenes, saponins and flavonoids was recorded in fruits, with A. cochliacantha standing out with the highest content. The cattle preferred (P<0.001) V. pennatula (252±73) and G. ulmifolia (247±54 g animal-1) over other fruits. The non-fasting sheep showed greater preference for C. mangense (79±35 g animal-1 day-1), while the fasting sheep preferred (P<0.001) C. mangense, A. pennatula and A. cochliacantha (76±28, 73±9 y 60±12 g animal-1 day-1, respectively). Bothe the cattle and the sheep showed preference for one fruit, although those of highest preference were C. mangense for sheep, A. pennatula and G. ulmifolia for cattle, and the C. cacalaco fruits were the least accepted.Se determinó la preferencia de ovinos y bovinos hacia frutos de Acacia cochliacantha Humb. & Bonpl. Willd., Caesalpinia cacalaco Bonpl., Vachellia pennatula (Schltdl. & Cham.) Benth., Chloroleucon mangense (Jacq.) Britton & Rose, Senna atomaria (L.) H.S. Irwin & Barneby y Guazuma ulmifolia Lam. En la primera prueba se determinó la preferencia de becerros criollo lechero Tropical-Tarantés y en la segunda y tercera, la preferencia de ovinos pelibuey. En cada prueba se ofrecieron simultáneamente frutos molidos en periodos de 15 minutos, durante siete días consecutivos, utilizando un arreglo de cafetería. Los frutos utilizados registraron más de 8% de proteína cruda (PC) destacando C. mangense (20.7%), mientras que la digestibilidad in vitro de la materia seca (DIVMS) más alta fue para C. cacalaco (69.9%); se registró presencia de taninos, terpenos, saponinas y flavonoides en los frutos, sobresaliendo A. cochliacantha con mayor contenido. Los bovinos prefirieron (P<0.001) V. pennatula (252±73) y G. ulmifolia (247±54 g animal-1) sobre otros frutos. Los ovinos sin ayuno mostraron mayor preferencia por C. mangense (79±35 g animal-1 día-1) mientras que los ovinos con ayuno prefirieron (P<0.001) C. mangense, A. pennatula y A. cochliacantha (76±28, 73±9 y 60±12 g animal-1 dia-1, respectivamente). Tanto los bovinos y ovinos mostraron preferencia por algún fruto, sin embargo de mayor preferencia fueron C. mangense para ovinos, A. pennatula, y G. ulmifolia para bovinos, y los frutos de C. cacalaco fueron los menos aceptados

Revisiting the Problem of Searching on a Line

We revisit the problem of searching for a target at an unknown location on a line when given upper and lower bounds on the distance D that separates the initial position of the searcher from the target. Prior to this work, only asymptotic bounds were known for the optimal competitive ratio achievable by any search strategy in the worst case. We present the first tight bounds on the exact optimal competitive ratio achievable, parameterized in terms of the given bounds on D, along with an optimal search strategy that achieves this competitive ratio. We prove that this optimal strategy is unique. We characterize the conditions under which an optimal strategy can be computed exactly and, when it cannot, we explain how numerical methods can be used efficiently. In addition, we answer several related open questions, including the maximal reach problem, and we discuss how to generalize these results to m rays, for any m >= 2

Distribución y composición de la materia orgánica en sedimentos de la zona de oxígeno mínimo del Pacífico nororiental mexicano: implicaciones paleoceanográficas

Total organic carbon (TOC) content, total nitrogen (TN) content, elemental (C and N), and isotopic (d13C-TOC) composition of organic matter derived from both marine and terrestrial sources constrain the relative contributions from marine productivity, the mangroves, and the continental wind erosion of 36 carbonate-free surface sediments along the southwestern coast of the Baja California Peninsula. In general, the spatial patterns of TOC, TN, C:N ratio and d13C-TOC are similar. The maximum content of TOC (14.5%) and TN (1.6%) were measured inside the oxygen minimum zone (OMZ). The stable carbon isotopic compositions were enriched in 12C in surface sediments at suboxic sites within the OMZ. The C:N ratio and δ13C-TOC values indicated that the organic sediment material is predominantly of marine origin, with a minor contribution from the terrestrial source or mangroves. In the stations near to the coast, the high values of the C:N ratio and the depleted 13C values suggest a proportionally greater accumulation of terrestrial organic matter. The terrestrial-derived organic carbon content is <10% at the continental margin and >40% at the stations near to the coast, based on a Mixing Model of End Members.El contenido de carbono orgánico total (COT), nitrógeno total (NT), la composición elemental (C y N) e isotópica derivada de fuentes marina y terrestre ha permitido delimitar la contribución relativa de la productividad marina, los manglares y la erosión continental (eólicos) de 36 muestras de sedimentos superficiales (libres de carbono inorgánico) en el margen SW de Baja California. En general, la distribución espacial de COT, NT, la razón C:N y el d13C-COT son similares. El contenido máximo de COT (14.5%) y NT (1.6%) fue observado dentro de la zona de oxígeno mínimo. La composición isotópica de carbono está enriquecida en 12C en sedimentos superficiales de sitios subóxicos dentro de la ZOM. La razón C:N y los valores del d13C-COT indicaron que el material orgánico en sedimentos es predominantemente de origen marino con una menor contribución terrestre o de manglar. En las estaciones cercanas a la costa, los mayores valores de la razón C:N y los valores empobrecidos en 13C sugieren una acumulación mayor de materia orgánica terrestre. El contenido de carbono orgánico derivado de origen terrestre es <10% en el margen continental y >40% en estaciones cercanas a la costa sobre la base del modelo de mezcla de “end-members”

APHIDIDAE (HEMIPTERA) DE ROSA SP, PROCEDENTES DE LIMA-PERÚ

Se reportan las siguientes especies colectadas sobre ejemplares de Rosa sp provenientes de la Provincia de Lima: Macrosiphum rosae (Linnaeus), Myzus persicae (Sulzer), Rhodobium porosum y Wahlgreniella nervata (Gillette). En ésta oportunidad no se encontró a Myzaphis rosarum (Kaltenbach), comúnmente conocida como el áfido menor de las rosas

Pressure-Induced Phase-Transition Sequence In Cof 2 : An Experimental And First-Principles Study On The Crystal, Vibrational, And Electronic Properties

We report a complete structural study of CoF2 under pressure. Its crystal structure and vibrational and electronic properties have been studied both theoretically and experimentally using first-principles density functional theory (DFT) methods, x-ray diffraction, x-ray absorption at Co K-edge experiments, Raman spectroscopy, and optical absorption in the 0–80 GPa range. We have determined the structural phase-transition sequence in CoF2 and corresponding transition pressures. The results are similar to other transition-metal difluorides such as FeF2 but different to ZnF2 and MgF2, despite that the Co2+ size (ionic radius) is similar to Zn2+ and Mg2+. We found that the complete phase-transition sequence is tetragonal rutile (P42/mnm) → CaCl2 type (orthorhombic Pnnm) → distorted PdF2 (orthorhombic Pbca)+PdF2 (cubic Pa3¯) in coexistence → fluorite (cubic Fm3¯m) → cotunnite (orthorhombic Pnma). It was observed that the structural phase transition to the fluorite at 15 GPa involves a drastic change of coordination from sixfold octahedral to eightfold cubic with important modifications in the vibrational and electronic properties. We show that the stabilization of this high-pressure cubic phase is possible under nonhydrostatic conditions since ideal hydrostaticity would stabilize the distorted-fluorite structure (tetragonal I4/mmm) instead. Although the first rutile → CaCl2-type second-order phase transition is subtle by Raman spectroscopy, it was possible to define it through the broadening of the Eg Raman mode which is split in the CaCl2-type phase. First-principles DFT calculations are in fair agreement with the experimental Raman mode frequencies, thus providing an accurate description for all vibrational modes and elastic properties of CoF2 as a function of pressure

Transition period between vegetation growth and senescence controls interannual variability of C fluxes in a Mediterranean reed wetland

Wetlands are crucial ecosystems modulating climate change due to their great potential to capture carbon dioxide (CO2), emit methane (CH4) and regulate local climate through evapotranspiration (ET). Common reed wetlands are particularly interesting given their high productivity, abundance and highly efficient internal gas-transport mechanism. However, little is known about the interannual behavior and dominant controlling factors of Mediterranean reed wetlands, characterized by seasonal flooding and remarkable weather variability. After 6 years of ecosystem carbon and ET flux measurements by eddy covariance (3 years for CH4 fluxes), this study shows the functional vulnerability of such wetlands to climate variability, switching between carbon (CO2+CH4) sink (660 g CO2-eeq m-2 y -1 , in 2014) and source (360 g CO2-eq m-2 y -1 , in 2016) in short periods of time. According to our analyses, the great interannual variability appeared to mainly depend on the behavior of reed growth dynamics during the transition to senescence period, what is confirmed through the Enhanced Vegetation Index as a proxy of photosynthetic activity. Additionally, a similar behavior of seasonal and daily patterns of carbon fluxes and ET was found compared with other wetlands under different climates

Stereological comparison of oocyte recruitment and batch fecundity estimates from paraffin and resin sections using spawning albacore (Thunnus alalunga) ovaries as a case study.

Traditional histological protocols in marine fi sh reproductive laboratories using paraf fi n as the embedding medium are now increasingly being replaced with protocols using resin instead. These procedures entail differ- ent degrees of tissue shrinkage complicating direct comparisons of measurement results across laboratories or articles. In this work we selected ovaries of spawning Mediterranean albacore ( Thunnus alalunga ) as the subject of our study to address the issue of structural changes, by contrasting values on oocyte recruitment and fi nal batch fecundity given from the same tissue samples in both paraf fi nandresin.Amodernstereologicalmethod, the oocyte packing density (OPD) theory, was used supported by initial studies on ovarian tissue sampling and measurement design. Examples of differences in the volume fraction of oocyte stages, free space and connective tissue were found between the embedding media. Mean oocyte diameters were smaller in paraf fi nthaninresin with differences ranging between 0.5% in primary growth and 24.3% in hydration (HYD) stage oocytes. Fresh oocyte measurements showed that oocytes shrank as a consequence of the embedding process, reaching the maximaldegreeofshrinkageforoocytesintheHYDstage(45.8%inparaf fi nand26.5%inresin).Inordertoassess the effect of oocyte shrinkage on the OPD result, and thereby on relative batch fecundity (F r ), oocyte diameters corrected and uncorrected for shrinkage, were used for estimations. Statistical signi fi cant differences were found ( P b 0.05) between these two approaches in both embedding media. The average F r was numerically smaller in paraf fi n compared to resin (86 ± 61 vs. 106 ± 54 oocytes per gram of body mass (mean ± SD)). For both embedding media statistical signi fi cant differences ( P b 0.05) were seen between F r results based on either oocytes in the germinal vesicle migration stage or HYD stage. As a valuable adjunct, the present use of the OPD theory made it possible to document that the oocyte recruitment of spawning ovaries of Mediterranean albacore followed the typical pattern of an asynchronous oocyte development and indeterminate fecundityPostprint2,444