846 research outputs found
Partition Functions of Pure Spinors
We compute partition functions describing multiplicities and charges of
massless and first massive string states of pure-spinor superstrings in
3,4,6,10 dimensions. At the massless level we find a spin-one gauge multiplet
of minimal supersymmetry in d dimensions. At the first massive string level we
find a massive spin-two multiplet. The result is confirmed by a direct analysis
of the BRST cohomology at ghost number one. The central charges of the pure
spinor systems are derived in a manifestly SO(d) covariant way confirming that
the resulting string theories are critical. A critical string model with
N=(2,0) supersymmetry in d=2 is also described.Comment: LaTex, 30 p
Is there a direct role for erythrocytes in the immune response?
Erythrocytes are highly abundant circulating cells in the vertebrates, which, with the notable exception of mammals, remain nucleated throughout the entire life cycle. The major function associated with these cells is respiratory gas exchange however other functions including interaction with the immune system have been attributed to these cells. Many viral, prokaryotic and eukaryotic pathogens directly target this cell type and across the vertebrate group a significant number of related pathologies have been reported. Across the primary literature mechanisms of interaction, invasion and replication between viruses and erythrocytes have been well described however the functional response of the erythrocyte has been poorly studied. A fragmented series of reports spanning the vertebrates suggests that these cells are capable of functional responses to viral infection. In contrast, in-depth proteomic studies using human erythrocytes have strongly progressed throughout the past decade providing a rich source of information related to protein expression and potential function. Furthermore information at the gene expression level is becoming available. Here we provide a review of erythrocyte-pathogen interactions, erythrocyte functions in immunity and propose in light of recent -omics research that the nucleated erythrocytes may have a direct role in the immune response
El Niño–Southern Oscillation (ENSO)-driven hypersedimentation in the Poechos Reservoir, northern Peru
Although extreme El Niño events (EENEs) have always impacted
hydrological anomalies and sediment transport in South America, their
intensification by global warming and their association with changes in
human activities and land cover after humid periods may lead to the
acceleration of sediment transfers in river systems and dam reservoirs. This
situation may threaten soil and water resources in arid and semiarid regions
highly dependent on water originating from large dams. In this study, we
investigated the sediment sequence accumulated in the Poechos Reservoir
(northern Peru) and provided a retrospective reconstruction of the
interactions of El Niño–Southern Oscillation (ENSO), agricultural
practices and vegetation cover changes with sediment dynamics (1978–2019). To
this end, a sediment core was dated and characterized by physical and
chemical analyses (e.g., scanner tomography, X-ray fluorescence, particle
size analysis) to estimate the evolution of sedimentation rates and
changes in sediment sources during the last 5 decades.
Sediment tracing results indicated the occurrence of changes in sediment
sources associated with positive and negative phases of the Eastern Pacific
index with a greater contribution of the lowland dry-forest area in
comparison to that of the Andean area to sediment during the El Niño
events (mean contribution of 76 %; up to 90 % during the coastal El
Niño events (CENEs) of 2016–2017). This source contribution was mostly
controlled by the stationary rainfall occurring during the EENEs in the lowland dry-forest area characterized by a low vegetation cover. Overall, after an extreme phase of ENSO, like after the
EENE 1982–1983, the normal discharges and persistent sediment supplies from
the middle- and upper-catchment parts led to river aggradation and the
storage of substantial amounts of sediment in alluvial plains. In the
absence of a significant EENE between 1983 and 1997, the large volume of
sediment stored in the alluvial plains was exported by the EENE 1997–1998
resulting in an increase in sedimentation rate of 140 % after 1997 with
a significant aggradation of the deltaic zone of the reservoir. In addition
to the impact of extreme climate events on sediment dynamics, the
development of agriculture along the riverine system after an extreme phase
of ENSO increased the availability of sediments in the main channel of the
rivers, easily transported by the next EENE. This study suggests that
intensification of human activities associated with a higher frequency of
extreme rainfall events amplified the quantity of sediment transported by
the river system, which will significantly decrease the lifespan of the
reservoir, which is essential to meeting the freshwater demands of the farmers and the
populations living in this arid and semiarid region.</p
The use of straw mulch as a strategy to prevent extreme soil erosion rates in citrus orchard. A Rainfall simulation approach
Not only the Sahel (Haregeweyn et al., 2013), the deforested land (Borelli et al., 2013) the chinese Plateau are
affected by intense soil erosion rates (Zhao et al., 2013). Soil erosion affect agriculture land (Cerdà et al., 2009),
and citrus orchards are being seeing as one of the crops with the highest erosion rates due to the managements
that avoid the catch crops, weeds or litter. Example of the research carried out on citrus orchards is found in the
Mediterranean (Cerdà and Jurgensen, 2008; 2009; Cerdà et al., 2009a; 2009b; Cerdà et al., 2011; 2012) and in
China (Wu et al., 1997; Xu et al., 2010; Wang et al., 2011; Wu et al., 2011; Liu et al., 2011; Lü et al., 2011; Xu et
al., 2012), and they confirm the non sustainable soil losses measured. The land management in citrus plantations
results in soil degradation too (Lu et al., 1997; Lü et al., 2012; Xu et al., 2012). The use of cover crops to reduce
the soil losses (Lavigne et al., 2012; Le Bellec et al., 2012) and the use of residues such as dried citrus peel has
been found successful. There is a need to find new plants or residues to protect the soils on citrus orchards.
