PubMed Health⌕ Search

Biomedical subjects

Mustafa Keskin

Publications and source records attributed to Mustafa Keskin.

14 recordsLinked to original sources
PubMed2006

Dynamic phase transition in the kinetic spin- Blume-Capel model under a time-dependent oscillating external field.

We present a study, within a mean-field approach, of the stationary states of the kinetic spin-3/2 Blume-Capel model in the presence of a time-dependent oscillating external magnetic field. We use the Glauber-type stochastic dynamics to describe the time evolution of the system. We have found that the behavior of the system strongly depends on the crystal-field interaction. We can identify two types of solutions: a symmetric one where the magnetization (m) of the system oscillates in time around zero, which corresponds to a paramagnetic phase (P), and an antisymmetric one where m oscillates in time around a finite value different from zero, namely +/-3/2 and +/-1/2 that corresponds to the ferromagnetic-3/2 (F3/2) and the ferromagnetic-1/2 (F1/2) phases, respectively. There are coexistence regions of the phase space where the F3/2, F1/2, (F3/2 + F1/2), F3/2, P(F3/2 + P), F1/2, and P(F1/2 + P), F3/2, F1/2, P(F3/2 + F1/2 + P) phases coexist, hence the system exhibits seven different phases. We obtain the dynamic phase transition points and find six fundamental phase diagrams which exhibit one or three dynamic tricritical points. We have also calculated the Liapunov exponent to verify the stability of the solutions and the dynamic phase transition points.

Journal Article↗
PubMed2006

Pyoderma gangrenosum in a battered child.

Pyoderma gangrenosum is an uncommon cutaneous ulceration, which continues to be a difficult disorder to diagnose and treat. A pediatric case of pyoderma gangrenosum with no associated systemic disorder is presented. The disease was precipitated by physical trauma. The disease was controlled with systemic corticosteroid therapy and then the wound was successfully covered with a split-thickness skin graft from the thigh without any healing problem at the donor site. Although pathergy is well described in the etiopathogenesis of the disease, this is the first case reported that was precipitated after physical assault.

Child↗
PubMed2005

Dynamic phase transition in the kinetic spin-1 Blume-Capel model under a time-dependent oscillating external field.

We study within a mean-field approach the stationary states of the kinetic spin-1 Blume-Capel model in the presence of a time-dependent oscillating external magnetic field. We use the Galuber-type stochastic dynamics to describe the time evolution of the system. We have found that the behavior of the system strongly depends on the crystal field interaction D . We have obtained two types of solutions: a symmetric one, which corresponds paramagnetic phase where the magnetization (m) of the system oscillates in time around zero, and an antisymmetric one where m oscillates in time around a finite value different from zero. There are regions of the phase space where both solutions coexist. The dynamic phase transition from one regime to the other can be a first- or a second-order depending on the region in the phase diagram. Hence, the system exhibits one or more dynamic tricritical point, which depends on the values D . We also calculate the Liapunov exponent to verify the stability of the solutions and the dynamic phase transition points.

Journal Article↗
PubMed2005

Treatment of chronic frontal sinus disease with the galeal-frontalis flap: a long-term follow-up.

BACKGROUND: Management of benign chronic frontal sinus disease is difficult. Patients are frequently seen by multiple specialties for medical treatment and endonasal procedures before they seek or require definitive treatment with frontal sinus obliteration. The progression of the disease may lead to serious or life-threatening conditions such as local bone destruction, periorbital abscess, osteomyelitis, meningitis, cranial epidural abscess, or septicemia. This study presents the use of the galeal-frontalis myofascial flap as part of the treatment of this disease. METHODS: Thirty-one patients with chronic frontal sinus disease requiring obliteration were included in this study; all were approached through a coronal incision. The anterior wall of the frontal sinus was removed and the frontal sinus disease was evacuated. The sinus mucosa was completely removed, and the frontal sinus and nasofrontal duct were totally obliterated with either a unilateral flap or a bilateral galeal-frontalis flap. RESULTS: All patients had failed medical therapy and many had failed endonasal and endoscopic procedures. The mean follow-up was 43.6 months (range, 1 to 125 months). There were two early complications, a seroma and a hematoma. Sinus infection recurred in one patient 3 months postoperatively. The recurrent infection was treated in the same manner, using the available and viable galeal-frontalis flap to obliterate the frontal sinus, with no recurrence after 40 months. CONCLUSIONS: The galeal-frontalis flap has been investigated by angiography and is based on the supratrochlear and supraorbital vessels. Its location and vascularity make it reliable and effective for frontal sinus obliteration. In the head and neck area and elsewhere, filling defects with vascularized tissue prevents infection. A further advantage is that any residual defects are usually well tolerated by patients, and those requesting correction can be easily accommodated. The risks and complications from using exogenous materials and from performing secondary procedures for graft harvest are avoided. Considering that most patients presented with complications from advanced disease and that after one revision no patients have had recurrence of disease, obliterative treatment with the galeal-frontalis myofascial flap should be contemplated earlier in treating patients with chronic frontal sinus disease.

