Vector bundles on the projective line and finite domination of chain complexes

Finitely dominated chain complexes over a Laurent polynomial ring in one indeterminate are characterised by vanishing of their Novikov homology. We present an algebro-geometric approach to this result, based on extension of chain complexes to sheaves on the projective line. We also discuss the K-theoretical obstruction to extension.Comment: v1: 11 page

Trichinella britovi etiological agent of sylvatic trichinellosis in the Republic of Guinea (West Africa) and a re-evaluation of geographical distribution for encapsulated species in Africa

In West Africa, Trichinella infection was documented in humans and animals from Senegal in the 1960s, and the biological characters of one isolate showed a lower infectivity to domestic pigs and rodents when compared with that of a Trichinella spiralis pig isolate from Europe. To identify the Trichinella species present in West Africa, a survey was conducted in a total of 160 wild animals in the Republic of Guinea. Three Viverridae, one true civet (Viverra civetta) and two African palm civets (Nandinia binotata) from the Fouta Djallon Massif, Pilimini Subprefecture, were found positive by artificial digestion of muscle samples. Trichinella larvae from these three viverrids were identified as Trichinella britovi and no difference was detected in three examined sequences from these African isolates and the reference strain of T. britovi from Europe, indicating common ancestry, an historically continuous geographic distribution, and recent isolation for African and European populations. The detection of T. britovi in West Africa modifies our knowledge about the distribution of encapsulated species of Trichinella in Africa. Thus, Trichinella nelsoni is now considered to have a distribution limited to the Eastern part of the Afrotropical region from Kenya to South Africa. This provides a plausible explanation for the presence of Trichinella T8 in Namibia and South Africa, and further suggests that T. britovi could be the Trichinella species circulating among wild animals of Northern Africa

Nonlinear Optical studies of the Transient Coherence in the Quantum Hall System

We review recent investigations of the femtosecond non-linear optical response of the two-dimensional electron gas (2DEG) in a strong magnetic field. We probe the Quantum Hall (QH) regime for filling factors $\nu \sim 1$. Our focus is on the transient coherence induced via optical excitation and on its time evolution during early femtosecond timescales. We simultaneously study the interband and intraband coherence in this system by using a nonlinear spectroscopic technique, transient three-pulse four wave mixing optical spectroscopy, and a many-body theory. We observe striking differences in the temporal and spectral profile of the nonlinear optical signal between a modulation doped quantum well system (with the 2DEG) and a similar undoped quantum well (without a 2DEG). We attribute these qualitative differences to Coulomb correlations between the photoexcited electron-hole pairs and the 2DEG. We show, in particular, that intraband many-particle coherences assisted by the inter-Landau-level magnetoplasmon excitations of the 2DEG dominate the femtosecond nonlinear optical responce. The most striking effect of these exciton-magnetoplasmon coherences is a large off-resonant four-wave-mixing signal in the case of very low photoexcited carrier densities, not observed in the undoped system, with strong temporal oscillations and unusually symmetric temporal profile.Comment: 22 pages, 9 figures; review article to be published in Solid State Communication

Kosterlitz Thouless Universality in Dimer Models

Using the monomer-dimer representation of strongly coupled U(N) lattice gauge theories with staggered fermions, we study finite temperature chiral phase transitions in (2+1) dimensions. A new cluster algorithm allows us to compute monomer-monomer and dimer-dimer correlations at zero monomer density (chiral limit) accurately on large lattices. This makes it possible to show convincingly, for the first time, that these models undergo a finite temperature phase transition which belongs to the Kosterlitz-Thouless universality class. We find that this universality class is unaffected even in the large N limit. This shows that the mean field analysis often used in this limit breaks down in the critical region.Comment: 4 pages, 4 figure

Band structure and optical anisotropy in V-shaped and T-shaped semiconductor quantum wires

We present a theoretical investigation of the electronic and optical properties of V- and T-shaped quantum wires. Valence-band mixing as well as realistic sample geometries are fully included through an accurate and efficient approach that is described here in detail. We investigate the resulting valence-band structure, which shows some significant peculiarities, such as an anomalously large spin splitting in the lowest heavy-hole subband of T-shaped wires. For both classes of wires we obtain good agreement between calculated optical absorption and recent experimental spectra, and we demonstrate that the analysis of optical anisotropy can be used as an effective tool to extract information on valence states, which is usually very difficult to obtain otherwise

Custom made/patient specific alloplastic total temporomandibular joint replacement in immature patient: a case report and short review of literature

