The miniaturization of memory devices like hard disks, random access memories and their read heads has made the detailed study of magnetic materials at nano scale imperative. The characteristics of magnetic material are highly sensitive to different growth conditions, temperature and nature of neigbouring material, as a result the magnetic characteristics may be tailored. In this research work single Ni thin films sandwiched between Cu buffer layer and Cu capping layer are grown on Si(001) substrates by resistive heating in an ultra high vacuum chamber at different substrate temperature .The temperatures of substrate chosen for this study are 300K (room temperature) and very low temperature, approximately 30K. These thin films are grown with different Ni thickness ranging from 1nm to 10nm. A comparison of physical and magnetic properties of Ni thin films is done with respect to Ni thickness as well as with respect to the substrate temperature. Multilayers of Ni thin films are also grown. These multilayers are grown on Si(111) with a Cu buffer layer, a Cu spacer layer between the Ni layers and a Cu capping layer. The multilayers are grown with different Ni thicknesses, ranging from 1nm to 3nm, and with different Cu spacer layer thickness, ranging from 10nm to 20nm. A comparison of physical and magnetic characterization is done with respect to Ni thickness and with respect to different Cu spacer thickness. It is found that the thickness of the Ni thin film as well as the temperature of the substrate affects the physical and magnetic properties of the Cu/Ni/Cu/Si(001) samples. The variation in grain size of samples with different Ni thickness and different substrate temperature, shows different trend. Grain size of samples grown at low substrate temperature is larger. The values of saturation magnetization of different Ni thickness samples, grown at room temperature of substrate, increases with increase in Ni thickness. In Cu/Ni/Cu/Ni/Cu/Si(111) multilayers with different Ni thicknesses indicate that the grain size is affected by the thickness of the Ni film. The value of saturation magnetization is almost the same for different Ni thicknesses. Grain size is affected in multilayers with different Cu spacer layers as well. The saturation magnetization is nearly constant for different spacer layers with same Ni thickness. A shift in the hysteresis loop is also observed in the positive direction for most of the multilayers.
امام خمینی حق مغفرت کرے عجب آزاد مرد تھا انقلاب ایران کے تاریخ ساز قائد، ایران میں اسلامی جمہوریہ کے بانی، روحانی پیشوا اور عالمِ اسلام کے ایک عظیم فرزند علامہ روح اﷲ آیت اﷲ خمینی مرحوم ۳؍جون بروز شنبہ کواپنی علالت اورآپریشن میں ناکامی کے بعد بالآخر وہاں پہنچ گئے جہاں ہم میں سے ہرایک کوایک دن جانا ہے۔ اِنَّالِلّٰہِ وَاِنَّا اِلَیْہِ راجِعُوْن۔علامہ خمینی کے انتقال کی خبر سے مسلم ممالک میں صفِ ماتم بچھ گئی، موت اَٹل اوربَرحق ہے اور یہ تلخ گھونٹ ہر متنفّس کواپنے وقت پر پینا ہے۔’’کل نفسٍ ذائقۃُ الموت‘‘ اور ’’اِذَا جَآء اجُلُھَا لَا ےَسْتَاخِرُون ساعۃ وَلَا یستقدمون ‘‘ فرمان الٰہی ہے۔ تاہم اس کار گاہِ ہستی میں بعض شخصیات ایسی بھی پیدا ہوتی ہیں، جن کے دنیا سے اُٹھ جانے کے بعد جوخلاء پیداہوتا ہے،اس کاپُر ہونا ممکن نہیں ہوتا ہے۔ یہ حقیقت ہے کہ موجودہ صدی میں جن اہم شخصیات نے جدید تاریخ پرگہرے نقوش واثرات چھوڑے ہیں، اور ایک لمبی مدت تک جن کی یاد باقی رکھی جائے گی ان میں مرحوم رہنما کی انقلاب آفریں ذات بھی شامل ہے۔ بلاشبہ علامہ خمینی کے انتقال سے سیاسی بالغ نظری، جرأت،بے باکی انقلاب، عزم اور خودداری کے ایک دور کاخاتمہ ہوگیا، علامہ خمینی اپنی ذاتی خصوصیات اوصاف اور کمالات کے اعتبار سے ایک پُرکشش، باوضع اوربھاری بھرکم شخصیت کے مالک تھے ان کے بعض عقائد وافکار ونظریات ،سیاسی سوچ و اپروچ اور طریقِ کارسے جمہوری اختلاف کے باوجود ان کی اصول پسندی، جذبۂ حرّیت ،ایثار وقربانی اور جدوجہد کی تعریف کیے بغیر چارۂ کار نہیں ہے۔ علامہ آیت اﷲ خمینی ۱۹۰۰ء میں شمالی ایران کے جران نامی ایک قصبہ خمین میں پیدا ہوئے، کل عمر ۸۹؍ سال کی پائی، بچپن سے ہی آپ کی تعلیم وتربیت ایک خاص ماحول میں ہوئی۔آپ نے اسلامیات ،دینیات ،فقہ اور فلسفہ کے شعبوں...
Location of Pakistan has great geo-political and geo-strategic significance in the South Asian region. Pakistan played an important role for the strategic goals of the United States during the ruling periods of President Zia-ul-Haq and President Musharraf. As a frontline state Pakistan received economic and military assistance, during the period of President Zia-ul-Haq, for supporting US interests against Soviet invasion in Afghanistan. After 9/11, due to its strategic location, Pakistan became the ally of the United States against terrorism and the biggest beneficiary of US economic assistance in the region. However, as a result of these policies Islamic extremism, sectarian violence and ethnic cleavages cropped up in the society, shattering social and cultural values. The purpose of this research paper is to highlight the key role played by Pakistan as a frontline state and its impact on the Pakistani society. This research paper follows descriptive and analytical methods.
Compression of data has become a worldwide phenomenon during the past few decades for rea- son of achieving savings in band-width (BW) and hence makes it cost effective. The widespread practice of encryption of data has generated interest for many decades and it mainly aims at pro- tection of data. Combining these two apparently contrary processes (in terms of BW) is quite challenging. Whereas the research on concurrent data compression and data protection (encryp- tion) is still on, the methodology adopted by the author is unique and quite new. The most impor- tant aim of data compression technique is the need for curtailing the data storage and communi- cation expenses. The source message (long) is converted to a codeword (small). The key objec- tive of data encryption is to guard the integrity of data if it is intercepted by an eavesdropper. The plaintext is transformed in to ciphertext using an encryption key or keys. Combining the processes of compression and encryption together must be done in this order, that is, compres- sion followed by encryption because all compression techniques heavily rely on the redundancies inherently part of a regular text or speech. The speech compression has been achieved using Lempel-Ziv 78 algorithm and a new algorithm for encryption/decryption, named ―The Random- One, abbreviated as TR-1‖ is developed during this study and is thoroughly tested. The results obtained are quite encouraging. Firstly, contrary to the use of conventional methods the algo- rithm developed in this study does not use exclusive-OR (XOR) operation in Permutation (P) and Distribution (D) boxes for producing ciphertext from the plaintext. In this scheme pseudo ran- dom number (PRN) is used only to deceive the intruder by adding more confusion (meaning compared to the confusion due to the use of some tested algorithms used in this research). In fact only the sender of information and the intended recipient (not intruders) should be aware of the 44 bit positions filled by the PRN in a 128 word. The intended recipient discards these during deciphering process at the right time (these are disposed of before performing the inverse map- ping in the P-Box). Secondly, protection against attacks is further ensured by using two supple- mentary keys, one for the P-Box, and another for the D-box. In addition the routine key-set of the N selected algorithms further enhances the security. In a small set-up, the distribution of key-set can be mutually agreed upon by the users; but in a large set-up, the distribution of these sets can be accomplished using standard key distribution techniques. Moreover, the proposed algorithm- - also differs from the other methods currently in use due to deployment of a ―sentinel marker”; which is not adopted by other algorithms and this proposal is purely the brain child of the author. The sentinel marker is part of the secret key which is pre-decided and predetermined by the sender and the intended recipient of the information. Twenty bits (out of a total of 128) are used for the sentinel marker which amounts to 2^20 = 1,048,576 possibilities combined with 2^44 = 17.6 trillion possibilities of the ciphertext produced by the PRN. The job for the cryptanalyst to break this cipher becomes formidable and a fool-proof security of data is ensured.