The new insight into dynamic crossover in glass forming liquids from the apparent enthalpy analysis

One of the most intriguing phenomena in glass forming systems is the dynamic crossover (T(B)), occurring well above the glass temperature (T(g)). So far, it was estimated mainly from the linearized derivative analysis of the primary relaxation time τ(T) or viscosity η(T) experimental data, originally proposed by Stickel et al. [J. Chem. Phys. 104, 2043 (1996); J. Chem. Phys. 107, 1086 (1997)]. However, this formal procedure is based on the general validity of the Vogel-Fulcher-Tammann equation, which has been strongly questioned recently [T. Hecksher et al. Nature Phys. 4, 737 (2008); P. Lunkenheimer et al. Phys. Rev. E 81, 051504 (2010); J. C. Martinez-Garcia et al. J. Chem. Phys. 134, 024512 (2011)]. We present a qualitatively new way to identify the dynamic crossover based on the apparent enthalpy space (H(a)(') = dlnτ/d(1/T)) analysis via a new plot lnH(a)(') vs. 1∕T supported by the Savitzky-Golay filtering procedure for getting an insight into the noise-distorted high order derivatives. It is shown that depending on the ratio between the "virtual" fragility in the high temperature dynamic domain (m(high)) and the "real" fragility at T(g) (the low temperature dynamic domain, m = m(low)) glass formers can be splitted into two groups related to f < 1 and f > 1, (f = m(high)∕m(low)). The link of this phenomenon to the ratio between the apparent enthalpy and activation energy as well as the behavior of the configurational entropy is indicated.

Complex genital system of a haplogyne spider (Arachnida, Araneae, Tetrablemmidae) indicates internal fertilization and full female control over transferred sperm

The female genital organs of the tetrablemmid Indicoblemma lannaianum are astonishingly complex. The copulatory orifice lies anterior to the opening of the uterus externus and leads into a narrow insertion duct that ends in a genital cavity. The genital cavity continues laterally in paired tube-like copulatory ducts, which lead into paired, large, sac-like receptacula. Each receptaculum has a sclerotized pore plate with associated gland cells. Paired small fertilization ducts originate in the receptacula and take their curved course inside the copulatory ducts. The fertilization ducts end in slit-like openings in the sclerotized posterior walls of the copulatory ducts. Huge masses of secretions forming large balls are detectable in the female receptacula. An important function of these secretory balls seems to be the encapsulation of spermatozoa in discrete packages in order to avoid the mixing of sperm from different males. In this way, sperm competition may be completely prevented or at least severely limited. Females seem to have full control over transferred sperm and be able to express preference for spermatozoa of certain males. The lumen of the sperm containing secretory balls is connected with the fertilization duct. Activated spermatozoa are only found in the uterus internus of females, which is an indication of internal fertilization. The sperm cells in the uterus internus are characterized by an extensive cytoplasm and an elongated, cone-shaped nucleus. The male genital system of I. lannaianum consists of thick testes and thin convoluted vasa deferentia that open into the wide ductus ejaculatorius. The voluminous globular palpal bulb is filled with seminal fluid consisting of a globular secretion in which only a few spermatozoa are embedded. The spermatozoa are encapsulated by a sheath produced in the genital system. The secretions in females may at least partly consist of male secretions that could be involved in the building of the secretory balls or play a role in sperm activation. The male secretions could also afford nutriments to the spermatozoa.

Rosette-forming glioneuronal tumor of the fourth ventricle: Report of two cases with a differential diagnostic overview

We report on clinicopathological findings in two cases of rosette-forming glioneuronal tumor of the fourth ventricle (RGNT) occurring in females aged 16 years (Case 1) and 30 years (Case 2). Symptoms included vertigo, nausea, cerebellar ataxia, as well as headaches, and had been present for 4-months and 1 week, respectively. Magnetic resonance imaging (MRI) indicated a cerebellar-based tumor of 1.8cm (Case 1) and 5cm (Case 2) diameter each, bulging into the fourth ventricle. Case 2 involved a cyst-mural-nodule configuration. In both instances, the solid component appeared isointense on T(1) sequences, hyperintense in the T(2) mode, and enhanced moderately. Gross total resection was achieved via suboccipital craniotomy. However, functional recovery was disappointing in Case 1. On microscopy, both tumors comprised an admixture of low-grade astrocytoma interspersed with circular aggregates of synaptophysin-expressing round cells harboring oligodendrocyte-like nuclei. The astrocytic moiety in Case 1 was nondescript, and overtly pilocytic in Case 2. The architecture of neuronal elements variously consisted of neurocytic rosettes, of pseudorosettes centered on a capillary core, as well as of concentric ribbons along irregular lumina. Gangliocytic maturation, especially "floating neurons", or a corresponding immunoreactivity for neurofilament protein was absent. Neither of these populations exhibited atypia, mitotic activity, or a significant labeling for MIB-1. Cerebellar parenchyma included in the surgical specimen did not reveal any preexisting malformative anomaly. Despite sharing some overlapping histologic traits with dysembryoplastic neuroepithelial tumor (DNT), the presentation of RGNT with respect to both patient age and location is consistent enough for this lesion to be singled out as an autonomous entity.