OBJECTIVE: Temporomandibular joint reconstructive surgery in a growing patient represents a challenging situation. Autogenous and alloplastic reconstructive options are being studied in literature; however, there are still some limitations. The objective of this case report is to evaluate a novel custom-made prosthetic system in a 12-year-old TMJ ankylosis patient. CASE PRESENTATION: The patient had complaints of temporomandibular joint ankylosis and hypoplasia. The patient had already been operated two times with autogenous grafts. Swelling and tumefaction were apparent on the right side of the face. Mouth opening was 1.5 centimeters, with limitations in lateral and protrusive movements of the jaws. Hypertonic muscles and pain upon palpation were registered. There were no signs of luxation, fracture, or traumatic avulsion. After examination, unilateral TMJ ankylosis was apparent on TC scans. Revision surgery was planned with the use of true plastic temporomandibular joint customized prosthesis. The patient underwent a TMJ reconstruction surgery using CADCAM custom-made patient specific prosthesis. The follow up period of this patient was 46 months and showed successful healing with no complications. CONCLUSIONS: Replacement of TMJ with custom made alloplastic material that is reported can be considered as a safe and useful option for growing young individuals in selected cases

The Role of Nonequilibrium Dynamical Screening in Carrier Thermalization

We investigate the role played by nonequilibrium dynamical screening in the thermalization of carriers in a simplified two-component two-band model of a semiconductor. The main feature of our approach is the theoretically sound treatment of collisions. We abandon Fermi's Golden rule in favor of a nonequilibrium field theoretic formalism as the former is applicable only in the long-time regime. We also introduce the concept of nonequilibrium dynamical screening. The dephasing of excitonic quantum beats as a result of carrier-carrier scattering is brought out. At low densities it is found that the dephasing times due to carrier-carrier scattering is in picoseconds and not femtoseconds, in agreement with experiments. The polarization dephasing rates are computed as a function of the excited carrier density and it is found that the dephasing rate for carrier-carrier scattering is proportional to the carrier density at ultralow densities. The scaling relation is sublinear at higher densities, which enables a comparison with experiment.Comment: Revised version with additional refs. 12 pages, figs. available upon request; Submitted to Phys. Rev.

Solitary fibrous tumor of parotid gland: a case report and short review of literature

OBJECTIVE: This case report represents a solitary fibrous tumor, which is a very rare neoplasm in the parotid gland. CASE PRESENTATION: 80-year-old Caucasian female patient with palpable, immobile, painless, slow growing, semi-rigid-elastic neoplasm in the left parotid gland, that was existing for four months. There were no signs of inflammation and facial paralysis. The tumor was initially interpreted as a salivary gland neoplasm of uncertain origin. Fine needle aspiration was performed 2 times; however, the precise diagnosis was challenging. The tumor was excised, regional lymphadenectomy was performed. Morphological and immunophenotypical findings were consistent with solitary fibrous tumor of parotid gland. Currently, the patient is under regular follow-up period at 9 months with no evidence of metastasis or recurrence. CONCLUSIONS: Although very rare, solitary fibrous tumor (SFT) should be suspected in cases of slow growing, solid, well-defined nodules of the parotid gland. The SFT of the parotid gland are usually benign tumors, however there is a low risk of recurrency and malignant behavior with metastatic potential. Complete resection of the tumor should be performed since it is crucial for management without any recurrence

Analysis and comparison of quality of life and patients’ satisfaction between dental-skeletal dysmorphisms and Obstructive Sleep Apnea (OSA) patients following orthognathic surgery

OBJECTIVE: The aim of this study was to evaluate the impact of orthognathic surgery on the patients’ satisfaction and quality of life (QoL) in patients with dental skeletal dysmorphisms and Obstructive Sleep Apnea (OSA). SUBJECTS AND METHODS: Patients were grouped into two cohorts, patients with OSA (G1) and patients with dento-skeletal dysmorphisms (G2). SF-36 questionnaire was obtained from all subjects before interventions. A standardized follow-up protocol, including a second SF-36 questionnaire was planned as at least 6 months after surgery. The impact of surgery on satisfaction was evaluated by post-operative patient satisfaction-based survey. RESULTS: 61 patients were included as: 21 OSA (G1), 12 Class II (G2-a) and 28 Class III (G2-b) patients. The mean post-operative follow-up was 65.47±26.36 months. In the SF-36 results, when pre and post operative surveys were compared, the quality of life increased significantly for G1 in all items except for body pain. In G2, when pre and post operative surveys were compared, the quality of life increased significantly in items related to emotional well-being, health transition, role limitations due to emotional problems, while other parameters did not significantly change. When groups were compared, there was no difference among them except for physical functioning which was improved for OSA patients. According to the Rustemeyer results, overall post-operative satisfaction score was 84.92±14.72%. There was a significant difference for patient satisfaction considering facial aesthetics in both groups. For chewing function there was no difference for patient satisfaction in G1, but there was a significant difference in G2 patients. CONCLUSIONS: Orthognathic surgery seems to be beneficial in terms of patients’ satisfaction and patients’ satisfaction for both dental skeletal dysmorphism and OSA patients

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns