3,132 research outputs found
Fluvial Deposition, El Nino and Landscape Construction in Northern Coastal Peru
The El Nino global climate anomaly is a major cause of weather variation that can have far-reaching effects on human populations around the world. Northern coastal Peru is an area of historically major impacts where strong El Nino events have resulted in catastrophic flooding and mass wasting, leading to significant social disruption. There is a growing body of literature on the prehistoric chronology of El Nino and how it affected human populations of the past, but more work is needed. In order to address the timing and characteristics of past El Nino events I investigated the alluvial sedimentary sequences at two archaeological sites of the Moche Period, San Jose de Moro and Huaca del Sol, to infer patterns of past El Nino flooding. Both sites are located adjacent to braided rivers and are constructed on floodplains composed of thick alluvial sequences that are reflective of some aspects of the region’s past climate.
San Jose de Moro is located along the Chaman River, just north of the city of Chepen. Due to the limited size of the river’s drainage basin and the extremely dry nature of the regional environment, flooding is limited to periods of El Nino rainfall and all alluvial deposits at San Jose de Moro are thus thought to be El Nino related. The exposed sedimentary sequence at the site reveals a prominent shift from broad, relatively flat floodplain deposits to cross-bedded, channelized deposits, which may have resulted from several causes, including channel avulsion, a change in stream character related to vegetation stabilization, a change in river base level, stream capture, or a change in climate resulting in an increase in the intensity or frequency of precipitation events. An increase in precipitation may be related to an increase in El Nino activity.
Huaca del Sol is located along the Moche River, near the city of Trujillo. The Moche River has a much larger drainage basin and extends much higher into the Andes Mountains than the Chaman River. Because of this, flooding may be caused by non-El Nino events but El Nino is still one of the major sources of flooding within the drainage. At Huaca del Sol the stratigraphic sequence has significant textural variation throughout, and is consistent with a pattern of regular shifting and avulsion characteristic of braided streams. There is thus no clear evidence of any environmental changes having a significant effect on the stratigraphic sequence at the site.
Both San Jose de Moro and Huaca del Sol are located on floodplain surfaces created at least in part by El Nino-driven aggradation that produced broad, elevated areas with decreased risk of El Nino flooding. The presence of these sites on this landscape shows that this environment was attractive for both occupation and ceremonialism. These results demonstration that in addition to being a cause of weather variation and catastrophism, El Nino should also be seen as a constructor of favorable landscapes that is essential to understanding the physical setting of prehistoric human settlements in northern coastal Peru
On the Digital Holographic Interferometry of Fibrous Material, I. Optical Properties of Polymer and Optical Fibers
The digital holographic interferometry (DHI) was utilized for investigating
the optical properties of polymer and optical fibers. The samples investigated
here were polyvinylidene fluoride (PVDF) polymer fiber and graded-index (GRIN)
optical fiber. The phase shifting Mach-Zehnder interferometer was used to
obtain five phase-shifted holograms, in which the phase difference between two
successive holograms is pi/2, for each fiber sample. These holograms were
recorded using a CCD camera and were combined to gain a complex wavefield,
which was numerically reconstructed using the convolution approach into
amplitude and phase distributions. The reconstructed phase distribution was
used to determine the refractive index, birefringence and refractive index
profile of the studied samples. The mean refractive index has been measured
with accuracy up to 4 {\times} 10-4. The main advantage of DHI is to overcome
the manual focusing limitations by means of the numerical focusing. The results
showed accurate measurements of the optical properties of fibers.Comment: abstract, reference
Patterns in the multiannual course of growing season in Central Europe since the end of the 19th century
The research identified patterns in the multiannual course of start and end dates, and length of growing sea son (GS) in Central Europe since the end of the 19th century in selected cities of Central Europe in the period 1893-2020. GS start in the analysed stations was characterised by high year-to-year variability, particularly in those located more southwards, i.e. in Prague and Vienna. A smaller variability occurred in GS end dates. The GS was subject to prolon gation, although these changes in particular cities were uneven and had different causes. In Toruń and Potsdam, its increase was caused by a greater shift of the end date, and in the remaining stations, it was determined by its earlier start date. Two subperiods were distinguished that differ in terms of intensity of changes of the start and end dates, as well as the length of the GS. The intensification was observed recently
Legitimising accession: Transformation politics and elite consensus on EU membership in Poland, 1989-2003.
This thesis considers the evolution of Poland's party-political consensus on accession to the European Union, starting with the elections to the contract parliament in June 1989 and ending with the accession referendum in June 2003. The main finding is that the establishment of consensus in favour of accession among Poland's political elites proved much more challenging than the elites' declarations of support suggest. Although most parties declared support for accession, throughout the entire pre-accession period they also supported policy proposals that contradicted accession conditions. The EU's strict neoliberal economic requirements and the loss of national sovereignty accession entailed proved particularly challenging. Rather than reconcile their policy proposals with EU's conditions, or change their stance on accession, parties rhetorically re-presented the EU into different visions that aligned with their ideological offering. Declarations of support for 'Social Europe', 'Christian Europe' or the 'Europe of Nations' gave the appearance of consensus. But in fact no in-depth consensus was possible since the way in which political groupings presented the 'Europe' they claimed to support was so different as to remove a common denominator they could agree on. As a result, the single biggest change Polish society experienced since 1989 was never really addressed in political debate. The integration project was propelled forward not by in-depth political consensus but by a series of rhetorical compromises. At each stage of the accession process the parties' inability to negotiate more than a nominal consensus prevented meaningful public debate. During each electoral contest of the pre-accession period voters were presented with ambiguous rhetoric in place of alternative policy options that would have enabled the electorate to hold decision makers to account
Physicochemical Characterization and Dissolution Studies of Solid Dispersions of Clotrimazole with Pluronic F127
Purpose: To evaluate the physicochemical properties of clotrimazole (CLT) solid dispersion with Pluronic F127 (PLU).Methods: Solid dispersions of the antifungal drug, clotrimazole, were prepared with Pluronic F127 using grinding (PM) and fusion (FUS) methods. Physicochemical characterization of the dispersions were performed using differential scanning calorimetry (DSC), x-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR). In vitro drug release was carried out using the rotating disc method.Results: These studies showed that there was no chemical interaction between CLT and PLU. Release studies on the SDs showed a significant (> 90-fold) improvement in dissolution rate compared to pure CLT. The greatest increase in dissolution (< 80 %) was observed for the solid dispersion (CLT/PLU) prepared by FUS in the ratio 60:40 % w/w.Conclusion: The results demonstrate that the developed solid dispersion system is a suitable approach for enhancing the dissolution rate of CLT.Keywords: Clotrimazole, Pluronic F127, Solid dispersion, Dissolution, Differential scanning calorimetry, Phase diagra
Coulomb Corrections for Interferometry Analysis of Expanding Hadron Systems
The problem of the Coulomb corrections to the two-boson correlation functions for the systems formed in ultra-relativistic heavy ion collisions is considered for large effective system volumes. The modification of the standard zero-distance correction (so called Gamow or Coulomb factor) has been proposed for such a kind of systems. For the 1r+1r+ and [(+[(+ correlation functions the analytical calculations of the Coulomb correction are compared with the exact numerical results
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