Agriculture produces a high amount of residues. The pruning can contribute with a valuable source of nutrients
and a good soil protection. The leaves of the trees, and some parts of the plants, once harvest can contribute to
reduce the soil losses. Due to the mechanization of the agriculture, and the reduction of the draft animals (mainly
horses, mules, donkeys and oxen) the straw is being a residue instead of a resource. The Valencia region is the
largest producer of citrus in Europe, and the largest exporter in the world. This citrus production region is located
in the eastern cost of Spain where we can find the rice production area of the l’Albufera Lagoon paddy fields,
the third largest production region in Spain. This means, a rice production region surrounded by the huge citrus
production region. There, the rice straw is not used in the paddy fields after harvesting and the straw is being as
a residue that damages the air quality when burnt, the water quality due to the decomposition and the methane
production, and is not accepted in the field by the farmers. This is a new problem as few years ago the rice straw
was use for animal feeding. Many attempts were developed in the last decade to remove and use the straw to avoid
fires and water pollution (Iranzo et al., 2004; Silvestre et al., 2013).
Our goal is to test if a residue such as the rice straw can be transformed as a resource: soil erosion control. Straw
has been seen as a very efficient to reduce the water losses in agriculture land (García Moreno et al., 2013), the
soil losses in fire affected land (Robichaud et al., 2013a; 2013b; Fernandez and Vega, 2014), and soil properties
(García Orenes et al., 2009; 2010; Jordán et al., 2010; García Orenes 2012).
Rainfall simulations under 55 mm h-1 rainfall intensity during one hour on 0,25 m2 plots were carried out on plots
paired plots: bare and covered with straw. The plots covered with straw had different straw mulch cover: from 10
to 100 % cover and from 0,005 g m2 to 300 g m2. The results show a positive effect of the straw cover that show
an exponential relation between the straw cover and weight with the sediment yield.
Acknowledgements
The research projects GL2008-02879/BTE, LEDDRA 243857 and RECARE supported this research
Are Sensory-Motor Relationships Encoded ad hoc or by Default?: An ERP Study
Published: 03 May 2019In this event-related potentials study we tested whether sensory-motor relations
between concrete words are encoded by default or only under explicit ad hoc
instructions. In Exp. 1, participants were explicitly asked to encode sensory-motor
relations (e.g., “do the following objects fit in a pencil-cup?”), while other possible
semantic relations remained implicit. In Exp. 2, using the same materials other group of
participants were explicitly asked to encode semantic relations (e.g., “are the following
objects related to a pencil-cup?”), and the possible sensory-motor relations remained
implicit. The N400 component was sensitive to semantic relations (e.g., “desk” related to
“pencil-cup”) both under implicit (Exp. 1) and explicit instructions (Exp. 2). By contrast,
most sensory-motor relations (e.g., “pea” fitting in “pencil-cup”) were encoded ad hoc
under explicit instructions (Exp. 1). Interestingly some sensory-motor relations were also
encoded implicitly, but only when they corresponded to “functional” actions associated
with high-related objects (e.g., “eraser” fitting in “pencil-cup”) and occurring at a late
time window (500–650 ms; Exp. 2), suggesting that this type of sensory-motor relations
were encoding by default.This research was supported by the Spanish MINECO (Grant Nos. PSI2015-66277-R to MdV and PSI2016-79624-P to HB) and the European Regional Development Funds
All night analysis of time interval between snores in subjects with sleep apnea hypopnea syndrome
Sleep apnea–hypopnea syndrome (SAHS) is a serious sleep disorder, and snoring is one of its earliest and most consistent symptoms. We propose a new methodology for identifying two distinct types of snores: the so-called non-regular and regular snores. Respiratory sound signals from 34 subjects with different ranges of Apnea-Hypopnea Index (AHI = 3.7–109.9 h−1) were acquired. A total number of 74,439 snores were examined. The time interval between regular snores in short segments of the all night recordings was analyzed. Severe SAHS subjects show a shorter time interval between regular snores (p = 0.0036, AHI cp: 30 h−1) and less dispersion on the time interval features during all sleep. Conversely, lower intra-segment variability (p = 0.006, AHI cp: 30 h−1) is seen for less severe SAHS subjects. Features derived from the analysis of time interval between regular snores achieved classification accuracies of 88.2 % (with 90 % sensitivity, 75 % specificity) and 94.1 % (with 94.4 % sensitivity, 93.8 % specificity) for AHI cut-points of severity of 5 and 30 h−1, respectively. The features proved to be reliable predictors of the subjects’ SAHS severity. Our proposed method, the analysis of time interval between snores, provides promising results and puts forward a valuable aid for the early screening of subjects suspected of having SAHS
Heat shock induced changes of adipokines gene expression in 3T3-L1 adipocytes
To study the effects of heat shock on adipokines gene expression 3T3-L1 adipocytes were used. Heat shock differently affected gene expression of leptin, adiponectin and acylation stimulating protein (ASP): exposure of cells to temperature higher than 39°C caused upregulation of leptin and downregulation of adiponectin and ASP genes. The present study provides the first evidence about the effects of heat shock on adipokines gene expression. Changes in gene expression of the three adipokines may help to explain the alteration of lipid metabolism and liver functionality occurring in animals exposed to hot conditions
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