Adolescent↗
PubMed2005

Compartmentalization of massive vascular malformations.

A total of 18 patients with massive vascular malformations of the head and neck region were treated with compartmentalization using nonabsorbable sutures followed by injection of a sclerosant agent into each compartment. The indication for compartmentalization was either to stop potentially uncontrollable, life-threatening hemorrhage during the dissection of the lesion or to reduce its vascularity to allow a less dangerous subsequent resection. Compartmentalization was used in both high-flow and low-flow vascular malformations. In this technique, large nonabsorbable sutures are placed deeply in multiple areas within the lesion. The aim is to divide the malformation into multiple compartments by changing the direction of the suturing; in this way the sclerosing agent is provided with a more effective environment. The sclerosant used was either sodium tetradecyl sulfate 3%, absolute alcohol, or both. The total amount of infiltrate varied from 3 to 35 cc, according to the size of malformation. After compartmentalization, swelling was the most noticeable complication. With this technique, it was possible to treat what were considered untreatable malformations using standard techniques and to control the inevitable serious bleeding.

Adult↗
PubMed2004

Enhancement of nerve regeneration and orientation across a gap with a nerve graft within a vein conduit graft: a functional, stereological, and electrophysiological study.

In this study, the right sciatic nerves of 40 rats were used to determine whether a nerve graft within a vein graft might accelerate and facilitate axonal regeneration, compared with a nerve graft alone. The animals were separated into four groups, as follows: group 1, sham control; group 2 (control), segmental nerve resection and no repair; group 3, segmental nerve resection and nerve grafting; group 4, segmental nerve resection and reconstruction with a nerve graft within a vein conduit graft. For all groups, sciatic functional indices were calculated before the operation and on postoperative days 7 and 90. On postoperative day 90, the sciatic nerves were reexposed and nerve conduction velocities were recorded. The sciatic nerves were harvested from all groups for counting of the myelinated axons with a stereological method. No statistically significant differences with respect to return of gait function, axon count, or nerve conduction were noted between groups 3 and 4 (p > 0.05). However, functional recovery in group 4 on postoperative day 90 was significant, compared with group 2 (p < 0.05); the recovery difference between groups 2 and 3 was not significant (p > 0.05). This study was not able to demonstrate any functional benefits with the use of a nerve graft within a vein graft, compared with standard nerve grafting.

Animals↗
PubMed2003

Reconstruction of columella, membranous septum, and upper lip in a single stage operation.

Reconstruction options for columellar defects together with membranous septum, nasal base, and upper lip are restricted. We present a case successfully treated with bilateral cheek advancement flaps with upper medial, perialar skin flaps to reconstruct the upper lip, columella, nasal base and membranous septum in a single session. This method provides adequate tissue with minimal cosmetic deformity in a single stage for repairing such compound defects.

Aged↗
PubMed2002

Fournier's gangrene as a complication of varicella in a 15-month-old boy.

An inguinal and perianal localization of Fournier's gangrene (FG) in a 15-month-old boy as a complication of the varicella infection is discussed. This is the first presentation of the disease as a complication of the varicella rashes. There were already 57 pediatric FG cases resulting from other causes that had been presented in the medical literature.

Chickenpox↗
PubMedDate not supplied

Unilateral osteotomies for externally deviated noses.

Despite the many methods described for correction of the deviated nose, it still continues to be one of the most challenging problems in rhinoplasty. It is obvious from the literature that the deformities present in the deviated nose can be quite different from patient to patient and that there is no one method that should be used for every deviated nose. Although unilateral osteotomy technique is not a new concept, so far it has not received the interest of plastic surgeons. Shorter operation time, lessened surgical trauma to the nose, lessened intraoperative bleeding, lessened postoperative edema, and lessened recurrence of the deviation are distinct features of the unilateral osteotomy technique that should be considered when planning surgery on such a complex deformity. We present our experiences with unilateral osteotomy and recommend it for patients who have a deviation related to only one side of the nose.

Adolescent↗